JP2011170196A - Piezoelectric actuator and optical scanning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric actuator, relaxing non-linear deformation due to hysteresis characteristics of a piezoelectric body. <P>SOLUTION: The piezoelectric actuator 50 includes: a piezoelectric body 42 formed to extend linearly in the Y direction and deforming non-linearly based on the hysteresis characteristic; a lower electrode 41 on one surface of the piezoelectric body 42; an upper electrode 51 on the other surface of the piezoelectric body 42; and an applied voltage control part 1 for applying voltage to the lower electrode 41 and the upper electrode 51. The upper electrode 51 is divided into split electrodes 51a-51g linearly extending from the end side on the Y1 side of the piezoelectric body 42 to the end side on the Y2 side thereof. The applied voltage control part 1 can apply voltage to the split electrodes 51a-51g individually, and the number of the split electrodes 51a-51g to which voltage is applied is gradually increased or decreased to thereby deform the piezoelectric body 42 or return the deformation of the piezoelectric body 42. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a piezoelectric actuator and an optical scanning device, and more particularly to a piezoelectric actuator and an optical scanning device in which electrodes are divided.

  Conventionally, a piezoelectric actuator and an optical scanning device in which electrodes are divided are known (for example, see Patent Document 1).

  Patent Document 1 discloses an optical switch (optical scanning device) including a mirror element and a pair of piezoelectric elements formed on both sides of the mirror element in the first direction and extending in the first direction. Each of the pair of piezoelectric elements includes a lower electrode and a piezoelectric body formed so as to extend in the first direction, and an upper surface of the piezoelectric body and divided into one side and the other side in the first direction. And two upper electrodes. Further, the optical switch of Patent Document 1 is configured such that alternating voltages having opposite phases are always applied to the two upper electrodes provided in each piezoelectric element. Here, it is known that the piezoelectric body has a characteristic (hysteresis characteristic) in which the displacement amount with respect to the applied voltage increases nonlinearly and the displacement amount with respect to the released voltage decreases nonlinearly.

WO2003 / 062899

  However, since the optical switch described in Patent Document 1 is configured such that an AC voltage is always applied to the two upper electrodes provided in each piezoelectric element, it corresponds to the lower part of the upper electrode. Each piezoelectric body is considered to repeat non-linear deformation based on hysteresis characteristics. For this reason, there is a problem in that non-linear deformation due to the hysteresis characteristics of the piezoelectric body is not relaxed.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to provide a piezoelectric actuator capable of mitigating non-linear deformation caused by the hysteresis characteristics of a piezoelectric body, and An optical scanning device is provided.

Means for Solving the Problems and Effects of the Invention

  A piezoelectric actuator according to a first aspect of the present invention is formed so as to extend linearly along a first direction and deforms nonlinearly based on hysteresis characteristics when a voltage is applied, and the piezoelectric body A first electrode formed on one surface of the piezoelectric body so as to extend linearly from one end side in the first direction of the piezoelectric body to the other end side; and a first electrode of the piezoelectric body on the other surface of the piezoelectric body. A second electrode formed so as to extend linearly from one end side to the other end side of the direction, and a voltage applying means for applying a voltage to the first electrode and the second electrode. At least one of the two electrodes is divided into a plurality of divided electrodes extending linearly from one end side to the other end side in the first direction of the piezoelectric body, and the voltage applying means is provided for the plurality of divided electrodes. Individual voltage can be applied and voltage can be Number by sequentially increasing or decreasing the divided electrodes to be pressurized, and is configured to return the deformation of or piezoelectric deforming the piezoelectric element.

  In the piezoelectric actuator according to the first aspect of the present invention, as described above, at least one of the first electrode and the second electrode is divided into a plurality of divided electrodes, and the number of divided electrodes to which a voltage is applied by the voltage applying means. Unlike the case where the piezoelectric body is deformed by the total displacement amount by applying a single voltage, the small displacement amount obtained by dividing the total displacement amount of the piezoelectric body is configured by deforming the piezoelectric body by sequentially increasing. The piezoelectric body can be gradually deformed minute by minute to reach the deformation for the entire displacement amount. Similarly, at least one of the first electrode and the second electrode is divided into a plurality of divided electrodes, and the number of the divided electrodes to which the voltage is applied is sequentially decreased by the voltage applying means so that the deformation of the piezoelectric body is restored. Unlike the case where the piezoelectric body to which the voltage is applied is returned to the deformation of the entire displacement amount by releasing the voltage once, the piezoelectric body is gradually increased by the small displacement amount obtained by dividing the total displacement amount of the piezoelectric body. The deformation of the piezoelectric body can be returned and the deformation corresponding to the total displacement amount can be returned. As a result, it is possible to disperse the non-linear deformation caused by the hysteresis characteristic of the piezoelectric body (characteristic that the displacement amount with respect to the applied voltage increases nonlinearly and the displacement amount with respect to the released voltage decreases nonlinearly). Therefore, non-linear deformation due to the hysteresis characteristics of the piezoelectric body can be mitigated.

  In the piezoelectric actuator according to the first aspect, preferably, the voltage application unit individually switches between a state in which a substantially constant voltage is applied to a plurality of divided electrodes and a state in which no voltage is applied. Thus, the number of divided electrodes to which a voltage is applied is configured to increase or decrease sequentially. If configured in this manner, the magnitude of the voltage is substantially constant and it is not necessary to control the magnitude of the voltage as compared with the case where the magnitude of the voltage by the voltage application means is controlled in consideration of the hysteresis characteristics. Non-linear deformation caused by the hysteresis characteristic of the piezoelectric body can be dispersed and relaxed more easily without performing complicated control.

  In the piezoelectric actuator according to the first aspect described above, preferably, the voltage applying means includes a split electrode that applies the voltage so that the total area of the split electrodes to which the voltage is applied increases or decreases sequentially with a substantially constant size. The number is configured to increase or decrease sequentially. With this configuration, unlike the case where the total area of the divided electrodes to which the voltage is applied is sequentially increased or decreased at different sizes, the number of divided electrodes to which the voltage is applied is always substantially increased or decreased. Since the piezoelectric body can be deformed so as to increase or decrease by the same amount of deformation, the deformation of the piezoelectric body can be made close to linear. Thereby, the piezoelectric actuator can be driven more stably.

