JP2008026531A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the damage or the like of an imaging device or the like due to the transmission of vibration of a vibration means for removing a foreign matter adhering to the vicinity of the imaging device of a digital camera. <P>SOLUTION: A holding member (420) holding an optical member to be vibrated and an imaging device unit (500) including the imaging device are fixed independently on a mirror box (5) or a main body chassis (300) that is a member relatively larger than them. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, and more particularly to a technique for removing foreign matters such as dust adhering to an optical member disposed on a photographing optical axis.

  In an imaging device such as a digital camera that captures an image by converting an image signal into an electrical signal, the imaging light beam is received by an imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (C-MOS), and the imaging element. The output photoelectric conversion signal is converted into image data and recorded on a recording medium such as a memory card. In such an image pickup apparatus, an optical low-pass filter or an infrared cut filter is disposed on the object side of the image pickup device, and when foreign matter such as dust adheres to the cover glass of the image pickup device or the surface of these filters, the attached portion Becomes a black dot and appears in the photographed image, and the image looks worse.

  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 stick to optical 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, as disclosed in Patent Document 1, a dustproof curtain that transmits a photographic light beam is provided on the subject side of the image sensor, and this is vibrated by a piezoelectric element, thereby removing foreign matters such as dust attached to the surface of the dustproof curtain. Proposed.
JP 2003-319222 A

  According to the above prior art, in order to remove the foreign matter adhering to the surface of the dust screen, a voltage is applied to the piezoelectric element joined to the dust screen, and the dust screen is displaced in the optical axis direction by driving this piezoelectric device. The curtain vibration is generated.

  However, when the vibration of a vibrating member such as a dust screen or a vibrating member such as a piezoelectric element is transmitted to the imaging element, the imaging element is damaged, the joint with the electronic member around the imaging element is damaged, or the imaging element Looseness of the fixed part may occur.

  Therefore, when the optical member is vibrated by the vibration member, it is possible to vibrate efficiently so that the vibration is not hindered, and it is necessary to hold the optical member so that the vibration is not transmitted to the image sensor. There is.

  The present invention has been made in view of the above-described problems, and damage to an imaging element or the like due to vibration transmission, such as a vibration member for removing foreign matter attached to an optical member disposed on a photographing optical axis. An object of the present invention is to provide an imaging device that alleviates the above.

  In order to achieve the above object, an image pickup apparatus according to claim 1 includes an image pickup device unit including an image pickup device that converts an optical image of a subject into an electrical signal, and a front surface of the image pickup device on a photographing optical axis. An optical member disposed; an excitation unit that applies vibration to the optical member; an optical member holding member that holds the optical member; a base member; and a control unit that controls vibration of the excitation unit. The optical imaging element unit and the optical member holding member are fixed independently to the base member, which is a relatively larger member.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to ease damage to an image pick-up element etc. by the transmission of a vibration resulting from vibrating an optical element.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  1 and 2 are views showing an external appearance of a digital single-lens reflex camera according to the present embodiment. Specifically, FIG. 1 is a perspective view seen from the front side of the camera, showing a state in which the taking lens unit is removed, and FIG. 2 is a perspective view seen from the back side of the camera.

  In FIG. 1, reference numeral 1 denotes a camera body, which is provided with a grip portion 1a that protrudes forward so that a user can easily hold the camera stably during shooting. Reference numeral 2 denotes a mount unit that fixes a detachable photographic lens unit (not shown) to the camera body. The mount contact 21 has a function of supplying control power, a status signal, a data signal, and the like between the camera body and the photographing lens unit and supplying power to the photographing lens unit. 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 disposed in the camera housing, and the photographic light flux that has passed through the photographic lens is guided here. A quick return mirror 6 is disposed inside the mirror box 5. The quick return mirror 6 is held at an angle of 45 ° with respect to the photographic optical axis in order to guide the photographic light flux toward the pentaprism 22 (see FIG. 3), and the image sensor 33 (see FIG. 3). Therefore, it is possible to take a state of being held at a position retracted from the photographing light flux.

