JP5358415B2 - Driving device and optical device - Google Patents

Abstract

The invention provides a drive device and the driving method thereof, and an optical device. The drive device comprises a piezoelectric component, a driving shaft, a driven component in friction clamp connection with the driving shaft, and a control part applying driving signals on the piezoelectric component. When moving a part to be moved, the control part applies a common driving signal on the piezoelectric component. At the same time, a mute control driving signal is applied on the piezoelectric component (1). The mute control driving signal gradually changes the counterclockwise charging and timing driving signal of the common driving signal, when the part to be moved does not move towards the opposite direction of the normal driving direction of the common driving signal. The mute control driving signal is applied during a specified period before the common driving signal is applied and after the common driving signal is applied.

Description

  The present invention relates to a driving device that drives a driven member and an optical device including the driving device.

  As a conventional driving device, there is known a driving device that includes an actuator having a piezoelectric element (electromechanical conversion element) that expands and contracts by a driving signal, and outputs a driving signal to the actuator to control a moving speed of a driven member. (For example, refer to Patent Document 1). The driving device described in Patent Document 1 is controlled so that the driving speed is gradually increased by controlling the electric charge applied to the piezoelectric element by gradually increasing the time for applying the driving pulse signal to the piezoelectric element at the start of driving. At the same time, when the drive is stopped, the time for applying the drive pulse signal to the piezoelectric element is gradually reduced to control the electric charge applied to the piezoelectric element so that the drive speed is gradually reduced. The driving device described in Patent Document 1 controls the voltage applied to the piezoelectric element gradually at the start of driving so as to gradually increase the driving speed, and gradually increases the voltage applied to the piezoelectric element when the driving is stopped. It is controlled so that the driving speed gradually decreases by decreasing the speed.

Japanese Patent No. 3358418

  However, in the drive device described in Patent Document 1, it is necessary to control to gradually change the pulse width of the drive pulse signal or the applied voltage in order to reduce the operation sound of the drive device. For this reason, the control for reducing the operating noise may be complicated. Further, in the driving device described in Patent Document 1, since the moving speed is adjusted by controlling the electric charge applied to the piezoelectric element, for example, when the capacitance of the piezoelectric element changes due to a temperature change In addition, when the capacitance of the piezoelectric element changes due to individual difference variation, the speed control operation may become unstable.

  Therefore, the present invention has been made to solve such a technical problem, and it is possible to reduce the operating noise by simple control and to stably reduce the operating noise. It is an object of the present invention to provide a possible drive device and optical device.

  That is, the drive device according to the present invention includes an electromechanical transducer that expands and contracts according to a drive signal, a drive shaft that is attached to the electromechanical transducer and reciprocates according to the expansion and contraction of the electromechanical transducer, and the drive A driven member that is frictionally engaged with a shaft and moves by a reciprocating motion of the drive shaft, and a drive signal control circuit that applies the drive signal to the electromechanical transducer, the drive signal control circuit comprising: When the driven member is moved, the interval from the forward charging timing to the backward charging timing of the electromechanical transducer is different from the interval from the backward charging timing to the next forward charging timing. 1 drive signal is applied to the electromechanical transducer, and a period immediately before starting, which is a period immediately before the application of the first drive signal is started. The driven member is driven by the first drive signal only during the reverse charging timing of the first drive signal in at least one predetermined period of time immediately after the end of application of the first drive signal. The second drive signal, which is gradually changed in a range in which it does not move in the direction opposite to the direction to be applied, is applied to the electromechanical conversion element.

  In the driving apparatus according to the present invention, in order to move the driven member, the interval from the forward charging timing to the reverse charging timing of the electromechanical transducer and the interval from the reverse charging timing to the next forward charging timing. And a second drive signal obtained by gradually changing only the reverse charging timing in the first drive signal in at least one of the predetermined periods immediately before and immediately after the application of the first drive signal. Apply. The reverse charging timing of the second drive signal is controlled so as to gradually change within a range in which the driven member does not move in the direction opposite to the direction driven by the first drive signal. The moving speed can be controlled to gradually increase or decrease gradually. For this reason, the frictional coupling between the drive shaft and the driven member can be weakened before the driven member starts to move by the first drive signal and after the movement is finished. The driving member can be moved smoothly, and the driven member being moved can be smoothly stopped. Therefore, it is possible to reduce the operation noise by a simple control of controlling only the reverse charging timing in the first drive signal without controlling the pulse width and voltage of the drive signal. Further, since the pulse width and voltage of the drive signal are not controlled, the electromechanical conversion element can be sufficiently charged with the second drive signal as well as the first drive signal. Even when the capacitance of the conversion element changes, it is possible to stably reduce the operating noise.

  Here, when the second drive signal is applied in the period immediately before the start, the drive signal control circuit and the reverse charge timing in the second drive signal and the first It is preferable that the reverse charge timing in the second drive signal is changed so that a difference from the reverse charge timing in the one drive signal is small. By configuring in this way, it is possible to weaken the frictional coupling between the drive shaft and the driven member before the driven member starts to move by the first drive signal, so that the driven member being stopped is stopped. The member can be moved smoothly, and the operation of the driven member can be made smooth at the switching timing between the first drive signal and the second drive signal.

  Further, when the second drive signal is applied in the period immediately after the end, the drive signal control circuit and the first charge timing in the second drive signal as the end of the period immediately after the end approaches the first charge signal. It is preferable that the reverse charge timing in the second drive signal is changed so that a difference from the reverse charge timing in the drive signal becomes large. By configuring in this way, it is possible to weaken the frictional coupling between the drive shaft and the driven member after the driven member has finished moving by the first drive signal. The member can be smoothly stopped and the operation of the driven member can be made smooth at the switching timing between the first drive signal and the second drive signal.

  An optical device according to the present invention includes the above-described driving device, and controls the optical element to move in the optical axis direction or a direction orthogonal to the optical axis direction in conjunction with the driven member. Configured to do. According to this optical device, since the drive device described above is provided, it is possible to reduce the operating noise.

