JP2007047502A - Optical system driving unit and driving method for piezoelectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical system driving unit in which open control that eliminates the need for a position detecting sensor is achieved, the effect of the hysteresis of piezoelectric elements is reduced, and following responsiveness is high. <P>SOLUTION: The optical system driving unit includes the piezoelectric elements 34a and 34b that are distorted by application of a voltage, and drives a reflecting member 22 by the piezoelectric elements 34a and 34b. The optical system driving device is characterized by including a voltage application section 19 by which the piezoelectric elements 34a and 34b are subjected to the application of a high frequency voltage by making the high frequency voltage being higher than the mechanical resonance frequency of the optical mechanism system composed of the piezoelectric elements 34a and 34b and reflecting member 22 and lower than the natural frequencies of the piezoelectric elements 34a and 34b overlap with a DC voltage applied to drive the reflecting member 22 to a predetermined position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical system driving device, for example, to a piezoelectric actuator type optical system driving device using a piezoelectric element as a driving source of an optical system in a camera such as a digital camera or a camera-equipped mobile phone. is there.

  Since the piezoelectric element expands and contracts when a voltage is applied and is reversible, attempts have been made to use it in an optical system driving device that requires fine positioning accuracy.

  However, it is generally known that piezoelectric elements have hysteresis characteristics. FIG. 5 is a graph showing an example of hysteresis characteristics of the piezoelectric element. The horizontal axis of the graph of FIG. 5 indicates the voltage V applied to the piezoelectric element, and the vertical axis indicates the displacement amount X of the piezoelectric element.

  As shown in FIG. 5, for example, when the voltage applied to the unpolarized piezoelectric element is increased so that the voltage value changes from the initial state O of V = 0 to V = V1, the piezoelectric element becomes a broken line in the figure. It changes from origin O to point B along S. Subsequently, when the applied voltage of the piezoelectric element is lowered to V = 0, the piezoelectric element changes from point B to point A along the upper curve Q in the figure as shown in FIG. At this time, although the applied voltage is set to V = 0, the residual displacement amount Xa remains in the piezoelectric element.

  Furthermore, when the applied voltage of the piezoelectric element is increased again from V = 0 to V = V1 from this state, the piezoelectric element changes from point A to point B along the lower curve P in the figure. Thereafter, when the applied voltage V is lowered to V = 0 from the state of the point C on the lower curve P in the drawing, the piezoelectric element changes from the point C to the point A along the curve R. Further, when the voltage V2 is applied to the piezoelectric element, for example, when the applied voltage V is increased from the voltage 0 to V2 corresponding to the state of the point A, the displacement amount of the piezoelectric element changes from Xa to X1. . Further, when the applied voltage V is lowered from the point C to V2, the displacement amount of the piezoelectric element becomes X2, and when the applied voltage V is lowered from the point B to V2, the displacement amount of the piezoelectric element is X3. It becomes.

  As described above, the hysteresis characteristic of the piezoelectric element is such that the relationship between the displacement amount X of the piezoelectric element and the applied voltage V applied to the piezoelectric element does not correspond one-to-one, and the previous state (the state immediately before the voltage is applied). ) Differs in the displacement amount X of the piezoelectric element, which prevents precise control using the piezoelectric element.

  A method of accurately displacing the piezoelectric element while avoiding the influence of the hysteresis characteristics of the piezoelectric element is disclosed in Patent Document 1. Patent Document 1 relates to a bending optical system driving device for a camera with a camera shake correction function using a feedback control method. Specifically, the current position of the control object is detected by attaching a position detection sensor to the control object to be positioned. Next, an error between the current position of the control object and the target position is detected. Then, the piezoelectric element is driven to the target position based on the detected error. Thereby, a piezoelectric element can be displaced accurately.

Patent Document 2 discloses an example of an optical system driving method for accurately stopping the focus lens drive using a piezoelectric element. Specifically, when a certain voltage is applied to the piezoelectric element, the applied voltage of the piezoelectric element is always increased along the hysteresis curve, and then the applied voltage is returned to the initial value. Next, the applied voltage is raised from the returned initial value to the target voltage again. Thereby, the displacement amount of the piezoelectric element can be determined by the lower curve of the hysteresis loop.
JP 2004-219930 A (released on August 5, 2004) Japanese Unexamined Patent Application Publication No. 2004-205742 (released on July 22, 2004)

  However, the above-described conventional configuration has the following problems.

  Specifically, in the feedback-type optical system driving device using the position detection sensor disclosed in Patent Document 1, a space for arranging the position detection sensor is required. As a result, there arises a problem of increasing the size of the optical system driving device. Further, since a dedicated feedback control circuit is required, a problem of cost increase arises.

  Further, in the optical system driving method disclosed in Patent Document 2, every time the displacement amount of the piezoelectric element is changed, the displacement amount corresponding to one round of the hysteresis loop is finished, and then the target position is determined. Therefore, there arises a problem that it cannot be used for a servo system that requires follow-up responsiveness such that the target position dynamically changes with time.

  The present invention has been made in view of the above problems, and its object is to perform an open control that does not require a position detection sensor, reduce the influence of hysteresis of the piezoelectric element, and drive an optical system with high tracking response. To provide an apparatus.

  An optical system driving apparatus according to the present invention is an optical system driving apparatus that includes a piezoelectric element that generates distortion upon application of a voltage, and drives the optical element by the piezoelectric element, and includes the piezoelectric element and the optical element. A high frequency voltage that is higher than the mechanical resonance frequency of the optical mechanism system and lower than the natural frequency of the piezoelectric element is superimposed on a DC voltage applied to drive the optical element to a predetermined position. And a voltage applying means for applying the voltage to the piezoelectric element.

  The piezoelectric element driving method according to the present invention has a frequency higher than a mechanical resonance frequency of an optical mechanism system including the piezoelectric element and the optical element and lower than a natural frequency of the piezoelectric element. Voltage applying means for applying the high frequency voltage to the piezoelectric element by superimposing the high frequency voltage on a DC voltage applied to drive the optical element to a predetermined position is provided.

  The optical element indicates an optical system component including at least one of a lens, a mirror, a prism, and the like, for example. In other words, the optical element causes at least one phenomenon of light refraction, reflection, separation, polarization, and light collection.

  The mechanical resonance frequency of the optical mechanism system indicates the natural frequency of the optical mechanism system when the optical mechanism system is composed of one member, and the optical mechanism system includes a plurality of members. In the case where it is configured, for example, it is a frequency calculated by a computer simulation using a finite element method or the like.

  According to the above configuration, the DC voltage applied to drive the optical element to a predetermined position is set to a frequency within a range higher than the mechanical resonance frequency of the optical mechanism system and lower than the natural frequency of the piezoelectric element. A voltage obtained by superimposing the alternating current voltage is applied to the piezoelectric element.

  When the frequency of the superposed high frequency voltage is equal to or lower than the mechanical resonance frequency of the optical mechanism system, the piezoelectric element follows the high frequency voltage superposed on the direct current voltage to generate a displacement. Become. Accordingly, the optical element cannot be linearly driven with respect to a DC voltage applied to drive the piezoelectric element to a predetermined position. As a result, the optical element cannot be moved (driven) to a desired position.

