JP2009089582A - Drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive device which can be made into a low-profile structure, in a direction which is substantially perpendicular to the direction of expansion and contraction of an electromechanical transducer. <P>SOLUTION: In the drive device 1, a piezoelectric element 5 is fixed on the front surface of a FPC 7, in such a manner that the expansion and contraction direction of the piezoelectric element 5 is substantially parallel to the front surface of the FPC 7, and the piezoelectric element 5 is electrically connected to the FPC 7. According to this configuration, the thickness direction of the FPC 7 conforms to a direction that is substantially perpendicular to the expansion and contraction direction of the piezoelectric element 5, which makes the drive device 1 into a low-profile structure in this direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a driving device suitable for driving a lens or the like in, for example, a mobile phone with a camera or a small digital camera.

  As a conventional driving device in the technical field, Patent Documents 1 and 2 include an electromechanical conversion element that expands and contracts along a predetermined expansion and contraction direction, a drive member attached to one end of the electromechanical conversion element in the expansion and contraction direction, There is described what includes a driven body frictionally engaged with a driving member and a printed circuit board such as a flexible printed circuit board in which an electromechanical conversion element is electrically connected by solder, conductive adhesive, or the like.

  Patent Document 3 discloses an electromechanical conversion element that expands and contracts along a predetermined expansion / contraction direction, a drive member attached to one end of the electromechanical conversion element in the expansion / contraction direction, and a driven object that is frictionally engaged with the drive member. What comprises a body and a support that supports an electromechanical transducer is described.

In these drive devices, a drive pulse having a sawtooth waveform is applied to the electromechanical conversion element, and the electromechanical conversion element is deformed in a state where the expansion speed and the contraction speed are different. When the electromechanical transducer is deformed at a low speed, the driven body is stationary with respect to the driving member due to friction. Conversely, when the electromechanical transducer is deformed at a high speed, the driven body is transformed into the driving member by inertia. Move against. Therefore, by repeatedly applying a drive pulse having a sawtooth waveform to the electromechanical transducer, the driven body can be intermittently moved at a fine pitch.
JP 2007-274777 A JP 2006-31794 A JP 2007-74889 A

  However, in the driving devices described in Patent Documents 1 and 2, since the electromechanical conversion element is attached to the printed circuit board so that the expansion and contraction direction of the electromechanical conversion element is substantially perpendicular to the surface of the printed circuit board, the electromechanical conversion is performed. There is a problem that a reduction in the height of the driving device in a direction substantially perpendicular to the expansion / contraction direction of the element is hindered.

  Such a problem is also common in the drive device described in Patent Document 3, in which an electrical signal for driving the electromechanical transducer is transmitted by electrically connecting a lead wire to the electromechanical transducer. Therefore, it is the same.

  In the drive device described in Patent Document 3, it is common to transmit an electrical signal for driving the electromechanical transducer by electrically connecting a lead wire to the electromechanical transducer. For this reason, the following problems may occur. That is, when assembling the drive device, the lead wire is formed after the electromechanical conversion element is fixed to the support, so that stress concentrates on the connection between the electromechanical conversion element and the lead wire. As a result, there is a possibility that the electrical signal cannot be reliably transmitted to the electromechanical transducer.

  Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide a drive device that can achieve a low profile in a direction substantially perpendicular to the expansion / contraction direction of the electromechanical transducer. .

  In order to achieve the above object, a drive device according to the present invention includes an electromechanical conversion element that expands and contracts along a predetermined expansion / contraction direction, a drive member attached to one end of the electromechanical conversion element in the expansion / contraction direction, and a drive member And a printed circuit board that transmits an electric signal for driving the electromechanical conversion element, and the electromechanical conversion element has an expansion / contraction direction substantially parallel to the surface of the printed circuit board. Thus, it is attached to the surface of the printed circuit board and is electrically connected to the printed circuit board.

  In this drive device, the electromechanical transducer is attached to the surface of the printed circuit board so that the expansion / contraction direction of the electromechanical transducer is substantially parallel to the surface of the printed circuit board, and the electromechanical transducer is electrically connected to the printed circuit board. ing. As a result, the thickness direction of the printed circuit board coincides with the direction substantially perpendicular to the expansion / contraction direction of the electromechanical conversion element, so that the height of the drive device can be reduced in this direction.

