Digital Camera Patent AbstractA digital camera includes a first image sensor, a first wide angle
lens for forming a first image of a scene on the first image sensor;
a second image sensor, a zoom lens for forming a second image of
the same scene on the second image sensor, a control element for
selecting either a first sensor output from the first image sensor
or a second sensor output from the second image sensor, and a processing
section for producing the output image from the selected sensor
output. In one variation of this embodiment, the first lens is also
a zoom lens, where the maximum focal length of the first lens is
less than or equal to the minimum focal length of the second zoom
lens.
Digital Camera Patent ClaimsThe invention claimed is:
1. An electronic camera for producing an output image of a scene,
said electronic camera comprising: a first image sensor for generating
a first sensor output; a first lens for forming a first image of
the scene on the first image sensor, wherein the first lens has
a fixed focal length; a second image sensor for generating a second
sensor output; a zoom lens pointing in the same direction as the
first lens and forming a second image of the same scene on the second
image sensor, wherein the zoom lens is adjustable between a minimum
focal length and a maximum focal length to provide the second image,
wherein the first and second images formed on the first and second
image sensors have different aspect ratios, including a panoramic
aspect ratio for the first image sensor, and wherein the panoramic
aspect ratio of the first image sensor is adjustable; a control
element for selecting either the first sensor output from the first
image sensor or the second sensor output from the second image sensor,
thereby providing a selected sensor output; a first user control
for enabling a panoramic mode and a second user control for setting
a zoom position for the camera; and a processing section for producing
the output image from the selected sensor output.
2. The electronic camera as claimed in claim 1 wherein the second
user control allows a user to select a focal length and wherein
the control element is responsive to the second user control for
selecting a corresponding sensor output.
3. The electronic camera as claimed in claim 2 wherein the fixed
focal length of the first lens is less than the minimum focal length
of the zoom lens, thereby leaving a focal length gap therebetween.
4. The electronic camera as claimed in claim 3 wherein the processing
section includes an electronic zooming capability for electronically
zooming over at least a portion of the focal length gap.
5. The electronic camera as claimed in claim 4 wherein the second
user control allows for selecting a zoom position, whereby the zoom
position is characterized as (a) an optical focal length when it
is the fixed focal length of the first lens or within the focal
lengths of the zoom lens and (b) an electronic zoom amount when
within the gap between the fixed focal length of the first lens
and the minimum focal length of the zoom lens.
6. The electronic camera as claimed in claim 1 wherein, when the
panoramic mode is enabled, the setting of the second user control
engages the processing stage to modify the aspect ratio of the first
image captured by the first sensor.
7. The electronic camera as claimed in claim 1 wherein the first
and second image sensors are differently sized and an optical path
distance between each lens and its image sensor is substantially
the same, thereby providing a pair of lens systems which have different
effective focal lengths for the same optical path distances.
8. The electronic camera as claimed in claim 1 further comprising:
a plurality of additional image sensors for generating a corresponding
plurality of additional sensor outputs; and a plurality of additional
lenses for forming a corresponding plurality of additional images
of the scene on the plurality of additional image sensors; wherein
the control element selects either the first sensor output from
the first image sensor, the second sensor output from the second
image sensor or any one of the plurality of additional sensor outputs
from the plurality of additional image sensors, thereby providing
a selected image output.
9. The electronic camera as claimed in claim 8 wherein at least
one of the additional lenses is a zoom lens.
10. The electronic camera as claimed in claim 1 wherein the fixed
focal length of the first lens has a 35 mm equivalent focal length
of less than 25 mm.
11. The electronic camera as claimed in claim 10 wherein the minimum
focal length of the zoom lens has a 35 mm equivalent focal length
of greater than 30 mm.
12. An electronic camera for producing a output image of a scene,
said electronic camera comprising: a first image sensor for generating
a first sensor output; a first lens having a fixed focal length
for forming a first image of the scene on the first image sensor;
a second image sensor for generating a second sensor output; a wide
zoom lens pointing in the same direction as the first lens and forming
a second image of the same scene on the second image sensor, wherein
the wide zoom lens is adjustable through a first set of focal lengths
between a minimum focal length and a maximum focal length to provide
the second image; a third image sensor for generating a third sensor
output; a tele zoom lens pointing in the same direction as the first
lens and forming a third image of the same scene on the third image
sensor, wherein the tele zoom lens is adjustable through a second
set of focal lengths between a minimum focal length and a maximum
focal length to provide the third image; a control element for selecting
either the first sensor output from the first image sensor, the
second sensor output from the second image sensor or the third sensor
output from the third image sensor, thereby providing a selected
sensor output; and a processing section for producing the output
image from the selected sensor output.
13. The electronic camera as claimed in claim 12 further comprising
a user control that allows a user to select an appropriate focal
length and wherein the control element is responsive to the user
control for selecting a corresponding image output.
14. The electronic camera as claimed in claim 13 wherein the fixed
focal length of the first lens is less than the minimum focal length
of the wide zoom lens, thereby leaving a focal length gap therebetween,
and wherein the processing section includes an electronic zooming
capability for electronically zooming over at least a portion of
the focal length gap.
15. An electronic camera that provides a zoom setting over a range
including a wide angle optical focal length and a group of optical
focal lengths provided by at least one tele zoom lens, wherein at
least some of the intervening focal lengths in the gap between the
wide angle focal length and the zoom focal lengths of the tele zoom
are provided by electronically zooming up from an image captured
at the wide angle optical focal length, wherein the wide angle optical
focal length is provided by an additional zoom lens and the intervening
focal lengths in the gap between the wide angle focal length and
the zoom focal lengths are provided by electronically zooming up
from an image captured at a maximum focal length of the additional
zoom lens.
16. An electronic camera for producing an output image of a scene,
said electronic camera comprising: a first image sensor for generating
a first sensor output; a first lens for forming a first image of
the scene on the first image sensor; a second image sensor for generating
a second sensor output; a zoom lens pointing in the same direction
as the first lens and forming a second image of the same scene on
the second image sensor, wherein the zoom lens is adjustable between
a minimum focal length and a maximum focal length to provide the
second image, and wherein the first and second image sensors are
differently sized and an optical path distance between each lens
and its image sensor is substantially the same, thereby providing
a pair of lens systems which have different effective focal lengths
for the same optical path distances; a control element for selecting
either the first sensor output from the first image sensor or the
second sensor output from the second image sensor, thereby providing
a selected sensor output; and a processing section for producing
the output image from the selected sensor output.
17. The electronic camera as claimed in claim 16 wherein the first
lens has a fixed focal length.
18. The electronic camera as claimed in claim 17 wherein the fixed
focal length of the first lens has a 35 mm equivalent focal length
of less than 25 mm.
19. The electronic camera as claimed in claim 18 wherein the minimum
focal length of the zoom lens has a 35 mm equivalent focal length
of greater than 30 mm.
20. The electronic camera as claimed in claim 17 further comprising
a user control that allows a user to select a focal length and wherein
the control element is responsive to the user control for selecting
a corresponding sensor output.
21. The electronic camera as claimed in claim 20 wherein the fixed
focal length of the first lens is less than the minimum focal length
of the zoom lens, thereby leaving a focal length gap therebetween.
22. The electronic camera as claimed in claim 21 wherein the processing
section includes an electronic zooming capability for electronically
zooming over at least a portion of the focal length gap.
23. The electronic camera as claimed in claim 22 wherein the user
control allows for selecting a zoom position, whereby the zoom position
is characterized as (a) an optical focal length when it is the fixed
focal length of the first lens or within the focal lengths of the
zoom lens and (b) an electronic zoom amount when within the gap
between the fixed focal length of the first lens and the minimum
focal length of the zoom lens.
24. The electronic camera as claimed in claim 17 wherein the image
provided by the first image sensor is a panoramic image.
25. The electronic camera as claimed in claim 17 wherein the first
and second images formed on the first and second image sensors have
different aspect ratios, including a panoramic aspect ratio for
the first image sensor.
26. The electronic camera as claimed in claim 25 wherein the panoramic
aspect ratio of the first image sensor is adjustable.
27. The electronic camera as claimed in claim 26 further including
a first user control for enabling a panoramic mode and a second
user control for setting a zoom position for the camera.
28. The electronic camera as claimed in claim 27 wherein, when
the panoramic mode is enabled, the setting of the second user control
engages the processing stage to modify the aspect ratio of the first
image captured by the first sensor.
29. The electronic camera as claimed in claim 16 wherein the first
lens is an additional zoom lens adjustable between a minimum focal
length and a maximum focal length to provide the first image, wherein
the maximum focal length of the first lens is less than or equal
to the minimum focal length of the zoom lens.
30. The electronic camera as claimed in claim 29 wherein the maximum
focal length of the first lens is less than the minimum focal length
of the zoom lens, thereby leaving a focal length gap therebetween,
and wherein the processing section includes an electronic zooming
capability for electronically zooming over at least a portion of
the focal length gap.
31. The electronic camera as claimed in claim 16 further comprising:
a plurality of additional image sensors for generating a corresponding
plurality of additional sensor outputs; and a plurality of additional
lenses for forming a corresponding plurality of additional images
of the scene on the plurality of additional image sensors; wherein
the control element selects either the first sensor output from
the first image sensor, the second sensor output from the second
image sensor or any one of the plurality of additional sensor outputs
from the plurality of additional image sensors, thereby providing
a selected image output.
32. The electronic camera as claimed in claim 31 wherein at least
one of the additional lenses is a zoom lens.
33. An electronic camera for producing an output image of a scene,
said electronic camera comprising: a first image sensor for generating
a first sensor output; a first lens for forming a first image of
the scene on the first image sensor; a second image sensor for generating
a second sensor output; a zoom lens pointing in the same direction
as the first lens and forming a second image of the same scene on
the second image sensor, wherein the zoom lens is adjustable between
a minimum focal length and a maximum focal length to provide the
second image; wherein the first lens is an additional zoom lens
adjustable between a minimum focal length and a maximum focal length
to provide the first image, wherein the maximum focal length of
the first lens is less than or equal to the minimum focal length
of the zoom lens; a control element for selecting either the first
sensor output from the first image sensor or the second sensor output
from the second image sensor, thereby providing a selected sensor
output; and a processing section for producing the output image
from the selected sensor output.
34. The electronic camera as claimed in claim 33 further comprising
a user control that allows a user to select a focal length and wherein
the control element is responsive to the user control for selecting
a corresponding sensor output.
35. The electronic camera as claimed in claim 34 wherein the maximum
focal length of the first lens is less than the minimum focal length
of the zoom lens, thereby leaving a focal length gap therebetween.
36. The electronic camera as claimed in claim 35 wherein the processing
section includes an electronic zooming capability for electronically
zooming over at least a portion of the focal length gap.
37. The electronic camera as claimed in claim 36 wherein the user
control allows for selecting a zoom position, whereby the zoom position
is characterized as (a) an optical focal length when it is within
the focal lengths of the first lens or within the focal lengths
of the zoom lens and (b) an electronic zoom amount when within the
gap between the maximum focal length of the first lens and the minimum
focal length of the zoom lens.
38. The electronic camera as claimed in claim 33 wherein the first
and second image sensors are differently sized and an optical path
distance between each lens and its image sensor is substantially
the same, thereby providing a pair of lens systems which have different
effective focal lengths for the same optical path distances.
39. The electronic camera as claimed in claim 33 further comprising:
a plurality of additional image sensors for generating a corresponding
plurality of additional sensor outputs; and a plurality of additional
lenses for forming a corresponding plurality of additional images
of the scene on the plurality of additional image sensors; wherein
the control element selects either the first sensor output from
the first image sensor, the second sensor output from the second
image sensor or any one of the plurality of additional sensor outputs
from the plurality of additional image sensors, thereby providing
a selected image output.
40. The electronic camera as claimed in claim 39 wherein at least
one of the additional lenses is a zoom lens.
