JP4744636B1 - Drive device, image acquisition device, and electronic apparatus - Google Patents

Abstract

A driving device capable of securing a sufficient displacement level by low-voltage driving is provided.
A drive device includes a drive shaft, a piezoelectric element fixed to one end of the drive shaft, and expands and contracts in response to application of a drive voltage, and a shaft holding portion that holds the drive shaft slidably in the axial direction. A drive voltage generation circuit 81 that generates a drive voltage to be applied to the piezoelectric element 42. The drive voltage generation circuit 81 includes a first drive circuit that applies a drive voltage from one electrode of the piezoelectric element 42, and a second drive circuit that applies a drive voltage from the other side of the piezoelectric element 42. An AC drive voltage is generated by switching between the drive circuit and the second drive circuit. Inductive elements 91 and 92 are provided at the output stage of the first drive circuit and the output stage of the second drive circuit. The frequency of the drive voltage is selected from a frequency range in which the gain is greater than zero dB due to the interaction of the switch resistance, the capacitance of the piezoelectric element 42, and the inductance of the inductive elements 91 and 92 included in the first and second drive circuits.
[Selection] Figure 11

Description

  The present invention relates to a drive device, an image acquisition device, and an electronic apparatus.

  In recent years, cameras have been incorporated into a wide variety of products. When a camera is mounted on a small electronic device such as a mobile phone or a laptop computer, it is strongly required to reduce the size of the camera itself.

An autofocus lens may be incorporated in the camera. In this case, downsizing of the actuator that displaces the lens is strongly desired.
As a small actuator, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2000-350482) discloses a piezoelectric actuator (driving device) that applies a voltage to a piezoelectric element and displaces the lens by vibration generated in the piezoelectric element. .
FIG. 30 is a diagram showing a configuration of the piezoelectric actuator disclosed in Patent Document 1. In FIG.

  The piezoelectric actuator 100 includes a piezoelectric element 101, a rod-like drive member 102 driven by the piezoelectric element 101, an engagement member 103 frictionally engaged with the drive member 102 with a predetermined frictional force, and a drive to the piezoelectric element 101. And a drive circuit 104 for applying a voltage. The piezoelectric element 101 expands and contracts according to the drive voltage applied by the drive circuit 104, and one end of the piezoelectric element is fixed to one end of the drive member 102. The other end of the piezoelectric element 101 is fixed to a support member 120 that is a fixed side member. The engaging member 103 is movable on the driving member 102 along the axial direction. A photographing lens L that is a driving object is fixed to the engaging member 103. By moving the engaging member 103, the photographing lens L is moved together with the engaging member 103.

Next, FIG. 31 is a circuit diagram showing a configuration of the drive circuit 104 disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2000-350482).
As shown in FIG. 31, the drive circuit 104 is composed of an H-type bridge circuit.
The drive circuit 104 includes a pMOSFET 111 and a pMOSFET 113 that are drive P-channel FETs (field effect transistors), and an nMOSFET 115 and an nMOSFET 114 that are drive N-channel FETs.
The pMOSFET 111 and the pMOSFET 113 are turned on when the gate voltage is 0 [V], and are turned off when the gate voltage is E [V]. The nMOSFET 112 and the nMOSFET 114 are cut off when the gate voltage is 0 [V], and are turned on when the gate voltage is E [V].
The control terminals (gates) of the FETs 111 to 114 are connected to the control circuit 104a, and are controlled to be switched between the conductive state and the cutoff state of the FETs 111 to 114 in response to a control signal from the control circuit 104a.
Further, the drive circuit 104 has an inductive element 146 connected in series with the piezoelectric element 101.

FIG. 32 is a timing chart showing an operation sequence of the drive circuit 104.
For example, in period A, the gate voltage of pMOSFET 113 is E [V], the gate voltage of pMOSFET 111 is 0 [V], the gate voltage of nMOSFET 114 is 0 [V], and the gate voltage of nMOSFET 112 Is E [V]. Therefore, pMOSFET 111 and nMOSFET 112 are in a conductive state, and pMOSFET 113 and nMOSFET 114 are in a cut-off state. In this case, as shown in FIG. 33, E [V] is applied to one electrode of the piezoelectric element via the pMOSFET 111, and the ground potential (0V) is applied to the other electrode via the nMOSFET 112. .

  In period B after period A, the gate voltage of pMOSFET 113 is 0 [V], the gate voltage of pMOSFET 111 is E [V], and the gate voltage of nMOSFET 114 is E [V]. The gate voltage of the nMOSFET 112 is 0 [V]. Therefore, pMOSFET 113 and nMOSFET 114 are turned on, and pMOSFET 111 and nMOSFET 112 are cut off. In this case, as shown in FIG. 34, the ground potential (0 V) is applied to one electrode of the voltage element 101 via the nMOSFET 114, and E [V] is applied to the other electrode via the pMOSFET 113. The In this way, an AC voltage twice as large as the power supply voltage E is applied to both ends of the piezoelectric element 101.

FIG. 35 shows another example of the operation sequence. The difference from FIG. 32 is that the electric charge charged in the piezoelectric element 101 is once discharged and then reversely charged.
The period A and the period B in FIG. 35 have the same operation pattern as the period A and the period B shown in FIG.
In the period C in FIG. 35, since all gate voltages of the FETs 111 to 114 are E (V), the FET 111 and the FET 113 are in a cut-off state, and the FET 112 and the FET 114 are in a conductive state.
Therefore, the voltage across the piezoelectric element 101 is short-circuited. Then, the charge charged in the piezoelectric element 101 in the period A is temporarily discharged in the period C, and in the period B, it is charged in a direction opposite to the charging direction in the period A.

  When a voltage whose polarity is reversed as described above is applied to the piezoelectric element 101, the piezoelectric element 101 performs expansion and contraction in the thickness direction. Then, as shown in FIGS. 30 (b) and 30 (c), the lens L can be displaced using this expansion and contraction motion.

Further, since the drive circuit 104 includes the inductive element 146, a counter electromotive force is generated by the inductive element 146 during the period C. Due to the action of the counter electromotive force, an electromotive force opposite to the discharge direction can be obtained. As a result, the piezoelectric element 101 is charged in the direction opposite to the discharge direction, and the amount of charge to be additionally supplemented in the period B is reduced.
Patent Document 1 discloses that such a drive circuit configuration can reduce current consumption.