  Further, in the drive device according to the present invention, the length of the printed circuit board in the expansion / contraction direction is equal to the length of the electromechanical conversion element in the expansion / contraction direction or the electric force in the expansion / contraction direction in the portion where the electromechanical conversion element is attached. The length is preferably shorter than the length of the mechanical conversion element. In this case, it is possible to prevent the printed board from obstructing the attachment of the driving member to one end of the electromechanical conversion element and the attachment of, for example, a weight to the other end of the electromechanical conversion element.

  In the drive device according to the present invention, the printed circuit board is preferably a flexible printed circuit board. By using a flexible printed circuit board as the printed circuit board, the degree of freedom of wiring layout can be increased.

  In the drive device according to the present invention, it is preferable that the electromechanical conversion element is electrically connected to the printed circuit board by a conductive adhesive. By using a conductive adhesive having lower rigidity and higher elasticity than solder, it is possible to prevent the expansion and contraction of the electromechanical conversion element from being hindered due to the electrical connection with the printed circuit board.

  In the drive device according to the present invention, it is preferable that the electromechanical conversion element is supported by an elastic member from the side with respect to the expansion / contraction direction at a portion facing the portion to which the printed board is attached. According to this configuration, since vibration due to expansion and contraction of the electromechanical conversion element is difficult to be transmitted to the elastic member, the driven body is securely attached to the drive member while preventing the influence of resonance due to expansion and contraction of the electromechanical conversion element. Can be moved.

  The drive device according to the present invention is frictionally engaged with the drive member, an electromechanical conversion element that expands and contracts along a predetermined expansion / contraction direction, a drive member attached to one end of the electromechanical conversion element in the expansion / contraction direction, and A driven body, a printed circuit board in which the electromechanical conversion element is electrically connected by a conductive adhesive, and transmits an electric signal for driving the electromechanical conversion element; and a support that supports the electromechanical conversion element; The support body supports the electromechanical conversion element by fixing the printed circuit board to the support body.

  In this driving apparatus, a printed circuit board in which electromechanical conversion elements are electrically connected by a conductive adhesive is used for transmission of electric signals for driving the electromechanical conversion elements. Therefore, the thickness direction of the printed circuit board can be made to coincide with the direction substantially perpendicular to the expansion / contraction direction of the electromechanical conversion element, and the height of the drive device can be reduced in this direction. Further, the printed circuit board is fixed to the support, so that the support supports the electromechanical conversion element. This avoids stress concentration at the connection between the electromechanical transducer and the printed circuit board during assembly of the drive device, and reliably transmits electrical signals to the electromechanical transducer via the printed circuit board. Can do.

  In the drive device according to the present invention, the printed board is a flexible printed board, and is preferably fixed to the support via a reinforcing member. By using a flexible printed circuit board as the printed circuit board, the degree of freedom in wiring layout can be increased. In addition, since the flexible printed circuit board is fixed to the support through the reinforcing member, it is possible to prevent the flexible printed circuit board from being deformed and damaging the connecting portion between the electromechanical transducer and the flexible printed circuit board.

  According to the present invention, it is possible to reduce the height of the drive device in a direction substantially perpendicular to the expansion / contraction direction of the electromechanical transducer.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.
[First Embodiment]

  FIG. 1 is a cross-sectional view of a first embodiment of a drive device according to the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1 and 2, the driving device 1 is a device for driving the lens 3 held by the lens frame (driven body) 2 along the optical axis OA. It is suitable for a small digital camera or the like. The drive device 1 includes a piezoelectric element (electromechanical conversion element) 5, a drive shaft (drive member) 6, a flexible printed circuit board (FPC) 7, and a weight 11 in a holder 4 that constitutes the outer periphery of the drive device 1. Yes.