  According to the present invention, it is possible to reduce the operating noise by simple control, and it is possible to stably reduce the operating noise.

It is a schematic diagram of an imaging device concerning an embodiment of the present invention. It is sectional drawing which shows the imaging device which concerns on embodiment of this invention. It is sectional drawing of the to-be-driven member in III-III of FIG. 3 is an outline of an actuator drive circuit in the imaging apparatus shown in FIG. FIG. 3 is a waveform diagram of drive signals input to the piezoelectric element in FIG. 2. 5 is a setting example and a waveform setting example of a register in FIG. FIG. 5 is a schematic diagram for explaining a drive signal by an actuator drive circuit in FIG. 4 and an element current by the drive signal. It is a schematic diagram explaining the drive signal by the actuator drive circuit in FIG. 3 is a flowchart showing an operation of the imaging apparatus shown in FIG. It is a setting example of a register when changing the pulse width of the drive signal. It is an outline of an actuator drive circuit capable of changing the voltage of the drive signal. It is the schematic explaining the drive signal which changes a voltage, and the element current by the said drive signal. It is a schematic diagram explaining the drive signal which changes a pulse width, and the element current by the said drive signal. It is a graph which shows the temperature dependence of an electrostatic capacitance. It is a schematic diagram explaining the element current when an electrostatic capacitance changes with temperature changes. It is a schematic diagram explaining an element current when an electrostatic capacitance changes by individual difference variation.

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

  The imaging device (optical device) according to the present embodiment is suitably employed for an imaging device having a bending optical system, for example. In addition, the drive device according to the present embodiment is preferably employed, for example, in an imaging device in order to control the operation sound when the optical member moves. First, an outline of the imaging apparatus according to the present embodiment will be described. FIG. 1 is a schematic diagram illustrating an imaging optical system of the imaging apparatus according to the present embodiment.

  The imaging apparatus shown in FIG. 1 uses a bending optical system that bends the optical axis O, and includes a zoom lens unit 16, an imaging element 82, and a control unit 81. The zoom lens unit 16 includes an imaging optical system of the imaging apparatus, and includes a fixed lens 105, a prism 104, moving lenses (optical members) 90 and 102, and a fixed lens 101. The control unit 81 controls the entire imaging apparatus, and includes, for example, a CPU (Central Processing Unit) 62, an ISP (Image Signal Processing) 60, an element driving circuit 61, an EEPROM (Electrically Erasable PROM) 64, and a driver 65. ing.

  The moving lenses 90 and 102 are connected with a zoom actuator 10 and an autofocus (AF) actuator 15 as drive sources, respectively. When the actuators 10 and 15 are driven, the moving lenses 90 and 102 move along the optical axis O, thereby realizing a zoom function and an autofocus function. The actuators 10 and 15 are connected to a driver 65, and drive control is performed by the driver 65 and the CPU 62.

  The imaging element 82 is an imaging unit that is disposed on the optical axis O and converts an image formed by the photographing optical system of the zoom lens unit 16 into an electrical signal. The image sensor 82 is constituted by a CCD (Charge Coupled Device image sensor), for example, and is connected to the ISP 60.

  The image of the subject 106 incident on the zoom lens unit 16 is bent through the fixed lens 105 and the prism 104, and reaches the image sensor 82 through the moving lens 90, the moving lens 102, and the fixed lens 101, and the ISP 60 and It is processed as an image by the CUP 62.

  Here, the lens positions of the moving lenses 90 and 102 are detected by position detection elements 83 and 84 provided in the zoom lens unit 16. That is, the position detection elements 83 and 84 function as lens position detection means. The position detection elements 83 and 84 are connected to the element driving circuit 61 and are driven and controlled by the element driving circuit 61. The light intensity detected by each of the position detection elements 83 and 84 is output as an output signal via the element driving circuit 61 and is A / D converted by the A / D conversion unit 63 included in the CPU 62.

  The CPU 62 and the driver 65 feedback control the actuators 10 and 15 based on the A / D converted output signal, information stored in the EEPROM 64, and the like. Note that the EEPROM 64 stores output signals for the zoom position and AF position obtained, for example, by measurement during adjustment. As described above, the lens driving unit of the imaging apparatus is configured to be operable in cooperation with the position detecting unit.

  Next, the detail of each structure mentioned above is demonstrated. In the following, the details will be described by taking the moving lens 102 as an example in consideration of easy understanding.

  First, details will be described from the lens driving means of the imaging apparatus. FIG. 2 is a cross-sectional view of the driving device for the moving lens 102. The drive device shown in FIG. 2 has an actuator 10 having a drive shaft 2 attached to the piezoelectric element 1, and reciprocates the drive shaft 2 according to the expansion and contraction of the piezoelectric element 1, and is frictionally engaged with the drive shaft 2. It is a device that moves the drive member 3 along the drive shaft 2.

  The piezoelectric element 1 is an electromechanical conversion element that can be expanded and contracted by input of a drive signal, and can expand and contract in a predetermined direction. The piezoelectric element 1 is connected to the control unit 81 and expands and contracts when an electric signal is input by a driver (drive signal control circuit) 65. For example, the piezoelectric element 1 is provided with two input terminals 11a and 11b. By repeatedly increasing and decreasing the voltage applied to the input terminals 11a and 11b, the piezoelectric element 1 repeatedly expands and contracts. As the electromechanical conversion element, a material other than the piezoelectric element 1 such as a material made of a conductive polymer or a shape memory alloy may be used as long as it expands and contracts when a drive signal is input.

