JP2010141574A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device which efficiently performs cleaning operation and saves power consumption for photographing over a longer time, and to provide a control method of the same. <P>SOLUTION: The imaging device detects the aperture value of a lens attached to a camera body, when photographing, and changes the driving time and the driving frequency of a drive means, according to the information. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus such as an electronic still camera having a cleaning mode for removing dust adhering to an imaging element, an optical low-pass filter, and the like, and a method for controlling the cleaning mode.

  In an imaging apparatus such as a digital camera that converts an image signal into an electrical signal and captures an image, the imaging light beam is received by an imaging element such as a CCD or C-MOS sensor, and a photoelectric conversion signal output from the imaging element is converted into image data. The data is converted and recorded on a recording medium such as a memory card. In such an image pickup device, an optical low-pass filter or an infrared cut filter is disposed on the front side of the image pickup element. If foreign matter such as dust adheres to the surface of the image pickup element, the optical low-pass filter or the infrared cut filter, the attachment The portion becomes a black dot and appears in the photographed image, and the appearance of the image deteriorates.

  Especially in digital SLR cameras with interchangeable lenses, mechanical operation parts such as shutters and quick return mirrors are arranged in the vicinity of the image sensor, and foreign matters such as dust generated from these operation parts May adhere to the low-pass filter. Further, when the lens is exchanged, dust or the like may enter the camera body from the opening of the lens mount and adhere to it.

Therefore, in order to solve the above-mentioned problems, there is one that removes foreign matters such as dust attached to the surface of the dust-proof member by vibrating a dust-proof member that transmits light on the front surface of the imaging device with a piezoelectric element. (For example, refer to Patent Document 1).
JP2003-319222

  However, the above-described conventional technology is for allowing the user to periodically clean in order to remove dust, and the aperture value at the time of shooting of the lens attached to the camera body and the dust adhering to the image sensor are It does not take into consideration how much the image is actually taken. Therefore, even if the dust that has adhered to the image sensor is hardly captured as a captured image, for example, even when the photographing lens has a large aperture, cleaning is performed periodically. Therefore, it cannot be said that the cleaning operation is very efficient.

  Therefore, the object of the present invention is to detect the aperture value at the time of shooting of the lens attached to the camera body, perform the cleaning operation efficiently based on the information, and eliminate unnecessary power consumption. It is an object to provide an imaging apparatus that can perform long-time imaging and a control method thereof.

In order to achieve the above object, the first configuration of the invention according to the present application is as follows:
A mount part to which the taking lens can be attached and detached;
Detecting means for detecting the mounting and aperture value of the photographing lens;
Imaging means for converting an optical image of a subject into an electrical signal;
An optical element disposed in front of the imaging means;
In an imaging apparatus having a drive cutoff that vibrates the optical element,
Setting means for setting a vibration mode of the drive means based on the state detected by the detection means;
The driving means is driven by the set vibration mode.

The second configuration of the invention according to the present application for achieving the above object is as follows:
In the first configuration, the setting unit sets the vibration mode for one of a driving time and a driving frequency of the driving unit, or a combination thereof.

  According to the present invention, by detecting the aperture value at the time of photographing of the lens attached to the camera body, the driving time and the driving frequency of the driving means are changed according to the information, thereby efficiently cleaning. By performing the operation and eliminating unnecessary power consumption, it is possible to provide an imaging apparatus capable of shooting for a longer time and a control method thereof.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

[Camera description]
Hereinafter, a preferred first embodiment of the present invention will be described in detail with reference to the drawings.

  An imaging apparatus to which the present invention is applied will be described with reference to FIGS. 1 and 2 are external views of a digital single-lens reflex camera according to an embodiment of the present invention, and FIG. 3 is a block diagram illustrating an electrical configuration of the digital single-lens reflex camera. FIG. 1 is a perspective view as seen from the front of the camera, showing a state in which the taking lens unit is removed. FIG. 2 is a perspective view seen from the back side of the camera.

  In FIG. 1, reference numeral 1 denotes a camera housing, which is provided with a grip portion 1a that protrudes forward so that a user can easily hold the camera stably during photographing. Reference numeral 2 denotes a mount, which is a part where a detachable photographic lens (not shown) is attached to the camera body. The mount contact 21 has a function of transmitting a control signal, a status signal, a data signal, and the like between the camera body and the photographing lens unit and supplying currents of various voltages. Further, the mount contact 21 may be configured not only for electrical communication but also for optical communication, voice communication, and the like.

  Reference numeral 4 denotes a lens lock release button that is pushed in when removing the photographing lens unit. Reference numeral 5 denotes a mirror box arranged in the camera casing, which has a shape surrounding a light beam that has passed through the photographing lens. In addition, a quick return mirror 6 is built in that is held at an angle of 45 ° in order to guide the light passing through the photographing lens to the pentaprism 22 (see FIG. 3) and the viewfinder eyepiece window 18.

