JP2017028933A - Control device, vibration type drive device, dust removal device, lens barrel, and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently drive a vibration type actuator by using a high harmonic wave.SOLUTION: A drive device 300 for a vibration type actuator 100 that comprises a driven body 101 and a vibration body 105, the vibration body 105 having two projection parts 102, an elastic body 103, and a piezoelectric element 104, comprises: a pulse signal generation circuit 301 that generates a pulse signal for driving the vibration body 105 by a tertiary high harmonic wave; and a step-up circuit 302 that amplifies the pulse signal generated by the pulse signal generation circuit 301 to generate an AC voltage to be applied to the piezoelectric element 104. The drive device 300 has such a configuration that a condition of fm/3≤fp≤fe/3 is satisfied when a resonance frequency of the vibration body 105 is defined as fm, a frequency of the pulse signal is defined as fp, and an electric resonance frequency generated by the step-up circuit 302 and the piezoelectric element 104 is defined as fe.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control device that drives a vibration type actuator, a vibration type drive device, a dust removing device including the vibration type drive device, a lens barrel, and an imaging device.

  An oscillating body having an oscillating body formed by bonding an electro-mechanical energy conversion element such as a piezoelectric element to an elastic body, and a driven body in pressure contact with the oscillating body, and excited by the oscillating body There is known a vibration type actuator that relatively moves the driven body and the driven body. The vibration body is excited by applying an AC voltage to the piezoelectric element. At that time, the vibration body is controlled by controlling the frequency, voltage value (voltage amplitude), phase difference, etc. of the AC voltage applied to the piezoelectric element. And the relative movement speed of the driven body can be controlled.

  A control device that drives a vibration type actuator includes a pulse signal generation circuit that generates a pulse signal, and a booster circuit that amplifies an output from the pulse signal generation circuit to a predetermined voltage value. The frequency of the pulse signal output from the pulse signal generation circuit (hereinafter referred to as “driving frequency”) has an upper limit depending on the performance of the switching element. Generally, the driving frequency increases as the circuit becomes more expensive and has a larger device area. It tends to be possible to generate a high pulse signal.

  On the other hand, the optimum vibration mode varies depending on the configuration (size, shape, etc.) of the vibrating body. For example, depending on the configuration of the vibrating body, a low resonance frequency is 20 kHz, and a high resonance frequency is 120 kHz. Therefore, in order to use a small and inexpensive pulse signal generation circuit, it is necessary to lower the resonance frequency of the vibrator, but in that case, the degree of freedom in designing the vibrator is also limited.

  To solve this problem, Patent Document 1 proposes a method of driving a vibrating body using harmonics, with the driving frequency being 1 / N of the resonance frequency of the vibrating body (N is a natural number of 2 or more). Yes. According to such a driving method, since the driving frequency can be reduced to 1 / N of the resonance frequency of the vibrating body, it becomes possible to use a small and inexpensive pulse signal generation circuit, and to design the vibrating body. The degree of freedom can be increased.

JP 2011-9797 A

  However, in the driving method of the vibration type actuator using the harmonics described in Patent Document 1, the vibration body can be driven. However, it is sufficient from the viewpoint of efficiency that a large driving force is generated with smaller power consumption. Is hard to say.

  An object of this invention is to provide the technique which improves the drive efficiency at the time of driving a vibration type actuator using a harmonic.

  One aspect of the present invention includes an oscillating body having an electro-mechanical energy conversion element and an elastic body joined to the electro-mechanical energy conversion element, and applying an AC voltage to the electro-mechanical energy conversion element. A control device that excites a predetermined vibration in the vibrating body, wherein the control device generates a pulse signal for driving the vibrating body with a third harmonic and generated by the generating means Boosting means for amplifying a pulse signal to generate the AC voltage, and the resonance frequency of the vibrating body is fm, the frequency of the pulse signal is fp, and the electric power generated by the boosting means and the electromechanical energy conversion element The control apparatus is characterized in that the condition of fm / 3 ≦ fp ≦ fe / 3 is satisfied when the resonance frequency is fe.

  According to the present invention, it is possible to realize a control device that improves the driving efficiency when driving a vibration type actuator using harmonics, thereby reducing the size and cost of the control device. The degree of freedom in designing the vibrating body can be increased.