  Further, when the frequency of the superposed high frequency voltage is equal to or higher than the natural frequency of the piezoelectric element, no displacement occurs in the piezoelectric element.

  Therefore, by superimposing a high frequency voltage (AC voltage) having a frequency within a range higher than the mechanical resonance frequency of the optical mechanism system and lower than the natural frequency of the piezoelectric element on the DC voltage, the piezoelectric element Since the influence of the hysteresis characteristic can be reduced, the optical element can be driven linearly.

  The optical system driving apparatus according to the present invention may be configured such that the frequency of the high-frequency voltage is equal to or higher than the audible frequency.

  The piezoelectric element driving method according to the present invention may be configured such that the frequency of the high-frequency voltage is equal to or higher than an audible frequency.

  According to said structure, the frequency of the high frequency voltage applied to a piezoelectric element is set more than the audible frequency. Accordingly, when the frequency is higher than the audible frequency, it cannot be heard by a person, so that no audible noise is generated when the optical element is driven.

  In the optical system driving device according to the present invention, when the DC voltage is applied to the piezoelectric element in order to fix the position of the optical element, the voltage application is performed so as not to superimpose the high-frequency voltage. The structure provided with the control means which controls a means may be sufficient.

  In the piezoelectric element driving method according to the present invention, when the DC voltage is applied to the piezoelectric element in order to fix the position of the optical element, the high frequency voltage is not superimposed. The structure provided with the control means which controls the said voltage application means may be sufficient.

  When the optical element is driven, the high-frequency voltage is applied for the purpose of linearly driving the optical element. When the position of the optical element is fixed, it is not necessary to apply the high-frequency voltage.

  According to said structure, in order to fix the position of the said optical element, when applying DC voltage with respect to a piezoelectric element, it controls so that the said high frequency voltage is not applied. In other words, with the above configuration, the high frequency voltage is applied only when the optical element is driven. Thereby, since an unnecessary high frequency voltage is not applied, the power consumption of the optical system driving device can be reduced.

  Therefore, in order to drive the optical element, the optical system driving device according to the present invention performs the superimposed application of the high-frequency voltage in cases other than applying a DC voltage to the piezoelectric element. It may be configured to include a control means for controlling the voltage application means so as not to exist.

An optical system driving apparatus according to the present invention is an optical system driving apparatus that includes a piezoelectric element that generates distortion by applying a voltage, and drives the optical element by the piezoelectric element,
A high-frequency voltage that is higher than the mechanical resonance frequency of the optical mechanism system including the piezoelectric element and the optical element and lower than the natural frequency of the piezoelectric element is driven to the predetermined position. For this purpose, voltage applying means for applying the voltage to the piezoelectric element is superimposed on the DC voltage to be applied.

  Therefore, since the hysteresis characteristic of the piezoelectric element can be reduced, the optical element can be driven linearly. As a result, it is possible to provide an optical system driving device with high follow-up response by reducing the influence of hysteresis of the piezoelectric element by open control that does not require a position detection sensor.

  The piezoelectric element driving method according to the present invention has a frequency higher than a mechanical resonance frequency of an optical mechanism system including the piezoelectric element and the optical element and lower than a natural frequency of the piezoelectric element. In this configuration, a high-frequency voltage is superimposed on a DC voltage applied to drive the optical element to a predetermined position, and applied to the piezoelectric element.

  Therefore, according to the driving method of the piezoelectric element configured as described above, the same operation as that of the optical system driving device of the present invention is realized, so that the same effect as that of the optical system driving device of the present invention can be obtained. .

  One embodiment of the present invention will be described below with reference to FIGS. In this embodiment, an example in which the present invention is applied to a camera body having a camera shake correction function including a bending optical system as an optical system driving device will be described. In addition, an optical system such as a digital still camera or a digital video camcorder is used. The optical system driving device can also be applied to the focusing device.

  The camera body in this embodiment includes a camera unit optical system, and the camera unit optical system includes an optical system driving device having a camera shake correction function. The optical system driving device is a device for driving an optical mechanism system, that is, an optical element such as a mirror.

  FIG. 3 is a perspective view showing a schematic configuration of the camera unit optical system according to the present embodiment. First, the camera unit optical system 100 provided in the camera body will be described below with reference to FIG.

  The camera unit optical system 100 includes a front lens 21, a reflecting member 22 (optical element, optical mechanism system), an imaging lens group 23, an imaging element 24, and a shake correction device 30 (optical mechanism system, optical system driving device). Yes.

  The front lens 21 is a lens into which the light beam of the subject image is incident, and guides the incident light beam of the subject image to the reflecting member 22.

  The reflecting member 22 reflects the light beam of the subject image incident from the front lens 21 and guides it to the imaging lens group 23. Examples of the reflection member 22 include a prism and a reflection mirror. The reflecting member 22 in the present embodiment has a triangular prism shape with a right-angled isosceles triangle, and reflects light incident on a 45-degree slope at the same angle as the incident angle.

  The imaging lens group 23 is a group of lenses that guides the light beam reflected by the reflecting member 22 to the imaging element 24.

  The image sensor 24 captures a subject image by performing photoelectric conversion. That is, the image sensor 24 acquires image data. Examples of the image pickup device 24 include a CCD (charge coupled device).

  The blur correction device 30 is an optical path correction member that changes the optical path that enters the image sensor 24. The details of the shake correction apparatus 30 will be described later.

  Here, a configuration in which the light beam of the subject image incident on the camera unit optical system 100 enters the image sensor 24 will be described below. Here, a case where the light beam of the subject image incident on the camera unit optical system 100 is incident from a direction parallel to the imaging surface of the image sensor 24 will be described.

  As shown in FIG. 3, the light beam of the subject image incident on the camera unit optical system 100 from the direction of the optical axis A (the direction parallel to the imaging surface of the image sensor 24) in the drawing passes through the front lens 21. The reflection member 22 made of a prism or the like is reached. Next, the light beam reflected at a right angle by the reflecting member 22 passes through the imaging lens group 23 arranged along the optical axis B (a direction orthogonal to the imaging surface of the imaging element 24), and passes through the imaging element 24. To reach. Then, the light is condensed by the image sensor 24 and an image is formed, and image data is generated.

  Even when the light beam of the subject image incident on the camera unit optical system 100 is incident from a direction that is not parallel to the imaging surface of the image sensor 24, the blur correction device 30 attached to the back surface of the reflecting member 22 is used. The optical path from the front lens 21 to the image sensor 24 is adjusted, and a subject image with reduced blur is incident on the image sensor 24.

  This shake correction device 30 corrects the optical axis shake between the yawing direction which is the rotation direction around the optical axis B shown in the figure and the pitching direction which is the rotation direction around the axis orthogonal to the optical axis A and the optical axis B. Is provided to do. The yawing direction and the pitching direction are directions orthogonal to each other.

