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Digital Camera Patent Abstract
A digital camera is constituted of a camera body and a lens unit.
The lens unit is removably attached to the camera body. When the
lens unit is attached to the camera body, they are electrically
connected through connection terminals. A nonvolatile memory in
the lens unit previously stores a chart image that is obtained by
capturing a resolving power chart representing image resolving power
by a CCD. When an attachment detector of the camera body detects
that the lens unit is attached to the camera body, the chart image
is transferred into the camera body and is displayed on a LCD.
Digital Camera Patent Claims
1. A digital camera constituted of a lens unit having a taking lens
and an imaging device incorporated therein, and a camera body to
which said lens unit is removably attached, said digital camera
comprising: electrical connectors for electrically connecting said
lens unit and said camera body when said lens unit is attached to
said camera body; a nonvolatile memory provided in said lens unit,
for previously storing characteristics information related to characteristics
of said lens unit; an attachment detector provided in said camera
body, for detecting that said lens unit is attached to said camera
body; a controller provided in said camera body, for transferring
said characteristics information from said nonvolatile memory through
said electrical connectors into said camera body when said attachment
detector detects that said lens unit is attached to said camera
body; a signal processor provided in said camera body, for processing
said characteristics information; and a display provided in said
camera body, for displaying an information image based on said characteristics
information that is processed in said signal processor.
2. A digital camera as claimed in claim 1, wherein said characteristics
information is resolving power chart information, said resolving
power chart representing image resolving power.
3. A digital camera as claimed in claim 2, wherein said resolving
power chart information is a chart image that is captured by said
imaging device at manufacture of said lens unit, said chart image
being displayed as said information image on said display when said
lens unit is attached to said camera body.
4. A digital camera as claimed in claim 1, wherein said taking
lens is a zoom lens, said characteristics information being information
about focal distance that is variable through said zoom lens and
a chart image, said chart image being electronically varied to a
size based on said focal distance information and being displayed
as said information image on said display when said lens unit is
attached to said camera body.
5. A digital camera as claimed in claim 4, wherein said chart image
is captured by said imaging device at manufacture of said lens unit
and stored in said nonvolatile memory.
6. A digital camera constituted of a lens unit having at least
an imaging device incorporated therein, and a camera body to which
said lens unit is removably attached, said digital camera comprising:
electrical connectors for electrically connecting said lens unit
and said camera body when said lens unit is attached to said camera
body; an attachment detector provided in said camera body, for detecting
that said lens unit is attached to said camera body; a light-shielding
member located in front of said imaging device, for moving between
a close position for shielding said imaging device from light and
an open position for retracting from said imaging device; a nonvolatile
memory provided in said lens unit, for previously storing a light-shielded
image or a chart image as a standard image; a controller provided
in said camera body, for transferring a present light-shielded image
and said standard image that is stored in said nonvolatile memory
into said camera body through said electrical connectors when said
attachment detector detects that said lens unit is attached to said
camera body, said present light-shielded image being captured by
said imaging device with said light-shielding member being set in
said close position; a deterioration judgment unit provided in said
camera body, for judging deterioration level of said imaging device
by comparing said standard image and said present light-shielded
image; and an alarm unit provided in said camera body, for alarming
when said deterioration level of said imaging device is judged to
be equal to or higher than a predetermined value.
7. A lens unit having a taking lens and an imaging device incorporated
therein, and removably attached to a camera body, said lens unit
comprising: a nonvolatile memory for previously storing characteristics
information related to characteristics of said lens unit, said characteristics
information being transferred into said camera body.
8. A lens unit as claimed in claim 7, wherein said characteristics
information is an image of a resolving power chart captured by said
imaging device.
9. A lens unit as claimed in claim 7, further comprising: a zoom
lens as said taking lens; and a moving mechanism that moves said
zoom lens for zooming, wherein said characteristics information
being information about said zoom lens's focal distance that is
variable through said moving mechanism and a chart image that is
captured by said imaging device.
10. A lens unit having an imaging device incorporated therein,
and removbably attached to a camera body, said lens unit comprising:
a light-shielding member located in front of said imaging device,
for moving between a close position for shielding said imaging device
from light and an open position for retracting from said imaging
device; and a nonvolatile memory for storing either a light-shielded
image or a chart image, as a standard image, said light-shielded
image being captured by said imaging device at manufacture of said
lens unit with said shielding member being set in said lose position,
said standard image being transferred into said camera body when
said lens unit is attached to said camera body.
