JP2005062686A - Mirror drive system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mirror drive system which can precisely drive the mirror at a high speed, while reducing the mirror drive impacts in a single-lens reflex camera. <P>SOLUTION: The quick-return mirror 15a of a single-lens reflex camera is supported by a mirror drive mechanism 35 and can move to the position to use the view finder or to the retreating position for exposure. The movement of the mirror 15a is stopped by friction of a vibrator brake 40a or 40b, at the view finder position or the exposure retreating position. The friction of the vibrator brake 40a or 40b is removed by the vibrator brake drive circuit 42. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mirror driving system for a single-lens reflex camera.

  As is well known, a mirror of a single-lens reflex camera is generally in a finder observation position before photographing, and a photographer can observe an image from a photographing lens. On the other hand, at the time of photographing, it is retracted from the optical path from the photographing lens to the film surface to become an exposure retreat position and exposed to the image sensor or film. When the exposure is completed, a quick return mirror system is employed in which the finder observation position is restored again.

  However, if the stored spring is driven by the opening force of the stored spring, a shock of collision occurs at the time of contact. This shock causes camera shake during exposure because the entire camera body is shaken during shooting.

  Also, when trying to shorten the release time lag (the time from when the shutter button is pressed until the actual exposure is performed) or when trying to increase the number of frames that can be shot per second by shortening the shooting frame interval for continuous shooting In order to achieve this, the operating time of the mirror must be increased. However, a bounce occurs when the mirror reaches the shooting position and collides with the stopper member of the mirror, and eventually a long time is required until the mirror retracts to a position that does not affect the shooting. Therefore, it has been difficult to shorten the release time lag or increase the number of frames that can be shot per second.

  As a conventional example for solving this difficulty, for example, a mirror jumping means for allowing a mirror that has been urged downward to be flipped up by forward movement and allowed to be lowered by backward movement, and an air damper having a control movable part There is known a technical means for reducing shock by providing and braking the air damper in conjunction with the mirror jumping means (see, for example, Patent Document 1).

  Also, when taking a picture, a counterweight is provided which starts and stops almost simultaneously in the opposite direction to the mirror retracted from the photographing optical path, and the mass of the counterweight is made larger than that of the mirror so that its movement distance is An anti-vibration device for a camera is known that is configured to cancel the shock so as to be shorter (see, for example, Patent Document 2).

  On the other hand, as a means for driving the mirror without using the energy storing force of the spring, there has been proposed a method in which the mirror is driven by a motor as a rotational drive source. As an example of such a mirror drive by a motor, there has been proposed a technical means for reducing shock by controlling mirror drive using an ultrasonic motor having excellent characteristics of quietness and high controllability among motors. (For example, see Patent Document 3).

In addition, an apparatus using an ultrasonic motor for driving a mirror is disclosed (for example, see Patent Document 4).
Japanese Patent Publication No.58-53323 Japanese Patent Laid-Open No. 5-273463 Japanese Patent Laid-Open No. 4-127135 JP-A-8-122915

  However, since the above-described ultrasonic motor is not suitable for high-speed driving, it has been difficult to shorten the release time lag or increase the number of frames that can be photographed per second. Further, when trying to drive the mirror at high speed, a mechanical speed increasing mechanism must be added to the ultrasonic motor, resulting in an increase in the size of the mechanism and a reduction in energy efficiency of the mechanism.

  Furthermore, in Patent Documents 1 to 4 described above, in order to increase the drive speed of the mirror, increase the shutter release time lag, and increase the number of frames that can be shot per second, the mirror bounce increases. Thus, it took time to retract the mirror to the mirror retracting position. Or, since an ultrasonic motor with a fundamentally low driving speed is used, there has been a problem that the driving speed cannot be increased.

  Furthermore, it goes without saying that when the drive speed of the mirror is increased, the occurrence of shock and noise associated with mirror drive, which has been a problem in the past, becomes a larger problem. In addition, it is difficult to stop the mirror with high accuracy.

  Accordingly, the present invention has been made in view of the above circumstances, and in a mirror driving system of a single-lens reflex camera, mirror driving that can reduce a mirror driving shock and can drive a mirror at high speed with high accuracy. The purpose is to provide a system.

  That is, according to the first aspect of the present invention, in a mirror driving system of a single-lens reflex camera, a movable mirror supported so as to be movable between a finder observation position and an exposure retracted position, and the movable mirror as the finder observation position. Alternatively, a mirror driving mechanism that moves the exposure mirror to the exposure retract position, a friction stop mechanism that stops the movable mirror at the viewfinder observation position or the exposure retract position by a friction force, and a release mechanism that releases the friction force of the friction stop mechanism. It is characterized by comprising.

  The invention according to claim 2 is the invention according to claim 1, wherein the release mechanism releases the frictional force by applying vibration to a frictional force generating portion of the friction stop mechanism. To do.

  According to a third aspect of the present invention, in the first aspect of the present invention, the friction stop mechanism includes a friction portion provided on the movable mirror and a fixed frame that holds the movable mirror movably. A friction spring having elasticity and having a friction sliding surface, and the friction spring has a friction sliding surface of the spring on the friction portion of the movable mirror near the stop position of the movable mirror. The movable mirror is stopped at a predetermined position by pressing.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the friction stop mechanism includes a vibrator in which a piezoelectric element is fixed to an elastic body.

  According to a fifth aspect of the present invention, in the first aspect of the invention, the friction stop mechanism generates a vibration for operating the movable mirror toward the viewfinder observation position or the exposure retreat position side when the vibration is applied. It is characterized by.

  The invention described in claim 6 is the invention described in claim 4, wherein the piezoelectric element is provided with an electrode for driving and an electrode for detecting vibration of the piezoelectric element. And

  The invention described in claim 7 is the invention described in claim 2, characterized in that a plurality of vibration modes are sequentially generated in the vibrator.

  The invention according to claim 8 is the invention according to claim 1, wherein the friction stop mechanism and the release mechanism are provided at least with respect to the exposure retracted position.

  The invention according to claim 9 is the invention according to claim 1, wherein the friction stop mechanism and the release mechanism are provided for at least one of the finder observation position and the exposure retract position. And

  According to the present invention, it is possible to provide a mirror driving system capable of reducing a mirror driving shock and driving a mirror with high speed and accuracy in a mirror driving system of a single-lens reflex camera.

  That is, according to the first aspect of the present invention, the mirror driving shock can be reduced, and the mirror can be driven with high accuracy at high speed.

  According to the second aspect of the present invention, the frictional force can be released quietly and reliably.

  According to the third aspect of the present invention, the movable mirror can be stopped with high accuracy with a simple configuration.

  According to the fourth aspect of the present invention, the movable mirror can be stopped with high accuracy with a simple configuration.

