JP2016149620A - Optical device and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device for stably vibrating an optical member, and a control method thereof.SOLUTION: An optical device includes: an optical member arranged on an imaging optical axis at the front side of an imaging element; a piezoelectric element for vibrating the optical member; and a vibration detection circuit for detecting vibration of the optical member due to driving the piezoelectric element. A control section compares a detected vibration value detected by the vibration detection circuit with a threshold (S704). When the detected vibration value is equal to or larger than the threshold, the control section performs first control of applying a signal of frequency where the detected vibration value of the optical member is equal to the larger than the predetermined threshold, to the piezoelectric element, to execute foreign matter removal processing (S707). When the detected vibration value is less than the threshold, detection information on an environmental temperature of the piezoelectric element is acquired, to set heating drive time, in accordance with the environmental temperature (S705). The control section performs second control of applying a signal of frequency where the detected vibration value of the optical member is equal to or less than the predetermined threshold, to the piezoelectric element (S706), and performs first control (S707).SELECTED DRAWING: Figure 10

Description

  The present invention relates to a technique for removing foreign matters such as dust adhering to the surface of an optical member.

  In an imaging device such as a digital camera that captures an optical image of a subject by converting it into an electrical signal, the imaging element receives the imaging light flux. The photoelectric conversion signal output from the image sensor is converted into image data and recorded on a recording medium such as a memory card. A CCD (Charge Coupled Device) sensor, a CMOS (Complementary Metal Oxide Semiconductor) sensor, or the like is used as the imaging element.

  An optical low-pass filter and an infrared cut filter are disposed on the subject side with respect to the image sensor. In this case, foreign matter such as dust may adhere to the cover glass of the image sensor or the surface of the filter, and if the attached part of the foreign matter appears as a black dot in the captured image, the image looks worse. End up. In particular, in a digital single-lens reflex camera with interchangeable lenses, a mechanical operation unit such as a shutter and a quick return mirror is disposed in the vicinity of the image sensor. When foreign matters such as dust are generated from these operating parts, there is a possibility of adhering to the surfaces of the image sensor and the filter. Further, when the lens is exchanged, if dust or the like enters the camera body from the opening of the lens mount, there is a concern about the adhesion thereof. Patent Document 1 discloses a technique for removing foreign matters such as dust by vibrating an optical member with a piezoelectric element.

JP 2012-49704 A

In the technique disclosed in Patent Document 1, a voltage is applied to a piezoelectric element to drive it, and an optical filter provided on the front side of the imaging element is vibrated by displacing it in the optical axis direction. The vibration force at this time varies depending on the environmental temperature. Therefore, by changing the applied voltage of the piezoelectric element according to the detected environmental temperature, the necessary dustproof performance is exhibited regardless of the environmental temperature. In general, the vibration force is greatly affected by the distortion capability of the piezoelectric element used, but some piezoelectric elements have temperature hysteresis. The temperature hysteresis property is a characteristic in which the strain capability varies depending on the past temperature history even under the same environmental temperature. In the case of a mechanism using a piezoelectric element having temperature hysteresis, it is necessary to take measures against variations in vibration performance exhibited by past temperature history even under the same environmental temperature.
An object of the present invention is to provide an optical apparatus capable of stably vibrating an optical member and a control method thereof.

  An apparatus according to the present invention includes an optical member, vibration means for vibrating the optical member, vibration detection means for detecting the magnitude of vibration of the optical member when the optical member is vibrated by the vibration means, Control means for controlling the drive of the vibration means based on the magnitude of vibration of the optical member detected by the vibration detection means, wherein the control means has a magnitude of vibration of the optical member equal to or greater than a threshold value. A first control for driving the vibration means at a first frequency, and when the magnitude of vibration of the optical member is smaller than a threshold, the vibration means is driven more than when the vibration means is driven at the first frequency. The second control for driving the vibrating means is performed at a second frequency at which the magnitude of the vibration of the optical member is reduced, and the first control is further performed.

  According to the present invention, the optical member can be vibrated stably.

It is a perspective view at the time of seeing the imaging device concerning the embodiment of the present invention from the front side. It is a perspective view at the time of seeing the imaging device concerning the embodiment of the present invention from the back side. It is a block diagram which shows the electric constitution in this embodiment. 1 is an exploded perspective view illustrating a schematic configuration inside an imaging apparatus according to an embodiment. FIG. 5 is an exploded perspective view illustrating a configuration of the imaging unit 400 in FIG. 4. FIG. 6 is a perspective view illustrating a configuration of a vibration unit 470 in FIG. 5. It is sectional drawing which follows the XX line of FIG. It is a figure which illustrates the relationship between temperature and a vibration detection value about temperature history. It is a flowchart explaining the example of a process in this embodiment. 10 is a flowchart illustrating a foreign matter removing operation S605 in FIG. 9. It is a figure which illustrates the relationship between a frequency and a vibration detection value.

  Hereinafter, optical devices according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, an imaging apparatus is illustrated and a configuration example using a piezoelectric element as a vibration element that vibrates an optical member will be described. However, the present invention includes a mechanism that vibrates an optical member using various vibration elements. It is applicable to optical equipment.