  FIG. 4 is an exploded perspective view showing the overall configuration of the shake correction apparatus 30. Here, the configuration of the shake correction apparatus 30 will be described in detail with reference to FIG.

  The shake correction device 30 includes a reflection member base 31, a shake correction device base 33, piezoelectric elements 34 a and 34 b (optical mechanism system), and a piezoelectric element fixing member 36.

  The reflection member base 31 is bonded and fixed to the back surface of the reflection member 22, that is, the surface opposite to the surface that reflects the light beam. The reflecting member base 31 is fixed to a camera body casing (not shown) in a movable state. The reflection member base 31 is provided with a central protrusion 32, pressing protrusions 35a and 35b, and preload protrusions 37a and 37b.

  The central protrusion 32 is provided at a substantially central portion of the reflecting member base 31 so as to protrude in a vertical direction from a surface opposite to the surface on which the reflecting member base 31 is fixed to the reflecting member 22. Further, the central projection so that a straight line passing through the center of the central projection 32 and parallel to the central projection 32 intersects with a straight line passing through the center of the optical axis A shown in FIG. 32 is provided.

  The pressing portion protrusions 35 a and 35 b are provided so as to protrude from the surface opposite to the surface on which the reflecting member base 31 is fixed to the reflecting member 22. Further, the straight lines connecting the respective pressing portion protrusions 35a and 35b and the central portion protrusion 32 form a right-angled isosceles triangle, and the central portion protrusion 32 is disposed at the right-angle portion.

  Here, the positions of the pressing portion protrusions 35a and 35b will be described in detail below.

  First, the reflecting member 22 is in a state where a plane having a straight line parallel to the optical axis A and a straight line parallel to the optical axis B and the reflecting surface of the reflecting member 22 are orthogonal to each other, in other words, the light beam is directed to the camera body. Assume that the light is incident at a right angle and is reflected at a right angle by the reflecting member. At this time, the pressing portion protrusion 35b is provided on the reflecting member base 31 surface on which the pressing portion protrusion 35b is provided so that the center point of the pressing portion protrusion 35b is located on the rotation surface in the pitching direction with respect to the optical axis A. It has been. Further, as described above, the pressing portion protrusion 35a is positioned so that the pressing portion protrusion 35a and the pressing portion protrusion 35b are positioned at the apex angle in the right isosceles triangle having the center of the center portion protrusion 32 as the vertex of the right angle portion. It is provided on the reflecting member base 31 surface.

  The preload protrusions 37a and 37b are provided so as to protrude in a vertical direction from a surface opposite to the surface on which the reflecting member base 31 is fixed to the reflecting member 22. The preload portion protrusion 37a is provided on the reflecting member base 31 so that the central portion protrusion 32 is positioned on a straight line passing through the preload portion protrusion 37a and the pressing portion protrusion 35a. And the preload part protrusion 37b is provided in the reflection member base 31 so that the center part protrusion 32 may be located on the straight line which passes along the said preload part protrusion 37b and the press part protrusion 35b.

  The shake correction device base 33 is for fixing the shake correction device 30 to the camera barrel 1. The blur correction device base 33 is provided with a leaf spring-shaped elastic member 38 that contacts the preload portion protrusion 37. In addition, an opening for penetrating piezoelectric elements 34a and 34b described later is provided near the center of the shake correction device base 33, and a piezoelectric element fixing member 36 is screwed around the opening. A female screw hole is provided. Furthermore, a through hole for inserting the center protrusion 32 provided on the reflection member base 31 is provided at the center of the shake correction device base 33. The through hole has a size that can accommodate the center protrusion 32 in a loosely fitted state.

  The piezoelectric elements 34a and 34b are passive elements utilizing the effect of converting a force applied to the piezoelectric body into a voltage or converting a voltage applied to the piezoelectric body into a force. The piezoelectric elements 34a and 34b of the present embodiment have a laminated structure, and are formed by sticking a large number of piezoelectric elements into a rod shape. When a voltage is applied, the piezoelectric elements 34a and 34b are reflected in the longitudinal direction of the piezoelectric elements, that is, the reflection It is displaced in a direction perpendicular to the reflection surface of the member 22. Details of the piezoelectric elements 34a and 34b will be described later.

  The piezoelectric element fixing member 36 fixes one end of the piezoelectric elements 34a and 34b, and is fixed to the shake correction apparatus base 33 via a screw.

  The shake correction device 30 includes the above-described configurations, that is, the reflection member base 31, the shake correction device base 33, the piezoelectric elements 34a and 34b, and the piezoelectric element fixing member 36 in order from the reflection member 22 side.

  Next, the configuration of the shake correction apparatus 30 will be described in more detail with reference to FIGS. 3 and 4.

  First, the reflection member base 31 is bonded and fixed to the back surface of the reflection member 22 as described above. A center protrusion 32 provided on the reflection member base 31 is inserted in an open state in an opening provided in the center of the shake correction device base 33. In addition, the preload portion protrusion 37 provided on the reflection member base 31 and the elastic member 38 provided on the shake correction device base 33 are in contact with each other, and the urging force acts between the reflection member base 31 and the shake correction device base 33. It is held in the state.

  In addition, one end of each of the piezoelectric elements 34 a and 34 b passes through the shake correction device base 33 and contacts the pressing portion protrusions 35 a and 35 b provided on the reflecting member base 31, and the other end is bonded and fixed to the piezoelectric element fixing member 36. Has been. As a result, a pressure is applied between the piezoelectric elements 34a and 34b and the pressing portion protrusions 35a and 35b.

  Thereby, the reflection member base 31 and the shake correction apparatus base 33 are held in a state in which an urging force is always acting between them.

  Here, when a voltage is applied to the piezoelectric element 34a, the piezoelectric element 34a extends in the longitudinal direction (a direction orthogonal to the reflecting surface of the reflecting member 22). When the piezoelectric element 34a extends in the longitudinal direction, the pressing portion protrusion 35a that is in contact with the piezoelectric element 34a is pushed. The reflecting member base 31 receives the pressure from the pressing portion protrusion 35a and moves together with the reflecting member 22 in the yawing direction shown in FIG. At this time, the preload portion protrusion 37a provided on the reflecting member base 31 is biased from the portion that contacts the preload portion protrusion 37a of the elastic member 38 provided on the shake correction device base 33 according to the displacement of the piezoelectric element 34a. Move in the direction against the biasing force while receiving.

  Further, when a voltage is applied to the piezoelectric element 34b, the piezoelectric element 34b extends in the longitudinal direction (direction orthogonal to the reflecting surface of the reflecting member 22). When the piezoelectric element 34b extends in the longitudinal direction, the pressing portion protrusion 35b in contact with the piezoelectric element 34b is pushed. Then, the reflecting member base 31 receives the pressure from the pressing portion protrusion 35b, and moves together with the reflecting member 22 in the pitching direction shown in FIG. At this time, the preloading portion protrusion 37b provided on the reflecting member base 31 is biased from the portion that contacts the preloading portion protrusion 37b of the elastic member 38 provided on the shake correction device base 33 according to the displacement of the piezoelectric element 34b. Move in the direction against the biasing force while receiving.