  To the left of the upper part of the camera (as viewed from the front), a shutter button 7 as a start switch for starting shooting, a main operation dial 8 for setting a shutter speed and a lens aperture value according to an operation mode at the time of shooting, and a camera An LCD display panel 9 showing each operation mode and an upper surface operation mode setting button 10 of the photographing system are arranged. The shutter button 7 is configured such that SW1_7a is turned on in the first stroke and SW2_7b is turned on in the second stroke.

  The top operation mode setting button 10 is used for setting whether continuous shooting or only one frame shooting is performed when the shutter button 7 is pressed once, setting a self-shooting mode, and the like. The setting status is displayed on the device 9. The contents displayed on the external liquid crystal display device 9 will be described in detail later with reference to FIG.

  A flash unit 11 that pops up with respect to the camera body, a shoe groove 12 for attaching a flash, and a flash contact 13 are located at the upper center of the camera, and a shooting mode setting dial 14 is disposed from the upper right of the camera.

  An openable / closable external terminal cover 15 is provided on the right side of the camera, and a video signal output jack 16 and a USB output connector 17 are housed inside the cover 15 as an external interface.

  A finder eyepiece window 18 is provided above the center of the optical axis on the back of the camera, and a color liquid crystal display 19 capable of displaying an image is provided at the center of the back of the camera. The sub operation dial 20 arranged beside the color liquid crystal display unit 19 plays an auxiliary role of the function of the main operation dial 8, and for example, in the AE mode of the camera, the exposure correction amount with respect to the appropriate exposure value calculated by the automatic exposure device. Used to set Alternatively, in the manual mode in which each of the shutter speed and the lens aperture value is set according to the user's will, the shutter speed is set with the main operation dial 8 and the lens aperture value is set with the sub operation dial 20. The sub operation dial 20 is also used as a display selection unit for a captured image displayed on the color liquid crystal display unit 19.

  A main switch 43 prohibits all operations of the digital single-lens reflex camera.

  Reference numeral 44 denotes a cleaning mode operation member, which activates an operation to screen off dust adhering to a low-pass filter described later.

  FIG. 3 is a block diagram showing an electrical configuration built in the digital camera having the above-described configuration, and the same components as those in FIGS.

  In FIG. 3, reference numeral 100 denotes a central processing unit (hereinafter referred to as MPU) of a microcomputer built in the camera body. The MPU 100 corresponds to the control means.

  Reference numeral 100a denotes an EEPROM built in the MPU 100, which can store clock information of the clock measuring circuit 109 and other photographing information.

  The MPU 100 includes a mirror drive circuit 101, a focus detection circuit 102, a shutter drive circuit 103, a video signal processing circuit 104, a switch sense circuit 105, a photometry circuit 106, a liquid crystal display drive circuit 107, a battery check circuit 108, a time measurement circuit 109, A power supply circuit 110 and a piezoelectric element drive circuit 111 are connected. The MPU 100 sequentially controls each element and the circuit in a predetermined order.

The MPU 100 communicates with the lens control circuit 201 disposed in the photographing lens via the mount contact 21 shown in FIG. The mount contact 21 also has a function of transmitting a signal to the MPU 100 when the photographic lens unit is connected. As a result, it is possible to communicate between the camera body and the photographic lens unit to drive the photographic lens 200 and the diaphragm 204 in the photographic lens unit.
In this embodiment, for convenience, a single photographic lens is shown. However, as is well known, it is actually composed of a larger number of lenses.

  Reference numeral 202 denotes an AF (autofocus) drive circuit, which is constituted by, for example, a stepping motor, and focuses on the image sensor 33 by changing the focus lens position in the photographing lens 200 under the control of the lens control circuit 201 in response to an instruction from the MPU 100. Adjust. Reference numeral 203 denotes an aperture drive circuit, which is constituted by, for example, an auto iris, and changes the optical aperture value by changing the aperture 204 under the control of the lens control circuit 201 in response to an instruction from the MPU 100.

  A main mirror 6 guides the subject image formed by the photographing lens 200 to the pentaprism 22 and transmits part of the image to the focus detection sensor unit 31 through a sub-mirror 30 to be described later. Thus, the position where the subject image can be observed with the finder and the retreat position where the subject image is retracted from the optical path of the subject light beam during photographing are configured to be movable.

  Reference numeral 30 denotes a sub-mirror for reflecting the subject light transmitted through a part of the main mirror 6 and guiding the subject image to the focus detection sensor unit 31. The sub mirror 30 is linked to the main mirror 6 or the mirror driving circuit 101 of the main mirror 6. When the main mirror 6 is at a position where the subject image can be observed with the finder, the main mirror 6 is movable to a position for guiding the subject light to the focus detection sensor 31 and to a retreat position for retracting from the optical path of the subject luminous flux at the time of photographing. Has been.

