Digital Camera Patent Abstract
A display unit of a digital camera includes a liquid crystal display
(LCD) panel that displays a photographed image by the digital camera
on an image display area of the LCD panel, and displays symbolic
information on an information area. A main back-light unit is provided
to illuminate the image display area of the LCD panel, and a sub-back-light
unit is provided to illuminate the information display area of the
LCD panel, both of which can be independently driven. Digital Camera Patent Claims
What is claimed is:
1. A display unit of a digital camera comprising: a liquid crystal
display (LCD) panel that displays a photographed image by said digital
camera on an image display area of said LCD panel and displays a
symbolic information on an information display area; a main back-light
unit that illuminates said image display area of said LCD panel;
a sub-back-light unit that illuminates said information display
area of said LCD panel; and a driving circuit that independently
drives said main back-light unit and said sub-back-light unit.
2. The display unit of the digital camera of claim 1, wherein said
information display area is separated from said image display area.
3. The display unit of the digital camera of claim 2, further comprising:
a diffusion unit that extends along a total width of and parallel
to said LCD panel to diffuse light from said main back-light unit;
and a half-mirror disposed between said LCD panel and said diffusion
unit such that light from said sub-back-light unit is reflected
by said half-mirror toward said information area and that a light
from said main back-light unit passes through said half-mirror toward
said information display area.
4. The display unit of the digital camera of claim 1, wherein said
image display area is a total area of said LCD panel, and said information
display area is disposed within said image display area.
5. The display unit of the digital camera of claim 4, further comprising
a diffusion unit that includes: a main diffusion portion extending
along a total width of and parallel to said LCD panel, which diffuses
light from said main back-light unit; and a sub-diffusion portion
which angularly projects from an end of said main diffusion portion
to face said information display area to diffuse light from said
sub-back-light unit.
6. The display unit of the digital camera of claim 5, wherein said
light of said main back-light unit and said sub-back-light unit
have different wavelength range, and said display unit further comprises
color filter that selectively transmit said light of said main back-light
unit.
7. The display unit of the digital camera of claim 1, wherein said
main back-light unit comprises: a light source; a reflector that
reflects light from said light source to said image display area;
and a light transmitter that transmits said light from said light
source to said image display area.
8. The display unit of the digital camera of claim 7, wherein said
light source is a fluorescent tube.
9. The display unit of the digital camera of claim 7, wherein said
reflector is a container-like concave mirror.
10. The display unit of the digital camera of claim 9, wherein
said concave mirror comprises: a semicircular cylindrical concave
mirror disposed parallel to said light source, that reflects said
light from said light source substantially parallel to said LCD
panel; and an inclined flat mirror that is uniformly connected to
said semicircular cylindrical concave mirror and is inclined such
that said light reflected by said semicircular cylindrical concave
mirror is reflected by said inclined flat mirror toward said image
display area.
11. The display unit of the digital camera of claim 1, wherein
said main back-light unit comprises: a flat fluorescent lamp as
a light source; and a reflector that reflects light from said light
source to said image display area.
12. The display unit of the digital camera of claim 1, wherein
said sub-back-light unit comprises a plurality of light emitting
diodes (LEDs) as a light source.
13. The display unit of the digital camera of claim 1, further
comprising a diffusion unit that diffuses light from said main back-light
unit and said sub-back-light unit.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display unit of a digital camera,
including a liquid crystal display (LCD) for displaying a photographed
image.
2. Description of the Related Art
A digital camera is known that includes a LCD unit for displaying
a photographed image and related information, such as a date, an
operation mode and so forth. Usually, the LCD is illuminated by
a back-light such that the displayed image is sufficiently illuminated
even outdoors. The back-light has a high electric power consumption
and exerts a negative influence upon a battery's duration of the
digital camera. Symbolic information, such as a date, an operation
mode and so forth, is generally displayed in an image display area
of the LCD, and as such it is necessary to illuminate the LCD unit
with the back-light even when only the information is displayed.
Occasionally, an additional display for displaying only the information
is utilized. However, the digital camera including such an additional
display is complex and a total number of components is increased.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a display
unit of a digital camera capable of displaying both a photographed
image and information with minimal electric power consumption.
