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Digital Camera Patent Abstract
In a lens-interchangeable digital camera having a half mirror arranged
in a shooting optical path and capable of displaying a live view,
the half mirror is made movable between a position inserted into
the shooting optical path and a position retracted from the shooting
optical path, and when power-on is detected, the movable half mirror
is returned to the position in the shooting optical path, while
when power-off is detected, the movable half mirror is retracted
from the shooting optical path. Further, upon detecting the mounting
state of a lens barrel, when removal of the lens barrel is detected,
the movable half mirror is retracted, while when mounting of the
lens barrel is detected, the movable half mirror is returned.
Digital Camera Patent Claims
1. A lens-interchangeable digital camera capable of removably mounting
a photographing lens, the digital camera comprising:a mirror member
capable of being moved in and out of an optical path of the photographing
lens and having properties to reflect part of a subject light beam
and transmit the remaining part of the subject light beam in the
optical path;a drive mechanism for moving the mirror member into
or out of the optical path of the photographing lens;a focus detection
sensor for receiving a light beam reflected by the mirror member
to detect a focus state of the photographing lens when the mirror
member is located in the optical path;an image pickup device for
receiving the subject light beam transmitted through the mirror
member to output a subject image signal when the mirror member is
located in the optical path;an electronic finder for displaying
the subject image signal output from the image pickup device; anda
control circuit for stopping the display operation of the electronic
finder and retracting the mirror member from the optical path of
the photographing lens when the photographing lens is removed while
the display operation of the electronic finder is being performed.
2. The digital camera according to claim 1 wherein when the digital
camera is brought into a non-operating state while the display operation
of the electronic finder is being performed, the control circuit
stops the display operation of the electronic finder and retracts
the mirror member from the optical path of the photographing lens.
3. The digital camera according to claim 2 wherein if the photographing
lens is mounted upon shifting the digital camera from the non-operating
state to an operating state, the control circuit moves the mirror
member into the optical path of the photographing lens to start
the display operation of the electronic finder.
4. The digital camera according to claim 1 wherein when the photographing
lens is remounted, the control circuit moves the mirror member back
into the optical path of the photographing lens to restart the display
operation of the electronic finder.
5. The digital camera according to claim 1 wherein the mirror member
is a thin-film mirror or a glass mirror with a thickness of 0.2
mm or less.
6. The digital camera according to claim 1 wherein when an operation
for changing an operation mode of the digital camera is performed
while the display operation of the electronic finder is being performed,
the control circuit stops the display operation of the electronic
finder.
7. The digital camera according to claim 1 wherein the retracted
position of the mirror member is a position where a light-receiving
window of the focus detection sensor is covered by the mirror member.
8. A lens-interchangeable digital camera capable of removably mounting
a photographing lens, the digital camera comprising:a mirror member
capable of being moved in and out of an optical path of the photographing
lens and having properties to reflect part of a subject light beam
and transmit the remaining part of the subject light beam in the
optical path;a drive mechanism for moving the mirror member into
or out of the optical path of the photographing lens;a light-receiving
sensor for receiving a light beam transmitted through or reflected
by the mirror member to output a subject image signal when the mirror
member is located in the optical path; anda control circuit for
stopping the signal output operation of the light-receiving sensor
and moving the mirror member out of the optical path of the photographing
lens when the photographing lens is removed.
9. The digital camera according to claim 8 wherein the mirror member
is a thin-film mirror or a glass mirror with a thickness of 0.2
mm or less.
10. The digital camera according to claim 8 wherein when the digital
camera is brought into a non-operating state, the control circuit
stops the signal output operation of the light-receiving sensor
and retracts the mirror member from the optical path of the photographing
lens.
11. The digital camera according to claim 10 wherein if the photographing
lens is mounted upon shifting the digital camera from the non-operating
state to an operating state, the mirror member is moved into the
optical path of the photographing lens to allow the signal output
operation of the light-receiving sensor.
12. The digital camera according to claim 10 wherein when the photographing
lens is remounted, the mirror member is moved back into the optical
path of the photographing lens to allow the signal output operation
of the light-receiving sensor.
13. The digital camera according to claim 8 wherein the light-receiving
sensor is an image pickup device or a focus detection sensor.
14. A lens-interchangeable digital camera capable of removably
mounting a photographing lens, the digital camera comprising:a mirror
member capable of being moved in and out of an optical path of the
photographing lens and having properties to reflect part of a subject
light beam and transmit the remaining part of the subject light
beam in the optical path;a drive mechanism for moving the mirror
member into or out of the optical path of the photographing lens;a
light-receiving sensor for receiving a light beam transmitted through
or reflected by the mirror member to output a subject image signal
when the mirror member is located in the optical path; anda control
circuit for moving the mirror member out of the optical path of
the photographing lens and stopping the operation of the light-receiving
sensor in such a state that the photographing lens has been removed.
15. The digital camera according to claim 14 wherein the mirror
member is a thin-film mirror or a glass mirror with a thickness
of 0.2 mm or less.
16. A lens-interchangeable digital camera capable of removably
mounting a photographing lens, the digital camera comprising:a mirror
member capable of being moved in and out of an optical path of the
photographing lens, the mirror member being a thin-film mirror or
a glass mirror with a thickness of 0.2 mm or less and having a property
to reflect part of incident light; anda control part for moving
the mirror member to a predetermined retracted position when the
photographing lens is removed,wherein the retracted position is
a position where the mirror member is less likely to interfere with
an extraneous material entering from an opening of a lens mount
part.
17. A control method for a lens-interchangeable camera for capturing
a subject image through a mirror member to enable displaying of
a moving picture based on the captured subject image, the mirror
member capable of being moved in and out of an optical path of a
photographing lens and having a light-transmissive property, the
control method comprising the steps of:stopping the moving picture
display and moving the mirror member out of the optical path of
the photographing lens when removal of the photographing lens is
detected while the moving picture is being displayed; andmoving
the mirror member back into the optical path and restarting the
moving picture display when remounting of the photographing lens
is detected.
Digital Camera Patent Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001]This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2006-150965
and 2006-150966 filed on May 31, 2006, the entire contents of which
are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002]1. Field of the Invention
[0003]The present invention relates to a lens-interchangeable digital
camera having a so-called electronic finder function (also referred
to as a live-view display function) for displaying an image acquired
by an image pickup device on a display device as a moving image.
[0004]2. Description of the Related Art
[0005]While the traditional digital camera was designed to view
a subject image through an optical finder, a growing number of recent
digital cameras have eliminated the optical finder and incorporated
an electronic finder function for displaying an image acquired by
an image pickup device continuously on a display device such as
an LCD monitor for subject image viewing.