  1 and 2 are views showing the appearance of a digital single-lens reflex camera as an example of an imaging apparatus according to the present embodiment. FIG. 1 is a perspective view when the camera is viewed from the front side, and shows a state in which the taking lens unit is removed. FIG. 2 is a perspective view when the camera is viewed from the back side. Below, the subject side is defined as the front side, and the positional relationship of each part will be described.

  The camera body 1 in FIG. 1 includes a grip 1a that protrudes forward so that the user can easily hold the camera stably during shooting. The mount part 2 is a part for fixing a detachable taking lens unit (not shown) to the camera body part 1. Control signals, status signals, data signals, and the like are transmitted and received between the camera body 1 and the photographic lens unit via the mount contact 21, and power is supplied from the camera body 1 to the photographic lens unit. In addition, about the mount contact part 21, it is good also as a structure which can perform optical communication, audio | voice communication, etc. not only in electrical communication.

  The lens lock release button 4 is an operation member that the user pushes in when removing the photographing lens unit. The mirror box 5 is arranged in the camera casing, and guides the photographic light flux that has passed through the photographic lens. A quick return mirror 6 is disposed inside the mirror box 5. The quick return mirror 6 can take a first state and a second state. The first state is a state in which the quick return mirror 6 is held at an angle of 45 ° with respect to the photographing optical axis in order to guide the photographing light flux toward the pentaprism 22 (see FIG. 3). The second state is a state in which the quick return mirror 6 is held at a position retracted from the optical axis in order to guide the photographing light flux in the direction of the image sensor 33 (see FIG. 3).

  In the camera main body 1, a shutter release button 7 for starting operation for starting photographing is arranged on the upper part of the grip portion 1a. In the shutter release button 7, the first switch SW1 (FIG. 3: 7a) is turned ON in the first stroke (half-pressing operation), and the second switch SW2 (FIG. 3: 7b) in the second stroke (full-pressing operation). Is configured to turn ON. A main operation dial 8 is disposed near the shutter release button 7. The main operation dial 8 is an operation member for setting the shutter speed and the lens aperture value according to the operation mode at the time of shooting. The plurality of operation buttons 10 are photographing system upper surface operation mode setting buttons. Some of the operation results of these operation members are displayed on the LCD display panel 9. The top surface operation mode setting button 10 is used when the user performs setting such as continuous shooting or single frame shooting by pressing the shutter release button 7 once, or setting of a self-shooting mode. Then, the setting status is displayed on the LCD display panel 9.

  A flash unit 11 that performs a pop-up operation with respect to the camera body 1, a flash mounting shoe groove 12, and a flash contact 13 are disposed in the upper center of the camera body 1. When viewed from the front, a shooting mode setting dial 14 is arranged on the right side of the upper part of the camera.

  An external terminal lid 15 that can be opened and closed is provided on the side of the camera body 1 opposite to the grip 1a. When the user opens the external terminal lid 15, a video signal output jack 16 and a USB output connector 17 are housed inside as an external interface (in FIG. 1, the connecting portion is partially shown in a transparent state).

  The viewfinder eyepiece window 18 shown in FIG. 2 is provided above the back side of the camera body 1. A color liquid crystal monitor 19 arranged in the vicinity of the center of the back constitutes an image display unit for displaying captured images and the like. A sub operation dial 20 is disposed on the right side of the color liquid crystal monitor 19, and plays a supplementary role for the function of the main operation dial 8. For example, in the AE (automatic exposure) mode of the camera, the sub operation dial 20 is used to set an exposure correction amount with respect to an appropriate exposure value calculated by the automatic exposure device. Alternatively, in the manual mode in which the user sets each of the shutter speed and the lens aperture value, the user sets the shutter speed using the main operation dial 8 and sets the lens aperture value using the sub operation dial 20. The sub operation dial 20 is also used for selecting display of a captured image displayed on the color liquid crystal monitor 19. Furthermore, when the sub operation dial 20 is operated in the shooting standby state of the camera body 1, a foreign matter removal function execution menu is displayed on the screen of the color liquid crystal monitor 19.

  A plurality of operation members (see 43 to 45) are arranged on the left side of the color liquid crystal monitor 19 on the rear surface of the camera body 1. The main switch 43 is an operation member used by the user to start or stop the operation of the camera. The live view (hereinafter also referred to as LV) display instruction member 44 is an operation member used to activate and stop the LV display mode. Depending on the operation of the LV display instruction member 44, the LV image is displayed on the screen of the color liquid crystal monitor 19 or not displayed. The moving image recording instructing member 45 is an operation member used for operating and stopping the moving image recording mode. When the user operates the moving image recording instruction member 45, the imaging apparatus starts recording a moving image.

  FIG. 3 is a block diagram illustrating the main electrical configuration of the imaging apparatus according to this embodiment. The photographic lens unit is used in a state of being mounted on the camera body 1, and optical members such as the photographic lens 200 and the diaphragm 204 constituting the photographic optical system are arranged on the photographic optical axis 50. In FIG. 3, for convenience, the photographing lens 200 including a lens group is simplified and shown as one lens.