  By the way, when the voltage applied to the piezoelectric elements 34a and 34b is lowered, the piezoelectric elements 34a and 34b contract in the longitudinal direction. When the piezoelectric elements 34a and 34b are contracted in the longitudinal direction, the reflecting member base 31 receives a biasing force from the elastic member 38 via the preloading portion protrusions 37a and 37b, thereby moving the moving direction when a voltage is applied. Will move in the opposite direction.

  In addition, in a state where no voltage is applied to the piezoelectric elements 34a and 34b, the reflecting member base 31 is returned to the initial position.

  In this way, the reflecting member base 31 can be moved by applying a voltage to the piezoelectric elements 34a and 34b or lowering the applied voltage.

  Here, since the reflecting member base 31 is bonded and fixed to the back surface of the reflecting member 22, the reflecting member base 31 and the reflecting member 22 are configured to be movable as a unit. The reflecting member base 31 is fixed to the housing of the camera body so as to be movable. Further, the reflecting member base 31 is not fixed to the camera barrel 1 that is a housing for fixing the imaging lens group 23, the imaging device 24, the shake correction device base 33, and the like.

  With the above configuration, the reflecting member base 31 and the reflecting member 22 can be moved relative to the camera barrel 1. Specifically, the angle of the reflecting surface of the reflecting member 22 can be changed with respect to the image sensor 24.

  Here, for example, when camera shake occurs due to a user operation while the user is shooting with the camera, the optical path guided to the light receiving surface of the image sensor 24 changes. As a result, an unclear blurred image is captured by the image sensor 24.

  Therefore, when camera shake occurs, the reflecting member 22 can be moved by utilizing the displacement of the piezoelectric elements 34a and 34b obtained by applying a voltage to the piezoelectric elements 34a and 34b. Then, by moving the reflecting surface of the reflecting member 22, the optical path incident on the camera unit optical system 100 can be changed and accurately guided to the image sensor 24. As a result, image blur caused by camera shake can be corrected.

  Incidentally, since the piezoelectric elements 34a and 34b have hysteresis characteristics as described above, it is difficult to accurately control the amount of displacement. As a result, the reflecting member 22 cannot be moved to a desired position. Therefore, a configuration for reducing the hysteresis characteristics of the piezoelectric elements 34a and 34b and moving the reflecting member 22 to a desired position will be described below.

  FIG. 1 is a block diagram showing a schematic configuration of a control system for controlling the operation of each component included in the shake correction apparatus 30. First, the configuration of the control system of the shake correction apparatus 30 will be described with reference to FIG.

  The control system of the shake correction device 30 includes a yawing direction angular velocity sensor 10, a pitching direction angular velocity sensor 11, a shake angular velocity detection circuit 12, an A / D conversion unit 13, an MPU 14 (control means), a voltage application unit 19, a shake correction device 30, A reflection member 22 is provided.

  The yawing direction angular velocity sensor 10 and the pitching direction angular velocity sensor 11 are detectors that detect the angular velocity of blurring that occurs in the camera barrel 1, and are provided in the camera barrel 1. Specifically, for example, the yawing direction angular velocity sensor 10 and the pitching direction angular velocity sensor 11 detect the angular velocity of blurring when the camera barrel 1 moves due to camera shake, and output an angular velocity signal. The yawing direction angular velocity sensor 10 is a sensor that detects blur in the yaw direction of the camera barrel 1, and the pitching direction angular velocity sensor 11 is a sensor that detects blur in the pitch direction of the camera barrel 1.

  The blur angular velocity detection circuit 12 performs signal noise removal processing, filtering processing for cutting drift, and amplification processing, and outputs each processed signal to the A / D conversion unit 13.

  The A / D converter 13 is a converter that converts an analog voltage signal into a digital signal. Then, the A / D conversion unit 13 outputs the converted digital signal to the MPU 14.

  The MPU 14 is an arithmetic unit that calculates the blur angle of the camera barrel 1 by integrating digital signals. Further, the MPU 14 determines respective target displacement amounts corresponding to the shake angles of the yawing direction driving piezoelectric element 34 a and the pitching direction driving piezoelectric element 34 b in the shake correction apparatus 30. Further, the MPU 14 gives a command as to whether or not to supply the high frequency voltage generated by the high frequency drive voltage generation circuit 16 to the DC voltage generated by the DC drive voltage generation circuits 15a and 15b to the switch 17 described later.

  The voltage application unit 19 applies a voltage to each of a later-described piezoelectric element 34a for driving in the yawing direction and a piezoelectric element 34b for driving in the pitching direction based on a command from the MPU 14. The voltage application unit 19 includes DC drive voltage generation circuits 15a and 15b, a high frequency drive voltage generation circuit 16, a switch 17, and adders 18a and 18b.

  The DC drive voltage generation circuits 15a and 15b are circuits that generate DC voltages to be applied to the yawing direction driving piezoelectric element 34a and the pitching direction driving piezoelectric element 34b, respectively.

  The high frequency drive voltage generation circuit 16 is a circuit that generates a high frequency voltage.

  The switch 17 switches whether to supply the high-frequency voltage generated by the high-frequency drive voltage generation circuit 16 to the DC voltage generated by the DC drive voltage generation circuits 15a and 15b based on a command from the MPU 14.

  Based on a command from the MPU 14, the switch 17 is turned on, that is, the timing for supplying a high frequency is controlled to be immediately before the camera shake correction operation is started, that is, immediately before the start of exposure. Further, the timing at which the switch 17 is turned off based on a command from the MPU 14, that is, the high frequency is cut off, is controlled to be after the camera shake correction operation, that is, after the exposure.

  The on / off timing of the switch 17 is not limited to the above, and may be based on an instruction from the user, for example.

  The adders 18a and 18b add the high-frequency voltage output from the high-frequency drive voltage generation circuit 16 to the DC voltage output from the DC drive voltage generation circuits 15a and 15b. Then, the added voltages are applied to the yawing direction driving piezoelectric element 34a and the pitching direction driving piezoelectric element 34b, respectively.

  The reflection member 22 moves based on the displacement of the piezoelectric elements 34a and 34b provided in the shake correction device 30. And the optical path of the light ray which injects into the reflection member 22 is changed.

  The blur correction process is performed by the control system configured as described above.

  Next, the blur correction processing operation in the control system of the blur correction apparatus 30 will be described with reference to FIG. In the following, a description will be given of a case where blur correction is simultaneously performed in two directions, a yawing direction and a pitching direction.

  First, exposure starts when the user presses the shutter of the camera. If the camera barrel 1 is moved by camera shake immediately before the exposure starts, the yawing direction angular velocity sensor 10 and the pitching direction angular velocity sensor 11 are the angular velocities of the camera barrel 1 in the yawing direction and pitching direction. Are detected, and an angular velocity signal indicating the detection result is output. At this time, the switch 17 is turned on based on a command from the MPU 14.