  Reference numeral 31 is a well-known phase difference type focus detection composed of a field lens, a reflection mirror, a secondary imaging lens, a diaphragm, a line sensor composed of a plurality of CCDs, etc., arranged in the vicinity of an imaging surface (not shown). It is a sensor unit.

  Reference numeral 101 denotes a mirror drive circuit, which includes, for example, a DC motor and a gear train, and drives the main mirror 6 and the sub mirror 30 under the control of the MPU 100.

  Reference numeral 22 denotes a pentaprism, which is an optical member that converts and reflects a subject image guided by the main mirror 6 into an erect image. The subject luminous flux that has passed through the photographing lens 200 passes through the stop 204, is reflected by the main mirror 6, is guided to the pentaprism 22, and the subject image is observed through the finder eyepiece window 18. Further, the light is also guided to the photometric sensor 37.

  Further, the light beam transmitted through the main mirror 6 is reflected by the sub-mirror 30 and re-imaged on the detection surface of the focus detection sensor unit 31 placed at a position substantially equivalent to the surface of the image sensor 33. The optical image is converted into an electrical image signal and supplied to the focus detection circuit 102.

  The focus detection circuit 102 performs accumulation control and readout control of the focus detection sensor unit 31 according to the signal of the MPU 100, and outputs pixel information to the MPU 100. Based on the image signal of the subject image from the focus detection circuit 102, the MPU 100 performs focus detection calculation by the phase difference detection method. Then, the difference between the imaging plane formed by the photographic lens 200 and the planned imaging plane such as a film plane, that is, the defocus amount and the defocus direction is obtained. Based on the calculated defocus amount and defocus direction, the MPU 100 changes the focus lens position in the photographic lens 200 via the lens control circuit 201 and the AF drive circuit 202 and drives it to the in-focus position.

  Reference numeral 32 denotes a mechanical shutter device that blocks a subject light beam during viewfinder observation. The front blade group (not shown) is retracted from the optical path of the subject luminous flux according to the release signal at the time of imaging, and is retracted from the optical path of the subject luminous flux at the time of finder observation. It is a focal plane shutter having a rear blade group (not shown) that shields the subject luminous flux at a predetermined timing after the start. The mechanical shutter device 32 is controlled by a shutter drive circuit 103 that has received a command from the MPU 100.

  In the present embodiment, the case of having both the front blade group and the rear blade group is described, but when starting exposure with only one shielding member, the subject light beam is retracted from the optical path, It is good also as a structure which returns to the position which shields the optical path of a to-be-photographed light beam again after completion | finish of imaging | photography.

  Reference numeral 33 denotes an image sensor, which uses a CMOS sensor that is a two-dimensional imaging device. There are various types of imaging devices such as a CCD type, a CMOS type, and a CID type, and any type of imaging device may be adopted. In the present embodiment, a CMOS type image sensor is employed.

  Reference numeral 34 denotes a clamp / CDS (correlated double sampling) circuit, which performs basic analog processing before A / D conversion and can also change the clamp level. Reference numeral 35 denotes an AGC (automatic gain adjusting device) which performs basic analog processing before A / D conversion and can change the AGC basic level. Reference numeral 36 denotes an A / D converter that converts an analog output signal of the image sensor 33 into a digital signal.

  410 is an optical low-pass filter. In this embodiment, a low-pass filter is constructed by laminating and laminating a plurality of birefringent plates made of quartz, a phase plate, and a birefringent plate, and an infrared cut filter is further laminated. Has been. By making the rectangular shape substantially the same shape as the effective light beam and making the expensive optical low-pass filter as small as possible, the price can be reduced.

  A laminated piezoelectric element 430 is configured to be excited by the piezoelectric element driving circuit 111 that receives a command from the MPU 100 and transmit the vibration to the optical low-pass filter 410.

  Reference numeral 400 denotes an image pickup unit unitized together with the optical low-pass filter 410, the piezoelectric element 430, the image pickup element 33, and other components to be described later.

  Reference numeral 104 denotes a video signal processing circuit, which is responsible for overall image processing by hardware such as gamma / knee processing, filter processing, and information composition processing for monitor display on the digitized image data of the image sensor 33. The image data for monitor display from the video signal processing circuit 104 is displayed on the color liquid crystal display 19 via the color liquid crystal driving circuit 109. Switching of these functions is performed by exchanging data with the MPU 100, and the white balance information of the output signal of the image sensor 33 can be output to the MPU 100 as necessary. Based on the information, the MPU 100 can perform white balance adjustment and gain. Make adjustments.

