JP2007013867A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital camera removing dust by operating a dust-proof filter only when the dust is stuck on the dust-proof filter, even without causing a photographer to especially care about dust. <P>SOLUTION: An image acquired by an imaging element 61 for display is resized so as to match an image acquired by an imaging element 68 for recording and in the state of normalizing white balances of both the images, an image for finder acquired by the imaging element 61 for display is compared with an image for recording acquired by the imaging element 68 for recording. As a result of the comparison, if it is detected that dust is stuck on a dust-proof filter 67, the dust-proof filter 67 is vibrated to remove dust. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a digital camera, and more particularly to a lens interchangeable single-lens reflex type digital camera.

  In a single-lens reflex digital camera with an interchangeable lens, dust may enter from the outside and adhere to the image sensor during lens replacement. As a countermeasure against such dust, for example, in Patent Document 1, a dust-proof filter is incorporated in the front surface of the image sensor to prevent dust from entering the image sensor, and dust attached to the dust-proof filter is passed through the dust-proof filter. Techniques have been proposed for removal by sonic vibration.

In addition, many single-lens reflex digital cameras cannot display an image on a liquid crystal display device when framing is performed using an optical finder. As a countermeasure, for example, in Patent Document 2, a finder optical path is divided, and an image sensor for imaging other than that for imaging is arranged on the divided finder optical path, thereby capturing an image for framing different from that for imaging. A technique for displaying an image obtained by imaging on a liquid crystal display device has been proposed.
JP 2003-319222 A JP 2000-165730 A

  In the method of the above-mentioned Patent Document 1, the dust attached after the dustproof filter is actuated is operated again by the photographer who confirms the image obtained after the imaging is finished, or the dustproof filter is actuated for every imaging. Need to be removed. Here, if the photographer operates the dustproof filter again, the photographer may feel annoyed. Further, when the dustproof filter is simply operated for each image pickup to remove dust, the dustproof filter operates even if no dust is attached, and thus there is a possibility that power is wasted.

  In the method disclosed in Patent Document 2, since the optical path for the finder and the optical path for imaging are different, even if dust is attached to the dustproof filter, it can be confirmed from the image for the finder. Can not.

  The present invention has been made in view of the above circumstances, and provides a digital camera that can remove dust by operating the dustproof filter only when dust is attached to the dustproof filter without any particular attention from the photographer. Objective.

  In order to achieve the above object, a digital camera according to a first aspect of the present invention includes a first imaging element, and captures a subject via a photographing lens to obtain a recording image. A second imaging unit that includes a means, an optical member disposed in front of the first imaging device, and a second imaging device, and captures an image of a subject through the photographing lens to obtain an image for finder observation. Determining means for comparing the recording image acquired by the first imaging means and the image for finder observation acquired by the second imaging means to determine the presence or absence of dust adhering to the optical member And an oscillating means that vibrates the optical member and removes the dust adhering to the optical member when it is determined by the determining means that the dust is attached to the optical member. And

  According to the first aspect, it is possible to determine the presence / absence of dust attached to the optical member by comparing the image acquired by the first imaging unit and the image acquired by the second imaging unit. The dust attached to the optical member can be removed by the vibration means only when the dust is attached.

  According to the present invention, it is possible to provide a digital camera that can remove dust by operating the dustproof filter only when dust adheres to the dustproof filter without any particular attention from the photographer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an external rear perspective view of a digital camera according to an embodiment of the present invention. A digital camera (hereinafter referred to as a camera) 1 in FIG. 1 shows a single-lens reflex digital camera with interchangeable lenses as an example. The camera 1 is mainly composed of a lens barrel 10 as an interchangeable lens and a camera body 30, and a desired lens barrel 10 is detachably set on the front surface of the camera body 30. .

  In FIG. 1, a release button 31, a mode dial 32, a power switch lever 33, a control dial 34, and the like are provided on the upper surface of the camera body 30.

  The release button 31 is a button for executing a shooting preparation operation and an exposure operation. The release button 31 is composed of a two-stage switch of a first release switch and a second release switch. When the release button 31 is pressed halfway, the first release switch is turned on to perform photometric processing or Shooting preparation operations such as distance measurement processing are executed. Further, when the release button 31 is fully pressed, the second release switch is turned on and the exposure operation is executed.

