Digital Camera Patent Abstract
A digital camera having a taking lens, a finder for viewing light
transmitted through the taking lens, an image sensing element for
optoelectrically converting light which passes through the taking
lens, a light splitter capable of changing transmittance and dividing
the light transmitted through the taking lens to the image sensing
element and the finder, a light splitter driver for driving the
light splitter to a position to split the light between the image
sensing element and the viewfinder when viewing and driving the
light splitter to retract a position for directing the light only
to the image sensing element during photography, and a controller
for controlling the light splitter to a semi-transparent state to
direct light to the image sensing element and the viewfinder when
viewing and controlling the light splitter to a blocking state during
photography. Digital Camera Patent Claims
What is claimed is:
1. A camera comprising: a taking lens; an image sensor; a finder;
a light splitter which is movable between a first position to divide
light transmitted through the taking lens to the image sensor and
the finder and a second position in which the light splitter is
away from the light transmitted through the taking lens and the
light is directed only to the image sensor; a driver which moves
the light splitter to the first position and the second position;
and a controller which controls the light splitter to a semi-transparent
state in the first position and a blocking state in the second position.
2. A camera according to claim 1, wherein said light splitter is
a liquid crystal plate of variable transmittance.
3. A camera according to claim 1, wherein said light splitter provides
a liquid crystal plate having variable transmittance on a semi-transparent
mirror.
4. A camera according to claim 1, wherein said light splitter provides
a display which is able to display an image sensed by the image
sensor.
5. A camera according to claim 4, wherein said driver maintains
the light splitter at the second position for a specific time after
the image sensor senses the image and the display displays the image
sensed by the image sensor.
6. A camera according to claim 1, wherein said driver maintains
the light splitter at the second position when the sensor is continuously
sensing a plurality of images.
7. A camera according to claim 6, wherein said light splitter provides
a display which is able to display an image sensed by the image
sensor.
8. A camera according to claim 1, further comprising a return switch
which instructs the driver to move the light splitter from the second
position to the first position when the light splitter is at the
second position.
9. A method to control a splitter which is provided in a camera
and is movable between a first position to divide light transmitted
through a taking lens to an image sensor and a finder and a second
position in which the splitter is away from the light transmitted
through the taking lens and the light is directed only to the image
sensor, the method comprising the steps of: controlling the splitter
to a semi-transparent state in the first position; and controlling
the splitter to a blocking state in the second position.
10. A method according to claim 9, further comprising the step
of: displaying an image sensed by the image sensor on the splitter
when the splitter is in the second position.
Digital Camera Patent Description
This application is based on Patent Application No. HEI 11-373718
filed in Japan, the content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a camera of the single lens reflex
type using a semi-transparent mirror as a pop-up mirror, and specifically
relates to a digital camera of the single lens reflex type provided
with a pop-up semi-transparent mirror having a function of blocking
stray light entering the camera through the finder during photography.
2. Description of the Related Art
Although there are various types of cameras, in digital cameras
of the lens shutter type, an image to be photographed is not viewed
through the photographic optical system but rather is viewed through
a finder optical system provided separately. In this type of digital
camera, when the magnification ratio is increased and near range
imaging is performed, a problem arises insofar as the range of the
image viewed during image sensing and the image actually sensed
is shifted due to parallax. In order to eliminate this disadvantage
the single lens reflex type digital camera has been proposed.
Although there are various types of single lens reflex cameras,
such cameras typically use a totally reflective mirror as a pop-up
mirror. In this type of single lens reflex digital camera, the totally
reflective mirror is disposed at a position (finder viewing position)
inclined 45.degree. relative to the optical path while the photographer
is looking through the finder. Since the light passing through the
taking lens cannot reach the image sensing element when the totally
reflective mirror is set at the finder viewing position, disadvantages
arise insofar as autofocusing by the image sensing element, exposure
confirmation, and white balance adjustment cannot be performed.
Digital cameras of the single lens reflex type using a semi-transparent
mirror substituted for the aforesaid totally transparent mirror
have been proposed. In this type of single lens reflex digital camera,
light passing through the taking lens is normally split to the image
sensing element and the finder, but in this case further disadvantages
arise insofar as only one half the amount of light reaches the image
sensing element, thus darkening the image, and limiting the photographic
conditions.
A digital camera of the single lens reflex type using a semi-transparent
mirror as a pop-up mirror is proposed to eliminate these disadvantages.
A camera of this type is shown in FIG. 1. In FIG. 1, light passing
through a taking lens 1 is split in two so as to form light used
for image formation on a solid state image sensing element 3, and
light used for image viewing passing through an eyepiece finder
9. The photographer is able to view the image to be sensed through
the finder, and make various adjustments and settings based on the
image data collected by the solid state image sensing element 3.