41. An electronic camera for producing an output image of a scene,
said electronic camera comprising: a first image sensor for generating
a first sensor output; a first lens for forming a first image of
the scene on the first image sensor, wherein the first lens has
a fixed focal length, and wherein the fixed focal length of the
first lens has a 35 mm equivalent focal length of less than 25 mm;
a second image sensor for generating a second sensor output; a zoom
lens pointing in the same direction as the first lens and forming
a second image of the same scene on the second image sensor, wherein
the zoom lens is adjustable between a minimum focal length and a
maximum focal length to provide the second image; a control element
for selecting either the first sensor output from the first image
sensor or the second sensor output from the second image sensor,
thereby providing a selected sensor output; and a processing section
for producing the output image from the selected sensor output.
42. The electronic camera as claimed in claim 41 further comprising
a user control that allows a user to select a focal length and wherein
the control element is responsive to the user control for selecting
a corresponding sensor output.
43. The electronic camera as claimed in claim 42 wherein the fixed
focal length of the first lens is less than the minimum focal length
of the zoom lens, thereby leaving a focal length gap therebetween.
44. The electronic camera as claimed in claim 43 wherein the processing
section includes an electronic zooming capability for electronically
zooming over at least a portion of the focal length gap.
45. The electronic camera as claimed in claim 44 wherein the user
control allows for selecting a zoom position, whereby the zoom position
is characterized as (a) an optical focal length when it is the fixed
focal length of the first lens or within the focal lengths of the
zoom lens and (b) an electronic zoom amount when within the gap
between the fixed focal length of the first lens and the minimum
focal length of the zoom lens.
46. The electronic camera as claimed in claim 41 wherein the image
provided by the first image sensor is a panoramic image.
47. The electronic camera as claimed in claim 41 wherein the first
and second images formed on the first and second image sensors have
different aspect ratios, including a panoramic aspect ratio for
the first image sensor.
48. The electronic camera as claimed in claim 47 wherein the panoramic
aspect ratio of the first image sensor is adjustable.
49. The electronic camera as claimed in claim 48 further including
a first user control for enabling a panoramic mode and a second
user control for setting a zoom position for the camera.
50. The electronic camera as claimed in claim 49 wherein, when
the panoramic mode is enabled, the setting of the second user control
engages the processing stage to modify the aspect ratio of the first
image captured by the first sensor.
51. The electronic camera as claimed in claim 41 wherein the first
and second image sensors are differently sized and an optical path
distance between each lens and its image sensor is substantially
the same, thereby providing a pair of lens systems which have different
effective focal lengths for the same optical path distances.
52. The electronic camera as claimed in claim 41 further comprising:
a plurality of additional image sensors for generating a corresponding
plurality of additional sensor outputs; and a plurality of additional
lenses for forming a corresponding plurality of additional images
of the scene on the plurality of additional image sensors; wherein
the control element selects either the first sensor output from
the first image sensor, the second sensor output from the second
image sensor or any one of the plurality of additional sensor outputs
from the plurality of additional image sensors, thereby providing
a selected image output.
53. The electronic camera as claimed in claim 52 wherein at least
one of the additional lenses is a zoom lens.
54. The electronic camera as claimed in claim 41 wherein the minimum
focal length of the zoom lens has a 35 mm equivalent focal length
of greater than 30 mm.
55. An electronic camera for producing an output image of a scene,
said electronic camera comprising: a first image sensor for generating
a first sensor output; a first lens for forming a first image of
the scene on the first image sensor, wherein the first lens has
a fixed focal length, and wherein the fixed focal length of the
first lens has a 35 mm equivalent focal length of less than 25 mm;
a second image sensor for generating a second sensor output; a zoom
lens pointing in the same direction as the first lens and forming
a second image of the same scene on the second image sensor, wherein
the zoom lens is adjustable between a minimum focal length and a
maximum focal length to provide the second image, wherein the minimum
focal length of the zoom lens has a 35 mm equivalent focal length
of greater than 30 mm; a control element for selecting either the
first sensor output from the first image sensor or the second sensor
output from the second image sensor, thereby providing a selected
sensor output; and a processing section for producing the output
image from the selected sensor output. Digital Camera Patent DescriptionFIELD OF THE INVENTION
The present invention relates to a digital camera that produces
digital image files and, more particularly, to a digital camera
that uses multiple lenses and image sensors to provide an extended
zoom range.
BACKGROUND OF THE INVENTION
Currently, most digital cameras use a zoom lens and a single color
image sensor to capture still and motion images. The captured images
are then digitally processed to produce digital image files, which
are stored in a digital memory in the camera. The digital image
files can then be transferred to a computer, displayed, and shared
via the Internet. The digital camera can be included as part of
a mobile telephone, to form a so-called "camera phone".
The camera phone can transmit the digital image files to another
camera phone, or to service providers, via a mobile telephone network.
Small camera size and a large "optical zoom range" are
two very important features of digital cameras. Users prefer to
have a large zoom range (e.g. 5:1 or greater) rather than a limited
zoom range (e.g. 3:1 or smaller). Unfortunately, providing a large
zoom range lens, without sacrificing the quality of the captured
images, increases the size of the digital camera. Large zoom range
lenses are also more costly. Thus, there are fundamental trade-offs
between small camera size, large zoom range, and low camera cost
which must be made when designing a digital camera. With higher
cost cameras, such as single lens reflex cameras, these problems
are sometimes addressed by using multiple interchangeable zoom lenses,
such as two 3:1 zoom lenses, e.g., a 28 70 mm zoom and a 70 210
zoom. Such an option, which has its own problems in user inconvenience,
is nonetheless not available for low cost digital cameras.
The prior art of most interest can be separated into two categories:
image capture systems that use multiple lenses, usually two, having
the same focal length and image capture systems that utilize multiple
lenses, also usually two, having different focal lengths.
Addressing the first category, some digital cameras use multiple
image sensors to form a color image. In most cameras of this type,
a single lens is used to provide an image of the scene, which is
then separated into multiple colors by a prism beam splitter. Multiple
monochrome image sensors are used to capture red, green, and blue
color separation images. However, as disclosed in U.S. Pat. No.
6,611,289, entitled "Digital Cameras Using Multiple Sensors
with Multiple Lenses" and issued Aug. 26, 2003 in the name
of Yu et al., it is possible to use multiple image sensors and multiple
lenses to provide color separation. However, this patent disclosure
teaches that the lenses all have the same focal length, and are
all used together, in order to simultaneously capture the different
color components of the image
Some digital imaging systems also use multiple image sensors and
multiple lenses to capture different portions of the digital image.
Such a system is disclosed in U.S. Published Patent Application
No. US20020163582 A1, entitled "Self-calibrating, Digital,
Large Format Camera with Single or Multiple Detector Arrays and
Single or Multiple Optical Systems" and published Nov. 7, 2002
in the names of Gruber et al. In one embodiment disclosed in this
published patent application, a large format digital camera exposes
multiple detector arrays using multiple lens systems to acquire
sub-images of overlapping sub-areas of large area objects. The sub-images
are stitched together to form a large format digital macro-image.
However, all of the lenses have the same focal length, and all are
used simultaneously to capture the different sub-areas of the image.
Stereo film cameras and stereo electronic cameras are known in
the prior art. These cameras typically have two horizontally separated
lenses of the same focal length, which focus two slightly different
images of the scene onto two image sensors or two frames of film.
Such a system is disclosed in commonly assigned U.S. Pat. No. 4,989,078,
entitled "Still Video Camera for Recording Stereo Images on
a Video Disk" and issued on Jan. 21, 1991 in the name of K.
Bradley Paxton. The two images provide a so-called "stereo
pair", which simulates the slightly different perspectives
that a person's left and right eyes would see when viewing the scene.
In the aforementioned patent disclosure, the two lenses are designed
to provide the same magnification, and both are used to simultaneously
capture the left and right eye images on a pair of image sensors
in order to achieve a stereo effect.
Film cameras that use multiple lenses to capture multiple images
at the same time are also known in the prior art. For example, some
instant film cameras used to produce identification pictures can
capture four small images simultaneously on the same piece of instant
film. The four lenses in these cameras provide the same magnification,
and all are used to simultaneously capture the four images.
According to the second category of prior art, film cameras that
include two or more lenses to provide two or more different focal
lengths are also known in the prior art. For example, such cameras
can use two different fixed focal length lenses which are slid in
front of the same film plane. This provides an inexpensive "two-position
zoom" capability, that is, two fixed focal length lenses that
provide, e.g., the wide angle and telephoto angle settings of a
corresponding zoom lens. In another example, in U.S. Pat. No. 4,097,882,
entitled "Multiple Lens Camera Having Lens-position Controlled
Focal-length Adjustment" and issued Jun. 27, 1978 in the name
of Engelsmann, a "110" size pocket film camera has a carrier
mounting three or more lenses of different focal lengths that can
be selectively moved transverse to the optical axis of the camera
so as to place any one of the lenses in an operating position relative
to a film plane.
Digital cameras that include two lenses to provide two different
focal lengths are also known in the prior art. A lens turret is
popularly used to obtain multiple focal lengths in a camera. However,
in the case of a digital still camera or especially in the case
of mobile phone digital camera, lens modules are required to be
extremely small due to the limited space for the lens module. U.S.
Pat. No. 6,804,460, entitled "Lens Turret with Back Focal Length
Adjustment" and issued Oct. 12, 2004 in the names of Oshima
et al., describes a lens turret that is said to be extremely compact
and flat in size and suitable for digital still cameras and mobile
phone digital cameras. The lens turret is rotatable around an axis
and has a wide-angle lens and a telephoto-angle lens mounted thereon,
and a driving mechanism rotates the lens turret so that one of the
lenses can be set at a picture taking position opposite an image
sensor. By means of back focal length adjustment, the position of
the lens with the shorter focal length can be fixed on the lens
turret at the same level thereon as the lens with the longer focal
length.
It is also known to use a two lens arrangement in a film scanner,
where two lenses with different combinations of focal lengths are
used to capture variable sized images. For instance, in commonly
assigned U.S. Pat. No. 5,929,903, entitled "Multiposition Lens
Mechanism for a Scanner" and issued Jul. 27, 1999 in the name
of R. H. Kiesow, a removable digital camera, which is tethered to
a computer, is supported in a housing in a film scanner in the optical
path of a multiposition lens assembly having a single focal length
lens and a zoom lens. The lens assembly positions the lenses in
the optical path of the camera for scanning different sized images,
e.g., two or more film format sizes. However, these cameras, both
film and digital, that use multiple focal length lenses share the
characteristic of using only a single "sensor", that is,
a single film or a single electronic image sensor.
In U.S. Pat. No. 6,288,742, entitled "Video Camera Including
Multiple Image Sensors" and issued Sep. 11, 2001 in the names
of Ansari et el., a digital motion camera useful in teleconferencing
includes two lenses and two image sensors. As disclosed in this
patent, the first lens is an 8 mm fixed focus lens for providing
a relatively wide-angle view of a room and the second lens is a
16 mm lens with manual focus control for providing high resolution
document transmission capability. The first lens is oriented for
a room view of a conference participant to provide face-to-face
communication during a videotelephone conference, and the second
lens is oriented at a substantial angle to the first lens for viewing
a document, e.g., on a table. During a videotelephone conference,
such a camera permits fast switching between an image of the room
as seen through the first lens or an image of a document as seen
through the second lens, without the need for expensive and tediously
slow moving pan/tilt stages and/or a plurality of complete camera
units. Another camera, the Sanyo S750 UMTS cellphone camera, has
a similar kind of dual imaging capability, where an inwardly facing
VGA imager captures an image of the caller using the cellphone while
an outwardly facing 1 megapixel imager captures an image of a scene
that the caller is looking at. Such cameras, however, are not useful
in the environment of the present invention because the lenses are
not collecting images from the same scene.
In U.S. Pat. No. 4,199,785, entitled "Electronic Zoom Feature"
and issued Apr. 22, 1980 in the name of McCullough et al., a television
system employs two (or more) fixed focal length vidicon cameras,
one camera with a wide angle field of view and the other camera
with a narrow angle field of view, and an electronic zoom feature
for zooming between the two fields of view. The cameras are boresighted
such that the field of view of the smaller field camera is within,
and usually centered in the field of view of the larger field camera.