JP 2000-350482 A

In recent years, there has been a demand for further miniaturization of piezoelectric actuators used in small camera modules.
In order to realize miniaturization of the piezoelectric actuator, it is required to reduce the number of stacked piezoelectric elements to further reduce the height in the height direction.
Here, when the number of stacked layers is reduced, the displacement vibration level of the piezoelectric element is reduced, and there arises a problem that a sufficient driving ability cannot be ensured or a stable operation is difficult to obtain. Therefore, it is conceivable to increase the applied voltage in order to sufficiently vibrate the miniaturized piezoelectric element.
However, considering that the small piezoelectric actuator is mounted on a small portable electronic device, low voltage driving and low power consumption are also required at the same time. Therefore, a method such as simply using the boosted voltage cannot be employed.

  An object of the present invention is to provide a drive device that can ensure a sufficient displacement level even in low-voltage drive.

The drive device of the present invention is
A fixed side member;
A slide body movably engaged with the fixed side member;
A piezoelectric element that is fixed to the slide body and expands and contracts in response to application of a driving voltage;
A drive voltage generation circuit for generating a drive voltage to be applied to the piezoelectric element,
The drive voltage generation circuit includes a first drive circuit that applies a drive voltage from one side electrode of the piezoelectric element, and a second drive circuit that applies a drive voltage from the other side of the piezoelectric element. Generating alternating drive voltage for expanding and contracting the piezoelectric element by switching between 1 drive circuit and the second drive circuit;
Each of the output stage of the first drive circuit and the output stage of the second drive circuit has an inductive element,
The frequency of the drive voltage is
It is preferable to select from a frequency range in which the gain is greater than zero dB by the interaction of the switch resistance included in the first and second drive circuits, the capacitance of the piezoelectric element, and the inductance of the inductive element.

In the present invention,
The frequency of the drive voltage is
It is preferable to select from a frequency range in which the gain is greater than 2 dB by the interaction of the switch resistance included in the first and second drive circuits, the capacitance of the piezoelectric element, and the inductance of the inductive element.

In the present invention,
The frequency of the drive voltage is
The frequency range in which the gain is greater than zero by the interaction of the switch resistance included in the first and second drive circuits, the capacitance of the piezoelectric element, and the inductance of the inductive element, and the resonance point It is preferable to select 10% before and after the frequency from the excluded frequency range.

In the present invention,
The frequency of the drive voltage is
The frequency range in which the gain is greater than zero by the interaction of the switch resistance included in the first and second drive circuits, the capacitance of the piezoelectric element, and the inductance of the inductive element, and the resonance point It is preferable to select from a frequency range smaller than the frequency.

In the present invention,
The slide body has a lens holding body for holding a lens, and a drive shaft connected to the lens holding body,
The piezoelectric element is fixed to one end of the drive shaft,
The drive shaft is preferably held so as to be slidable in the axial direction by a shaft holding portion as the fixed side member.

In the present invention,
The piezoelectric element, the drive shaft and the lens holder are integrated,
The piezoelectric element preferably moves together with the drive shaft and the lens holder relative to the shaft holding portion.

The drive device of the present invention is
A fixed side member;
A slide body movably engaged with the fixed side member;
A piezoelectric element that is fixed to the slide body and expands and contracts in response to application of a driving voltage;
A drive voltage generation circuit for generating a drive voltage to be applied to the piezoelectric element,
The drive voltage generation circuit includes:
A first dielectric element provided on one electrode side of the piezoelectric element;
A second dielectric element provided on the other electrode side of the piezoelectric element;
A first drive circuit for applying a positive drive voltage to the piezoelectric element via the first dielectric element and the second dielectric element;
A second drive circuit for applying a negative drive voltage to the piezoelectric element through the first dielectric element and the second dielectric element,
By switching between the first drive circuit and the second drive circuit, an alternating drive voltage for expanding and contracting the piezoelectric element is generated.

In the present invention,
The drive voltage generation circuit is an H bridge circuit,
A coupling line connecting between the first output terminal and the second output terminal of the H-bridge circuit;
The piezoelectric element is disposed in the middle of the coupling line,
The coupling line is preferably provided with two dielectric elements with the piezoelectric element in between.

An image acquisition apparatus according to the present invention includes the driving device and an imaging unit that acquires an image input through the lens.
An electronic apparatus according to the present invention includes the image acquisition device.

The perspective view of a camera module. The exploded perspective view of a camera module. The perspective view of a lens unit. The top view of a camera module. Sectional drawing in the VV line in FIG. Sectional drawing of a lens unit. The disassembled perspective view of a shaft holding part. Sectional drawing of a shaft holding part. The top view which shows the state which attached the axial holding | maintenance part to the housing | casing. The functional block diagram of the control system of a drive device. The circuit diagram of a drive voltage generation circuit. 4 is a timing chart showing an operation sequence of a drive voltage generation circuit. FIG. 13 is a diagram showing a current path in period A in FIG. FIG. 13 is a diagram showing a current path in period B in FIG. The figure which shows the relationship between the both-ends voltage of a piezoelectric element, and the movement state of a lens holder. The figure which shows typically the relationship between the expansion-contraction operation | movement of a piezoelectric element, and the movement state of a lens holder. The figure which shows the equivalent circuit of a 1st drive circuit and a 2nd drive circuit. The figure which shows the simulation result of a circuit operation | movement. The figure which extracted the area | region in the middle of a gain rising toward the resonance point peak in FIG. The figure which shows the simulation result of a circuit operation | movement. The figure which shows the simulation result of a circuit operation | movement. The figure for demonstrating that the harmonic component of a drive signal can be suppressed. The figure which shows the example of the drive voltage in which the power line noise carried. The figure which shows the example of the drive voltage which suppressed the power supply line noise by the filter effect. The figure which shows the modification 1. FIG. The figure which shows the modification 2. FIG. FIG. 9 is a diagram for explaining the operation of Modification 2. FIG. 9 is a diagram for explaining the operation of Modification 2. The figure which shows the modification 3. FIG. The figure which shows the structure of the conventional piezoelectric actuator. The circuit diagram which shows the structure of the conventional drive circuit. 9 is a timing chart showing an operation sequence of a conventional drive circuit. FIG. 33 is a diagram showing a current path in period A in FIG. FIG. 33 is a diagram showing a current path in a period B in FIG. 9 is a timing chart showing an operation sequence of a conventional drive circuit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Each embodiment is simplified for convenience of explanation.
Since the drawings are simple, the technical scope of the present invention should not be interpreted narrowly based on the drawings.
The drawings are only for explaining the technical matters, and do not reflect the exact sizes or the like of the elements shown in the drawings.
The same elements are denoted by the same reference numerals, and redundant description is omitted.
Words indicating directions such as up, down, left, and right are used on the assumption that the drawing is viewed from the front.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a camera module.
FIG. 2 is an exploded perspective view of the camera module.
The camera module (image acquisition device) 150 includes a wiring board 10, a connector 11, an image sensor 12, a transparent substrate (flat plate member) 13, a housing (envelope) 20, and a lens unit (lens component) 30. And a lid (envelope) 50.