Thereafter, when actually taking the photograph, a semi-transparent
mirror 2 springs upward in the arrow a direction to direct the entirety
of the light from the taking lens 1 to the solid state image sensing
element 3 for use in image sensing, as shown in FIG. 2. As a result,
the amount of light used is approximately double that when a prism
is used, making it difficult to restrict the photographic conditions,
and allowing photography under a broader range of photographic conditions.
Digital cameras of the single lens reflex type using a semi-transparent
mirror as a pop-up mirror have the further disadvantages listed
below.
As shown in FIG. 2, during daytime photography, the light from
the sun S enters the interior of the camera as harmful external
light, i.e., stray light, from the finder eyepiece 9, as indicated
by the arrow b. During photography, since the semi-transparent mirror
2 is set at the up position, after the stray light is transmitted
through the semi-transparent mirror 2, this light is reflected by
the interior wall surface of the camera body 20 and attains the
solid state image sensing element 3 Accordingly, this stray light
adversely affects the photographed image as ghost and flare, and
is the cause of exposure error. Particularly during photography
using the self timer, or during photography while viewing a liquid
crystal display 19 provided on the back of the camera body, the
stray light phenomenon becomes marked because the face of the photographer
is separated from the finder eyepiece 9 such that the face of the
photographer no longer covers the eyepiece 9.
When the semi-transparent mirror 2 is lifted during photography,
the light passing through the taking lens 1 is directed only to
the image sensing element 3, and is not directed to the finder,
such that as a natural result the photographer cannot see the image
through the finder when the photograph is taken. That is, the photographer
cannot directly confirm through the finder whether or not there
was an error in the image when the photograph is taken.
SUMMARY OF THE INVENTION
A main aspect of the art to be solved by the present invention
is to prevent stray light from the finder from reverse entry when
the pop-up semi-transparent mirror is lifted during photography,
in a digital camera of the single lens reflex type provided with
a pop-up semi-transparent mirror.
Another aspect of the art of the present invention is to allow
an image to be viewed through the finder even when the pop-up semi-transparent
mirror is lifted during photography.
These aspects of the art are resolved by the present invention
which provides a digital camera having the following construction.
The digital camera of the present invention comprises a taking
lens, a finder for viewing light transmitted through the taking
lens, an image sensing element for optoelectrically converting light
which passes through the taking lens, a light splitting means capable
of changing transmittance and dividing the light transmitted through
the taking lens to the image sensing element and the finder, a light
splitting means driving means for driving the light splitting means
to a position to split the light between the image sensing element
and the viewfinder when viewing and driving the light splitting
means to retract a position for directing the light only to the
image sensing element during photography, and a control means for
controlling the light splitting means to a semi-transparent state
to direct light to the image sensing element and the viewfinder
when viewing and controlling the light splitting means to a blocking
state during photography.
According to this construction, since the light splitting means
blocks the light when the light splitting means is moved to the
retracted position during photography, external light entering from
the finder eyepiece is prevented from advancing further into the
interior of the camera by the light splitting means. As a result,
the external light cannot advance to the image sensing element,
thereby preventing the generation of ghosts and flare.
The light splitting means comprises a liquid crystal plate of variable
transmittance.
The light splitting means provides the liquid crystal plate having
variable transmittance on a semi-transparent mirror.
It is desirable that the light splitting means displays an image
received from the image sensing element when in the retracted state.
It is desirable to have a continuous image sensing means for continuously
sensing a plurality of images, such that the light splitting means
drive means maintains the light splitting means at the retracted
position until continuous image sensing is completed.
It is desirable that the light splitting means drive means maintains
the light splitting means at the retracted position for a specific
time when the light splitting means is retracted to display a sensed
image.
It is desirable to have a light splitting means return indicator,
such that the light splitting means drive means returns the light
splitting means based on specification from the light splitting
means return indicator when the light splitting means is retracted.
These and other objects, advantages and features of the invention
will become apparent from the following description thereof taken
in conjunction with the accompanying drawings which illustrate specific
embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following description, like parts are designated by like
reference numbers throughout the several drawings.