It is a figure explaining the schematic structure and the drive principle of the linear vibration type actuator used as the drive object by the control apparatus which concerns on embodiment of this invention. It is a perspective view which shows schematic structure of the lens drive mechanism to which the vibration type actuator shown in FIG. 1 is applied. It is a figure which shows the circuit structure of the drive device which comprises the control apparatus based on 1st Embodiment of this invention which drives the vibration type actuator shown in FIG. It is a block diagram which shows the circuit structure of the control apparatus which concerns on 1st Embodiment of this invention of the vibration type actuator shown in FIG. 1 which has the drive device of FIG. It is a figure explaining the output (control amount) from the phase difference and frequency determination part which the control apparatus of FIG. 4 has. FIG. 4 is a diagram illustrating a relationship between an electric resonance frequency of the booster circuit and a drive signal output from the booster circuit in the drive device of FIG. 3. FIG. 4 is a diagram illustrating a relationship between a pulse width of a pulse signal, a fundamental wave in the drive signal, and a third harmonic in the drive device of FIG. 3. FIG. 5 is a diagram illustrating measurement results of driving speed and power supply power when the vibration type actuator of FIG. 1 is driven by the control device of FIG. 4. It is a figure which shows the breakdown of the power supply in each of the conventional drive device and the drive device of FIG. FIG. 5 is a diagram showing a circuit configuration of a drive device that constitutes a control device according to a second embodiment of the present invention that drives the vibration type actuator shown in FIG. 1 and a diagram showing frequency characteristics of a drive signal output from the drive device. is there. FIG. 2 is a perspective view illustrating a schematic configuration of the imaging apparatus main body and a perspective view illustrating a schematic configuration of an imaging unit provided in the imaging apparatus main body.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the vibration-type actuator refers to an actuator having a vibrating body including an electro-mechanical energy conversion element and having a configuration capable of driving a driven body by vibration excited by the vibrating body. In addition, the vibration type driving device refers to a device including a vibration type actuator and a control device for exciting predetermined vibrations in the vibration body of the vibration type actuator.

  FIG. 1 is a diagram illustrating a schematic configuration and a driving principle of a linear vibration actuator that is an example of an object to be driven by a control device according to an embodiment of the present invention. FIG. 1A is a perspective view showing a schematic configuration of the vibration type actuator 100. FIG. 1B is a plan view showing an electrode pattern provided on the piezoelectric element 104 constituting the vibration type actuator 100. FIG. 1C is a perspective view for explaining the first vibration mode excited by the vibrating body 105 constituting the vibration type actuator 100. FIG. 1D is a perspective view for explaining a second vibration mode excited by the vibrating body 105 constituting the vibration type actuator 100.

  The vibration type actuator 100 includes a driven body 101 and a vibration body 105, and the vibration body 105 includes two protrusions 102, an elastic body 103, and a piezoelectric element 104. The two protrusions 102 and the elastic body 103 are made of a metal material such as stainless steel, for example. The two protrusions 102 provided on one surface of the elastic body 103 may be integrally formed with the elastic body 103 by machining or the like of a plate material constituting the elastic body 103, or by joining such as welding. It may be attached to the elastic body 103. The driven body 101 and the two protrusions 102 are in pressure contact with each other in the illustrated Z direction by a pressing means (not illustrated).

  The piezoelectric element 104 that is an electro-mechanical energy conversion element has an electrode region that is divided into two equal parts in the longitudinal direction, and the polarization direction in each electrode region is the same direction (+). For example, by applying the AC voltage VB to the electrode region located on the right side of the two electrode regions of the piezoelectric element 104 and applying the AC voltage VA to the electrode region located on the left side, FIG. Vibrations in two vibration modes shown in d) can be generated.

  The first vibration mode in FIG. 1C is a primary out-of-plane bending vibration mode in which two nodal lines appear in the vibrating body 105 in parallel with the X direction, which is a direction connecting the two protrusions 102. The second vibration mode shown in FIG. 1D is applied to the vibrating body 105 in parallel with the Y direction perpendicular to both the X direction connecting the two protrusions 102 and the Z direction which is the plate thickness direction of the elastic body 103. This is a secondary out-of-plane bending vibration mode in which three nodal lines appear.

  The two protrusions 102 are arranged in the vicinity of a position that becomes an antinode of vibration in the vibration of the first vibration mode and in the vicinity of a position that becomes a vibration node in the vibration of the second vibration mode. Therefore, the tip surfaces of the two protrusions 102 are reciprocated in the X direction by performing a pendulum motion around the vibration node of the second vibration mode, and reciprocated in the Z direction by the vibration of the first vibration mode. Can exercise. That is, by exciting and superimposing the first vibration mode and the second vibration mode so that the vibration phase difference is in the vicinity of ± π / 2, the XZ plane is formed on each tip surface of the two protrusions 102. Elliptical motion can be generated in the interior.