A connector 11 is disposed at one end of the wiring board 10. On the other end of the wiring substrate 10, an image sensor 12 and a transparent substrate 13 are disposed.
On the image sensor 12, the transparent substrate 13, the housing 20, the lens unit 30, and the lid 50 are arranged in this order.
The housing 20 functions as a stationary member that does not move when viewed from the lenses L1 to L3 (see FIG. 5) that are moving objects.

The wiring board 10 is a flexible sheet-like wiring board.
A control signal is sent to the image sensor 12 through the wiring board 10 and a video signal from the image sensor 12 is transmitted. In addition, the wiring board 10 functions as a transmission path for a drive voltage signal input to a piezoelectric element 42 (described later) in the lens unit 30.

  The connector 11 forms a connection portion for electrically and mechanically fixing the camera module 150 to the main device.

  The image sensor 12 is a general solid-state image sensor such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor. The image sensor 12 has a plurality of pixels arranged in a matrix on the XZ plane. Each pixel performs photoelectric conversion to convert the input image into image data and output it.

  The transparent substrate 13 is a plate-like member that is substantially transparent to input light. The top view shape of the transparent substrate 13 is a square. The image sensor 12 is bump-connected to the back surface of the transparent substrate 13.

  The housing 20 is mounted on the wiring board 10. The housing 20 stores the transparent substrate 13 in the lower space, and stores the lens unit 30 in the upper space. By adopting the housing 20, the camera function can be modularized. In order to suppress the entry of extraneous light into the interior of the housing 20, the lower end surface of the housing 20 is fixed to the wiring board 10 via a black adhesive. The housing 20 is manufactured, for example, by molding a black resin.

The lid 50 is attached to the housing 20. As a result, the lens unit 30 is confined in the housing 20. The lid 50 is preferably attached to the housing 20 by screws. The lid 50 can be attached to and detached from the casing 20 by fixing the lid 50 to the casing 20 with screws instead of adhesively fixing. This makes it possible to remove the cause of the failure of the camera module 150 determined to be defective in the operation test after the test. For example, the yield of the camera module can be improved by removing dust that has entered the imaging surface of the image sensor 12 after the operation test.
The lid 50 is manufactured, for example, by molding a resin.

Next, the lens unit will be described.
FIG. 3 is a perspective view of the lens unit.
4 is a top view of the camera module, and FIG. 5 is a cross-sectional view taken along line VV in FIG.
The lens unit 30 includes a lens holder (holding body) 31, a piezoelectric element 42, a transmission shaft (drive shaft) 44, and a shaft holding portion 45.

The lens holder 31 is a cylindrical member, and holds the lenses L1 to L3 therein. An opening OP2 is formed in the upper plate portion of the lens holder 31, and the upper plate portion of the lens holder 31 functions as an optical stop. A connecting portion 32 is provided on the outer periphery of the lens holder 31, and the transmission shaft 44 is connected and fixed to the connecting portion 32.
Here, the connecting portion 32 is configured by a support plate 32a and a support plate 32b that are spaced apart in the vertical direction, and the transmission shaft 44 is fixedly supported by the support plate 32a and the support plate 32b.
Specifically, the transmission shaft 44 is press-fitted into the openings of the support plates 32a and 32b of the connecting portion 32.
The transmission shaft 44 may be fixedly supported by one of the support plate 32a and the support plate 32b, not limited to such two-point support.

  The shaft holding part 45 is a fixed side member fixed to the lens holder (holding body) 31. The shaft holding portion 45 has a ring-shaped portion 45h1, and the transmission shaft 44 is inserted through the opening of the ring-shaped portion 45h1. At this time, the annular portion 45h1 and the transmission shaft 44 are in frictional engagement with each other. The ring-shaped portion 45h1 of the shaft holding portion 45 is disposed between the support plate 32a and the support plate 32b.

  The detailed configuration of the shaft holding portion will be described later.

The transmission shaft 44 is a rod-like body whose longitudinal direction is the Y-axis direction, and is connected and fixed to the lens holder 31 via the connecting portion 32.
On the other hand, the transmission shaft 44 and the shaft holding portion 45 are in frictional engagement with each other, and the shaft holding portion 45 holds the transmission shaft 44 so as to be slidable along the y-axis.
The transmission shaft 44 is preferably lightweight and highly rigid. The transmission shaft 44 is preferably molded from glassy carbon, fiber reinforced resin, or epoxy resin.
Particularly preferred are glassy carbon composites containing graphite, fiber reinforced resins and glass containing carbon, and epoxy resin composites containing carbon.

The piezoelectric element 42 is a general piezoelectric element in which ceramic layers (piezoelectric layers) are stacked. The side surfaces of the piezoelectric element 42 function as a pair of electrode terminals. For example, the piezoelectric element 42 expands and contracts in the Y-axis direction by applying a drive voltage to the other electrode terminal while one electrode terminal is grounded.
The connection mode of the lead wire 72 to the piezoelectric element 42 will be described later.

The piezoelectric element 42 and the transmission shaft 44 are fixed to each other via an adhesive.
The method of connecting the piezoelectric element 42 and the transmission shaft 44 is arbitrary, and for example, the transmission shaft 44 and the piezoelectric element 42 may be connected by fitting them together.
Vibration generated in the piezoelectric element 42 is transmitted to the shaft holding portion 45 via the transmission shaft 44.

With such a configuration, the relative positions of the lens holder 31, the transmission shaft 44, and the piezoelectric element 42 are fixed, and the lens holder 31, the transmission shaft 44, and the piezoelectric element 42 can move relative to the shaft holding portion 45 that functions as a fixed-side member.
That is, the lens unit 30 can move along the y-axis (axis line that coincides with the optical axis of the lenses L1 to L3) according to the driving of the piezoelectric element 42, and the lenses L1 to L3 with respect to the imaging surface of the image sensor 12 By adjusting the arrangement height, the subject image can be formed on the imaging surface of the image sensor 12 as intended.