  Next, the blur angular velocity detection circuit 12 receives the angular velocity signals output from the yawing direction angular velocity sensor 10 and the pitching direction angular velocity sensor 11. The blur angular velocity detection circuit 12 generates an analog voltage signal by performing noise removal processing, filtering processing for cutting drift, and amplifier processing on the angular velocity signal. Next, the blur angular velocity detection circuit 12 outputs the analog voltage signal to the A / D converter 13. The blur angular velocity detection circuit 12 generates analog voltage signals in the yawing direction and the pitching direction, respectively.

  The A / D converter 13 converts the analog voltage signal acquired from the shake angular velocity detection circuit 12 into a digital signal (digital angular velocity signal). Then, the A / D conversion unit 13 outputs the converted digital angular velocity signal to the MPU 14. The analog voltage signal is input from the shake angular velocity detection circuit 12 to the A / D converter 13 at a constant cycle.

  The MPU 14 performs an integration process on the digital angular velocity signal transmitted from the A / D conversion unit 13 and calculates respective blur angles in the yaw direction and the pitching direction of the camera barrel unit 1. At the same time, the MPU 14 determines the target displacement amounts of the yawing direction driving piezoelectric element 34a and the pitching direction driving piezoelectric element 34b in the shake correcting apparatus 30 based on the calculated shake angle. Then, the MPU 14 outputs the determined target displacement amount to the DC drive voltage generation circuits 15a and 15b, respectively.

  Next, the DC drive voltage generation circuits 15a and 15b generate the front ball shown in FIG. 3 based on the respective target displacement amounts of the yawing direction driving piezoelectric element 34a and the pitching direction driving piezoelectric element 34b calculated by the MPU 14. The yawing direction driving piezoelectric element 34a and the pitching direction driving piezoelectric element 34b are based on the displacement angle characteristics determined from the lens power of the lens 21, the prism rotation center shown in FIG. 4, and the pressing positions of the piezoelectric elements 34a and 34b. The DC voltage applied to each is output.

  A high frequency voltage is output from the high frequency drive voltage generation circuit 16. The high-frequency voltage has a frequency within a range that is higher than the mechanical resonance frequency of the optical mechanism system, that is, the reflection member 22 and the shake correction device 30, and lower than the natural frequency of the piezoelectric elements 34a and 34b. Voltage (AC voltage). The high-frequency voltage is a sine wave-like AC voltage with a small amplitude that draws a hysteresis loop, and the amplitude and frequency are constant.

  Next, the adders 18a and 18b add the high-frequency voltage output from the high-frequency drive voltage generation circuit 16 to the direct-current voltages output from the DC drive voltage generation circuits 15a and 15b. The adders 18a and 18b apply respective voltages obtained by adding the DC voltage and the high-frequency voltage to the yawing direction driving piezoelectric element 34a and the pitching direction driving piezoelectric element 34b, respectively.

  The yawing direction driving piezoelectric element 34a and the pitching direction driving piezoelectric element 34b are displaced according to the voltages applied by the adders 18a and 18b, respectively.

  Accordingly, the reflecting member 22 moves in the yawing direction and the pitching direction based on the displacement of the yawing direction driving piezoelectric element 34a and the pitching direction driving piezoelectric element 34b.

  As described above, when the camera shake occurs, the shake correction apparatus 30 of the present embodiment reflects the direct current voltage output from the direct current drive voltage generation circuits 15a and 15b from the high frequency drive voltage generation circuit 16. A high frequency voltage (AC voltage) having a frequency that is higher than the mechanical resonance frequency between the member 22 and the shake correction device 30 and lower than the natural frequency of the piezoelectric elements 34a and 34b is superimposed. Then, by applying the superimposed voltage to the piezoelectric elements 34a and 34b, the reflecting member 22 is moved using the displacement of the piezoelectric elements 34a and 34b.

  And according to said structure, when camera shake generate | occur | produces, the reflection member 22 is moved by utilizing the displacement of piezoelectric element 34a * 34b obtained by applying a voltage to piezoelectric element 34a * 34b. Can do. Then, by moving the reflecting surface of the reflecting member 22, the optical path incident on the camera unit optical system 100 can be changed and accurately guided to the image sensor 24. As a result, image blur caused by camera shake can be corrected.

  The method for determining the target displacement amount by the MPU 14 is not limited to the method for calculating the target displacement amount every time as described above, and may be determined by the following method, for example.

  The MPU 14 has in advance a table (not shown) in which the intensity of the digital angular velocity signal and the target displacement amount are associated with each other. When the digital angular velocity signal is acquired from the A / D conversion unit 13, the MPU 14 determines a target displacement amount using the table. That is, since the blur angle and the target displacement amount have a certain relationship, a table in which the target displacement amount is calculated in advance and the target displacement amount and the intensity of the digital angular velocity signal are associated with each other is calculated. It may be used. Thus, the MPU 14 may determine the target displacement amount with reference to the table.

  Further, the method for determining the DC voltage applied to each of the piezoelectric element 34a for driving in the yawing direction and the piezoelectric element 34b for driving in the pitching direction is not limited to the method for calculating the DC voltage every time as described above, but includes, for example, the following method You may decide by.

  The DC drive voltage generation circuits 15a and 15b have a table (not shown) in which the target displacement amount and the DC voltage are associated with each other in advance. When the target displacement amount is acquired from the MPU 14, the DC drive voltage generation circuits 15a and 15b determine the DC voltage using the table. That is, since the target displacement amount and the DC voltage have a certain relationship, the DC voltage is calculated in advance, and a table in which the target displacement amount and the DC voltage are associated with each other may be used. . Thus, the DC drive voltage generation circuits 15a and 15b may determine the DC voltage with reference to the table.

  FIG. 2A shows a yawing direction driving piezoelectric element 34a and a pitching direction driving piezoelectric element 34b when a high frequency voltage (AC voltage) is superimposed on a DC driving voltage (DC voltage) for driving the piezoelectric elements 34a and 34b. It is a graph which shows the voltage displacement characteristic.

  The AC voltage superimposed on the DC voltage is a high-frequency voltage that is higher than the mechanical resonance frequency of the reflecting member 22 and the shake correction device 30 and lower than the natural frequency of the piezoelectric elements 34a and 34b. Also, it is a sinusoidal voltage with a small amplitude that draws a hysteresis loop. Therefore, as shown in FIG. 2A, the piezoelectric elements 34a and 34b are displaced while drawing a minute hysteresis loop with respect to the change of the DC voltage.

  Thus, the hysteresis characteristic of the piezoelectric elements 34a and 34b can be reduced by applying a voltage obtained by superimposing the high-frequency voltage on the DC voltage to the piezoelectric elements 34a and 34b.

  FIG. 2B is a graph showing the voltage displacement (angle) characteristics of the reflecting member 22 when a voltage obtained by superimposing the high-frequency voltage on the DC voltage is applied to the piezoelectric elements 34a and 34b.

  As described above, since the frequency of the superimposed high-frequency voltage is set higher than the mechanical resonance frequency, the reflecting member 22 does not follow a component higher than the mechanical resonance frequency. As a result, the hysteresis characteristics of the piezoelectric elements 34a and 34b can be reduced, and the reflecting member 22 can be driven linearly without depending on the change direction of the DC voltage, as shown in FIG. 2B. it can.