A display unit of a digital camera according to the present invention
comprises a liquid crystal display (LCD) panel, a main back-light
unit, a sub-back-light unit, and a driving circuit. The LCD panel
displays a photographed image by the digital camera on an image
display area of the LCD panel and displays a symbolic information
on an information display area. The main back-light unit illuminates
the image display area of the LCD panel. The sub-back-light unit
illuminates the information display area of the LCD panel. The driving
circuit independently drives the main back-light unit and the sub-back-light
unit.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be better understood from the description
of the preferred embodiments of the invention set forth below together
with the accompanying drawings, in which:
FIG. 1 is a perspective view showing a digital camera that includes
a first embodiment of a display unit according to the present invention;
FIG. 2 is a view showing an image exhibited by the display unit
of the first embodiment;
FIG. 3 is a sectional side view showing the display unit of the
first embodiment;
FIG. 4 is a block diagram of the digital camera in FIG. 1;
FIG. 5 is a sectional side view showing a display unit of a second
embodiment;
FIG. 6 is a sectional side view showing a display unit of a third
embodiment;
FIG. 7 is a sectional side view showing a display unit of a fourth
embodiment; and
FIG. 8 is a graph showing a spectrum characteristic of a wavelength/luminance
relationship of light generated by a back-light unit, and a transmission
factor of color filters used in the fourth embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, the preferred embodiments of the present invention
are described with reference to the attached drawings.
FIG. 1 is a perspective view showing a first embodiment of a digital
camera according to the present invention. The digital camera 10
includes a camera body 11 of a rectangular parallelepiped shape.
A display unit 20, pivotable at a hinge 11d on an upper surface
11a of the body 11, is swingable between an angle where the display
unit 20 is disposed in a recess 11e on the upper surface 11a and
an angle X where the display unit 20 projects from the upper surface
11a. The display unit 20 includes a liquid crystal display (LCD)
panel 21 for displaying an image and symbolic information (FIG.
2). An optical system 19, having a lens 18, is disposed on a front
surface 11b of the body 11 for photographing an image in a visual
field thereof. A release button 51, a back-light selection button
52 and a mode selection button 53 are disposed on the upper surface
11a of the body 11, and a power switch 59 is disposed on a back
surface 11c of the body 11.
FIG. 2 is a view showing an image exhibited by the LCD panel 21
of the display unit 20. The photographed image is displayed in a
image display area E1 from a top A of the LCD panel 21 to a lower
portion B adjacent to a bottom C of the LCD panel 21. The symbolic
information, such as a date, an operation mode and so forth, are
displayed on an information display area E2 between the portion
B (a bottom) of the area E1 and the bottom C of the LCD panel 21.
Therefore, the information display area E2 is separated from the
image display area E1.
As shown in FIG. 3, the LCD panel 21 is illuminated by a main,
edge-light type back-light unit 22 and a sub-back-light unit 23
from a back side of the LCD panel 21. The main back-light unit 22
includes a fluorescent lamp light source 22b, a light transmitter
22a, and a reflector 22e. The light source 22b is a fluorescent
tube, and the light transmitter 22a transmits light from the light
source 22b toward image display area E1 of the LCD panel 21. The
reflector 22e is a container-like concave mirror, which includes
a semicircular cylindrical concave mirror 22c extending along a
longitudinal axis of the light source 22b, and an inclined flat
mirror 22d unitedly and uniformly connected to the semicircular
cylindrical concave mirror 22c. Light from the light source 22b
is reflected by the semicircular cylindrical concave mirror 22c
substantially parallel to the LCD panel 21. The inclined flat mirror
22d extends along the LCD panel 21 and approaches the LCD panel
21 in a direction departing from the semicircular cylindrical concave
mirror 22c. The light reflected by the semicircular cylindrical
concave mirror 22c is then reflected by the inclined flat mirror
22d, and transmitted by the light transmitter 22a toward the image
display area E1 of the LCD panel 21. A diffusion unit 24 is disposed
along a total width of and parallel to a rear surface of the LCD
panel 21, diffusing the light radiating from the main back-light
unit 22.