[0006]As a digital camera having such an electronic finder display
function, a lens-interchangeable camera is disclosed, for example,
in Japanese Patent Application Laid-Open No. 2002-369042. In the
lens-interchangeable camera, a movable mirror is retracted from
a shooting optical path and a focal-plane shutter is fully opened
to guide a subject image to an image pickup device, thereby displaying
a subject image acquired by the image pickup device continuously
on the LCD monitor.
[0007]Further, Japanese Patent Application Laid-Open No. 2002-6208
proposes a digital camera having a movable mirror formed into a
half mirror so that part of a subject light beam that passed through
a photographing optical system will be transmitted through the half
mirror to reach an image pickup device and the remaining part of
the subject light beam will be reflected to reach a phase-difference
AF sensor. According to this structure, the phase-difference AF
is enabled while providing an electronic finder display.
BRIEF SUMMARY OF THE INVENTION
[0008]According to the invention of the present application, a
movable half mirror is made movable between a position inserted
into a shooting optical path and a position retracted from the shooting
optical path, and when power-on is detected, the movable half mirror
is returned to the position in the shooting optical path, while
when power-off is detected, the movable half mirror is retracted.
Further, upon detecting the mounting state of a lens barrel, when
removal of the lens barrel is detected, the movable half mirror
is retracted, while when mounting of the lens barrel is detected,
the movable half mirror is returned.
[0009]One aspect of the present invention is to provide a lens-interchangeable
digital camera capable of removably mounting a photographing lens,
the digital camera comprising: a mirror member capable of being
moved in and out of the optical path of the photographing lens and
having properties to reflect part of a subject light beam and transmit
the remaining part of the subject light beam in the optical path;
a drive mechanism for moving the mirror member into or out of the
optical path of the photographing lens; a focus detection sensor
for receiving a light beam reflected by the mirror member to detect
the focus state of the photographing lens when the mirror member
is located in the optical path; an image pickup device for receiving
the subject light beam transmitted through the mirror member to
output a subject image signal when the mirror member is located
in the optical path; an electronic finder for displaying the subject
image signal output from the image pickup device; and a control
circuit for stopping the display operation of the electronic finder
and retracting the mirror member from the optical path of the photographing
lens when the photographing lens is removed while the display operation
of the electronic finder is being performed.
[0010]Another aspect of the present invention is to provide a lens-interchangeable
digital camera capable of removably mounting a photographing lens,
the digital camera comprising: a mirror member capable of being
moved in and out of the optical path of the photographing lens and
having properties to reflect part of a subject light beam and transmit
the remaining part of the subject light beam in the optical path;
a drive mechanism for moving the mirror member into or out of the
optical path of the photographing lens; a light-receiving sensor
for receiving a light beam transmitted through or reflected by the
mirror member to output a subject image signal when the mirror member
is located in the optical path; and a control circuit for stopping
the signal output operation of the light-receiving sensor and moving
the mirror member out of the optical path of the photographing lens
when the photographing lens is removed.
[0011]Still another aspect of the present invention is to provide
a lens-interchangeable digital camera capable of removably mounting
a photographing lens, the digital camera comprising: a mirror member
capable of being moved in and out of the optical path of the photographing
lens and having properties to reflect part of a subject light beam
and transmit the remaining part of the subject light beam in the
optical path; a drive mechanism for moving the mirror member into
or out of the optical path of the photographing lens; a light-receiving
sensor for receiving a light beam transmitted through or reflected
by the mirror member to output a subject image signal when the mirror
member is located in the optical path to output; and a control circuit
for moving the mirror member out of the optical path of the photographing
lens and stopping the operation of the light-receiving sensor in
such a state that the photographing lens has been removed.
[0012]Yet another aspect of the present invention is to provide
a lens-interchangeable digital camera capable of removably mounting
a photographing lens, the digital camera comprising: a mirror member
capable of being moved in and out of the optical path of the photographing
lens and having a property to reflect part of incident light, the
mirror member being a thin-film mirror or a glass mirror with a
thickness of 0.2 mm or less; and a control part for moving the mirror
member to a predetermined retracted position when the photographing
lens is removed, wherein the retracted position is a position where
the mirror member is less likely to interfere with an extraneous
material entering from an opening of a lens mount part.
[0013]Yet another aspect of the present invention is to provide
a control method for a lens-interchangeable camera for capturing
a subject image through a mirror member to enable displaying of
a moving picture based on the captured subject image, the mirror
member capable of being moved in and out of the optical path of
a photographing lens and having a light-transmissive property, the
control method comprising the steps of:
[0014]stopping the moving picture display and moving the mirror
member out of the optical path of the photographing lens when removal
of the photographing lens is detected while the moving picture is
being displayed; and moving the mirror member back into the optical
path and restarting the moving picture display when remounting of
the photographing lens is detected.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0015]These and other features, aspects, and advantages of the
apparatus and methods of the present invention will become better
understood with regard to the following description, appended claims,
and accompanying drawings where:
[0016]FIG. 1 an exterior perspective view of a digital camera according
to a preferred embodiment of the present invention as viewed from
its backside;
[0017]FIG. 2 is a block diagram showing the general structure of
an electric system of the digital camera according to the preferred
embodiment to which the present invention is applied;
[0018]FIG. 3 is a perspective view showing the structure of components
of a movable half mirror according to the preferred embodiment of
the present invention;
[0019]FIG. 4 is a flowchart showing a power-on reset operation
according to the preferred embodiment of the present invention;
[0020]FIG. 5 is a flowchart of a shooting operation according to
the preferred embodiment of the present invention; and
[0021]FIG. 6 contains schematic views showing the structure of
a mounting/demounting detection switch according to the preferred
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022]A preferred embodiment of the invention is described below
with reference to the accompanying drawings.
[0023]The preferred embodiment is described below using a digital
camera to which the present invention is applied.
[0024]FIG. 1 is an exterior perspective view of the digital camera
according to the embodiment of the present invention as viewed from
its backside. This camera consists principally of a camera body
20 and a lens barrel 10 as an interchangeable photographing lens.
The lens barrel 10 is removably mounted on a mount opening portion
(not shown) provided on the front of the camera body 20. A subject
light beam from the photographing lens composed of lenses 101a,
101b, etc. (see FIG. 2) is guided into the camera body 20 through
the mount opening portion. In the embodiment, the lens barrel 10
and the camera body 20 are constructed separately and electrically
connected through a communication contact 300 (see FIG. 2). Further,
a mounting/demounting detection switch 259 (see FIG. 2) is provided
in the camera body 20 to enable detection of the mounting state
of the lens barrel 10 on the camera body 20 (as to whether the lens
barrel 10 is mounted on the camera body 20 properly, i.e., whether
the lens barrel 10 is detached from the camera body 20).