  The mode dial 32 is an operation member for setting a shooting mode at the time of shooting. When the mode dial 32 is rotated in a predetermined direction, a shooting mode at the time of shooting is set. The power switch lever 33 is an operation member for turning on / off the power of the camera 1. By turning the power switch lever 33, the main power supply of the camera 1 is switched on / off.

  The control dial 34 is a member for setting shooting information. By operating the control dial 34, various settings are performed during shooting.

  In FIG. 1, a liquid crystal monitor 36, a playback button 37, a cross key 40, an OK button 41, a finder 43, and the like are disposed on the back of the camera body 30.

  The liquid crystal monitor 36 is a monitor for displaying captured images, menus, and the like. The playback button 37 is a button for switching the operation mode of the camera 1 to a playback mode in which an image can be played back from a JPEG file recorded on a recording medium to be described later. The cross key 40 is an operation key for selecting each item on a menu screen or the like. The OK button 41 is an operation member for determining the selected item.

  FIG. 2 is a perspective view showing the configuration of the optical system inside the camera body in one embodiment of the present invention.

  This optical system includes a first reflecting mirror 51 for guiding a light beam from a subject that has passed through the photographing lens 11 in the lens barrel 10 in the direction of the finder optical system, a focusing screen (also referred to as a screen mat) 52, and a plurality of mirrors. A viewfinder optical system including the second reflection mirror 53, the third reflection mirror 54, and the fourth reflection mirror 55 shown in FIG.

  The first reflecting mirror 51 is configured to be pivotable in the direction of the arrow A in the figure about a shaft 51a. The first reflecting mirror 51 is in the position shown in FIG. 2 when observing the subject. In this case, the light beam incident from the photographing lens 11 is a second angle that is approximately 90 ° with respect to the optical axis of the photographing lens 11. The light is reflected in the direction of the reflection mirror 53, that is, in the right direction when viewed from the lens barrel 10 side of the camera body 30. In addition, the first reflecting mirror 51 is partially composed of a half mirror, and allows the light beam incident from the photographing lens 11 to pass through the half mirror portion and enter an AF sensor unit described later. On the other hand, the first reflecting mirror 51 retreats from the photographing optical path so that the light beam from the subject is guided to an imaging element (not shown) disposed behind the first reflecting mirror 51 during imaging.

  The light beam reflected by the reflecting surface of the first reflecting mirror 51 is imaged on the focusing screen 52. The focusing screen 52 has a diffusing surface for diffusing the light beam in order to form the light beam reflected by the first reflecting mirror 51 as an optical image. It is arranged at a position equivalent to. Further, the focusing screen 52 is formed with a distance measuring frame 52a for allowing the photographer to check the distance measuring range.

  The light beam that has passed through the focusing screen 52 enters the second reflection mirror 53. The second reflection mirror 53 is arranged on the reflection optical axis from the first reflection mirror 51, and the reflection surface thereof is inclined with respect to the reflection optical axis of the first reflection mirror 51 by a predetermined angle. A part of the reflected light beam from the first reflecting mirror 51 incident on the second reflecting mirror 53 is at an angle of about 90 ° with respect to the reflected optical axis from the first reflecting mirror 51, that is, above the camera body 30. Reflected towards.

  The light beam reflected by the reflection surface of the second reflection mirror 53 is on the reflection optical axis of the reflection surface of the second reflection mirror 53, and the reflection surface is relative to the reflection optical axis of the reflection surface of the second reflection mirror 53. The light enters the third reflection mirror 54 that is inclined at a predetermined angle. The reflected light beam from the second reflecting mirror 53 incident on the third reflecting mirror 54 is approximately 90 ° at the reflecting surface of the third reflecting mirror 54 with respect to the reflected optical axis from the reflecting surface of the second reflecting mirror 53. The angle is reflected toward the direction opposite to the reflection direction by the reflection surface of the first reflection mirror 51, that is, toward the left direction of the camera body 30.