  According to invention of Claim 5, a mirror can be operated quietly and reliably.

  According to the sixth aspect of the present invention, the mirror can be reliably operated with a simple configuration.

  According to the seventh aspect of the invention, the vibration mode can be changed to reliably drive and stop the mirror at a desired position.

  According to the eighth aspect of the present invention, the mirror driving shock can be reduced and the mirror can be driven with high accuracy at high speed.

  According to the ninth aspect of the present invention, the mirror driving shock can be reduced and the mirror can be driven with high accuracy at high speed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view schematically showing an internal structure of a part of an electronic camera according to an embodiment of the present invention.

  In FIG. 1, an electronic camera 1 according to the present embodiment includes a camera main body 11 and a lens barrel 12 that are configured separately, and the camera main body 11 and the lens barrel 12 are: They are configured to be detachable from each other.

  The lens barrel 12 is configured by holding therein a photographic optical system 12a including a plurality of photographic lenses and their driving mechanisms. The photographing optical system 12a transmits a light beam from the subject so that an image of the subject formed by the subject light beam is formed at a predetermined position (on a photoelectric conversion surface of an image sensor 44 described later). For example, it is composed of a plurality of optical lenses. The lens barrel 12 is disposed so as to protrude toward the front surface of the camera body 11.

  The lens barrel 12 is the same as that generally used in conventional cameras and the like. Therefore, the detailed description of the configuration is omitted.

  The camera body 11 includes various components and the like, and is an imaging optical device that is a connecting member for detachably mounting the lens barrel 12 that holds the imaging optical system 12a. This is a so-called single-lens reflex camera having a system mounting portion (also referred to as a photographing lens mounting portion) provided on the front surface thereof.

  That is, an exposure opening having a predetermined aperture capable of guiding the subject light flux to the inside of the camera main body 11 is formed at a substantially central portion on the front side of the camera main body 11. A photographing optical system mounting portion (not shown) is formed at the peripheral edge of the exposure opening.

  On the outer surface side of the camera body 11, the above-described photographing optical system mounting portion is disposed on the front surface, and various kinds of operations for operating the camera body 11 at predetermined positions such as an upper surface portion and a back surface portion. An operation member, for example, a release button 14 for generating an instruction signal for starting a photographing operation is provided. Since these operation members are not directly related to the present invention, the illustration and description of the operation members other than the release button 14 are omitted in order to avoid complication of the drawing.

  As shown in FIG. 1, the camera body 11 includes a plurality of components such as a finder device 15, a shutter unit 16, an image sensor unit 17, and a main circuit board 18. A circuit board (only the main circuit board 18 is shown in FIG. 1) and the like are arranged at predetermined positions.

  The finder device 15 is provided so as to form a desired subject image formed by the photographing optical system 12a at a predetermined position different from the photoelectric conversion surface of the image pickup device 44 (see FIG. 2). An observation optical system is configured.

  The viewfinder device 15 includes a quick return mirror 15a, a pentaprism 15b, and an eyepiece lens 15c.

  The quick return mirror 15a can be guided to the observation optical system side by bending the optical axis of the subject luminous flux transmitted through the photographing optical system 12a. The pentaprism 15b receives the light beam emitted from the quick return mirror 15a and forms an erect image. The eyepiece 15c is used to form an image having an optimum form for magnifying and observing the image formed by the pentaprism 15b.

  The quick return mirror 15a is configured to be movable between an exposure retracting position retracted from the optical axis of the photographing optical system 12a and a predetermined position on the optical axis, and in a normal state, the photographing optical system 12a. The optical axis is arranged at a predetermined angle with respect to the optical axis, for example, an angle of 45 degrees. As a result, the subject luminous flux transmitted through the photographing optical system 12a is bent by the quick return mirror 15a when the electronic camera 1 is in a normal state, and the pentagon disposed above the quick return mirror 15a. Reflected toward the prism 15b. That is, this is the finder observation position of the quick return mirror (movable mirror) 15a.

  On the other hand, while the electronic camera 1 is performing a photographing operation, during the actual exposure operation, the quick return mirror 15a is moved to a predetermined position retracted from the optical axis of the photographing optical system 12a. It has become. As a result, the subject luminous flux is guided to the image sensor 44 side, and irradiates the photoelectric conversion surface.

  The shutter unit 16 controls the irradiation time of the subject light beam onto the photoelectric conversion surface of the image sensor 44, and includes a shutter mechanism.

  The image pickup device unit 17 includes the image pickup device 44 that obtains an image signal corresponding to a subject image formed based on the shutter portion 16, and a subject light beam including the shutter portion 16 and transmitted through the photographing optical system 12 a, and the image pickup device 44. It is comprised by the assembly which consists of dust-proof filter 19 etc. which are arrange | positioned in the predetermined position of the front side of this photoelectric conversion surface, and prevent adhesion of the dust etc. to the said photoelectric conversion surface.

  The main circuit board 18 is mounted with various electric members constituting an electric circuit of an image signal processing circuit (not shown) that performs various signal processing on the image signal acquired by the image sensor 44. Yes.

  The shutter unit 16 is the same as that generally used in conventional cameras and the like, such as a focal plane type shutter mechanism and a drive circuit for controlling the operation of the shutter mechanism. . Therefore, the detailed description of the configuration is omitted.

  FIG. 2 is a block diagram schematically showing mainly the electrical configuration of the electronic camera.

  In FIG. 2, this electronic camera is mainly composed of a lens unit 20 as an interchangeable lens and a body unit 30 as a camera body, and a desired lens unit 20 is disposed on the front surface of the body unit 30. It is set to be detachable.

  The lens unit 20 is controlled by a lens control microcomputer (hereinafter referred to as Lμcom) 21. On the other hand, the body unit 30 is controlled by a body control microcomputer (hereinafter referred to as “Bμcom”) 31.

  The Lμcom 21 and Bμcom 31 are electrically connected via the communication connector 3 so as to be communicable at the time of merging. As a camera system, Lμcom 21 operates in cooperation with Bμcom 31 in a dependent manner.

  In the lens unit 20, a photographing lens 22 and a diaphragm 23 are provided. The photographing lens 22 is driven by a DC motor (not shown) that exists in the lens driving mechanism 24. The diaphragm 23 is driven by a stepping motor (not shown) existing in the diaphragm drive mechanism 25. The Lμcom 21 controls each of these motors according to the command of the Bμcom 31.

  On the other hand, the following components are arranged in the body unit 30 as shown.

  For example, a single-lens reflex structural member (quick return mirror 15a, pentaprism 15b, eyepiece 15c, sub mirror 32) as an optical system, a focal plane shutter 16a on the optical axis, and a reflected light beam from the sub mirror 32 In response, an AF sensor unit 33 for automatic ranging is provided.