  Therefore, according to the above configuration, it is possible to provide an optical system driving device with high follow-up response by reducing the influence of hysteresis of the piezoelectric elements 34a and 34b by open control that does not require a position detection sensor.

  As described above, according to the configuration of the present embodiment, the DC voltage applied to drive the reflecting member 22 to a predetermined position is greater than the mechanical resonance frequency between the shake correction device 30 and the reflecting member 22, and A voltage obtained by superimposing a voltage in a frequency range lower than the natural frequency of the piezoelectric elements 34a and 34b is applied to the piezoelectric elements 34a and 34b. The mechanical resonance frequency between the shake correction device 30 and the reflection member 22 is a frequency calculated by a computer simulation using a finite element method or the like, for example.

  Here, when the frequency of the high frequency voltage to be superimposed on the piezoelectric elements 34a and 34b is equal to or lower than the mechanical resonance frequency between the blur correction device 30 and the reflection member 22, the high frequency voltage superimposed on the DC voltage is used. Then, the piezoelectric elements 34a and 34b follow to generate displacement. Therefore, the reflecting member 22 cannot be driven linearly with respect to a DC voltage applied to drive the piezoelectric elements 34a and 34b to predetermined positions. As a result, the reflecting member 22 cannot be moved (driven) to a desired position.

  Further, when the frequency of the superposed high frequency voltage is equal to or higher than the natural frequency of the piezoelectric elements 34a and 34b, no displacement occurs in the piezoelectric elements 34a and 34b. Since the hysteresis characteristic cannot be reduced unless the piezoelectric elements 34a and 34b are displaced, the reflecting member 22 cannot be driven linearly.

  Therefore, by superimposing a voltage within a frequency range that is higher than the mechanical resonance frequency of the shake correction device 30 and the reflection member 22 and lower than the natural frequency of the piezoelectric elements 34a and 34b on the DC voltage. Since the hysteresis characteristics of the piezoelectric elements 34a and 34b can be reduced, the reflecting member 22 can be driven linearly.

  Further, by setting the frequency of the high-frequency drive voltage generation circuit 16 to be higher than the audible frequency, it is possible to reduce unpleasant noise when driving the optical element.

  Further, when the reflecting member 22 is stopped or in a standby state, the switch 17 is turned off to cut off the supply of the high frequency voltage from the high frequency drive voltage generation circuit 16, and the piezoelectric elements 34a and 34b are displaced only by the DC voltage. Retained.

  Further, the high frequency voltage is applied for the purpose of linearly driving the reflecting member 22 when the reflecting member 22 is driven. When the position of the reflecting member 22 is fixed, it is not necessary to apply the high frequency voltage. .

  According to said structure, in order to fix the position of the reflection member 22, when applying DC voltage with respect to piezoelectric element 34a, 34b, it controls so that the said high frequency voltage is not applied. In other words, with the above configuration, the high-frequency voltage is applied only when the reflecting member 22 is driven. Thereby, since an unnecessary high frequency voltage is not applied, the power consumption of the optical system driving device can be reduced.

  The reason why the hysteresis characteristics of the piezoelectric elements 34a and 34b are minimized (small) as shown in FIG. 2A is obtained by simply miniaturizing the high-frequency amplitude of the superimposed high-frequency AC voltage. Instead, it is determined by optimizing the combination of the frequency and amplitude of the high-frequency AC voltage superimposed in the actual system.

  In addition, the influence of the hysteresis characteristic can be reduced by superimposing the high frequency voltage. However, when the frequency of the superposed high frequency voltage is lower than the mechanical resonance frequency, the reflecting member 22 follows the high frequency voltage component to cause the displacement. Therefore, the linearity with respect to the change of the DC voltage is lost, and the movement becomes jerky and cannot be used for camera shake correction.

  Therefore, in order to realize a driving circuit (driving method) for the piezoelectric elements 34a and 34b that can reduce the influence of the hysteresis characteristic and perform a smooth optical system operation with good linearity, it is superimposed on the DC voltage. It is optimal to set the frequency of the high-frequency voltage to be in a range that is higher than the mechanical resonance frequency of the blur correction device 30 and the reflection member 22 and lower than the natural frequency of the piezoelectric elements 34a and 34b.

  Furthermore, the frequency of the high-frequency voltage is preferably 20 KHz or higher, which is a frequency higher than the audible range, in order to reduce noise during driving. The frequency of the high-frequency voltage is not limited to this. Check the hysteresis reduction effect while increasing the frequency step by step, check the hysteresis reduction effect due to amplitude change, and the hysteresis reduction effect is driven by the optical system. It is preferable to select the combination that minimizes the power consumption among the combinations of the frequency and amplitude of the high-frequency voltage that satisfies the required specifications of the apparatus.

  Therefore, the frequency range of the high-frequency voltage may be from about 20 KHz beyond the audible range to the upper limit frequency that allows the piezoelectric elements 34a and 34b to generate displacement, that is, the natural frequency of the piezoelectric elements 34a and 34b. preferable.

  In addition, in the case of a configuration in which the frequency of the high-frequency voltage is varied and superimposed on the DC voltage, a fluctuation (sweep) circuit needs to be added, resulting in an increase in cost. Therefore, it is preferable to always set the frequency of the superimposed high-frequency voltage to a constant numerical value.

  The optical system driving apparatus according to the present embodiment is a mechanical resonance frequency of an optical mechanism system including the optical system element in the optical system driving apparatus that drives the optical system element using a distortion generated in the piezoelectric element by voltage application as a driving force source. A configuration including voltage applying means for applying a DC voltage on which the above high-frequency voltage is superimposed to the piezoelectric element may be employed.

The optical system driving device may be configured such that a frequency of the high-frequency voltage is equal to or higher than an audible frequency. Further, the optical system driving device is configured so that the optical system element is stopped when the optical system element is stopped. A switching unit that does not superimpose the high-frequency voltage may be provided. The driving method of the piezoelectric element may be a configuration in which the high-frequency voltage is superimposed on the DC driving voltage applied to the piezoelectric element.

  Further, the piezoelectric element driving method may be configured such that the frequency of the high-frequency voltage is equal to or higher than a mechanical resonance frequency of a driving mechanism using a strain generated in the piezoelectric element as a driving force source.

  The piezoelectric element driving method may be configured such that the frequency of the high-frequency voltage is equal to or higher than an audible frequency.

  Further, the piezoelectric element driving method may be provided with a switching unit that does not superimpose the high-frequency voltage when the driving mechanism is stopped.

  An experiment was performed to determine the optimum condition of the voltage applied to the piezoelectric elements 34a and 34b provided in the shake correction apparatus 30 of the above embodiment. This will be described below.

  First, an experiment was performed to measure the displacement angle of the reflecting member 22 when a DC voltage was applied to the piezoelectric elements 34a and 34b. In the above experiment, a PMC350-0.2A manufactured by kikusui was used as the DC power source, and an autocollimator (LA2400 manufactured by Keyence) was used as a device for measuring the tilt amount. The results are shown in Table 1.