  The camera body 1 includes a central processing unit (hereinafter referred to as MPU) of a microcomputer as a control center. The MPU 100 that controls the entire camera performs various processes and instructions to each unit. The MPU 100 includes an EEPROM (Electrically Erasable Programmable Read-Only Memory) 100a. The EEPROM 100a can store time information of the time measuring circuit 109 and other information at any time, and stores data of reference tables (temperature-vibration detection value conversion table h and temperature-heat generation drive time table w) described later. Yes.

  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, a photometry circuit 106, and a temperature sensor 112. In addition, a liquid crystal display driving circuit 107, a battery check circuit 108, a time measuring circuit 109, a power supply circuit 110, a piezoelectric element driving circuit 111, and a vibration detection circuit 113 are connected to the MPU 100. These circuits operate under the control of the MPU 100.

  The MPU 100 communicates with the lens control circuit 201 disposed in the photographing lens unit via the mount contact portion 21. When the photographic lens unit is connected to the mount unit 2, transmission from the lens control circuit 201 to the MPU 100 is possible via the mount contact unit 21. The lens control circuit 201 communicates with the MPU 100 to control driving of the photographing lens 200 and the diaphragm 204 in the photographing lens unit. An AF (autofocus) drive circuit 202 drives a stepping motor, for example, according to a control signal from the lens control circuit 201 to move a focus lens in the photographing lens 200. Focus adjustment is performed by changing the position of the focus lens. A diaphragm driving circuit 203 drives the diaphragm 204 in accordance with a control signal from the lens control circuit 201. For example, in the case of a configuration such as an auto iris, control is performed so as to obtain an optical aperture value by changing the aperture diameter of the aperture 204.

  The main mirror 6 in the camera body 1 guides the photographic light beam passing through the photographic lens 200 to the pentaprism 22 and transmits a part of the light to the sub mirror 30. The sub mirror 30 guides a part of the photographing light flux to the focus detection sensor unit 31. The mirror driving circuit 101 drives the main mirror 6 and moves it to a position where the subject image can be observed by the viewfinder or a retracted position retracted from the photographing optical axis 50. In conjunction with the main mirror 6, the sub mirror 30 moves to a position for guiding a part of the photographic light flux to the focus detection sensor unit 31, or to a retreat position retracted from the photographic optical axis 50. Specifically, the mirror drive circuit 101 is composed of a DC motor and a gear train.

  The focus detection sensor unit 31 is a phase difference type focus detection unit, and includes a field lens, a reflection mirror, a secondary imaging lens, a diaphragm, a line sensor including a plurality of CCDs, and the like disposed in the vicinity of an imaging surface (not shown). Consists of The output signal of 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. Thereby, the defocus amount and the defocus direction are determined. The lens control circuit 201 moves the focus lens in the photographic lens 200 to the in-focus position via the AF drive circuit 202 in accordance with the control command of the MPU 100.

  The pentaprism 22 is an optical member that converts and reflects an imaging light beam reflected by the main mirror 6 into an erect image. The user can observe the subject image through the finder eyepiece window 18 via the finder optical system. The pentaprism 22 guides a part of the photographic light flux to the photometric sensor 46, and the photometric circuit 106 acquires the output signal of the photometric sensor 46, 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 luminance signal.

  The focal plane shutter 32 blocks the photographing light beam when the user observes the subject image with the finder optical system. Further, during imaging, the focal plane shutter 32 is configured to obtain a desired exposure time based on a time difference during which a front blade group and a rear blade group (not shown) travel in accordance with a shutter release signal. The shutter drive circuit 103 drives the focal plane shutter 32 according to the control signal of the MPU 100.

  The image sensor 33 is an image sensor of various forms such as a CMOS type, a CCD type, and a CID (Charge Injection Device) type. The clamp / CDS (correlated double sampling) circuit 34 can perform analog processing before A (Analog) / D (Digital) conversion and change the clamp level. An AGC (automatic gain control) unit 35 performs analog processing before A / D conversion and can change the AGC basic level. The A / D converter 36 converts the analog output signal of the image sensor 33 into a digital signal.

  The infrared cut filter 410 is a rectangular optical member that removes high spatial frequency components. As will be described later, the surface of the infrared cut filter 410 is coated so as to have conductivity in order to prevent adhesion of foreign matters. The optical low-pass filter 420 has a structure in which a plurality of birefringent plates and phase plates made of quartz are laminated and laminated. The optical low-pass filter 420 separates the light beam incident on the image sensor 33 into a plurality of light beams, and effectively reduces the generation of false resolution signals and false color signals.

  The piezoelectric element drive circuit 111 is a circuit that vibrates the piezoelectric element 430 fixed to the infrared cut filter 410. The piezoelectric element driving circuit 111 vibrates the piezoelectric element 430 in accordance with an instruction from the MPU 100 and causes the infrared cut filter 410 to vibrate. A method for driving the piezoelectric element 430 will be described later. The temperature sensor 112 is disposed in the vicinity of the infrared cut filter 410. The temperature sensor 112 functions as temperature detection means for detecting the environmental temperature. The temperature sensor 112 detects the temperature in the camera body 1 and outputs a temperature detection signal to the MPU 100. The vibration detection circuit 113 detects the amplitude of vibration generated in the infrared cut filter 410 and outputs a vibration detection value (amplitude) signal to the MPU 100. The vibration detection circuit 113 functions as a vibration detection unit that detects the magnitude of vibration of the infrared cut filter 410 when the infrared cut filter 410 is vibrated by the piezoelectric element drive circuit 111. The imaging unit 400 is a component unit in which the infrared cut filter 410, the piezoelectric element 430, the imaging element 33, and the like are unitized together with other components to be described later. Details of a specific configuration will be described later.