11. A method of identifying characteristics of a lens unit, said
lens unit having a taking lens and an imaging device incorporated
therein, and removably attached to a camera body, said method comprising
the steps of: detecting that said lens unit is attached to said
camera body; transferring characteristics information related to
characteristics of said lens unit that is stored in a nonvolatile
memory of said lens unit into said camera body, and displaying an
information image based on said characteristics information on a
display provided in said camera body.
12. A method of identifying characteristics of a lens unit as claimed
in claim 11, wherein said characteristics information is a chart
image that is obtained by capturing a resolving power chart representing
image resolving power by said imaging device at manufacture of said
lens unit, said chart image being displayed as said information
image on said display when said lens unit is attached to said camera
body.
13. A method of identifying characteristics of a lens unit as claimed
in claim 11, wherein said characteristics information is information
about said tanking lens's focal distance at the time of zooming
of said lens unit and a chart image captured by said imaging device,
said chart image being electronically varied to a size based on
said focal distance information and being displayed as said information
image on said display when said lens unit is attached to said camera
body.
14. A method of judging deterioration of a lens unit, said lens
unit comprising an imaging device and a light-shielding member that
is located in front of said imaging device and moves between a close
position for shielding said imaging device from light and an open
position for retracting from said imaging device, said lens unit
being removably attached to a camera body, said method comprising
the steps of: detecting that said lens unit is attached to said
camera body; capturing a present light-shielded image by said imaging
device with said light-shielding member being set in said close
position; judging deterioration level of said imaging device by
comparing a standard image from a nonvolatile memory of said lens
unit and said present light-shielded image, said standard image
being either a light-shielded image that is captured by said imaging
device at manufacture of said lens unit or a chart image; and alarming
when said deterioration level of said imaging device is judged to
be equal to or higher than a predetermined value.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a lens-interchangeable
digital camera and a lens unit, a method of identifying characteristics
of the lens unit and a method of judging deterioration of the lens
unit.
[0003] 2. Description of the Related Arts
[0004] Recently, there is a widespread use of digital cameras that
record digital image data in a recording medium such as a built-in
memory or a memory card. In such digital cameras, an image captured
by an imaging device such as a CCD is converted into the digital
image data. There are two types of the digital camera: one is an
all-in-one type in which a taking lens is integrated with a camera
body, and the other is a lens-interchangeable type in which one
of various taking lenses is removably attached to the camera body.
[0005] Many of the lens-interchangeable cameras adopt existing
systems for traditional silver halide cameras (see Japanese Patent
Laid-Open Publication No. 8-171130). That is, they generally utilize
interchangeable lenses for the silver halide cameras with little
modification, and have a configuration in which a subject image
is focused on an imaging device incorporated in a camera body, instead
of using a silver halide photographic film, and image data is recorded
in a recording medium.
[0006] However, since the imaging device becomes small and its
resolving power is improved these days, a digital camera having
a new system is considered rather than using the existing systems
of the silver halide cameras. For example, a digital camera disclosed
in Japanese Patent Laid-Open Publication No. 11-346325 has not only
an interchangeable lens but also an interchangeable imaging module
with imaging devices arranged therein.
[0007] As another new system for the lens-interchangeable digital
cameras, it is considered that the imaging device is incorporated
in the interchangeable lens. For this configuration, it is only
necessary to connect the interchangeable lens to the camera body
electrically without connecting them optically. Therefore, the structure
can be relatively simplified.
[0008] In the lens-interchangeable digital camera, however, it
is necessary to check captured images by doing a test shoot after
the interchangeable lens is attached to the camera body, in order
to obtain characteristics of each lens. Accordingly, it has been
a problem that a user cannot know what kind of images can be obtained
with the interchangeable lens, which is going to be used. Moreover,
in the system in which the imaging device is incorporated in the
interchangeable lens, the characteristics including resolving power
of the imaging device, a range of zoom magnification and a field
angle in macro capturing are different from each interchangeable
lens. However, there has been no device that facilitates instant
identification of these characteristics. In the digital camera described
in the Japanese Patent Laid-Open Publication No. 11-346325, when
the imaging module is exchanged, information relating to the imaging
devices, a control program, and the like are sent to the camera
body. However, the characteristics of the lens cannot be identified.