  On the grip side of the upper part of the camera, a shutter button 7 as a start switch for 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 an upper surface operation of the shooting system A mode setting button 10 is arranged. Some of the operation results of these operation members are displayed on the LCD display panel 9.

  The shutter button 7 is configured such that SW1 (7a, described later) is turned on in the first stroke, and SW2 (7b, described later) is turned on in the second stroke.

  The top operation mode setting button 10 is used for setting whether the shutter button 7 is pressed once for continuous shooting or shooting for only one frame, setting for the self-shooting mode, and the like. The setting status is displayed on the panel 9.

  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 external terminal lid 15 that can be opened and closed is provided on the side opposite to the grip. Inside the external terminal lid 15, a video signal output jack 16 and a USB output connector are provided as external interfaces. 17 is stored.

  In FIG. 2, a viewfinder eyepiece window 18 is provided on the back side of the camera, and a color liquid crystal monitor 19 capable of displaying an image is provided near the center of the back side. The sub operation dial 20 arranged beside the color liquid crystal monitor 19 plays an auxiliary role of the function of the main operation dial 8. For example, in the AE mode of the camera, the exposure correction amount for the appropriate exposure value calculated by the automatic exposure device is set. 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 to select display of a captured image displayed on the color liquid crystal monitor 19.

  Reference numeral 43 denotes a main switch for starting or stopping the operation of the camera.

  Reference numeral 44 denotes a cleaning instruction operation member for operating the cleaning mode, which is for instructing an operation for removing dust adhering to the low-pass filter. Details will be described later.

  FIG. 3 is a block diagram showing the main electrical configuration of the digital single-lens reflex camera according to the present embodiment. In addition, the part which is common in the above-mentioned drawing is shown with the same symbol.

  Reference numeral 100 denotes a microcomputer central processing unit (hereinafter referred to as MPU) built in the camera body. The MPU 100 controls the operation of the camera, and executes various processes and instructions for each element.

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

  Connected to the MPU 100 are 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, and a photometric circuit 106. Further, the LCD drive circuit 107, the battery check circuit 108, the time measurement circuit 109, the power supply circuit 110, and the piezoelectric element drive circuit 111 are also connected. These circuits operate under the control of the MPU.

  Further, the MPU 100 communicates with the lens control circuit 201 disposed in the photographing lens unit via the mount contact 21. The mount contact 21 also has a function of transmitting a signal to the MPU 100 when the photographing lens unit is connected. Thereby, the lens control circuit 201 can communicate with the MPU 100 and drive the photographing lens 200 and the diaphragm 204 in the photographing lens unit via the AF driving circuit 202 and the diaphragm driving circuit 203. Become.

  In the present embodiment, a single photographing lens is shown for the sake of convenience, but in actuality, it is composed of a large number of lens groups.

  The AF drive circuit 202 is configured by, for example, a stepping motor, and adjusts the imaging light flux to be focused on the image sensor 33 by changing the focus lens position in the imaging lens 200 under the control of the lens control circuit 201. Reference numeral 203 denotes an aperture drive circuit, which is configured by, for example, an auto iris or the like, and is configured to change an aperture 204 by a lens control circuit 201 to obtain an optical aperture value.

  The main mirror 6 guides the photographic light beam passing through the photographic lens 200 to the pentaprism 22 and transmits part of the light to the sub mirror 30. The sub mirror 30 guides the transmitted photographic light beam to the focus detection sensor unit 31.

  The mirror driving circuit 101 is for driving the mirror 6 to a position where the subject image can be observed by the viewfinder and a position where the mirror 6 is retracted from the photographing light flux. At the same time, the sub mirror 30 is driven to a position for guiding the photographing light flux to the focus detection sensor unit 31 and a position for retracting from the photographing light flux. Specifically, it is composed of, for example, a DC motor and a gear train.