The sub-back-light unit 23 includes a plurality of light emitting
diodes (LEDs) 23a linearly aligned behind the information display
area E2. One LED consumes less than 10% of an electric power consumed
by the main back-light unit 22. Thus, the sub-back-light unit 23,
consisting of two or three LEDs has significantly a lower electric
power consumption in comparison with that of the main back-light
unit 22. While the power in the digital camera 10 is turned on,
the information display area E2 is illuminated by the sub-back-light
unit 23.
The main back-light unit 22 and the sub-back-light unit 23 are
independently driven. When the photographed image is displayed on
the LCD panel 21, both the main back-light unit 22 and the sub-back-light
unit 23 are driven, thus the image is illuminated together with
the symbolic information. When only the symbolic information is
to be displayed, only the sub-back-light unit 23 is driven and the
main back-light unit 22 is not driven, thus electric power consumption
is minimized.
FIG. 4 is a block diagram of the digital camera 10. The optical
system 19 focuses an optical image in the visual field on an image
sensor (area sensor) 30. The optical image is converted into an
analog electrical signal by the image sensor 30, amplified by an
amplifier 31, and then converted by an A/D converter 32 into a digital
image-pixel signal. The image sensor 30 is controlled by a sensor
driving circuit 33. The sensor driving circuit 33 is controlled
by a CPU 40.
An output of the digital image-pixel signal from the A/D converter
32 is input to a digital signal processor (DSP) 41 such that the
output signal undergoes various image-signal processings, such as
shading correction, interpolation and noise reduction. The processed
digital image-pixel signal in the DSP 41 is once stored in an image
memory 43 according to a control of a memory controller 42. The
processed digital image-pixel signal stored in the image memory
43 is read by the memory controller 42, controlled by a CPU 40,
from the image memory 43, and encoded by an LCD signal processor
61 from R (red), G (green) and B (blue) digital signals to a video
signal format consisting of a color differential signals (Cr, Cb)
and a luminance signal (Y). Since images are continuously input
to the image sensor 30 and transferred to the image memory 43, the
image in the visual field is displayed by the LCD panel 21 as a
motion picture in real-time. The symbolic information, such as a
date, an operation mode and so forth, are generated by the CPU 40.
The date information is read from a clock circuit (not shown) in
the CPU40, and the operation mode information is supplied from the
mode selection switch 53 to the CPU 40. The CPU 40 reads character
and symbolic data from a ROM 49, in accordance with the date information
and the operation mode information. The CPU 40 transfers the character
and symbolic data to a LCD signal processor 61, such that the information
is displayed on the area E2.
The main back-light unit 22 and sub-back-light unit 23 are independently
driven by driving circuits 62 and 63, respectively.
When the release button 51 is depressed halfway, images are continuously
input to the image sensor 30 and transferred to the image memory
43a, such that the moving image is displayed in the area E1. When
the release button 51 is fully depressed, the still image is stored
in a memory 44, which stores photographed still images successively.
In the body 11, a battery 46 is disposed for supplying electric
power to the components of the digital camera 10, such as the main
back-light unit 22, sub-back-light unit 23 and sensor driving circuit
33. The electric power of the battery 46 is supplied, through a
DC/DC converter 45 for stabilizing the electric power, to the components.
The power switch 59 is connected to an output of the DC/DC converter
45 for switching the electric power.
An interface 80 is connected to the CPU 40, for outputting the
image from the memory 44 to a personal computer (not shown) or other
peripheral apparatus.
By pushing the mode selection switch 53, the operation mode of
the digital camera 10 is successively changed in an order of: "monitor"
mode, "photography" mode and "slide" mode.
In the "monitor" mode, an image focused on the image
sensor 30 is displayed by the display unit 20 in real-time, as a
moving image, and a photographing condition is selected and adjusted.
An angle of view, an exposure value and other conditions are manually
adjusted. In this mode, the main back-light unit 22 and the sub-back-light
unit 23 are driven, thus both the image display area E1 and the
information display area E2 are illuminated. However, the "monitor"
mode is not so frequently selected.