  Table 1 shows the results of measuring the displacement angle (tilt amount) of the reflecting member 22 in the pitching direction when a DC voltage is applied to the piezoelectric element 34b. FIG. 6A is a graph showing the results of Table 1.

  Next, the displacement angle (tilt amount) of the reflecting member 22 in the yawing direction when a DC voltage was applied to the piezoelectric element 34a was measured. The results are shown in Table 2. FIG. 6B is a graph showing the results of Table 2.

  From the results shown in Tables 1 and 2 and FIGS. 6A and 6B, when a DC voltage of 40 V is applied to the piezoelectric elements 34a and 34b, the tilt amount of the reflecting member 22 is 10 'or more in the pitching direction and yawing direction, respectively. It was found that it can be displaced. It can also be seen that the displacement angle varies depending on the voltage application direction to the piezoelectric element, that is, the step-up direction and the step-down direction. This phenomenon is due to the hysteresis characteristic of the piezoelectric element. A method for reducing the hysteresis characteristics of the piezoelectric elements 34a and 34b will be described later.

  Next, an experiment for examining frequency characteristics (frequency response characteristics) was performed using an FFT servo analyzer (R9211C manufactured by Advantest Corporation).

  FIG. 10A is a graph showing the relationship between frequency, gain, and phase in the frequency range from 1 Hz to 100 Hz, and FIG. 10B is the frequency in the frequency range from 100 Hz to 500 Hz. It is the graph which showed the relationship between a gain and a phase.

  From FIG. 10 (a), it can be seen that there is no change in gain and phase in the range of 20 Hz or less, which is the camera shake frequency range, and it is flat. 10B, there is a peak at 180 Hz, which is the temporary resonance frequency (mechanical resonance frequency) of this mechanism even in the range of 500 Hz or less, but this is not a problem because it is sufficiently higher than the frequency range of camera shake.

  Next, the following experiment was conducted on the method of driving the piezoelectric elements 34a and 34b.

  First, hysteresis was measured when an AC voltage was superimposed on a DC drive voltage.

  In order to reduce the hysteresis of the piezoelectric elements 34a and 34b, the drive voltage applied to the piezoelectric elements 34a and 34b is larger than the mechanical resonance frequency between the reflecting member 22 and the shake correcting device 30 and is inherent to the piezoelectric elements 34a and 34b. Evaluation was performed by varying the drive voltage in a state where a frequency within a range lower than the frequency, specifically, a high-frequency AC voltage of 10 KHz to 40 KHz was superimposed. The mechanical resonance frequency was 180 Hz as a result of calculation by computer simulation using a finite element method or the like. The natural frequency of the piezoelectric element is 100 kHz.

  Therefore, the driving conditions are such that the superposed frequency is 10 KHz, 20 KHz, 30 KHz, and 40 KHz, and the superposed voltage and waveform are sine waveforms of p-p4V, p-p8V, and p-p12. In addition, the frequency of the high frequency voltage to be superimposed on the DC voltage applied to the piezoelectric elements 34a and 34b in the present embodiment is within the above frequency, that is, in the range of 10 KHz to 40 KHz.

  From the results shown in FIGS. 13A to 13D, the method of superimposing the high-frequency AC voltage on the piezoelectric elements 34a and 34b is effective in reducing the hysteresis, and the pixel based on the hysteresis characteristics by superimposing the high-frequency AC voltage. It is possible to reduce the influence of the shift to 0.5 pixels or less.

  Next, an experiment was conducted to measure the displacement angle of the reflecting member 22 when the high-frequency AC voltage was superimposed on the AC drive voltage.

  Even when superposition of the high-frequency AC voltage is performed, it can be confirmed that the reflecting member 22 follows the command signal up to 20 Hz in a similar manner without being affected by the superposition waveform of the high-frequency AC voltage. Further, FIG. 8A to FIG. 9B when the superposition of the high-frequency AC voltage described later is not performed and FIGS. 14A to 15B when the high-frequency AC voltage is superimposed. Comparing the Lissajous waveforms, it can be seen that the influence of the hysteresis characteristics of the piezoelectric elements 34a and 34b is reduced.

  In this experiment, in order to compare the influence of the hysteresis characteristics of the reflecting member 22, the high-frequency AC voltage is superimposed on the AC driving voltage, but the frequency of the AC driving voltage does not affect the comparison. The frequency is set lower than the frequency of the high-frequency AC voltage. That is, the AC voltage means a camera shake frequency lower than the mechanical resonance frequency. More specifically, the AC drive is performed assuming that the DC voltage that determines the displacement of the piezoelectric elements 34a and 34b fluctuates at the camera shake frequency. Dynamic characteristics are measured using voltage. Therefore, even if the experiment is performed using the drive voltage applied to the piezoelectric elements 34a and 34b as an AC drive voltage, the same effect as when a DC drive voltage (DC voltage) is applied can be obtained.

  Next, the blur suppression characteristic was evaluated using the evaluation system shown in FIG. As an evaluation method, first, the shake correction device 30 having a prism attached on an automatic rotation stage is fixed. Next, the rotation stage is swung without driving the blur correction device 30, and the PSD output amplitude is measured. The measurement result is shown in FIG.

  Next, the swinging state of the rotary stage is measured by a displacement sensor, the blur correction device 30 is driven using the signal, and the PSD output amplitude at that time is measured. The measurement result is shown in FIG. Then, the measured PSD output amplitudes are compared.

12 (a) and 12 (b), it is understood that the shake amount of the prism can be suppressed to ¼ or less by synchronizing the shake correction device 30 with the movement of the rotary stage.
[Comparative example]
Here, an experiment was conducted to measure the displacement angle of the reflecting member 22 when the high-frequency AC voltage is not superimposed on the AC drive voltage applied to the piezoelectric elements 34a and 34b.

  Note that the displacement angle characteristic of the shake correction device 30 when a high-frequency AC voltage is superimposed is measured by configuring the evaluation system shown in FIG. 7 because the frequency band of the autocollimator is low and cannot be measured by the same method as described above. . In this evaluation system, as shown in FIG. 7, a prism is attached to the shake correction apparatus 30 to reflect incident light from a light source (parallel light). And it is the structure which can calculate the displacement angle amount of a prism by receiving this reflected light with PSD (Position Sensitive Detector).

  As can be seen from FIGS. 8A to 9B, noise unnecessary for the PSD output (CH1) representing the prism tilt with respect to the drive voltage (CH2) applied to the piezoelectric element in the frequency range of 0.5 Hz to 20 Hz. It can be seen that it has a similar shape without any signs. Thereby, it can be seen that the shake correction apparatus 30 operates well in the range up to 20 Hz which is the camera shake correction range.

  In addition, as shown in the Lissajous waveform (C1 / C2) in FIGS. 8A to 9B, a phenomenon in which the locus is different between when the drive voltage is increased and when the voltage is decreased can be confirmed. This seems to be due to the hysteresis characteristics of the piezoelectric elements 34a and 34b.