  In the body unit 30, an AF sensor driving circuit 34 for driving and controlling the AF sensor unit 33, a mirror driving mechanism 35 for driving and controlling the quick return mirror 15a, and a front curtain and a rear curtain of the shutter 16a are provided. A shutter charge mechanism 36 that charges a driving spring, a shutter control circuit 37 that controls the movement of the front curtain and the rear curtain, and a photometric circuit 38 that performs photometric processing based on the light flux from the pentaprism 15b are provided. .

  Vibrating brakes 40a and 40b that act on the quick return mirror 15a to brake or release the operation are provided in the vicinity of the quick return mirror 15a. Among these, the vibration brake 40a is provided for stopping the quick return mirror 15a in the optical path. On the other hand, the vibration brake 40b is provided to stop the quick return mirror (movable mirror) 15a at the exposure retreat position outside the optical path.

  The vibration brakes 40a and 40b have piezoelectric elements 41a and 41b, respectively. Then, a periodic voltage having a predetermined frequency is applied from the vibration brake drive circuit 42 at a predetermined timing, whereby the frictional force applied to the quick return mirror 15a is controlled as will be described in detail later. Thereby, the quick return mirror 15a can be quickly stopped at a predetermined position.

  The vibration brake drive circuit 42 is an electrical means for applying vibration to the piezoelectric element. The vibration brakes 40a and 40b and the vibration brake drive circuit 42 constitute a friction stop mechanism and a release mechanism.

  On the optical axis, a CCD unit (imaging element) 44 for photoelectrically converting the subject image that has passed through the optical system is provided as a photoelectric conversion element. Further, a dustproof glass 45 as an optical element is disposed between the CCD unit 44 and the photographing lens 12a, and the CCD unit 44 is protected by the dustproof glass 45. A temperature measuring circuit (not shown) for measuring the temperature around the CCD unit 44 is provided in the vicinity of the dust-proof glass 45.

  The camera system also includes an image processing controller that performs image processing using a CCD interface circuit 46 connected to the CCD unit 44, a liquid crystal monitor 47, an SDRAM 48 provided as a storage area, a flash ROM 49, a recording medium 50, and the like. 51 is provided so that an electronic recording display function can be provided together with an electronic imaging function.

  As other storage areas, for example, a non-volatile memory 53 made of EEPROM is provided as a non-volatile storage means for storing predetermined control parameters necessary for camera control so as to be accessible from the Bμcom 31.

  Further, the Bμcom 31 is provided with an operation display LCD 54 and a camera operation switch (SW) 55 for notifying the user of the operation state of the camera by display output. The camera operation switch 55 is constituted by a switch group including operation buttons necessary for operating the camera, such as a release switch, a mode change switch, and a power switch.

  Further, the camera body 30 is provided with a battery 57 as a power source, and a power circuit 58 for converting the voltage of the power source into a voltage required by each circuit unit constituting the camera system and supplying it. ing.

  In the electronic camera configured as described above, each unit operates as follows.

  The image processing controller 46 controls the CCD interface circuit 46 in accordance with a command from the Bμcom 31, and image data is taken in from the CCD unit 44. This image data is converted into a video signal by the image processing controller 46 and output and displayed on the liquid crystal monitor 47. The user can confirm the captured image from the display image on the liquid crystal monitor 47.

  The SDRAM 48 is a memory for temporarily storing image data, and is used as a work area when image data is converted. The image data is set to be stored in the recording medium 50 after being converted into JPEG data.

  It is more preferable for dust prevention that the CCD unit 44 is integrally housed in a case having the dust-proof glass 45 as one surface and surrounded by a frame as shown by a broken line in the drawing.

  The mirror drive mechanism 35 is a mechanism for driving the quick return mirror 15a UP (up) position and DOWN (down) position. When the quick return mirror 15a is in the DOWN position, the light beam from the photographing lens 22 is divided and guided to the AF sensor unit 33 side and the pentaprism 15b side.

  The output from the AF sensor in the AF sensor unit 33 is transmitted to the Bμcom 31 via the AF sensor driving circuit 34 and a known distance measurement process is performed.

  In addition, the user can view the subject from the eyepiece lens 15c adjacent to the pentaprism 15b. On the other hand, a part of the light beam that has passed through the pentaprism 15b is guided to a photosensor (not shown) in the photometry circuit 38, and a well-known photometry process is performed based on the amount of light detected here.

  Next, the operation of the vibration brake described above will be described with reference to FIGS.

  3 is a perspective view showing the structure of the main part of the quick return mirror 15a and its drive mechanism, FIG. 4 is a diagram for explaining the stopped state of the finder observation position and the exposure retract position of the quick return mirror 15a, FIG. FIG. 7 is a cross-sectional view showing a specific configuration of a vibration brake, FIG. 5B is a view for explaining an example of bending vibration of a brake plate, and FIG.

  The mirror 61 is fixed to a mirror holding frame 62, and the mirror 61 and the mirror holding frame 62 constitute a quick return mirror 15a. A fitting hole 63 is formed at one end of the mirror holding frame 62. The fitting hole 63 is for fitting on the mirror shaft 64 fixed to the fixed frame 62 to hold the quick return mirror 15a on the fixed frame 65 in a freely rotatable manner.

  Although only one fitting hole 63 is shown in FIG. 3, another fitting hole is actually formed in the depth direction of FIG. 3, and these two fitting holes are mirrors. The mirror 61 is held by fitting with the shaft 64.

  A shaft 68 is formed in the vicinity of the fitting hole 63 of the mirror holding frame 62, and a mirror driving roller 69 is rotatably held on the shaft 68.

  On the other hand, a drive lever shaft 70 is fixed to the fixed frame 65. Further, a mirror drive lever 71 is rotatably held on the drive lever shaft 70. The mirror driving roller 69 is pressed against the cam 72 of the mirror driving lever 71 by a roller spring 73 made of a leaf spring fixed to the mirror driving lever 71.

  Thus, when the mirror drive lever 71 rotates in a predetermined direction, the mirror drive roller 69 operates along the cam 72 and the mirror holding frame 62 rotates around the mirror shaft 64.

  The mirror drive lever 71 receives a force in a direction to rotate the mirror holding frame 62 toward the viewfinder observation position by a drive lever spring 75 described later. The drive lever spring 75 is held by the drive lever shaft 70, one end of which is hung on a protrusion 76 formed on the fixed frame 65, and the other end is hooked on a protrusion 77 formed on the mirror drive lever 71. It has a configuration.