  In the piezoelectric actuator according to the first aspect, preferably, the plurality of divided electrodes pass through the center of the piezoelectric body in the second direction substantially orthogonal to the first direction and are substantially symmetrical with respect to the center line extending in the first direction. It is arranged to be. If comprised in this way, it can suppress that a piezoelectric actuator inclines along a 2nd direction, without performing complicated control by a voltage application means, Therefore A piezoelectric actuator can be driven more stably. .

  In this case, preferably, the plurality of divided electrodes are respectively disposed on the first divided electrode through which the center line of the piezoelectric body passes through the center in the second direction and on both sides of the first divided electrode in the second direction. And a pair of second divided electrodes having an approximately half area. If comprised in this way, by making the electrode area of a 1st division | segmentation electrode and the sum total of the electrode area of a pair of 2nd division | segmentation electrode into a substantially equal amount, the displacement amount with respect to the applied voltage has a proportional relationship and linearly The piezoelectric body can be deformed in a state close to an increasing state and a state close to a state in which the amount of displacement with respect to the released voltage has a proportional relationship and decreases linearly.

  In the piezoelectric actuator in which the plurality of divided electrodes include a first divided electrode and a pair of second divided electrodes, preferably, the plurality of divided electrodes are the first divided electrodes in the second direction of the pair of second divided electrodes. A pair of third divided electrodes each disposed on the opposite side and having an approximately half area of the first divided electrode, and a first divided electrode in the second direction of the pair of third divided electrodes, respectively, disposed on the opposite side, And a pair of fourth divided electrodes having a substantially half area of the first divided electrode. According to this structure, the electrode area of the first divided electrode, the total electrode area of the pair of second divided electrodes, the total electrode area of the pair of third divided electrodes, and the electrode of the pair of fourth divided electrodes By making the total area substantially equal, the displacement amount with respect to the applied voltage has a proportional relationship and the state in which the displacement amount is linearly increased and the displacement amount with respect to the released voltage has a proportional relationship and has a linear relationship. The piezoelectric body can be deformed in a state close to the decreasing state. Further, by increasing the number of divided electrodes, the piezoelectric body can be deformed in a state where the influence of the hysteresis characteristic of the piezoelectric body is further dispersed.

  In the piezoelectric actuator according to the first aspect, preferably, the voltage applying means applies a voltage from the divided electrode on the center line side of the piezoelectric body toward the divided electrodes on both ends in the second direction substantially orthogonal to the first direction. By sequentially applying and maintaining the applied state, the number of divided electrodes to which a voltage is applied is sequentially increased, so that the piezoelectric body is deformed and the center of the piezoelectric body is separated from the divided electrodes on both ends in the second direction. By sequentially releasing the voltage held toward the line-side divided electrode, the number of divided electrodes to which the voltage is applied is sequentially reduced, so that the deformation of the piezoelectric body is restored. If comprised in this way, unlike the case where the state which applied and applied the voltage to arbitrary division electrodes among a plurality of division electrodes is held, from the division electrode on the center line side toward the division electrode on the both end portions side Since the piezoelectric body can be sequentially deformed, the piezoelectric body can be easily deformed uniformly. Similarly, unlike the case of releasing the voltage of an arbitrary divided electrode among a plurality of divided electrodes, the deformation of the piezoelectric body can be released sequentially from the divided electrodes on both ends toward the divided electrode on the center line side. Therefore, the deformation of the piezoelectric body can be easily released. As a result, the piezoelectric actuator can be driven more stably.

  An optical scanning device according to a second aspect of the present invention is formed so as to extend linearly along a first direction, and a piezoelectric body that deforms nonlinearly based on hysteresis characteristics when a voltage is applied thereto, and a piezoelectric A first electrode formed on one surface of the body so as to extend linearly from one end side in the first direction of the piezoelectric body to the other end side; and a first electrode of the piezoelectric body on the other surface of the piezoelectric body. A piezoelectric actuator including a second electrode formed to extend linearly from one end side to the other end side in one direction; and a voltage applying means for applying a voltage to the first electrode and the second electrode; A plurality of divisions extending from one end side to the other end side in the first direction of the piezoelectric body, at least one of the first electrode and the second electrode. Divided into electrodes, The voltage applying means can individually apply a voltage to the plurality of divided electrodes, and can sequentially deform or deform the piezoelectric body by increasing or decreasing the number of divided electrodes to which the voltage is applied. It is comprised so that a deformation | transformation may be returned.

  In the optical scanning device according to the second aspect of the present invention, as described above, at least one of the first electrode and the second electrode of the piezoelectric actuator is divided into a plurality of divided electrodes, and a voltage is applied by the voltage applying means. Unlike the case where the piezoelectric body is deformed by the amount of total displacement by applying a single voltage, the total displacement amount of the piezoelectric body is divided by configuring the piezoelectric body to be deformed by sequentially increasing the number of divided electrodes. The piezoelectric body can be gradually deformed by the small displacement amount to reach the deformation for the entire displacement amount. Similarly, at least one of the first electrode and the second electrode is divided into a plurality of divided electrodes, and the number of the divided electrodes to which the voltage is applied is sequentially decreased by the voltage applying means so that the deformation of the piezoelectric body is restored. Unlike the case where the piezoelectric body to which the voltage is applied is returned to the deformation of the entire displacement amount by releasing the voltage once, the piezoelectric body is gradually increased by the small displacement amount obtained by dividing the total displacement amount of the piezoelectric body. The deformation of the piezoelectric body can be returned and the deformation corresponding to the total displacement amount can be returned. As a result, it is possible to disperse the non-linear deformation caused by the hysteresis characteristic of the piezoelectric body (characteristic that the displacement amount with respect to the applied voltage increases nonlinearly and the displacement amount with respect to the released voltage decreases nonlinearly). Therefore, non-linear deformation due to the hysteresis characteristics of the piezoelectric body can be mitigated. Thereby, a mirror part can be rotated stably.