FIG. 1 is a cross section view of the essential part of a conventional
digital camera;
FIG. 2 is a cross section view of the essential part of the conventional
digital camera of FIG. 1 illustrating the liquid crystal semi-transparent
mirror in the retracted state;
FIG. 3 is a cross section view of the essential part of an embodiment
of the digital camera of the present invention;
FIG. 4 is a cross section view of the essential part of the embodiment
of the digital camera of FIG. 3 illustrating the liquid crystal
semi-transparent mirror in the retracted state;
FIG. 5 is a block circuit diagram of an embodiment of the digital
camera of the present invention;
FIG. 6 is a cross section view of the essential part of another
embodiment of the digital camera of the present invention;
FIG. 7 is a cross section view of the essential part of the embodiment
of the digital camera of FIG. 6 illustrating the liquid crystal
semi-transparent mirror in the retracted state;
FIG. 8 is a flow chart during normal photography of the embodiment
of the digital camera of the present invention;
FIG. 9 is a flow chart of image display when the liquid crystal
semi-transparent mirror is at the retracted position in embodiment
of the digital camera of the present invention;
FIG. 10 is a flow chart of continuous photography in the embodiment
of the digital camera of the present invention;
FIG. 11 is a flow chart of automatic return of the semi-transparent
mirror to a non-display state after the liquid crystal semi-transparent
mirror displays an image for a specific time; and
FIG. 12 is a flow chart the semi-transparent mirror to the non-display
state by a return switch when the liquid crystal semi-transparent
mirror displays an image in embodiment of the digital camera of
the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The embodiments of the digital camera of the present invention
are described in detail hereinafter with reference to the accompanying
drawings.
FIG. 3 is a sectional view of the essential part of the digital
camera of the present invention, and differs from the conventional
construction shown in FIGS. 1 and 2 in that the normal semi-transparent
mirror is replaced by a liquid crystal semi-transparent mirror 22.
Reference number 20 in FIG. 3 refers to a camera body. On the front
surface of the camera body 20 is a taking lens 1, and on the back
surface are a finder 9 and a back liquid crystal display 19; on
the top surface is provided an image sensing button not shown in
the drawings.
A photographic optical system and finder optical system are housed
within the camera body 20.
The photographic optical system comprises a taking lens 1, stop
(iris) 7, shutter 8, liquid crystal semi-transparent mirror 22 as
a light splitting means, and a solid state image sensing element
3, which are arranged on the optical axis.
The finder optical system comprises a liquid crystal semi-transparent
mirror 22 finder reflective mirror 15, finder lens 4, and finder
eyepiece 9, such that the light from the taking lens 1 divided by
the liquid crystal semi-transparent mirror 22 is directed to the
eye E of the photographer.
The liquid crystal semi-transparent mirror 22 used as a light splitting
means may have various constructions. For example, a liquid crystal
plate having variable transmittance and a plurality of small pixels
may be used as the liquid crystal semi-transparent mirror 22. The
liquid crystal plate having variable transmittance changes from
a semi-transparent state to a non-transparent state by controlling
the voltage applied to each pixel. As a result, the liquid crystal
semi-transparent mirror 22 changes between a semi-transparent state
and a non-transparent state. That is, the pixel area of the non-transparent
state and the pixel area of the transmission state are approximately
uniformly dispersed, such that the applied voltage can be individually
controlled so as to have transmittance of the entire liquid crystal
plate set to the semi-transparent state. The entire liquid crystal
plate can be set to the semi-transparent state by controlling the
applied voltage such that the small pixels are set to the semi-transparent
state. In this way the semi-transparent state and non-transparent
state of the liquid crystal plate used as a light splitting means
can be changed by controlling the voltage applied to each pixel,
thereby effectively simplifying the light splitting means, rendering
it more compact, and achieving low power consumption.
The liquid crystal semi-transparent mirror 22 can be constructed
by providing a liquid crystal plate as described above the semi-transparent
mirror or on the semi-transparent mirror (i.e., on the finder side).
The liquid crystal semi-transparent mirror 22 can be constructed
by forming a semi-transparent film on the glass of a liquid crystal
plate. In a liquid crystal semi-transparent mirror 22 provided with
a liquid crystal plate having variable transmittance, the light
transmitting state of the liquid crystal plate can be changed by
controlling the voltage applied to each pixel of the liquid crystal
plate, and as a result the liquid crystal semi-transparent mirror
22 can be changed between a semi-transparent state and a non-transparent
state. Accordingly, since the liquid crystal semi-transparent mirror
22 can be changed between a semi-transparent state and a non-transparent
state by controlling the voltage applied to each pixel of the liquid
crystal plate, simplification, compactness, and low power consumption
of the light splitting means are effectively attained.
The liquid crystal semi-transparent mirror 22 is controlled so
as to normally operate as a semi-transparent mirror before the shutter
button is pressed and when image sensing ends. That is, the light
entering from the taking lens 1 passes through the stop 7 and the
shutter 8, and thereafter approximately one half the light is transmitted
through the liquid crystal semi-transparent mirror 22 and forms
an image on the solid state image sensing element 3. The remaining
one half of the light is reflected by the liquid crystal semi-transparent
mirror 22, reflected by the finder reflective mirror 15, and thereafter
is condensed by the finder lens 4 and forms an image on the eye
E of the photographer.