  On the other hand, the drive lever roller 81 rotatably held on the shaft 80 fixed to one end of the mirror drive lever 71 is in contact with the bending of the cam lever 82. The cam lever 82 is rotatably held by a cam lever shaft 83 fixed to the fixed frame 65.

  The rotation of the motor 85 for driving the quick return mirror 15a is reduced from the pinion gear 86 by a gear reduction system including the gear A87, the gear B88, and the gear C89, and the cam 90 integrated with the gear C89 is rotated. The cam 90 is in contact with a cam roller 93 rotatably held on a shaft fixed to one end of the cam lever 82. The cam 90 rotates and swings with respect to the cam lever shaft 83 as the cam 90 rotates.

  As the cam 90 rotates, the cam lever 82 swings, the mirror drive lever 71 swings with respect to the drive lever shaft 70, and the mirror holding frame 62 swings between the finder observation position and the exposure retracting position.

  The finder observation position of the mirror holding frame 62 is a position where the notch 90 a formed in the cam 90 is stopped when the sensor 94 detects it. If the position of the mirror 61 is not accurately maintained at the finder observation position, the finder image may be blurred. For this reason, the mirror holding frame 62 is configured to stop against the stopper A95 provided on the fixed frame. In order to stop the quick return mirror 15a accurately at the viewfinder observation position, the vibration brake 40a as a vibrator is fixed to the fixed frame 65.

  A specific configuration of the vibration brake 40a is shown in FIG.

  A piezoelectric element 101 polarized in the plate thickness direction is in contact with one surface side of a brake plate 100 made of, for example, a stainless steel for spring or a phosphor bronze material for spring with little vibration damping. On the other surface side of the brake plate 100, a friction sheet 103 that is pressed against the brake pin (friction portion) 102 by the spring force of the brake plate (friction spring, elastic body) 100 is fixed.

  On the other hand, one end of the brake plate 100 is fixed by screws 105 with a vibration-proof sheet 104 having vibration-proof properties such as rubber that hardly transmits vibration to the fixed frame 65 interposed therebetween. Further, the brake pin 102 receives a sudden friction brake by coming into contact with the friction sheet 103, whereby the mirror holding frame 62 can be quickly stopped. The friction sheet may be a composite resin material used as a brake lining material, an inorganic material such as ceramic, or a material obtained by coating these materials on a brake plate.

  When the quick return mirror 15a is driven to the viewfinder observation position side, immediately before driving the motor 85, the piezoelectric substrate of the vibration brake 40a is contacted with the flexible substrate 106a and the flexible substrate 106b which is in contact with the brake plate 100 as a conductor. When the frequency voltage is applied, the piezoelectric element 10 expands and contracts in the longitudinal direction of the brake plate 100, and the brake plate 100 undergoes bending vibration (see FIG. 5B).

  As shown in FIG. 5B, when contact is made in the vicinity of the vibration antinode, the contact between the brake pin 102 and the friction sheet 103 becomes intermittent, and the friction time is reduced by reducing the contact time. Accordingly, if the motor 85 is operated in this state, the mirror holding frame 62 can be easily moved by the force of the drive lever spring 75.

  FIG. 5B shows the operation of the surface of the friction sheet 103, and the illustrated arrow represents the movement of the mass point on the surface of the friction sheet 103. Due to the movement of the mass point, a component in the direction of moving the brake pin 102 to the exposure retreat position side is generated on the free end side of the brake plate 100 from the antinode of vibration, and also plays a role of assisting the force of the drive lever spring 75.

  In addition, if the brake pin 102 is set so that the viewfinder observation position comes to a position slightly closer to the fixed end of the brake plate 100 from the vibration antinode, the mirror holding frame 62 is moved to the stopper A95 when the vibration brake 40a is operated. Vibration acts in the direction of application, and the vibration brake 40a can be used as an actuator, so that the position of the quick return mirror 15a can be accurately set.

  At this time, the force acting on the brake pin 120 is extremely weak, and the frictional force is much smaller than when the operation of the vibration brake 40a is stopped, and the mirror holding frame 62 can be operated by the force of the drive lever spring 75. Furthermore, it is easy to set the movement component of the stopper A95 generated by one vibration to 1 μm or less, and the position of the mirror 61 can be accurately controlled.

  A signal having a frequency that causes the brake plate 100 to generate a bending resonance vibration as shown in FIG. 5B is preferably applied to the piezoelectric element 101. In the vibration state, unless resonance is used, it is necessary to apply a very high voltage in order to increase the amplitude of vibration. Further, when the frequency signal is in an ultrasonic region (20 kHz or more), it becomes an extremely quiet brake that does not generate noise.

  The vibration brake 40b is configured to have the same function as the vibration brake 40a described above, and is provided to control the position of the quick return mirror 15a at the exposure retreat position. A stopper B96 for stopping the quick return mirror 15a at the exposure retracted position is provided in the vicinity of the vibration brake 40b. 3 is a flexible substrate constituting the vibration brake 40b.

  When the vibration brake 40b is used as a brake, the maximum friction force can be applied without being operated. However, if the vibration amplitude of the vibration brake is controlled, the friction force can be finely controlled, and the quick return mirror 15a. Can be stopped accurately and quickly.

  For example, as shown in FIG. 5C, when the vibration of the higher-order resonance bending mode is generated with the same power, the vibration amplitude of the vibration brake is reduced, and the contact time between the brake pin 102 and the friction sheet 103 is increased. The frictional force is increased. Therefore, the stop time of the quick return mirror 15a is shortened. Conversely, if the vibration amplitude is increased, the frictional force is reduced and the stop time is lengthened. Reducing the vibration amplitude of the vibration brake can be easily realized by lowering the applied voltage to the piezoelectric element or shifting the frequency of the applied voltage from resonance.

  Further, by changing the vibration mode, it is possible to change the position of the node of the bending vibration as shown in FIG. 5B or 5C, as shown in FIG. 5B. Since the vibration acts in the direction of moving the brake pin in the direction of the node between the nodes of vibration, the brake pin can be moved in a predetermined direction. Thus, if a plurality of vibration modes are used, the position of the brake pin can be precisely controlled by the vibration of the vibration brake.

  Next, based on the circuit diagram of the vibration brake drive circuit shown in FIG. 6 and the time chart of FIG. 7, the drive of the vibration brake and its operation and control in this embodiment will be described.

  The vibration brake drive circuit 42 has a circuit configuration as shown in FIG. 6, and waveform signals (Sig1 to Sig6) shown in the time chart of FIG. Based on this, it is controlled as follows.

  That is, as shown in FIG. 6, the anti-vibration brake drive circuit 42 includes an N-ary counter 121, a ½ divider circuit 122, an inverter 123, a plurality of MOS transistors Q1, Q2, Q3, and a transformer 124. A resistor R1, an A / D converter 125, a first electrode A130 of the piezoelectric element 101, a second electrode B131 aligned therewith, a diode D1, resistors R2, R3, and a capacitor C1. Yes.