  Further, it is possible to store image data in the buffer memory 37 through the memory controller 38 without doing anything in accordance with an instruction from the MPU 100. The video signal processing circuit 104 also has a function of performing compression processing such as JPEG. In the case of continuous shooting, image data is temporarily stored in the buffer memory 37. When processing time is long, unprocessed image data is read through the memory controller 38, and image processing and compression processing are performed by the video signal processing circuit 104. , It is configured to increase the continuous shooting speed. The number of continuous shots greatly depends on the capacity of the buffer memory 37.

  The memory controller 38 stores unprocessed digital image data input from the video signal processing circuit 104 in the buffer memory 37. Then, the processed digital image data is stored in the memory 39, or conversely, the image data is output from the buffer memory 37 or the memory 39 to the video signal processing circuit 104. Further, the memory controller 38 stores the video transmitted from the external interface 40 (corresponding to the video signal output jack 16 and the USB output connector 17 in FIG. 1) in the memory 39 or stored in the memory 39. Images can be output from the external interface 40. The memory 39 can be detached from the camera body.

  Reference numeral 105 denotes a switch sense circuit, which controls each unit according to the operation state of each switch. 7a is a switch SW1 which is turned on by the first stroke of the release button 7. Reference numeral 7b denotes a switch SW2 which is turned on by the second stroke of the release button 7. When the switch SW2 is turned on, the release operation is started. Further, the main operation dial 8, the sub operation dial 20, the photographing mode setting dial 14, the main switch 43, and the cleaning mode operation member 44 are connected, and the state of each SW is transmitted to the MPU 100.

  The switch sense circuit 105, the main switch 43, and the MPU 100 constitute a power switch. When it is detected that the power switch is turned on, power supply from the power source 42 to the camera body is started.

  Reference numeral 106 denotes a photometric circuit, which outputs an output from the photometric sensor 37 to the MPU 100 as a luminance signal of each area in the screen. The MPU 100 A / D converts the luminance signal and calculates the exposure for shooting.

  Reference numeral 107 denotes a liquid crystal display driving circuit, which drives the external liquid crystal display device 9 and the in-finder liquid crystal display device 41 in accordance with the display content command of the MPU 100. Further, the liquid crystal display driving circuit 107 can put a specific segment in a blinking display state according to an instruction from the MPU 100.

The liquid crystal display driving circuit 107 and the external liquid crystal display 9 constitute display means, and the liquid crystal display driving circuit 107 and MPU 100 constitute display control means 108 is a battery check circuit, A battery check is performed for a predetermined time according to the signal, and the detection output is sent to the MPU 100.

  The battery check circuit 108 and the MPU 100 constitute battery check means.

  Reference numeral 109 denotes a time measuring circuit that measures the time and date from when the main switch 43 is turned off to when it is turned on, and can send the measurement result to the MPU 100 in accordance with an instruction from the MPU 100.

The time measuring circuit 109 and the MPU 100 constitute a measuring means.
A power supply unit 42 supplies power necessary for each IC (integrated circuit) and drive system.

[Description of imaging unit]
Next, a detailed configuration of the imaging unit 400 of the present embodiment will be described below with reference to FIGS. FIG. 4 is an exploded perspective view showing a schematic configuration inside the camera for showing the configuration and holding structure of the imaging unit 400. FIG. 5 is a front view showing a part of the constituent members of the imaging unit 400. FIG. 6 is a perspective view showing the configuration of the imaging unit 400, and FIG. 7 is a perspective view showing a detailed configuration around the low-pass filter and the imaging device. As shown in FIG. 4, a shutter unit 32, a main body chassis 300 serving as a camera main body frame, and an imaging unit 400 are fixed to the mirror box 5 in order from the subject side. In particular, the imaging unit 400 is attached with a removable photographing lens. The image pickup surface of the image pickup device 33 is adjusted and fixed so that the image pickup surface of the image pickup element 33 is parallel to a predetermined distance on the reference mounting surface of the mount 2.

  First, 420 is a resin or metal low-pass filter holding member having a frame portion that surrounds the optical low-pass filter 410 and an arm portion for mounting and holding left and right, as shown in FIG. A storage portion for storing the piezoelectric element 430 is provided on the side, and one end of the piezoelectric element 430 is fixed by adhesion or the like.

  Further, a housing portion for housing a biasing member 440 having a spring property is provided on the opposite side of the frame portion, and is configured to bias the optical low-pass filter 410 in the direction of the piezoelectric element 430.

  That is, with respect to the low-pass filter holding member 420, the optical low-pass filter 410 is disposed so as to be sandwiched between the piezoelectric element 430 and the biasing member 440 in substantially the same in-plane direction, and the biasing member 440 moves the optical low-pass filter 410. Follows the expansion / contraction movement of the piezoelectric element 430.