  The piezoelectric element 5 expands and contracts along a stretching direction (hereinafter simply referred to as “stretching direction”) parallel to the optical axis OA. A portion 5 b facing the portion 5 a to which the FPC 7 is attached in the piezoelectric element 5 is sandwiched by an elastic member 12 made of, for example, silicone, and the elastic member 12 is fixed to the holder 4. Thereby, the piezoelectric element 5 is elastically supported by the elastic member 12 from the side with respect to the expansion / contraction direction in the portion 5b facing the portion 5a to which the FPC 7 is attached. The drive shaft 6 extends along the expansion / contraction direction, and is fixed to one end of the piezoelectric element 5 in the expansion / contraction direction by an adhesive. The drive shaft 6 is formed in a columnar shape from a graphite complex in which graphite crystals are firmly combined, such as carbon graphite.

  The weight 11 is attached to the other end of the piezoelectric element 5 in the expansion / contraction direction. The weight 11 applies a load to the other end side of the piezoelectric element 5 to prevent the other end side of the piezoelectric element 5 from being displaced more than the one end side. The weight 11 is preferably heavier than the drive shaft 6 in order to efficiently transmit the expansion and contraction of the piezoelectric element 5 to the drive shaft 6 side. For example, if the piezoelectric element 5 is supported by fixing the other end side of the weight 11 to the holder 4, the elastic member 12 becomes unnecessary.

  One end portion of the drive shaft 6 passes through a bearing hole 41a formed in the partition portion 41 of the holder 4 with a clearance fit. On the other hand, the other end portion of the drive shaft 6 penetrates through a bearing hole 42a formed in the partition portion 42 of the holder 4 with a clearance fit. Thereby, the drive shaft 6 can reciprocate along the expansion and contraction direction. The holder 4 is formed with an opening 4a, and the opening 4a is covered with a detachable holder cover 13.

  The drive shaft 6 is frictionally engaged with the engagement portion 21 of the lens frame 2 whose movement region is restricted between the partition portions 41 and 42. FIG. 3 is a cross-sectional view taken along line III-III in FIG. As shown in FIG. 3, the plate member 22 is attached to the plate member 22 side by a plate member 22 having a V-shaped cross section fixed in the V groove 21 a of the engagement portion 21 and a plate spring 23 locked to the engagement portion 21. A plate member 24 having a V-shaped cross section that is biased sandwiches the drive shaft 6. Thereby, the engaging part 21 produces a fixed friction force between the drive shaft 6 in the movement.

  FIG. 4 is a perspective view of the periphery of the piezoelectric element of the drive device of FIG. As shown in FIG. 4, the piezoelectric element 5 is electrically connected to a tape-like FPC 7 extending in a direction substantially perpendicular to the expansion / contraction direction. The FPC 7 is electrically connected to a drive circuit (not shown), and transmits an electrical signal for driving the piezoelectric element 5 from the drive circuit to the piezoelectric element 5.

  The piezoelectric element 5 is fixed to the surface 7a of the FPC 7 by the conductive adhesive 8 so that the expansion / contraction direction is substantially parallel to the surface 7a of the FPC 7. The conductive adhesive 8 electrically connects the terminal of the piezoelectric element 5 and the wiring 17 provided on the surface 7a of the FPC 7. As the conductive adhesive 8, for example, a thermosetting adhesive containing 70% by weight of silver particles and 20% by weight of an epoxy resin is used.

  In the driving apparatus 1 configured as described above, an electric signal for driving the piezoelectric element 5 is transmitted from the driving circuit to the piezoelectric element 5 by the FPC 7, and the piezoelectric element 5 repeatedly expands and contracts by the input of the electric signal. . The drive shaft 6 reciprocates in accordance with the expansion and contraction. At this time, the speed at which the drive shaft 6 moves in one direction is different from the speed at which it moves in the other direction by making the extension speed and contraction speed of the piezoelectric element 5 different. Thereby, the engaging part 21 and the lens frame 2 are moved to a desired direction.

  As described above, in the driving device 1, the piezoelectric element 5 is fixed to the surface 7 a of the FPC 7 so that the expansion / contraction direction of the piezoelectric element 5 is substantially parallel to the surface 7 a of the FPC 7, and the piezoelectric element 5 is electrically connected to the FPC 7. It is connected to the. Thus, the thickness direction of the FPC 7 (direction substantially perpendicular to the surface 7a) matches the direction substantially perpendicular to the expansion / contraction direction of the piezoelectric element 5 (here, the direction substantially perpendicular to the extending direction of the FPC 7). The drive device 1 can be reduced in height in this direction.