In the "photography" mode, first, the display of the
moving image is stopped and only the information is displayed. The
main back-light unit 22 is turned off and only the sub-back-light
unit 23 is turned on. When the release button 51 is depressed halfway,
the moving image is displayed again in the area E1. At this time,
both the main back-light unit 22 and the sub-back-light unit 23
are turned on. If the halfway depression is released, the display
of the moving image is stopped, and only the information is displayed.
At this time, the main back-light unit 22 is turned off and only
the sub-back-light unit 23 is turned on. When the release button
51 is fully depressed after the halfway depression of the release
button 51, a still image from the image sensor 30 is displayed in
the image display area E1, and stored in the memory 44. The photographer
can thus observe and confirm the image to be photographed. Then,
after the still image is stored in the memory 44, the display of
the still image in the area E1 is stopped, and only the information
is displayed by using the sub-back-light unit 23. In the "photography"
mode, the main back-light unit 22 is turned off unless the release
button 51 is depressed, thus enabling a lower power consumption.
In the "slide" mode, the photographed still image, stored
in the memory 44, is read out by the LCD signal processor 61, and
is displayed on the area E1. When a plurality of still images have
been already photographed, these images are successively displayed,
similarly to a slide projector. On starting the "slide"
mode, the main back-light unit 22 is turned off, and is driven again
when the still images are started to be displayed.
Since the main back-light unit 22 is driven only when the image
is displayed in the image display area E1, the electric power consumption
is minimized. An LCD panel only for information display is unnecessary,
so the digital camera 10 is simplified and a total number of components
is decreased in comparison with a conventional digital camera.
The main back-light unit 22 and the sub-back-light unit 23 can
be manually controlled by the back-light selection button 52, successively
and scrolling through commands in rotation. For example, in a first
selection, only the main back-light unit 22 is driven; in a second
selection, additionally, the sub-back-light unit 23 is driven; in
a third selection, the main back-light unit 22 is turned off; in
a fourth selection, the sub-back-light unit 23 is also turned off.
FIG. 5 is a sectional side view showing a display unit 120 of a
second embodiment. Like references indicate identical components
to those of the first embodiments. In this embodiment, a main back-light
unit 22' includes a flat fluorescent lamp 22b' as a light source
and a reflector 22d' for reflecting light of the flat fluorescent
lamp 22b'. While a sub-back-light unit 23 includes a plurality of
light emitting diodes 23a similar to those of the first embodiment.
A half mirror 26 is positioned behind the information display area
E2 between the diffusion unit 24 and the LCD panel 21, which transmits
the light from the main back-light unit 22', and reflects the light
from the sub-back-light unit 23 toward the information area E2.
When the image is displayed, both the image display area E1 and
the information display area E2 are illuminated by the main back-light
unit 22'. While the image is displayed, the sub-back-light unit
23 is turned off. When only the information is displayed, the main
back-light unit 22' is turned off and the sub-back-light unit 23
is driven. In addition to the effect of the first embodiment, the
electric power is further decreased when the image is displayed
together with the information, since the information is illuminated
by the main back-light unit 22'.
In a modification, the main back-light unit 22' may be constructed
from edge-light type back-light unit, similarly to the first embodiment.
FIG. 6 is a sectional side view showing a display unit 130 of a
third embodiment. Again, like references indicate identical components
to those of the first embodiment. Differently from the first embodiment,
an image display area E3 is disposed over the total area of the
LCD panel 21 and an information display area E2 is disposed within
the image display area E3, occasionally, the area E3 can be entirely
used as an image display area. A similar main back-light unit 22"
to that of the first embodiment is disposed, adjacent to the rear
surface of the LCD panel 21, and illuminates a total area of the
LCD panel 21 via an external inclined flat mirror 22d". The
sub-back-light unit 23 includes a plurality of light emitting diodes
23a, similarly to those of the first embodiment. A diffusion unit
25 includes a main diffusion portion 25a, which extends along a
total width of and parallel to the LCD panel 21, and a sub-diffusion
portion 25b, which angularly projects from an end of the main diffusion
portion 25a to face the information display area E2. The main diffusion
portion 25a diffuses light from the main back-light unit 22",
and the sub-diffusion portion 25b diffuses light from the sub-back-light
unit 23.
In a modification, the main-back-light unit 22" may be constructed
from a flat fluorescent lamp, similarly to the second embodiment.