  As long as the urging member 440 is an elastic body, a plate spring or a coil spring formed of metal may be used, or a polymer such as rubber or plastic may be used. In this embodiment, the urging member 440 is provided as a separate member. However, by providing the low-pass filter holding member 420 with a spring property, the movement of the optical low-pass filter 410 follows the expansion and contraction movement of the piezoelectric element 430. You may hold as you do.

  Further, a frame-shaped elastic member 450 is interposed between the four sides of the outer periphery of the optical low-pass filter 410 and the low-pass filter holding member 420. The rigidity of the frame-like cross section of the elastic member 450 is changed between the cross section B-B of the arm part orthogonal to the expansion / contraction direction of the piezoelectric element 430 and the cross section AA of the arm part parallel to the expansion / contraction direction of the piezoelectric element 430. In other words, the elastic member 450 is weak in the direction allowing the swing of the optical low-pass filter 410 following the expansion and contraction of the piezoelectric element 430, and on the plane of the optical low-pass filter 410 having an angle with respect to the expansion and contraction of the piezoelectric element 430. On the other hand, it is integrally formed so as to increase the rigidity in the direction of falling.

  Furthermore, the four sides around the optical low-pass filter 410 are hermetically sealed with the piezoelectric element 430 and the elastic member 450 with respect to the low-pass filter holding member 420.

  Here, in this embodiment, the piezoelectric element 430 uses a stacked piezoelectric element in which piezoelectric bodies and internal electrodes are alternately stacked. Internal electrodes are arranged between the piezoelectric bodies. Since these internal electrodes are made of a metal material, a predetermined voltage is applied to each piezoelectric body through the internal electrodes, and the piezoelectric bodies are displaced by the inverse piezoelectric effect. Has the effect of causing it. In this embodiment, a d33 type stacked piezoelectric element that applies a voltage in the stacking direction of the piezoelectric body is adopted, but there are various forms of the piezoelectric element, and the displacement in the horizontal direction of the optical low-pass filter is changed. Any piezoelectric element may be used as long as it occurs.

  The larger the cross-sectional area of the piezoelectric element, the larger the output can be obtained, but the cross-sectional shape of the piezoelectric element in this example is equal to or less than the optical low-pass filter thickness in the optical axis direction. By making the length in the direction perpendicular to the optical axis direction and perpendicular to the swinging direction longer, the camera is prevented from being enlarged in the optical axis direction while obtaining a larger output. In addition, since the cross-sectional shape of the piezoelectric element is configured as described above, an allowable buckling stress against rotation in a plane perpendicular to the optical axis of the piezoelectric element 430 is increased, so that the optical low-pass filter 410 is placed on the optical axis. It is possible to prevent the piezoelectric element from buckling even if it vibrates with a rotational component in a vertical plane.

  In this embodiment, the optical low-pass filter 410 and the piezoelectric element 430 are in direct contact with each other, but a configuration in which a spacer is sandwiched therebetween may be used. In this embodiment, the piezoelectric element 430 is accommodated in the low-pass filter holding member 420. However, the present invention is not limited to this, and the present invention can be applied even if the piezoelectric element accommodating portion is configured as a separate member. is there.

  The piezoelectric element 430 is held in a direction (camera top-down direction) in which the expansion / contraction direction by voltage application is orthogonal to the optical axis. The piezoelectric element 430 may be bonded to the low-pass filter holding member 420, but is not bonded to the optical low-pass filter 410. One end of the optical low-pass filter 410 is in contact with the piezoelectric element 430, and the opposite end is in contact with the biasing member 440. The biasing member 440 biases the optical low-pass filter 410 with respect to the piezoelectric element 430 in a direction substantially perpendicular to the optical axis so that the movement of the optical low-pass filter 410 follows the expansion and contraction movement of the piezoelectric element 430. As long as the urging member 440 is an elastic body, a plate spring or a coil spring formed of metal may be used, or a polymer such as rubber or plastic may be used. In this embodiment, the urging member 440 is provided as a separate member. However, by providing the low-pass filter holding member 420 with a spring property, the movement of the optical low-pass filter 410 follows the expansion and contraction movement of the piezoelectric element 430. You may hold as you do.

  Next, 460 is a plate-like regulating member that regulates the optical low-pass filter 410 so as to be sandwiched between the low-pass filter holding member 420 in a direction perpendicular to the optical plane direction, and is fixed so that the periphery is hooked on the low-pass filter holding member 420. Is done.