  The transformer 124 is configured such that a signal (Sig4) having a predetermined period is generated on the secondary side of the transformer 124 by the on / off switching operation of the transistor Q2 and the transistor Q3 connected to the primary side. . Based on the signal of this predetermined period, the piezoelectric element 130 having the two electrodes A and B is driven variously, and an effective resonance frequency is found to effectively resonate the vibration brake 40a. . Details of this will be described later.

  The vibration brake drive circuit 42 is controlled by the Bμcom 31 through the two IO ports P_PwCont and IO port D_NCnt provided as control ports and the clock generator 31a existing inside the Bμcom 31 as follows.

  From the clock generator 31 a, a pulse signal (basic clock signal) is output to the N-ary counter 121 at a frequency sufficiently faster than the signal frequency applied to the piezoelectric element 101. This output signal is the signal Sig1 having the waveform shown in the time chart of FIG. This basic clock signal is input to the N-ary counter 121.

  The N-ary counter 121 counts the pulse signal and outputs a count end pulse signal every time it reaches a predetermined value “N”. That is, the basic clock signal is divided by 1 / N. This output signal is a signal Sig2 having a waveform shown in the time chart of FIG.

  The divided pulse signal does not have a high and low duty ratio of 1: 1. Therefore, the duty ratio is converted to 1: 1 through the ½ divider circuit 122. The converted pulse signal corresponds to the signal Sig3 having the waveform shown in the time chart of FIG.

  In the High state of the converted pulse signal, the MOS transistor Q2 to which this signal is input is turned on. On the other hand, this pulse signal is applied to the transistor Q3 via the inverter 123. Accordingly, in the low state of the pulse signal, the transistor Q3 to which this signal is input is turned on. When the transistors Q2 and Q3 connected to the primary side of the transformer Q3 are alternately turned on, a signal having a cycle such as the signal Sig4 shown in the timing chart of FIG. 7 is generated on the secondary side.

  The winding ratio of the transformer 124 is determined from the output voltage of the unit of the power supply circuit 58 and the voltage necessary for driving the piezoelectric element 101. The resistor R1 is provided to limit the excessive current flowing through the transformer 124.

  When driving the piezoelectric element 101, the transistor Q <b> 1 is in an on state, and a voltage must be applied from the unit of the power supply circuit 58 to the center tap of the transformer 124. In the figure, the on / off control of the transistor Q1 is performed via the P_PwCont of the IO port. The set value “N” of the N-ary counter 121 can be set from the IO port D_NCnt. Therefore, the Bμcom 31 can arbitrarily change the drive frequency of the piezoelectric element 101 by appropriately controlling the set value “N”.

At this time, the frequency can be calculated by the following equation.
N: Set value to counter
fpls: frequency of the output pulse of the clock generator,
fdrv: frequency of a signal applied to the piezoelectric element,
fdrv = fpls / 2N (1)
The calculation based on this equation is performed by the CPU of Bμcom31.

  The electrode B131 is an electrode of a piezoelectric element for detecting the vibration state of the brake plate 100 to which the friction sheet 103, the piezoelectric element 101, and the flexible substrate 106a are fixed (see FIGS. 8A and 8B). An alternating voltage (monitor signal) corresponding to the vibration state of the brake plate 100 is generated from the electrode B131. This is the signal Sig5 on the time chart of FIG.

  The diode D1 connected to the electrode B131 is provided for half-wave rectification of the monitor signal. An envelope of the monitor signal is formed by the resistors R2 and R3 and the capacitor C1 following the diode D1. The optimum value of the time constant determined by the detection circuit including the resistors R2 and R3 and the capacitor C1 varies depending on the vibration frequency of the brake plate 100.

  The brake plate 100 of the present embodiment can be driven in a plurality of resonance modes (first and second drive modes). When the drive frequencies in these multiple resonance modes are greatly different, it is necessary to adopt a circuit configuration so that the time constant can be changed. The monitor signal is reduced to a level that can be input to the A / D converter 125 by the resistors R2 and R3. This signal is the signal Sig6 on the time chart of FIG.

  This signal is converted into digital data by the A / D converter 125 and read from the IO port D_DACin of the Bμcom 31. The Bμcom 31 may change the value set in the N-ary counter 121 so that the monitor signal becomes the maximum level. When the brake plate 100 is driven with the value (resonance frequency) of the N-ary counter 121 indicating the maximum level, the vibration brake can be operated efficiently.

  Next, the control performed by the above-described Bμcom 31 will be specifically described.

  FIG. 9 is a flowchart for explaining the operation of the camera sequence under the control of Bμcom 31.

  When a power switch (not shown) of the camera is turned on, the operation of Bμcom 31 is started. First, in step S1, processing for starting the electronic camera is executed. Here, the power supply circuit 58 is controlled to supply power to each circuit unit constituting the electronic camera. In addition, initial setting of each circuit is performed.

  Next, in step S2, the subroutine “resonance point detection operation” is called and executed. In this subroutine, a driving frequency (resonance frequency) suitable for efficiently vibrating the brake plate 100 is detected. This frequency data is stored in a memory area of a predetermined address of Bμcom31. The details of the subroutine “resonance point detection operation” will be described later.

  In step S3, the state of the lens unit 20 is detected by performing a communication operation with the Lμcom 21. This detection operation is executed periodically. In steps S4 and S5, it is determined whether the lens unit 20 is attached to or removed from the body unit 30.

  Here, when it is detected that the lens unit 20 is attached to the body unit 30, the process proceeds to step S6, and the control flag F_Lens is reset. On the other hand, when it is detected that the lens unit 20 is detached from the body unit 30, the process proceeds to step S7, and the control flag F_Lens is set. This control flag indicates “1” when the lens unit 10 is attached to the body unit 30 of the camera, and indicates “0” when the lens unit 10 is removed.

  Next, in step S8, the state of the camera operation switch 55 is detected. In step S9, it is determined whether or not a first release switch (1st release SW) (not shown) which is one of the camera operation switches 55 has been operated. If the first release switch is on, the process proceeds to step S10. If the first release switch is off, the process proceeds to step S3.

  In step S10, the luminance information of the subject is obtained from the photometry circuit 38. From this information, the exposure time (Tv value) of the CCD unit 44 and the aperture setting value (Av value) of the photographing lens 22 are calculated. Further, in step S11, detection data of the AF sensor unit 33 is obtained via the AF sensor driving circuit 34. Based on this data, the amount of focus shift is calculated.