  Since a frictional force due to pressure contact acts between the two protrusions 102 and the driven body 101, the driven body 101 and the vibrating body 105 are relatively moved by the elliptical motion of the two protrusions 102. A friction driving force that moves in the X direction can be generated. The generation ratio of the first vibration mode and the second vibration mode can be changed by changing the phase difference between the AC voltages VA and VB applied to the two electrode regions of the piezoelectric element 104, and thus driven The relative moving speed of the body 101 and the vibrating body 105 can be adjusted.

  FIG. 2 is a perspective view showing a schematic configuration of a lens driving mechanism 200 to which the vibration type actuator 100 is applied. The lens driving mechanism 200 includes a vibrating body 201, a lens holding member 202, a first guide bar 203, a second guide bar 204, a pressure magnet 205, and a lens 206. The vibrating body 201 corresponds to the vibrating body 105 described with reference to FIG. 1, and the second guide bar 204 corresponds to the driven body 101 described with reference to FIG.

  The first guide bar 203 and the second guide bar 204 are held by a base (not shown) so as to be parallel to each other. The lens holding member 202 includes a cylindrical holder portion 202a that holds the lens 206, a holding portion 202b that holds the vibrating body 201 and the pressing magnet 205, and a guide portion 202c through which the first guide bar 203 is inserted. The guide part 202c is movably inserted into the first guide bar 203 to form the first guide part.

  A magnetic circuit is formed between the pressing magnet 205, which is a permanent magnet, and the second guide bar 204, and an attractive force is generated between these members, whereby the pressing magnet 205 and the second guide bar 204 are Is pressed against the second guide bar 204. As a result, the two protrusions (corresponding to the protrusions 102 of the vibrating body 105 in FIG. 1) of the vibrating body come into pressure contact with the second guide bar 204 to form the second guide section.

  In addition, since the second guide portion forms a guide mechanism using magnetic attraction force, the vibrating body 201 and the second guide bar 204 are separated when receiving an external force or the like. It is expected that. As a countermeasure, in the lens driving mechanism 200, the lens holding member 202 (vibrating body 201) returns to a predetermined position when the drop-off prevention unit 202 d provided on the lens holding member 202 comes into contact with the second guide bar 204. It is configured.

  By supplying a predetermined AC voltage to the vibrating body 201, as described with reference to FIG. 1, a frictional driving force is generated between the vibrating body 201 and the second guide bar 204, and this frictional driving force causes the lens to move. The holding member 202 is driven. Here, the lens driving mechanism 200 in which the vibrating body 201 moves in the optical axis direction together with the lens holding member 202 is taken up. However, the lens driving mechanism has a holding member that holds the lens with respect to the fixed vibrating body. The driving body may be configured to move in the optical axis direction.

<First Embodiment>
FIG. 3 is a diagram showing a circuit configuration of a drive device 300 that drives the vibration type actuator 100 and constitutes the control device according to the first embodiment of the present invention. The driving device 300 includes a pulse signal generation circuit 301 and a booster circuit 302.

  The pulse signal generation circuit 301 generates a voltage signal based on, for example, an output from a control circuit 402 (see FIG. 4) described later. Specifically, the pulse signal generation circuit 301 includes a pulse signal A1 for operating the vibrating body 105 at a frequency that is approximately 1/3 of the resonance frequency, and a pulse having a phase difference of 180 degrees with respect to the pulse signal A1. An oscillator that outputs the signal A2 is included. The pulse signal generation circuit 301 is connected to a DC-DC converter circuit (not shown) that supplies a DC power supply, and the switching element is turned on / off by the pulse signals A1 and A2 to output a voltage signal. Circuit (H bridge circuit).

  In the present embodiment, it is assumed that the pulse signals A1 and A2 are rectangular waves. The pulse duty of the pulse signals A1 and A2 is adjusted so as to obtain a desired voltage value by well-known PWM (pulse width modulation) control, and at that time, as described later, the third harmonic is set to a large value. Is done.