The liquid crystal semi-transparent mirror 22 is controlled by
the mirror drive circuit 12 and driven by the liquid crystal semi-transparent
mirror drive means 25 between a position inclined 45.degree. relative
to the optical axis at which it divides the light from the taking
lens 1 to the finder and the solid state image sensing element 3
(light splitting position) as shown in FIG. 3, and a position at
which it pops up and does not divide the light from the taking lens
to the finder (retracted position).
The liquid crystal semi-transparent mirror drive means 25 may take
various forms. For example, the liquid crystal semi-transparent
mirror drive means 25 shown in FIGS. 3 and 4 comprises a worm 25a
and a worm wheel 25b engaged thereto mounted on the tip of a drive
mechanism which rotates or advances by means of a solenoid, spring
charging mechanism or the like. In the liquid crystal semi-transparent
mirror drive means 25, the liquid crystal semi-transparent mirror
22 is connected to the worm wheel 25b so as to rotate integratedly
with the worm wheel 25b. Accordingly, when the operation switch
of the liquid crystal semi-transparent mirror drive means 25 is
turned ON, the liquid crystal semi-transparent mirror 22 set at
the position inclined at an angle of 45.degree. relative to the
optical axis, i.e., the light splitting position, shown in FIG.
3, is rotated on a rotational center of the rotating shaft of the
work wheel 25b, so as to be lifted in the arrow a direction to a
horizontal position relative to the optical axis, i.e., the retracted
position, as shown in FIG. 4.
The various operations of the camera are controlled by a microcomputer
10 as shown in FIG. 5. The microcomputer 10 controls an image processing
circuit 6 for processing the electrical signals from the solid state
image sensing element 3 (e.g., a charge coupled device), and the
light transmission state of the liquid crystal (full transparent
state, semi-transparent state, and non-transparent state) of the
liquid crystal semi-transparent mirror 22, and is connected to a
liquid crystal drive circuit 11 for displaying an image obtained
by the image processing circuit 6, a mirror drive circuit 12 for
driving at high speed the liquid crystal semi-transparent mirror
22 to a light splitting position and a retracted position, a shutter/iris
drive circuit 13 for controlling an optimum shutter speed and stop
value under the measured exposure conditions, an autofocus (AF)
circuit 14 for automatically adjusting the focus of the taking lens
1, and a back liquid crystal display 19 for displaying an image
obtained by the image processing circuit 6. The microcomputer 10
is also connected to a switch S1 for AF control of the taking lens
1, switch S2 for the exposure operation, and switch Sc for setting
the continuous photography mode. The switch S1 may also be used
as a switch for returning the photographic image displayed on the
liquid crystal semi-transparent mirror 22 to non display.
The operation of this digital camera is controlled by programs
stored in the microcomputer 10 and ROM (not illustrated) connected
thereto.
FIGS. 8.about.12 are flow charts of the various photographic modes.
FIG. 8 is a main flow chart showing the normal photographic mode
(first photographic mode); FIG. 9 is a flow chart of the mode for
displaying an image when the liquid crystal semi-transparent mirror
is set at the retracted position (second photographic mode); FIG.
10 is a flow chart of the continuous photographic mode (third photographic
mode); FIG. 11 is a flow chart of a mode for automatically returning
the liquid crystal semi-transparent mirror displaying an image to
a non-display state after a specified time has elapsed (fourth photographic
mode); FIG. 12 is a flow chart of a mode for returning an image
displayed on the liquid crystal semi-transparent mirror to a non-display
state using the return switch (fifth photographic mode).
The first photographic mode of the digital camera of a first embodiment
is described below with reference to FIGS. 3, 4, 5, and 8.
Before sensing an image, the liquid crystal semi-transparent mirror
22 is maintained inclined 45.degree. relative to the optical axis
at the light splitting position as shown in FIG. 3. The liquid crystal
semi-transparent mirror 22 comprising a liquid crystal plate enters
a semi-transparent state by individually controlling the voltage
applied to each pixel, and approximately one half of the incidence
light is transmitted and approximately one half of the remaining
light is reflected as in a conventional semi-transparent mirror.
That is, approximately one half of the light passing through the
taking lens 1 is transmitted through the liquid crystal semi-transparent
mirror 22 and is directed onto the solid state image sensing element
3. The remaining one half light is reflected upward by the liquid
crystal semi-transparent mirror 22, and this reflected light is
reflected by a finder mirror 15, passes through the finder lens
4, and is directed to the finder eyepiece 9.