  The video signal processing circuit 104 performs overall image processing by hardware, such as gamma / knee processing, filter processing, and information composition processing for monitor display, on the image data digitized by the A / D converter 36. The moving image data and still image data for monitor display output from the video signal processing circuit 104 are output to the color liquid crystal monitor 19 via the color liquid crystal drive circuit 114 and image display is performed. Further, the video signal processing circuit 104 can store image data in the buffer memory 37 through the memory controller 38 in accordance with an instruction from the MPU 100. Furthermore, the video signal processing circuit 104 has a JPEG (Joint Photographic Experts Group) compression function for image data. In the case of continuous shooting such as continuous shooting, image data is temporarily stored in the buffer memory 37, and unprocessed image data is sequentially read out through the memory controller 38. As a result, the video signal processing circuit 104 can sequentially execute image processing and compression processing regardless of the transfer speed of the input image data from the A / D converter 36.

  The memory controller 38 stores image data input from the external interface unit 40 (including the video signal output jack 16 and the USB output connector 17 of FIG. 1) in the memory 39. Further, the memory controller 38 causes the image data stored in the memory 39 to be output from the external interface unit 40. The memory 39 is, for example, a flash memory that can be attached to and detached from the camera body 1.

  The power supply unit 42 supplies necessary power to each unit of the imaging apparatus. The power supply circuit 110 supplies, for example, necessary power in a predetermined mode (hereinafter referred to as a cleaning mode) from the power supply unit 42 to each unit of the camera body unit 1 as necessary. The cleaning mode is a mode in which the user can directly clean the foreign matter on the infrared cut filter 410 using a cotton swab, sylbon paper, rubber or the like. In parallel with this, the power supply circuit 110 detects the remaining battery level of the power supply unit 42 and transmits a detection signal to the MPU 100. When the MPU 100 receives the instruction signal for starting the cleaning mode, the MPU 100 moves the main mirror 6 and the sub mirror 30 to the retracted position via the mirror driving circuit 101, respectively. Further, the MPU 100 drives the focal plane shutter 32 to the retracted position via the shutter drive circuit 103.

  The switch sense circuit 105 transmits an input signal corresponding to the operation state of various switches to the MPU 100. The first switch (SW1) 7a is turned on by operating the first stroke of the shutter release button 7, and the second switch (SW2) 7b is turned on by operating the second stroke of the shutter release button 7. When the second switch SW2 is turned on, a shooting start instruction signal is transmitted to the MPU 100. The switch sense circuit 105 detects the operation states of the main operation dial 8, the sub operation dial 20, the shooting mode setting dial 14, the main switch 43, the LV display instruction member 44, and the moving image recording instruction member 45. For example, when the user operates the LV display instruction member 44, the switch sense circuit 105 transmits an instruction signal for displaying or not displaying a moving image on the color liquid crystal monitor 19 to the MPU 100. When the moving image recording instruction member 45 is operated, the switch sense circuit 105 transmits to the MPU 100 a start or stop instruction signal for recording the moving image data generated by the video signal processing circuit 104 in the memory 39.

  The liquid crystal display driving circuit 107 drives the LCD display panel 9 and the in-finder liquid crystal display device 41 according to the control signal of the MPU 100. The battery check circuit 108 performs a battery check for a predetermined time according to the control signal of the MPU 100 and transmits a detection signal to the MPU 100. The time measurement circuit 109 measures the elapsed time from the time when the main switch 43 is turned off to the next time when the main switch 43 is turned on, and performs time measurement processing (acquisition of time and date, etc.). Is transmitted to the MPU 100.

  Next, the configuration of the imaging unit 400 will be described in detail with reference to FIGS. FIG. 4 is an exploded perspective view showing a schematic configuration inside the camera in order to explain the holding structure of the peripheral portion of the infrared cut filter 410 and the image sensor 33.

  The main body chassis 300 is a skeleton member of the camera main body 1. The mirror box 5, the focal plane shutter 32, the main body chassis 300, and the imaging unit 400 are arranged in this order from the front side (subject side). In particular, the image pickup unit 400 is fixed to the main body chassis 300 by adjusting the image pickup surface of the image pickup element 33 at a predetermined distance and parallel to the mounting surface of the mount unit 2 as a reference for attaching the photographing lens unit. Is done.