When the image is displayed, both the image display area E3 and
the information display area E2 are illuminated by the main back-light
unit 22". While the image is displayed, the sub-back light
unit 23 is turned off. When only the information is displayed, the
main back-light unit 22" is turned off and the sub-back-light
unit 23 is driven. A similar effect to that of the second embodiment
is achieved in the third embodiment.
FIG. 7 is a sectional side view showing a display unit 140 of a
fourth embodiment. Again, like references indicate identical components
to those of the third embodiment. Similarly to the third embodiment,
an image display area E3 is disposed over the total area of the
LCD panel 21 and an information display area E2 is disposed within
the image display area E3. A diffusion unit 25 includes a main diffusion
portion 25a, which extends along a total width of and parallel to
the LCD panel 21, and a sub-diffusion portion 25b which angularly
projects from an end of the main diffusion portion 25a to face the
information display area E2. The other area E1, being independent
of the information display area E2, is a partial area for image
display. Similarly to the second embodiment, a main back-light unit
22' is disposed adjacent to the rear surface of the LCD panel 21,
which includes a flat fluorescent lamp 22b' as a light source and
a reflector 22d' for reflecting light from the flat fluorescent
lamp 22b'. Color filters 27 and 28 are disposed, corresponding to
the main back-light unit 22' and the sub-back-light unit 23, respectively.
Light of the main back-light unit 22' and the sub-back-light unit
23 are different in wavelength, and the color filters 27 and 28
have high transmission factors with respect to the light of the
main back-light unit 22' and the sub-back-light unit 23, respectively.
The color filter 27 is adhered to the rear surface of the LCD panel
21, at a position corresponding to the partial area E1, and the
color filter 28 is positioned between the sub-diffusion portion
25b and the sub-back-light unit 23. When both the partial area E1
and the information display area E2 are illuminated, the information
display area E2 has a higher luminosity than the partial area E1,
such that the symbolic information is clear even when there is an
image displayed over the area E3 which interferes with the information,
for example, due to a image using of similar color to that of the
information. As the filter 27 cuts off the light of the sub-back-light
unit 23, a border between the area E1 and the area E2 is emphasized.
The image display area E1 is not illuminated when only the information
display area E2 is to be illuminated, thus the information is clearly
displayed while minimizing power consumption. In this embodiment,
the total area E3 of the LCD panel 21 can be used as an image display
area.
When the image and the information are displayed, the area E1 is
illuminated by the main back-light unit 22', and the information
display area E2 is illuminated by the main back-light unit 22' and
the sub-back-light unit 23. When only the information is displayed,
the main back-light unit 22' is turned off.
In a modification, the main-back-light unit 22' may be incorporate
an edge-light, similarly to the first embodiment.
FIG. 8 is a graph showing a spectrum characteristic of a wavelength/luminance
relationship of light generated by the back-light(22, 22', 22"),
and a transmission factor of the color filters 27 and 28. The color
filter 27 has a high transmission factor L30 for light of shorter
wavelength, while the color filter 28 has a high transmission factor
L40 for light of longer wavelengths different than the wavelengths
transmitted by the color filter 27. A spectrum (luminance) of the
light of the main back-light unit 22' is shown by L20, and a spectrum
(luminance) of the light of the sub-back-light unit 23 is shown
by L10. The spectrums L10 and L20 have high values over different
wavelength ranges. When only the information is to be displayed,
the light of the sub-back light unit 23 is not transmitted toward
the partial area E1 by color filter 27. Therefore, from the fourth
embodiment, in addition to a similar effect to that of the prior
embodiments, the information is also clearly displayed. In a modification,
the light of the sub-back-light unit 23 may have a different wavelength
range from that of the light of the main back-light unit 22. Thus,
the color filter 28 may be omitted.
Finally, it will be understood by those skilled in the art that
the foregoing description is of preferred embodiments of the device,
and that various changes and modifications may be made to the present
invention without departing from the spirit and scope thereof.
The present disclosure relates to subject matters contained in
Japanese Patent Application No.10-160409 (filed on Jun. 9, 1998)
which is expressly incorporated herein, by reference, in its entirety. |