  Here, in step S12, the state of F_Lens is determined. If the flag indicating the state of F_Lens is “0”, it means that the lens unit 20 does not exist. Therefore, the subsequent photographing operation from step S13 cannot be executed. Therefore, in this case, the process proceeds to step S3. On the other hand, if the flag indicating the state of F_Lens is “1”, the process proceeds to step S13.

  In step S13, the amount of focus shift is transmitted to Lμcom 21, and the driving of the photographing lens 22 based on this amount of shift is commanded.

  In step S14, it is determined whether or not a second release switch (2nd release SW) (not shown), which is one of the camera operation switches 55, has been operated. When the second release switch is turned on, a predetermined photographing operation after step S15 is performed. However, when the second release switch is OFF, the process proceeds to step S3.

  In step S15, the Av value is transmitted to the Lμcom 21, and the diaphragm 23 is driven. Next, in step S16, the subroutine “vibration braking operation” is called and executed. Here, the vibration brake 40a is operated, and the frictional force of the vibration brake 40a is released for a predetermined time. The details of this subroutine “vibration brake operation” will be described later.

  In step S17, the quick return mirror 15a is moved from the viewfinder observation position to the exposure retract position (UP position). In step S18, the front curtain of the shutter 16a is started, and in step S19, the image processing controller 51 is instructed to execute an imaging operation. Here, when the exposure to the CCD unit 44 is completed for the time indicated by the Tv value, the rear curtain running of the shutter 16a is started in step S20.

  Next, in step S21, the vibration brake 40b is operated and the frictional force is released for a predetermined time. Further, in step S22, the quick return mirror 15a is moved from the exposure retracted position to the finder observation position (Down position). In parallel with this, the shutter 16a is charged.

  In step S23, the Lμcom 21 is instructed to return the diaphragm 23 to the open position. In step S24, the image processing controller 51 is instructed to record the captured image data on the recording medium 50. When the recording of the image data ends, the process proceeds to step S3.

  Here, the resonance frequency detection operation in the two types of vibration modes in the subroutine “resonance point detection operation” will be described with reference to FIGS. 10 to 12.

  The range in which the resonance frequency exists can be predicted depending on the characteristics (for example, shape, composition, support method, etc.) of the vibration brake. Therefore, the resonance point should be detected by applying vibration to the vibration brake within this range. Otherwise, the detection operation will take longer than necessary.

  If the detection range is not assumed, there is a risk of detecting the resonance frequency in a higher-order resonance mode other than the intended vibration mode.

  Therefore, in this embodiment, parameters necessary for the detection operation of the resonance frequency are stored in advance in the EEPROM 53 having a plurality of areas shown in the memory map of FIG. As a "corresponding control parameter". The details of the control parameter values corresponding to the vibration mode 1 are stored as the values shown in FIG. For example, StartOffset indicates the reading start position of this table.

  Similarly, the details of the control parameter values corresponding to the vibration mode 1 are stored as values shown in FIG. 12A as the “vibration mode 1 frequency correction table”. Such a data table indicates values set in the N-ary counter 121 when the vibration brake is driven in the vibration mode 1. This table is calculated on the assumption that the clock generator 31a outputs a pulse signal having a frequency of 40 (MHz). This can be calculated by using the above-described equation (1).

  StopOffset indicates the read end position of the vibration mode 1 compatible frequency correction table. When the drive frequency is changed in the range from StartOffset to StopOffset, the vibration brake vibrates in vibration mode 1 with the value of any table.

  StepTime indicates the time to drive at one frequency when the drive frequency is changed. This is determined in consideration of the stabilization time of the vibration brake drive circuit 42. Even when the driving frequency is changed, the vibration of the brake plate 100 does not immediately follow. If it does not follow, the monitor signal output cannot be relied upon.

  ADwait is a parameter that determines the frequency at which the monitor signal is A / D converted. M1OscTime, which is determined to be an appropriate value according to the resonance frequency of the brake plate 100, vibrates the brake plate 100 at the detected frequency. Shows time. This vibration time is set to a time longer than the time when the brake pin 102 of the mirror holding frame 62 comes to the position where it is out of the range of action of the vibration brake.

  The above are the control parameters in the vibration mode 1.

  Details of the control parameters corresponding to the vibration mode 2 are shown in FIG. The details of the frequency correction table corresponding to vibration mode 2 are shown in FIG. 12B, and are parameters having the same configuration as that of vibration mode 1, which are basically the same, and will not be described.

  Next, details of the subroutine “resonance point detection operation” in step S2 in the flowchart of FIG. 9 will be described with reference to the flowcharts of FIGS. 10 to 12 and FIG.

  First, in step S31, four control parameters (StartOffset, StopOffset, StepTime, ADwait) are read from the EEPROM 53. In step S32, Address M1 + StartOffset is set as the read start address of the EEPROM 53, and Address M1 + StopOffset is set as the read end address. Here, Address M1 indicates the head address of the vibration mode 1 compatible frequency correction table.

  If the reading start position (StartOffset) is set to “3” and the reading end position (StopOffset) is set to “9”, the preset value “N” in the area indicated by * 1 to * 2 in FIG. Is set in the N-ary counter 121. That is, the frequency at which the output of the monitor signal is maximized is detected from the frequencies f1, f2, f3,..., F7.

  In step S3, # 0, which is the minimum value of the monitor signal, is set for convenience in the memory D_ADMAX reserved for temporarily storing the maximum value of the monitor signal.

  In subsequent step S4, a preparatory operation for driving the piezoelectric element 101 is performed. That is, the IO port P_PwCont is controlled to turn on the transistor Q1. Furthermore, the output of a pulse signal is started from the clock generator 31a. If the data extracted from the table is set in the N-ary counter 121 in this state, the piezoelectric element 101 can be driven at a desired frequency.

  In step S35, the preset value (N) is read from the set address of the EEPROM 53. Further, a preset value read out from the IO port D_NCnt to the N-ary counter 121 is set. In step S36, the system waits for a predetermined time until the frequency driving circuit is stabilized.

  In step S37, Steptime is set in the timer counter 1, and a count operation of a timer (not shown) in the Bμcom 31 is started. For example, as shown in FIG. 11A, when Steptime is stored, 2 (msec) is set in the timer counter 1.

  Next, in step S38, # 0 is set in the memory area D_ADSUM reserved for temporarily storing the addition data of the A / D converter 125. Further, # 0 is set in the memory D_ADcount reserved for counting the number of operations of the A / D converter 125.

  In step S39, ADwait is set in the timer counter 2 (not shown) in the Bμcom 31, and the count operation is started. For example, as shown in FIG. 11A, when ADwait is stored, 80 (μsec) is set in the timer counter 2.