  The voltage signal generated by the switching circuit is sent to the booster circuit 302 as an output from the pulse signal generation circuit 301. In the following description, the frequency of the voltage signal output from the pulse signal generation circuit 301 is referred to as “drive frequency”.

  The booster circuit 302 includes a coil 304 and a transformer 305, and boosts the voltage signal input from the pulse signal generation circuit 301 to a predetermined voltage value. In the booster circuit 302, the input voltage signal is converted from a rectangle to a sine waveform by the filter effect of the booster circuit 302, and applied as a drive signal to the piezoelectric element 104 included in the vibrating body 105. In the present embodiment, as will be described later, the electrical resonance frequency of the booster circuit 302 is adjusted so that the voltage gain of the third harmonic is larger than the voltage gain of the fundamental wave.

  Here, an equivalent circuit of the piezoelectric element 104 will be described. An equivalent circuit of the piezoelectric element 104 is configured by an RLC series circuit of a mechanical vibration portion of the vibrating body 105 and a capacitor 306 as an intrinsic capacitance Cd of the piezoelectric element 104 connected in parallel to the RLC series circuit. . The RLC series circuit includes an equivalent coil 307 having a self-inductance Lm, an equivalent capacitor 308 having a capacitance Cm, and an equivalent resistor 309 having a resistance value Rm.

  FIG. 4 is a block diagram showing the configuration of the control device 400 according to the first embodiment of the present invention of the vibration type actuator 100 having the driving device 300. The control device 400 includes a command value generation unit 401, a control circuit 402, a driving device 300, and a position detection unit 407. The control circuit 402 includes a feedback calculation unit 409, a phase difference conversion unit 411, a frequency conversion unit 412, a phase difference / frequency determination unit 413, and a voltage adjustment unit 414. The drive device 300 includes the pulse signal generation circuit 301 and the booster circuit 302 as described above.

  The command value generation unit 401 generates a command value for each relative position of the driven body 101 and the vibrating body 105. Further, the position detection unit 407 obtains a relative position 408 between the driven body 101 and the vibrating body 105 based on a detection signal from an encoder (position sensor) (not shown) provided in the vibration type actuator 100. A difference between the command value generated by the command value generation unit 401 and the relative position 408 output from the position detection unit 407 is calculated as a position deviation 415 and input to the feedback calculation unit 409.

  For example, a PID computing unit or the like is used as the feedback computing unit 409, but is not limited thereto. The feedback calculation unit 409 calculates the control amount 410 based on the position deviation 415, for example, by PID calculation or the like. The control amount 410 is input to the phase difference conversion unit 411 and the frequency conversion unit 412.

  By the phase difference conversion unit 411 and the frequency conversion unit 412, the control amount 410 is converted into a phase difference control amount and a frequency control amount that are control parameters for driving the vibration type actuator 100. The phase difference control amount output from the phase difference conversion unit 411 and the frequency control amount output from the frequency conversion unit 412 are input to the phase difference / frequency determination unit 413. The phase difference / frequency determination unit 413 generates a control signal from the phase difference control amount and the frequency control amount, and inputs the control signal to the pulse signal generation circuit 301 of the driving device 300.

  The reference frequency of the frequency converter 412 is set to about １ ／ of the resonance frequency of the vibrating body 105. Thereby, as will be described later, the drive frequency is set to about ３ of the resonance frequency of the vibrating body 105.

  Since the operation of the driving device 300 has already been described with reference to FIG. 3, only a brief description will be given here. The pulse signal generation circuit 301 generates pulse signals A1 and A2 having different phases based on the phase difference and frequency included in the input control signal and the pulse width information input from the voltage adjustment unit 414. An output (voltage signal) based on the pulse signals A1 and A2 from the pulse signal generation circuit 301 is boosted to a predetermined voltage value by the booster circuit 302 and applied to the piezoelectric element 104 included in the vibrating body 105. The relative movement amount of the vibrating body 105 and the driven body 101 due to the vibration excited by the vibrating body 105 is detected by an encoder (not shown) and input to the position detection unit 407 as described above. Thus, the control device 400 performs feedback control of the vibration type actuator 100.

  In the present embodiment, the control device 400 will be described as performing two-phase driving in which the piezoelectric element 104 is driven in two phases. However, the control device 400 can be applied to a vibration type actuator that can be driven by a drive signal of two or more phases.