1 is a perspective view illustrating a structure of an optical scanning device according to an embodiment of the present invention. It is the top view which showed the structure of the optical scanning device by one Embodiment of this invention. 1 is a block diagram illustrating a configuration of an optical scanning device according to an embodiment of the present invention. It is an enlarged plan view showing an upper electrode of a piezoelectric actuator of a Y direction optical scanning unit of an optical scanning device according to an embodiment of the present invention. It is an expanded sectional view along line 1000-1000 of the optical scanning device shown in FIG. FIG. 3 is an enlarged cross-sectional view of the optical scanning device shown in FIG. 2 taken along line 2000-2000. It is the graph which showed the displacement amount of the piezoelectric actuator in one Embodiment and comparative example of this invention. It is the perspective view which showed the state which the optical scanning device by one Embodiment of this invention inclined with the predetermined | prescribed angle (inclination angle (theta) 1). It is the side view which showed the state which the optical scanning device by one Embodiment of this invention inclined with the predetermined | prescribed angle (inclination angle (theta) 1).

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.

  First, the configuration of an optical scanning device 100 according to an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, an optical scanning device 100 according to an embodiment of the present invention scans light in the X direction using an applied voltage control unit 1 (see FIG. 1) and a mirror 11 described later. X-direction optical scanning unit 10 and a Y-direction optical scanning unit 30 for scanning light in the Y-direction orthogonal to the X-direction using a mirror 11. Further, the X direction light scanning unit 10 and the Y direction light scanning unit 30 are integrally formed on a common Si substrate 3 (see FIG. 5). The applied voltage control unit 1 is an example of the “voltage application unit” in the present invention, and the X-direction optical scanning unit 10 is an example of the “mirror unit” in the present invention.

  As shown in FIG. 3, the applied voltage control unit 1 includes upper electrodes 43 of inner driving units 16 and 17 (to be described later) of the X direction optical scanning unit 10 and driving units 31 and 33 (to be described later) of the Y direction optical scanning unit 30. It is electrically connected to the upper electrode 51. The applied voltage control unit 1 applies a voltage to the upper electrodes 43 of the inner driving units 16 and 17 and the upper electrodes 51 of the driving units 31 and 33 of the Y-direction optical scanning unit 30, so that the X-direction optical scanning unit 10 and The Y direction optical scanning unit 30 is configured to be driven. The specific voltage control of the applied voltage control unit 1 will be described later.

  As shown in FIG. 2, the optical scanning device 100 is incorporated in a device that scans light such as a projector (not shown), and scans light in the X direction around the rotation center R <b> 1 by the X direction optical scanning unit 10. The Y-direction light scanning unit 30 scans light in the Y direction around the rotation center R2. The X-direction optical scanning unit 10 is configured to be resonantly driven by the applied voltage control unit 1 (see FIG. 1) at a resonance frequency of about 30 kHz, while the Y-direction optical scanning unit 30 is. Is configured to be controlled so as to be non-resonantly driven at a frequency of about 60 Hz. Here, by configuring the Y-direction optical scanning unit 30 to be non-resonantly driven, there is no change in the resonance frequency due to the temperature change around the optical scanning device 100, so that the mirror 11 described later can be stably It is possible to drive.

  As shown in FIGS. 1 and 2, the X-direction optical scanning unit 10 is connected to the mirror 11, the torsion bars 12 and 13 that are connected to the mirror 11, and torsionally deformable, and torsion bars 12. , A tiltable bar 15 connected to the torsion bar 13, inner drive parts 16 and 17 connected to the bars 14 and 15, and fixing parts 18 and 19 for fixing the inner drive parts 16 and 17. The frame 20 is included.

  Further, as shown in FIG. 1, the mirror 11 and the torsion bars 12 and 13 are configured to be inclined more than the inclination angle of the bars 14 and 15 by resonance. Further, the inner drive units 16 and 17 are configured to be deformed into a concave shape or a convex shape in the Z direction with the fixed portions 18 and 19 as fixed ends, respectively. The inner drive unit 16 and the inner drive unit 17 are deformed in directions opposite to each other so that the mirror 11 can be tilted in the A1 direction or the A2 direction around the rotation center R1 (see FIG. 2). Has been. Further, by repeating this deformation operation, the X-direction optical scanning unit 10 is configured to cause the mirror 11 to vibrate in the A direction around the rotation center R1 and to scan light in the X direction.

  Further, as shown in FIG. 6, the inner drive units 16 and 17 are configured to be driven by a piezoelectric actuator 40 formed on the upper surface (the surface on the Z1 side) of the Si substrate 3. The piezoelectric actuator 40 has a structure in which a lower electrode 41, a piezoelectric body 42, and an upper electrode 43 are laminated from the Si substrate 3 side (Z2 side).

  The lower electrode 41 is made of Ti or Pt and is formed on the upper surface of the Si substrate 3. Thus, the wiring process to the lower electrode 41 can be performed on any part of the Si substrate 3. In the present embodiment, the lower electrode 41 is grounded via the wiring 2 from the upper surface of the frame body 20 as shown in FIG.

  The piezoelectric body 42 is made of lead zirconate titanate (PZT) and is configured to expand and contract when a voltage is applied by being polarized in the film thickness direction (Z direction). As shown in FIG. 7, the piezoelectric body 42 has a so-called hysteresis characteristic in which the displacement amount with respect to the applied voltage increases nonlinearly and the displacement amount with respect to the released voltage decreases nonlinearly. The piezoelectric body 42 is also formed on the upper surface of the lower electrode 41 of the mirror support portions 32 and 34 (see FIG. 2).

  The upper electrode 43 is made of a conductive metal material such as Al, Cr, Cu, Au, or Pt. As shown in FIGS. 1 and 2, the upper electrode 43 is not divided into a plurality of parts, unlike an upper electrode 51 described later of the drive units 31 and 33. Further, the upper electrodes 43 of the inner driving units 16 and 17 are configured to be applied with voltages having opposite phases to each other by the applied voltage control unit 1 (see FIG. 1).

  In addition, as shown in FIG. 2, the Y-direction optical scanning unit 30 includes a driving unit 31 and a mirror support unit 32 formed on the X1 side of the X-directional optical scanning unit 10, and an X2 side of the X-directional optical scanning unit 10. The drive part 33 and the mirror support part 34 which were formed are provided. The drive units 31 and 33 and the mirror support units 32 and 34 are formed so as to extend linearly in the Y direction. The drive units 31 and 33 have a width W1 in the X direction and a length L1 in the Y direction.