  The light beam reflected by the reflecting surface of the third reflecting mirror 54 is on the reflecting optical axis of the reflecting surface of the third reflecting mirror 54, and the reflecting surface is relative to the reflecting optical axis of the reflecting surface of the third reflecting mirror 54. The light is incident on the fourth reflection mirror 55 that is inclined at a predetermined angle. A part of the reflected light beam from the third reflection mirror 54 incident on the fourth reflection mirror 55 is approximately 90 with respect to the reflection optical axis from the third reflection mirror 54 on the reflection surface of the fourth reflection mirror 55. Reflected at an angle of °. Thus, the reflected light beam from the reflection surface of the third reflection mirror 54 is incident on the eyepiece lens 57 disposed on the reflection optical axis of the reflection surface of the fourth reflection mirror 55. In this way, the subject image formed on the focusing screen 52 is inverted so as to be an erect image and guided to the eyepiece lens 57. Accordingly, the subject image formed on the focusing screen 52 by the photographer's eye 58 can be observed through the eyepiece lens 57 (finder 43).

  Here, the second reflection mirror 53 and the fourth reflection mirror 55 are constituted by half mirrors, and a photometric sensor 63 for measuring the brightness of the subject is disposed on the back surface side of the reflection surface of the second reflection mirror 53. Has been. On the other hand, an imaging lens 60 and a display image sensor 61 are disposed on the back surface side of the reflection surface of the fourth reflection mirror 55. The display imaging element 61 as the second imaging means is a photoelectric conversion element for acquiring an image of a subject imaged on the focusing screen 52 via the imaging lens 60. Although the image of the subject formed on the image sensor 61 for display is inverted by 180 ° with respect to the image of the actual subject, it has the same angle of view as the image seen by the photographer's eye 58 through the eyepiece lens 57. An image is obtained. Thus, the image obtained by the display image sensor 61 is read out in an appropriate order by an interface circuit described later, and then displayed as an image on the liquid crystal monitor 36, for example. If such display is continuously performed, an image similar to the image that can be seen by the photographer via the eyepiece lens 57 can be displayed on the liquid crystal monitor 36 or the like. Such a display method is called live view display or live view display.

  In the example of FIG. 2, the first reflecting mirror 51, the second reflecting mirror 53, the third reflecting mirror 54, and the fourth reflecting mirror 55 are arranged so as to reflect the incident light beam at an angle of approximately 90 °. However, it is not limited to this.

  FIG. 3 is a block diagram showing the system configuration of the camera according to one embodiment of the present invention. In FIG. 3, the lens barrel 10 is configured to be detachable via a lens mount (not shown) provided on the front surface of the camera body 30.

  The lens barrel 10 includes a photographic lens 11, a diaphragm 12, a lens driving mechanism 13, a diaphragm driving mechanism 14, and a lens control microcomputer (hereinafter referred to as Lμcom) 15. The photographing lens 11 is driven in the optical axis direction by a DC motor (not shown) existing in the lens driving mechanism 13. The diaphragm 12 is driven to open and close by a stepping motor (not shown) existing in the diaphragm drive mechanism 14. The Lμcom 15 drives and controls each part in the lens barrel 10 such as the lens driving mechanism 13 and the aperture driving mechanism 14. The Lμcom 15 is electrically connected to a later-described body control microcomputer (hereinafter referred to as Bμcom) 80 via the communication connector 20, and is controlled in accordance with a command of the Bμcom 80. In other words, the Bμcom 80 and the Lμcom 15 are electrically connected so that they can communicate with each other via the communication connector 20 when the lens barrel 10 is mounted, so that the Lμcom 15 operates as a digital camera in cooperation with the Bμcom 80 in a dependent manner. It has become.

  On the other hand, the camera body 30 is provided with an optical system as shown in FIG. That is, at the time of observing the subject, a light beam from a subject (not shown) that is incident through the photographing lens 11 and the diaphragm 12 in the lens barrel 10 is reflected by the first reflecting mirror 51, and the focusing screen 52 and the second to second focusing screens. The eyepiece lens 57 is reached via a finder optical system 56 (shown collectively in FIG. 3) composed of a fourth reflecting mirror. Here, the first reflection mirror 51 is driven by the mirror drive mechanism 73. Further, a display image sensor 61 is disposed in the vicinity of the finder optical system 56 shown in FIG. 3 (in the vicinity of the fourth reflection mirror 55 in FIG. 2), and the photographing lens 11 in the lens barrel 10 is arranged. A light beam from a subject (not shown) incident through the stop 12 is received and converted into an electric signal. Further, a photometric sensor 63 is provided in the vicinity of the finder optical system 56. The output of the photometric sensor 63 is input to the photometric circuit 87. The photometric circuit 87 performs a well-known photometric process based on the input from the photometric sensor 63.