  In addition, since the FPC 7 is used to transmit an electrical signal for driving the piezoelectric element 5, the degree of freedom in wiring layout can be increased. Further, since the conductive adhesive 8 having lower rigidity and higher elasticity than solder is used for the electrical connection between the piezoelectric element 5 and the FPC 7, the piezoelectric element originates from the electrical connection with the FPC 7. It is possible to prevent the expansion and contraction of 5 from being inhibited.

Further, since the piezoelectric element 5 is supported by the elastic member 12 from the side in the expansion / contraction direction at the portion 5b facing the portion 5a to which the FPC 7 is attached, vibration due to expansion / contraction of the piezoelectric element 5 is elastic member 12. It becomes difficult to be transmitted to. As a result, it is possible to reliably move the lens frame 2 with respect to the drive shaft 6 while preventing the influence of resonance accompanying expansion and contraction of the piezoelectric element 5.
[Second Embodiment]

  FIG. 5 is a cross-sectional view of a second embodiment of the driving apparatus according to the present invention. 6 is a cross-sectional view taken along line VI-VI in FIG. 5, and FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. As shown in FIGS. 5 to 7, the driving device 1 is a device for driving the lens 3 held by the lens frame (driven body) 2 along the optical axis OA. It is suitable for a small digital camera or the like.

  The drive device 1 includes a holder (support) 4 that accommodates the lens frame 2. The holder 4 supports a piezoelectric element (electromechanical conversion element) 5 that expands and contracts along an expansion / contraction direction (hereinafter simply referred to as “extension / contraction direction”) parallel to the optical axis OA. A drive shaft (drive member) 6 is fixed to one end of the piezoelectric element 5 in the expansion / contraction direction with an adhesive so as to extend along the expansion / contraction direction. The drive shaft 6 is formed in a columnar shape from a graphite complex in which graphite crystals are firmly combined, such as carbon graphite. The holder 4 is formed with an opening 4a, and the opening 4a is covered with a detachable holder cover 13.

  One end portion of the drive shaft 6 passes through a bearing hole 41a formed in the partition portion 41 of the holder 4 with a clearance fit. On the other hand, the other end portion of the drive shaft 6 passes through a bearing hole 42a formed in the partition portion 42 of the holder 4 with a clearance fit. Thereby, the drive shaft 6 can reciprocate along the expansion and contraction direction.

  The drive shaft 6 is frictionally engaged with the engagement portion 21 of the lens frame 2 whose movement region is restricted between the partition portions 41 and 42. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. As shown in FIG. 8, the plate member 22 includes a plate member 22 having a V-shaped cross section fixed in a V groove 21 a formed in the engagement portion 21 and a plate spring 23 locked to the engagement portion 21. A plate member 24 having a V-shaped cross section biased to the side sandwiches the drive shaft 6. Thereby, the engaging part 21 produces a fixed friction force between the drive shaft 6 in the movement.

  Here, the support structure of the piezoelectric element 5 by the holder 4 will be described.

  9 is a perspective view of the periphery of the piezoelectric element of the drive device of FIG. 5, and FIG. 10 is a front view of the periphery of the piezoelectric element of the drive device of FIG. As shown in FIGS. 9 and 11, the piezoelectric element 5 is electrically connected to the surface of a tape-like flexible printed circuit board (FPC) 7 extending in a direction substantially perpendicular to the expansion / contraction direction by a conductive adhesive 8. ing. The conductive adhesive 8 is preferably elastic in order to improve impact resistance.

  The FPC 7 is electrically connected to a drive circuit (not shown) on the tip side, and transmits an electrical signal for driving the piezoelectric element 5 from the drive circuit to the piezoelectric element 5. A rectangular plate-like reinforcing plate (reinforcing member) 9 made of, for example, metal or polyimide is fixed to the back surface of the base end portion of the FPC 7 with an adhesive. The reinforcing plate 9 has an outer shape including a connection portion (that is, a portion where the conductive adhesive 8 is disposed) between the piezoelectric element 5 and the FPC 7 when viewed from a direction substantially orthogonal to the surface of the FPC 7. These piezoelectric element 5, drive shaft 6, FPC 7, conductive adhesive 8 and reinforcing plate 9 constitute a piezoelectric element unit 10.