  Next, the control circuit 402 will be described in detail. FIG. 5 is a diagram illustrating an output (control amount) from the phase difference / frequency determination unit 413. FIG. 5A shows the output of the phase difference and the frequency based on the control amount. The horizontal axis represents the control amount, the vertical axis represents the phase difference, and the vertical axis represents the frequency. Yes.

  The phase difference / frequency determination unit 413 performs control so that the phase difference is changed using the region where the absolute value of the control amount is small as the phase difference control region, and the frequency is changed using the region where the absolute value of the control amount is large as the frequency control region. The control by phase difference or frequency is switched according to the amount.

  In the phase difference control region, the frequency is fixed to the frequency upper limit value, and the phase difference is changed between the phase difference upper limit value and the lower limit value, thereby controlling the reversal and stop of the driving direction and the speed in the low speed region. At this time, as described later, since the drive frequency is set to about 約 of the resonance frequency of the vibrating body 105, the phase difference upper limit value and the phase difference lower limit value need to be about 約 as well. For example, when the control range of the phase difference when the vibrating body 105 is driven near the resonance frequency is +120 degrees to −120 degrees, the phase difference / frequency determination unit 413 sets the control range of the phase difference to +40 degrees to Set to -40 degrees.

  In the frequency control region, the phase difference is fixed to the phase difference lower limit value or the phase difference upper limit value, and the frequency is changed between the frequency upper limit value and the frequency lower limit value (for example, 92 kHz to 89 kHz). Control the speed.

  FIG. 5B is a diagram illustrating the driving speed of the vibration type actuator 100 (the moving speed of the driven body 101) based on the control amount of FIG. In FIG. 5B, the control amount is taken on the horizontal axis and the drive speed is taken on the vertical axis, and the elliptical motion shown in the lower stage schematically shows the movement of the tip of the protrusion 102. The driving speed of −300 to +300 mm / s is an example, and the relative moving speed of the driven body 101 and the vibrating body 105 in the vibration type actuator 100 is not limited to this range. Further, the positive / negative of the driving speed indicates that the driving direction is the reverse direction.

  Phase difference control is performed in a low-speed drive region where the drive speed is −50 to +50 mm / s, and frequency control is performed in other high-speed drive regions. In the phase difference control, the elliptical motion of the protrusion 102 is controlled so that the ellipticity ratio (ellipse aspect ratio) changes, and the direction of the elliptical motion changes by reversing the sign of the phase difference. And in the vertically long shape in which the ellipticity ratio is 0 (zero), the driving speed is 0 (zero). On the other hand, in the frequency control, the driving speed is controlled by changing the ellipse amplitude while the ellipticity ratio of the elliptical motion is kept constant. By these controls, the phase difference and the frequency are set so that the driving speed is as linear as possible with respect to the control amount.

  FIG. 6 is a diagram illustrating the electrical resonance frequency of the booster circuit 302 and the frequency characteristics of the drive signal output from the booster circuit 302, and is a diagram for explaining the voltage amplification factor by the booster circuit 302. 6A to 6C show changes in the electrical resonance frequency fe of the booster circuit 302 when the circuit constants of the coil 304 and the transformer 305 are changed in the booster circuit 302, respectively. The electric resonance frequency fe is determined by the values of the coil 304, the transformer 305, and the capacitor 306 that is the specific capacitance of the piezoelectric element 104.

  Here, the configuration of the booster circuit 302 is determined on the assumption that the drive frequency fp (the frequency of the voltage signal output from the pulse signal generation circuit 301) is 30 kHz and the resonance frequency fm of the vibrating body 105 is 86 kHz.

  FIG. 6A shows an example in which the primary winding coil of the transformer 305 is 30 μH, the secondary winding coil is 7.68 mH, and the coil 304 is 0 μH when the capacitor 306 is 0.54 nF. The electric resonance frequency fe is 277 kHz. In this case, the relationship of fm / 3 ≦ fp ≦ fe / 3 is established. When this relationship is satisfied, the vibrating body 105 can be driven at a frequency that is approximately 1/3 of the resonance frequency of the vibrating body 105, and the voltage amplification factor of the third harmonic (90 kHz) by the booster circuit 302 is increased. Can be made larger than the voltage amplification factor of the fundamental wave (30 kHz). Therefore, it is possible to efficiently drive the vibrating body 105 using the third harmonic.