  As shown in FIGS. 5 and 6, the drive units 31 and 33 have a structure in which the piezoelectric actuator 50 is formed on the upper surface (the surface on the Z1 side) of the Si substrate 3. The piezoelectric actuator 50 has a structure in which a lower electrode 41, a piezoelectric body 42, and an upper electrode 51 are laminated from the Si substrate 3 side (Z2 side). The lower electrode 41 is an example of the “first electrode” in the present invention, and the upper electrode 51 is an example of the “second electrode” in the present invention.

  Further, as shown in FIG. 2, the piezoelectric actuator 50 is formed on the entire drive units 31 and 33. That is, the lower electrode 41 and the piezoelectric body 42 (see FIG. 6) are formed so as to extend linearly along the Y direction from the Y1 end 31a to the Y2 end 31b of the drive unit 31. The drive portion 33 is formed to extend linearly from the Y1 side end portion 33a to the Y2 side end portion 33b. Further, the lower electrode 41 and the piezoelectric body 42 of the piezoelectric actuator 50 have the same structure as the lower electrode 41 and the piezoelectric body 42 of the piezoelectric actuator 40 of the inner drive units 16 and 17. The upper electrode 51 is made of a conductive metal material such as Al, Cr, Cu, Au, or Pt.

  Here, in the present embodiment, as shown in FIG. 5, the upper electrode 51 is laminated on the upper surface (Z1 side surface) of the piezoelectric body 42 in a state of being divided into a plurality of parts. Specifically, the upper electrode 51 is divided into seven divided electrodes 51 a to 51 g and is formed on the entire drive units 31 and 33. As shown in FIG. 4, each of the divided electrodes 51a to 51g is formed so as to extend linearly along the Y direction from the Y1 side end 31a to the Y2 side end 31b of the drive unit 31. At the same time, the drive portion 33 is formed to extend linearly along the Y direction from the Y1 side end portion 33a to the Y2 side end portion 33b. That is, the divided electrodes 51a to 51g have a length L1 in the Y direction.

  Further, as shown in FIG. 1, the divided electrodes 51 a to 51 g of the drive units 31 and 33 are each connected to the applied voltage control unit 1. As a result, the applied voltage control unit 1 individually switches the divided electrodes 51a to 51g of the drive units 31 and 33 between a state where a substantially constant voltage is applied and a state where no voltage is applied. Is configured to be possible. As a result, when the drive units 31 and 33 are driven, the number of divided electrodes 51a to 51g to which a voltage is applied among the divided electrodes 51a to 51g can be increased and decreased at regular intervals. ing.

  In the present embodiment, as shown in FIGS. 4 and 5, the divided electrodes 51 a to 51 g are arranged along the X direction with a gap 51 h therebetween, and extend in the Y direction of the drive units 31 and 33. Arranged so as to be substantially symmetrical with respect to center lines R3 and R4. Specifically, the divided electrode 51a is disposed so that the center lines R3 and R4 of the drive units 31 and 33 pass through the center in the X direction. The divided electrode 51a has a width W2 in the X direction. Further, the divided electrodes 51b and 51c are arranged on the X1 side and the X2 side of the divided electrode 51a via the gap 51h, respectively. Each of the divided electrodes 51b and 51c has a width W3 in the X direction. The divided electrode 51a is an example of the “first divided electrode” in the present invention, and the divided electrodes 51b and 51c are examples of the “second divided electrode” in the present invention.

  A divided electrode 51d is disposed on the X1 side of the divided electrode 51b via a gap 51h. A divided electrode 51e is disposed on the X2 side of the divided electrode 51c via a gap 51h. The divided electrodes 51d and 51e each have a width W3 in the X direction. A divided electrode 51f is disposed on the X1 side of the divided electrode 51d via a gap 51h. A divided electrode 51g is arranged on the X2 side of the divided electrode 51e via a gap 51h. Each of the divided electrodes 51f and 51g has a width W3 in the X direction. The divided electrode 51 f is located at the end portion on the X1 side of the piezoelectric body 42 of the piezoelectric actuator 50, and the divided electrode 51 g is located at the end portion on the X2 side of the piezoelectric body 42 of the piezoelectric actuator 50. The divided electrodes 51d and 51e are examples of the “third divided electrode” of the present invention, and the divided electrodes 51f and 51g are examples of the “fourth divided electrode” of the present invention.

  Further, the width W2 in the X direction of the divided electrodes 51a is configured to be approximately twice the width W3 in the X direction of the divided electrodes 51b to 51g. Thereby, as shown in FIG. 4, the electrode areas (W3 × L1) of the divided electrodes 51b to 51g are configured to be approximately half of the electrode area (W2 × L1) of the divided electrode 51a. Note that the width in the X direction of the gap 51h is very small compared to the width W1 in the X direction of the drive units 31 and 33, the width W2 in the X direction of the divided electrodes 51a, and the width W3 in the X direction of the divided electrodes 51b to 51g. It is comprised so that it may become.

  As shown in FIGS. 1 and 2, the Y1 side end 31a of the drive unit 31 and the Y1 side end 33a of the drive unit 33 are fixed by an unshown outer frame body. That is, each of the drive units 31 and 33 is a piece having the end portions 31a and 33a as fixed ends and the end portion 31b on the Y2 side of the drive portion 31 and the end portion 33b on the Y2 side of the drive portion 33 as free ends. It has a cantilevered structure. As a result, when the drive units 31 and 33 are driven, the end portions 31b and 33b are displaced in the Z direction (see FIG. 1) by being deformed so that the drive units 31 and 33 are warped. It is configured to be.

  Further, a connection portion 31c is provided in the vicinity of the end portion 31b on the Y2 side of the drive portion 31. The drive unit 31 is connected to a connection part 32b in the vicinity of the end part 32a on the Y2 side of the mirror support part 32 at the connection part 31c. Further, a connecting portion 33c is provided in the vicinity of the Y2 side end portion 33b of the driving portion 33. The drive unit 33 is connected to a connection part 34b in the vicinity of the Y2 side end 34a of the mirror support part 34 at the connection part 33c.

  Moreover, the mirror support parts 32 and 34 are comprised so that it may not bend substantially. Thereby, the mirror support part 32 is comprised so that it may incline with a predetermined inclination angle in the drive state of the drive part 31. FIG. Similarly, the mirror support portion 34 is configured to be inclined at a predetermined inclination angle in the drive state of the drive portion 33.