  Further, a part of the subject luminous flux that has passed through the half mirror portion of the first reflecting mirror 51 is installed on the back surface of the first reflecting mirror 51 and is reflected by the sub-mirror 70 interlocking with the first reflecting mirror 51 to automatically measure the distance. To the AF sensor unit 71 for performing the above. The AF sensor unit 71 is driven and controlled by an AF sensor driving circuit 72.

Further, on the optical axis of the photographing lens 11 and behind the first reflection mirror 51, a shutter 66, a dustproof filter 67, and a recording image sensor 68 are arranged.
The shutter 66 is a focal plane type shutter composed of, for example, a front curtain and a rear curtain, and adjusts the amount of incident light flux on the imaging surface by shielding or exposing the imaging surface of the recording image sensor 68. . The spring for driving the front curtain and the rear curtain of the shutter 66 is charged by the shutter charge mechanism 75. Further, the shutter control circuit 76 controls the operation of the front curtain and rear curtain of the shutter 66. The operations of the shutter charge mechanism 75 and the shutter control circuit 76 are controlled by the Bμcom 80.

  A dustproof filter 67 as an optical member is disposed in front of the recording image pickup element 68 and prevents dust from entering the image pickup surface of the recording image pickup element 68. In addition, a piezoelectric element 67a is attached to the peripheral portion of the dustproof filter 67, and a standing wave is generated on the surface of the dustproof filter 67 by vibrating the piezoelectric element 67a, and the surface of the dustproof filter 67 is caused by the vibration. Dust adhering to is removed. The piezoelectric element 67 a is driven by a dustproof filter driving circuit 77. The operation of the dustproof filter driving circuit 77 is controlled by Bμcom80. Here, the piezoelectric element 67a and the dustproof filter driving circuit 77 constitute a vibration means. A temperature measurement circuit 78 is provided in the vicinity of the dust filter 67. Usually, the temperature affects the elastic modulus of a glass material. That is, since the change in temperature becomes one of the factors that change the natural frequency of the dust filter 67, the ambient temperature is always measured by the temperature measuring circuit 78 when the dust filter 67 is vibrated. The temperature measurement point of the temperature measurement circuit 78 is preferably set in the vicinity of the vibration surface of the dust filter 67. In this way, by controlling the vibration of the dust filter 67 while considering the change in temperature, it is possible to always vibrate the dust filter 67 under optimum conditions.

  The recording image pickup element 68 as the first image pickup means is a photoelectric conversion element for photoelectrically converting a subject image that has passed through the photographing lens 11, and is composed of a CCD image sensor or the like. That is, when the first reflecting mirror 51 is retracted from the photographing optical path, the light flux that has passed through the photographing lens 11 and the diaphragm 12 is imaged on the imaging surface of the recording imaging element 68 and converted into an electrical signal.

  In FIG. 3, the display image sensor 61 and the recording image sensor 68 are connected to an image processing controller 82 for performing image processing via an interface circuit 81. The image processing controller 82 is connected to the liquid crystal monitor 36, the SDRAM 83, the FlashRom 84, the recording medium 85, and the like.

  The image processing controller 82 performs various image processing such as white balance correction processing and gradation correction processing on the image data input through the interface circuit 81. The image processing controller 82 also compresses the processed image data by various methods such as the JPEG method.

  The SDRAM 83 is a storage medium that temporarily stores various data such as processing data of the image processing controller 82. The FlashRom 84 is a storage medium that stores a control program for the camera.

  The recording medium 85 is an external recording medium such as various memory cards that can be attached to and detached from the camera body 30 via a recording interface (not shown) and an external hard disk drive (HDD).

  In addition, the image processing controller 82 includes a photometering circuit 87, an AF sensor driving circuit 72, a mirror driving mechanism 73, a shutter charging mechanism 75, a shutter control circuit 76, and a nonvolatile memory (EEPROM) 88, and the camera body 30. It is connected to a body control microcomputer (Bμcom) 80 for controlling each part. Further, an operation display LCD 90 for notifying the photographer of the operation state of the camera by display output, a camera operation switch (SW) 91, and a battery 93 via a power supply circuit 92 are connected to the Bμcom 80. Has been.

  The non-volatile memory 88 is a storage medium for storing predetermined control parameters necessary for camera control as a storage area other than the above-described SDRAM 83, FlashRom 84, and recording medium 85, and is provided so as to be accessible from the Bμcom 80.