  Accordingly, the optical low-pass filter 410 is restricted in movement in the optical axis direction between the optical member regulating member 460 and the low-pass filter holding member 420, and prevents buckling destruction due to the piezoelectric element 430 falling in the optical axis direction. Is possible. The optical member regulating member 460 covers the outer peripheral portion of the optical low-pass filter 410, prevents the photographing light flux from entering the image sensor from the outer peripheral portion of the optical low-pass filter 410, and reflects the outer peripheral portion of the optical low-pass filter 410. It prevents ghosts caused by light. Accordingly, the outer peripheral dimension of the optical low-pass filter can be brought close to the effective light beam (the light receiving surface of the image sensor 33). Therefore, the cost can be reduced by making the expensive optical low-pass filter 410 as small as possible. It becomes possible.

  As described above, the optical low-pass filter 410 is swingably held so as to be sandwiched between the piezoelectric element 430 and the biasing member 440 with respect to the low-pass filter holding member 420, and the outer peripheral portion of the optical low-pass filter 410 is frame-shaped elastic member 450. A low-pass filter holding unit 470 that is hermetically sealed so as to be regulated by a regulating member 460 in a direction orthogonal to the optical surface of the optical low-pass filter 410 is configured.

Reference numeral 510 denotes a plate-shaped image sensor holding member that has a rectangular opening and fixes the image sensor 33 so that the image sensor 33 is exposed in the opening, and an arm portion for fixing the screw to the mirror box 5 around it. Own three. The image sensor holding member 510 and the image sensor 33 constitute an image sensor holding unit 500.

  The low-pass filter holding member 420 of the low-pass filter holding unit 470 is provided with a step screw 530 so that the arm of the low-pass filter holding member 420 is connected to the imaging element holding member 510 of the imaging element holding unit 500 so as to sandwich the rubber sheet 520 having elasticity. The above-described imaging unit 400 is combined. The rubber sheet 520 is integrally formed with an annular arm portion that points the two step screws 530 facing the frame portion. One of the frame portions is in close contact with the image sensor 33 and the other is the frame of the low-pass filter holding member 420. Close contact with the part.

  Accordingly, the gap between the low-pass filter holding member 420 and the image sensor 33 is sealed with the rubber sheet 520, and the gap between the optical low-pass filter 410 and the low-pass filter holding member 420 is sealed with the piezoelectric element 430 and the elastic member 450. The space between the low-pass filter 410 and the image sensor 33 is a sealed space from which dust or the like does not enter.

  Further, even when the piezoelectric element 430 is in a vibration state, the vibration of the low-pass filter holding unit 470 has a floating support structure due to the elasticity of the rubber sheet 520, and is not easily transmitted to the imaging element 33.

  Next, the operation will be described.

  When a predetermined periodic voltage is applied to the piezoelectric element 430 housed in the low-pass filter holding member 420, the piezoelectric element 430 vibrates in the direction perpendicular to the optical axis (the camera top-to-bottom direction). The optical low-pass filter 410 is disposed so as to be sandwiched between the piezoelectric element 430 and the biasing member 440 in substantially the same in-plane direction. Therefore, since the optical low-pass filter 410 and the piezoelectric element 430 are held in close contact with each other, the vibration of the piezoelectric element 430 causes the optical low-pass filter 410 to be in a direction substantially parallel to the vibration direction of the piezoelectric element 430 and perpendicular to the optical axis ( It is vibrated in the direction of the camera.

  As described above, the gap between the low-pass filter holding member 420 and the imaging element 33 is sealed with the rubber sheet 520, and the gap between the optical low-pass filter 410 and the low-pass filter holding member 420 is sealed with the piezoelectric element 430 and the elastic member 450. The space between the optical low-pass filter 410 and the image sensor 33 is a sealed space from which dust or the like does not enter, and the vibration of the low-pass filter holding unit 470 is absorbed by the rubber sheet 520 and hardly transmitted to the image sensor 33. ing. With these configurations, even if the piezoelectric element 430 vibrates, the imaging element 33 hardly vibrates, and only the optical low-pass filter 410 vibrates. Therefore, the mass of the object to be vibrated can be reduced, and the optical element can be obtained with less energy The low-pass filter 410 can be vibrated. Furthermore, since the vibration of the optical low-pass filter 410 is hardly transmitted to the image sensor 33, it is possible to prevent damage such as adhesion peeling of the image sensor 33. Conversely, when an impact is applied to the camera, the impact is hardly transmitted to the piezoelectric element 430, so that the piezoelectric element 430 can be prevented from being damaged by the impact.

  In addition, by maintaining substantially confidentiality between the image sensor and the optical low-pass filter, foreign matter can be prevented from entering the space from the outside. A gap is not generated during vibration, and foreign matter is prevented from entering from the outside.