The "zoom" is accomplished by manipulating the scan generators
of the two cameras and expanding the central portion of the display
with the image from the smaller field camera as the zoom amount
is progressively increased. This system, of course, is an alternative
to a single optical zoom lens, whose usage the patent disclosure
discourages as they (optical zooms) are lower quality, more expensive
and mechanically more complex than fixed focal length lenses. However,
the inherent drawback of an electronic zoom is also low quality
since the resolution of the electronic zoom feature ordinarily is
limited by the number of scan lines available for zooming. Consequently,
this patent disclosure is devoted to controlling the scan lines
of the two vidicon cameras so as to be able to zoom without an effective
loss of resolution.
In U.S. Pat. No. 5,051,830, entitled "Dual Lens System for
Electronic Camera" and issued Sep. 24, 1991 in the name of
Hoessle, a double focal length electronic camera (used on board
a guided missile) includes a single lens system component having
a short focal length section integrated into the center of a surrounding
lens section having a long focal length, where each focal length
section has its own dedicated picture array sensor. Here too, this
lens system is a substitute for a single motor driven zoom, which
the disclosure denigrates because of size, expense, heaviness, inherent
complexity; furthermore, an optical zoom is "which is important--much
too slow with respect to its use" (col. 2, line 1 of the Hoessle
patent).
None of these prior art systems, and especially the multifocal
length prior art systems, provide a sufficiently compact, low cost,
large zoom range optical system for a small, lightweight and relatively
inexpensive consumer digital camera. As especially pointed out in
the aforementioned Hoessle patent, it is additionally desirable
to avoid the slowness so typical of zoom usage and to be able to
traverse a large zoom range quickly. What is therefore needed is
a digital camera that provides a rapidly-operating extended zoom
range without unduly increasing the size or cost of the digital
camera.
SUMMARY OF THE INVENTION
The object of this invention is to provide an extended zoom range
in a digital camera without unduly increasing the size or cost of
the camera.
Another object of this invention is to provide an extended optical
zoom range in a digital camera by means of a plurality of separate
lenses and corresponding image sensors.
Another object of this invention is to provide an extended optical
zoom range in a digital camera where the movement between user-requested
zoom positions may be undertaken in an expedited manner.
The present invention is directed to overcoming one or more of
the problems set forth above. Briefly summarized, the invention
comprises an electronic camera for producing an output image of
a scene, where the camera comprises: a first image sensor for generating
a first sensor output: a first lens for forming a first image of
the scene on the first image sensor; a second image sensor for generating
a second sensor output; a zoom lens for forming a second image of
the same scene on the second image sensor, wherein the zoom lens
is adjustable between a minimum focal length and a maximum focal
length to provide the second image; a control element for selecting
either the first sensor output from the first image sensor or the
second sensor output from the second image sensor, thereby providing
a selected sensor output; and a processing section for producing
the output image from the selected sensor output. In one variation
of this embodiment, the first lens is also a zoom lens, where the
maximum focal length of the first lens is less than or equal to
the minimum focal length of the second zoom lens.
These various aspects of the invention provide significant technical
advantages. By providing a plurality of optical image capture modalities
within a digital camera, wherein each modality includes a lens-sensor
combination with a distinctive different focal length or combination
of focal lengths (i.e., a zoom), the conflicted requirements (namely,
large size, high cost and compromised optical quality) engendered
by digital camera consumer desire for a large zoom ratio, e.g.,
10:1, can be accomplished in a smaller scale space at lower cost
with higher quality optical results than heretofore achieved.
These and other aspects, objects, features and advantages of the
present invention will be more clearly understood and appreciated
from a review of the following detailed description of the preferred
embodiments and appended claims, and by reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a block diagram of a first embodiment of a digital
camera using a fixed focal length, wide-angle lens with a first
image sensor, and a zoom lens with a second image sensor according
to the invention.
FIGS. 2A and 2B are two perspective views of the digital camera
shown in FIG. 1.
FIG. 3 depicts a flow diagram showing a method for capturing digital
images using the digital camera shown in FIG. 1.
FIG. 4 depicts a block diagram of a second embodiment of a digital
camera using a first zoom lens with a first image sensor, and a
second zoom lens with a second image sensor according to the invention.
FIGS. 5A and 5B are two perspective views of the digital camera
shown in FIG. 4.
FIG. 6 depicts a flow diagram showing a method for capturing digital
images using the digital camera shown in FIG. 4.
FIG. 7 depicts a block diagram of a third embodiment of a digital
camera using a first zoom lens with a first image sensor, a second
zoom lens with a second image sensor and a fixed focal length lens
with a third image sensor according to the invention.
FIGS. 8A and 8B are two perspective views of the digital camera
shown in FIG. 7.
FIG. 9 depicts a flow diagram showing a method for capturing digital
images using the digital camera shown in FIG. 7.
FIGS. 10A, 10B, 10C, 10D, 10E and 10F diagram the optical layout
of several embodiments of the image capture assembly used in the
cameras shown in FIGS. 1, 4, 7, 19 and 21.
FIG. 11 is a frontal view of a digital camera employing two image
capture assemblies, one fixed focal length and the other zoom, of
the type shown in FIGS. 10A 10F.
FIG. 12 is a top view of the digital camera shown in FIG. 11.
FIG. 13 is a side view of the digital camera shown in FIG. 11.
FIGS. 14A, 14B and 14C are three views of a digital camera employing
two image capture assemblies, both zoom, of the type shown in FIGS.
10A 10F.
FIGS. 15A, 15B and 15C are three views of a digital camera employing
three image capture assemblies of the type shown in FIGS. 10A 10F.
FIGS. 16A and 16B show two views of the optical relay subassembly
shown in the various embodiments of FIGS. 10A 10F for supporting
a fixed focal length lens in relation to an image sensor along a
folded optical path.
FIG. 17 shows the optical relay subassembly shown in the various
embodiments of FIGS. 10A 10F for supporting a zoom lens in relation
to an image sensor along a folded optical path.
FIGS. 18A and 18B show two imagers with different panoramic aspect
ratios and the effect obtained by changing the aspect ratio.
FIG. 19 depicts a block diagram of a further embodiment of a digital
camera using a first fixed focal length lens with a first sensor,
a second fixed focal length lens with a second sensor, and a third
fixed focal length lens with a third sensor.
FIG. 20 depicts a flow diagram showing a method for capturing digital
images using the digital camera shown in FIG. 19.
FIG. 21 depicts a block diagram of a further embodiment of a digital
camera using a first lens with a first sensor having pixels of one
size. e.g., three micron pixels, and a second lens with a second
sensor having pixels of another size, e.g., five micron pixels.
FIG. 22 is a diagram useful for explaining an express zooming feature.
FIGS. 23A and 23B are perspective views of the front and back of
a cell phone including a camera with multiple lenses and multiple
sensors.
FIGS. 24A and 24B are two views of the image capture assembly used
in the cell phone shown in FIGS. 23A and 23B.
DETAILED DESCRIPTION OF THE INVENTION
Because digital cameras employing imaging devices and related circuitry
for signal processing are well known, the present description will
be directed in particular to elements forming part of, or cooperating
more directly with, apparatus in accordance with the present invention.
Elements not specifically shown or described herein may be selected
from those known in the art. Certain aspects of the embodiments
to be described may be provided in software. Given the system as
shown and described according to the invention in the following
materials, software not specifically shown, described or suggested
herein that is useful for implementation of the invention is conventional
and within the ordinary skill in such arts.
Each of the several embodiments of the present invention include
an image capture assembly having multiple lenses and multiple image
sensors mounted within a digital camera in order to provide an extended
zoom range. This can reduce the cost and size of the camera, and
improve its optical performance, compared with a camera having a
single sensor and a large range zoom lens (e.g. having a 10:1 zoom
range). While not in an exactly coaxial arrangement with respect
to each other, the multiple lenses and sensors are generally aligned
with respect to each other so as to be viewing substantially the
same object, albeit with different fields of view. Each image capture
assembly comprises two or more optical relay subassemblies having
a lens and an image sensor disposed at opposing ends thereof and
a folded optical path for directing the light from the lens to the
sensor. This configuration can further reduce the size of the optical
components, thereby enabling the design and manufacture of a very
thin and compact camera. While the folded optics are used in many
of the preferred embodiments, a folded optical path is not generally
necessary for practice of the invention. This is particularly true
for the wide angle optical subassemblies since the focal length
of such wide angle lenses is very short to begin with. Also, the
size of the sensor, and consequently the size of the image that
must be produced to fill the sensor, may be small enough to reduce
the focal length to an acceptable front-to-back dimension--even
for normal and short telephoto focal lengths.
In each embodiment, the camera includes a control element for selecting
either the first sensor output from the first image sensor or a
sensor output from one of the other image sensors, thereby providing
a selected sensor output that may be provided to a processing section
in the camera for producing an output image. Moreover, each embodiment
includes some type of user control that allows a user to select
a focal length, either directly or via some marking (e.g., "panoramic"
or "portrait") indicative of a focal length; the aforementioned
control element is then responsive to the user control for selecting
a corresponding sensor output. In some embodiments, a single "zoom
lens" user control is used, e.g., where the "wide"
setting selects a wide angle fixed focal length lens and the "tele"
setting(s) select various positions of a zoom lens. The user control
output is then provided to the control element, which selects the
image sensor that is used to produce the output image. When the
selected sensor is for the zoom lens, the user control (or the control
element) also enables the zoom and focus motors for the zoom lens
to drive the zoom lens to the selected focal length. In addition,
digital zooming may be used to zoom "up" from the wide
angle setting to the minimum focal length setting of the zoom lens.
All this, of course, may be transparent to the user, who simply
manipulates the "zoom lens" user control between the "wide"
and "tele" settings.
Referring first to FIGS. 10A 10F, several diagrams are shown of
the optical layout of several embodiments of an image capture assembly
1, which is included within the various embodiments of a digital
camera (which will be described later). These diagrams include the
optical relay subassemblies 1a, 1b and 1c containing the aforementioned
folded optical elements. In each of the FIGS. 10A 10F, a circle
1d delineates an optical profile of a front surface of a digital
camera through which the respective lenses protrude. The optical
relay subassemblies 1a, 1b and 1c are folded behind the lenses and,
as will be described, covered by the front surface of the camera.
In a first embodiment of the present invention, a digital camera
employs a first fixed focal length wide angle lens 2 with a first
image sensor 12, and a zoom lens 3 with a second image sensor 14.
In the first embodiment as shown in FIG. 10A, an image capture assembly
1 includes the first lens 2 and the first image sensor 12 mounted
at opposing ends of a first optical relay subassembly 1a having
a folded optical path arranged between the first image sensor 12
and the lens 2. The first lens 2, which preferably is a fixed focal
length wide angle lens, forms a first image of a scene on the first
image sensor 12. The image capture assembly 1 also includes the
zoom lens 3 and the second image sensor 14 mounted at opposing ends
of a second optical relay subassembly 1b having a folded optical
path arranged between the second image sensor 14 and the zoom lens
3. The zoom lens 3, which has a range of focal lengths adjustable
between a minimum focal length and a maximum focal length, forms
a second image of the scene on the second image sensor 14. In this
embodiment, the first lens 2 is a wide angle lens having a focal
length less, and preferably substantially less, than the minimum
focal length of the zoom lens 3.
In a second embodiment of the present invention, a digital camera
employs a first zoom lens 3 with an image sensor 14, and a second
zoom lens 4 with an image sensor 16. In the second embodiment as
shown in FIG. 10B, the image sensor 14 will be characterized as
the first image sensor 14 and the image sensor 16 will be characterized
as the second image sensor 16. Accordingly, the image capture assembly
1 includes the first zoom lens 3 and the first image sensor 14 mounted
at opposing ends of a first optical relay subassembly 1b having
a folded optical path arranged between the first image sensor 14
and the first zoom lens 3. The first zoom lens 3, which has a range
of focal lengths adjustable between a minimum focal length and a
maximum focal length, forms a first image of the scene on the first
image sensor 14. The image capture assembly 1 also includes the
second zoom lens 4 and the second image sensor 16 mounted at opposing
ends of a second optical relay subassembly 1c having a folded optical
path arranged between the second image sensor 16 and the zoom lens
4. The zoom lens 4, which has a range of focal lengths adjustable
between a minimum focal length and a maximum focal length, forms
a second image of the scene on the second image sensor 16. In this
embodiment, the maximum focal length of the first zoom lens 3 is
less than or equal to the minimum focal length of the second zoom
lens 4.