[0025]A release button 21, a mode dial 22, a power switch lever
23, a control dial 24, etc. are arranged on the top face of the
camera body 20. The release button 21 has a first release switch
to be turned on when a camera user presses the release button 21
halfway and a second release switch to be turned on when the camera
user fully presses the release button 21. When this first release
switch (hereinafter abbreviated as "1R") is turned on,
the camera performs shooting preparation operations, such as focus
detection, focusing of the photographing lens, measuring subject
brightness, etc. Then, when the second release switch (hereinafter
abbreviated as "2R") is turned on, the camera performs
a shooting operation for capturing image data of a subject image
based on the output of a CCD (Charge Coupled Device) 221 (see FIG.
2) as an image pickup device.
[0026]The mode dial 22 is a rotatable operating member. The mode
dial 22 can be set to any pictorial indication or letter symbol
provided on the mode dial 22 to indicate each shooting mode in order
to select the set shooting mode. The shooting modes include a full-auto
shooting mode (AUTO), a program shooting mode (P), an aperture priority
shooting mode (A), a shutter speed priority shooting mode (S), a
manual shooting mode (M), a portrait shooting mode, a landscape
shooting mode, a macro shooting mode, a sport shooting mode, a night
scene shooting mode, etc. The power switch lever 23 is an operating
member to power on or off the digital camera (i.e., an operating
member to shift the digital camera from a non-operating state to
an operating state, or vice versa). The power switch lever 23 is
rotatable between two positions, namely on and off positions. The
control dial 24 is a rotatable operating member. When the control
dial 24 is turned on an information display screen or the like,
a desired setting value, mode, or the like can be selected.
[0027]On the back face of the camera body 20, a rear LCD monitor
26, a playback button 27, a menu button 28, an arrow pad 30, an
OK button 31, and a finder eyepiece part 33 are arranged. The rear
LCD monitor 26 is a display device functioning as an electronic
finder to provide a display for subject image viewing, for playback-displaying
shot subject images, and for displaying camera information or a
menu. The display device is not limited to the LCD as long as it
can display all of the above. The display device can also be such
that its inclination angle can be changed at will with respect to
the camera body 20. The finder eyepiece part 33 is an eyepiece window
for viewing a subject image, and an intra-finder LCD monitor 29
to be described later is arranged in the finder eyepiece part 33,
allowing the camera user to view the subject image through this
finder eyepiece part 33. The playback button 27 is an operation
button to instruct the camera to display a subject image recorded
after shot on the rear LCD monitor 26. In response to actuation
of the playback button 27, image data of a subject compressed in
JPEG or the like and stored in an SDRAM 238 or recording medium
245 to be described later is decompressed and displayed on the rear
LCD monitor 26.
[0028]The arrow pad 30 is an operating member to instruct the movement
of a cursor two-dimensionally in the X and Y directions on the rear
LCD monitor 26. The arrow pad 30 is also used to select an image
recorded on the recording medium 245 and to be played back upon
displaying a subject image. Instead of providing four buttons, namely
UP, DOWN, RIGHT, and LEFT buttons, the arrow pad 30 can be replaced
by a two-dimensionally operable switch capable of detecting operating
directions on the two dimensions such as a touch switch. The OK
button 31 is an operating member to confirm each of various items
selected using the arrow pad 30, the control dial 24, or the like.
The menu button 28 is a button for switching to a menu mode to set
various modes of this digital camera. When the menu mode is selected
at the press of this menu button 28, a menu screen appears on the
rear LCD monitor 26. The menu screen has a multi-layered structure,
so that the camera user can select any of the various items using
the arrow pad 30 and confirm the selected item by pressing the OK
button 31.
[0029]These release button 21, power switch lever 23, playback
button 27, menu button 28, arrow pad 30, and OK button 31 are linked
with ON/OFF switches, respectively. Then, signals generated in response
to actuation of the operation buttons linked with the respective
ON/OFF switches and the operating members such as the mode dial
22 and the control dial 24 are sent to a switch detection circuit
253 (see FIG. 2) inside an ASIC (Application Specific Integrated
Circuit) 262.
[0030]Referring next to FIG. 2, the general structure of the digital
camera will be described, mainly about its electric system. Inside
the lens barrel 10, lenses 101a and 101b for focus adjustment and
focal length adjustment, and an aperture 103 for adjusting the amount
of light passing therethrough are arranged. The lenses 101a, 101b
and the aperture 103 are so connected that the lenses 101a, 101b
will be driven by an optical system driving mechanism 107 and the
aperture 103 will be driven by an aperture drive mechanism 109.
The optical system driving mechanism 107 and the aperture drive
mechanism 109 are connected to a lens CPU 111, respectively, and
the lens CPU 111 is connected to the camera body 20 through the
communication contact 300. The lens CPU 111 controls the components
inside the lens barrel 10. In other words, the lens CPU 111 controls
the optical system driving mechanism 107 to perform focusing and
zoom driving, while it controls the aperture drive mechanism 109
to control the aperture value.
[0031]A movable reflecting mirror (hereinafter referred to as "movable
half mirror" for convenience) 201 having the property of transmitting
part of a light beam passing through the lenses 101a, 101b is arranged
inside a mirror box of the camera body 20.
[0032]The mirror portion of this movable half mirror is a pellicle
mirror formed by stretching and bonding to a base frame a very thin
semi-transparent film with a thickness of about 20 .mu.m, or a glass
mirror formed by depositing silver on a thin glass plate with a
thickness of 0.2 mm or less. The reason for using such a thin mirror
member as the movable half mirror is to prevent discernible ghosting,
or generation of double images, in the reflected light.
[0033]However, since this type of mirror member is very thin, there
is a danger that it could easily be damaged if the camera user touches
it with his or her finger or the like, for example, upon changing
the lens. Therefore, some contrivance is necessary to make it difficult
for the camera user to touch it upon changing the lens.
[0034]The movable half mirror 201 is rotatable about a rotation
axis 201a provided along a direction perpendicular to the paper
surface of FIG. 2, and is driven by a movable mirror driving mechanism
215 from a position inside the shooting optical path of the lens
barrel 10 to a position outside of the optical path, or vice versa.