  The drive shaft 2 is attached to the piezoelectric element 1 with its longitudinal direction facing the expansion / contraction direction of the piezoelectric element 1. For example, one end of the drive shaft 2 is brought into contact with the piezoelectric element 1 and bonded using an adhesive 21. The drive shaft 2 is a long member, and for example, a cylindrical one is used. The drive shaft 2 is supported by a partition portion 4b and a partition portion 4c extending inward from the fixed frame 4 so as to be movable along the longitudinal direction. The partition part 4 b and the partition part 4 c are members for partitioning the moving region of the driven member 3, and also function as support members for the drive shaft 2. The fixed frame 4 functions as a housing for housing and assembling the piezoelectric element 1, the drive shaft 2, the driven member, and the like.

  A light and highly rigid material is suitable for the drive shaft 2. The shape of the drive shaft 2 is not limited to a cylindrical shape, and may be a prismatic shape.

  A through hole 4a through which the drive shaft 2 passes is formed in each of the partition portion 4b and the partition portion 4c. The partition portion 4 b supports a portion near the piezoelectric element 1 mounting portion of the drive shaft 2, that is, a base end portion of the drive shaft 2. The partition portion 4 c supports the tip portion of the drive shaft 2. When the drive shaft 2 is attached to the piezoelectric element 1, the drive shaft 2 reciprocates along its longitudinal direction in accordance with repeated operations of expansion and contraction of the piezoelectric element 1.

  FIG. 2 shows the case where the drive shaft 2 is supported by the partition portions 4b and 4c at two positions, that is, the distal end side and the proximal end side. However, the drive shaft 2 is supported on either the distal end side or the proximal end side. There is also a case to support. For example, by forming the through hole 4a of the partition portion 4b larger than the outer diameter of the drive shaft 2, the drive shaft 2 is supported only at the tip portion by the partition portion 4c. Further, by forming the through hole 4a of the partition portion 4c larger than the outer diameter of the drive shaft 2, the drive shaft 2 is supported only at the base end portion by the partition portion 4b.

  2 shows the case where the partition portions 4b and 4c that support the drive shaft 2 are integrated with the fixed frame 4, these partition portions 4b and 4c are separate from the fixed frame 4. You may attach to the fixed frame 4 and provide. Even in the case of separate bodies, the same functions and effects as in the case of being integrated can be obtained.

  The driven member 3 is movably attached to the drive shaft 2. The driven member 3 is attached by frictional engagement with the drive shaft 2 and is movable along the longitudinal direction of the drive shaft 2. For example, the driven member 3 is pressed against the drive shaft 2 by the leaf spring 7 and engaged with a predetermined coefficient of friction, and is pressed against the drive shaft 2 with a constant pressing force, so that the driven member 3 has a constant amount during its movement. It is attached so that a frictional force is generated. When the drive shaft 2 moves so as to exceed this frictional force, the driven member 3 maintains its position due to inertia, and the drive shaft 2 moves relative to the driven member 3.

  The piezoelectric element 1 is attached to the fixed frame 4 by a support member 5. The support member 5 supports and attaches the piezoelectric element 1 from the side with respect to the expansion / contraction direction, and is disposed between the piezoelectric element 1 and the fixed frame 4. In this case, the piezoelectric element 1 is preferably supported by the support member 5 from a direction orthogonal to the expansion / contraction direction. The support member 5 functions as an attachment member that supports and attaches the piezoelectric element 1 from the side.

  Thus, the actuator 10 is supported by the support member 5 from the side with respect to the expansion / contraction direction of the piezoelectric element 1, and both ends of the actuator 10 are free ends that can move in the expansion / contraction direction of the piezoelectric element 1. For this reason, even when the actuator 10 is driven, vibration due to expansion and contraction of the piezoelectric element 1 is difficult to be transmitted to the fixed frame 4 side. Therefore, it is effective to set the drive signal of the actuator 10 in association with the resonance frequency of the actuator 10 itself.

  The support member 5 is formed of an elastic body having a predetermined or higher elastic property, for example, a silicone resin. The support member 5 is configured by forming an insertion hole 5a through which the piezoelectric element 1 is inserted, and is assembled to the fixed frame 4 in a state where the piezoelectric element 1 is inserted through the insertion hole 5a. The support member 5 is fixed to the fixed frame 4 by bonding with an adhesive 22. Further, the fixing between the support member 5 and the piezoelectric element 1 is also performed by bonding with an adhesive. By configuring the support member 5 with an elastic body, the piezoelectric element 1 can be supported so as to be movable in the expansion / contraction direction. In FIG. 2, two support members 5 are shown on both sides of the piezoelectric element 1, but these support members 5 and 5 are shown in two by taking a cross section of the annular support member 5.

  The support member 5 may be fixed to the fixed frame 4 and the piezoelectric element 1 by pressing the support member 5 between the fixed frame 4 and the piezoelectric element 1 and pressing the support member 5. For example, the support member 5 is made of an elastic body, and is formed to be larger than between the fixed frame 4 and the piezoelectric element 1 and is press-fitted between them. Thereby, the support member 5 is disposed in close contact with the fixed frame 4 and the piezoelectric element 1. In this case, the piezoelectric element 1 is pressed by the support member 5 from both sides in the direction orthogonal to the expansion / contraction direction. Thereby, the piezoelectric element 1 is supported.

  Moreover, although the case where the supporting member 5 was formed with silicone resin was demonstrated here, you may comprise the supporting member 5 with a spring member. For example, a spring member may be arranged between the fixed frame 4 and the piezoelectric element 1 and the piezoelectric element 1 may be supported with respect to the fixed frame 4 by this spring member.

  A movable lens 102 is attached to the driven member 3 via a lens frame 91. The moving lens 102 constitutes a photographing optical system of the camera and is a moving object of the driving device. The moving lens 102 is provided integrally with the driven member 3 so as to move together with the driven member 3. On the optical axis O of the moving lens 102, a fixed lens or the like is disposed as described with reference to FIG. 1, and constitutes a photographing optical system of the camera. As the moving lens 102, for example, an autofocus lens is used.