  As described above, since the optical low-pass filter 410 and the piezoelectric element 430 are not coupled, the piezoelectric element 430 is not pulled by the optical low-pass filter 410 even when a periodic voltage is applied to the piezoelectric element 430 to expand and contract. Therefore, even if a high frequency voltage in the ultrasonic range is applied to the piezoelectric element 430, an excessive tensile stress is not applied to the piezoelectric element 430, and it is possible to prevent damage such as peeling at the laminated portion. .

  In the above-described embodiment, the optical low-pass filter 410 is illustrated as an optical component to be vibrated. However, the present invention is not limited to this, and other optical components can be applied.

  Next, an operation for removing dust and the like attached to the surface of the optical low-pass filter 410 in this embodiment will be described with reference to the flowchart of FIG.

  First, it starts in step S9, and in step S10, when the power is turned on, it is determined whether or not the setting of the sweep operation of the camera is enabled. If the setting of the sweep operation is not enabled, the process proceeds to step S14. If it is valid, the process proceeds to step S11. Here, the sweep operation refers to an operation for removing dust on the optical low-pass filter 410.

  In step S11, the aperture value of the lens attached to the camera is acquired. In step S12, the vibration mode is determined. Details of the determination method will be described later.

  In step S13, the optical low-pass filter 410 is vibrated in the vibration mode determined in step S12. At this time, the optical low-pass filter 410 is vibrated by vibrating the piezoelectric element 430 in accordance with an instruction from the microcomputer 100.

  In step S14, when the release button 7 is pressed halfway, the brightness of the subject is measured using the photometric sensor 37, and the shutter time and aperture value are calculated. Next, the AF sensor 31 is used to detect the defocus amount of the subject, communication is performed with the lens unit using the communication terminals 21 on the camera side and the lens unit side, and the AF drive circuit 202 is used under lens system control. The photographic lens 200 is driven to the in-focus position.

In step S15, the lens information attached to the camera and the aperture value calculated in step S14 are acquired. In step S16, the vibration mode is determined. In step S17, the optical low-pass filter 410 is used in the vibration mode determined in step S16. Vibrate. At this time, the optical low-pass filter 410 is vibrated by vibrating the piezoelectric element 430 in accordance with an instruction from the microcomputer 100.

  When the release button 7 is completely pressed in step S18, SW2 is turned on. In step S19, the quick return mirror 6 is in the mirror-up state, and the aperture calculated by the lens control circuit 201 via the aperture drive circuit 203 is calculated. The lens aperture is controlled to the value. Thereafter, exposure is started and a specific frequency component is cut by the optical low-pass filter 410, and then an image signal is captured by the image sensor 33. The taken analog signal is converted into a digital signal by the A / D converter 36, and the video signal processing circuit 104 performs image processing based on the set ISO value. The image data that has undergone image processing is temporarily written in the buffer memory 37 via the memory controller 38 and then written in the external memory 39 or written on an external recording medium via the interface 40, step S20. It will end.

  When the photographer operates the cleaning mode operation member 44, the camera body 101 is shifted to the cleaning mode state in response to the instruction to start the cleaning mode. The cleaning mode operation member 44 is an operation member for instructing the transition to the cleaning mode. For example, the cleaning mode operation member 44 may include a mechanical button, a switch, or the like, or a cursor from a menu displayed on the external liquid crystal display device 9. It may be set using a key or an instruction button.

  When this operation is performed, the same operation as step S11 to step S13 is performed.

  As described above, the piezoelectric element 430 expands and contracts according to the applied voltage. When the piezoelectric element extends, the optical low-pass filter 410 is pushed by the piezoelectric element 430 and moves in the plane horizontal direction perpendicular to the optical axis, and the urging member 440 contracts by the amount of movement. When the piezoelectric element 430 contracts, the optical low-pass filter 410 is urged against the piezoelectric element 430 by the urging member 440, and thus moves following the contraction movement of the piezoelectric element 430. When a periodic voltage is applied to the piezoelectric element 430, the above movement is repeated, and the optical low-pass filter 410 follows the periodic expansion and contraction of the piezoelectric element 430 and vibrates in the plane horizontal direction perpendicular to the optical axis.

  Next, the vibration mode determination in steps S12 and S16 will be described with reference to FIG.

  When the aperture value is up to F5.6, the dust attached to the image sensor is hardly reflected in the captured image, so the energizing time is shortened, the frequency and the operating frequency are small, and the power consumption is low. Set the state.

  In addition, when the aperture value is from F5.6 to F8, the dust attached to the image sensor is relatively easy to be captured as the photographed image. Sets the state of acceleration. In this case, power consumption is greater than in the above case.

  Furthermore, when the aperture value is F8 or more, the dust attached to the image sensor is very easy to be captured as a captured image, so the energization time is long, and the operating frequency is the maximum amplitude and acceleration as the resonance frequency. Set the frequency to be Power consumption is maximized.