[0009] In addition, in the conventional lens-interchangeable digital
camera, it is difficult to confirm performance deterioration of
the imaging device even when quality of the captured image is degraded
due to the performance deterioration of the imaging device with
time.
SUMMARY OF THE INVENTION
[0010] An object of the present invention is to provide a digital
camera and a lens unit capable of informing a user of characteristics
of an interchangeable lens and performance deterioration of an imaging
device when the interchangeable lens is attached to a camera body,
and a method of identifying characteristics of the lens unit and
a method of judging deterioration of the lens unit.
[0011] In order to achieve the above and other objects, a digital
camera of the present invention includes electrical connectors,
an attachment detector, a nonvolatile memory, a controller, a signal
processor and a display. The nonvolatile memory is provided in a
lens unit, whereas the attachment detector, the controller, the
signal processor and the display are provided in a camera body.
The electrical connectors electrically connect the lens unit and
the camera body. The attachment detector detects that the lens unit
is attached to the camera body. The nonvolatile memory stores characteristics
information related to characteristics of the lens unit. When the
lens unit is attached to the camera body, the characteristics information
is readout from the nonvolatile memory, and is processed in the
signal processor to be displayed as an information image on the
display.
[0012] In a preferable embodiment of the present invention, the
characteristics information is a chart image. This chart image is
obtained by capturing a resolving power chart representing image
resolving power by the imaging device at the time of manufacturing
the lens unit, and is stored in the nonvolatile memory. When the
lens unit is attached to the camera body, the chart image is read
out from the nonvolatile memory and is displayed on the display.
[0013] In another preferable embodiment of the present invention,
the lens unit includes a zoom lens and a moving mechanism that moves
the zoom lens for zooming. The characteristics information includes
information about the zoom lens's focal distance, and a chart image.
When the lens unit is attached to the camera body, the chart image
is electronically varied to a size based on the information about
the focal distance and is displayed on the display.
[0014] In the other preferable embodiment of the present invention,
the lens unit includes a light-shielding member, a deterioration
judgment unit and an alarm unit. The deterioration judgment unit
and the alarm unit are provided in the camera body. The light-shielding
member moves between a close position for shielding the image device
from light and an open position for retracting from the imaging
device. The nonvolatile memory stores either a light-shielded image
or a chart image, as a standard image. The light-shielded image
is captured by the imaging device at manufacture of the lens unit
while the shielding member is set in the close position. When the
attachment detector detects that the lens unit is attached to the
camera body, the light-shielding member is set in the close position
by the controller, and a present light-shielded image is captured
by the imaging device. Deterioration level of the imaging device
is judged by comparing the present light-shielded image and the
standard image. When the deterioration level of the imaging device
is equal to or higher than a predetermined value, the alarm unit
alarms accordingly.
[0015] A method of identifying characteristics of a lens unit according
to the present invention includes the steps of detecting that a
lens unit is attached to a camera body; transferring characteristics
information stored in a nonvolatile memory into the camera body;
and displaying an information image based on the characteristics
information on a display.
[0016] A method of judging deterioration of a lens unit according
to the present invention includes the steps of transferring a present
light-shielded image, which is captured by an imaging device while
a light-shielding member is set in a close position, into a camera
body; transferring a standard image, which is either a light-shielded
image at manufacture or a chart image, from a nonvolatile memory
into the camera body; judging deterioration level of the imaging
device by comparing the present light -shielded image and the standard
image; and alarming when the deterioration level of the imaging
device is judged to be equal to or higher than a predetermined value.
[0017] According to the present invention, when the lens unit is
attached to the camera body, the characteristics information of
the lens unit is transferred from the nonvolatile memory into the
camera body, and the information image based on the characteristics
information is displayed on the display. Owing to this, the characteristics
of the lens unit can be identified from this information image,
before capturing images.
[0018] According to the present invention, when the lens unit is
attached to the camera body, the chart image that is the resolving
power chart captured by the imaging device is displayed on the display.
Owing to this, the resolving power of the lens unit can be immediately
identified.