  A weight member 6 is attached to the end of the piezoelectric element 1. The weight member 6 is a member for transmitting the expansion / contraction force of the piezoelectric element 1 to the drive shaft 2 side, and is attached to an end portion opposite to the end portion to which the drive shaft 2 of the piezoelectric element 1 is attached.

  The weight member 6 is a component that constitutes a part of the actuator 10. The weight member 6 is heavier than the drive shaft 2.

  The weight member 6 is made of a material having a Young's modulus smaller than that of the piezoelectric element 1 and the drive shaft 2. Note that an elastic adhesive is preferably used as an adhesive for fixing the weight member 6 and the piezoelectric element 1.

  Further, the weight member 6 is provided in a state where it is not supported and fixed to the fixed frame 4. That is, the weight member 6 is attached to the free end of the piezoelectric element 1 and is not directly supported or fixed to the fixed frame 4 and is also restrained in movement with respect to the fixed frame 4 via an adhesive or a resin material. So that it is not supported or fixed.

  3 is a cross-sectional view of a friction engagement portion of the driven member 3 in III-III in FIG. As shown in FIG. 3, the driven member 3 is attached to the drive shaft 2 by pressing the drive shaft 2 with a leaf spring 7. For example, a V-shaped groove 3 a for positioning the drive shaft 2 is formed in the driven member 3. A sliding plate 3b having a V-shaped cross section is disposed in the groove 3a, and the drive shaft 2 is pressed against the driven member 3 through the sliding plate 3b.

  A sliding plate 3c having a V-shaped cross section is disposed between the leaf spring 7 and the driven member 3, and the leaf spring 7 presses the driven member 3 through the sliding plate 3c. . For this reason, the sliding plates 3b and 3c are arranged with the concave portions facing each other, and are provided with the drive shaft 2 interposed therebetween. By housing the drive shaft 2 in the V-shaped groove 3 a, the driven member 3 can be stably attached to the drive shaft 14.

  As the leaf spring 7, for example, a leaf spring material having an L-shaped cross section is used. One side of the leaf spring 7 is hooked on the driven member 3 and the other side is disposed at a position opposite to the groove 3 a, so that the driving shaft 2 accommodated in the groove 3 a by the other side is connected to the driven member 3. Can be pinched.

  In this way, the driven member 3 is frictionally engaged with the drive shaft 2 by attaching the driven member 3 to the drive shaft 2 side with a certain force by the leaf spring 7. That is, the driven member 3 is attached such that the driven member 3 is pressed against the drive shaft 2 with a constant pressing force, and a constant frictional force is generated during the movement.

  Further, by sandwiching the drive shaft 2 by the sliding plates 3b and 3c having a V-shaped cross section, the driven member 3 comes into line contact with the drive shaft 2 at a plurality of locations, and the drive shaft 2 is stably frictioned. Can be engaged. Further, since the driven member 3 is engaged with the drive shaft 2 by a plurality of line contact states, substantially the same relationship as when the driven member 3 is engaged with the drive shaft 2 in a surface contact state. In this state, stable friction engagement can be realized.

Next, the details of the driver 65 that controls the operation of the actuator 10 described above will be described. FIG. 4 is a schematic diagram of the driver 65 that operates the piezoelectric element 1. As shown in FIG. 4, the driver 65 includes a drive circuit 65c that operates the piezoelectric element 1, a logic 65a that is a logic circuit that drives the drive circuit 65c, and a register memory 65b that stores setting contents of the logic 65a. . Logic 65a inputs the control signal _{S IN} from the CPU 62, and records in the register memory 65b, and outputs an electrical signal for driving the drive circuit 65c. The drive circuit 65 c functions as a drive circuit for the piezoelectric element 1 and outputs an electrical signal for driving to the piezoelectric element 1. The drive circuit 65c receives a control signal from the logic 65a, a voltage amplification or a current amplification of the control signal, and outputs an electric signal for driving the piezoelectric element 1. The drive circuit 65c is provided with a field effect transistor (FET). The transistor is configured to output Hi output (high potential output), Lo output (low potential output), and OFF output (off output, open output) as output signals. The drive circuit shown in FIG. 4 is an example of a circuit for operating the piezoelectric element 1, and the piezoelectric element 1 may be operated using a circuit other than this.

FIG. 5 is an example of a drive signal output from the drive circuit 65c, and the horizontal axis is time. The signal in FIG. 5 is a signal that is output based on an input signal from the logic 65a and that moves the driven member 3. The drive signal shown in FIG. 5 includes an output signal (first pulse signal) A _OUT and an output signal (first pulse signal) output when the driven member 3 is moved in the direction in which the driven member 3 approaches the piezoelectric element 1 (the right direction in FIG. 2). 2 pulse signal) B _OUT (signal during forward rotation).

In FIG. 5, each of the two pulse signals A _OUT and B _OUT is a signal that is input to two terminals (see FIGS. 1 and 4) of the piezoelectric element 1 and is a signal that constitutes a drive signal. These two pulse signals have the same frequency f (period T), and by making their phases different from each other, the potential difference between the two signals changes stepwise in one direction, and rapidly changes in the opposite direction. The signal or the potential difference between the signals suddenly changes in one direction, and the signal changes stepwise in the opposite direction. The potential difference between A _OUT and B _OUT becomes the input voltage of the piezoelectric element 1. The piezoelectric element 1 expands or contracts due to the potential difference between these pulse signals. Continuous driving is performed by continuously inputting signals for each pulse to the first actuator 8.