  Further, the mirror support portion 32 is connected at the end portion 32c on the Y1 side in the vicinity of the end portion on the X1 side of the side surface on the Y2 side of the frame body 20 of the X direction optical scanning unit 10. Further, the mirror support portion 34 is connected in the vicinity of the end portion on the X2 side of the side surface on the Y2 side of the frame body 20 of the X direction optical scanning portion 10 at the end portion 34c on the Y1 side. Thus, the X-direction optical scanning unit 10 is configured to be inclined at a predetermined inclination angle similarly to the mirror support units 32 and 34.

  Next, with reference to FIG. 1, FIG. 4, FIG. 5 and FIG. 7, control of the voltage to the piezoelectric actuator 50 according to one embodiment of the present invention will be described.

  When applying a voltage to the drive units 31 and 33, as shown in FIG. 5, as a first stage, the applied voltage control unit 1 (see FIG. 1) has a predetermined interval between the divided electrode 51a and the lower electrode 41. And the application of the voltage V is maintained. And after applying a voltage between the division | segmentation electrode 51a and the lower electrode 41, and predetermined time passes, as a 2nd step, the applied voltage control part 1 is between the division | segmentation electrode 51b and the lower electrode 41, and division | segmentation electrode. A predetermined voltage V is applied between 51c and the lower electrode 41, and the application of the voltage V is maintained.

  Then, after a predetermined time has elapsed after applying a voltage between the divided electrode 51b and the lower electrode 41 and between the divided electrode 51c and the lower electrode 41, the applied voltage control unit 1 A predetermined voltage V is applied between 51d and the lower electrode 41 and between the divided electrode 51e and the lower electrode 41, and the application of the voltage V is maintained. Finally, after a predetermined time has elapsed since a voltage was applied between the divided electrode 51d and the lower electrode 41 and between the divided electrode 51e and the lower electrode 41, as a fourth stage, the applied voltage control unit 1 A predetermined voltage V is applied between the electrode 51f and the lower electrode 41 and between the divided electrode 51g and the lower electrode 41, and the application of the voltage V is maintained. That is, the applied voltage control unit 1 sequentially applies the voltage V from the divided electrodes 51a on the center line R3 and R4 side of the piezoelectric bodies 42 of the drive units 31 and 33 toward the divided electrode 51f on the X1 side and the divided electrode 51g on the X2 side. The piezoelectric actuator 50 of the drive units 31 and 33 is gradually deformed by sequentially increasing the number of the divided electrodes 51a to 51g to which the voltage V is applied by holding the applied state.

  On the other hand, when releasing the voltage applied to the drive units 31 and 33 from the state where the voltage is applied to the drive units 31 and 33, as shown in FIG. 1 (see FIG. 1) releases a predetermined voltage V applied between the divided electrode 51f and the lower electrode 41 and between the divided electrode 51g and the lower electrode 41. Then, after the predetermined voltage V applied between the divided electrode 51f and the lower electrode 41 and between the divided electrode 51g and the lower electrode 41 is released and a predetermined time elapses, the applied voltage is set as a second stage. The control unit 1 releases the predetermined voltage V applied between the divided electrode 51d and the lower electrode 41 and between the divided electrode 51e and the lower electrode 41.

  Then, after the predetermined voltage V applied between the divided electrode 51d and the lower electrode 41 and between the divided electrode 51e and the lower electrode 41 is canceled and a predetermined time has elapsed, the applied voltage is set as a third stage. The control unit 1 releases a predetermined voltage V applied between the divided electrode 51b and the lower electrode 41 and between the divided electrode 51c and the lower electrode 41. Finally, after the predetermined voltage V applied between the divided electrode 51b and the lower electrode 41 and between the divided electrode 51c and the lower electrode 41 is released and a predetermined time elapses, the fourth stage is applied. The voltage controller 1 cancels the predetermined voltage V applied between the divided electrode 51a and the lower electrode 41. That is, the applied voltage control unit 1 sequentially releases the voltage V held from the divided electrode 51f on the X1 side and the divided electrode 51g on the X2 side toward the divided electrode 51a on the center line R3 and R4 side, thereby By sequentially decreasing the number of divided electrodes 51a to 51g to which the piezoelectric actuator 50 is applied, the piezoelectric actuators 50 of the drive units 31 and 33 are gradually returned to the undeformed state.

  Here, in the present embodiment, as shown in FIG. 4, the electrode areas (W3 × L1) of the divided electrodes 51b to 51g are configured to be about half of the electrode area (W2 × L1) of the divided electrode 51a. Therefore, the total of the electrode area (W2 × L1) of the divided electrode 51a to which the voltage V is applied in the first stage and the electrode area of the divided electrodes 51b and 51c to which the voltage V is applied in the second stage (2 × (W3 × L1) = (W2 × L1)) and the sum of the electrode areas of the divided electrodes 51d and 51e to which the voltage V is applied in the third stage (2 × (W3 × L1) = (W2 × L1)) The sum of the electrode areas of the divided electrodes 51f and 51g to which the voltage V is applied in the fourth stage (2 × (W3 × L1) = (W2 × L1)) is substantially equal.

  Similarly, the electrode areas of the divided electrodes 51f and 51g from which the voltage V applied in the first stage is released, and the electrode areas of the divided electrodes 51d and 51e from which the voltage V applied in the second stage is released. The total of the electrode area of the divided electrodes 51b and 51c from which the voltage V applied in the third stage is released and the electrode area of the divided electrode 51a from which the voltage V applied in the fourth stage is released Both are substantially equal. That is, the number of the divided electrodes 51a to 51g to which the voltage is applied is sequentially increased or decreased so that the total area of the divided electrodes 51a to 51g to which the voltage is applied is sequentially increased or decreased with a substantially constant size (W2 × L1). Decrease.

  As a result, as shown in FIG. 7, the hysteresis characteristics of the respective divided electrodes 51a to 51g still remain, but the upper electrode 51 is divided into a plurality of divided parts as compared with the comparative example (one-dotted line) in which the upper electrode 51 is not divided. In the present embodiment divided into the electrodes 51a to 51g, the non-linear deformation caused by the hysteresis characteristic in the piezoelectric body 42 of the piezoelectric actuator 50 is dispersed in four stages by the control by the applied voltage control unit 1. That is, unlike the case where the piezoelectric body 42 is deformed by the total displacement amount by one voltage application, the piezoelectric body 42 is gradually deformed by small displacement amounts obtained by dividing the total displacement amount of the piezoelectric body 42 into four, It becomes possible to reach the deformation for the total displacement. Further, unlike the case where the piezoelectric body 42 to which the voltage is applied is returned to the deformation of the total displacement amount by releasing the voltage once, the small displacement amount obtained by dividing the total displacement amount of the piezoelectric body 42 into four is gradually increased. It is possible to return the deformation of the piezoelectric body 42 to the total displacement amount. Thereby, both the increase of the displacement amount (product of the voltage and the total area of the divided electrodes to which the voltage is applied) with respect to the applied voltage V and the decrease of the displacement amount with respect to the released voltage V are both linear.