  The piezoelectric element unit 10 is fixed to the shelf 43 of the holder 4 with bolts 19 via an elastic member 18 made of, for example, silicone. That is, the FPC 7 is fixed to the holder 4 via the reinforcing plate 9. Thus, the holder 4 supports the piezoelectric element 5 by fixing the FPC 7 to the holder 4 through the reinforcing plate 9. As shown in FIG. 6, each of the FPC 7 and the reinforcing plate 9 is formed so that a through hole 7 a and a through hole 9 a having an inner diameter larger than the outer diameter of the screw portion of the bolt 19 are continuous, The screw portion of the bolt 19 is screwed into the screw hole 43 a formed in the shelf portion 43 of the holder 4 through the through holes 7 a and 9 a and the through hole 18 a formed in the elastic member 18.

  As described above, in the driving device 1, the FPC 7 in which the piezoelectric element 5 is electrically connected by the conductive adhesive 8 is used for transmission of an electrical signal for driving the piezoelectric element 5. Therefore, it is possible to make the thickness direction of the FPC 7 coincide with the direction substantially perpendicular to the expansion / contraction direction of the piezoelectric element 5 and to reduce the height of the driving device 1 in this direction. Further, the FPC 7 is fixed to the holder 4 via the reinforcing plate 9 so that the holder 4 supports the piezoelectric element 5. As a result, when the drive device 1 is assembled, after the FPC 7 is fixed to the holder 4 via the reinforcing plate 9, the FPC 7 is formed so that the FPC 7 is electrically connected to the drive circuit at the tip side. However, since the piezoelectric element 5 is not directly fixed to the holder 4, stress concentration on the connection portion between the piezoelectric element 5 and the FPC 7 is avoided. Therefore, according to the driving device 1, an electric signal can be reliably transmitted to the piezoelectric element 5 through the FPC 7.

  In the driving device 1, the FPC 7 is used for transmission of an electrical signal for driving the piezoelectric element 5. Thereby, the freedom degree of the wiring layout for electrically connecting FPC7 to a drive circuit in the front end side can be enlarged. Moreover, the FPC 7 is fixed to the holder 4 via a reinforcing plate 9 having an outer shape including a connection portion between the piezoelectric element 5 and the FPC 7 when viewed from a direction substantially orthogonal to the surface of the FPC 7. Therefore, it is possible to prevent the FPC 7 from being deformed and damaging the connecting portion between the piezoelectric element 5 and the FPC 7 when the piezoelectric element unit 10 is loaded into the holder 4 during assembly of the driving device 1.

  In the driving device 1, the piezoelectric element unit 10 is fixed to the holder 4 with bolts 19. Thereby, for example, when the piezoelectric element 5 fails, the holder cover 13 can be removed from the holder 4 and the piezoelectric element unit 10 can be easily replaced through the opening 4 a of the holder 4.

  Further, in the driving device 1, a through hole 7 a and a through hole 9 a having an inner diameter larger than the outer diameter of the screw portion of the bolt 19 are formed continuously on the FPC 7 and the reinforcing plate 9. Further, the piezoelectric element unit 10 is fixed to the holder 4 via an elastic member 18. Accordingly, for example, even if the mounting angle of the drive shaft 6 varies in the piezoelectric element unit 10, when the piezoelectric element unit 10 is fixed to the holder 4 with the bolts 19, the bearing holes 41 a of the partition portion 41 and the bearings of the partition portion 42. It is possible to prevent the drive shaft 6 from being over-constrained by the hole 42a.

  Next, the operation of the drive device 1 will be described. FIG. 11 is a circuit diagram of a drive circuit that operates the piezoelectric element of the drive device of FIG. 12 is a waveform diagram of an input signal input to the drive circuit of FIG. 11, and FIG. 13 is a waveform diagram of an output signal output from the drive circuit of FIG.