The pulse signals A _OUT and B _OUT are set so that, for example, one signal becomes a Hi output and drops to a Lo output, and then the other signal becomes a Hi output. Among these signals, when one signal becomes Lo output, the other signal is set to Hi output after a certain time lag t _OFF has elapsed. That is, the pulse signal B _OUT is delayed by a time lag t _OFF compared to the pulse signal A _OUT . By controlling this time lag t _OFF , the ratio of the interval from the forward charging timing to the reverse charging timing of the piezoelectric element 1 and the interval from the reverse charging timing to the next forward charging timing can be controlled. It is configured. A drive signal (a signal at the time of reverse rotation) that is output when the driven member 3 is moved away from the piezoelectric element 1 can be generated by controlling the time lag t _OFF as described later. Further, by controlling this time lag, a silent control drive signal that is output in the silent control for reducing the operating noise of the piezoelectric element 1 is generated. The application time of the Hi output and the Lo output of the pulse signals A _OUT and B _OUT are set using the register memory 65 b provided in the driver 65.

FIG. 6A shows an example of register settings stored in the register memory 65b. As shown in FIG. 6A, in the register memory 65b, how to control the waveform, operation, and time of the output signal is set by the operation selection bit, the waveform selection bit, and the time selection bit. . In addition, since arbitrary settings are made regarding the time selection bit, the description of the settings is omitted. The register memory 65b stores a normal output signal setting for moving the driven member 3. For example, the output signal _{A OUT} of the pulse width t1, the output signal _{B OUT} time lag _{t OFF} to the output signal _{A OUT,} a pulse width t2 of the output signal _{B OUT,} so that the output signal _{A OUT,} the period T of _{B OUT} shown in Table Is set to In addition to normal output signal settings, four static sound wave pattern settings related to output signals used to reduce operating noise are stored. In these static sound waves, only the time lag t _OFF of the output signal B _OUT with respect to the output signal A _OUT is set. The pulse width t 1 of the output signal A _OUT , the pulse width t 2 of the output signal B _OUT , and each output signal A _OUT , The B _OUT cycle T is the same as the normal output signal setting. By using the setting example shown in FIG. 6A, the setting shown in FIG. 6B is made. As shown in FIG. 6 (b), the normal waveform, the pulse width t1 of the output signal _{A OUT} is a, time lag _{t OFF} of the output signal _{B OUT} for the output signal _{A OUT} is b, the pulse width t2 of the output signal _{B OUT} c, the period T of each of the output signals A _OUT and B _OUT is d. In the static sound waves 1 to 4, only the normal waveform and the time lag t _OFF are changed. For example, the time lag t _OFF is b1 (> b) in the static sound form 1, the time lag t _OFF is b2 (> b1) in the static sound form 2, the time lag t _OFF is b3 (> b2) in the static sound form 3, and the time lag t in the static sound form 4 _OFF is set to b4 (> b3).

Next, the normal waveform set in FIG. 6 and the element currents of the ultrasonic waves 1 to 4 will be described. FIG. 7 is a schematic diagram showing a normal waveform in normal driving and a device current of the static acoustic waves 1 to 4 in silent driving. FIG. 7A shows the device current having a normal waveform, and FIGS. 7B to 7E show the device currents of the static acoustic wave types 1 to 4. As shown in FIG. 7, in the static sound waves 1 to 4, the time lag t _OFF is changed to b1 to b4, so that only the reverse charging timing is changed while maintaining the current waveform and the peak. By gradually changing the time lag t _OFF in the order of the static sound waves 1 to 4, the reverse charging timing gradually approaches the middle between the forward charging timings. The driving speed (moving speed of the driven member 3) decreases as the reverse charging timing gradually approaches the middle between the forward charging timings. For this reason, the driving speed of the normal waveform is the fastest, and the driving speed gradually decreases in the order of the static sound waves 1, 2, 3, and 4. That is, the moving speed of the driven member 3 can be controlled by using a driving signal combined with a static sound waveform.

On the other hand, the driven member 3 stops when the reverse charging timing is positioned between the forward charging timings. At this time, the pulse signals A _OUT and B _OUT have a time from when the potential difference between the signals changes in one direction until it changes in the opposite direction, and from when it changes in the opposite direction until it changes again in one direction. Are the same signal. That is, the interval from the forward charging timing to the backward charging timing of the piezoelectric element 1 is the same as the interval from the backward charging timing to the next forward charging timing. Due to the potential difference between these pulse signals, the piezoelectric element 1 repeats expansion and contraction alternately at regular intervals. The driven member 3 stops in a slightly lifted state (vibration stagnation state) as the drive shaft 8b continuously expands and contracts at equal intervals and vibrates.

  When the reverse charging timing exceeds the middle between the forward charging timings, the driven member 3 moves in the reverse direction. For this reason, in order to make the movement direction by the static sound waves 1 to 4 coincide with the movement direction by the normal waveform, the time lags b1 to b4 of the static sound waves 1 to 4 are changed within a range in which the driven member 3 does not move in the reverse direction. It is necessary to That is, as shown in FIG. 7A, the interval from the reverse charge timing to the next forward charge timing is larger than the interval from the positive charge timing to the reverse charge timing of the piezoelectric element 1. Thus, when the time lag b in the normal waveform is set, the time lags b1 to b4 of the electrostatic waveforms 1 to 4 are more than the interval from the forward charge timing to the reverse charge timing of the piezoelectric element 1. Range in which the interval from the reverse charge timing to the next forward charge timing is not smaller (the interval from the positive charge timing to the reverse charge timing of the piezoelectric element 1, and the reverse charge from the reverse charge timing to the next positive charge) (Including the case where the interval to the timing is the same). For example, in the normal waveform shown in FIG. 7A, the ratio of the interval from the forward charging timing to the backward charging timing of the piezoelectric element 1 and the interval from the backward charging timing to the next forward charging timing is It is assumed that it is 20:80. In this case, for example, in the static acoustic wave types 1 to 4, the ratio of the interval from the forward charging timing to the reverse charging timing of the piezoelectric element 1 and the interval from the reverse charging timing to the next forward charging timing is It is set to 25:75, 30:70, 40:60, 50:50.