In the present embodiment, the piezoelectric element 42 is attached only to the transmission shaft 44. The piezoelectric element 42 and the transmission shaft 44 are not directly fixed to the shaft holding portion 45 and the lens holder 31 which are fixed members.
Since such a configuration is adopted, without considering resonance with the fixed side member (the shaft holding portion 45, the lens holder 31), only by taking into account the inherent resonance guided from the piezoelectric element 42 and the transmission shaft 44, The drive frequency for the piezoelectric element 42 can be set appropriately.
That is, it becomes possible to set the drive frequency regardless of the state of incorporation of the individual lens units 30. Then, resonance with the fixed side member (the shaft holding part 45 and the lens holder 31) does not become a problem, so that the drive frequency band can be set wide. For example, by setting from a high frequency to a low frequency, the movement amount of the lens unit 30 per cycle can be increased, or the lens unit 30 can be moved at a high speed by fine movement, so that advanced movement control can be performed.
Thereby, high-speed and high-precision movement control of the lens unit 30 can be realized.

The configuration of the camera module will be described in more detail.
The image sensor 12 is bump-mounted on the transparent substrate 13, and a plurality of solder bumps (not shown) are arranged between the transparent substrate 13 and the image sensor 12.
By forming solder bumps on the transparent substrate 13 and mounting the image sensor 12 thereon, the transparent substrate 13 and the image sensor 12 are laminated.
Note that a wiring pattern is formed in advance on the back surface of the transparent substrate 13.
In this way, the positions of the image sensor 12 and the transparent substrate 13 are fixed, and electrical connection between the two is ensured.
Note that the imaging surface (light receiving surface) of the image sensor 12 is disposed on the transparent substrate 13 side.

  The distance (separation distance) between the image sensor 12 and the transparent substrate 13 is determined by the size of the solder bump described above. By appropriately controlling the size of the solder bump, the image sensor 12 and the transparent substrate 13 can be accurately positioned. Further, since the positioning is performed by a plurality of solder bumps, the distance between the image sensor 12 and the transparent substrate 13 is averaged.

The transparent substrate 13 is bump-connected to the wiring substrate 10. That is, the transparent substrate 13 is fixed and electrically connected to the wiring substrate 10 via the solder bumps.
In this way, the image sensor 12 is electrically connected to the wiring substrate 10 via the transparent substrate 13.

A space is secured between the image sensor 12 and the wiring substrate 10 by the solder bumps between the transparent substrate 13 and the wiring substrate 10.
In other words, the solder bump between the transparent substrate 13 and the wiring substrate 10 functions as a spacer for forming a space between the image sensor 12 and the wiring substrate 10.

  The housing 20 has a partition wall 22 that separates the upper space and the lower space, and the partition wall 22 is formed with an opening OP1 for optically communicating the upper and lower spaces. The opening OP1 only needs to be an opening in the optical sense.

  A reinforcing plate 15 is disposed under the wiring board 10. The reinforcing plate 15 is made of a resin material such as polyimide. The reinforcing plate 15 is black. By disposing the reinforcing plate 15, it is possible to suitably suppress the entry of extraneous light into the camera module 150. In order to further suppress the adverse effects of extraneous light, the wiring board 10 is also preferably black.

The structure of the shaft holder will be described in more detail.
FIG. 6 is a cross-sectional view of the lens unit.
FIG. 7 is an exploded perspective view of the shaft holding portion.
FIG. 8 is a cross-sectional view of the shaft holding portion.

  The shaft holding portion 45 includes a main body portion 45h, a pressing plate (plate member) 45p, a spring (elastic body) 45q, and a pressing plate (plate member) 45r. In the direction away from the transmission shaft 44, the pressing plate 45p, the spring 45q, and the pressing plate 45r are arranged in this order.

The main body 45h is made of a resin molded with a mold.
As shown in FIG. 8, the main body 45h has a ring-shaped portion (shaft holding portion) 45h1 and a storage portion 45h2. The annular portion 45h1 is an annular portion having an opening through which the transmission shaft 44 is inserted and surrounding the transmission shaft 44 inserted through the opening. The storage part 45h2 is the remaining part connected to the annular part 45h1.

Projecting portions 45h3 and 45h4 projecting toward the transmission shaft 44 are formed on the inner side surface of the annular portion 45h1.
Each of the projecting portions 45h3 and 45h4 is formed by partially forming the inner surface of the annular portion 45h1 as a flat surface.
When the protrusions 45h3 and 45h4 are made of resin, abrasion powder may be generated due to friction with the transmission shaft 44. To avoid such problems, here, the main body is formed by molding a zinc alloy. Part 45h is manufactured.
In addition, you may employ | adopt not only a zinc alloy but an aluminum alloy and another metal material.

The transmission shaft 44 is abutted and held at three points by the presser plate 45p, the projecting part 45h3, and the projecting part 45h4 between the main body part 45h and the presser plate 45p.
Note that the three contact points are at substantially equal intervals and are sequentially shifted by 120 degrees.

A curved surface 45h2a corresponding to the outer peripheral surface of the lens holder 31 is formed in the main body 45h.
Accordingly, the lens holder 31 can be disposed closer to the housing 20 while ensuring the size of the main body 45h to some extent.
The main body 45h has a tail 45h2b extending in a direction away from the transmission shaft 44. Then, the main body 45 h is fixed to the housing 20 by fitting the tail portion 45 h 2 b and the housing 20.

The spring 45q is a general coil spring. The specific configuration of the spring 45q is arbitrary, and other types of elastic bodies (plate springs, resin rubber, etc.) may be used. The spring 45q biases the pressing plate 45p in a direction (direction along the axis Lx2) that forms 90 degrees with respect to the arrangement direction (direction along the axis Lx1) of the transmission shaft 44 as viewed from the lens holder 31.
Note that the angle formed by the axis Lx1 and the axis Lx2 is not limited to 90 degrees.
The angle formed by the axis Lx1 and the axis Lx2 may be selected in the range of 45 to 135 degrees.

As shown in FIG. 7, the presser plate 45p, the spring 45q, and the presser plate 45r are sequentially pushed into the space formed in the main body portion 45h, and the presser plate 45r is bonded and fixed to the main body portion 45h.
Thereby, the presser plate 45p, the spring 45q, and the presser plate 45r are positioned.

  The spring 45q is confined in the space of the main body 45h by the presser plate 45r, and urges the presser plate 45p toward the transmission shaft 44. The transmission shaft 44 is pressed by the pressing plate 45p and abuts against the protrusions 45h3 and 45h4. The transmission shaft 44 is sandwiched between the main body 45h and the pressing plate 45p. In other words, the transmission shaft 44 and the shaft holding portion 45 are in frictional engagement with each other.

  The presser plates 45p and 45r are made of, for example, a metal plate or a resin plate formed by press molding. For example, the holding plates 45p and 45r may be formed of a metal material such as a zinc alloy or an aluminum alloy. Thereby, even if there is sliding between the transmission shaft 44 and the presser plate 45p, it is possible to suppress the generation of wear powder from the presser plate 45p.