[0019] According to the present invention, when the lens unit is
attached to the camera body, the chart image that is electronically
varied to the size based on the information about the focal distance
is displayed as the information image on the display. Owing to this,
zoom magnification of the lens unit can be immediately identified.
[0020] According to the present invention, the deterioration level
of the imaging device is judged by comparing the standard image
readout from the nonvolatile memory and the present light-shielded
image. Owing to this, the deterioration level of the imaging device
can be easily identified when the lens unit is attached to the camera
body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The above and other subjects and advantages of the present
invention will become apparent from the following detailed description
of the preferred embodiments when read in association with the accompanying
drawings, which are given by way of illustration only and thus are
not limiting the present invention. In the drawings, like reference
numerals designate like or corresponding parts throughout the several
views, and wherein:
[0022] FIG. 1 is a perspective view of a digital camera to which
a lens unit is attached;
[0023] FIG. 2 is a perspective view of the digital camera from
which the lens unit is removed;
[0024] FIG. 3 is a rear view of the digital camera;
[0025] FIG. 4 is a block diagram illustrating an electrical structure
of the digital camera;
[0026] FIG. 5 is an explanatory view illustrating a resolving power
chart;
[0027] FIG. 6 is a flow chart for displaying information about
resolving power;
[0028] FIG. 7 is an explanatory view illustrating a chart showing
information about zoom magnification;
[0029] FIG. 8 is a flow chart for displaying the information about
the zoom magnification;
[0030] FIG. 9 is a block diagram illustrating an electrical structure
of the digital camera in a different embodiment;
[0031] FIG. 10 is an explanatory view illustrating a light-shielded
image; and
[0032] FIG. 11 is a flow chart for judging deterioration level
of a CCD.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] As shown in FIGS. 1 and 2, a digital camera 2 is constituted
of a camera body 3 and a lens unit 4, which is removably attached
to the camera body 3. When the lens unit 4 is attached to the camera
body 3, they are connected electrically.
[0034] A lens side mount portion 5 provided on a rear surface of
the lens unit 4 is formed with bayonet claws 6. One of the bayonet
claws 6 is provided with a connection terminal 6a. A body side mount
portion 7 provided on a front surface of the camera body 3 is formed
with a bayonet gap 8. When the lens unit 4 is attached to the camera
body 3, the bayonet claws 6 are forced into the bayonet gap 8. The
lens unit 4 is then rotated so as to engage the bayonet claws 6
and bayonet claws 8a. When the lens unit 4 is rotated by a predetermined
angle, a lock pin 9 of the mount portion 7 is engaged with a pin
hole (not shown) of the mount portion 5, thereby positioning the
lens unit 4. The connection terminal 6a is connected to a connection
terminal 7a (see FIG.4) of the mount portion 7 when the lens unit
4 is positioned. A mount lid 11 biased forward by a spring is provided
in the mount portion 7 to prevent dust from entering into the camera
body 3 when the lens unit 4 is removed.
[0035] The body side mount portion 7 is provided with a lock release
button 10, which is operated in cooperation with the lock pin 9.
The lock release button 10 is operated to remove the lens unit 4.
When the rock release button 10 is pressed, the lock pin 9 is moved
backward, thereby releasing the lock.
[0036] A release button 12 that is pressed for capturing images
and a mode operating dial 13 that is operated for switching between
a capture mode and a reproduction mode are provided on a top surface
of the camera body 3. As shown in FIG. 3, an LCD 15 on which the
captured image and various setting conditions are displayed, a power
switch 16, and a zoom operating section 17 are provided on a rear
surface of the camera body 3.
[0037] Referring back to the FIG. 2, A CCD (imaging device) 21,
a taking lens 22, a nonvolatile memory 23 and so forth are provided
in a cylindrical unit body 20.
[0038] In FIG.4, the taking lens 22 is constituted of lens groups
26, 27, and 28. The lens groups 27, 28 respectively function as
a zoom lens and a focus lens, and are respectively moved by a zoom
lens motor 31 and a focus lens motor 32. The CCD 21 is arranged
behind the lens group 28. A shutter mechanism 30, an aperture stop
mechanism (not shown) and so forth are arranged in front of the
CCD 21. The shutter mechanism 30 is controlled by a shutter driver
39, and is varied between a close position for shielding the CCD
21 from light and an open position for retracting from the CCD 21.