  The operation display LCD 90 is for notifying the user of the operation state of the camera by display output. For example, the camera operation switch 91 operates in conjunction with the operation of the release button 31 to instruct the execution of the photographing operation and to operate the release switch and the mode dial 32 for moving the first reflecting mirror 51 forward and backward as described later. Operates by operating the operation members necessary to operate the camera, such as a mode change switch that operates in conjunction with it and switches between a shooting mode and an image display mode, and a power switch that turns on and off in conjunction with the operation of the power switch lever 33. It consists of a group of switches. Further, the power supply circuit 92 is provided for converting the voltage of the battery 93 as a power supply into a voltage required by each circuit unit of the camera system and supplying the voltage.

  Next, the photographing operation in the through image mode in the camera having the above configuration will be described with reference to the flowchart of FIG. The process of FIG. 4 is performed by a Bμcom 80 serving as a determination unit provided inside the camera body 30.

  For example, when the photographer switches to the live view mode by operating the mode dial 32, the process of FIG. 4 is started. First, the Bμcom 80 selects the display image sensor 61 so that a through image display can be performed (step S1). As a result, the signal from the display image sensor 61 is read out by the interface circuit 81. Subsequently, the Bμcom 80 sends an instruction to the image processing controller 82 to display a through image on the liquid crystal monitor 36 based on the signal read from the display image sensor 61 (step S2). As a result, a finder image equivalent to an image that can be observed through the eyepiece lens 57 is displayed on the liquid crystal monitor 36.

  Subsequently, the Bμcom 80 determines whether or not the first release switch among the release switches is turned on (step S3). If it is determined in step S3 that the first release switch is not turned on, step S3 is branched to step S4, and the Bμcom 80 determines whether or not a mode change operation from the through image mode has been performed by the photographer. Determine (step S4). If the mode change operation is not performed in the determination in step S4, the process returns to step S3. On the other hand, when the mode change operation is performed, the Bμcom 80 ends the processing of FIG. 4 and returns to the flowchart of the main operation (not shown), and performs processing according to the changed mode.

  If it is determined in step S3 that the first release switch is turned on, step S3 is branched to step S5, and the Bμcom 80 determines the aperture amount at the time of photographing based on the result of the photometric processing in the photometric circuit 87 and An exposure amount calculation for calculating the shutter speed is performed (step S5). Subsequently, the Bμcom 80 performs a distance measurement calculation that calculates the focus state of the photographic lens 11 based on the result processed by the AF sensor drive circuit 72 based on the output of the AF sensor unit 71, and the calculation result is transmitted to the communication connector 20. Communicate to Lμcom 15 via. The Lμcom 15 calculates the driving amount of the photographing lens 11 based on the focus state of the photographing lens 11 communicated from the Bμcom 80, and drives the photographing lens 11 via the lens driving mechanism 13 based on this driving amount, thereby taking the photographing lens 11. Is adjusted (step S6). As a result, when the in-focus state is obtained, the Bμcom 80 displays on the finder 43 and the liquid crystal monitor 36 that the in-focus state has been obtained (step S7).

  Next, the Bμcom 80 determines whether or not the second release switch among the release switches is turned on (step S8). If it is determined in step S8 that the second release switch is not on, step S8 is branched to step S9, and the Bμcom 80 determines again whether or not the first release switch is on (step S8). S9). If it is determined in step S9 that the first release switch is on, the process returns to step S8. On the other hand, if the first release switch is not on, the process returns to step S3.

  If it is determined in step S8 that the second release switch is on, step S8 is branched to step S10, and the Bμcom 80 instructs the image processing controller 82 to stop displaying the through image (step S10). ). Then, the Bμcom 80 stores the last (latest) frame image captured by the display image sensor 61 during the through image display in the SDRAM 83 (step S11). Next, in order to perform image recording, the Bμcom 80 selects the recording image sensor 68 (step S12). Thus, the interface circuit 81 is set so that the signal from the recording image sensor 68 is read out. Subsequently, the Bμcom 80 retracts the first reflecting mirror 51 from the photographing optical path via the mirror driving mechanism 73 (step S13), and performs a photographing operation for acquiring a recording image obtained by the recording image sensor 86 (step S13). S14). After the photographing operation is finished, the Bμcom 80 returns the first reflecting mirror 51 to the photographing optical path via the mirror driving mechanism 73 (step S15).