Next, as illustrated in FIG. 9, the shaft holding portion 45 is attached to the housing 20.
Projections 26 a and 26 b are formed on the inner side surface of the housing 20. The tail portion 45h2b described above is fitted between the protrusion 26a and the protrusion 26b. By fixing the shaft holding portion 45 to the housing 20 by fitting, the shaft holding portion 45 can be firmly fixed to the housing 20.
Note that the shaft holding part 45 may be fixed to the housing 20 using a normal adhesive.

  Although the side wall of the housing 20 is partially removed, the outer surface of the main body 45h is flush with the outer surface of the housing 20 by attaching the main body 45h to the housing 20.

  It should be noted that the shaft holding portion 45 and the housing 20 can be integrally molded by adopting insert molding.

  Furthermore, as shown in FIG. 9, a rail 24 for guiding the displacement of the lens unit 30 is formed in the housing 20. The rail 24 is received by the rail receiving portion 35 formed on the outer periphery of the lens holder 31, and the lens holder 31 is slidably brought into contact with the housing 20. As the piezoelectric element 42 is driven, the lens holder 31 is guided by the rail 24 and can be stably displaced.

In addition, as shown in FIG. 9, a metal plate (fixed wiring portion) 71 is attached to the housing 20.
The metal plate 71 is insert-molded in the housing 20 so that one end is inside the housing and the other end is outside the housing. Inside the housing, the piezoelectric element 42 is connected to the metal plate 71 with a lead wire 72.
This eliminates the need to pull out the lead wire 72 from the inside of the housing 20 to the outside, thereby reducing the time required for routing the lead wire 72 during manufacturing.
Further, by arranging the metal plate 71 at the corner adjacent to the corner where the piezoelectric element 42 is disposed, the length of the lead wire 72 can be effectively shortened.

Next, a system for operating the camera module 150 (configuration of the actuator drive unit) will be described.
FIG. 10 is a functional block diagram of the control system of the drive device.
The controller 80 applies a voltage to the piezoelectric element 42 via the drive voltage generation circuit 81.
The controller 80 activates the function of the camera module 150 in response to an operation by the operator.
At this time, the autofocus function of the camera module 150 is on, and the image sensor 12 is also in the imaging mode.
The drive voltage generation circuit 81 generates a drive voltage to be applied to the piezoelectric element 42 in response to a control signal from the controller 80.

  Here, the piezoelectric element (drive device) that displaces the lens holder 31 by the expansion / contraction operation generated in the piezoelectric element is configured by the piezoelectric element 42, the transmission shaft 44, the shaft holding unit 45, and the drive voltage generation circuit 81.

The drive voltage generation circuit 81 will be described.
FIG. 11 is a circuit diagram of the drive voltage generation circuit 81.
The drive voltage generation circuit 81 has four switch elements.
A node to which the drive voltage + E is supplied from the drive power supply is referred to as a node a. A first switch element Q1 and a third switch element Q3, which are P-channel MOSFETs, are connected to the node a.
Specifically, the source of the first switch element Q1 and the source of the third switch element Q3 are commonly connected to the node a.
Further, a fourth switch element Q4 is connected in series to the first switch element Q1, and a second switch element Q2 is connected in series to the third switch element Q3.
The fourth switch element Q4 is an N-channel MOSFET, and the drain of the fourth switch element Q4 is connected to the drain of the first switch element Q1.
The third switch element Q3 is an N-channel MOSFET, and the drain of the third switch element Q3 is connected to the drain of the second switch element Q2.
The source of the fourth switch element Q4 and the source of the second switch element Q2 are connected to the ground power supply via the common connection node b.

A connection node between the drain of the first switch element Q1 and the drain of the fourth switch element Q4 is defined as a node c (first output terminal).
This node c is connected to the first electrode of the piezoelectric element.
A connection node between the drain of the third switch element Q3 and the drain of the second switch element Q2 is a node d (second output terminal).
The node d is connected to the second electrode of the piezoelectric element 42.

Here, a wiring connecting the node c and the node d is a coupling line.
The drive voltage generation circuit 81 is a so-called H bridge circuit.

  Here, a path from the drain of the first switch element Q1 to the piezoelectric element 42 is defined as a first output stage. A first inductive element 91 is provided in the first output stage. More specifically, a first inductive element 91 is provided between the node c and the piezoelectric element 42. A path from the drain of the third switch element Q3 to the piezoelectric element 42 is a second output stage. A second inductive element 92 is provided in the second output stage. More specifically, a second inductive element 92 is provided between the node d and the piezoelectric element 42.

  The first inductive element 91 and the second inductive element 92 are, for example, coils. The inductances of the first inductive element 91 and the second inductive element 92 are equal.

  Further, the control signal applied from the controller 80 to the gate of the first switch element Q1 is Sc1, the control signal applied from the controller 80 to the gate of the second switch element Q2 is Sc2, and the control signal applied from the controller 80 to the gate of the third switch element Q3. The control signal to be applied is Sc3, and the control signal applied from the controller 80 to the gate of the fourth switch element Q4 is Sc4.

  In the drive voltage generation circuit 81 configured as described above, the first switch element Q1, the first inductive element 91, and the second switch element Q2 apply the drive voltage + E from one side of the piezoelectric element 42. 1 constitutes a drive circuit. Further, the third switch element Q3, the second inductive element 92, and the fourth switch element Q4 constitute a second drive circuit that applies the drive voltage + E from the other side of the piezoelectric element 42 (ie, from the reverse direction).

FIG. 12 is a timing chart showing an operation sequence of the drive voltage generation circuit 81.
In the period A, the drive control signal Sc3 and the drive control signal Sc2 are at a high level, and the drive control signal Sc1 and the drive control signal Sc4 are at a low level.
At this time, the first switch element Q1 and the second switch element Q2 are turned on, and the third switch element Q3 and the fourth switch element Q4 are turned off.
This state is shown in FIG.
On the other hand, in the period B, the drive control signal Sc1 and the drive control signal Sc4 are at a high level, and the drive control signal Sc3 and the drive control signal Sc2 are at a low level.
At this time, the third switch element Q3 and the fourth switch element Q4 are turned on, and the first switch element Q1 and the second switch element Q2 are turned off.
This state is shown in FIG.
Here, the period A is shorter than the period B.

The movement of the lens unit 30 will be described with reference to FIGS.
As shown in FIG. 15, the lens holder 31 is displaced in the forward direction as the voltage Vs across the piezoelectric element 42 changes positively or negatively.
In FIG. 15, the displacement of the lens holder 31 is indicated by an arrow. That is, the lens holder 31 is displaced between the times t1 and t2, and is not displaced between the times t2 and t3. The same applies to other periods.