When the movable half mirror 201 is at a position 45 degrees inclined
with respect to the optical path of the lenses 101a, 101b (as indicated
by a solid line in FIG. 2), part of the subject light beam (e.g.,
30 percent thereof) is reflected and guided to a distance measurement/light
metering sensor 217 (second light-receiving sensor) provided at
the bottom of the camera body 20, while the remaining part of the
subject light beam (70 percent) is transmitted through the movable
half mirror 201 and guided toward the CCD 221. On the other hand,
when the movable half mirror 201 is at a retracted position substantially
parallel to the optical path of the lenses 101a, 101b and hence
not to block the subject light-beam (as indicated by a chain double-dashed
line in FIG. 2), the entire subject light beam is guided to the
CCD 221.
[0035]The structure of this movable half mirror 201 will be described
later with reference to FIG. 3. In the embodiment, the rotation
center of the movable half mirror 201 is located on the lower side
of the mirror box, but the present invention is not limited to this
location. The rotation center may be located on the upper side,
or it may of course be located on either the right or left side
of the mirror box in a direction parallel to the paper surface of
FIG. 2.
[0036]The distance measurement/light metering sensor 217 is arranged
at the bottom of the mirror box in the camera body 20 and in a position
to which the light beam reflected by the movable half mirror 201
is guided. This distance measurement/light metering sensor 217 consists
of a sensor for distance measurement and a light metering sensor.
The light metering sensor includes multi-zone photometric elements
for dividing the subject image to measure the brightness of the
subject image. The distance measurement sensor is a focus detection
sensor for measuring a focusing distance using a TTL phase-difference
method. The output of the distance measurement/light metering sensor
217 is sent to a distance measurement/light-metering processing
circuit 219. The distance measurement/light-metering processing
circuit 219 outputs an evaluation metering value based on the output
of the light metering sensor, while it measures a defocus amount
of the subject image formed through the lenses 101, 101b based on
the output of the distance measurement sensor. The distance measurement
sensor and the light metering sensor can be constructed either separately
or as one unit.
[0037]A focal-plane type shutter 203 for exposure time control
and blocking light entering the CCD 221 is arranged behind the movable
half mirror 201 on the shooting optical path as the optical axis
of the lenses 101a, 101b. The driving of this shutter 203 is controlled
by a shutter drive mechanism 213. A dust-proof filter 205 is arranged
behind the shutter 203. This is a filter to prevent dust entering
from the mount opening portion of the camera body 20 or generated
inside the body from clinging to the CCD 221 or other optical elements,
casting the shadows of dust specks on images, and hence making the
images unsightly. A piezoelectric element 207 is fixed around the
entire perimeter or in a portion of the perimeter of the dust-proof
filter 205. This piezoelectric element 207 is connected to a dust-proof
filter driving circuit 211 and driven by this circuit. The piezoelectric
element 207 is driven by the dust-proof filter driving circuit 211
to vibrate the dust-proof filter 205 with a predetermined ultrasonic
wave in order to remove dust adhering to the front face of the dust-proof
filter 20S using the vibration. Note that the present invention
is not limited to the structure using the ultrasonic wave vibration
like in the embodiment as long as it can remove dust from the image
pickup device such as the CCD itself or the optical element(s) provided
in front of the image pickup device. This structure can of course
be replaced by any of various methods as appropriate, such as to
blow the dust off through a flow of air using an air pump or the
like, or to remove dust by collecting it with electrostatic action.
[0038]An infrared cut-off filter 209 is arranged behind the dust-proof
filter 205 to cut infrared light components from the subject light
beam, and an optical low-pass filter 210 for removing high frequency
components from the subject light beam is arranged behind the infrared
cut-off filter 209. Further, the CCD 221 (first light-receiving
sensor) as the image pickup device is arranged behind the optical
low-pass filter 210 to photoelectrically convert the subject image
formed through the lenses 101a, 101b into an electric signal, and
these dust-proof filter 205, infrared cut-off filter 209, optical
low-pass filter 210, and CCD 221 are housed in a package hermetically
sealed, not shown. The components are arranged to prevent dust from
entering the package. In the embodiment, the CCD is used as the
image pickup device, but the present invention is not limited to
the CCD, and any other two-dimensional image pickup device such
as a CMOS (Complementary Metal Oxide Semiconductor) can of course
be used.
[0039]The CCD 221 is connected to an image pickup device driving
circuit 223, and the driving thereof is controlled by a control
signal from an I/O circuit 239. The photoelectrically converted
analog signal output from the CCD 221 through the image pickup device
driving circuit 223 is amplified and subjected to analog-digital
conversion (AD conversion). The image pickup device driving circuit
223 is connected to an image processing circuit 227. This image
processing circuit 227 performs various image processing such as
digital amplification of digital image data (digital gain adjustment
processing), color correction, gamma (.gamma.) correction, contrast
correction, black-and-white/color mode processing, processing for
electronic finder display, etc. The image processing circuit 227
is connected to a data bus 261. Connected to this data bus 261 other
than the image processing circuit 227 are, as will be described
in detail later, a sequence controller (hereinafter referred to
as "body CPU") 229, a compression/decompression circuit
231, a video signal output circuit 233, an SDRAM control circuit
237, an I/O circuit 239, a communication circuit 241, a recording
medium control circuit 243, a flash memory control circuit 247,
and a switch detection circuit 253
[0040]The body CPU 229 connected to the data bus 261 controls the
operation of this digital camera. The compression/decompression
circuit 231 connected to the data bus 261 is a circuit for compressing
image data stored in the SDRAM 238 using JPEG or TIFF format. Note
that the image compression format is not limited to JPEG or TIFF,
and any other compression method can be employed. The video signal
output circuit 233 connected to the data bus 261 is connected to
the rear LCD monitor 26 functioning as a display device for the
electronic finder and the intra-finder LCD monitor 29 (abbreviated
as "intra-F" LCD monitor in FIG. 2) through an LCD monitor
drive circuit 235. The video signal output circuit 233 is a circuit
for converting image data, stored in the SDRAM 238 or on the recording
medium 245, into a video signal for display on the rear LCD monitor
26 and/or the intra-finder LCD monitor 29. The rear LCD monitor
26 is arranged on the backside of the camera body 20, but the location
thereof is not limited to the backside. The rear LCD monitor 26
can be arranged in any position as long as the camera user can view
it, and be of any type other than the LCD type. The intra-finder
LCD monitor 29 is arranged at a position capable of being viewed
by the camera user through the finder eyepiece part 33. Like the
rear LCD monitor 26, the intra-finder LCD monitor 29 can also be
of any type other than the LCD type. Note that it is possible to
provide only the rear LCD monitor 26 for subject image viewing without
the finder eyepiece part 33 and the intra-finder LCD monitor 29.