  In step S40, the A / D converter 125 is used to acquire the A / D conversion value of the monitor signal. In step S41, the A / D conversion value of the monitor signal is added to the memory area D_ADSUM. Further, the memory area D_ADcount is incremented (1 is added).

  In step S42, the process waits until the count operation of the timer counter 2 is completed. In a succeeding step S43, it is determined whether or not the counting operation of the timer counter 1 is finished. In step S43, if it has not been completed yet, the process proceeds to step S39 again to measure the monitor signal. On the other hand, if completed, the process proceeds to step S44.

  In step S44, an average value of the A / D conversion values is obtained from the memory areas D_ADSUM and D_ADcount. The average value is stored in the memory area D_ADAVE reserved for recording the average value. D_ADAVE indicates the level of the monitor signal at the current drive frequency.

  In step S45, the contents of D_ADAVE and D_ADMAX are compared. If the content of D_ADAVE is larger than the content of D_ADMAX, the process proceeds to step S46, and if smaller, the process proceeds to step S50.

  In step S46, the contents of D_ADAVE are moved into D_ADMAX. Here, the old maximum value is discarded, and the value measured this time is stored as the maximum value of the monitor signal.

  In step S47, the current vibration mode is determined. If the monitor signal is being measured in vibration mode 1, the process proceeds to step S48. If the monitor signal is currently being measured in the vibration mode 2, the process proceeds to step S49.

  In step S48, the current address of the EEPROM 53 is stored in D_M1resonant. D_M1resonant is an area secured on the memory to store the address for vibration mode 1.

  In step S49, the current EEPROM address is stored in D_M2resonant. This D_M2resonant is an area secured on the memory in order to store the address for vibration mode 2.

  These values of D_M1resonant and D_M2resonant are used when the vibration brake is operated.

  In step S50, it is determined whether or not the monitor signal measurement has been completed up to the drive frequency indicated by the EEPROM read end address. If it has not been completed yet, the process proceeds to step S51. If it has been completed, the process proceeds to step S52.

  In step S51, the read address of the EEPROM 53 is incremented. Thereafter, the process proceeds to step S35.

  On the other hand, in step S52, processing for stopping the driving operation is performed. The transistor Q1 is turned off and the operation of the clock generator 31a is stopped.

  Then, in step S53, it is determined whether or not the resonance point detection operation in vibration mode 1 and vibration mode 2 has been completed. Here, if the detection operation is completed, the routine is exited. On the other hand, when only the vibration mode 1 is completed, the process proceeds to step S54 in order to detect the resonance frequency in the vibration mode 2.

  In addition, since the operation | movement of step S54 and S55 is fundamentally the same as step S31 and 32 mentioned above, description here is abbreviate | omitted.

  And in order to detect a resonant frequency, it transfers to said step S33.

  In this subroutine, preset values are read from the frequency correction table within a range defined by two parameters (StartOffset, StopOffset). Then, the glass plate is driven using all of the preset values, and the level of the monitor signal is measured.

  FIG. 14 shows the relationship between the frequency and the amplitude of the brake plate. In the figure, it is assumed that * 3 indicates the characteristic of the resonance mode 1 described above.

  In this routine, the monitor signal level is measured at the frequencies (preset values) f1, f2, f3,..., F7 shown in FIG. The resonance frequency in the characteristic of * 3 is fc. This fc corresponds to f4. In this routine, monitor signals are measured while f1, f2, f3, and f4 are sequentially changed in drive frequency. Then, even after the resonance frequency fc is passed, the driving is continued in order of f5, f6, and f7.

  In the above f1 to f4, the monitor signal is in an increasing direction. Then, the monitor signal changes in a decreasing direction from f5. Therefore, if the change of the monitor signal from the increasing direction to the decreasing direction is detected, there is no need to drive with the frequencies of f6 and f7. If the frequency change range is wide, it is desirable to create a control program as shown here in order to shorten the detection time of the resonance frequency.

  Next, the subroutine “vibration brake operation” of step S16 in the flowchart of FIG. 9 will be described with reference to the flowchart of FIG.

  In this subroutine, the piezoelectric element 101 is set to be driven so that the brake plate 100 is resonated in the two modes of vibration mode 1 and vibration mode 2 described above. When the vibration mode of the vibration brake 100 is changed, the magnitude and direction of the frictional force of the vibration brake 100 can be controlled. Whether to use one vibration mode or a plurality of vibration modes may be selected according to the purpose of control.

  Therefore, first, in step S61, M10scTime is read from the vibration mode 1 compatible control parameter of the EEPROM 53, and M20scTime is read from the vibration mode 2 compatible control parameter. Next, in step S62, a preparatory operation for driving the piezoelectric element 101 is performed. The P_PwCont of the IO port is controlled to turn on the transistor Q1.

  Furthermore, the output of a pulse signal is started from the clock generator 31a. In this state, if the data extracted from the table of the EEPROM 53 is set in the N-ary counter 121, the piezoelectric element 101 can be driven at a desired frequency.

  In step S63, the preset value (N) is read from the address of the EEPROM 53 indicated by D_M1resonant. This value is set in the N-ary counter 121. Accordingly, the brake plate 100 is driven at the resonance frequency of the vibration mode 1 by the vibration brake drive circuit 42.

  In step S64, M10scTime is set in the timer counter 1, and the count operation is started. For example, as shown in FIG. 11A, when M10scTime is stored, 200 (msec) is set in the timer counter 1.

  In step S65, the process waits until the count operation of the timer counter 1 is completed.

  Thus, the operation in the vibration mode 1 is completed. Further, the brake plate 101 is vibrated in the vibration mode 2 in order to reliably perform the operation.

  In step S66, the preset value (N) is read from the address of the EEPROM 53 indicated by D_M2resonant. This value is set in the N-ary counter 121. Accordingly, the brake plate 100 is driven at the resonance frequency of the vibration mode 2 by the vibration brake drive circuit 42.

  In step S67, M20scTime is set in the timer counter 2, and the count operation is started. For example, as shown in FIG. 11B, when M20scTime is stored, 100 (msec) is set to the timer counter 2.

  In step S68, the process waits until the count operation of the timer counter 2 is completed. In step S69, a process for stopping the driving operation is performed. That is, the transistor Q1 is turned off and the operation of the clock generator 31a is stopped.

  Thereafter, the routine is exited.

  Note that it is very difficult to predict variations in the resonance frequency of the brake plate 100 at the design stage of such an electronic camera. Therefore, it should be possible to set control parameters for determining the drive frequency of the piezoelectric element 101 after the electronic camera is completed. Therefore, as described above, all necessary parameters are stored in the EEPROM 53 so as to be selectable in the present invention.

  In this subroutine, the brake plate is driven only by the resonance frequency detected in the subroutine “resonance point detection operation” described above.