  The energization time and frequency, and this combination are not limited to this.

  Next, the mechanism by which foreign matter on the optical low-pass filter surface is removed by the vibration of the optical low-pass filter 410 will be described using equations (1) and (2).

  The foreign matter is attached to the optical low-pass filter by a force such as a liquid bridging force, van der Waals force, or electrostatic force. As shown in the figure, this adhesion force acts in the vertical direction with respect to the optical low-pass filter surface. As shown in Expression (1), when the optical low-pass filter vibrates, an inertial force F proportional to the vibration acceleration α and the mass of the foreign matter is applied to the foreign matter.

F = mα Formula (1)
At this time, since the vibration direction of the optical low-pass filter is the horizontal direction, the inertia force F acts in a direction perpendicular to the adhesion force N. When the inertial force F applied to the foreign matter is larger than the maximum static friction force necessary for the foreign matter to move, the foreign matter moves relative to the optical low-pass filter and is removed from the optical low-pass filter surface. The maximum static frictional force for moving the foreign matter is expressed by the product of the adhesion force N between the foreign matter and the optical low-pass filter and the static friction coefficient μ. It is represented by

F = mα ≧ μN (N) (2)
The static friction coefficient μ depends on the foreign material, the material of the optical low-pass filter, the surface condition, environmental conditions such as temperature and humidity, etc. For example, the static friction coefficient μ between glass and plastic is generally about 0.3. ing.

  That is, by vibrating the optical low-pass filter in the horizontal direction and applying an inertial force F in the vertical direction to the adhesive force N, the foreign matter can be moved by a force that is μ times (approximately 0.3 times) the adhesive force N. This makes it possible to remove foreign matter with less energy.

  By applying a periodic voltage to the piezoelectric element in this way, the optical low-pass filter vibrates, and foreign matter adhering to the optical low-pass filter surface is removed.

  As described above, according to the present embodiment, the foreign matter adhering to the surface of the optical low-pass filter in the vicinity of the image sensor is more efficiently removed by the cleaning operation, and unnecessary power consumption is eliminated. It is possible to provide an imaging apparatus capable of performing the above and a control method thereof.

It is the external appearance perspective view seen from the front of the digital single-lens reflex camera which is embodiment of this invention. It is the external appearance perspective view seen from the back side of the digital single-lens reflex camera which is embodiment of this invention. 1 is a block diagram showing an electrical configuration of a digital single-lens reflex camera according to an embodiment of the present invention. It is a disassembled perspective view which shows schematic structure inside a camera for showing the low-pass filter and the holding structure around an image sensor. It is sectional drawing which shows the low-pass filter holding | maintenance unit 470 and its cross section AA. 4 is an exploded perspective view for illustrating a holding structure for a low-pass filter holding unit 470, a rubber sheet 520, and an image sensor holding unit 500. FIG. It is a perspective view which shows the detailed structure around a low-pass filter and an image pick-up element. 6 is a front view showing a part of the constituent members of a low-pass filter holding unit 470. FIG. It is a component detail drawing of the elastic member 450. It is a component detailed view of the rubber sheet 520. It is a flowchart which shows the flow of a process of automatic setting of a vibration mode. It is the figure which defined the vibration mode according to the stage with the aperture value of the lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera body 1a Grip part 2 Mount 4 Lens lock release button 5 Mirror box 6 Quick return mirror 7 Shutter button 8 Main dial 9 Liquid crystal display part 10 Top surface operation mode setting button 11 Strobe unit 12 Shoe groove 13 Flash contact 14 Shooting mode setting dial DESCRIPTION OF SYMBOLS 15 External terminal cover 16 Video signal output jack 17 USB output connector 18 Finder eyepiece window 19 Liquid crystal display part 20 Sub operation dial 21 Mount contact 32 Shutter unit 33 Image sensor 300 Main body chassis 400 Imaging unit 410 Optical low-pass filter 420 Low-pass filter holding Member 430 Piezoelectric element 440 Energizing member 450 Elastic member 460 Restricting member 500 Imaging element holding unit 510 Imaging element holding member 520 Mushito 520a rubber sheet frame portion 520b rubber sheet arms 530 stages bis

Claims (2)

A mount part to which the taking lens can be attached and detached;
Detecting means for detecting the mounting and aperture value of the photographing lens;
Imaging means for converting an optical image of a subject into an electrical signal;
An optical element disposed in front of the imaging means;
In an imaging apparatus having a driving unit that vibrates the optical element,
Setting means for setting a vibration mode of the drive means based on the state detected by the detection means;
An image pickup apparatus that drives the drive unit according to the set vibration mode.   The imaging apparatus according to claim 1, wherein the setting unit sets, as the vibration mode, one of a driving time and a driving frequency of the driving unit, or a combination thereof.

Images