[0039] The zoom lens motor 31 is connected to a zoom motor driver
40, and is controlled by a system controller 41 for the lens unit
(hereinafter system controller 41) through the zoom motor driver
40. The focus lens motor 32 is connected to a focus motor driver
42, and is controlled by the system controller 41 through the focus
motor driver 42.
[0040] The CCD 21 is connected to a CCD driver 43, and is controlled
by the system controller 41 through the CCD driver 43. The CCD 21
converts an optical subject image into an electrical image signal
to output. After being amplified to proper level by an amplifier
44, the image signal is digitally converted by an A/D converter
45 to image data. The image data is sent to the camera body 3 through
a serial driver 46. The system controller 41 controls capturing
processing of the lens unit 4 based on instructions from a system
controller 55 for the camera body (hereinafter system controller
55).
[0041] The image data from the lens unit 4 is written in a memory
48 through a serial driver 47. A signal processor 49 reads out the
image data from the memory 48 and applies various kinds of image
processing including gradation conversion, white balance correction
and .gamma.-correction to the image data. The image data to which
the image processing is applied is input in an LCD driver 50 to
be displayed on the LCD 15 as a through image. When the mode operating
dial 13 is operated to select the reproduction mode, the image recorded
in a recording media 53 or setting conditions for image capturing
is displayed on the LCD 15.
[0042] When the release button 12 is pressed, the image data to
which the image processing has been applied is recorded in the recording
media 53 by the media controller 52. At the same time, a flash unit
14 is driven in accordance with brightness of the subject. The system
controller 55 sends the instructions to the system controller 41,
and also controls the camera body for the capturing processing,
image displaying processing, recording processing, and so forth.
The release button 12, the mode operating dial 13, the power switch
16, and the zoom operating section 17 are connected to the system
controller 41. When the zoom operating section 17 is operated, the
zoom lens group 28 is moved forward and backward to perform zooming.
[0043] A main battery 56 is provided in the camera body 3 to supply
electric power to each section of the camera body 3. The lens unit
4 is provided with a sub-battery 57. The main battery 56 and the
sub-battery 57 are connected with each other through the connection
terminals 6a, 7a of the mount portions 5, 7. The electric power
is supplied from the main battery 56 to the sub-battery 57, and
then is supplied from the sub-battery 57 to each section of the
lens unit 4.
[0044] An attachment detector 58 for detecting the attachment of
the lens unit 4 is provided in the camera body 3. When the attachment
detector 58 is electrically connected to the lens unit 4 through
the connection terminals 6a, 7a, it detects electrical potentials
of the connection terminal 6a. The attachment detector 58 then sends
information that the lens unit 4 is attached to the camera body
3 to the system controller 41.
[0045] The nonvolatile memory 23 provided in the lens unit 4 previously
stores a chart image. The chart image of the present embodiment
is an image obtained by capturing, for instance, a resolving power
chart 60 as shown in FIG.5 by the CCD 21, and it represents image
resolving power of the lens unit 4. The resolving power chart 60
is called a wedge chart. In the wedge chart 61, five black belts
and four white belts respectively having the identical width are
arranged alternately in a lateral (horizontal) direction. Below
the wedge chart 61, a scale 62 is arranged. When the image of the
resolving power chart 60 is checked, it is possible to observe a
limit line at which the black and white belts are accurately resolved.
That it, a numeric value of the resolving power shown by the limit
line can be read by the scale 62. When the numeric value of the
scale 62 is high, the resolving power of the CCD 21 is also high.
As the chart image, an image of a general landscape or a chart image
in conformity with the ISO (International Organization for Standardization)
standards and the standard of the Institute of Image Electronics
Engineers of Japan may be used.
[0046] Next, the operation according to the first embodiment is
explained with referring to FIG. 6. When the lens unit 4 is attached
to the camera body 3, they are electrically connected to each other.
When the power switch 16 of the camera body 3 is turned on, the
attachment detector 58 detects whether the lens unit 4 is attached.
When the attachment detector 58 detects that the lens unit 4 is
attached to the camera body 3, the system controller 55 reads out
the chart image from the nonvolatile memory 23 of the lens unit
4 through the system controller 41 to perform signal processing
in the signal processor 49. Then, the LCD 15 is activated, and the
chart image is displayed thereon. A user can identify the resolving
power as the characteristics of the lens unit 4 by observing the
chart image on the LCD 15. In this way, the user can know the characteristics
of the lens unit 4 by identifying types of the lens unit 4 before
capturing images, therefore the user can predict the image to be
obtained by the lens unit 4, which is going to be used.