  FIG. 5 is a perspective view illustrating a configuration example of the imaging unit 400. The imaging unit 400 includes a vibration unit 470 and an imaging element unit 500. The image sensor unit 500 includes at least the image sensor 33, an image sensor holding member 510, a circuit board 520, a shield case 530, an optical low-pass filter 420, a light shielding member 540, and an optical low-pass filter holding member 550. The image sensor holding member 510 is made of metal or the like, and is provided with a plurality of positioning pins 510a, screw holes 510b, and screw holes 510c. An electric circuit of an imaging system is mounted on the circuit board 520, and a screw escape hole 520a is formed. The shield case 530 is made of metal or the like, and has a screw escape hole 530a. The circuit board 520 and the shield case 530 are fastened and fixed to the image sensor holding member 510 with screws using screw escape holes 520a, escape holes 530a, and screw holes 510b. The shield case 530 is connected to a ground potential on the circuit in order to protect the electric circuit from static electricity or the like.

  An opening corresponding to the effective area of the photoelectric conversion surface of the image sensor 33 is formed in the light shielding member 540, and double-sided tapes are respectively fixed to the front side and the back side. The optical low-pass filter holding member 550 is fixed to the cover glass 33a (see FIG. 7) of the image sensor 33 using the double-sided tape of the light shielding member 540. The optical low-pass filter 420 is positioned at a predetermined location on the opening edge of the optical low-pass filter holding member 550 and is fixedly held on the light shielding member 540 with double-sided tape.

  The vibration unit 470 includes an infrared cut filter 410 and a holding member 460 thereof, and a piezoelectric element described later. The holding member 460 has a plurality of positioning holes 460a and screw escape holes 460b. The surface of the infrared cut filter 410 is coated so as to have conductivity. The vibration unit 470 is positioned with respect to the image sensor unit 500 using the positioning hole 460a and the positioning pin 510a of the image sensor holding member 510. The vibration unit 470 is fastened and fixed to the image sensor unit 500 with screws using the screw escape holes 460b and the screw holes 510c of the image sensor holding member 510 with the elastic member 450 interposed therebetween. As a result, the electricity charged on the surface of the infrared cut filter 410 can be released to the circuit board 520 through the holding member 460, the image sensor holding member 510, and the shield case 530, thereby preventing foreign matter from adhering.

  The elastic member 450 is formed of a soft material such as rubber and has a role as a vibration absorbing member of the infrared cut filter 410 and forms a sealed space between the infrared cut filter 410 and the optical low-pass filter 420 as described later. The elastic member 450 is formed of a thick member or a member having low hardness in order to increase the vibration absorption of the infrared cut filter 410 and abuts on a vibration node of the infrared cut filter 410.

  The configuration of the vibration unit 470 will be described in detail with reference to FIG. FIG. 6 is a perspective view showing the vibration unit 470. The vibration unit 470 includes at least an infrared cut filter 410, a piezoelectric element 430, and a holding member 460.

  The holding member 460 is formed as a single part from an elastic material (metal or the like), and has a plurality of positioning holes 460a and screw escape holes 460b. The holding surface 460c (see FIG. 5) of the holding member 460 is fixed to the infrared cut filter 410 with a conductive adhesive or the like in the vicinity of the four corners including the vibration node. The connecting portions of the flat portions 460 d provided on the sides of the holding member 460 are bent in the optical axis direction parallel to the vibration direction of the infrared cut filter 410. The piezoelectric element 430 is fixed to the end of the rectangular infrared cut filter 410 by bonding or the like. In the infrared cut filter 410 of the present embodiment, two piezoelectric elements 430a and 430b having the same shape are fixed to both ends in the long side direction.

  7 is a cross-sectional view taken along line XX in FIG. The light shielding member 540 has a front surface portion in contact with the optical low-pass filter 420, and a rear surface portion in contact with the cover glass 33 a of the image sensor 33. Double-sided tape is affixed to the front side and the back side of the light shielding member 540, and the optical low-pass filter 420 is fixedly held on the cover glass 33c of the image sensor 33 by the double-sided tape of the light shielding member 540. Thereby, the gap between the optical low-pass filter 420 and the cover glass 33a of the image sensor 33 is sealed by the light shielding member 540, and a sealed space is formed to prevent entry of foreign matters such as dust.

  A part on the front side of the elastic member 450 is in contact with the infrared cut filter 410, and a part on the back side is in contact with the optical low-pass filter 420. Since the vibration unit 470 is biased toward the image sensor unit 500 by the spring elasticity of the holding member 460, the elastic member 450 and the infrared cut filter 410 are in close contact with each other without a gap. The elastic member 450 and the optical low-pass filter 420 are in close contact with each other without a gap. As a result, the gap between the infrared cut filter 410 and the optical low-pass filter 420 is sealed by the elastic member 450 to form a sealed space that prevents entry of foreign matters such as dust.

Next, the foreign substance removal operation of the vibration unit 470 will be described.
The piezoelectric element driving circuit 111 applies a voltage having a predetermined frequency to the piezoelectric element 430 fixed to the infrared cut filter 410 according to the control signal of the MPU 100. The piezoelectric element 430 expands and contracts in a direction perpendicular to the optical axis, and causes the infrared cut filter 410 to bend and vibrate. Since the frequency of the voltage applied to the piezoelectric element 430 is set in the vicinity of the resonance frequency of the natural mode of the infrared cut filter 410, large vibrations can be generated with a smaller voltage. In the vicinity of the non-resonant frequency, the vibration is reduced, but the heat generation of the piezoelectric element 430 due to energy loss can be further promoted.