In a third embodiment of the present invention, the digital camera
employs a first zoom lens 3 with an image sensor 14, a second zoom
lens 4 with an image sensor 16 and a fixed focal length, wide angle
lens 2 with an image sensor 12. In the third embodiment as shown
in FIG. 10C, the image sensor 14 will be characterized as the first
image sensor 14, the image sensor 16 will be characterized as the
second image sensor 16, and the image sensor 12 will be characterized
as the third image sensor. Accordingly, the first zoom lens 3 forms
a first image of the scene on the first image sensor 14, and the
second zoom lens 4 forms a second image of the scene on the second
image sensor 16, similarly to what is shown and described in FIG.
10B. In addition, a third lens, the fixed focal length lens 2, and
the third image sensor 12 are mounted at opposing ends of a third
optical relay subassembly 1a having a folded optical path arranged
between the third image sensor 12 and the third lens 2. In this
embodiment, the third lens 2 preferably is a fixed focal length
wide angle lens having a focal length less, and preferably substantially
less, than the minimum focal length of the first zoom lens 3, and
the maximum focal length of the first zoom lens 3 is less than or
equal to the minimum focal length of the second zoom lens 4.
In a fourth embodiment, the digital camera employs a first fixed
focal length lens 2a with a first image sensor 12a, and a second
fixed focal length lens 2b with a second image sensor 12b. In the
fourth embodiment as shown in FIG. 10D, an image capture assembly
1 includes the first fixed focal length lens 2a and the first image
sensor 12a mounted at opposing ends of a first optical relay subassembly
1a(1) having a folded optical path arranged between the first image
sensor 12a and the first fixed focal length lens 2a. The image capture
assembly 1 also includes the second fixed focal length lens 2b and
the second image sensor 12b mounted at opposing ends of a second
optical relay subassembly 1a(2) having a folded optical path arranged
between the second image sensor 12b and the second fixed focal length
lens 2b. In this embodiment, the first fixed focal length lens 2a
is preferably a wide angle lens and the second fixed focal lens
2b is a telephoto lens.
In a fifth embodiment, the digital camera employs a first fixed
focal length lens 2a with a first image sensor 12a, a second fixed
focal length lens 2b with a second image sensor 12b and a third
fixed focal length lens 2c with a third image sensor 12c. In the
fifth embodiment as shown in FIG. 10E, the first lens 2a and the
first image sensor 12a are mounted at opposing ends of a first optical
relay subassembly 1a(1) having a folded optical path arranged between
the first image sensor 12a and the first lens 2a. The first lens
2a, which preferably is a fixed focal length ultra wide angle lens,
forms a first image of the scene on the first image sensor 12a.
The second lens 2b and the second image sensor 12b are mounted at
opposing ends of a second optical relay subassembly 1a(2) having
a folded optical path arranged between the second image sensor 12b
and the second lens 2b. The second lens 2b, which preferably is
a fixed focal length medium angle lens, forms a second image of
the scene on the second image sensor 12b. The third lens 2c and
the third image sensor 12c are mounted at opposing ends of a third
optical relay subassembly 1a(3) having a folded optical path arranged
between the third image sensor 12c and the third lens 2c. The third
lens 2c, which preferably is a fixed focal length narrow angle (telephoto)
lens, forms a third image of the scene on the third image sensor
12c.
In a sixth embodiment, the digital camera employs a first fixed
focal length lens 2a with a first image sensor 12a, a second fixed
focal length lens 2b with a second image sensor 12b, a third fixed
focal length lens 2c with a third image sensor 12c, and a fourth
fixed focal lens 2d with a fourth image sensor 12d. In the sixth
embodiment as shown in FIG. 10F, the first lens 2a and the first
image sensor 12a are mounted at opposing ends of a first optical
relay subassembly 1a(1) having a folded optical path arranged between
the first image sensor 12a and the first lens 2a. The first lens
2a, which preferably is a fixed focal length ultra wide angle lens,
forms a first image of the scene on the first image sensor 12a.
The second lens 2b and the second image sensor 12b are mounted at
opposing ends of a second optical relay subassembly 1a(2) having
a folded optical path arranged between the second image sensor 12b
and the second lens 2b. The second lens 2b, which preferably is
a fixed focal length medium angle lens, forms a second image of
the scene on the second image sensor 12b. The third lens 2c and
the third image sensor 12c are mounted at opposing ends of a third
optical relay subassembly 1a(3) having a folded optical path arranged
between the third image sensor 12c and the third lens 2c. The third
lens 2c, which preferably is a fixed focal length narrow angle (telephoto)
lens, forms a third image of the scene on the third image sensor
12c. The fourth lens 2d and the fourth image sensor 12d are mounted
at opposing ends of a fourth optical relay subassembly 1a(4) having
a folded optical path arranged between the fourth image sensor 12d
and the fourth lens 2d. The fourth lens 2d, which preferably is
a fixed focal length very narrow angle (long telephoto) lens, forms
a fourth image of the scene on the fourth image sensor 12d.
These embodiments may clearly be carried as far as possible--i.e.,
more than four lenses, four sensors and four optical relay subassemblies--as
long as their arrangement is practically possible within the spatial
confines of the digital camera.
FIG. 11 provides a spatial layout of a digital camera, showing
how the various components described in FIG. 10A fits within the
confined space of the digital camera 10A. For example, FIGS. 11
and 12 show how the image capture assembly 1 is arranged within
the width-wise dimension 201 of a digital camera 10A for the first
embodiment shown in FIG. 10A. FIG. 11 is a frontal view of the digital
camera 10A showing how the fixed focal length lens subassembly 1a
and the zoom lens subassembly 1b are positioned to one side of the
lenses 2 and 3 beneath an electronic flash 48. A battery compartment
204 is located on the other side of the lenses 2 and 3. FIG. 12
is a top view of the digital camera 10A taken along lines 12--12
in FIG. 11, and further shows the location of a removable memory
card 54 and a color LCD image display 70. FIG. 13 is a side view
of the digital camera 10A taken along the lines 13--13 in FIG. 12,
and further shows the vertical spacing of the fixed focal length
lens subassembly 1a, the zoom lens subassembly 1b, and the flash
48. It is particularly noteworthy that the folded optics employed
in the subassemblies 1a and 1b enable the image capture assembly
1 to fit within a compact front to rear dimension 210 of the camera
10A. It is also noteworthy that the embodiment of FIG. 10D, employing
two fixed focal length lens subassemblies 1a(1) and 1a(2), could
be substituted into the arrangement shown in FIG. 1, thereby enabling
a camera with even a lesser width-wise dimension 201.
FIGS. 14A, 14B, and 14C show an arrangement of the components in
the second embodiment shown in FIG. 10B within the digital camera
10B, where FIG. 14B is a top view taken along the lines 14B--14B
in FIG. 14A, and FIG. 14C is a side view taken along the lines 14C--14C
in FIG. 14B. Note that, because of the larger size of the second
zoom subassembly 1c, the spatial relationship of the components
has been rearranged. The battery compartment 204 has now been moved
under the flash 48, thereby freeing up more room on the opposite
side of the lenses 3 and 4 for the folded optics. Similarly, FIGS.
15A, 15B and 15C show an arrangement of the components in the third
embodiment shown in FIG. 10C, where FIG. 15B is a top view taken
along the lines 15B--15B in FIG. 15A, and FIG. 15C is a side view
taken along the lines 15C--15C in FIG. 15B. It should be clear from
these illustrations that the front-to-back folding of the optical
systems offers significant advantages over the prior art, and over
even such an optical system as shown in the aforementioned Hoessle
reference (U.S. Pat. No. 5,051,830), which shows two optical paths
integrated into one system. The narrow front-to-back dimension 210
produces a pocket-sized camera, and in the context of this invention,
a pocket-sized camera with zoom, or zoom-like, features.
In each of the above embodiments, the image capture assembly may
be integrated into the manufacture of the digital camera or it may
stand alone as a fungible component that is, e.g., separately manufactured
and supplied to a camera manufacturer for insertion into the camera.
The image capture assembly may further include a control section
for driving the sensors and selecting either the first sensor output
from the first image sensor or a sensor output from one of the other
image sensors. In addition, in some embodiments the sensors in the
image capture assembly may be positioned next to each other on a
common circuit board assembly, or may be packaged in a common integrated
circuit package, and the lenses in the image capture assembly may
be provided in a common lens assembly that mounts onto the circuit
board or the integrated circuit package. In some preferred embodiments,
the separate imaging arrays are part of the same CCD or CMOS integrated
circuit, and the two lenses are assembled together and aligned with
the sensor package.
Moreover, in the foregoing embodiments providing a plurality of
three or more image sensors for generating three or more sensor
outputs, and a plurality of three or more lenses for forming a corresponding
three or more images of the scene on the corresponding three or
more image sensors, the lenses employed may be provided in different
spatial arrangements within the front optical profile 1d of the
digital camera. Where three lenses are employed, the three lenses
may be provided within the optical profile 1d on the camera in a
triangular arrangement, as shown in FIG. 10C or 10E. Where four
lenses are employed, the four lenses may be provided within the
optical profile 1d on the camera in a rectangular arrangement as
shown in FIG. 10F.
Furthermore, in each of the embodiments, when the fixed, or maximum,
focal length of one lens is less than the minimum focal length of
the next greater focal length lens, there is a focal length gap
left between the two lenses. In that case, the processing section
in the camera may include an electronic zooming capability for electronically
zooming over at least a portion of the focal length gap. Consequently,
if a single "zoom lens" user control is used, a transition
between some settings of the user control will cause a zoom lens
to move to a particular optical zoom position, while a transition
between other settings of the user control will cause the processor
to digitally zoom up from an optical image output of the wide angle
lens. For example, where the electronic camera provides a zoom setting
over a range including a wide angle optical focal length and a group
of optical focal lengths provided by at least one tele zoom lens,
at least some of the intervening focal lengths in the gap between
the wide angle focal length and the zoom focal lengths of the tele
zoom are provided by electronically zooming up from an image captured
at the wide angle optical focal length. Furthermore, the wide angle
optical focal length that is being zoomed can be provided by the
maximum focal length of another (wide angle) zoom lens.
FIGS. 16A and 16B show two views of the optical relay subassembly
1a shown in FIGS. 10A, and 10C 10F for supporting a fixed focal
length lens 2 in relation to an image sensor 12 along a folded optical
path. FIG. 16A shows a lens barrel 6a for supporting the outer objective
of the fixed focal length lens 2, the image sensor 12 and associated
relay lens components 7a in an optical path that is folded by a
mirror prism 8a. In addition, the lens barrel 6a supports an aperture,
shutter assembly 9a in the optical path. FIG. 16B is a view taken
along the line 16B--16B in FIG. 16A, showing an appearance of the
optical subassembly 1a from the face of the camera (as shown generally
in FIG. 10A). FIG. 17 shows the optical relay subassembly 1b (or
1c) shown in FIGS. 10A, 10B and 10C for supporting a zoom lens 3
(or 4) in relation to an image sensor 14 (or 16) along a folded
optical path. FIG. 17 shows a fixture 6b for supporting the outer
objective of the zoom lens 3 (or 4), the second image sensor 14
(or third image sensor 16), and movable relay (zoom) lens components
7b in an optical path that is folded by a mirror prism 8b. In addition,
the fixture 6b supports an aperture shutter assembly 9b in the optical
path. FIG. 17 also shows the zoom and focus motors 5a for controlling
the movement of the lens components 7b.
FIG. 1 depicts a block diagram of a digital camera 10A according
to the first embodiment of the present invention. The digital camera
10A is a portable battery operated device, small enough to be easily
handheld by a user when capturing and reviewing images. In the preferred
embodiment, the digital camera 10A produces still digital images
that are stored on a removable memory card 54. The digital camera
may produce motion digital images, either exclusively or in addition
to the still images, that are also stored on the memory card 54.