  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. The signal output from the focus detection sensor unit 31 is supplied to the focus detection circuit 102, converted into a subject image signal, and then transmitted to the MPU 100. The MPU 100 performs focus detection calculation by the phase difference detection method based on the subject image signal. Then, the defocus amount and the defocus direction are obtained, and based on this, the focus lens in the photographing lens 200 is driven to the in-focus position via the lens control circuit 201 and the AF drive circuit 202.

  Reference numeral 22 denotes a pentaprism, which is an optical member that converts and reflects the photographing light beam reflected by the main mirror 6 into an erect image. The user can observe the subject image from the viewfinder eyepiece window 18 through the viewfinder optical system.

  The pentaprism 22 guides part of the photographing light flux to the photometric sensor 37. The photometric circuit 106 obtains the output of the photometric sensor 37, converts it into a luminance signal of each area on the observation surface, and outputs it to the MPU 100. The MPU 100 calculates an exposure value from the obtained luminance signal.

  Reference numeral 32 denotes a mechanical focal plane shutter that blocks a photographing light beam when a user observes a subject image with a viewfinder. Further, at the time of imaging, a desired exposure time is obtained according to the time difference between travel of a front blade group and a rear blade group (not shown) according to a release signal. The focal plane shutter 32 is controlled by the shutter drive circuit 103 that has received a command from the MPU 100.

  Reference numeral 33 denotes an image pickup device, which uses a CMOS as an image pickup 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.

  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.

  An optical low-pass filter 410 is formed by laminating and laminating a plurality of birefringent plates and phase plates made of quartz, and further laminating an infrared cut filter.

  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 104 denotes a video signal processing circuit, which performs overall hardware image processing such as gamma / knee processing, filter processing, and monitor display information synthesis processing on digitized image data. The image data for monitor display from the video signal processing circuit 104 is displayed on the color liquid crystal monitor 19 via the color liquid crystal drive circuit 112.

  Further, the video signal processing circuit 104 can also store image data in the buffer memory 37 through the memory controller 38 in accordance with an instruction from the MPU 100. Further, the video signal processing circuit 104 has a function of performing image data compression processing such as JPEG. When continuous shooting is performed, such as continuous shooting, image data can be temporarily stored in the buffer memory 37 and unprocessed image data can be sequentially read out through the memory controller 38. Thus, the video signal processing circuit 104 can sequentially perform image processing and compression processing regardless of the speed of the image data input from the A / D converter 36.

  The memory controller 38 stores image data input 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. It also has a function of outputting image data from the external interface 40. The memory 39 is a flash memory that can be attached to and detached from the camera body.

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

  Reference numeral 107 denotes an LCD drive circuit that drives the LCD display panel 9 and the in-finder liquid crystal display device 41 in accordance with instructions from the MPU 100.

  A battery check circuit 108 performs a battery check for a predetermined time in accordance with a signal from the MPU 100 and sends the detection output to the MPU 100. A power supply unit 42 supplies necessary power to each element of the camera.

  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.

  Next, the detailed configuration of each unit will be described below with reference to FIGS.

  FIG. 4 is an exploded perspective view showing a schematic configuration inside the camera for showing a low-pass filter and a holding structure around the image sensor.

  A shutter unit 32 is attached to the mirror box 5 in order from the subject side. Then, a low-pass filter unit 470 described later is attached to the mirror box 5 with screws. Further, an image sensor unit 500 described later is screwed to the mirror box 5 independently of the low-pass filter unit 470, that is, without being fastened to each other. The elastic rubber sheet 520 is sandwiched so as to seal the space between the low-pass filter unit 470 and the image sensor unit 500. Specifically, as will be described later, the rubber sheet 520 is made of a very soft material and is bonded to the low-pass filter unit 470 and the image sensor unit 500, for example, with a double-sided tape. The image pickup device unit 500 is adjusted and fixed so that the image pickup surface of the image pickup device 33 is parallel to a predetermined distance and parallel to the mounting surface of the mount 2 serving as a reference to which the photographing lens unit is attached.

  FIG. 5 is a front view showing components of the low-pass filter unit 470.