  FIG. 6B shows an example in which the electrical resonance frequency fe is shifted from 277 kHz to the low frequency side. Here, the circuit constants of the transformer 305 and the capacitor 306 are the same as in FIG. 6A, and the electric resonance frequency fe is shifted to 133 kHz by changing the coil 304 to 10 μH. In this case, not only the relationship of fm / 3 ≦ fp ≦ fe / 3 is satisfied, but also the relationship of 2fp ≦ fm ≦ 3fp and 2fp ≦ fe is established.

  Driving efficiency can be increased by using more third-order harmonics than the fundamental wave of the driving frequency fp. Therefore, here, the electrical resonance frequency fe is adjusted so that the voltage of 3 fp is larger than the voltage at 2 fp, with 2 fp being the center of the fundamental wave and the third harmonic. When the condition of FIG. 6B is satisfied, the vibrator 105 using the third harmonic can be driven with higher efficiency than when the condition of FIG. 6A is satisfied. It becomes.

  FIG. 6C shows an example (reference example) in which the electrical resonance frequency fe is further shifted from 133 kHz to the lower frequency side. Here, the circuit constant of the transformer 305 is the same as that in FIG. 6A, and the electrical resonance frequency fe is shifted to 60 kHz by changing the coil 304 to 10 μH and the capacitor 306 to 3.0 nF. In this case, the condition (fm / 3 ≦ fp ≦ fe / 3) established in FIGS. 6A and 6B is not satisfied, and fe / 3 <fm / 3 <fp. In this case, since the voltage gain of the third harmonic is smaller than the voltage gain of the fundamental wave, the driving efficiency of the vibrating body 105 is lowered.

  FIG. 7A is a diagram showing the relationship between the pulse width Tw of the pulse signals A1 and A2, and the fundamental wave and the third harmonic in the drive signal output from the booster circuit 302. FIG. The pulse duty Tw / T, which is the ratio of the pulse width Tw to the period T of the pulse signals A1, A2, is set to 17%, for example. As a result, the drive signal output from the booster circuit 302 has a third harmonic higher than the fundamental wave, which is one of the features of this embodiment.

  FIG. 7B is a diagram showing the result of calculating the voltage ratios of the fundamental wave and the third harmonic with respect to the pulse signals A1 and A2 pulse duty Tw / T of the drive signal output from the booster circuit 302. . The voltage ratio of the fundamental wave is a value obtained by dividing the voltage value (Vp-p) of the fundamental wave at each pulse duty Tw / T by the voltage value (Vp-p) of the fundamental wave with a pulse duty Tw / T of 50%. is there. Therefore, the voltage ratio of the fundamental wave becomes 1 when the pulse duty Tw / T is 50%. The voltage ratio of the third harmonic is the voltage value (Vp-p) of the third harmonic at each pulse duty Tw / T, and the voltage value (Vp-p) of the fundamental wave with a pulse duty Tw / T of 50%. The value divided by p).

  Conventionally, when the vibration actuator 100 is driven, the fundamental wave is increased and the third harmonic is reduced as much as possible. However, in order to efficiently drive the vibration type actuator 100 using the third harmonic, it is desirable to make the fundamental wave as small as possible and increase the third harmonic, and 0% <Tw / T <33%. It can be seen that this range meets this condition. The theoretical optimum value is 17% where the voltage ratio of the third harmonic is the maximum and the fundamental wave is small, but considering the experimental results described below, the pulse duty Tw / T is 10 to 20%. It is desirable to set the range.

  FIG. 8 is a diagram illustrating measurement results of drive speed and power supply power when the vibration type actuator 100 is driven by the control device 400. The vibration type actuator 100 is installed under certain conditions regardless of the pulse duty Tw / T. In FIG. 8, the driving frequency fp is set to 30 kHz, the phase difference between the pulse signals A1 and A2 is set to 33 degrees, and the driven body 101 is driven when the pulse duty Tw / T is changed in the range of 10 to 40%. The result of measuring the speed is shown.

  In the conventional driving method of the vibration type actuator 100, the speed is generally the highest when the pulse duty Tw / T is 50%. On the other hand, in this embodiment, the speed is highest when the pulse duty Tw / T is 17%, and the power supply power is lowest when the pulse duty Tw / T is 13%. This is because the drive frequency fp is approximately 1/3 of the conventional frequency (1/3 of the resonance frequency fm of the vibrating body 105), and the third harmonic is used for driving. From the measurement results shown in FIG. 8, it can be seen that the vibration actuator 100 can be driven with the highest efficiency when the pulse duty Tw / T is in the vicinity of 15%. On the other hand, from the viewpoint of power supply power, the power supply power is small when the pulse duty Tw / T is in the range of 10% to 20%. From these facts, it can be determined that by setting the pulse duty Tw / T in the range of 10% to 20%, it is possible to drive with good balance in consideration of the driving speed and the power supply power.