The digital camera 10A includes the aforementioned image capture
assembly 1 described in FIGS. 10A and 11, comprising a fixed focal
length lens 2 that focuses an image of a scene (not shown) onto
a first image sensor 12, and a zoom lens 3 which focuses an image
of the scene onto a second image sensor 14. The image capture assembly
1 provides a first image output 12e from the first image sensor
12 and a second image output 14e from the second image sensor 14.
In one preferred embodiment, the images sensors 12 and 14 are identical
in size, both as to aspect ratio and pixel size, the lens 2 is an
ultra-wide angle lens with a "35 mm film equivalent focal length"
of 22 mm (written as 22 mm equiv., where 22 mm is the focal length
of a 35 mm photographic film camera that provides the same field
of view as the fixed lens 2 provides to the image sensor 12, as
defined in the ANSI/I3A IT10.7000-2004 standard available from the
American National Standards Institute, Inc., New York, N.Y.), and
the zoom lens 3 is a 3:1 zoom lens having a 38 mm 114 mm equiv.
focal length range.
The 35 mm film equivalent focal length (f.l.) can be calculated
using the formula: 35 mm-equiv. f.l=(actual lens f.l. (in mm).times.43.27
mm)/(diagonal sensor focal plane distance (in mm)). For example,
if the image sensor uses a 1/2'' type optical format, it has a focal
plane of 6.4 mm (width).times.4.8 mm (height), with a diagonal distance
of 8.0 mm. If this type of image sensor is used with a lens having
an actual focal length of 4.0 mm, the 35 mm equiv. focal length
is 22 mm.
Because the focal length of the fixed lens 2 generates an ultra-wide
angle field of view, e.g., 22 mm equiv., it has a fixed focus set
to a distance near the lens hyperfocal distance of 8 feet, so that
objects from 4 feet to infinity are in focus. Therefore, fixed lens
2 does not need to include a focus adjustment. The fixed focal length
lens 2 includes an adjustable aperture and shutter assembly 9a (as
shown FIGS. 16A and 16B) to control the exposure of the image sensor
12. The zoom lens 3 is controlled by zoom and focus motors 5a and
an adjustable aperture and shutter assembly 9b (as shown in FIG.
17) to control the exposure of the image sensor.
In a preferred embodiment, the image sensors 12 and 14 are single-chip
color Megapixel CCD sensors, using the well-known Bayer color filter
pattern to capture color images. The image sensors 12 and 14 can
have, for example, a 4:3 image aspect ratio and a total of 3.1 effective
megapixels (million pixels), with 2048 active columns of pixels.times.1536
active rows of pixels. The image sensors 12 and 14 can use a 1/2''
type optical format, so that each pixel is approximately 3.1 microns
tall by 3.1 microns wide. A control processor and timing generator
40 controls the first image sensor 12 by supplying signals to clock
drivers 13, and controls the second image sensor 14 by supplying
signals to clock drivers 15.
The control processor and timing generator 40 also controls the
zoom and focus motors 5a, and a flash 48 for emitting light to illuminate
the scene. The control processor and timing generator 40 also receives
signals from automatic focus and automatic exposure detectors 46.
In an alternative embodiment, instead of using the automatic focus
and automatic exposure detectors 46, the image sensor 14 could be
used to provide exposure detection and "through-the-lens"
autofocus, as described in commonly-assigned U.S. Pat. No. 5,668,597,
which is entitled "Electronic Camera with Rapid Automatic Focus
of an Image upon a Progressive Scan Image Sensor" and which
issued Sep. 26, 1997 in the names of Kenneth A. Parulski, Masaki
Izumi, Seiichi Mizukoshi and Nobuyuki Mori, and which is incorporated
herein by reference. User controls 42 are used to control the operation
of the digital camera 10A.
The analog output signal 12e from the first image sensor 12 is
amplified by a first analog signal processor (ASP1) 22 and provided
to a first input of a control element 34, e.g., an analog multiplexer
control element. The analog output signal 14e from the second image
sensor 14 is amplified by a second analog signal processor (ASP
2) 24 and provided to a second input of the control element 34,
that is, the analog multiplexer control element. The function of
the control element 34 is to select either the first sensor output
12e from the first image sensor 12 or the second sensor output 14e
from the second image sensor 14, thereby providing a selected sensor
output from the image capture assembly 1.
The control processor and timing generator 40 controls the analog
multiplexer control element 34 in order to provide the output of
either the (ASP1) 22 or the (ASP 2) 24 to an analog-to-digital (A/D)
converter circuit 36. The digital data provided by the A/D converter
36 is stored in a DRAM buffer memory 38 and subsequently processed
by an image processor 50. The processing performed by the image
processor 50 is controlled by firmware stored in a firmware memory
58, which can be flash EPROM memory. The processor 50 processes
the input digital image file, which is buffered in a RAM memory
56 during the processing stage.
In an alternative embodiment (not shown), two A/D converter circuits
are connected to the outputs of ASP1 (22) and ASP 2 (24) and the
analog mux 34 is not used. Instead, a digital multiplexer is used
to select which one of the outputs of the two A/D converters is
connected to the DRAM buffer memory 38.
The processed digital image file is provided to a memory card interface
52, which stores the digital image file on the removable memory
card 54. Removable memory cards 54 are one type of removable digital
image storage medium, and are available in several different physical
formats. For example, the removable memory card 54 can include (without
limitation) memory cards adapted to well-known formats, such as
the Compact Flash, SmartMedia, MemoryStick, MMC, SD, or XD memory
card formats. Other types of removable digital image storage media,
such as magnetic hard drives, magnetic tape, or optical disks, can
alternatively be used to store the still and motion digital images.
Alternatively, the digital camera 10A can use internal non-volatile
memory (not shown), such as internal Flash EPROM memory to store
the processed digital image files. In such an embodiment, the memory
card interface 52 and the removable memory card 54 are not needed.
The image processor 50 performs various housekeeping and image
processing functions, including color interpolation followed by
color and tone correction, in order to produce rendered sRGB image
data. The rendered sRGB image data is then JPEG compressed and stored
as a JPEG image file on the removable memory card 54. The rendered
sRGB image data may also be provided to a host PC 66 via a host
interface 62 communicating over a suitable interconnection, such
as a SCSI connection, a USB connection or a Firewire connection.
The JPEG file uses the so-called "Exif" image format defined
in "Digital Still Camera Image File Format (Exif)" version
2.1, July 1998 by the Japan Electronics Industries Development Association
(JEIDA), Tokyo, Japan. This format includes an Exif application
segment that stores particular image metadata, including the date/time
the image was captured, as well as the lens f/number and other camera
settings.
It should be noted that the image processor 50, while typically
a programmable image processor, can alternatively be a hard-wired
custom integrated circuit (IC) processor, a general purpose microprocessor,
or a combination of hard-wired custom IC and programmable processors.
The image processor 50 also creates a low-resolution "thumbnail"
size image, which can be created as described in commonly-assigned
U.S. Pat. No. 5,164,831, entitled "Electronic Still Camera
Providing Multi-Format Storage Of Full And Reduced Resolution Images"
and issued in the name of Kuchta, et al., the disclosure of which
is herein incorporated by reference. After images are captured,
they can be quickly reviewed on a color LCD image display 70 by
using the thumbnail image data. The graphical user interface displayed
on the color LCD image display 70 is controlled by the user controls
42.
In some embodiments of the present invention, the digital camera
10A is included as part of a camera phone. In such embodiments,
the image processor 50 also interfaces to a cellular processor 90,
which uses a cellular modem 92 to transmit digital images to a cellular
network (not shown) using radio frequency transmissions via an antenna
94. In some embodiments of the present invention, the image capture
assembly 1 may be an integrated assembly including the lenses 2
and 3, the image sensors 12 and 14, and zoom and focus motors 5a.
In addition, the clock drivers 13 and 15, as well as the analog
signal processors 22 and 24, the analog mux 34, and the A/D converter
36, may be part of the integrated assembly.
FIGS. 2A and 2B show perspective views of the digital camera 10A
described in relation to FIG. 1. FIG. 2A is a frontal view of the
camera 10A, showing the fixed focal length lens 2, the zoom lens
3 and the flash 48. The fixed focal length lens is preferably an
ultra wide angle lens; a suitable lens has a 22 mm equiv. focal
length and an f/2 maximum aperture. The zoom lens is preferably
an ultra-thin lens, e.g., a prism lens; a suitable zoom would be
a 3:1 zoom ratio lens, such as a 38 114 mm equiv. focal length zoom
lens. A prism lens is a lens configuration, such as shown in FIGS.
16A, 16B, and 17, that incorporates a prism 8a, 8b for folding the
optical path, thereby creating a very compact optical construction.
Clearly, other lens focal lengths and lens type constructions are
within the scope of the invention. FIG. 2B is a rear view of the
camera 10A, showing the color (LCD) image display 70 and a number
of user controls 42, including a shutter button 42a for enabling
an image capture sequence, a panoramic button 42b for enabling a
panoramic mode, a zoom button 42c for enabling a selection of a
zoom setting, and a multi-position selector 42d for navigating through
images, menu choices and the like that are displayed on the color
LCD display 70.
In a further embodiment, the aspect ratio of the image provided
by the fixed focal length lens 2 and the image sensor 12 may be
different than the aspect ratio of the image provided by the zoom
lens 3 and the image sensor 14. For example the image sensor 12
can have a 16:9 image aspect ratio, with 2730 active columns of
pixels.times.1536 active rows of pixels, for a total of 4.2 effective
megapixels. Consequently, the display 70 is preferably a wide aspect
ratio (e.g., 16:9) format display. As shown in FIGS. 18A and 18B,
the aspect ratio of the image sensor 12 (shown in broken line) may
represent a panoramic image 18 (e.g., a 16:9 aspect ratio panoramic
image as shown in FIG. 18A) and the aspect ratio of the image sensor
14 (shown in broken line) may represent a typical television aspect
ratio image 19 (e.g., a 4:3 aspect ratio image as shown in FIG.
18B). In this case, the user control 42 may input user commands
to the control processor and timing generator 40 for changing the
aspect ratio of the stored images which are provided by the image
sensor 12 in order to obtain a variable panoramic effect that transitions
from the wide angle of the lens 2 toward a narrower angle approaching
the effect of the 4:3 aspect ratio of the zoom lens 3. This is accomplished
by cropping the image data which has been stored in DRAM buffer
memory 38, so that only a center subset of the image data provided
from the image sensor 12 is processed by image processor 50 and
stored on removable memory card 54. For example, and as shown in
FIG. 18A, the vertical margins 18b of the image may be continuously
adjusted, from the normal 16:9 aspect ratio to a wider aspect ratio
image, by pressing on the wide control section of the zoom button
42c. In response, the top and bottom of the image in DRAM buffer
memory 38 is cropped by image processor 50 to produce increasingly
wider aspect ratios, such as 17:9, 18:9 (2:1), 19:9, etc. image
aspect ratios. Alternatively, the horizontal margins 18a of the
image may be adjusted, from the normal 16:9 aspect ratio to a narrower
aspect ratio image by instead pressing on the telephoto control
section of the zoom button 42c. In response, the left and right
sides of the image in DRAM buffer memory 38 are cropped by image
processor 50 to produce increasingly narrower aspect ratios, such
as 15:9, 14:9, 3:2, etc. image aspect ratios. In this manner, a
variable panoramic effect may be digitally effected using the image
data from the first image sensor 12.