This will be schematically described with reference to FIG.
As shown in FIG. 16, the expansion and contraction of the piezoelectric element 42 and the displacement of the lens holder 31 are associated with each other.
Between the times t1 and t2, the voltage Vs across the piezoelectric element 42 rises steeply.
In response to the rapid rise of the voltage, the piezoelectric element 42 expands rapidly.
When the piezoelectric element 42 changes rapidly, the transmission shaft 44 slides with respect to the shaft holding portion 45.
As a result, the lens holder 31 is also displaced together with the transmission shaft 44.

On the other hand, between the times t2 and t3, the voltage Vs across the piezoelectric element 42 falls slowly.
In response to the slow falling of the voltage, the piezoelectric element 42 contracts relatively slowly. At this time, the change of the piezoelectric element 42 does not generate a force for displacing the transmission shaft 44, and the transmission shaft 44 remains in place.
The lens holder 31 together with the transmission shaft 44 remains in place.

Thus, the lens holder 31 is displaced with respect to the shaft holding portion 45 when the piezoelectric element 42 expands rapidly. In other words, the lens holder 31 is not displaced with respect to the shaft holding portion 45 when the piezoelectric element 42 contracts slowly.
In this case, in order to displace the lens holder 31 efficiently, it can be said that the piezoelectric element 42 should be extended in a short time by narrowing the pulse width of the switching pulse SP.
Considering that it is necessary to ensure the discharge time of the current accumulated in the piezoelectric element 42, it can be said that the duty ratio of the switching signal should be set small.

In the present embodiment, the first inductive element 91 is provided in the first output stage (between the node c and the piezoelectric element 42), and the second inductive element is provided in the second output stage (between the node d and the piezoelectric element 42). Since the element 92 is provided, the second driving circuit (the first switch element Q1, the first inductive element 91, the second switch element Q2) also applies the drive voltage from one side of the piezoelectric element 42. Gain is obtained even when a drive voltage is applied from the other side of the piezoelectric element 42 (ie, from the opposite direction) in the drive circuit (the third switch element Q3, the second inductive element 92, the fourth switch element Q4), and is simulated. In addition, the drive signal level can be made higher than the power supply voltage level E.
The reason will be described next.

Since inductive elements 91 and 92 are provided in the first and second output stages in the present embodiment, the first drive circuit and the second drive circuit are each represented by an equivalent circuit shown in FIG.
In FIG. 17, R0 represents the on-resistance of the switch elements Q1-Q4.
The on-resistance of each switch element Q1-Q4 is generally 1 [Ω] or less, although it depends on the element characteristics.
L represents the inductance of the inductive element (91, 92).
Cp represents the capacitance value of the piezoelectric element 42.
This equivalent circuit is a configuration of a filter circuit having a peak at a resonance point, and constitutes a so-called secondary LPF (low-pass filter).
The LPF resonance point and fc (cutoff frequency) are determined by the resonance of L and Cp.
By selecting the drive frequency and L according to R0 and Cp, a gain of several dB can be obtained within the drive frequency band, and the drive signal level can be increased in a pseudo manner.

FIG. 18 shows simulation results when Ro = 0.1 (Ω), Cp = 30 (nF), and L = 6.8 (uH).
FIG. 18 shows the frequency range from 1 kHz to 10 MHz.
As shown in FIG. 18, the gain is zero until the drive frequency is around 100 kHz. However, when the drive frequency exceeds 100 kHz, the gain starts to increase, and the highest gain is obtained by resonance between 300 kHz and 400 kHz. When the resonance point is passed, the gain begins to decrease rapidly, reaches zero at around 500 kHz, and further decreases as the drive frequency increases.

The drive frequency band is preferably selected so that the gain is greater than zero.
In the example of FIG. 18, it is preferable to select a drive frequency between 100 kHz and 500 kHz as indicated by a section f1 in the figure.
As a result, even when the piezoelectric element 42 is downsized and the power supply voltage E is lowered, a pseudo high voltage can be applied to the piezoelectric element 42 to improve the displacement vibration characteristics of the piezoelectric actuator. be able to.
When the piezoelectric element becomes smaller and the capacitance value of the piezoelectric element becomes smaller, the operating capability can be improved even for small and low-voltage piezoelectric actuators by reselecting the inductance L value and drive frequency accordingly. Can be maintained.

Further, as the driving frequency, the gain is zero or more, but it is preferable to exclude the frequency before and after the frequency at the resonance point.
When driving frequencies before and after the resonance point are selected, the gain varies greatly if the frequency is slightly shifted. As a result, there is a risk that the variation in operating characteristics from product to product becomes very large. Accordingly, it is preferable to select the driving frequency to be selected from the sections f2 and f3 while avoiding the section f4 in FIG.
For example, the frequency range f4 to be avoided may be 10% before and after the resonance point frequency, or 30% before and after the resonance point frequency.

Further, it is preferable to select a driving frequency that is lower than the frequency of the resonance point and has a gain greater than zero.
FIG. 19 is a diagram in which a region in the middle of increasing the gain toward the resonance point peak in FIG. 18 is extracted.
In FIG. 19, the frequency range is 1 kHz to 300 kHz.
It is preferable to select the drive frequency in a region where the gain increases toward the resonance point peak, such as a region surrounded by a circle in FIG.
Even after the resonance point peak (for example, section f3 in FIG. 18), the gain is greater than zero, but since the decrease curve is steep, the gain changes greatly if the drive frequency deviates even slightly from the set value.
In this regard, if the gain is in the middle of the increase toward the resonance point peak (section f5 in FIG. 19), the curve is gentle, so that variation among products can be suppressed.
As shown in FIG. 19, when the driving frequency is 150 kHz, a gain of about 2 dB can be obtained.

FIG. 20 and FIG. 21 show the results of simulation by changing the inductance L of the inductive element.
In FIG. 20 and FIG. 21, a region where the gain is increasing toward the resonance point peak is circled, and the drive frequency is selected within the circle.
In FIG. 20, when the driving frequency is 150 kHz, a gain of about 3 dB is obtained.
In FIG. 21, when the drive frequency is 150 kHz, a gain of about 6 dB can be obtained.