[0041]The SDRAM 238 is connected to the data bus 261 through the
SDRAM control circuit 237. This SDRAM 238 is a buffer memory for
temporary storage of image data processed by the image processing
circuit 227 or image data compressed by the compression/decompression
circuit 231. The I/O circuit 239 connected with the dust-proof filter
driving circuit 211, the shutter drive mechanism 213, the movable
mirror driving mechanism 215, the distance measurement/light-metering
processing circuit 219, and the image pickup device driving circuit
223 mentioned above controls input and output of data to and from
each circuit such as the body CPU 229 through the data bus 261.
The communication circuit 241 connected to the lens CPU 111 through
the communication contact 300 is connected to the data bus 261 to
communicate with the body CPU 229 and the like for exchange of data
and communication of control instructions.
[0042]The recording medium control circuit 243 connected to the
data bus 261 is connected to the recording medium 245 to control
the recording of image data and the like onto the recording medium
245. This recording medium 245 is a card type medium to be removably
loaded into the camera body 20. Alternatively, the digital camera
can be configured such that a small-size hard disk unit or a radio
communication unit is connectable to the camera body 20.
[0043]The flash memory control circuit 247 connected to the data
bus 261 is connected to a flash memory 249. This flash memory 249
stores a program for controlling the overall flow of the camera,
and the body CPU 229 controls the digital camera according to the
program stored in this flash memory. The flash memory 249 is an
electrically rewritable nonvolatile memory.
[0044]Various switches 255 include, other than a power switch 257
to be turned on/off in conjunction with the movement of the power
switch lever 23 for controlling power supply to the camera body
20 or lens barrel 10, switches for detecting first and second strokes
of the shutter release button 21, a switch linked with the playback
button 27 to instruct a playback mode, switches linked with the
arrow pad 30 used to instruct the movement of the cursor on the
screen of the rear LCD monitor 26, switches linked with the mode
dial 22 to instruct respective shooting modes, an OK switch linked
with the OK button 31 to confirm each selected mode or the like,
the mounting/demounting detection switch 259, etc. are connected
to the data bus 261 through the switch detection circuit 253. The
structure of the mounting/demounting detection switch 259 will be
described later with reference to FIG. 6.
[0045]Referring next to FIG. 3, drive means and retracting means
for the movable half mirror 201 will be described. A half mirror
401, which transmits part of a subject light beam and reflects the
remaining part of the subject light beam, is held by a mirror frame
403. This mirror frame 403 is rotatable around a shaft 411 inserted
into a through-hole 403a. In this case, the rotation axis 201a in
FIG. 2 is the central axis of the shaft 411. Both ends of an open
spring 407 are engaged between a pin 409 fixed to the camera body
20 and a drive pin 405 embedded in the mirror frame 403, respectively,
and a coil portion of this open spring 407 is wound around the shaft
411. The mirror frame 403 is urged counterclockwise (in arrow A
direction) in FIG. 3 by the spring force of this open spring 407.
The drive pin 405 is engaged with one end of a locking lever 413,
and a cam pin 415 embedded in the other end of this locking lever
413 is in engaging contact with a mirror cam 417.
[0046]The rotation center of the locking lever 413 is pivotally
supported by a mirror box, not shown, and the locking lever 413
is urged counterclockwise (in arrow B direction) in FIG. 3 by the
spring force of the open spring 407 through the drive pin 405, bringing
the cam pin 415 of the locking lever 413 into press contact with
the cam surface of the mirror cam 417. The cam surface of the mirror
cam 417 is so formed that the radial length from the rotation center
varies. In other words, it is formed such that the distance from
the rotation center will be long at a locked position 417a and shorter
at a lock-released position 417b than at the locked position 417a
on the cam surface. Further, the cam surface is formed counterclockwise
from the locked position 417a to the lock-released position 417b
with a step level difference 417c therebetween to shift smoothly
from the lock-released position 417b to the locked position 417a.
[0047]When the locked position 417a of the mirror cam 417 is in
contact with the cam pin 415, since the locking lever 413 is restricted
by the mirror cam 417 not to rotate in the arrow B direction, the
mirror frame 403 is retained in the reflecting position. Then, when
the mirror cam 417 is rotated clockwise in FIG. 3 from this position
via the step level difference 417c to a position where the lock-released
position 417b comes into contact with the cam pin 415, the locking
lever 413 becomes rotatable in the arrow B direction. This causes
the mirror frame 403 to move in the arrow A direction by the urging
force of the open spring 407 to the retracted position. The mirror
cam 417 is driven to rotate by a motor, not shown.
[0048]Since the movable half mirror 201 is thus constructed, when
the cam pin 415 is driven by a motor, not shown, to the position
where it comes into contact with the lock-released position 417b,
the mirror frame 403 and the locking lever 413 rotate in the arrow
B direction by the urging force of the open spring 407 to move the
mirror frame 403 to the retracted position indicated by a chain
double-dashed line in FIG. 3. Under this condition, when the mirror
cam 417 is rotated by the motor to the locked position 417a where
it comes into contact with the cam pin 415, the locking lever 413
is rotated clockwise (in the opposite direction of the arrow B)
to rotate the mirror frame 403 clockwise (in the opposite direction
of the arrow A) through the drive pin 405 against the urging force
of the open spring 407, thereby locating the mirror frame 403 at
the reflecting position as indicated by a solid line in FIG. 3.
[0049]It is further preferable that the above-mentioned retracted
position be so arranged that even when the lens barrel 10 is detached,
the camera user cannot touch the mirror surface directly.
[0050]FIG. 6 contains schematic views showing the mounting/demounting
detection switch 259 for detecting the mounting/demounting state
of the lens barrel 10 with respect to the camera body 20. An interlocking
pin 137 provided in the mounting part of the camera body 20 where
the lens barrel 10 is mounted is urged by a pressing spring 138
to project from the camera body 20. One end of this interlocking
pin 137 on the camera body side is in contact with a lens mounting/demounting
switch 139, and the lens mounting/demounting switch 139 is urged
by a spring into an open position. Here, reference numeral 131 denotes
a lens-side mount part of the lens barrel 10.