FIG. 3 depicts a flow diagram showing a method for capturing digital
images using the digital camera of FIG. 1. In lens setting block
100, when the camera 10A is turned on using a power switch (not
shown), the zoom lens 3 is set to a default position, which is preferably
a wide angle position (e.g., the 38 mm position). In panoramic decision
block 102, if the user presses the panoramic button 42b (i.e., a
yes response to block 102), the control processor and timing generator
40 controls the analog multiplexer 34 to use (first sensor block
114) the output of the analog signal processor (ASP1) 22, so that
the output of the first image sensor 12 is provided to the A/D converter
36. Thereupon, a preview image from the image sensor 12 is captured
and displayed in preview block 116. If the zoom button is pressed
at this point (having specified that the wide angle image is being
used), the aspect ratio of the image is modified in the aspect ratio
adjustment block 118 so as to obtain a variable panoramic effect
from the wide angle of the lens 2. Then, if the shutter button is
pressed, a still image is captured in capture block 120 using the
output of the first sensor 12.
In panoramic decision block 102, if the user does not press the
panoramic button 42b (i.e., a no response to block 102), the control
processor and timing generator 40 controls the analog multiplexer
34 to use (second sensor block 104) the output of the analog signal
processor (ASP2) 24, so that the output of the second image sensor
14 is provided to A/D converter 36. Thereupon, a preview image from
the image sensor 14 is captured and displayed in preview block 106.
If the zoom button is pressed at this point (having specified that
the zoom image is being used), the position of the zoom lens is
adjusted in the zoom adjustment block 108 so as to obtain a zooming
effect from the minimum focal length to the maximum focal length
of the zoom lens 3. Then, if the shutter button is pressed, a still
image is captured in capture block 110 using the output of the second
sensor 14.
In a further variation on this embodiment, after the panoramic
button 42b is pressed (having thus specified that the wide angle
image is being used) or if the zoom button 42c is pressed without
first pressing the panoramic button 42b (having thus specified that
the zoom image is being used), the image sensor that is not being
used may optionally be powered down (in the power down block 112)
to reduce the power drain and conserve the battery supply.
FIG. 4 depicts a block diagram of a digital camera 10A according
to the second embodiment of the present invention. In the second
embodiment, a digital camera 10B includes two zoom lenses, each
providing an image to a corresponding image sensor. The first zoom
lens 3 is controlled by zoom and focus motors 5a, and provides an
image to the first image sensor 14. The second zoom lens 4 is controlled
by zoom and focus motors 5b, and provides an image to the second
image sensor 16. A user zoom control on the camera selects, depending
on its setting, either the output 14e of the first image sensor
14 or the output 16e of the second image sensor 16. The remaining
aspects of the digital camera 10B are similar to the digital camera
10A shown in FIG. 1, and retain the same reference characters. Reference
is therefore made to FIG. 1 for further description of these aspects
of the digital camera 10B.
FIGS. 5A and 5B show perspective views of the digital camera 10B
described in relation to FIG. 4. FIG. 5A is a front view of the
camera 10B, showing the first zoom lens 3, the second zoom lens
4 and the flash 48. The first zoom lens 3 is preferably an ultra-thin
lens, e.g., a prism lens; a suitable zoom would be an approximately
3:1 zoom ratio lens, such as a 38 114 mm equiv. focal length zoom
lens. The second zoom lens 4 is preferably another ultra-thin lens,
e.g., a prism lens; a suitable zoom would be an approximately 3:1
zoom ratio lens, such as a 133 380 mm equiv. focal length zoom lens.
Preferably a total zoom ratio of approximately 10:1 may be obtained
from the usage of both of the zoom lens. Furthermore, in a preferred
embodiment, and since the motorized zooming is typically done between
discrete zoom steps rather than continuously, the small gap in focal
length between first zoom lens 3 and the second zoom lens 4 is equivalent
to a focal length zoom step. Clearly, other lens focal lengths and
lens type constructions are within the scope of the invention.
FIG. 5B is a rear view of the camera 10B, and similar in all respects,
except for the lack of the panoramic button 42b, to FIG. 2B. Since
neither imager has a panoramic aspect ratio, the display 70 is preferably
a 4:3 aspect ratio display.
FIG. 6 depicts a flow diagram showing a method for capturing digital
images using the digital camera of FIG. 4. In lens setting block
100, when the camera 10B is turned on using a power switch (not
shown), the first zoom lens 3 is set to a default position, which
is preferably a wide angle position (e.g., the 38 mm position).
In zoom position block 122, if the user presses the zoom button
42c and obtains a position beyond X (i.e., something greater than
125 mm and therefore a yes response to block 122), the control processor
and timing generator 40 controls the analog multiplexer 34 to use
(second sensor block 134) the output of the analog signal processor
(ASP1) 24, so that the output of the second image sensor 16 is provided
to the A/D converter 36. Thereupon, a preview image from the image
sensor 16 is captured and displayed in preview block 136. Then,
if the shutter button is pressed, a still image is captured in capture
block 140 using the output of the second sensor 16. If the zoom
button is pressed at this point in the zoom button block 138, control
is returned to the zoom position block 122.
In zoom position block 122, if the user presses the zoom button
42c and obtains a position less than a position X (i.e., something
less than 125 mm and therefore a no response to block 122), the
control processor and timing generator 40 controls the analog multiplexer
34 to use (first sensor block 124) the output of the analog signal
processor (ASP2) 22, so that the output of the first image sensor
14 is provided to the A/D converter 36. Thereupon, a preview image
from the image sensor 14 is captured and displayed in preview block
126. Then, if the shutter button 42a is pressed, a still image is
captured in capture block 130 using the output of the first sensor
16. If the zoom button is pressed at this point in the zoom button
block 128, control is returned to the zoom position block 122, and
the process is repeated.
FIG. 7 depicts a block diagram of a digital camera 10C according
to the third embodiment of the present invention. In the third embodiment,
a digital camera 10C includes two zoom lenses 3 and 4 and a fixed
focal length lens 2, each providing an image to a corresponding
image sensor. The first zoom lens 3 is controlled by zoom and focus
motors 5a, and provides an image to the first image sensor 14. The
second zoom lens 4 is controlled by zoom and focus motors 5b, and
provides an image to the second image sensor 16. The fixed focal
length lens 2 provides an image to the third image sensor 12. A
user zoom control on the camera selects, depending on its setting,
either the output 14e of the first image sensor 14, the output 16e
of the second image sensor 16, or the output 12e of the third image
sensor 12. The remaining aspects of the digital camera 10C are similar
to the digital camera 10B shown in FIG. 4, and retain the same reference
characters. Reference is therefore made to FIG. 4 for further description
of these aspects of the digital camera 10C.
FIGS. 8A and 8B show perspective views of the digital camera 10C
described in relation to FIG. 7. FIG. 8A is a frontal view of the
camera 10C, showing the first zoom 3, the second zoom lens 4, the
fixed focal length lens 2 and the flash 48. The first zoom lens
3 is preferably an ultra-thin lens, e.g., a prism lens; a suitable
zoom would be an approximately 3:1 zoom ratio lens, such as a 38
114 mm equiv. focal length zoom lens. The second zoom lens 4 is
preferably another ultra-thin lens, e.g., a prism lens; a suitable
zoom would be an approximately 3:1 zoom ratio lens, such as a 133
380 mm equiv. focal length zoom lens. Preferably a total zoom ratio
of approximately 10:1 may be obtained from the usage of both of
the zoom lens. Furthermore, in a preferred embodiment, the small
gap in focal length between first zoom lens 3 and the second zoom
lens 4 is equivalent to a focal length zoom step. The fixed focal
length lens is preferably an ultra wide angle lens; a suitable lens
has a 22 mm equiv. focal length and an f/2 maximum aperture. Clearly,
other lens focal lengths and lens type constructions are within
the scope of the invention.
FIG. 8B is a rear view of the camera 10C, and similar in all respects
to FIG. 2B. In a further (optional) variation of the third embodiment,
the aspect ratio (e.g., 16:9) of the image provided by the fixed
focal length lens 2 may be different than the aspect ratio of the
image provided by the zoom lenses 3 or 4. In this case, as was shown
in FIG. 2B, the user control 42 (e.g., the zoom button 42c) may
input user commands for changing the aspect ratio of the image sensor
2 in order to obtain a variable panoramic effect that transitions
from the wide angle of the lens 2 toward a narrower angle approaching
the effect of the 4:3 aspect ratio of the zoom lens 3.
FIG. 9 depicts a flow diagram showing a method for capturing digital
images using the digital camera of FIG. 7. This figure is mostly
a composite of the blocks in FIGS. 3 and 6, and most of the blocks
retain the same reference characters for the same block functions
and steps. In lens setting block 100, when the camera 10B is turned
on using a power switch (not shown), the first and second zoom lenses
3 and 4 are set to default positions, which are preferably the wide
angle position of each lens (e.g., the 38 mm position for lens 3
and the 125 mm position for lens 4).
In panoramic decision block 102, if the user presses the panoramic
button 42b (i.e., a yes response to block 102), the control processor
and timing generator 40 controls the analog multiplexer 34 to use
(third sensor block 115) the output of the analog signal processor
(ASP1) 26, so that the output of the third image sensor 12 is provided
to the A/D converter 36. Thereupon, a preview image from the image
sensor 12 is captured and displayed in preview block 116. If the
zoom button is pressed at this point (having specified that the
wide angle image is being used), the aspect ratio of the image is
modified in the aspect ratio adjustment block 118 so as to obtain
a variable panoramic effect from the wide angle of the lens 2. Then,
if the shutter button is pressed, a still image is captured in capture
block 120 using the output of the third sensor 12.
If the panoramic decision block 102 is not engaged (i.e., the user
has not pressed the panoramic button 42b), control is transferred
to the zoom position block 122. In zoom position block 122, if the
user presses the zoom button 42c and obtains a position beyond X
(i.e., something greater than 125 mm and therefore a yes response
to block 122), the control processor and timing generator 40 controls
the analog multiplexer 34 to use (second sensor block 134) the output
of the analog signal processor (ASP1) 24, so that the output of
the second image sensor 16 is provided to the A/D converter 36.
Thereupon, a preview image from the image sensor 16 is captured
and displayed in preview block 136. Then, if the shutter button
is pressed, a still image is captured in capture block 140 using
the output of the second sensor 16. If the zoom button is pressed
at this point in the zoom button block 138, control is returned
to the zoom position block 122.
In zoom position block 122, if the user presses the zoom button
42c and obtains a position less than a position X (i.e., something
less than 125 mm and therefore a no response to block 122), the
control processor and timing generator 40 controls the analog multiplexer
34 to use (first sensor block 124) the output of the analog signal
processor (ASP2) 27, so that the output of the first image sensor
14 is provided to the A/D converter 36. Thereupon, a preview image
from the image sensor 14 is captured and displayed in preview block
126. Then, if the shutter button 42a is pressed, a still image is
captured in capture block 130 using the output of the first sensor
16. If the zoom button is pressed at this point in the zoom button
block 128, control is returned to the zoom position block 122, and
the process is repeated.
FIG. 19 represents additional embodiments, where a digital camera
10D includes two (the fourth embodiment) fixed focal length lenses
or a digital camera 10E includes three (the fifth embodiment) fixed
focal length lenses, each providing an image to a corresponding
imaging array. FIG. 19 specifically depicts a block diagram of a
digital camera 10E according to the fifth embodiment. In the fifth
embodiment, a digital camera 10E includes three fixed focal length
lens, each providing an image to a corresponding image sensor. The
first fixed focal length lens 2a provides an image to the first
image sensor 12a. The second fixed focal length lens 2b provides
an image to the second image sensor 12b. The third fixed focal length
lens 2c provides an image to the third image sensor 12c. A user
zoom control on the camera selects, depending on its setting, either
the output of the first image sensor 12a, the output of the second
image sensor 12b, or the output of the third image sensor 12c. More
specifically, the user zoom control on the camera selects either
the output of one of the three image sensors to provide a rough
magnification setting, and in addition uses a digital zoom provided
by the image processor 50 to provide fine magnification control.
For example, the first focal length lens 2a may have a focal length
of 30 mm equiv. (35 mm equivalent), the second fixed focal length
2b lens may have a focal length of 90 mm equiv., and the third fixed
focal length lens 2c may have a focal length of 135 mm equiv. The
zoom lens control may provide settings from 30 mm to 270 mm. When
the user selects 60 mm, for example, the output from the first sensor
12a is selected, along with a 2.times. digital zoom. When the user
selects 270 mm, the output of the third sensor 12c is selected,
along with 2.times. digital zoom.