  As shown in FIG. 11, the drive circuit 31 is provided in the control unit 30. The control unit 30 performs overall control of the driving device 1 and includes, for example, a CPU, a ROM, a RAM, an input signal circuit, an output signal circuit, and the like. The drive circuit 31 functions as a drive circuit for the piezoelectric element 5 and outputs an electrical signal for driving to the piezoelectric element 5. The drive circuit 31 receives a control signal from the control signal generation unit of the control unit 30, and outputs a drive electrical signal for the piezoelectric element 5 by voltage amplification or current amplification of the control signal. As the drive circuit 31, for example, an input stage configured by logic circuits U1 to U3 and an output stage including field effect transistors (FETs) Q1 and Q2 is used. The transistors Q1 and Q2 can output Hi output (high potential output), Lo output (low potential output), and OFF output (open output) as output signals.

  FIG. 12A shows an input signal that is input when the lens frame 2 is moved so that the engaging portion 21 approaches the piezoelectric element 5, and FIG. 5 is an input signal that is input when the lens frame 2 is moved away from the lens frame 2. 13A is an output signal that is output when the lens frame 2 is moved so that the engaging portion 21 approaches the piezoelectric element 5, and FIG. This is an output signal that is output when the lens frame 2 is moved away from the piezoelectric element 5.

  The output signals in FIGS. 13A and 13B are pulse signals that are turned ON / OFF at the same timing as the input signals in FIGS. 12A and 12B. The two signals in FIGS. 13A and 13B are input to the piezoelectric element 5 via the FPC 7. Although a pulse signal having a sawtooth waveform may be input to the piezoelectric element 5, as shown in FIG. 13, the piezoelectric element 5 is operated even when a pulse signal having a rectangular waveform is input. be able to. In this case, since the drive signal for the piezoelectric element 5 may be a pulse signal having a rectangular waveform, signal generation is facilitated.

  The output signals in FIGS. 13A and 13B are composed of two pulse signals having the same frequency. These two pulse signals have different phases, so that the potential difference between the signals increases stepwise and decreases rapidly, or the potential difference between the signals increases rapidly and decreases stepwise. It becomes the signal which becomes. By inputting these two signals, the expansion speed and contraction speed of the piezoelectric element 5 can be made different, and the engaging portion 21 and thus the lens frame 2 can be moved.

For example, in FIGS. 13A and 13B, after one signal changes from Hi (high) to Lo (low), the other signal is set to Hi. These signals are set so that when one signal becomes Lo, the other signal becomes Hi after a certain time lag t _OFF has elapsed. When both signals are Lo, the output is turned off (open state).

  As the output signals shown in FIGS. 13A and 13B, that is, electric signals for operating the piezoelectric element 5, signals having frequencies exceeding the audible frequency are used. In FIGS. 13A and 13B, the frequency of the two signals is a frequency signal exceeding the audible frequency, for example, a frequency signal of 30 to 80 kHz, more preferably 40 to 60 kHz. By using a signal having such a frequency, it is possible to reduce the operating sound in the audible region of the piezoelectric element 5.

  As described above, the driving device 1 operates as follows. That is, an electric signal is input to the piezoelectric element 5, and the piezoelectric element 5 repeats expansion and contraction by the input of the electric signal. The drive shaft 6 reciprocates in accordance with the expansion and contraction. At this time, the speed at which the drive shaft 6 moves in one direction is different from the speed at which it moves in the other direction by making the extension speed and contraction speed of the piezoelectric element 5 different. Thereby, the engaging part 21 and the lens frame 2 are moved to a desired direction.

  The present invention is not limited to the embodiment described above.

  For example, in the first embodiment, a so-called rigid substrate may be used in place of the FPC 7 for transmission of an electrical signal for driving the piezoelectric element 5. Solder may be used for electrical connection between the piezoelectric element 5 and the FPC 7 or rigid substrate.

  Moreover, although the said 1st Embodiment was the case where the drive device 1 drives the lens frame 2, the drive device may drive to-be-driven bodies other than the lens frame 2. FIG.

  In the second embodiment, as shown in FIG. 14, for example, an elastic member 14 made of silicone is interposed between the piezoelectric element 5 and the FPC 7, and the piezoelectric element 5 is attached to the surface of the FPC 7 with a conductive adhesive. 8 may be electrically connected. In this case, resonance with other components can be prevented and the vibration of the piezoelectric element 5 can be reliably transmitted to the drive shaft 6.