[0051]Since the mounting/demounting detection switch 259 is thus
constructed, when the lens barrel 10 is mounted on the camera body
20, the interlocking pin 137 is pushed in to the left by the lens-side
mount part 131 as shown in FIG. 6(A) to turn on the lens mounting/demounting
switch 139, i.e., to turn on the mounting/demounting detection switch
259. On the other hand, when the lens barrel 10 is removed from
the camera body to release the interlocking pin 137 from being pushed
in by the lens-side mount part 131 as shown in FIG. 6(B), the interlocking
pin 137 is urged by the urging force of the pressing spring 138
to project to the right in FIG. 6 to turn off the lens mounting/demounting
switch 139, i.e., to turn off the mounting/demounting detection
switch 259. Note that the detection of the mounting/demounting state
of the lens barrel 10 is not limited to use of the mechanical detection
switch as in the embodiment. For example, a photoelectric detection
switch using a photosensor can also be employed. In addition, there
are various methods such as a method using communication with the
lens CPU 111 and a method of detecting the power status of two contacts
to be connected with the lens barrel 10.
[0052]Next, the operation of the digital camera according to the
preferred embodiment of the present invention will be described
with reference to flowcharts shown in FIGS. 4 and 5. When the digital
camera enters a flow of power-on reset as shown in FIG. 4, it is
determined whether the power switch 257 of the camera body 20 is
on (S1). As a result of determination, if the power switch 257 is
off, the procedure goes to step S3 to bring the digital camera into
a sleep state (non-operating state) as a power saving state. In
this sleep state, the digital camera can return to an operating
state only when the power switch 257 shifts from off to on. When
the digital camera returns to the operating state, it performs processing
corresponding to the power switch on-state in step S5 and below.
On the other hand, if the power switch 257 is on in step S1, the
digital camera remains active (i.e., the operating state is continued),
and the state of mounting/demounting detection switch 259 is determined
in step S2 to determine whether the lens barrel 10 is detached or
not. This mounting/demounting detection switch 259 is turned off
when the lens barrel 10 is detached from the camera body 20, or
when it is not mounted properly on the camera body 20. If this switch
is off, the procedure shifts to step S51 to be described later.
On the other hand, if it is determined in step S2 that the mounting/demounting
detection switch 259 is on, the procedure goes to step S5 to perform
the processing corresponding to the power switch on-state.
[0053]In step S5, the movable half mirror 201 is moved into the
shooting optical path. When the power switch 257 is off, the movable
half mirror 201 is at the position retracted from the shooting optical
path (indicated by the chain double-dashed line in FIG. 2). Therefore,
in response to turning on the power switch 257, the movable half
mirror 201 is moved into the shooting optical path to guide the
subject light beam from the lens barrel 10 to the distance measurement/light
metering sensor 217 in order to perform light metering and distance
measurement.
[0054]Next, a dust removal operation of the dust-proof filter 205
is performed (S7). This operation is to remove dust and the like
sticking to the dust-proof filter 205 using the ultrasonic wave
as mentioned above by applying a drive voltage to the piezoelectric
element 207 from the dust-proof filter driving circuit 211.
[0055]Then, an opening operation of the shutter 203 is performed
through the shutter drive circuit 213 (S9). Thus, since the subject
light beam transmitted through the movable half mirror 201 is not
blocked by the shutter 203, a subject image is formed on the CCD
221. Then, the start of electronic finder display is instructed
so that a moving image of the subject will be displayed on the rear
LCD monitor 26 using image data captured by this CCD 221 (S11).
The operation of the electronic finder display is controlled by
the image processing circuit 227 in response to this start instruction.
[0056]Next, if there is information, such as the shooting mode
set by the mode dial 22 and the like, the ISO sensitivity, the shutter
speed and/or the aperture value manually set, etc., these shooting
conditions are read (S13). Then, the subject brightness is measured
by the distance measurement/light metering sensor 217 to calculate
the amount of exposure in order to calculate exposure control values
such as the shutter speed and the aperture value from the calculated
amount of exposure according to the shooting mode/shooting conditions
(S15). Further, the electronic finder display setting is made using
the light-metering values, the amount of exposure, and the like
(S17). In this step, in order to set the conditions of the electronic
shutter speed and the sensitivity for driving the CCD 221, calculation
and setting operations are performed based on the calculation results
of the light-metering values and the amount of exposure determined
in step S15, or using the previous displayed image, to display an
image having a proper brightness (or color value) on the rear LCD
monitor 26 and/or the intra-finder LCD 29.
[0057]Next, the procedure goes to step S19 to determine whether
the mode is the playback mode or not. This playback mode is a mode
in which, when the playback button 27 is pressed, still image data
recorded on the recording medium 245 is read and displayed on the
rear LCD monitor 26 and/or the intra-finder LCD 29. As a result
of determination, if the playback mode is set, the procedure shifts
to step S31 to instruct the image processing circuit 227 to stop
the electronic finder display. Then, after the shutter 203 is closed
(S33), the still image data recorded on the recording medium 245
is read, decompressed by the compression/decompression circuit 231,
and playback-displayed on the rear LCD monitor 26 and/or the intra-finder
LCD 29 through the video signal output circuit 233 and the LCD monitor
drive circuit 235 (S35). During playback, if any other manual operation
is performed such as the half-press of the release button 21, the
playback operation is terminated and the procedure returns to step
S7 to repeat the above-mentioned operation steps.
[0058]Returning to step S19, if the playback mode is not set, the
procedure goes to step S21 to determine whether the menu mode is
set. This is to determine whether the menu button 28 is pressed
to set the menu mode. As a result of determination, if the menu
mode is set, an instruction to stop the electronic finder display
is output in the same manner when the playback mode is set (S37),
and an instruction to close the shutter 203 is output (S39). After
that, the menu setting operation is performed (S41). In the menu
setting operation, various settings can be made, such as white balance
setting, ISO sensitivity setting, and drive mode setting. After
completion of the menu setting operation, the procedure returns
to step S7 to repeat the above-mentioned operation steps.
[0059]Returning to step S21, if the menu mode is not set as a result
of determination, the procedure goes to step S23 to determine whether
the release button 21 has been pressed halfway, i.e., whether 1R
switch is on. As a result of determination, if 1R is on, the procedure
shifts to step S43 to perform a shooting operation subroutine for
performing shooting preparation and shooting operations. The details
of this subroutine will be described later with reference to FIG.
5. After completion of the shooting operation subroutine, the procedure
returns to step S7 to repeat the above-mentioned operation steps.