When the shutter button is lightly pressed (half depressed) for
photographic preparation, the switch S1 is closed, and after image
data from the solid state image sensing element 3 are input to the
microcomputer 10, an optimum exposure is determined by calculation
in accordance with a specific calculation method. The optimum parameters
including stop 7 aperture diameter, shutter 8 speed, white balance
value and the like are determined based on this exposure value.
When part of the taking lens 1 is driven slightly in the optical
axis direction, the degree of focus is evaluated based on the image
data obtained by the image sensing element 3. Then, the focus is
adjusted by moving a part of the taking lens 1 to a focus position
based on the evaluation value. At the same time, part of the light
transmitted through taking lens 1 is reflected by the liquid crystal
semi-transparent mirror 22 and thereafter passes through the finder
lens 4 and is directed to the finder eyepiece 9 as previously described,
such that the photographer is able to confirm in real-time the image
to be photographed through the finder eyepiece 9. At this time the
same image as that confirmed by the finder is displayed on the back
liquid crystal display 19 provided on the back side of the camera
body 20.
Thereafter, when the photographer presses the shutter button (full
depression), the switch S2 is closed, and the main photographic
mode is entered.
When the main photographic mode is entered, the motor is actuated
in the liquid crystal semi-transparent mirror drive means 25 to
rotate the edge of the liquid crystal semi-transparent mirror 22
on the taking lens 1 side in the arrow a direction, i.e., upward,
about the rotational axis of the worm wheel 25b mounted on the liquid
crystal semi-transparent mirror 22. The liquid crystal semi-transparent
mirror 22 pops up and is maintained in a horizontal state, i.e.,
at the retracted position, as shown in FIG. 4 (#110). At this time
the liquid crystal semi-transparent mirror 22 set at the completely
retracted position is confirmed by a position detection means of
the liquid crystal semi-transparent mirror 22 not illustrated. Thereafter,
the liquid crystal drive circuit 11 is actuated by a signal from
the microcomputer 10 to drive the liquid crystal plate to enter
the non-transparent state, and the liquid crystal semi-transparent
mirror 22 enters the non-transparent state (#112). As a result,
even though stray light indicated by the arrow b enters the interior
of the camera body 20 through the finder eyepiece 9, the stray light
is blocked by the liquid crystal semi-transparent mirror 22 as shown
in FIG. 4. Accordingly, stray light from outside the camera is prevented
from entering the interior of the camera body 20 by the liquid crystal
semi-transparent mirror 22, such that stray light does not enter
the image sensing element 3.
As shown in FIG. 4, when the liquid crystal semi-transparent mirror
22 pops up in the non-transparent state, the stop 7 opens and the
digital camera takes a photograph at shutter speed based on the
optimized exposure conditions as described above (#114). At this
time all the light passing through the taking lens 1 is directed
to the image sensing element 3 for use in photography, thereby enlarging
the photographic range.
When the photograph is completed, the liquid crystal drive circuit
11 is actuated to set the liquid crystal semi-transparent mirror
22 to the semi-transparent/semi-reflective state by a signal from
the microcomputer 10 (#116). Thereafter, a motor in the liquid crystal
semi-transparent mirror drive means 25 is actuated in the reverse
direction, and the liquid crystal semi-transparent mirror 22 is
again maintained at the light splitting position (mirror down position)
at an inclination of 45.degree. relative to the optical axis as
shown in FIG. 3 (#118).
When using a liquid crystal plate having variable transmittance
as a liquid crystal semi-transparent mirror, the semi-transparent
state and transparent state of the liquid crystal semi-transparent
mirror 22 can be set by individually controlling the voltage applied
to each pixel of the liquid crystal. Furthermore, a control method
may be used to apply a specific voltage in a batch to all pixels
of the liquid crystal plate. In this instance when using batch control
of the voltage applied to set the transparent and non-transparent
state of the liquid crystal plate, the semi-transparent mirror equipped
liquid crystal semi-transparent mirror 22 may respectively be set
to semi-transparency and non-transparency. Accordingly, the method
of batch control of the applied voltage is a simpler control method
compared to individually controlling the applied voltages, thereby
simplifying the control circuit.
The second photographic mode of the digital camera of the first
embodiment is described below with reference to FIGS. 3, 4, 5, and
9.
In the second photographic mode, a digital camera is used which
has a construction largely similar to that used in the first photographic
mode, although image data from the image sensing element 3 are displayed
on the liquid crystal plate. At this time the liquid crystal plate
may use a TN-type liquid crystal or TFT-type liquid crystal, and
may be a black and white display or a color display.
FIG. 9 is a flow chart of the mode for displaying an image on the
liquid crystal semi-transparent mirror 22 set at the retracted position.