  Next, the Bμcom 80 performs dust detection processing for detecting whether dust is attached to the dust filter 67 (step S16). This dust detection process will be described in detail later. After the dust detection process, the image obtained by the recording image sensor 86 is image-processed by the image processing controller 82 and then recorded on the recording medium 85 (step S17). Subsequently, the Bμcom 80 determines whether or not a mode change operation from the through image mode has been performed by the photographer (step S18). If it is determined in step S18 that no mode change operation has been performed, the process returns to step S1. On the other hand, when the mode change operation is performed, the Bμcom 80 ends the processing of FIG. 4 and returns to the flowchart of the main operation (not shown), and performs processing according to the changed mode.

  Next, the dust detection process in step S16 in FIG. 4 will be described with reference to the flowchart in FIG.

  In the dust detection process, the Bμcom 80 first instructs the image processing controller 82 to resize the latest through image stored in the SDRAM 83 in step S11 of FIG. 4 to the same size as the image obtained by the recording image sensor 68. (Step S21). In general, the display image sensor 61 is often configured with an image sensor having a smaller number of pixels than the recording image sensor 68 so that high-speed imaging can be performed. In order to perform dust detection by comparing with the image obtained by the image pickup device 68, it is necessary to perform a process for equalizing the image sizes of both the images. The resizing process can be performed using, for example, an interpolation calculation.

  After equalizing the image size of the image obtained by the image sensor for display 61 and the image obtained by the image sensor for recording 68, Bμcom 80 is obtained by the image sensor obtained by the image sensor for recording 68 and the image sensor 61 for display. An instruction is sent to the image processing controller 82 so as to normalize the white balance of the received image (step S22). In this white balance normalization process, both the whitest portions of the image obtained by the recording image sensor 68 and the image obtained by the display image sensor 61 have the same predetermined white color (for example, pure white). In addition, each of the R, G, and B components of both image data is corrected. Thereby, the color tone of the image obtained by the recording image sensor 68 and the color tone of the image obtained by the display image sensor 61 become equal.

  After normalizing the white balance, the Bμcom 80 calculates the difference image between the image obtained by the recording image sensor 68 and the image obtained by the display image sensor 61 for each pixel. An instruction is sent to 82 (step S23). After calculating the difference image, the Bμcom 80 sends an instruction to the image processing controller 82 to remove the image of the portion related to the predetermined fixed pattern image from the obtained difference image (step S24). . Here, the fixed pattern image is, for example, an image of a distance measuring frame 52 a formed on the focusing screen 52. The image of the distance measuring frame 52 a is an image obtained by the display image sensor 61, but cannot be obtained by the recording image sensor 68. In other words, in the fixed pattern portion, there is a difference between the image obtained by the recording image sensor 68 and the image obtained by the display image sensor 61 even if no dust adheres to the dust filter 67. For this reason, the image of the fixed pattern portion is removed. Here, the fixed pattern image data is, for example, stored in the nonvolatile memory 88.

  In this way, by removing the image of the fixed pattern portion, it is possible to prevent the fixed pattern portion from being mistaken for dust. Note that the removal of the fixed pattern image may be performed prior to the calculation of the difference image. In this case, after the image of the fixed pattern portion is removed, the difference may be calculated after the removed portion is interpolated by interpolation.

  After removing the difference image of the fixed pattern portion, the Bμcom 80 counts the number of pixels whose difference is not “0” (step S25). Since the fixed pattern image is removed in step S24, the image obtained by the recording image sensor 68 and the image obtained by the display image sensor 61 should be substantially equivalent. That is, the difference between the image obtained by the recording image sensor 68 and the image obtained by the display image sensor 61 is due to dust adhering to the dust-proof filter 67 disposed on the front surface of the recording image sensor 68. Can be considered. In step S25, the number of pixels whose difference is not “0” is counted. However, if the difference is within a certain threshold, it may be regarded as “0”.