  FIG. 9A is a diagram showing a breakdown of power supply power in a conventional driving device, where the driving frequency fp is set to 90 kHz, the phase difference between the two-phase pulse signals is set to 110 degrees, and the pulse duty Tw / T is set to 50%. Has been. On the other hand, FIG. 9B is a diagram showing a breakdown of power supply power in the driving apparatus 300, and the booster circuit 302 includes a circuit (drive frequency fp: 30 kHz) having the characteristics shown in FIG. Phase difference: 33 degrees, pulse duty Tw / T: 15%). 9A and 9B show the results of calculating the breakdown of each loss with respect to the power supply power when the drive speed of the driven body 101 of the vibration type actuator 100 is 150 mm / s.

  In common with FIGS. 9A and 9B, the switch loss is a loss generated when the switching element of the switching circuit constituting the pulse signal generation circuit is turned on / off. The coil loss is a heat loss caused by the resistance of the coil of the booster circuit. The on-resistance loss is a heat loss caused by the on-resistance of the switching element of the switching circuit constituting the pulse signal generation circuit. The transformer loss is a heat loss caused by each resistance of the secondary winding coil and the primary winding coil of the transformer constituting the booster circuit. These are the circuit losses of the drive device, the switch loss increases as the drive frequency fp increases, and the heat loss increases as the drive current increases. The motor loss is the total value of the internal loss and the sliding loss of the vibration type actuator 100.

  Comparing each loss of FIGS. 9A and 9B, it can be seen that in the driving device 300, the switch loss and the transformer loss are smaller than in the conventional driving device. The reduction in switch loss is due to the drive frequency fp being 1/3. Further, the transformer loss is reduced because the drive current is reduced. This is because, in the conventional drive device with a drive frequency fp of 90 kHz, the high-frequency side current (current close to the electric resonance frequency 277 kHz of the booster circuit) increases, whereas the drive device 300 with the drive frequency fp of 30 kHz. This is because unnecessary current on the high frequency side can be suppressed. 9A and 9B, it can be seen that the drive device 300 can obtain the same drive characteristics as those obtained by the conventional drive device with a smaller electric power than the conventional drive device.

  As described above, since the driving apparatus 300 according to the present embodiment can reduce the frequency of the pulse signals A1 and A2 generated by the pulse signal generation circuit 301 as compared with the conventional one, the cost of the pulse signal generation circuit 301 can be reduced. And miniaturization becomes possible. Further, the power supply power when the vibration type actuator 100 is driven under the condition that the same driving speed as the conventional one can be obtained can be reduced. Therefore, for example, when the driving device 300 is applied to the lens driving mechanism 200 of the imaging device, it is possible to obtain driving characteristics equivalent to the conventional one with low power consumption, and to reduce the power consumption of the battery used as the power source of the imaging device. Can be suppressed.

  In the present embodiment, the drive frequency fp is set to about ３ of the resonance frequency fm of the vibrating body 105 by setting the reference frequency of the frequency converter 412 to about １ ／ of the resonance frequency fm of the vibrating body 105. However, the present invention is not limited to this. For example, the pulse signal generation circuit 301 may incorporate a configuration in which the drive frequency fp is about 約 of the resonance frequency fm of the vibrating body 105.

Second Embodiment
In the second embodiment, a driving device in which the function of a high-pass filter is added to the driving device 300 described in the first embodiment will be described.

  FIG. 10A is a diagram showing a circuit configuration of a drive device 300A that constitutes the control device according to the second embodiment of the present invention. Of the driving device 300A, the same elements as those of the driving device 300 shown in FIG. The driving device 300A includes a pulse signal generation circuit 301 and a booster circuit 302A.

  The booster circuit 302A functions as a high-pass filter that reduces the fundamental voltage of the drive frequency fp. In other words, the booster circuit 302A includes a coil 304, a transformer 305, and a capacitor 1001, and can adjust the cutoff frequency of the high-pass filter by adjusting the capacitance of the capacitor 1001. For example, when the drive frequency fp is 30 kHz and the resonance frequency fm of the vibrating body 105 is 86 kHz, the cut-off frequency is set to 55 kHz in order to reduce the voltage of the drive frequency fp. For that purpose, if the primary winding coil of the transformer 305 is 30 μH, the secondary winding coil is 7.68 mH, the coil 304 is 10 μH, and the capacitor 306 of the piezoelectric element 104 is 0.54 nF, the capacitor 1001 is set to 150 nF. That's fine.