By selecting the drive frequency as described above, a pseudo high voltage can be applied to the piezoelectric element 42, and the displacement vibration characteristics of the piezoelectric actuator can be improved.
Here, in the conventional piezoelectric actuator, since the piezoelectric element or the drive shaft is fixed to the fixed member, it is necessary to avoid resonance with the fixed member when selecting the drive frequency.
For this reason, the drive frequency band cannot be set wide, and the drive frequency can be selected only within a narrow range in which resonance with the fixed member can be reliably avoided.
In this respect, in the present embodiment, the piezoelectric element 42 and the transmission shaft 44 are not directly fixed to the shaft holding portion 45 and the lens holder 31 which are fixed side members, so that the fixed side member (the shaft holding portion 45, The driving frequency for the piezoelectric element 42 can be appropriately set only by considering the inherent resonance introduced from the piezoelectric element 42 and the transmission shaft 44 without considering the resonance with the lens holder 31).
Therefore, as described above, the drive frequency can be selected from the range where the gain can be obtained.

Further, as shown in FIG. 22, the harmonic component of the drive signal can be suppressed.
For example, it can be seen that suppression of about -10 dB is effective for the harmonic component of 400 kHz, and further higher harmonic components are further suppressed. That is, it can be seen that the high-frequency component mixed in the drive signal can be sufficiently suppressed.

For example, high-frequency noise may be mixed in the drive voltage via the power line.
FIG. 23 is an example of a drive voltage in which power line noise has been carried.
If such noise enters, the movement of the piezoelectric actuator stops intermittently, which causes a problem that the operation becomes unstable.
In this respect, the drive voltage generation circuit 81 of the present embodiment can suppress harmonic noise as shown in FIG. 24 by the filter effect, and can stabilize the operation of the piezoelectric actuator.

In addition, when actually incorporating a piezoelectric actuator into a product, as shown in FIG. 9, it must pass through the lead wire 72, the metal terminal 71, the wiring board 10, etc., so the wiring length of the output stage (node c, The wiring from d to the piezoelectric element 42 becomes longer.
In addition, the wiring length of the output stage varies depending on the product. Then, since the wiring inductance varies depending on the wiring length, there is a possibility that the operation may vary due to unexpected resonance.
In this regard, in this embodiment, the inductive elements 91 and 92 are provided in advance in the output stage, and the inductance of the inductive elements 91 and 92 is sufficiently larger than the wiring inductance. Therefore, even if the wiring length is different, it does not have an inductance exceeding the effect of the inductive elements 91 and 92, so there is no risk of variations in the operation of the piezoelectric actuator due to unexpected resonance, and operational stability is improved. Can do.

  In the first embodiment, both the voltage is applied by the first drive circuit and the voltage is applied by the second drive circuit, the two elements (the first dielectric element 91) must be interposed between the piezoelectric elements 42. The second dielectric element 92) is configured to work. As a result, the back electromotive force acts on both the positive side and the negative side, and an effect of amplifying the drive voltage both on the positive side and the negative side can be obtained, and a large amplification effect can be obtained efficiently.

(Modification 1)
As a modification of the above embodiment, an example in which the arrangement position of the inductive element is changed will be described.
First, the drive voltage generation circuit 811 shown in FIG.
Here, in FIG. 25, a connection node between the drain of the first switch element Q1 and the drain of the fourth switch element Q4 is defined as a node c. This node c is connected to the first electrode of the piezoelectric element.
A connection node between the drain of the third switch element Q3 and the drain of the second switch element Q2 is a node d. The node d is connected to the second electrode of the piezoelectric element 42.
At this time, in Modification 1, the first inductive element 911 is provided between the drain of the first switch element Q1 and the node c, and the second inductive element is provided between the drain of the third switch element Q3 and the node d. An element 921 is provided.
Also in this configuration, the first inductive element 911 is in the first output stage, and the second inductive element is in the second output stage.
Therefore, by the same operation as the drive voltage generation circuit 82 described in the first embodiment, the first drive circuit (first switch element Q1, first inductive element 91, second switch element Q2) Even when a drive voltage is applied from one side, the second drive circuit (the third switch element Q3, the second inductive element 92, the fourth switch element Q4) drives from the other side of the piezoelectric element 42 (that is, from the reverse direction). Even when a voltage is applied, a gain can be obtained, and the drive signal level can be made higher than the power supply voltage level E in a pseudo manner.

(Modification 2)
Next, Modification 2 will be described with reference to FIG.
Modification 2 is a modification that assumes the case where the drive voltage generation circuit 812 is configured as a single chip.
The second modification has a configuration in which a fifth switch element Q5 and a sixth switch element Q6 are further added to the drive voltage generation circuit 81 of FIG.
Here, the drain of the fifth switch element Q5 is connected to the first electrode of the piezoelectric element 42, and the source of the fifth switch element Q5 is connected to the ground power supply.
The drain of the sixth switch element is connected to the second electrode of the piezoelectric element 42, and the source of the sixth switch element Q6 is connected to the ground power source.
Further, the control signal Sc4 common to the fourth switch element Q4 is applied to the gate of the fifth switch element Q5, and the control signal Sc2 common to the second switch element Q2 is applied to the gate of the sixth switch element Q6. Has been.
That is, the fifth switch element Q5 and the fourth switch element Q4 perform the same operation, and the sixth switch element Q6 and the second switch element Q2 perform the same operation.

In this configuration, when the control signals Sc1-Sc4 are sent in the timing chart shown in FIG. 12, the main operation is the same as that of the drive voltage generation circuit 82, and the same effect is obtained.
Here, in the drive voltage generation circuit 82 of FIG. 11, the drive voltage is applied from one side of the piezoelectric element 42 in the first drive circuit (first switch element Q1, first inductive element 91, second switch element Q2). In this case, the GND potential is applied to the piezoelectric element 42 via the second switch element Q2, but in Modification 2, the GND potential is applied to the piezoelectric element via the sixth switch element Q6 that operates in the same manner as the second switch element Q2. (See Figure 27).
In this case, the second inductive element 92 is not included in the current path, but the action described above is sufficiently obtained by including the first inductive element 91 on the voltage application side, and the pseudo Thus, the drive signal level can be increased.

Similarly, in the drive voltage generation circuit 82 of FIG. 11, the second drive circuit (the third switch element Q3, the second inductive element 92, the fourth switch element Q4) is from the other side of the piezoelectric element 42 (ie, from the reverse direction). ) When applying drive voltage, the GND potential was applied to the piezoelectric element 42 via the fourth switch element Q4. However, in the second modification, via the fifth switch element Q5 that performs the same operation as the fourth switch element Q4. Thus, a GND potential is applied to the piezoelectric element 42 (FIG. 28).
In this case, the first inductive element 91 is not included in the current path, but the action described above is sufficiently obtained by including the second inductive element 92 on the voltage application side, and the pseudo Thus, the drive signal level can be increased.