[0047] According to the present invention, it is also possible
that the digital camera 2 notifies the zoom magnification that is
the characteristics of the lens unit 4 before capturing images.
In the second embodiment of the present invention, the nonvolatile
memory 23 previously stores respective focal distance information
about the taking lens 22 moved to a telephoto side and to a wide
side at the time of zooming with the lens unit 4, and a chart image
captured by the CCD 21. The chart image of the present embodiment
is an image obtained by capturing, for instance, a chart 78 as shown
in FIG. 7 by the CCD 21. In the chart 78, a scale 79 having numbered
longitudinal and lateral axes 79a, 79b is arranged with its origin
located at the center of a screen. As the stored focal distance
information, for example, the numeric value of the wide side is
34 mm, while that of the telephoto side is 102 mm.
[0048] Next, the operation according to the second embodiment is
explained with referring to FIG. 8. When the lens unit 4 is attached
to the camera body 2, the system controller 55 reads out the chart
image and the focal distance information of the taking lens 22 from
the nonvolatile memory 23 of the lens unit 4 through the system
controller 41 to perform signal processing in the signal processor
49. Then, the chart image is electronically varied to a size based
on the focal distance information to be displayed on the LCD 15.
That is, the chart image in which the lens unit 4 is moved to the
telephoto side is displayed on the LCD 15 in accordance with the
focal distance information of the taking lens 22 at the telephoto
side and the image signal of the chart image. The chart image displayed
on the LCD 15 is, for example, a range surrounded by a dashed line
in FIG. 7 including the largest numeric value "5". Then,
the chart image in which the lens unit 4 is moved to the wide side
is displayed on the LCD 15 in accordance with the focal information
of the taking lens 22 at the wide side and the image signal of the
chart image. At this time, the chart image displayed on the LCD
15 is, for example, a range surrounded by a chain-double dashed
line in FIG. 7. This chart image contains only a part of the original
chart image cropped through an electrical zoom processing, and includes
the numeric value "3" and less. The user can identify
the variable range of the magnification in zooming with the lens
unit 4 by observing the chart image on the LCD 15. Thus the user
can know the characteristics including the zoom magnification of
the lens unit 4 before capturing images. After checking the chart
image, the mode operating dial 13 is operated to switch the mode
to the capture mode or the reproduction mode.
[0049] Although the second embodiment uses the lens unit having
the zooming function and the zoom magnification is informed to the
user, it is also possible to use a lens unit having a macro-function.
In this case, each focal distance information of normal capturing
and macro capturing, and the chart image are previously stored in
the nonvolatile memory. The image signals of the focal distance
information and the chart image are processed in the signal processor
49, and the chart images in the normal capturing and in the macro
capturing are displayed on the LCD 15 sequentially.
[0050] In the first and second embodiments, the user is informed
of the characteristics information about the lens unit stored in
the nonvolatile memory when the lens unit is attached to the camera
body, so that they can identify the types of the lens unit. Meanwhile,
in a third embodiment descried later, performance deterioration
of the CCD with time is detected when the lens unit is attached
to the camera body so as to inform the user accordingly. In FIG.
9, a camera body 80 is constituted of a camera body 81 and a lens
unit 82. In FIG. 10, the components identical to those in the first
embodiment shown in FIG. 4 are represented by same numerals, and
explanations of them are omitted.
[0051] A light-shielded image 84 as shown in FIG. 10 is previously
stored as a standard image in a nonvolatile memory 83 provided in
the lens unit 82. Since the light-shielded image 84 is captured
by the CCD 21 by actuating the shutter mechanism to the close position
at the time of manufacturing the lens unit 82, the entire image
appears almost black. White portions 87 are flaws on the CCD. The
camera body 81 is provided with a deterioration judgment unit 85
for judging the deterioration level of the CCD 21, and an alarm
unit 86 for alarming when the deterioration judgment unit 85 judges
that the deterioration level of the CCD 21 is equal to or higher
than a predetermined value.