First, the liquid crystal semi-transparent mirror 22 is set at the
light splitting position shown in FIG. 3, the switch S1 is closed
when the shutter button is pressed halfway for preliminary photography,
the light directed to the image sensing element 3 is photoelectrically
converted, and preliminary photographic image data are formed by
the image processing circuit 6. The photographic conductions are
set based on the image data. Then, the switch S2 is closed when
the shutter button is fully pressed, the camera enters the main
photographic mode, and the liquid crystal semi-transparent mirror
22 is moved to the retracted position as shown in FIG. 4 (#120).
Directly thereafter, the image from the taking lens 1 cannot be
viewed from the finder, the liquid crystal drive circuit 11 is actuated
by a signal from the microcomputer 10, and the image data are displayed
on the liquid crystal plate of the liquid crystal semi-transparent
mirror 22 (#122). At this time the same image as confirmed on the
finder is displayed on the back liquid crystal display 19 provided
on the back of the camera body 20 by the image data from the image
sensing element 3.
Then, the photographic operation described in the first photographic
mode is executed (#124), and when the photograph has been completed
(#124), the image display is erased by a signal from the microcomputer
10, and the liquid crystal semi-transparent mirror 22 is driven
by the liquid crystal drive circuit 11 to enter the semi-transparent/semi-reflective
state (#126). That is, the display of the image occurs for a short
time from after the mirror pops up until the liquid crystal semi-transparent
mirror 22 returns to the light splitting position. Thereafter, the
liquid crystal semi-transparent mirror 22 is again maintained at
the light splitting position (mirror down position) inclined 45.degree.
relative to the optical axis by the liquid crystal semi-transparent
mirror drive means 25 as shown in FIG. 3 (#128). The photographed
image is displayed on the back liquid crystal display 19 provided
on the back of the camera body 20. In this photographic mode, the
photo image normally can be confirmed through the finder, and a
sense of security is obtained because there is no blackout.
The third photographic mode of the digital camera of the first
embodiment is described below with reference to FIGS. 3, 4, 5, and
10. In the third photographic mode, the digital camera used is identical
to the camera used in the second photographic mode.
FIG. 10 is a flow chart of a mode for continuous photography and
displaying an image on the liquid crystal semi-transparent mirror
22 set at the refracted position. First, the liquid crystal semi-transparent
mirror 22 is set at the light splitting position shown in FIG. 3,
and after the switch Sc is set to ON to set the continuous photo
mode as preparation for photography, the number of continuous photographs
is set. When the shutter button is pressed halfway, the switch S1
is closed, light from the taking lens 1 is photoelectrically converted
by the image sensing element 3, and image data are formed by the
image processing circuit 6. The photographic conditions are set
based on the image data. Then, the switch S2 is closed when the
shutter button is fully pressed, the camera enters the photographic
mode, and the liquid crystal semi-transparent mirror 22 is moved
to the retracted position as shown in FIG. 4 (#140). Directly thereafter,
the image from the taking lens 1 cannot be viewed from the finder,
the liquid crystal drive circuit 11 is actuated by a signal from
the microcomputer 10, and the image data are displayed on the liquid
crystal plate of the liquid crystal semi-transparent mirror 22 (#142).
At this time the same image as confirmed on the finder is displayed
on the back liquid crystal display 19 provided on the back of the
camera body 20 by the image data from the image sensing element
3. Then, the photographic operation is executed (#144), and a determination
is made as to whether or not the set specified number of photographs
have been taken (#146). If the specified number of photographs have
not been taken, continuous photography continues with the liquid
crystal semi-transparent mirror 22 maintained in the retracted position
until the specified number of photographs have been taken. Alternately,
in step #146, the continuous photographing may execute as long as
switch S2 is closed instead of based on the specified number of
photographs having been taken.
When continuous photography ends, the display of the image is erased
by a signal from the microcomputer 10, and the liquid crystal drive
circuit is actuated to set the liquid crystal semi-transparent mirror
22 in the semi-transparent/semi-reflective state (#148). That is,
the display of the image occurs for a short time in accordance with
the number of continuous photographs from after the mirror pops
up until the liquid crystal semi-transparent mirror 22 returns to
the light splitting position. Thereafter, the liquid crystal semi-transparent
mirror 22 is again maintained at the light splitting position (mirror
down position) inclined 45.degree. relative to the optical axis
by the liquid crystal semi-transparent mirror drive means 25 as
shown in FIG. 3 (#150). In the continuous photographic mode, continuous
photography is executed with the liquid crystal semi-transparent
mirror 22 maintained at the retracted position by the liquid crystal
mirror drive means 25. Accordingly, high speed continuous photography
is possible because the liquid crystal semi-transparent mirror 22
does not move physically during continuous photography compared
to when the liquid crystal semi-transparent mirror 22 moves reciprocatingly
between the light splitting position and the retracted position
during continuous photography, thereby improving the reliability
of the continuous photography system, and reducing the power consumption.