  Reference numeral 420 denotes a resin or metal low-pass filter holding member having a frame part 420a that surrounds the periphery of the optical low-pass filter 410 and an arm part 420b that extends to the left and right. A storage part 421 for storing the piezoelectric element 430 is provided on one side of the frame part 420a, and one end surfaces of the frame part 420a and the piezoelectric element 430 are fixed by adhesion or the like.

  A storage portion 422 for storing a biasing member 440 having a spring property is provided on the side of the frame portion 420 a that faces the side having the storage portion 421, and the optical low-pass filter 410 is arranged in the direction of the piezoelectric element 430. It is comprised so that it may bias.

  That is, the optical low-pass filter 410 is arranged so that the piezoelectric element 430 and the biasing member 440 are sandwiched in the same plane in the low-pass filter holding member 420. With this arrangement, the optical low-pass filter 410 follows the expansion and contraction motion 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, the movement of the optical low-pass filter 410 follows the expansion and contraction of the piezoelectric element 430 by providing the low-pass filter holding member 420 with a spring property. You may make it do.

  Further, a frame-shaped elastic member 450 as shown in FIG. 6 is interposed between the four sides surrounding the optical low-pass filter 410 and the low-pass filter holding member 420. That is, the elastic member 450 is arranged so as to be in contact with and sandwiched between the low-pass filter holding member 420 and the optical low-pass filter 410 in the thickness direction of the optical low-pass filter 410.

  FIG. 6 is a detailed view of the elastic member 450. The elastic member 450 includes 450a which is an arm portion in the expansion / contraction direction of the piezoelectric element 430 and 450b which is an arm portion in the orthogonal direction. Here, the arm portion 450a and the arm portion 450b are configured to have different rigidity. That is, the elastic member 450 makes the rigidity of the arm part 450b subjected to the expansion / contraction action smaller than the rigidity of the arm part 450a in order to allow the optical low-pass filter 410 to swing following the expansion / contraction of the piezoelectric element 430. . Specifically, the cross section AA of the arm portion 450a is configured by a rectangle as shown in the figure, whereas the cross section BB of the arm portion 450b is configured by a shape partially cut out from the rectangle. Has been.

  The structure which changes the rigidity of the arm part 450a and the arm part 450b is not restricted to this, For example, you may make it integrate the arm part comprised by the different member by two-color molding etc. FIG.

  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.

  In the present embodiment, the piezoelectric element 430 is a stacked piezoelectric element in which generally known piezoelectric bodies and internal electrodes are alternately stacked. More specifically, a d33 type stacked piezoelectric element that applies a voltage in the stacking direction of the piezoelectric bodies is employed. Accordingly, a larger amplitude (displacement) can be obtained in the stacking direction. That is, the optical low-pass filter 410 can be greatly displaced in the vibration direction. In addition, there are various types of piezoelectric elements, and any piezoelectric element can be used as long as it causes displacement in the horizontal direction of the optical low-pass filter, that is, in the direction perpendicular to the optical axis. The shape and the like of the piezoelectric element will be described later with reference to FIG.

  In the present 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. By sandwiching the spacer, the piezoelectric element 430 only needs to apply vibration to the spacer, so that it is possible to relax the constraints on the layout.

  As described above, the piezoelectric element 430 is held in a direction (camera top-and-bottom direction) in which the expansion and contraction direction due to voltage application is orthogonal to the optical axis. Here, although the piezoelectric element 430 is bonded and fixed to the low-pass filter holding member 420, it is only in contact with the optical low-pass filter 410 without being bonded. That is, the vibration surface of the piezoelectric element 430 with respect to the optical low-pass filter 410 is not fixed to the optical low-pass filter 410.