  Next, a case where the driven member 3 is operated in the reverse direction will be described. Thus, the time lag b in the normal waveform is such that the interval from the reverse charge timing to the next positive charge timing is smaller than the interval from the positive charge timing to the reverse charge timing of the piezoelectric element 1. Is set, the time lags b1 to b4 of the electrostatic waveforms 1 to 4 are set to the next positive charge timing from the reverse charge timing rather than the interval from the positive charge timing to the reverse charge timing of the piezoelectric element 1. Range in which the interval until the direction charging timing does not become larger (the interval from the forward charging timing to the reverse charging timing of the piezoelectric element 1 is the same as the interval from the reverse charging timing to the next forward charging timing. (Including cases). For example, in the normal waveform, the ratio of the interval from the forward charging timing to the reverse charging timing of the piezoelectric element 1 and the interval from the reverse charging timing to the next forward charging timing is 80:20. . In this case, for example, in the static acoustic wave types 1 to 4, the ratio of the interval from the forward charging timing to the reverse charging timing of the piezoelectric element 1 and the interval from the reverse charging timing to the next forward charging timing is 75. : 25, 70:30, 60:40, and 50:50.

When the driving signals are combined with the static sound wave forms 1 to 4, they are combined so that the time lag t _OFF gradually becomes smaller or larger. When the normal waveform and the static waveform are connected, a static waveform having a reverse charge timing close to the reverse charge timing of the normal waveform is used. For example, in the case of the normal waveform shown in FIG. 7A, the static sound waveform shown in FIG. 7B is used.

  FIG. 8 is an example of a drive signal for reducing operating noise. FIG. 8A is an example in which a silent drive period is provided in a predetermined period immediately before the start of the normal drive period, and FIG. 8B is an example in which the silent drive period is provided in a predetermined period immediately after the end of the normal drive period. It is an example. As shown in FIG. 8A, in the silent drive period immediately before the start of application of the normal drive signal (first drive signal) using the normal waveform, the silent drive 4 using the static sound form 4 and the static sound form 3 were used. A drive signal (second drive signal) in which a pulse signal for silent control is arranged in the order of the silent drive 3, the silent drive 2 using the static acoustic waveform 2, and the silent drive 1 using the static acoustic waveform 1 is applied. That is, as the silent drive period ends, the quiet control pulse signal is changed so that the difference between the reverse charge timing in the quiet control pulse signal and the reverse charge timing in the normal drive pulse signal becomes smaller. The As a result, the frictional coupling between the drive shaft 2 and the driven member 3 can be weakened, so that the stopped driven member 3 can be moved smoothly, and a normal drive pulse signal and The operation of the driven member 3 can be made smooth at the switching timing with the pulse signal for silent control.

  Further, as shown in FIG. 8B, in the silent drive period immediately after the application of the normal drive signal using the normal waveform, the silent drive 1 using the static sound form 1, the silent drive 2 using the static sound form 2, A drive signal in which pulse signals for quiet control are arranged in the order of the silent drive 3 using the static sound waveform 3 and the silent drive 4 using the static sound waveform 4 is applied. That is, as the silent drive period ends, the quiet control pulse signal is changed so that the difference between the reverse charge timing in the quiet control pulse signal and the reverse charge timing in the normal drive pulse signal increases. The As a result, the frictional coupling between the drive shaft 2 and the driven member 3 can be weakened, so that the driven member being moved can be stopped smoothly, and the pulse signal for normal driving and the silent sound can be stopped. It is possible to smooth the operation of the driven member 3 at the switching timing with the control pulse signal.

  Next, the operation of the imaging apparatus according to the present embodiment will be described. FIG. 9 is a flowchart for explaining movement control of the driven member 3 of the imaging apparatus according to the present embodiment. In FIG. 9, a case where the moving lens 102 for autofocus is moved will be described as an example. The control process shown in FIG. 9 is executed by the control unit 81. For example, the movement instruction of the moving lens 102 is executed at the timing when it is output from the CPU 62.

As shown in FIG. 9, the CPU 62 first sets the number of times of driving the piezoelectric element 1 (S10). For example, the CPU 62 sets the number of times of silent control driving immediately before the start of movement, the number of times of normal driving during movement, and the number of times of silent control driving immediately after the end of movement. For example, 4 is set as the number of times of silent control driving. After setting the number of times of driving, the CPU 62 sets the pulse time of a normal driving signal (S12). For example, the CPU 62 sets the pulse widths t1 and t2, the time lag t _OFF , and the period T of the normal waveform to a, c, b, and d, respectively. Thereafter, the pulse time (time lag t _OFF ) of the static sound waveform 1 is set to b1, for example (S14). Thereafter, the pulse time (time lag t _OFF ) of the static sound waveform 2 is set to b2, for example (S16). Thereafter, the pulse time (time lag t _OFF ) of the static sound waveform 3 is set to b3, for example (S18). Thereafter, the pulse time (time lag t _OFF ) of the static sound waveform 4 is set to b4, for example (S20).

Then, the CPU 62 transmits the setting value set in the processing of S10 to S20 to the driver 65. The logic 65a changes the set value of the register memory 65b. Then, the CPU 62 transmits a drive start signal to the driver 65 (S22). The driver 65 selects and applies a static sound wave form (here, the static sound wave form 4) having the largest time lag t _OFF among the static sound wave forms 1 to 4 for silent control set in the processes of S14 to S18 (S24). Then, the number of times of driving is counted and compared with the number of times of silent control driving immediately before the start of movement set in the process of S10 (S26). When the count value is less than the number of times of silent control driving, the process proceeds to S24 again. In the process of S24, the driver 65 selects and applies a static sound wave form having the largest time lag t _OFF (here, the static sound wave form 3) among the static sound wave forms 1 to 3 for silent control that have not yet been selected. In this way, the applied static sound wave time lag t _OFF is applied so as to be gradually reduced, and the drive signal shown in FIG.

  In the process of S26, when the count value reaches the number of times of silent control drive, the driver 65 applies the normal drive signal set in the process of S12 (S28). Then, the number of times of driving is counted and compared with the number of times of normal driving in the movement set in the process of S10 (S30). The process of S28 is repeatedly executed until the count value reaches the normal drive count.