  In the second embodiment, the fixing of the piezoelectric element unit 10 to the holder 4 is not limited to the fixing by the bolt 19 but may be fixing by an adhesive. As an example, as shown in FIG. 15, in a state where the reinforcing plate 9 of the piezoelectric element unit 10 is in contact with the inner surface of the wall portion of the holder 4, the plurality of through holes 4 b formed in the wall portion of the holder 4 are inserted. The piezoelectric element unit 10 may be fixed to the holder 4 by filling the adhesive 15.

  Moreover, although the said 2nd Embodiment was a case where a printed circuit board is FPC7, what is called a rigid board | substrate may be sufficient as a printed circuit board. When the printed board is a rigid board, the reinforcing plate 9 is not essential.

  Moreover, although the said 2nd Embodiment was the case where the drive device 1 drives the lens frame 2, the drive device may drive to-be-driven bodies other than the lens frame 2. FIG.

It is sectional drawing of 1st Embodiment of the drive device which concerns on this invention. It is sectional drawing along the II-II line of FIG. It is sectional drawing along the III-III line of FIG. FIG. 2 is a perspective view around a piezoelectric element of the drive device of FIG. 1. It is sectional drawing of 2nd Embodiment of the drive device which concerns on this invention. It is sectional drawing along the VI-VI line of FIG. It is sectional drawing along the VII-VII line of FIG. It is sectional drawing along the VIII-VIII line of FIG. FIG. 6 is a perspective view of the periphery of a piezoelectric element unit of the drive device of FIG. 5. FIG. 6 is a front view of the periphery of the piezoelectric element unit of the drive device of FIG. 5. It is a circuit diagram of the drive circuit which operates the piezoelectric element of the drive device of FIG. It is a wave form diagram of the input signal input into the drive circuit of FIG. It is a wave form diagram of the output signal output from the drive circuit of FIG. It is a front view of the periphery of the piezoelectric element unit of the drive device of a modification. It is sectional drawing of the piezoelectric element unit periphery of the drive device of a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Drive device, 2 ... Lens frame (driven body), 4 ... Holder (support body), 5 ... Piezoelectric element (electromechanical conversion element), 6 ... Drive shaft (drive member), 7 ... Flexible printed circuit board, 8 ... conductive adhesive, 9 ... reinforcing plate (reinforcing member).

Claims (7)

An electromechanical transducer that expands and contracts along a predetermined expansion and contraction direction;
A drive member attached to one end of the electromechanical transducer in the expansion and contraction direction;
A driven body frictionally engaged with the driving member;
A printed circuit board for transmitting an electrical signal for driving the electromechanical transducer,
The electromechanical transducer is attached to the surface of the printed circuit board so that the expansion / contraction direction is substantially parallel to the surface of the printed circuit board, and is electrically connected to the printed circuit board. .   In the portion where the electromechanical conversion element is attached, the length of the printed circuit board in the expansion / contraction direction is equal to the length of the electromechanical conversion element in the expansion / contraction direction, or of the electromechanical conversion element in the expansion / contraction direction. The driving device according to claim 1, wherein the driving device is shorter than the length.   The drive device according to claim 1, wherein the printed circuit board is a flexible printed circuit board.   The drive device according to claim 1, wherein the electromechanical conversion element is electrically connected to the printed circuit board by a conductive adhesive.   5. The electromechanical conversion element is supported by an elastic member from a side with respect to the expansion / contraction direction at a portion facing the portion to which the printed circuit board is attached. The drive device according to one item. An electromechanical transducer that expands and contracts along a predetermined expansion and contraction direction;
A drive member attached to one end of the electromechanical transducer in the expansion and contraction direction;
A driven body frictionally engaged with the driving member;
The electromechanical conversion element is electrically connected by a conductive adhesive, and a printed circuit board that transmits an electric signal for driving the electromechanical conversion element;
A support for supporting the electromechanical transducer,
The support device supports the electromechanical conversion element by fixing the printed circuit board to the support.   The drive device according to claim 6, wherein the printed circuit board is a flexible printed circuit board, and is fixed to the support through a reinforcing member.

Images