In the fourth embodiment, a digital camera 10D includes two fixed
focal length lens, each providing an image to a corresponding image
sensor. Consequently, for the fourth embodiment, FIG. 19 is modified
such that the third fixed focal length lens 2c, and its ancillary
components and circuitry, is eliminated. A user zoom control on
the camera selects, depending on its setting, either the output
of the first image sensor 12a, or the output of the second image
sensor 12b. For example, the first focal length lens 2a may have
a focal length of 30 mm equiv. (35 mm equivalent), and the second
fixed focal length 2b lens may have a focal length of 90 mm equiv.
The zoom lens control 42c may provide settings from 30 mm to 270
mm. When the user selects 60 mm, for example, the output from the
first sensor 12a is selected, along with a 2.times. digital zoom.
When the user selects 270 mm, the output of the second sensor 12b
is selected, along with 3.times. digital zoom. The remaining aspects
of the digital cameras 10D and 10E are similar to the digital camera
10B shown in FIG. 4, and retain the same reference characters. Reference
is therefore made to FIG. 4 for further description of these aspects
of the digital cameras 10D and 10E.
The perspective views of digital cameras 10D and 10E are not shown,
as they are substantially similar to the perspective views of FIGS.
5A and 5B, except that another optical relay subassembly is included
for the digital camera 10E.
FIG. 20 depicts a flow diagram showing a method for capturing digital
images using the digital camera 10E of FIG. 20. In a power up block
300, the camera 10E is turned on using a power switch (not shown).
In zoom position block 302, if the user presses the zoom button
42c and obtains a position beyond X (e.g., something equal to or
greater than 90 mm equiv. and therefore a yes response to block
302), control is transferred to the second zoom position block 314.
There, if the zoom button 42c is indicating a position beyond Y
(e.g., something equal to or greater than 135 mm equiv. and therefore
a yes response to block 314), the control processor and timing generator
40 controls the analog multiplexer 34 to use (third sensor block
318) the output of the analog signal processor (ASP3) 26, so that
the output of the third image sensor 12c is provided to the A/D
converter 36. If the zoom control 42c is requesting a focal length
other than the optical 135 mm equiv., digital zoom is applied to
the image in the zoom block 306 to bring the image up to the requested
focal length. Thereupon, a preview image from the image sensor 12c
is captured and displayed in preview block 308. Then, if the shutter
button is pressed, a still image is captured in capture block 312
using the output of the third sensor 12c. If the zoom button is
pressed at this point in the zoom button block 310, control is instead
returned to the zoom position block 302.
If the zoom button 42c is indicating a position less than Y (i.e.,
something less than 135 mm equiv. and therefore a no response to
block 314), the control processor and timing generator 40 controls
the analog multiplexer 34 to use (second sensor block 316) the output
of the analog signal processor (ASP2) 24, so that the output of
the second image sensor 12b is provided to the A/D converter 36.
If the zoom control 42c is requesting a focal length other than
the optical 90 mm equiv., digital zoom is applied to the image in
the zoom block 306 to bring the image up to the requested focal
length. Thereupon, a preview image from the image sensor 12b is
captured and displayed in preview block 308. Then, if the shutter
button is pressed, a still image is captured in capture block 312
using the output of the second sensor 12b. If the zoom button is
pressed at this point in the zoom button block 310, control is instead
returned to the zoom position block 302.
In zoom position block 302, if the user presses the zoom button
42c and obtains a position less than a position X (i.e., something
less than 90 mm and therefore a no response to block 302), the control
processor and timing generator 40 controls the analog multiplexer
34 to use (first sensor block 304) the output of the analog signal
processor (ASP1) 22, so that the output of the first image sensor
12a is provided to the A/D converter 36. If the zoom control 42c
is requesting a focal length other than the optical 30 mm equiv.,
digital zoom is applied to the image in the zoom block 306 to bring
the image up to the requested focal length. Thereupon, a preview
image from the image sensor 12a is captured and displayed in preview
block 308. Then, if the shutter button 42a is pressed, a still image
is captured in capture block 312 using the output of the first sensor
12a. If the zoom button is pressed at this point in the zoom button
block 310, control is returned to the zoom position block 302, and
the process is repeated.
A number of advantages may be obtained by use of the fixed focal
length lenses in the fourth and fifth embodiments. The aperture
of each lens can be kept quite large (e.g., f/2.8 at least for the
widest angle lens), thereby providing a high speed, low light lens.
In addition, the image quality can be kept higher than for a comparable
zoom lens. When digital zooming is employed, there are no moving
parts for the zoom--even though there are two (or three) optical
settings--and the zoom is completely silent and relatively fast
in zoom focal length transitions.
In the sixth embodiment (which is not shown as a separate block
diagram), a digital camera 10F includes four fixed focal length
lenses, each providing an image to a corresponding image sensor.
Consequently, for the sixth embodiment, FIG. 19 is modified such
that a fourth fixed focal length lens 2d, and its ancillary components
and circuitry, is added. A user zoom control on the camera selects,
depending on its setting, either the output of the first image sensor
12a, the output of the second image sensor 12b, the output of the
third sensor 12c, or the output of the fourth sensor 12d. For example,
the first focal length lens 2a may have a focal length of 30 mm
equiv. (35 mm equivalent), and the second fixed focal length 2b
lens may have a focal length of 60 mm equiv., the third fixed focal
length 2b lens may have a focal length of 120 mm equiv., and the
fourth fixed focal length 2b lens may have a focal length of 270
mm equiv. The zoom lens control 42c may provide settings from 30
mm to 400 mm. When the user selects 45 mm, for example, the output
from the first sensor 12a is selected, along with a 1.5.times. digital
zoom. When the user selects 90 mm, for example, the output from
the second sensor 12b is selected, along with a 1.5.times. digital
zoom. When the user selects 240 mm, for example, the output from
the third sensor 12c is selected, along with a 2.times. digital
zoom. When the user selects 400 mm, the output of the fourth sensor
12d is selected, along with 1.5.times. digital zoom. The remaining
aspects of the digital camera 10F are similar to the digital camera
10E shown in FIG. 19, and reference is therefore made to FIG. 19
for further description of these aspects of the digital camera.
The perspective views and flow diagram of the digital camera 10F
are not shown, as they are substantially similar to the perspective
views of FIGS. 5A and 5B and the flow diagram of FIG. 20, except
that yet another optical relay subassembly, and another flow column
in FIG. 20 for the fourth sensor 12c, is included for the digital
camera 10F.
In many of the foregoing embodiments, digital zooming is used.
Digital zooming is a well-known process and any of a variety of
techniques may be used. One such digital zooming capability is described
in commonly-assigned pending U.S. Patent Application Publication
No. 2003/0202113, "Electronic Still Camera and Image Processing
Method" filed on Aug. 1, 2002 in the name of Sumito Yoshikawa
and which is incorporated herein by reference. For the type of system
disclosed in this pending patent application, as well as for the
system according to the present invention, the image sensor includes
an array of discrete light sensitive picture elements overlaid with
a color filter array (CFA) pattern to produce color image data corresponding
to the CFA pattern. The output data from the image sensor is applied
to an analog signal processing (ASP) and analog/digital (A/D) conversion
section, which produces digital CFA data from the color image data.
The resultant digital data is applied to a digital signal processor,
such as the image processor 50 (referring to FIG. 1 of the present
disclosure), which interpolates red, green, and blue (RGB) color
image data for all of the pixels of the color image sensor. The
CFA image data represents an image of a fixed size, such as 2048
columns of pixels.times.1536 rows of pixels. A digitally zoomed
image is provided by taking the center section of the CFA image
data and interpolating additional pixels that fall in between the
pixels provided by the image sensor. For example, a 2:1 digital
zoom is provided by using only the center 1024 columns.times.768
rows of the CFA image data, and by interpolating one additional
row and column in between each of the rows and columns of the center
CFA image data, so as to enlarge the center of the image. The output
of the image processor 50 is a color interpolated and digitally
zoomed image, with 2048 columns and 1536 rows of RGB data, provided
from the center 1024 columns.times.768 rows of CFA image data.
In operation of the present imaging system according to the aforementioned
Yoshikawa patent disclosure, the user operates the digital camera,
e.g., the digital camera 10E (FIG. 19), to take pictures while observing
the image on the color LCD image display 70. The digital CFA image
for each of the captured images is processed by the image processor
50 and displayed in a "thumbnail" or subsampled format
in the preview step (e.g., steps 308 in FIG. 20). If the observed
zoom amount is not desired, the user then changes the zooming/cropping
setting in a zoom selection/cropping step (e.g., steps 302, 314
in FIG. 20) by using the zoom button 42c. The amount of digital
zooming is determined by the control processor and timing generator
40 and provided to the image processor 50. The control processor
and timing generator 40 selects which of the image sensor outputs
to use (by controlling the analog mux 34), and the amount of digital
zoom needed, which in combination provide the desired overall zoom
setting. For example, a 2.5:1 overall zoom setting can be provided
by selecting (using the analog mux 34) a lens and image sensor that
provides a 2:1 optical zoom and also instructing the image processor
50 to provide a 5:4 digital zoom setting, which uses the center
1638 columns.times.1230 rows (from the 2048 columns.times.1536 rows
of CFA image data).
In an additional embodiment of the invention shown in FIG. 21,
the two (or three) lenses have identical focal lengths, and the
imaging arrays are different sizes (e.g. both sensors are, e.g.,
3.1 effective megapixel sensors with 2048 columns.times.1536 rows
of pixels, but the first image sensor 412a has 3.1 micron square
pixels and the second image sensor 412b has 6.2 micron square pixels,
so that the diagonal of the second image sensor is twice as large
as the first image sensor). With the differently sized imaging arrays,
each lens is designed to fill the area of the imaging array and
each lens-array combination can have substantially the same actual
focal length, i.e., the same lens to array distance. However, the
35 mm equiv. of each lens will be different, in proportion to the
difference in the diagonal size of the array; consequently, each
lens will have a different field of view. In FIG. 21, in this additional
embodiment, a digital camera 10G includes a first fixed focal length
lens 402a that provides an image to a first image sensor 412a, which
has 3.1 micron pixels. A second fixed focal length lens 402b provides
an image to a second image sensor 412b, which has 6.2 micron pixels.
A user zoom control 42 on the camera selects, depending on its setting,
either the output of the first image sensor 412a or the output of
the second image sensor 412b. More specifically, the user zoom control
on the camera selects the output of one of the two image sensors
to provide a rough magnification setting based on the 35 mm equiv.
focal length of the lenses 402a and 402b, and in addition uses a
digital zoom provided by the image processor 50 to provide fine
magnification control. For example, the first focal length lens
402a may have an actual focal length of 16 mm, which provides a
35 mm equiv. focal length of about 80 mm because the pixels are
3.1 mm so that the diagonal size is about 8 mm. The second fixed
focal length 402b lens may also have an actual focal length of 16
mm, but it provides a 35 mm equivalent focal length of about 40
mm, because the pixels are 6.2 mm so that the diagonal size is about
16 mm. The zoom lens control may provide settings from 40 mm to
160 mm. When the user selects 60 mm, for example, the output from
the second sensor 412b is selected, along with a 1.5.times. digital
zoom. When the user selects 160 mm, for example, the output of the
first sensor 412a is selected, along with 2.times. digital zoom.
The remaining aspects of the digital cameras 10G are similar to
the digital camera 10B shown in FIG. 4, and retain the same reference
characters. Reference is therefore made to FIG. 4 for further description
of these aspects of the digital camera 10G.
A further advantage of the invention is that use of dual zooms
provides an extended optical zoom range in a digital camera where
the movement between user-requested zoom positions may be undertaken
in an expedited manner. Since motorized zooming is typically done
between discrete zoom steps rather than continuously, the full range
of a zoom system is divided into a finite number of discrete steps.