In the process of S26, when the count value reaches the number of times of normal driving, the driver 65 is silent with the smallest time lag t _OFF among the silent sound forms 1 to 4 for silent control set in the processes of S14 to S18. A waveform (here, a static sound waveform 1) is selected and applied (S32). Then, the number of times of driving is counted and compared with the number of times of silent control driving immediately after the end of movement set in the process of S10 (S34). When the count value is less than the number of times of silent control driving, the process proceeds to S32 again. In the process of S32, the driver 65 selects and applies a static sound wave form having the smallest time lag t _OFF (here, the static sound wave form 2) among the static sound wave forms 2 to 4 for silent control not yet selected. In this way, the applied static sound wave type time lag t _OFF is applied so as to increase gradually, and the drive signal shown in FIG. In the process of S34, when the count value reaches the silent control drive count, the control process shown in FIG. 9 is terminated.

  As described above, by executing the control process shown in FIG. 9, the drive signal shown in FIG. 8A is applied before the start of driving, and the drive signal shown in FIG. 8B is applied after the end of driving.

  As described above, in the drive device and the imaging device according to the present embodiment, in order to move the driven member 3, the interval from the forward charge timing to the reverse charge timing of the piezoelectric element 1 and the reverse charge timing are used. Silent control drive that applies a normal drive signal with a different interval until the next forward charge timing, and gradually changes only the reverse charge timing in the normal drive signal in a predetermined period immediately before and after the application of the normal drive signal. Apply a signal. The reverse charge timing of the silent control drive signal is controlled so as to gradually change within a range in which the driven member 3 does not move in the direction opposite to the direction driven by the normal drive signal. For example, the driven member 3 The moving speed can be gradually increased or decreased gradually. For this reason, the frictional coupling between the drive shaft 2 and the driven member 3 can be weakened before the driven member 3 starts to move by the normal drive signal and after the movement is finished. The driven member 3 can be smoothly moved, and the driven member 3 being moved can be smoothly stopped.

In addition, according to the driving device and the imaging device according to the present embodiment, the configuration necessary for silent control can be simplified. To generate the silent control driving signal, in addition to the control of the time lag t _OFF, for example, it is conceivable to change the pulse width or voltage of the drive signal. For example, as shown in FIG. 13, the pulse widths t1 and t2 and the time lag t _OFF of the drive pulse signal are set to a1 to a4 (a1>a2>a3> a4), c1 to c4 (c1>c2>c3> c4), b1 to b4 (b1>b2>b3> b4) or gradually change the voltage V of the drive pulse signal to V1 to V4 (V1>V2>V3> V4) as shown in FIG. Can be considered.

However, when changing the pulse width of the drive signal must change the pulse width t1, t2 and time lag t _OFF of electrostatic sound waveform 1-4. FIG. 10 shows an example of register settings used when controlling the pulse width. As shown in FIG. 10, a register for controlling the pulse widths t <b> 1 and t <b> 2 of the static acoustic waves 1 to 4 is required as compared with the register setting example shown in FIG. For this reason, the register setting process (S14 to S20) related to the static sound waveform shown in FIG. 9 increases, so that the processing load increases and the capacity of the register memory 65b may be compressed. Further, when voltage control is performed, a voltage circuit is required. FIG. 11 is an example of the driver 65 used when controlling the voltage. As shown in FIG. 11, when the voltage is controlled, it is necessary to include the step-down circuits 1 to 4, so that the circuit scale may increase as compared with the driver 65 shown in FIG. 4. On the other hand, according to the drive device and the imaging device according to the present embodiment, simple control and simple control of controlling only the reverse charging timing in the normal drive signal without controlling the pulse width and voltage of the drive signal. With a simple configuration, it is possible to reduce the operating noise.

As shown in FIGS. 12 and 13, when the pulse width of the drive pulse signal is reduced or the voltage is reduced, the device current waveform is deformed. For this reason, when the capacitance changes, the operation noise reduction operation may not be performed stably. FIG. 14 is a graph showing the temperature dependence of capacitance. Capacitances C _{1 to} C ₅ indicate the temperature dependence of the capacitance of a given material. As shown in FIG. 14, the capacitance tends to increase as the temperature increases. For this reason, the peak intensity of the device current may change at a high temperature and a low temperature as compared with a normal temperature.

FIG. 15 is a graph showing the element current with respect to the silent control drive signal for each temperature. FIG. 15A shows a silent control drive signal in which only the time lag t _OFF is controlled, and is a silent sound waveform of the silent drive 4 shown in FIG. FIG. 15B shows a silent control drive signal in which only the voltage is controlled, and is a silent sound form of the silent drive 4 shown in FIG. FIG. 15C shows a silent control drive signal in which the pulse widths t1 and t2 and the time lag t _OFF are controlled, and is a silent sound form of the silent drive 4 shown in FIG. In FIGS. 15A to 15C, (a) shows a device current at normal temperature, (b) shows a device current at low temperature, and (c) shows a device current at high temperature.

  When the silent control drive signal is generated by voltage control, the peak intensity of the element current at room temperature is h2, as shown in FIG. As shown in this element current waveform, since the voltage V4 is small, the piezoelectric element 1 is discharged in a state where it is not sufficiently charged. Since the capacitance becomes small at low temperature, the peak intensity of the element current at low temperature is h3 which is larger than h2. Further, since the capacitance increases at a high temperature, the peak intensity of the device current at a high temperature is h4 which is smaller than h2. As described above, the peak intensity greatly changes due to the temperature change.

  Further, when the silent control drive signal is generated by controlling the pulse width and the time lag, the peak intensity of the element current at room temperature is h5 as shown in FIG. As shown in this element current waveform, since the pulse width a4 is small, the piezoelectric element 1 is discharged in a state where it is not sufficiently charged. Since the capacitance becomes small at low temperatures, the peak intensity of the device current at low temperatures is h6 which is larger than h5. Further, since the capacitance increases at a high temperature, the peak intensity of the device current at a high temperature is h7 which is smaller than h5. As described above, the peak intensity greatly changes due to the temperature change.