  Next, the vibration detection operation of the vibration unit 470 will be described. The MPU 100 acquires the vibration force detection signal of the infrared cut filter 410. Specifically, a voltage having a predetermined frequency is applied to one of the plurality of piezoelectric elements 430, for example, the piezoelectric element 430a to generate bending vibration, and the vibration propagates to the other piezoelectric element 430b. The piezoelectric element 430b outputs a voltage accompanying vibration. The vibration detection circuit 113 detects and digitizes the voltage output from the piezoelectric element 430b, and outputs a detection signal to the MPU 100. Thereby, the MPU 100 can detect the magnitude (amplitude) of the vibration of the infrared cut filter 410 according to the voltage and frequency applied to the piezoelectric element 430. Hereinafter, the magnitude of vibration acquired by the MPU 100 is referred to as “vibration detection value”. As the vibration detection value is higher, the vibration generated in the infrared cut filter 410 is larger, and thus it can be said that the foreign matter removing ability is higher. With reference to the graph shown in FIG. 8, the fluctuation | variation of the foreign material removal capability according to the temperature history and environmental temperature of the vibration unit 470 in this embodiment is demonstrated.

  FIG. 8 illustrates a graph in which the maximum vibration detection value obtained by the vibration detection operation for each environmental temperature is plotted. The horizontal axis represents the environmental temperature, and the vertical axis represents the vibration detection value in arbitrary units. The vibration detection value at each temperature is acquired twice, and the first vibration detection value is obtained by gradually decreasing the environmental temperature in a predetermined temperature increment from the environment of the temperature T4 (hereinafter referred to as a temperature decrease history result). ). The vibration detection value at the second time indicates a result (hereinafter referred to as a temperature rise history result) acquired while gradually increasing the environmental temperature in a predetermined temperature increment from the environment of the temperature T1. A solid line 801 is a graph line illustrating the temperature decrease history result, and a broken line 802 is a graph line illustrating the temperature increase history result. As can be seen from the comparison between the line 801 and the line 802, the two lines 801 and 802 overlap in the range where the environmental temperature is from T1 to T2 and the range from T3 to T4. Are the same. That is, in this environmental temperature range, the vibration unit 470 exhibits a stable foreign matter removal capability regardless of the temperature history. On the other hand, in the range from T2 to T3, the temperature decrease history result and the temperature increase history result are different even under the same environmental temperature. That is, in this environmental temperature range, the vibration unit 470 is affected by the temperature hysteresis property of the piezoelectric element, so that it is difficult to stably exhibit the foreign substance removal capability. This result shows that, even if the foreign matter removal operation is executed in a situation where the environmental temperature does not reach T3, for example, the foreign matter removal capability may be high or low depending on the temperature history. From the purpose of the foreign matter removing function, it is clear that it is desirable to avoid the destabilization of the foreign matter removing operation and to always exhibit high ability.

  In the example shown in FIG. 8, the vibration unit 470 can exhibit the maximum capability in the unstable temperature range of the foreign matter removal capability when the temperature is T3 or higher in the past temperature history. This can be seen from the fact that the lines 801 and 802 overlap in the temperature range of T3 or higher. Hereinafter, a state where the vibration detection value indicated by the line 801 is generated in the vibration unit 470 in a predetermined temperature range (a range from T2 to T3) is referred to as a “temperature decrease history state”.

  With reference to FIG. 9, the foreign substance removal operation in the present embodiment will be described. The process shown in the flowchart of FIG. 9 is realized by the MPU 100 of FIG. 3 reading and executing a program. In FIG. 9, when the user depresses the main switch 43 of the camera body 1, the power of the camera body 1 is turned on and the camera is activated (S601). The MPU 100 executes an initial procedure when starting up the camera body 1 (S602). The initial procedure is to check whether the power supply voltage level and the switch system provided in the camera body 1 are normal, whether or not a recording medium is mounted, whether or not a photographic lens is mounted, and for shooting. For example, initial settings. After execution of the initial procedure, the imaging apparatus enters a shooting standby state (S603).

  Next, the MPU 100 determines whether or not a foreign matter removal operation is instructed from the foreign matter removal function menu by the user operating the sub operation dial 20 (S604). As a result of the determination, if a foreign matter removing operation is instructed, the process proceeds to S605. If a foreign matter removing operation is not instructed, the process proceeds to S606. The instruction of the foreign substance removal operation by the user is not limited to an instruction from the menu, and may be performed using a mechanical switch by operating a foreign matter removal operation instruction button, for example. In S605, a foreign matter removing operation is performed. Details of the foreign matter removing operation will be described later with reference to FIG. It progresses to S606 after S605.

  In S606, the MPU 100 determines whether or not the shutter release button 7 of the camera body 1 is pressed by the user and the release switches (SW1, SW2) are turned on. If the result of determination is that the shutter release button 7 has not been pressed, processing returns to S603, and the imaging apparatus maintains the shooting standby state. On the other hand, if the shutter release button 7 has been pressed, the process proceeds to S607. In step S <b> 607, the camera body 1 performs a shooting operation. Since the shooting operation is a well-known operation in a mode in which shooting and setting are performed in a generally known camera, detailed description thereof is omitted. After the photographing operation is finished, a series of processing is finished (S608).