  Since the optical low-pass filter 410 is supported by the elastic member 450, a predetermined amount is allowed not only for the expansion / contraction direction of the piezoelectric element 430 but also for the movement in the photographing optical axis direction. That is, the optical low-pass filter 410 is configured to be allowed to have a certain degree of inclination with respect to a plane orthogonal to the photographing optical axis by receiving the vibration of the piezoelectric element 430. By configuring in this way, the foreign matter adhering to the optical low-pass filter can be accelerated in the direction of the photographing optical axis, which is more preferable for removing the foreign matter. However, when the inclination of the optical low-pass filter 410 with respect to the plane orthogonal to the photographing optical axis is allowed, if the piezoelectric element 430 and the optical low-pass filter 410 are bonded, a shear stress is generated in the piezoelectric element 430. In particular, when a laminated piezoelectric element is used as in the present embodiment, it is not preferable because the piezoelectric element is destroyed by such shear stress.

  With respect to such a problem, if the vibration surface of the piezoelectric element 430 with respect to the optical low-pass filter is not adhered to the optical low-pass filter 410, that is, only touches, the optical low-pass filter 410 has a plane perpendicular to the photographing optical axis. Even if it is tilted, no shear stress is generated in the piezoelectric element 430. This is because when the optical low-pass filter 410 is tilted in this way, the vibration surface of the piezoelectric element 430 and the contacted surface of the optical low-pass filter 410 are relatively displaced, and the piezoelectric element 430 rotates directly. It is because it does not receive power.

  On the other hand, when the vibration surface of the piezoelectric element 430 and the optical low-pass filter 410 are not bonded, there arises a problem that the followability of the optical low-pass filter is deteriorated with respect to the vibration of the piezoelectric element. As described above, this problem is addressed by arranging the optical low-pass filter 410 so as to be sandwiched between the piezoelectric element 430 and the biasing member 440 in the same plane. That is, by biasing the optical low-pass filter 410 with a spring or the like from the opposite side, the optical low-pass filter 410 is always in contact with the piezoelectric element 430 even when the piezoelectric element 430 is driven in the contraction direction.

  With this configuration, good followability to vibration of the optical low-pass filter 410 is ensured while avoiding destruction of the piezoelectric element 430 due to generation of shear stress.

  FIG. 7 is an exploded perspective view for further explaining the components constituting the low-pass filter unit 470 and the image sensor unit 500 described with reference to FIGS. 4 and 5.

  Reference numeral 500 denotes an image sensor unit, which includes at least the image sensor 33 and an image sensor holding member 510. Reference numeral 470 denotes a low-pass filter unit, which includes at least an optical low-pass filter 410, a low-pass filter holding member 420, a piezoelectric element 430, a biasing member 440, an elastic member 450, and a regulating member 460.

  The restricting member 460 sandwiches the optical low-pass filter 410 with the low-pass filter holding member 420 at a predetermined interval in the photographing optical axis direction, thereby restricting the movement of the optical low-pass filter 410 in the photographing optical axis direction. is doing. By restricting in this way, the optical low-pass filter 410 is prevented from tilting more than a predetermined angle with respect to a plane orthogonal to the photographing optical axis.

  The restricting member 460 has an opening that restricts the opening of the optical low-pass filter 410, and shields the imaging light flux that enters the area other than the opening. Thereby, the photographing light flux is prevented from entering the image sensor from the outer peripheral portion of the optical low-pass filter 410, and the occurrence of ghost due to the reflected light is prevented.

  Reference numeral 520 denotes a rubber sheet having elasticity. The rubber sheet 520 does not belong to the low-pass filter unit 470 or the imaging element unit 500, and as described above, seals the space between both units and prevents the entry of dust from the outside. Take on. At the same time, since it is formed of a very soft material, it also plays a role of absorbing vibration of the low-pass filter unit 470 and not transmitting it to the image sensor unit 500.

  In the present embodiment, 520 is described as a rubber sheet. However, the above-described rigid member is a member having a sealing property to prevent intrusion of foreign matter and a vibration absorption property that does not transmit vibration of the optical low-pass filter 410 to the image sensor 33. It is not limited to this as long as it satisfies the relationship. For example, a sponge-like double-sided tape or gel sheet having a certain thickness can be applied.

  FIG. 8A is a front view for explaining the relative relationship between the piezoelectric element 430 and the optical low-pass filter 410 and the relationship between the generated forces, and FIG. 8B is a side view of the same.