  Next, the driving operation of the Y-direction optical scanning unit 30 of the optical scanning device 100 according to an embodiment of the present invention will be described with reference to FIGS.

  From the state where the drive units 31 and 33 as shown in FIG. 1 are kept horizontal by being in the non-drive state, the applied voltage control unit 1 is connected to the drive units 31 and 33 as piezoelectric actuators as shown in FIG. When a voltage that causes the upper surface side (Z1 side) of 50 to contract more than the lower surface side (Z2 side) is applied based on the voltage control described above, the upper surface side (Z1 side) of the drive units 31 and 33 It contracts more than the side (Z2 side).

  Thereby, in the drive part 31, the drive part 31 warps upwards because the edge part 31b by the side of Y2 which is a free end is located above the edge part 31a by the side of Y1 which is a fixed end (Z1 side). It is deformed as follows. At this time, as shown in FIG. 9, the inclination angle of the end portion (free end) 31b of the drive portion 31 in the B1 direction is θ1 with respect to the tangent C1 at the end portion (fixed end) 31a. Similarly, in the drive unit 33, the end portion 33b on the Y2 side, which is a free end, is positioned above the end portion 33a on the Y1 side, which is a fixed end, so that the drive unit 33 is deformed to warp upward. The At this time, the inclination angle of the end portion (free end) 33b of the drive unit 33 in the B1 direction is θ1 with respect to the tangent C2 at the end portion (fixed end) 33a.

  As a result, as shown in FIG. 9, the mirror support portion 32 connected to the Y2 side connection portion 31c of the drive portion 31 maintains the inclination angle θ1 of the end portion 31b of the drive portion 31 with respect to the tangent line C1. Inclined in the B1 direction without bending. Similarly, the mirror support portion 34 connected to the Y2 side connection portion 33c of the drive portion 33 maintains the inclination angle θ1 of the end portion 33b of the drive portion 33 with respect to the tangent line C2 and is not bent when B1 is maintained. Tilted in the direction. Accordingly, the X-direction optical scanning unit 10 (mirror 11) is supported by the mirror support unit 32 on the X1 side and the Y2 side, and supported by the mirror support unit 34 on the X2 side and the Y2 side. ) Is inclined in the B1 direction at an inclination angle θ1 with respect to the tangent lines C1 and C2 in the same manner as the mirror support portions 32 and 34.

  Further, the drive units 31 and 33 of the Y-direction optical scanning unit 30 are nonresonantly driven in a direction in which the upper surface side (Z1 side) of the piezoelectric actuator 50 is contracted more than the lower surface side (Z2 side) at a frequency of about 60 Hz. A voltage is applied to. As a result, the X-direction optical scanning unit 10 (mirror 11) is tilted at the tilt angle θ1 of FIGS. 8 and 9 from the horizontal state of FIG. 1 and then returned to the horizontal state of FIG. By repeating this series of deformation operations, the drive units 31 and 33 and the mirror support units 32 and 34 cause the mirror 11 to tilt in the B1 direction around the rotation center R2 and scan light in the Y direction.

  In the present embodiment, as described above, the upper electrode 51 is divided into a plurality of divided electrodes 51a to 51g, and the applied voltage control unit 1 sequentially increases the number of divided electrodes 51a to 51g to which a voltage is applied. Unlike the case where the piezoelectric body 42 is deformed by the total displacement amount by applying a single voltage, the piezoelectric body 42 is configured to be deformed, and gradually the small displacement amount obtained by dividing the total displacement amount of the piezoelectric body 42 is gradually increased. The piezoelectric body 42 can be deformed to reach the deformation for the entire displacement amount. Similarly, the upper electrode 51 is divided into a plurality of divided electrodes 51a to 51g, and the applied voltage control unit 1 is configured to return the deformation of the entire displacement amount by one voltage application. Unlike the case where the piezoelectric body 42 to which the voltage is applied is returned to the deformation amount of the total displacement amount by releasing the voltage once, the piezoelectric body 42 is gradually increased by the small displacement amount obtained by dividing the total displacement amount of the piezoelectric body 42. The deformation of the total displacement amount can be returned by returning the deformation. As a result, the non-linear deformation caused by the hysteresis characteristic of the piezoelectric body 42 (characteristic in which the displacement amount with respect to the applied voltage increases nonlinearly and the displacement amount with respect to the released voltage decreases nonlinearly) is dispersed. Therefore, non-linear deformation due to the hysteresis characteristics of the piezoelectric body 42 can be mitigated. Thereby, the X direction optical scanning part 10 (mirror 11) can be rotated stably.

  In the present embodiment, as described above, the applied voltage control unit 1 applies a substantially constant voltage (voltage V) to the divided electrodes 51a to 51g of the drive units 31 and 33. In addition, by individually switching to a state in which no voltage is applied, the number of divided electrodes 51a to 51g to which a voltage is applied can be increased and decreased at regular intervals, thereby taking hysteresis characteristics into consideration. Compared with the case where the applied voltage control unit 1 controls the voltage magnitude, the voltage magnitude is substantially constant (voltage V), and it is not necessary to control the voltage magnitude, so that complicated control is performed. Therefore, the non-linear deformation caused by the hysteresis characteristic of the piezoelectric body 42 can be dispersed and relaxed more easily.

  Further, in the present embodiment, as described above, the division in which the voltage is applied so that the sum of the areas of the divided electrodes 51a to 51g to which the voltage is applied is sequentially increased or decreased with a substantially constant size (W2 × L1). Unlike the case where the total of the areas of the divided electrodes 51a to 51g to which the voltage is applied is sequentially increased or decreased by the configuration in which the number of the electrodes 51a to 51g is sequentially increased or decreased, the voltage is applied. When the number of the divided electrodes 51a to 51g is sequentially increased or decreased, the piezoelectric body 42 can be deformed so as to always increase or decrease by substantially the same amount of deformation, so that the deformation of the piezoelectric body 42 can be made closer to linear. it can. Thereby, the piezoelectric actuator 50 can be driven more stably.