Furthermore, the desirability of the photographic image with regard
to smearing, luminance, color, focus and the like can be confirmed
through the finder. As a result, since unnecessary images are not
photographed, photo errors are reduced, and image storage memory
is conserved. Furthermore, since the image can be confirmed by peering
into the finder alone for both preliminary photography and main
photography, moving the line of sight relative to the finder and
the back liquid crystal display 19 before and after photography
becomes unnecessary, and makes the photographic operation extremely
comfortable. In addition, when the display to the liquid crystal
is continuously switched in conjunction with continuous photography,
the object image can be continuously confirmed in the finder since
the object image to be photographed is displayed.
The fourth photographic mode of the digital camera of the first
embodiment is described below with reference to FIGS. 3, 4, 5, and
11. In the fourth photographic mode, the digital camera used has
the same construction as the camera used in the second photographic
mode.
FIG. 11 is a flow chart of the mode for displaying a main photographic
image for a specified time on the liquid crystal semi-transparent
mirror 22 set at the retracted position. First, the liquid crystal
semi-transparent mirror 22 is set at the light splitting position,
and the photographer sets the image display time beforehand. The
switch S1 is closed when the shutter button is pressed halfway for
preliminary photography, the light directed to the image sensing
element 3 is photoelectrically converted, and image data are formed
by the image processing circuit 6. The photographic conditions are
set based on the image data. Then, the switch S2 is closed when
the shutter button is fully pressed, the camera enters the main
photographic mode, and the liquid crystal semi-transparent mirror
22 is moved to the retracted position as shown in FIG. 4 (#160).
Directly thereafter, the image from the taking lens 1 cannot be
viewed from the finder, the liquid crystal drive circuit 11 is actuated
by a signal from the microcomputer 10, and the image data are displayed
on the liquid crystal plate of the liquid crystal semi-transparent
mirror 22 (#162). At this time the same image as confirmed on the
finder is displayed on the back liquid crystal display 19 provided
on the back of the camera body 20 by the image data from the image
sensing element 3. When main photography (#164) ends, the photographed
image is displayed on the liquid crystal semi-transparent mirror
22 (#166). Then a determination is made as to whether or not the
photographed image has been displayed the specified time (#168).
If the specified time has not elapsed, the display on the liquid
crystal semi-transparent mirror 22 continues. At this time the same
image as confirmed on the finder is displayed on the back liquid
crystal display 19 provided on the back of the camera body 20 by
the image data from the image sensing element 3.
When the main photography image has been displayed the specified
time, the display of the image is erased by a signal from the microcomputer
10, and the liquid crystal drive circuit 11 is actuated to set the
liquid crystal semi-transparent mirror 22 in the semi-transparent/semi-reflective
state (#170). That is, the display of the image occurs for a set
specified time after the mirror pops up until the liquid crystal
semi-transparent mirror 22 returns to the light splitting position.
Thereafter, the liquid crystal semi-transparent mirror 22 is again
maintained at the light splitting position (mirror down position)
inclined 45.degree. relative to the optical axis by the liquid crystal
semi-transparent mirror drive means 25 as shown in FIG. 3 (#172).
In the main photographic image display mode, since the main photographic
image is displayed on the liquid crystal semi-transparent mirror
22 for an optional set time, the desirability of the photographic
image with regard to smearing, luminance, color, focus and the like
can be confirmed through the finder any time during the set time.
As a result, since unnecessary images are not photographed, photo
errors are reduced, and image storage memory is conserved. Furthermore,
since the image can be confirmed by peering into the finder alone
for both preliminary photography and main photography, moving the
line of sight relative to the finder and the back liquid crystal
display 19 before and after photography becomes unnecessary, and
makes the photographic operation extremely comfortable.
The fifth photographic mode of the digital camera of the first
embodiment is described below with reference to FIGS. 3, 4, 5, and
12. The digital camera used in the fifth photographic mode is identical
to the camera of the second photographic mode.
FIG. 12 is a flow chart of the mode for displaying a main photographic
image on the liquid crystal semi-transparent mirror 22 set at the
retracted position, and during this display time returning to the
non-display state by pressing the return switch S1. First, the liquid
crystal semi-transparent mirror 22 is set at the light splitting
position shown in FIG. 3. The switch Si is closed when the shutter
button is pressed halfway, the light directed to the image sensing
element 3 is photoelectrically converted, and image data are formed
by the image processing circuit 6. The photographic conditions are
set based on the image data. Then, the switch S2 is closed when
the shutter button is fully pressed, the camera enters the main
photographic mode, and the liquid crystal semi-transparent mirror
22 is moved to the retracted position as shown in FIG. 4 (#180).