  In the present embodiment, of the two sides orthogonal to the stacking direction (vibration direction) of the piezoelectric elements, the length perpendicular to the optical axis direction shown in FIG. 8A is L, and the light shown in FIG. The length in the axial direction is T2. Since other components (for example, the shutter unit 32 and the image sensor 33) are arranged close to each other in the optical axis direction as described above, T2 is optical in order to avoid an increase in the size of the camera. It is preferable that the thickness is equal to or smaller than the thickness T1 of the low-pass filter 410. Further, L is a length longer than T1, and is a corresponding length for obtaining a driving force necessary to vibrate the optical low-pass filter 410. As described with reference to FIG. 5, the storage portion 421 of the low-pass filter holding member 420 is provided in the direction orthogonal to the optical axis, and the length of the storage portion 421 falls within the width of the optical low-pass filter 410. This is because it is possible to make space relatively easily in the range. Therefore, by defining the two sides in this way, the driving force for vibration can be obtained in proportion to the piezoelectric body area of L × T2.

  Further, by increasing L as described above, even if a large moment is generated by the optical low-pass filter 410 during rotation in a plane perpendicular to the optical axis, the allowable buckling stress of the piezoelectric element 430 can be accommodated. You can expect. Accordingly, it is possible to prevent buckling destruction of the piezoelectric element 430.

More specifically, the stress F generated at the end of the piezoelectric element 430 by the moment M generated by the rotation in the plane perpendicular to the optical axis is defined by the following formula (1).
F = M / (L / 2) (1)
As is clear from Equation (1), the stress F generated at the end of the piezoelectric element 430 varies depending on the moment M generated and the length L of the piezoelectric element 430 in the direction perpendicular to the optical axis. According to the equation (1), when L is made as long as possible, the stress generated at the end of the piezoelectric element 430 can be reduced, and as a result, it can be within the allowable buckling stress range. Become.

  The allowable buckling stress indicates a limit range of stress applied to the piezoelectric element 430 so that the piezoelectric element 430 is normally driven.

  Next, vibration of the optical low-pass filter 410 will be described.

  When the MPU 100, which is a control means, controls the piezoelectric element 430 to apply a predetermined periodic voltage, the piezoelectric element 430 is in a direction substantially perpendicular to the optical axis and expands and contracts in 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 always kept in contact with each other, the vibration of the piezoelectric element 430 is transmitted to the optical low-pass filter 410.

  As described above, the low-pass filter holding member 420 and the image sensor 33 are sealed by the rubber sheet 520, and the optical low-pass filter 410 and the low-pass filter holding member 420 are sealed by the piezoelectric element 430 and the elastic member 450. Has been. Therefore, the space between the optical low-pass filter 410 and the image sensor 33 is formed as a sealed space from which dust or the like does not enter. At the same time, the low-pass filter unit 470 including the optical low-pass filter 410 and the like is configured to sandwich the rubber sheet 520 with respect to the imaging element unit 500, so that vibration of the low-pass filter unit 470 is absorbed by the rubber sheet 520. Is done. Therefore, the vibration of the low-pass filter unit 470 is hardly transmitted to the image sensor 33.

  With such a configuration, even if the piezoelectric element 430 vibrates, the imaging element 33 is hardly affected. As a result, it is possible to limit the structures that receive vibrations, and it is possible to vibrate the optical low-pass filter 410 that particularly wants to cause vibrations. As a result, the total mass of the structure that receives vibration can be suppressed, and the energy for driving the piezoelectric element 430 can be smaller.

  Furthermore, since 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 applied to the camera.

  Further, as described above, since the optical low-pass filter 410 and the piezoelectric element 430 are not bonded, that is, not coupled, the piezoelectric element 430 can be expanded or contracted by applying a periodic voltage to the piezoelectric element 430. A force is generated only in the direction of pushing out 410, and no force is generated in the direction in which the optical low-pass filter 410 pulls the piezoelectric element 430. Therefore, even if a high frequency voltage in the ultrasonic range is applied to the piezoelectric element 430, an excessive tensile force is not applied to the piezoelectric element 430, and it is possible to prevent damage such as peeling at the laminated portion.