  In the present embodiment, as described above, the divided electrodes 51a are arranged at positions substantially centering on the center lines R3 and R4 extending in the Y direction of the drive units 31 and 33, and the X1 side and the X2 side of the divided electrodes 51a The divided electrodes 51b and 51c are respectively disposed, the divided electrode 51d is disposed on the X1 side of the divided electrode 51b, the divided electrode 51e is disposed on the X2 side of the divided electrode 51c, and the divided electrode is disposed on the X1 side of the divided electrode 51d. 51f is arranged, the divided electrode 51g is arranged on the X2 side of the divided electrode 51e, and the electrode area (W2 × L1) of the divided electrode 51a and the total electrode area of the pair of second divided electrodes (2 × (W3 × L1)), the total electrode area of the pair of third divided electrodes (2 × (W3 × L1)), and the total electrode area of the pair of fourth divided electrodes (2 × (W3 × L1)) By making equal The piezoelectric body 42 in a state close to a state where the displacement amount with respect to the applied voltage increases linearly with a proportional relationship and a state where the displacement amount with respect to the released voltage decreases linearly with a proportional relationship. Can be deformed. In addition, since the piezoelectric actuator 50 can be prevented from inclining along the X direction without performing complicated control by the applied voltage control unit 1, the piezoelectric actuator 50 can be driven more stably. Further, by increasing the number of the divided electrodes 51a to 51g, the piezoelectric body 42 can be deformed in a state where the influence of the hysteresis characteristic of the piezoelectric body 42 is further dispersed.

  In the present embodiment, as described above, the applied voltage control unit 1 is configured such that the divided electrodes 51f at the end on the X1 side from the divided electrodes 51a on the center line R3 and R4 side of the piezoelectric body 42 of the driving units 31 and 33 and By sequentially applying a voltage toward the divided electrode 51g at the end on the X2 side and maintaining the applied state, the number of divided electrodes 51a to 51g to which the voltage is applied is sequentially increased, thereby driving units 31 and 33. Unlike the case where the voltage applied to any of the divided electrodes 51a to 51g among the plurality of divided electrodes 51a to 51g is maintained, the center line R3 is configured by deforming the piezoelectric actuator 50. The piezoelectric body 42 is sequentially deformed from the split electrode 51a on the R4 side toward the split electrode 51f on the end portion on the X1 side and the split electrode 51g on the end portion on the X2 side. It is possible. Furthermore, by making the total area of the divided electrodes 51a to 51g to which the voltage is sequentially applied substantially the same (W2 × L1), the piezoelectric body 42 is made substantially uniform so as to be substantially symmetrical with respect to the center lines R3 and R4. Can be deformed. Thereby, the piezoelectric actuator 50 can be driven more stably.

  In the present embodiment, as described above, the applied voltage control unit 1 holds the divided electrode 51f on the X1 side and the divided electrode 51g on the X2 side toward the divided electrode 51a on the center line R3 and R4 side. By sequentially decreasing the number of the divided electrodes 51a to 51g to which the voltage is applied by sequentially releasing the voltage, the piezoelectric actuator 50 of the drive units 31 and 33 is returned to the undeformed state, Unlike the case of releasing the voltage of any of the divided electrodes 51a to 51g among the plurality of divided electrodes 51a to 51g, the center line R3 is separated from the divided electrode 51f at the end on the X1 side and the divided electrode 51g at the end on the X2 side. And the deformation of the piezoelectric body 42 can be sequentially released toward the divided electrode 51a on the R4 side. Furthermore, by making the total area of the divided electrodes 51a to 51g for releasing the sequentially applied voltages substantially the same (W2 × L1), the piezoelectric body 42 is substantially symmetrical with respect to the center lines R3 and R4. The deformation can be released substantially uniformly. Thereby, the piezoelectric actuator 50 can be driven more stably.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above-described embodiment, the example in which the piezoelectric actuator 50 in which the upper electrode 51 is divided into the plurality of divided electrodes 51a to 51g is applied to the optical scanning device 100 has been described, but the present invention is not limited thereto. For example, a piezoelectric actuator in which at least one of the first electrode and the second electrode has a plurality of divided electrodes may be used for applications other than an optical scanning device such as a detection unit of a scanning electron microscope.

  Moreover, although the example which divided | segmented the upper electrode 51 of the piezoelectric actuator 50 of the drive parts 31 and 33 was shown in the said embodiment, this invention is not limited to this. In the present invention, the lower electrode may be divided without dividing the upper electrode of the piezoelectric actuator. Further, both the upper electrode and the lower electrode may be divided. When the lower electrode is divided, the upper electrode may be grounded, and a voltage may be sequentially applied to the divided lower electrodes. Further, when both the upper electrode and the lower electrode are divided, any one of the divided upper electrode and the divided lower electrode may be grounded, and a voltage may be sequentially applied to the other one by one. Further, the offset voltage can be adjusted by connecting the electrode to the voltage applying means without grounding the electrode.

  Moreover, in the said embodiment, although the example which divided | segmented the upper electrode 51 in the piezoelectric actuator 50 of the drive parts 31 and 33 of the Y direction optical scanning part 30 was shown, this invention is not limited to this. In the present invention, the electrodes may be divided in the piezoelectric actuator of the inner drive unit of the X direction optical scanning unit.

  In the above-described embodiment, the divided electrodes 51a to 51g to which the voltage is applied are sequentially increased or decreased so that the total area of the divided electrodes 51a to 51g to which the voltage is applied is substantially constant (W2 × L1). Although an example in which the number is sequentially increased or decreased is shown, the present invention is not limited to this. In the present invention, the number of divided electrodes to which the voltage is applied may be sequentially increased or decreased so that the total area of the divided electrodes to which the voltage is applied is sequentially increased or decreased with different sizes.

  In the above embodiment, the example in which the divided electrodes 51a to 51g are arranged so as to be substantially symmetric with respect to the center lines R3 and R4 extending in the Y direction of the drive units 31 and 33 has been described. Not limited. In the present invention, the divided electrodes may be arranged so as to be asymmetric with respect to a center line extending in the Y direction of the drive unit.