  FIG. 14 shows the relationship between the frequency and the amplitude of the vibration brake. The characteristic when executing the subroutine “resonance point detection operation” is * 3. The resonance frequency fc corresponds to f4 in FIG. However, there is a possibility that the characteristic fluctuates as * 4 and * 5 due to an unexpected factor of the resonance frequency. In order to cope with such a change, the subroutine 53 may be executed by reading the data of f3 and f5 other than f4 from the table of the EEPROM 53.

  Also, since the resonance frequency fluctuates within a certain range depending on the temperature, the most suitable resonance frequency at the operating temperature can be maintained by appropriately setting and holding the temperature correction table created by a predetermined experiment. Then, the brake plate may be driven. For this purpose, temperature information (t) is detected by a temperature sensor of a temperature measurement circuit (not shown) before executing this subroutine in order to read out a parameter corresponding to the temperature at that time from the temperature correction table corresponding to the vibration mode. Just keep it.

1 is a perspective view schematically showing an internal configuration of a part of an electronic camera according to an embodiment of the present invention. It is a block block diagram which shows schematically the electric structure mainly of this electronic camera. It explains the action of the vibration brake, and is a perspective view showing the structure of the main part of the quick return mirror 15a and its drive mechanism. It explains the action of the vibration brake, and is a diagram for explaining the stopped state of the finder observation position and the exposure retract position of the quick return mirror 15a. The operation of the vibration brake will be described. (A) is a cross-sectional view showing a specific configuration of the vibration brake, (b) is a diagram illustrating an example of bending vibration of the brake plate, and (c) is a bending of the brake plate It is a figure explaining the other example of a vibration. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram illustrating a configuration of a vibration brake drive circuit, explaining a drive of a vibration brake and its operation and control in an embodiment of the present invention. It is a timing chart explaining the drive of a vibration brake and its operation | movement and control in one Embodiment of this invention. FIG. 3 is a diagram showing electrodes of a piezoelectric element for detecting a vibration state of a brake plate 100 to which a friction sheet 103, a piezoelectric element 101, and a flexible substrate 106a are fixed. 5 is a flowchart for explaining the operation of a camera sequence under the control of a body control microcomputer (Bμcom) 31. FIG. 9 is a flowchart illustrating a resonance frequency detection operation in two types of vibration modes in the subroutine “resonance point detection operation” in step S3 in the flowchart of FIG. It is a map. The control parameters relating to the frequency correction of the vibration mode are shown. (A) is a list showing details of the control parameter table corresponding to vibration mode 1, and (b) is a list showing details of the control parameter table corresponding to vibration mode 2. . The correction value corresponding to a vibration mode is shown, (a) is a detailed table of a frequency correction table corresponding to vibration mode 1, and (b) is a detailed table of a frequency correction table corresponding to vibration mode 2. 10 is a flowchart illustrating details of a subroutine “resonance point detection operation” in step S2 in the flowchart of FIG. 9. It is the characteristic view which showed the relationship between the frequency and the amplitude of a brake plate. 10 is a flowchart for explaining a subroutine “vibration brake operation” in step S16 in the flowchart of FIG. 9.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electronic camera, 11 ... Camera body part, 12 ... Lens barrel, 12a ... Shooting optical system, 15 ... Finder apparatus, 15a ... Quick return mirror, 16 ... Shutter part, 16a ... Shutter, 20 ... Lens unit, 21 ... Lens control microcomputer (Lμcom), 22 ... Photography lens, 23 ... Aperture, 24 ... Lens drive mechanism, 25 ... Aperture drive mechanism, 30 ... Body unit, 31 ... Microcomputer for body control (B [mu] com), 31a ... Clock generator 33 ... AF sensor unit, 34 ... AF sensor drive circuit, 35 ... mirror drive mechanism, 36 ... shutter charge mechanism, 37 ... shutter control circuit, 38 ... photometry circuit, 40a, 40b ... vibration brake, 41a, 41b, 101 ... Piezoelectric element, 42 ... vibration brake drive circuit, 44 ... CCD unit (Imaging device), 46 ... CCD interface circuit, 47 ... liquid crystal monitor, 51 ... image processing controller, 53 ... nonvolatile memory (EEPROM), 55 ... camera operation switch (SW), 61 ... mirror, 62 ... mirror holding Frame, 64 ... Mirror shaft, 65 ... Fixed frame, 69 ... Mirror drive roller, 70 ... Drive lever shaft, 71 ... Mirror drive lever, 72, 90 ... Cam, 75 ... Drive lever spring, 81 ... Drive lever roller, 82 ... Cam lever 95 ... Stopper A, 96 ... Stopper B, 100 ... Brake plate, 102 ... Brake pin, 103 ... Friction sheet, 104 ... Anti-vibration sheet, 121 ... N-adic counter, 122 ... 1/2 frequency divider, 123 ... Inverter 124 ... Transformer, 125 ... A / D converter.

Claims (9)

In the mirror drive system of a single-lens reflex camera,
A movable mirror supported so as to be movable between a finder observation position and an exposure retract position;
A mirror drive mechanism for moving the movable mirror to the viewfinder observation position or exposure retract position;
A friction stop mechanism for stopping the movable mirror at the finder observation position or the exposure retracted position by a frictional force;
A release mechanism for releasing the frictional force of the friction stop mechanism;
A mirror drive system comprising:   2. The mirror drive system according to claim 1, wherein the release mechanism releases the frictional force by applying vibration to a frictional force generation unit of the friction stop mechanism. The friction stop mechanism is
A friction portion provided on the movable mirror;
A friction spring attached to a fixed frame holding the movable mirror movably, having elasticity and having a friction sliding surface;
Consisting of
2. The movable mirror is stopped at a predetermined position by the friction spring pressing the friction sliding surface of the spring against the friction portion of the movable mirror near the stop position of the movable mirror. Mirror drive system.   The mirror driving system according to claim 1, wherein the friction stop mechanism includes a vibrator having a piezoelectric element fixed to an elastic body.   2. The mirror drive system according to claim 1, wherein the friction stop mechanism generates a vibration for operating the movable mirror toward the viewfinder observation position or the exposure retreat position when the vibration is applied.   The mirror driving system according to claim 4, wherein the piezoelectric element is provided with an electrode for driving and an electrode for detecting vibration of the piezoelectric element.   The mirror driving system according to claim 4, wherein a plurality of vibration modes are sequentially generated in the vibrator.   2. The mirror drive system according to claim 1, wherein the friction stop mechanism and the release mechanism are provided at least with respect to the exposure retracted position.   2. The mirror drive system according to claim 1, wherein the friction stop mechanism and the release mechanism are provided for at least one of the finder observation position and the exposure retract position.

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