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

  When the cleaning instruction operation member 44 is operated by the photographer, the camera body 1 is shifted to the cleaning mode state in response to an instruction to start the cleaning mode. In this embodiment, the cleaning instruction operation member 44 is provided. However, the present invention is not limited to this, and the operation member for instructing the transition to the cleaning mode is limited to a mechanical button. Instead, an instruction may be given from a menu displayed on the color liquid crystal monitor 19 using a cursor key, an instruction button, or the like.

  The transition to the cleaning mode may be performed automatically during a normal camera sequence such as when the power is turned on, or may be performed on the basis of the number of times of shooting, the date, and the like.

  The power supply circuit 110 supplies power necessary for the cleaning mode to each part of the camera body 1 as necessary. In parallel with this, the remaining battery level of the power source 42 is detected, and the result is transmitted to the MPU 100.

  Upon receiving the cleaning mode start signal, the MPU 100 sends a drive signal to the piezoelectric element drive circuit 111. When the piezoelectric element drive circuit 111 receives a drive signal from the MPU 100, it generates a periodic voltage for driving the piezoelectric element 430 and applies it to the piezoelectric element 430. The piezoelectric element 430 expands and contracts according to the applied voltage. When the piezoelectric element extends, the optical low-pass filter is pushed by the piezoelectric element 430 and moves in a direction orthogonal to the optical axis (plane direction), and the biasing member 440 is contracted 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 contracting 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 a plane horizontal direction perpendicular to the optical axis.

  As described above, the present embodiment has described the case where the low-pass filter unit 470 and the image sensor unit 500 are screwed to the mirror box 5 independently. However, the present invention is not limited to this. For example, the main body chassis 300 may be configured to be screwed independently. Further, for example, the low-pass filter unit 470 may be screwed to the main body chassis 300 and the image sensor unit 500 that needs to be adjusted with the mount surface may be screwed to the mirror box 5. That is, if the low-pass filter unit 470 and the image sensor unit 500 are not rigidly fastened and are fixed to relatively large members, vibration of the low-pass filter unit 470 is difficult to be transmitted to the image sensor unit 500. Can be expected. Therefore, as long as this is the case, it is only necessary to fix each unit to one of the base members.

It is a front perspective view of the digital single-lens reflex camera which is an embodiment of the present invention. It is a back perspective view of the digital single-lens reflex camera which is an embodiment of the present 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. 7 is a front view showing components of a low-pass filter unit 470. FIG. 5 is a detailed view of an elastic member 450. FIG. FIG. 5 is an exploded perspective view for explaining components constituting a unit of a low-pass filter unit 470 and an image sensor unit 500. It is a conceptual diagram for demonstrating the force which generate | occur | produces.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera main body 2 Mount 19 Color liquid crystal monitor 32 Shutter unit 33 Image pick-up element 300 Main body chassis 410 Low pass filter 420 Low pass filter holding member 430 Piezoelectric element 440 Energizing member 450 Elastic member 500 Image pick-up element unit 510 Image pick-up element holding member 520 Rubber sheet 530 Stage Screw

Claims (4)

An image sensor unit including an image sensor that converts an optical image of a subject into an electrical signal;
An optical member disposed on the imaging optical axis in front of the imaging element;
Excitation means for applying vibration to the optical member;
An optical member holding member for holding the optical member;
A base member;
Control means for controlling the vibration of the vibration means,
The image pickup apparatus, wherein the optical image pickup element unit and the optical member holding member are independently fixed to the base member which is a relatively larger member.   The image pickup apparatus according to claim 1, wherein the base member is a mirror box for supporting a mirror for reflecting a photographing light beam to a finder optical system.   The image pickup apparatus according to claim 1, wherein the base member is a main body chassis serving as a skeleton of the image pickup apparatus. The imaging apparatus according to claim 1, wherein a space between the imaging element unit and the optical member holding member is sealed through an elastic member.

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