  Further, in the above embodiment, the applied voltage control unit 1 is directed from the divided electrodes 51a on the center line R3 and R4 side of the piezoelectric body 42 of the drive units 31 and 33 to the divided electrode 51f on the X1 side and the divided electrode 51g on the X2 side. The applied voltage control unit 1 holds the applied voltage control unit 1 from the divided electrode 51f on the X1 side and the divided electrode 51g on the X2 side toward the divided electrode 51a on the center line R3 and R4 side. Although the example which cancels | releases the voltage which was done one by one was shown, this invention is not limited to this. For example, contrary to the above-described embodiment, the control unit holds the state in which a voltage is sequentially applied from the X1 side divided electrode and the X2 side divided electrode toward the centerline side divided electrode and the piezoelectric element is applied. You may comprise so that the voltage currently hold | maintained toward the division | segmentation electrode by the side of the X1 side and the division | segmentation electrode by the side of X2 may be cancelled | released one by one. In addition, the control unit may apply and hold the voltage to the divided electrode at any position where no voltage is applied, or release the voltage of any divided electrode among the divided electrodes to which the voltage is applied. May be.

Moreover, although the piezoelectric body 42 showed the example which consists of lead zirconate titanate (PZT) in the said embodiment, this invention is not limited to this. For example, it may be formed of a piezoelectric material made of an oxide mainly composed of lead, titanium and zirconium other than PZT, or other piezoelectric materials. Specifically, the piezoelectric body includes zinc oxide (ZnO), lead lanthanum zirconate titanate ((Pb, La) (Zr, Ti) O ₃ ), potassium niobate (KNbO ₃ ), sodium niobate (NaNbO). _It may be formed of a piezoelectric material such as ₃ ).

1 Applied voltage controller (voltage application means)
10 X-direction optical scanning unit (mirror unit)
41 Lower electrode (first electrode)
42 Piezoelectric body 50 Piezoelectric actuator 51 Upper electrode (second electrode)
51a Split electrode (first split electrode)
51b, 51c Split electrode (second split electrode)
51d, 51e Split electrode (third split electrode)
51f, 51g Split electrode (fourth split electrode)
100 Optical scanning device R2 Center of rotation R3, R4 Center line

Claims (8)

A piezoelectric body that is formed to extend linearly along the first direction and deforms nonlinearly based on hysteresis characteristics when a voltage is applied;
A first electrode formed on one surface of the piezoelectric body so as to extend linearly from one end side to the other end side in the first direction of the piezoelectric body;
A second electrode formed on the other surface of the piezoelectric body so as to extend linearly from one end side to the other end side in the first direction of the piezoelectric body;
Voltage applying means for applying a voltage to the first electrode and the second electrode,
At least one of the first electrode and the second electrode is divided into a plurality of divided electrodes extending linearly from one end side to the other end side in the first direction of the piezoelectric body,
The voltage applying means can individually apply a voltage to the plurality of divided electrodes, and can deform the piezoelectric body by sequentially increasing or decreasing the number of the divided electrodes to which the voltage is applied. Alternatively, a piezoelectric actuator configured to return deformation of the piezoelectric body.   The voltage applying means switches the divided electrodes to which the voltage is applied by individually switching between a state in which a substantially constant voltage is applied to the plurality of divided electrodes and a state in which no voltage is applied. The piezoelectric actuator of claim 1, wherein the piezoelectric actuator is configured to sequentially increase or decrease the number.   The voltage applying means is configured to sequentially increase or decrease the number of the divided electrodes to which the voltage is applied so that the total area of the divided electrodes to which the voltage is applied is sequentially increased or decreased with a substantially constant size. The piezoelectric actuator according to claim 1, wherein the piezoelectric actuator is provided.   The plurality of divided electrodes are disposed so as to be substantially symmetrical with respect to a center line extending in the first direction through the center of the piezoelectric body in a second direction substantially orthogonal to the first direction. Item 4. The piezoelectric actuator according to any one of Items 1 to 3.   The plurality of divided electrodes are respectively disposed on a first divided electrode through which a center line of the piezoelectric body passes through a center in the second direction and on both sides of the first divided electrode in the second direction. 5. The piezoelectric actuator according to claim 4, comprising a pair of second divided electrodes having a substantially half area.   The plurality of divided electrodes are respectively disposed on opposite sides of the pair of second divided electrodes in the second direction from the first divided electrodes, and have a pair of third areas having approximately half the area of the first divided electrodes. A pair of fourth divided electrodes disposed on opposite sides of the pair of third divided electrodes in the second direction with respect to the first divided electrode and having an area approximately half of that of the first divided electrode; The piezoelectric actuator according to claim 5, further comprising:   The voltage applying means is configured to sequentially apply and apply a voltage from the divided electrode on the center line side of the piezoelectric body toward the divided electrodes on both ends in the second direction substantially orthogonal to the first direction. By holding, the piezoelectric body is deformed by sequentially increasing the number of the divided electrodes to which the voltage is applied, and from the divided electrodes on both ends in the second direction to the center line side of the piezoelectric body. The configuration is such that the deformation of the piezoelectric body is restored by sequentially decreasing the number of the divided electrodes to which a voltage is applied by sequentially releasing the voltage held toward the divided electrodes. The piezoelectric actuator according to any one of 1 to 6. A piezoelectric body that is formed to extend linearly along the first direction and deforms nonlinearly based on hysteresis characteristics when a voltage is applied;
A first electrode formed on one surface of the piezoelectric body so as to extend linearly from one end side to the other end side in the first direction of the piezoelectric body;
A second electrode formed on the other surface of the piezoelectric body so as to extend linearly from one end side to the other end side in the first direction of the piezoelectric body;
A piezoelectric actuator including voltage applying means for applying a voltage to the first electrode and the second electrode;
A mirror portion rotated about the rotation center by the piezoelectric actuator,
At least one of the first electrode and the second electrode is divided into a plurality of divided electrodes extending linearly from one end side to the other end side in the first direction of the piezoelectric body,
The voltage applying means can individually apply a voltage to the plurality of divided electrodes, and can deform the piezoelectric body by sequentially increasing or decreasing the number of the divided electrodes to which the voltage is applied. Alternatively, an optical scanning device configured to return deformation of the piezoelectric body.

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