  On the other hand, when the silent control drive signal is generated by controlling only the time lag, the piezoelectric element 1 is sufficiently charged as shown in the element current waveform at room temperature in FIG. You can see that For this reason, even if the capacitance changes at low and high temperatures, the peak intensity h1 can be maintained without being changed. In this way, a stable silent control operation can be performed by controlling only the time lag.

In addition, there may be a case where the capacitance of the piezoelectric element 1 changes due to variation in individual differences. FIG. 16 is a graph showing the element current with respect to the silent control drive signal for each capacitance. FIG. 16A shows a silent control drive signal in which only the time lag t _OFF is controlled, and is a silent sound waveform of the silent drive 4 shown in FIG. FIG. 16B shows a silent control drive signal in which only the voltage is controlled, and is a silent sound form of the silent drive 4 shown in FIG. FIG. 16C shows a silent control drive signal in which the pulse widths t1 and t2 and the time lag t _OFF are controlled, and is a silent sound form of the silent drive 4 shown in FIG. 16 (A) to 16 (C), (a) is the element current of the piezoelectric element 1 having a typical capacitance, (b) is the element current of the piezoelectric element 1 having the lowest capacitance, and (c) is the element current. This is the element current of the piezoelectric element 1 having the highest capacitance. When controlling only the voltage or when controlling the pulse width and the time lag, the charge peak intensity varies due to the difference in capacitance as in FIG. On the other hand, when the silent control drive signal is generated by controlling only the time lag, as shown in the element current waveform of the piezoelectric element 1 having a typical capacitance in FIG. The battery is discharged in a fully charged state. For this reason, even if the capacitance changes at low and high temperatures, the peak intensity h1 can be maintained without being changed. In this way, a stable silent control operation can be performed by controlling only the time lag.

  The above-described embodiment shows an example of the drive device and the optical device according to the present invention. The drive device and the optical device according to the present invention are not limited to the drive device and the optical device according to the embodiment, and the drive device and the optical device according to the embodiment are within a range not changing the gist described in each claim. It may be modified or applied to others.

  For example, in the above-described embodiment, the case of applying to the movement of the moving lens 102 for autofocus has been described. However, the embodiment may be applied to the movement of the moving lens 90 for zooming, the zoom lens unit unit 16, and the like. Further, the present invention may be applied when an object other than the moving lens 90 (for example, a stage or a probe) is moved. Furthermore, the present invention may be applied to position detection when driving in a direction orthogonal to the optical axis, such as a camera shake correction mechanism.

  In the above-described embodiment, an example in which the optical apparatus is preferably used in an imaging apparatus has been described. However, the optical apparatus may be used in an ink jet print head.

  In the above-described embodiment, the case where the piezoelectric element 1 is attached to the fixed frame 4 via the support member 5 and the end of the piezoelectric element 1 is a free end has been described. However, the end of the piezoelectric element 1 is directly fixed. It may be attached to the frame 4.

  In the above-described embodiment, the example in which the silent control drive signal is applied in the predetermined period immediately before and after the application of the normal drive signal has been described. For example, the silent control drive signal is applied only in the predetermined period immediately before the start of the application of the normal drive signal. May be applied, or the silent control drive signal may be applied only for a predetermined period immediately after the application of the normal drive signal.

  Further, in the above-described embodiment, an actuator using a piezoelectric element is employed as an actuator of the imaging apparatus, but other driving parts such as a motor, a polymer actuator, and a shape memory alloy may be employed.

  DESCRIPTION OF SYMBOLS 1 ... Piezoelectric element (electromechanical conversion element), 2 ... Drive shaft, 3 ... Driven member, 10, 15 ... Actuator (drive source), 62 ... CPU, 65 ... Driver, 81 ... Control part (drive signal control circuit) , 83... Position detecting element, 102... Moving lens (optical member).

Claims (4)

An electromechanical transducer that expands and contracts in response to a drive signal;
A drive shaft attached to the electromechanical transducer and reciprocating in accordance with the expansion and contraction of the electromechanical transducer;
A driven member that is frictionally engaged with the drive shaft and moves by reciprocating movement of the drive shaft;
A drive signal control circuit for applying the drive signal to the electromechanical transducer;
With
The drive signal control circuit includes:
In the case of moving the driven member, the interval from the forward charging timing to the reverse charging timing of the electromechanical transducer is different from the interval from the reverse charging timing to the next forward charging timing. Applying a drive signal to the electromechanical transducer,
In the predetermined period of at least one of a period immediately before the start of application of the first drive signal and a period immediately after the end of application of the first drive signal, and a period immediately after the end of application of the first drive signal, the first A second drive signal obtained by gradually changing only the reverse charging timing in the drive signal in a range in which the driven member does not move in the direction opposite to the direction driven by the first drive signal is applied to the electromechanical conversion element. Applying to the
A drive device characterized by the above.   When the drive signal control circuit applies the second drive signal in the period immediately before the start, the reverse charge timing in the second drive signal and the first drive signal approach the end of the period immediately before the start. The drive device according to claim 1, wherein the reverse charge timing in the second drive signal is changed so that a difference between the reverse charge timing and the reverse charge timing is small.   When the drive signal control circuit applies the second drive signal in the period immediately after the end, the reverse charge timing in the second drive signal and the first drive signal approach the end of the period immediately after the end. The drive device according to claim 1 or 2, wherein the reverse charge timing in the second drive signal is changed so that a difference between the reverse charge timing and the reverse charge timing becomes large. A drive device according to any one of claims 1 to 3,
An optical apparatus, wherein the optical element is controlled to move in the optical axis direction or a direction orthogonal to the optical axis direction in conjunction with the driven member.

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