[0060]Returning to step S23, if 1R switch is off as a result of
determination, the procedure goes to step S25 to determine whether
the mounting/demounting detection switch 259 is off or not like
in step S2. When the lens barrel 10 is detached, an instruction
to stop (prohibit) the electronic finder display is output like
in steps S31 and S33 in the playback mode (S45), and the shutter
203 is closed (S47). After that, the movable half mirror 201 is
retracted (S49). The retraction is accomplished, as mentioned above,
by driving the motor to rotate the mirror cam 417 and hence to rotate
the mirror frame 403 by the urging force of the open spring 407
to the position retracted from the shooting optical path (position
indicated by the chain double-dashed line in FIGS. 2 and 3).
[0061]After completion of retracting the movable half mirror 201,
or when it is determined in step S2 that the mounting/demounting
detection switch 259 is off, the procedure shifts to step S51 to
determine whether the mounting/demounting detection switch 259 is
on. This is to determine whether the lens barrel 10 is remounted
after removal of the lens barrel 10 is detected in step S25. As
a result of determination, if it is mounted, the procedure goes
to step S55 to return the movable half mirror 201. In other words,
as mentioned above, the motor is driven to rotate the mirror cam
417 and hence to rotate the locking lever 413 clockwise along the
cam surface against the urging force of the open spring 407, thereby
inserting the mirror frame 403 into the optical path of the lenses
101a, 101b. After completion of returning the movable half mirror
201, the procedure returns to step S7 to repeat the above-mentioned
operation steps.
[0062]Returning to step S51, if the mounting/demounting detection
switch 259 is off, the procedure goes to step S53 to determine whether
the power switch 257 is on. When the lens barrel 10 is removed and
the power switch 257 is on, even if any of the various operation
button is operated, the camera operation is disabled to prevent
malfunction or failure because the mount opening portion remains
open. To this end, the digital camera enters a waiting state in
which the mounting state of the lens barrel 10 and the operation
state of the power switch lever 23 are determined repeatedly in
steps S51 and S53, respectively. In step S53, if it is determined
that the power switch 257 is off, the procedure returns to step
S3 to bring the digital camera into the sleep state. Note that,
if it is determined in step S51 that the lens barrel 10 remains
detached, the procedure can omit step S53 and return to step S3
to bring the digital camera into the sleep state. Note further that
any other modifications to the procedure are possible, such as to
create a loop to go to step S9 to perform an operation based on
actuation of any of the various operation buttons.
[0063]Returning to step S25, if the mounting/demounting detection
switch 259 is on (No in step S25) as a result of determination,
i.e., when the lens barrel 10 is mounted on the camera body, the
procedure goes to step S27 to determine whether the power switch
257 is on. As a result of determination, if it is on, the procedure
returns to step S13 to repeat the above-mentioned steps. Since the
subject light beam transmitted through the movable half mirror 201
is not blocked by the shutter 203 after the electronic finder display
is started at step S11 unless any of the various operation buttons
and the like is operated step in S19 and below, the subject image
is formed on the CCD 221, and the electronic finder display is provided
to display image data captured by this CCD 221 as a moving image
on the rear LCD monitor 26 and/or the intra-finder LCD 29. On the
other hand, if it is determined in step S27 that the power switch
257 is off, the image processing circuit 227 is instructed to stop
the electronic finder display (S28) and the closing operation of
the shutter 203 is performed (S29) like in steps S31 and S33. After
that, like in the above-mentioned step S49, the movable half mirror
201 is retracted (S30), and the procedure returns to step S3 to
bring the digital camera into the sleep state.
[0064]Thus, in the embodiment, the digital camera capable of providing
the electronic finder display is configured to insert the movable
half mirror 201 into the shooting optical path upon power-on to
reflect part of the subject light beam into the distance measurement/light
metering sensor 217. This is convenient because light metering and
distance measurement can be performed immediately after power-on.
[0065]Further, in the power-on reset routine, when removal of the
lens barrel 10 is detected by the mounting/demounting detection
switch 259 (S25), the movable half mirror 201 is retracted from
the shooting optical path, while when remounting of the lens barrel
10 is detected by the mounting/demounting detection switch 259 (S51),
the movable half mirror 201 is inserted into the shooting optical
path. Therefore, when the lens barrel 10 is detached and the mount
part is open, even if the camera user or the like inserts a cleaning
tool or the like from the mount opening portion, there is no danger
that the movable half mirror 201 will be damaged or get finger marks
because the movable half mirror 201 is retracted.
[0066]Further, even when the lens barrel 10 is detached upon power-off,
since the movable half mirror 201 is retracted, there is also no
danger that the camera user or the like damages the movable half
mirror 201 or leaves finger marks thereon. Upon power-on of the
camera, since the movable half mirror 201 is inserted into the shooting
optical path, the electronic finder display operation can be performed
concurrently with the distance measurement and light metering operations.
[0067]Referring next to FIG. 5, the shooting operation subroutine
in step S43 will be described. As mentioned above, this subroutine
is performed at the half-press of the release button 21. First,
distance measurement/automatic focus adjustment is performed (S71).
Since the movable half mirror 201 is inserted into the shooting
optical path and part of the subject light beam is reflected into
the distance measurement/light metering sensor 217, the distance
measurement/light-metering processing circuit 219, the body CPU
229, and the like detect a defocus amount of the lenses 101a, 101b
by a TTL phase-difference method using this subject light beam,
and based on this detected defocus amount, the optical system driving
mechanism 107 drives the lenses 101a, 101b to a focus position through
the lens CPU 111.
[0068]Next, light metering/exposure amount calculations are made
(S73). This is also performed in such a manner that the subject
light beam reflected by the movable half mirror 201 is received
by the distance measurement/light metering sensor 217 and processed
by the distance measurement/light-metering processing circuit 219
to detect subject brightness BV. The body CPU 229 uses this subject
brightness BV to determine the amount of exposure EV and further
to determine the exposure conditions such as the shutter speed and
the aperture value according to the shooting mode and the like.
[0069]Next, it is determined whether the release button 21 is fully
pressed, i.e., whether 2R is on (S75). As a result of determination,
if it is off, the procedure goes to step S77 to determine whether
1R is on or not. If the release button 21 remains pressed halfway
after jumping to this shooting operation subroutine at the half-press
of the release button 21, the digital camera enters a waiting state
in which determinations in steps S75 and S77 are repeated. Then,
when the camera user removes his or her finger from the release
button 21 to turn 1R off, the procedure returns to step S9 in the
power-on reset routine.