  Thus, it can be seen that the effect of hysteresis cannot be reduced when the high-frequency AC voltage is not superimposed on the AC drive voltage applied to the piezoelectric elements 34a and 34b.

  The present invention can be applied to all optical system driving devices using a piezoelectric element as a driving source, and in particular, it can be applied to an optical system driving device of a portable photographing apparatus by downsizing. Also, it is only necessary to obtain a minute displacement by the piezoelectric element, and even with open control, there is no influence of the hysteresis of the piezoelectric element, the position detecting element is unnecessary, and the circuit configuration can be easily made. (Tunneling microscope), semiconductor manufacturing apparatus, XY precision stage, and micropositioning apparatus such as a magnetic recording apparatus tracking mechanism.

1, showing an embodiment of the present invention, is a block diagram showing a schematic configuration of a shake correction apparatus. FIG. (A) is a graph which shows the voltage displacement characteristic of the piezoelectric element provided in a blurring correction apparatus, (b) is a graph which shows the voltage displacement characteristic of a reflection member. It is a perspective view which shows schematic structure of the camera unit optical system provided with the said blurring correction apparatus. It is a disassembled perspective view which shows the whole structure of the said blurring correction apparatus. It is a graph which shows the hysteresis characteristic of a piezoelectric element. (A) is the graph which showed the relationship between the direct current voltage applied to a piezoelectric element, and the displacement angle of the pitching direction of a piezoelectric element, (b) is the direct current voltage applied to a piezoelectric element, and the yawing direction of a piezoelectric element. It is the graph which showed the relationship with a displacement angle. It is the top view which showed the evaluation system for measuring the displacement angle of a reflection member at the time of applying an alternating current drive voltage to a piezoelectric element. (A) is the wave form diagram which showed the relationship between the displacement angle of a reflection member at the time of setting the frequency of the alternating current drive voltage applied to a piezoelectric element to 0.5 Hz, and alternating current drive voltage, (b) is a piezoelectric element. It is the wave form diagram which showed the relationship between the displacement angle of a reflection member at the time of setting the frequency of the alternating current drive voltage applied to 1Hz to alternating current drive voltage, and (c) is the frequency of the alternating current drive voltage applied to a piezoelectric element. It is the wave form diagram which showed the relationship between the displacement angle of a reflection member at the time of setting to 5 Hz, and alternating current drive voltage. (A) is the wave form diagram which showed the relationship between the displacement angle of a reflection member at the time of setting the frequency of the alternating current drive voltage applied to a piezoelectric element to 10 Hz, and alternating current drive voltage, (b) is applied to a piezoelectric element. It is the wave form diagram which showed the relationship between the displacement angle of a reflection member at the time of setting the frequency of the alternating current drive voltage to 20 Hz, and alternating current drive voltage. (A) is a graph showing the relationship between frequency, gain and phase in the frequency range from 1 Hz to 100 Hz, and (b) is the frequency, gain and phase in the frequency range from 100 Hz to 500 Hz. It is the graph which showed the relationship. It is the top view which showed the evaluation system for measuring the characteristic of camera shake correction. (A) is a waveform diagram showing the shake amount of the reflection member when the shake correction device is off, and (b) is a waveform diagram showing the shake amount of the reflection member when the shake correction device is on. is there. (A) is the graph which showed the relationship between the direct-current voltage and hysteresis characteristic at the time of superimposing the alternating voltage of a frequency of 10 Hz on the direct-current voltage applied to a piezoelectric element, (b) is applied to a piezoelectric element. It is the graph which showed the relation between the direct-current voltage at the time of superposing the alternating voltage of the frequency of 20 Hz on the direct-current voltage, and the characteristic of hysteresis, and (c) is the direct-current voltage impressed to the piezoelectric element. It is the graph which showed the relationship between the direct current voltage at the time of superimposition, and the characteristic of hysteresis, (d) is the characteristic of direct current voltage and hysteresis at the time of superimposing the alternating voltage of a frequency of 40 Hz on the direct current voltage applied to a piezoelectric element. It is the graph which showed the relationship. (A) is a waveform diagram showing the relationship between the displacement angle of the reflecting member and the AC voltage when a high-frequency AC voltage is superimposed on an AC drive voltage with a frequency of 0.5 Hz applied to the piezoelectric element, (b) FIG. 6 is a waveform diagram showing the relationship between the displacement angle of the reflecting member and the AC voltage when a high-frequency AC voltage is superimposed on the AC drive voltage of 1 Hz frequency applied to the piezoelectric element, and FIG. It is the wave form diagram which showed the relationship between the displacement angle of a reflection member at the time of superimposing a high frequency alternating voltage on the alternating current drive voltage of the frequency of 5 Hz to apply, and alternating voltage. (A) is a waveform diagram showing the relationship between the displacement angle of the reflecting member and the AC voltage when a high-frequency AC voltage is superimposed on an AC drive voltage with a frequency of 10 Hz applied to the piezoelectric element, and (b) It is the wave form diagram which showed the relationship between the displacement angle of a reflection member at the time of superimposing a high frequency alternating voltage on the alternating current drive voltage of the frequency of 20 Hz applied to a piezoelectric element, and an alternating voltage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera barrel part 10 Yawing direction angular velocity sensor 11 Pitching direction angular velocity sensor 14 MPU (control means)
15a and 15b DC drive voltage generation circuit 16 High frequency drive voltage generation circuit 17 Switch 18a and 18b Adder 19 Voltage application unit (voltage application means)
22 Reflective member (optical element, optical mechanism system)
30 Shake correction device (optical mechanism system)
34a, 34b Piezoelectric element (optical mechanism system)
100 Camera unit optical system

Claims (6)

An optical system driving device including a piezoelectric element that generates distortion by applying a voltage, and driving an optical element by the piezoelectric element,
A high-frequency voltage that is higher than the mechanical resonance frequency of the optical mechanism system including the piezoelectric element and the optical element and lower than the natural frequency of the piezoelectric element is driven to the predetermined position. An optical system driving device comprising voltage applying means for applying to the piezoelectric element while being superimposed on a DC voltage to be applied.   2. The optical system driving apparatus according to claim 1, wherein the frequency of the high-frequency voltage is not less than an audible frequency.   When the DC voltage is applied to the piezoelectric element in order to fix the position of the optical element, control means for controlling the voltage applying means so as not to superimpose the high frequency voltage is provided. The optical system driving apparatus according to claim 1 or 2,   A high-frequency voltage that is higher than the mechanical resonance frequency of the optical mechanism system including the piezoelectric element and the optical element and lower than the natural frequency of the piezoelectric element is driven to the predetermined position. A drive method for a piezoelectric element, comprising voltage applying means for applying to the piezoelectric element in a manner superimposed on a DC voltage applied for the purpose.   The method for driving a piezoelectric element according to claim 4, wherein the frequency of the high-frequency voltage is equal to or higher than an audible frequency.   When the DC voltage is applied to the piezoelectric element in order to fix the position of the optical element, control means for controlling the voltage applying means so as not to superimpose the high frequency voltage is provided. 6. The method for driving a piezoelectric element according to claim 4, wherein the piezoelectric element is driven.

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