For example, as shown in FIG. 22, a two zoom system in accordance
with the invention may be divided into a first zoom range 500 providing
a 38 mm 114 mm equiv. zoom lens range and a second zoom range 502
providing a 133 mm 380 mm equiv. zoom lens range Such an arrangement
may be provided by the digital camera 10B shown in FIG. 4. According
to this arrangement, the zoom and focus motors 5a and 5b drive the
respective zoom lenses 3 and 4 through a finite series of discrete
steps, where each step represents, for the example shown in FIG.
22, 0.5.times. zoom steps over the lower zoom range, and 1.times.
zoom steps over the higher zoom range More particularly, the zoom
and focus motor 5a drives the zoom lens 3 from 38 mm to 114 mm in
five discrete steps, with the steps corresponding to 1.times. (38
mm), 1.5.times. (57 mm), 2.times. (76 mm), 2.5.times. (95 mm) and
3.times. (114 mm) zoom steps. The zoom and focus motor 5b drives
the zoom lens 4 from 133 mm to 380 mm in seven discrete steps, with
the steps corresponding to 3.5.times. (133 mm), 4.times. (152 mm),
5.times. (190 mm), 6.times. (228 mm), 7.times. (266 mm), 8.times.
(304 mm), 9.times. (342 mm), and 10.times. (380 mm) zoom steps.
The two lenses are separated in focal length by a one step gap 503
(i.e., by 19 mm, corresponding to the 0.5.times. gap between the
3.times. zoom focal length and the 3.5.times. zoom focal length.).
In operation, the user operates the user control 42 in order to
select a zoom setting, whereby the zoom and focus motors 5a and
5b are responsive to the user control 42 for adjusting the zoom
lenses through the first plurality of discrete zoom positions 500
for the first zoom lens 3 and through the second plurality 502 of
discrete zoom positions for the second zoom lens 4. The control
processor and timing generator 40, acting as a zoom controller,
controls the zoom and focus motors 5a and 5b and enables an express
mode when a user initiated change in the user control specifies
a zoom transition from a present zoom setting within one of the
plurality of discrete zoom positions in one of the ranges to a target
zoom setting within the other plurality of discrete zoom positions
in the other range. The control processor and timing generator 40
causes the zoom and focus motor of the lens containing the target
position to immediately move the corresponding zoom lens to the
target zoom position without powering the other zoom and position
motor through any intervening discrete zoom positions, thereby enabling
an express zooming sequence in which the zoom and focus motors of
the lens not containing the target position do not have to traverse
all of the intervening zoom positions between the present zoom setting
and the target zoom setting.
An example is shown in FIG. 22. In the power up mode, both zoom
lenses will be brought to their minimum focal length positions,
i.e., the zoom lens 3 will be driven to the 38 mm position and the
zoom lens 4 will be driven to the 133 mm position. If the user initially
chooses to view a subject at the widest angle position, say 38 mm
equiv., the zoom lens 3 will provide its widest angle image to the
image sensor 14 (FIG. 4) and the analog multiplexer 34 will select
the first image output 14e from the first image sensor 14. If the
user then presses the zoom button 42c to a tele position, say 228
mm equiv., the usual response in a single zoom lens that spanned
the range from 38 mm to 228 mm would be to drive the zoom lens through
an 8 step sequence 504 as shown in FIG. 22. However, in the express
mode according to the invention, the control processor and timing
generator 40 immediately directs the zoom and focus motor 5b to
drive the lens 4 through a 3 step sequence 506 from 133 mm to 228
mm. Meanwhile, the zoom lens 3 remains at its widest setting. Consequently,
five steps of movement are saved and the movement between user-requested
zoom positions is undertaken in an expedited manner compared to
the prior art situations. Clearly, FIG. 22 is only an example, and
many other variations of step length and zoom ranges are within
the scope of the invention. For example, in power up mode, the lens
4 could be set to the maximum focal length (380 mm) rather than
the widest focal length (133 mm). Then the camera could be immediately
switched from the wide-angle position (38 mm equiv.) to the maximum
telephoto position (380 mm equiv.) immediately, simply by switching
the analog mux 34 to provide the output of the 2.sup.nd image sensor
16.
The concept of multiple lenses and multiple sensors, and the use
of an integrated image capture assembly, may be adapted for use
in a cell phone of the type having a picture taking capability.
Accordingly, and as shown in FIG. 23A, a cell phone 600 includes
a phone stage comprising a microphone 602 for capturing the voice
of a caller, related electronics (not shown) for processing the
voice signals of the caller and the person called, and a speaker
604 for reproducing the voice of the one called. A keypad 606 is
provided for entering phone numbers and image capture commands,
and a (LCD) display 608 for showing phone-related data and for reproducing
images captured by the phone or received over the cellular network.
The rear view of the cell phone 600 shown in FIG. 23B identifies
some of the internal components, including a cellular image capture
assembly 610 connected via the image processor 50 (as shown in FIG.
1) to a cellular processing stage comprising the cellular processor
90 and the modem 92. The cellular processor 90 receives and processes
the image data from the image processor 50 and the voice data captured
by the microphone 602, and transfers the image and voice data to
the cellular modem 92. The cellular modem 92 converts the digital
image and voice data into the appropriate format for transmission
by the antenna 94 to a cellular network.
As the cellular image capture assembly 610 is shown in FIGS. 24A
and 24B, where FIG. 24B is a top view of the assembly 610 taken
along the lines 24B--24B in FIG. 24A, the assembly 610 comprises
an integrated packaging of the optical and imaging components on
a common substrate 620. More specifically, the assembly 610 includes
a first fixed focal length lens 612 and a first image sensor 614,
and a second fixed focal length lens 616 and a second image sensor
618. The first lens 612, preferably a fixed focal length wide angle
lens (such as a 40 mm equiv. lens), forms an image on the first
image sensor 614, and the second lens 616, preferably a fixed focal
length telephoto lens (such as 100 mm equiv. lens), forms an image
on the second image sensor 618. Both of the lenses are oriented
in the same direction in order to form images of the same portion
of the overall scene in front of them, albeit with different fields
of view.
Each lens 612 and 616 and each associated image sensor 614 and
618 are mounted to the substrate 620 with an IR cut filter in between
to reduce the incidence of IR radiation on the image pixels. Electronic
components 624, such as resistors, capacitors and power management
components, are also mounted on the substrate 620. The image signals
are taken from the substrate 620 via a flex connector 626. The data
taken from the assembly 610 may be raw image data, or if suitable
processors (not shown) are on board the substrate 620, the data
could be YUV image data or JPEG image data. Moreover, the image
processor 50 may provide digital zooming between the wide angle
and the telephoto focal lengths; the user may initiate such zooming
via a user interface displayed on the (LCD) display 608 and by keying
appropriate buttons on the keypad 606. Furthermore, the wide angle
image sensor 614 may have high resolution, e.g., higher than that
of the telephoto image sensor 618, in order to provide a higher
quality source image for the digital zooming.
In one embodiment, the wide angle lens 612 is set to its hyperfocal
distance, which means it is in focus from a few feet to infinity
without need for any focus adjustment by the user. The telephoto
lens 616 is automatically focused by an auto focus subsystem 628.
This is required because the hyperfocal distance increases as the
focal length increases, and so the focus needs to be adjusted in
order to obtain proper focus for objects at typical (e.g. 4' to
12') distances. By using only one focusing subsystem 628 for the
telephoto lens 616, the cost and size can be reduced.
An important constraint in this embodiment is the "z"
dimension 630, which must be held to a very small figure consistent
with a cell phone layout and architecture. This may be obtained
by careful choice of the telephoto focal length and the size of
the sensor. For example, the size of the sensor 616, and consequently
the size of the image that must be produced to fill the sensor,
may be made small enough to reduce the focal length to an acceptable
z dimension 630.
In a further embodiment, as discussed in connection with FIG. 21,
the two lenses may have approximately identical focal lengths, with
the imaging arrays being of different sizes. With the differently
sized imaging arrays, each lens is designed to fill the area of
the imaging array and each lens-array combination will have substantially
the same actual focal length, i.e., the same lens to array distance.
However, the 35 mm equiv. of each lens will be different; consequently,
each lens will have a different field of view.
While not shown in detail in FIGS. 24A and 24B, but similarly as
was explained in connection with FIG. 1, an analog output signal
from the first image sensor 614 is amplified by a first analog signal
processor and provided to a first input of a control element, e.g.,
an analog multiplexer control element provided as one of the electronic
components 624 on the substrate 620. The analog output signal from
the second image sensor 618 is amplified by a second analog signal
processor and provided to a second input of the control element.
The function of the control element is to select either the first
sensor output from the first image sensor 614 or the second sensor
output from the second image sensor 618, depending on user input
from the keypad 606 as to zoom selection, thereby providing a selected
sensor output from the cellular image capture assembly 600 to the
image processor 50.
The invention has been described in detail with particular reference
to certain preferred embodiments thereof, but it will be understood
that variations and modifications can be effected within the spirit
and scope of the invention.
PARTS LIST
1 image capture assembly 1a optical relay subassembly 1b optical
relay subassembly 1c optical relay subassembly 1a(1) first optical
relay subassembly 1a(2) second optical relay subassembly 1a(3) third
optical relay subassembly 1a(4) fourth optical relay subassembly
1d front optical profile of the camera 2 fixed focal length lens
2a first fixed focal length lens 2b second fixed focal length lens
2c third fixed focal length lens 2d fourth fixed focal length lens
2e first image sensor output 3 first zoom lens 4 (second) zoom lens
5a zoom and focus motors 5b zoom and focus motors 5c connecting
gear train 6a lens barrel 6b fixture 7a relay lens components 7b
movable relay (zoom) lens components 8a mirror prism 8b mirror prism
9a aperture shutter assembly 9b aperture shutter assembly 10A digital
camera (first embodiment) 10B digital camera (second embodiment)
10C digital camera (third embodiment) 10D digital camera (fourth
embodiment) 10E digital camera (fifth embodiment) 10F digital camera
(sixth embodiment) 10G digital camera (seventh embodiment) 12 first
image sensor 12a first image sensor 12b second image sensor 12c
third image sensor 12d fourth image sensor 12e first image output
13 clock drivers 14 second image sensor 14e second image output
15 clock drivers 16 third image sensor 16e third image output 17
clock drivers 18 16:9 aspect ratio panoramic image 18a horizontal
margin 18b vertical margin 19 4:3 aspect ratio image 22 first analog
signal processor (ASP1) 24 second analog signal processor (ASP2)
26 third analog signal processor (ASP3) 34 control element (analog
multiplexer) 36 analog-to-digital converter 38 DRAM buffer memory
40 control processor and timing generator 42 user controls 42a shutter
button 42b panoramic button 42c zoom button 42d multi-position selector
46 automatic focus and automatic exposure detectors 48 electronic
flash 50 image processor 52 memory card interface 54 removable memory
card 56 RAM memory 58 firmware memory 62 host interface 64 interconnection
66 host PC 70 color LCD image display 90 cellular processor 92 cellular
modem 94 antenna 100 lens setting block 102 panoramic decision block
104 second sensor block 106 preview block 108 zoom adjustment block
110 capture block 112 power down block 114 first sensor block 115
third sensor block 116 preview block 118 aspect ratio adjustment
block 120 capture block 122 zoom position block 124 first sensor
block 126 preview block 128 zoom button block 130 capture block
134 second sensor block 136 preview block 138 zoom button block
140 capture block 201 width-wise dimension 204 battery 210 front
to rear dimension 300 power up block 302 zoom position X block 304
first sensor block 306 digital zoom block 308 preview block 310
zoom button block 312 capture block 314 zoom position Y block 316
second sensor block 318 third sensor block 320 removed section 322
yes response 402a first lens 402b second lens 412a first (smaller)
sensor 412b second (larger) sensor 500 first zoom range 502 second
zoom range 503 one step gap 504 17 step zoom sequence 506 9 step
zoom sequence 600 cell phone 602 microphone 604 speaker 606 keypad
608 (LCD) display 610 cellular image capture assembly 612 first
fixed focal length lens 614 first image sensor 616 second fixed
focal length lens 618 second image sensor 620 substrate 622 IR cut
filter 624 electronic components 626 flex connector 628 auto focus
subsystem 630 z dimension
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