[0052] Next, the operation according to the third embodiment is
explained with referring to FIG. 11. When the lens unit 82 is attached
to the camera body 81, they are electrically connected to each other.
When the power switch 16 of the camera body 81 is turned on, the
attachment detector 58 detects whether the lens unit 82 is attached.
When the attachment of the lens unit 82 is detected, the system
controller 55 activates the system controller 41 in the lens unit
82, and controls the shutter driver 39 to actuate the shutter mechanism
30 to the close position. In the close position state, a present
light-shielded image is captured by the CCD 21. The image signal
of the present light-shielded image, which is captured at the time
of the attachment of the lens unit 82, is sent to the signal processor
49 to be processed. The system controller 55 retrieves the image
signal of the light-shielded image 84 at manufacture from the nonvolatile
memory 83 to apply the signal processing thereto in the signal processor
49. The light-shielded images at manufacture and present, which
are transferred into the system controller 55, are sent to the deterioration
judgment unit 85. The deterioration judgment unit 85 judges the
deterioration level of the CCD 21 by comparing light-shielded images
at manufacture and present. For instance, the light-shielded images
at manufacture and present are respectively converted into an image
binarized into white and black, and compared with each other. Thereby,
the flaws on the CCD 21 are represented as the white portions 87,
while the other portion is represented in black, as shown in FIG.
10. When area ratio of the white portions increased in the present
light-shielded image as compared to the light-shielded image 84
at manufacture exceeds a predetermined threshold value, the deterioration
judgment unit 85 judges that the CCD 21 is deteriorated, and sends
a judgment result to the alarm unit 86. Based on the judgment result,
the alarm unit 86 reads out an alarm image showing the deterioration
of the CCD 21 from the memory 48 to display it on the LCD 15.
[0053] In the third embodiment, although the deterioration level
of the CCD is judged according to the dimension of the white portions
87, it is also possible to judge the deterioration level according
to a degree of shading or color shading (color unevenness). In this
case, as well as the third embodiment, light-shielded images at
manufacture and present are compared. When the degree of the shading,
which is a decrease of light amount around the perimeter of a screen
as compared to the center thereof, is compared, a brightness ratio
of the perimeter of the screen to that of the center of the screen
is calculated in both of the light-shielded images at manufacture
and present. When the brightness ratio of the present light-shielded
image has decreased from that of the light-shielded image at manufacture
to the extent of, for example, more than a predetermined threshold
value, the CCD is judged to be deteriorated. When the degree of
the color shading, which is a change in color tone around the perimeter
of the screen as compared to the center thereof, is compared to
judge the deterioration of the CCD, a color tone ratio of the perimeter
of the screen to that of the center of the screen in each R, G and
B is calculated in both of the light-shielded images at manufacture
and present. When the color tone ratio of the present light-shielded
image has changed from that of the light-shielded image at manufacture
to the extent of, for example, more than a predetermined threshold
value, the CCD is judged to be deteriorated.
[0054] In the third embodiment, although the light-shielded image
at manufacture is previously captured and stored in the nonvolatile
memory 83, it is also possible to store an image in which the entire
screen is dark (the brightness is low) in the nonvolatile memory
as the chart image. In this case, the chart is formed on a rear
surface of the shutter or the light-shielding member. Additionally,
although the alarm image is displayed on the LCD in the third embodiment,
it is also possible to make sound for alarming or to make an LED
emit light for alarming.
[0055] Moreover, in the third embodiment, although the shutter
mechanism shields the CCD from light to obtain the light-shielded
image, it is also possible to provide a light-shielding mechanism
for capturing the light-shielded image.
[0056] In the above embodiments, the lens-interchangeable digital
camera in which the lens unit is removably attached to the camera
body is used. However, the present invention can also be applied
to a digital camera with an interchangeable imaging module composed
of a CCD (imaging device) and a driving circuit for the CCD. Moreover,
the present invention can be also applied to various types of cameras
like a video camera, besides the digital camera. Furthermore, it
is possible that the lens unit and the camera body are configured
to communicate image signals by radio.
[0057] Although the present invention has been fully described
by the way of the preferred embodiments thereof with reference to
the accompanying drawings, various changes and modifications will
be apparent to those having skill in this field. Therefore, unless
otherwise these changes and modifications depart from the scope
of the present invention, they should be construed as included therein.
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