[0070]Returning to step S75, if 2R switch is on as a result of
determination, i.e., when the release button 21 is fully pressed,
the procedure goes to an imaging operation for acquiring a still
image. First, in step S79, the instruction to stop the electronic
finder display is output to the image processing circuit 227. This
is to prevent disturbance of the subject light beam incident on
the CCD 221 due to the movement of the movable half mirror 201 to
the retracted position, opening/closing of the shutter 203, and
the like, upon acquiring the still image, and hence the image displayed
by the electronic finder on the rear LCD monitor 26 and/or the intra-finder
LCD 29 from becoming unsightly or visually undesirable. Then, the
movable half mirror 201 is retracted in the same manner as in step
S49 (S81).
[0071]Then, the aperture drive mechanism 109 narrows the aperture
103 through the lens CPU 111 to a set aperture value or the aperture
value calculated in S73 (S83). After completion of narrowing the
aperture, an exposure operation is performed by the CCD 221 (S85).
Since the movable half mirror 201 is at the retracted position,
the entire subject light beam that passed through the lenses 101a,
101b is focused to form the subject image on the CCD 221. Under
this condition, resetting of the electronic shutter of the CCD 221
is released to start accumulation of electric charges of photoelectric
conversion current representing the subject image. Then, when the
exposure time manually preset or set in step S73 has elapsed, the
electronic shutter of the CCD 221 stops accumulation of the electric
charges of the photoelectric conversion signal. In the exposure
operation of step S85, the exposure time is controlled by the electronic
shutter of the CCD 221, but the present invention is not limited
thereto, and the exposure time can also be controlled by the shutter
203. In this case, front and rear curtains of the shutter 203 needs
moving to their initial positions before the start of the exposure
operation.
[0072]Then, the shutter 203 is closed (S87), and an instruction
to open the aperture 103 to the maximum is output to the lens CPU
111 (S89). Further, the image signal acquired by the CCD 221 accumulating
the electric charges is read out (S91), and subjected to image processing
through the image processing circuit 227 and the like (S93). Then,
after signal compression or the like is performed through the compression/decompression
circuit 231, resulting image data is recorded on the recording medium
245 (S95). After completion of recording the image data, it is determined
in step S97 whether 1R switch is on, i.e., whether the release button
21 remains pressed halfway (S97). When 1R switch is turned off,
the procedure goes to step S99 to return the movable half mirror
201 in the same manner as in step S55. After completion of returning
the movable half mirror 201, the procedure returns to the power-on
reset routine.
[0073]In the shooting operation subroutine of the embodiment, the
movable half mirror 201 is retracted during the imaging operation
for acquiring the still image. This can avoid reducing the amount
of light transmitted through the movable half mirror 201, and hence
increase the amount of subject light upon acquiring the still image,
enabling shooting at a faster shutter speed. Further, after completion
of the imaging operation, the movable half mirror 201 is returned
in step S99. Therefore, when the release button 21 is pressed halfway
again after shooting, light metering and distance measurement can
be performed immediately and concurrently with the electronic finder
display.
[0074]In the embodiment, the operating and non-operating states
of the camera are switched by the power switch 257. However, in
addition to the switching operation of this power switch 257, determination
means may be provided as an alternative example to determine whether
the camera has been operated or not for a predetermined period of
time. In this case, when the camera has not been operated for the
predetermined period of time, the determination means determines
that the camera is in the non-operating state to start retracting
the movable half mirror 201. Specifically, a timer to be reset in
response to actuation of any of the various operating members and
operation buttons, such as the release button 21, the mode dial
22, the control dial 24, the playback button 27, the menu button
28, the arrow pad 30, and the OK button, is provided so that the
movable half mirror will be retracted in step S29 at the time when
the predetermined period of time counted by this timer has elapsed.
[0075]As described above, according to the embodiment, the digital
camera capable of providing the electronic finder display is configured
to insert the movable half mirror 201 into the shooting optical
path upon activation of the camera to reflect part of the subject
light beam into the distance measurement/light metering sensor 217.
This is convenient because light metering and distance measurement
can be performed concurrently with the electronic finder display
immediately after the release button 21 is pressed halfway to turn
1R on during the electronic finder display.
[0076]Further, in the embodiment, the power-on and the power-off
can be set by the power switch 257, and the movable half mirror
201 is made movable between the position inserted in the shooting
optical path and the position retracted from the shooting optical
path in such a manner to move the movable half mirror 201 to the
retracted position upon power-on. Therefore, even if a cleaning
tool or the like is inserted from the mount opening portion of the
camera body during power-off, there is no danger of damaging the
movable half mirror 201. On the other hand, the movable half mirror
201 is moved from the position retracted from the shooting optical
path to the position inserted into the shooting optical path-upon
power on, so that light metering and distance measurement can be
performed immediately. The non-operating state of the camera includes,
but not limited to, turning off the power switch. As mentioned above,
the non-operating state is also determined when the camera has not
been operated for a predetermined period of time.
[0077]Further, in the embodiment, the movable half mirror 201 is
moved to the position retracted from the shooting optical path when
the lens barrel 10 is removed. Therefore, even if a cleaning tool
or the like is inserted from the mount opening portion of the camera
body, there is no danger of damaging the movable half mirror 201.
Then, when the lens barrel 10 is remounted on the camera body, the
movable half mirror 201 is inserted into the shooting optical path.
This enables distance measurement and light metering to be performed
concurrently with the electronic finder display. In the embodiment,
the CCD 221 as the image pickup device receives light transmitted
through the movable half mirror 201 and the distance measurement/light
metering sensor 217 receives light reflected by the movable half
mirror 201. Conversely, the digital camera can be configured such
that the CCD 221 receives reflected light and the distance measurement/light
metering sensor 217 receives transmitted light. Further, in the
embodiment, the sleep state as the power saving state is described
as an example of the non-operatinq state, but the non-operating
state also includes the power-off state in which the camera consumes
no power at all.
[0078]In the embodiment, although the lens barrel 10 is described
as an example of the part to be mounted on the opening portion of
the camera body 20 of the present invention, it is not limited to
the lens barrel 10. For example, various other devices or accessories
such as a bellows and an extension tube can be considered to be
mounted. Further, the present invention is of course applicable
to cameras designed specifically to be attached to various other
equipment, such as microscopes, binoculars, etc. Thus, the present
invention is also applicable to those other than general-purpose
digital cameras as long as they have an opening portion through
which the half mirror is likely to be exposed to the outside.
[0079]While there has been shown and described what is considered
to be a preferred embodiment of the invention, it will, of course,
be understood that various modifications and changes in form or
detail could readily be made without departing from the spirit of
the invention. It is therefore intended that the invention not be
limited to the exact form described and illustrated, but constructed
to cover all modifications that may fall within the scope of the
appended claims. |