  FIG. 10 is a flowchart illustrating the flow of the foreign substance removal operation performed in S605 of FIG. The MPU 100 immediately executes the foreign substance removal operation by the first control using the resonance frequency related to the vibration unit 470, or executes the heat generation process by the second control using the non-resonance frequency, and once the temperature of the piezoelectric element 430 is reached. The foreign matter removing operation is performed after raising. As described above, since the strain performance of the piezoelectric element 430 changes depending on the temperature history, highly stable foreign substance removal performance can be obtained by the following series of operations.

  In S701 of FIG. 10, the MPU 100 stores the detected temperature data acquired from the temperature sensor 112 in the EEPROM 100a as the temperature p, and then proceeds to S702. In step S702, the MPU 100 refers to the temperature-vibration detection value conversion table h recorded in advance in the EEPROM 100a, and acquires the maximum vibration detection value corresponding to the temperature p. The temperature-vibration detection value conversion table h is a table showing the maximum vibration detection value for each temperature created based on the result indicated by the line 801 in FIG. The maximum vibration detection value corresponding to the temperature p is stored as a vibration threshold value n in the EEPROM 100a. That is, the vibration threshold value n represents a vibration detection value when the foreign substance removal capability that can be exhibited by the vibration unit 470 is the highest under the current environmental temperature.

  In next step S703, the MPU 100 controls the piezoelectric element driving circuit 111 to apply a predetermined voltage to the piezoelectric element 430a while sweeping the frequency in a predetermined frequency band. At the same time, the MPU 100 acquires the vibration detection value output from the vibration detection circuit 113, and temporarily stores it in the EEPROM 100a as a vibration detection value distribution table in association with the frequency of the voltage signal to be applied. After completing the frequency sweep drive for the piezoelectric element 430a, the MPU 100 refers to the vibration detection value distribution table and determines the first frequency that is the vibration detection value equal to or higher than the first threshold as the resonance frequency. The first threshold value (hereinafter referred to as α) is a vibration detection value that is a certain level or more that can be determined as the resonance frequency of the infrared cut filter 410. The MPU 100 refers to the vibration detection value distribution table and determines the second frequency that becomes the vibration detection value equal to or lower than the second threshold value as the non-resonant frequency. The second threshold (hereinafter referred to as β) is a value that can be determined as the non-resonant frequency of the vibration unit 470, and is a value smaller than the first threshold α (β <α). Then, the MPU 100 determines the maximum vibration detection value as the maximum vibration detection value m. In the present embodiment, the voltage transmitted from the piezoelectric element 430 in the vibration detection operation is used. However, an electric current applied to the piezoelectric element may be used. Here, the resonance frequency and the non-resonance frequency will be described with reference to FIG.

  FIG. 11 is a graph illustrating the vibration detection value distribution table stored in the EEPROM 100a by the MPU 100 in S703 of FIG. The horizontal axis represents frequency, and the vertical axis represents vibration detection values in arbitrary units. As can be seen from the distribution of vibration detection values, the vibration detection value is particularly large at the frequency fa. That is, the frequency fa can be determined as the resonance frequency of the vibration unit 470. The frequency fa corresponds to the first frequency, and is a frequency at which the vibration detection value is equal to or higher than the first threshold, and is set in a frequency band including the resonance frequency of the vibration unit 470. Further, the frequency fb (<fa) has the minimum vibration detection value, and can be determined to be a non-resonant frequency of the vibration unit 470. The frequency fb corresponds to the second frequency and is set to a frequency band in which the vibration detection value is equal to or lower than the second threshold and does not include the resonance frequency of the infrared cut filter 410.

  In S704 of FIG. 10, the MPU 100 compares the maximum vibration detection value m stored in the EEPROM 100a with the vibration threshold value n. As a result of the comparison, when the maximum vibration detection value m is smaller than the vibration threshold value n (m <n), the process proceeds to S705, and when the maximum vibration detection value m is greater than or equal to the vibration threshold value n, the process proceeds to S707. The process proceeds from S704 to S705 when the temperature p is in the range from T2 to T3 in FIG. 8 and the vibration unit 470 is not in the temperature decrease history state. On the other hand, the transition from S704 to S707 is a case where the temperature p is outside the range of T2 to T3 in FIG. 8 or the vibration unit 470 is in the temperature drop history state.

  In step S705, the MPU 100 refers to the temperature-heat generation drive time table w stored in the EEPROM 100a in advance, and sets the length of time corresponding to the temperature p as the heat generation drive time t. The heat generation drive time table w is a data table showing the length of time until the temperature of the piezoelectric element 430 rises to T3 when the heat generation processing of the piezoelectric element 430 is performed in S706 described later, for each temperature. The data of the heat generation drive time t is stored in the EEPROM 100a, and the process proceeds to S706. In the present embodiment, a process for determining the heat generation drive time t from the temperature p using the temperature-heat generation drive time table w will be described. In addition, there is a process of setting the length of time calculated from the maximum temperature at which the vibration unit 470 is in the temperature decrease history state, the current temperature, and the temperature increase rate of the piezoelectric element 430 as the heat generation drive time t.