  After counting the number of pixels whose difference is not “0”, the Bμcom 80 calculates the ratio of the total number of pixels whose difference is not “0” (step S26). Then, the Bμcom 80 determines whether or not the ratio of pixels whose difference is not “0” is equal to or greater than m% (for example, about 10%) (step S27). In the determination of step S27, when the ratio of pixels where the difference is not “0” is less than m%, no dust or only a small amount of dust is attached to the dustproof filter 67, so the flowchart of FIG. The process ends, and the process proceeds to step S17 in the flowchart of FIG. On the other hand, if the percentage of pixels where the difference is not “0” is greater than or equal to m%, step S27 is branched to step S28, and the Bμcom 80 vibrates the piezoelectric element 67a via the dustproof filter drive circuit 77, thereby preventing dust. Dust adhering to the filter 67 is removed (step S28). Thereafter, a display indicating that dust has adhered to the dustproof filter 67 is performed on the operation display LCD 90, for example (step S29). Thereafter, the process of the flowchart of FIG. 5 is terminated, and the process proceeds to step S17 of the flowchart of FIG.

  As described above, according to the present embodiment, even a digital camera using an optical system in which the optical path for the finder and the optical path for imaging are different is acquired via the optical path for the finder. By calculating the difference between the captured image and the image acquired via the imaging optical path, the dust filter is vibrated only when dust adheres to the dust filter without any particular attention from the photographer. Can be removed.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above-described embodiments, and various modifications and applications are naturally possible within the scope of the gist of the present invention. For example, the value of m in step S27 in FIG. 5 can be changed as appropriate. Further, the warning in step S29 may not be performed on the operation display LCD 90. Further, the warning is not limited to display.

  Further, the above-described embodiments include various stages of the invention, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.

1 is an external rear perspective view of a digital camera according to an embodiment of the present invention. It is a perspective view which shows the structure of the optical system inside a camera main body in one Embodiment of this invention. It is a block diagram which shows the system configuration | structure of the camera which concerns on one Embodiment of this invention. 6 is a flowchart illustrating a shooting operation in a through image mode in the camera according to the embodiment of the present invention. It is a flowchart shown about a dust detection process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Digital camera (camera), 10 ... Lens barrel, 11 ... Shooting lens, 13 ... Lens drive mechanism, 14 ... Diaphragm drive mechanism, 15 ... Microcomputer for lens control (L [mu] com), 20 ... Communication connector, 30 ... Camera Main body 36 ... Liquid crystal monitor 55 ... First reflection mirror 56 ... Viewfinder optical system 57 ... Eyepiece lens 61 ... Display image sensor 63 ... Photometric sensor 66 ... Shutter 67 ... Dustproof filter 67a ... Piezoelectric element 68 ... Recording image sensor, 70 ... Sub mirror, 71 ... AF sensor unit, 72 ... AF sensor drive circuit, 73 ... Mirror drive mechanism, 75 ... Shutter charge mechanism, 76 ... Shutter control circuit, 77 ... Dustproof filter drive circuit, 78 ... Temperature measuring circuit, 80 ... Microcomputer for body control (Bμcom), 81 ... Interface times , 82... Image processing controller, 83... SDRAM, 84... FlashRom, 85... Recording medium, 86... Recording image sensor, 87 .. photometric circuit, 88 .. non-volatile memory (EEPROM), 90. ... Camera operation switch, 92 ... Power supply circuit, 93 ... Battery

Claims (5)

A first imaging unit including a first imaging element and capturing an image of a subject through a photographing lens to obtain a recording image;
An optical member disposed in front of the first image sensor;
A second image pickup unit including a second image pickup element, picking up an image of a subject through the photographing lens and acquiring an image for finder observation;
A determination unit for comparing the image for recording acquired by the first imaging unit and the image for finder observation acquired by the second imaging unit to determine the presence or absence of dust attached to the optical member;
Vibration means for vibrating the optical member to remove the dust adhering to the optical member when the determining means determines that dust is attached to the optical member;
A digital camera comprising:   The determination unit includes an adjustment unit that adjusts the finder observation image acquired by the second imaging unit so as to coincide with the recording image acquired by the first imaging unit, and the adjustment by the adjustment unit The digital camera according to claim 1, wherein the determination is performed after the determination.   The digital camera according to claim 2, wherein the adjustment unit performs the adjustment so that an image size and a color tone of the image for finder observation and the image for recording are matched.   The digital camera according to claim 1, wherein the determination unit removes an image of a fixed pattern included in the image for finder observation when determining the presence or absence of the dust.   2. The digital camera according to claim 1, further comprising warning means for giving a warning when the determination means determines that dust is attached to the optical member.

Images