(Modification 3)
In the first embodiment, the piezoelectric element 42 is attached to the drive shaft 44, and the vibration of the piezoelectric element is transmitted to the drive shaft, so that the drive shaft, the piezoelectric element, and the lens holder 31 are integrated with the shaft holding portion 45. The configuration of sliding is explained as an example.
On the other hand, as shown in FIG. 29, the piezoelectric element 430 may be directly attached to the slider 420.
That is, in FIG. 29, the slider 420 is slidably engaged with the support shaft 440. Specifically, the slider 42 is provided with a through hole 421, and the support shaft 44 is inserted into the through hole 421. A lens holder 70 is attached to the slider 42 and integrated.
The lens holder 70 is guided by guide rails 50 and 51.

Further, the piezoelectric element 430 is attached to the slider 420. The piezoelectric element 430 is attached to an end surface 423 that is perpendicular to the moving direction of the surface of the slider 420.
At this time, the piezoelectric element 430 is attached to the slider 420 so that the expansion / contraction direction of the piezoelectric element 430 and the moving direction of the slider 420 are parallel to each other.

In such a configuration, when the piezoelectric element expands and contracts, the slider 420 moves relative to the support shaft due to the vibration.
At this time, the piezoelectric element 430 as a driving source is fixed to the slider 420 as a moving body. As described above, since the drive source is attached to the moving object, the power obtained from the piezoelectric element 430 can be effectively converted into the displacement of the slider 420.
Therefore, energy consumption can be reduced and control accuracy can be increased.
Further, the piezoelectric element 430 is not directly fixed to the support shaft 440 which is a fixed side member. Since such a configuration is adopted, the driving frequency for the piezoelectric element 430 is appropriately set only by considering the inherent resonance guided from the piezoelectric element 430 and the slider 420 without considering the resonance with the fixed-side member. be able to. That is, since resonance with the fixed member does not become a problem, a wide driving frequency band can be set.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

10 ... Wiring board, 11 ... Connector, 12 ... Image sensor, 13 ... Transparent board, 15 ... Reinforcement plate, 20 ... Housing, 22 ... Bulkhead, 24 ... Rail, 26a ... Projection, 26b ... Projection, 30 ... Lens unit , 31 ... Lens holder, 32 ... Connection part, 32a ... Support plate, 32b ... Support plate, 35 ... Rail receiving part, 42 ... Piezoelectric element, 44 ... Transmission shaft, 45 ... Shaft holding part, 45h ... Main body of shaft holding part 45h1 ... Ring-shaped part 45h2 ... Storage part 45h2a ... Curved surface 45h2b ... Tail part 45h3 ... Projection part 45h4 Projection part 45p ... Presser plate 45r ... Presser plate 50 ... Lid 71 ... Metal terminal 72 ... Lead wire, 80 ... Controller, 81, 811, 812 ... Drive voltage generation circuit, 91 ... First inductive element, 92 ... Second inductive element, 100 ... Piezoelectric actuator, 101 ... Piezoelectric element, 102 ... Driving member , 103 ... engaging member, 104 ... drive circuit, 104a ... control circuit, 120 ... support member, 146 ... inductive element, 150 ... camera module, L ... lens, Q1-Q4 ... switch element , Q5-Q6 ... switching device, Sc1-Sc4 ... driving control signal.

Claims (11)

A fixed side member;
A lens holder movably engaged with the fixed side member;
A piezoelectric element that is fixed in position relative to the lens holder and expands and contracts in response to application of a driving voltage;
A drive shaft that is fixed with respect to the lens holder and that receives vibrations generated by the piezoelectric element;
A drive voltage generation circuit for generating a drive voltage to be applied to the piezoelectric element;
Equipped with a,
The lens holder is engaged with the fixed member through frictional engagement between the fixed member and the drive shaft,
The lens holder, the piezoelectric element, and the drive shaft move substantially during a period in which the piezoelectric element is stretched or contracted relatively steeply .
The drive voltage generation circuit includes:
A first dielectric element provided on one electrode side of the piezoelectric element;
A second dielectric element provided on the other electrode side of the piezoelectric element;
A first drive circuit that applies a positive drive voltage before Symbol piezoelectric element,
And a second driving circuit for applying a negative drive voltage before Symbol piezoelectric element,
By generating an alternating drive voltage for expanding and contracting the piezoelectric element by switching between the first drive circuit and the second drive circuit ,
The first drive circuit supplies current to the piezoelectric element from one of the first and second inductive elements from a high potential side,
It said second driving circuit current supplied to the piezoelectric element from the high potential side through the other of said first and second inductive elements, the driving device. The drive voltage generation circuit is an H bridge circuit, and has a coupling line that connects between the first output terminal and the second output terminal of the H bridge circuit,
2. The driving device according to claim 1, wherein the piezoelectric element is disposed in the middle of the coupling line, and the coupling line is provided with two dielectric elements with the piezoelectric element interposed therebetween. . Frequency before Symbol driving voltage, the switch resistance included in the first and second drive circuit, the capacitance of the piezoelectric element, and the inductance of the inductive element, the frequency range in which the gain is greater than zero dB by the interaction of The drive device according to claim 1, wherein the drive device is selected from the following. The frequency of the drive voltage is selected from a frequency range in which the gain is greater than 2 dB due to the interaction of the switch resistance included in the first and second drive circuits, the capacitance of the piezoelectric element, and the inductance of the inductive element. The drive device according to any one of claims 1 to 3 , wherein The frequency of the driving voltage is a frequency range in which the gain is greater than zero by the interaction of the switch resistance included in the first and second driving circuits, the capacitance of the piezoelectric element, and the inductance of the inductive element, and driving device according to any one of claims 1 to 4 around 10%, characterized in that it is selected from the frequency range excluding the frequency of the resonance point. The frequency of the driving voltage is a frequency range in which the gain is greater than zero by the interaction of the switch resistance included in the first and second driving circuits, the capacitance of the piezoelectric element, and the inductance of the inductive element, 6. The driving device according to claim 1 , wherein the driving device is selected from a frequency range smaller than the frequency of the resonance point. The drive according to any one of claims 1 to 6, wherein the piezoelectric element is fixed to the drive shaft and fixed to the lens holder via the drive shaft. apparatus. The driving device according to any one of claims 1 to 7, wherein the piezoelectric element is driven in a manner that the piezoelectric element does not contact the fixed side member and the lens holder. Before SL piezoelectric element is fixed to one end of said drive shaft,
The drive device according to any one of claims 1 to 8 , wherein the drive shaft is slidably held in an axial direction by a shaft holding portion as the fixed side member. A driving device according to any one of claims 1 to 9 ,
An image acquisition apparatus comprising: an imaging unit that acquires an image input through a lens held by the lens holder . An electronic apparatus comprising the image acquisition device according to claim 10 .

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