  In step S <b> 706, the MPU 100 controls the piezoelectric element driving circuit 111 and applies a predetermined voltage to the piezoelectric element 430 at the non-resonant frequency fy over the heat generation driving time t. As a result of this process, the temperature of the piezoelectric element 430 rises to T3, so that the vibration unit 470 enters the temperature lowering history state from T3. Therefore, the vibration unit 470 can exhibit the maximum vibration capability (foreign matter removal capability). After S706, the process proceeds to S707. In step S707, foreign matter removal processing is executed. Specifically, the MPU 100 controls the piezoelectric element driving circuit 111 and applies a voltage having a resonance frequency fx to the piezoelectric element 430 with a predetermined parameter. Since the resonance frequency fx is the resonance frequency of the infrared cut filter 410, the foreign matter removal processing can be performed efficiently. After the foreign substance removal process is executed, the process proceeds to S606 in FIG.

  In the present embodiment, the first control to apply a signal having a frequency at which the vibration detection value of the optical member is equal to or higher than the first threshold value to the vibration element, and the frequency at which the vibration detection value of the optical member is equal to or lower than the second threshold value. A second control for applying a signal to the vibration element is executed. When the vibration detection value is less than the vibration threshold value, the foreign matter removal processing is performed by increasing the temperature of the vibration element by the second control and then executing the first control. According to this embodiment, the vibration performance can be exhibited stably and efficiently regardless of the temperature hysteresis property of the vibration element. That is, it is possible to provide an optical apparatus that performs a stable foreign matter removing operation.

  In the present embodiment, the configuration that excites bending vibration in the infrared cut filter 410 has been described. However, the present invention is not limited to this, and an optical low-pass filter configured by bonding a birefringent plate, a phase plate, and an infrared cut filter, a configuration that excites bending vibration in a birefringent plate or a phase plate alone may be used.

33: Image sensor 100: MPU
111: Piezoelectric element drive circuit 112: Temperature sensor 113: Vibration detection circuit 400: Imaging unit 410: Infrared cut filter 430: Piezoelectric element 470: Vibration unit

Claims (11)

An optical member;
Vibration means for vibrating the optical member;
Vibration detecting means for detecting the magnitude of vibration of the optical member when the optical member is vibrated by the vibrating means;
Control means for controlling the drive of the vibration means based on the magnitude of vibration of the optical member detected by the vibration detection means;
The control means includes
When the magnitude of the vibration of the optical member is equal to or greater than a threshold value, a first control for driving the vibrating means at a first frequency is performed,
When the magnitude of vibration of the optical member is smaller than a threshold value, the vibrating means is driven at a second frequency where the magnitude of vibration of the optical member is smaller than when the vibrator is driven at the first frequency. An optical apparatus that performs the second control and further performs the first control.   The vibration detecting unit is configured to vibrate the optical member based on a voltage output from the vibrating unit when the vibrating unit vibrates the optical member or a current flowing when a voltage is applied to the vibrating unit. The optical device according to claim 1, wherein the size of the optical device is detected. Having temperature detecting means for detecting the environmental temperature,
The optical apparatus according to claim 1, wherein the threshold value is changed based on the environmental temperature detected by the temperature detection unit. Having temperature detecting means for detecting the environmental temperature,
4. The method according to claim 1, wherein the control unit changes a length of time for performing the second control based on the environmental temperature detected by the temperature detection unit. 5. The optical instrument described.   The control means stores the magnitude of the vibration of the optical member detected by the vibration detection means and the frequency for driving the vibration means in association with each other in the storage means, and the magnitude of the vibration of the optical member stored. Is determined as the first frequency, and the frequency at which the magnitude of vibration of the optical member is equal to or lower than the second threshold is determined as the second frequency. The optical apparatus of any one of Claim 1 to 4.   The optical apparatus according to claim 5, wherein the second threshold value is smaller than the first threshold value.   The optical apparatus according to claim 1, wherein the first frequency is higher than the second frequency.   The optical apparatus according to claim 1, wherein the vibration unit has a temperature hysteresis property. An image sensor for imaging a subject is provided,
9. The optical apparatus according to claim 1, wherein the optical member is disposed closer to a subject side than the imaging element. The first frequency is a frequency at which the magnitude of vibration of the optical member is equal to or greater than a first threshold, and is set within a frequency band including a resonance frequency of the optical member,
The second frequency is set in a frequency band in which the magnitude of vibration of the optical member is equal to or less than a second threshold and does not include a resonance frequency of the optical member. The optical apparatus according to any one of 1 to 9. A control method for an optical device comprising an optical member and a vibration means for vibrating the optical member,
A detection step of detecting the magnitude of vibration of the optical member when the optical member is vibrated by the vibration means;
A control step for controlling the driving of the vibration means based on the magnitude of vibration of the optical member,
In the control step,
When the magnitude of the vibration of the optical member is equal to or greater than a threshold value, a first control for driving the vibrating means at a first frequency is performed,
When the magnitude of vibration of the optical member is smaller than a threshold value, the vibrating means is driven at a second frequency where the magnitude of vibration of the optical member is smaller than when the vibrator is driven at the first frequency. A control method for an optical apparatus, wherein the first control is performed after performing the second control.