Directly thereafter, the image from the taking lens 1 cannot be
viewed from the finder, the liquid crystal drive circuit 11 is actuated
by a signal from the microcomputer 10, and the image data are displayed
on the liquid crystal plate of the liquid crystal semi-transparent
mirror 22 (#182). At this time the same image as confirmed on the
finder is displayed on the back liquid crystal display 19 provided
on the back of the camera body 20 by the image data from the image
sensing element 3. When main photography (#184) ends, the photographed
image is displayed on the liquid crystal semi-transparent mirror
22 (#186). Then a determination is made as to whether or not the
return switch S1 has been pressed (#188). If the return switch S1
has not been pressed, a check is made to determine whether or not
the main photographic image has been displayed the specified time
(#189). Since the display continues if the return switch SI is not
pressed, the liquid crystal semi-transparent mirror 22 is forcibly
returned when the specified time (the specified time may be set
in the camera beforehand, or may be set by the photographer) has
elapsed. If the specified time has not elapsed, the main photography
image is displayed on the liquid crystal semi-transparent mirror
22. If the specified time has elapsed, the photographic image displayed
on the liquid crystal semi-transparent mirror 22 is discontinued,
and the process advances to the next step. However, if the photographer
presses the return switch S1 during image display, the process advances
to the next step. At this time the same image as confirmed on the
finder is displayed on the back liquid crystal display 19 provided
on the back of the camera body 20 by the image data from the image
sensing element 3.
Next, the liquid crystal drive circuit 11 is actuated to set the
liquid crystal semi-transparent mirror 22 to the semi-transparent/semi-reflective
state by a signal from the microcomputer 10 (#190). That is, the
image is displayed from after the mirror pops up until the liquid
crystal semi-transparent mirror 22 returns to the light splitting
position, until the switch S1 is pressed, or for the specified time
if the switch S1 is not pressed. Thereafter, the liquid crystal
semi-transparent mirror drive means 25 is actuated, and the liquid
crystal semi-transparent mirror 22 is again maintained at the light
splitting position (mirror down position) at an inclination of 45.degree.
relative to the optical axis as shown in FIG. 3 (#192). In this
photographic mode, the liquid crystal semi-transparent mirror 22
displaying the main photographic image is returned from the display
state to the non-display state by a timing optionally selected by
the photographer, then moved to the next photograph. Accordingly,
the desirability of the photographic image with regard to smearing,
luminance, color, focus and the like can be confirmed through the
finder. As a result, since unnecessary images are not photographed,
photo errors are reduced, and image storage memory is conserved.
Furthermore, since the image can be confirmed by peering into the
finder alone for both preliminary photography and main photography,
moving the line of sight relative to the finder and the back liquid
crystal display 19 before and after photography becomes unnecessary,
and makes the photographic operation extremely comfortable. Although
the switch S1 is used as the return means of the liquid crystal
semi-transparent mirror 22, the present invention is not limited
to this arrangement inasmuch as a separate member, for example,
also may be provided.
Another embodiment of the digital camera is described below with
reference to FIGS. 6 and 7.
FIG. 6 is a cross section view of the essential part of a digital
camera of another embodiment of the present invention, and shows
the liquid crystal semi-transparent mirror 22 set at the light splitting
position. FIG. 7 is a cross section view showing the liquid crystal
semi-transparent mirror of FIG. 6 set at the retracted position.
The embodiment of the digital camera shown in FIGS. 6 and 7 is basically
similar in construction to the camera of the first embodiment, but
differs from the first embodiment in that the back liquid crystal
display 19 is not provided on the back side of the camera body 20.
The digital camera of this embodiment is capable of photography
in accordance with the first through fifth photographic modes identical
to those described for the digital camera of the first embodiment.
Since the digital camera of this embodiment is not provided with
a back liquid crystal display 19, the image captured by the image
sensing element 3 is displayed entirely on the liquid crystal semi-transparent
mirror 22 set at the retracted position. Accordingly, in the second
through fifth photographic modes described for the digital camera
of the first embodiment, the preliminary photographic image and
the main photographic image are both displayed on the liquid crystal
plate of the liquid crystal semi-transparent mirror 22 set at the
retracted position, and the photographer observes only this display
image. Since the back liquid crystal display 19 is not provided,
the digital camera is more compact and lighter weight, and has reduced
power consumption. Furthermore, since the photographer looks only
through the finder during photography, the photographer can concentrate
on the photography such that photographic errors are reduced. |