  FIG. 10B is a diagram illustrating the frequency characteristics of the drive signal output from the booster circuit 302A. Although the voltage of the fundamental wave with a driving frequency fp of 30 kHz is low, the voltage of 90 kHz, which is the third harmonic, is increased, and thus the vibration actuator 100 can be driven with higher efficiency. Recognize. The electrical resonance frequency fe of the booster circuit 302A at this time is 170 kHz, and the relationship of fm / 3 ≦ fp ≦ fe / 3 is satisfied, and 2fp ≦ fm ≦ 3fp and 2fp ≦ fe, The relationship is also satisfied.

  The maximum driving speed of the driven body 101 when the vibration type actuator 100 is driven by the control device 400 (see FIG. 4) including the driving device 300 (see FIG. 3) is 300 mm / s. It was 0.4 W (see FIG. 8). Under the same conditions (pulse duty Tw / T: 15%, phase difference between pulse signals A1 and A2: 33 degrees), the maximum drive speed when the vibration type actuator 100 is driven by the control device including the drive device 300A is 330 mm. / S. Further, the power supply power at this time was 0.31 W. Therefore, the drive efficiency of the vibration type actuator 100 can be further increased to save power, and the drive performance can be improved.

<Third Embodiment>
In the third embodiment, an example in which the driving device described in the first embodiment or the driving device 300A described in the second embodiment is applied to a dust removing device of an optical device will be described. FIG. 11A is a perspective view illustrating a schematic configuration of the imaging apparatus main body 1100, in which a lens barrel (photographing lens) is removed. Inside the imaging apparatus main body 1100 is provided a mirror box 1102 for guiding a photographic light beam that has passed through a photographic lens (not shown), and a main mirror (quick return mirror) 1103 is provided in the mirror box 1102. .

  FIG. 10B is a perspective view illustrating a schematic configuration of the imaging unit 1110 of the camera body 1101 equipped with the dust removing device. The imaging unit 1110 is disposed on the photographing optical axis at a position where a light beam that has passed through a photographing lens (not shown) and the mirror box 1102 forms an optical image (subject image).

  The imaging unit 1110 includes an imaging element 1104 that is a photoelectric conversion element such as a CCD sensor or a CMOS sensor that converts an optical image into an electrical signal. A vibrating body 1105 is attached to the imaging element 1104 so that the space on the subject side (imaging surface) of the imaging element 1104 is sealed. The vibrating body 1105 includes an optical member 1106 having a rectangular plate shape, which is an elastic body, and a pair of piezoelectric elements 1107a and 1107b bonded to the longitudinal ends of the optical member 1106. The optical member 1106 is composed of an optical member having a high transmittance such as a cover glass, an infrared cut filter, or an optical low-pass filter, and light transmitted through the optical member 1106 enters the image sensor 1104.

  The piezoelectric elements 1107a and 1107b have the same configuration as that of the piezoelectric element 104 described with reference to FIG. By applying a drive signal having a drive frequency fp to the piezoelectric elements 1107a and 1107b, the vibration body 1105 is excited to vibrate, and dust attached to the optical member 1106 is removed from the optical member 1106.

  A driving device 1120 is connected to each electrode of the piezoelectric elements 1107a and 1107b. Here, for the sake of convenience, two drive devices 1120 are shown, but a drive signal can be applied from one drive device 1120 to the piezoelectric elements 1107a and 1107b. The driving device 1120 includes a pulse signal generation circuit 301 and a booster circuit 302B. Since the configuration of the pulse signal generation circuit 301 is as described with reference to FIG. 3, the description thereof is omitted here. Here, the pulse signal generation circuit 301 outputs a two-phase pulse signal having a drive frequency fp of 40 kHz and a pulse duty of 15% to the booster circuit 302B.

  Here, the booster circuit 302B is composed only of a coil having an inductance of 68 μH. The resonance frequency fm of the vibrating body 1105 is 110 kHz, and the capacitances of the piezoelectric elements 1107a and 1107b are each 10.78 nF. In this case, the electrical resonance frequency fe due to the capacitance of the coil of the booster circuit 302B and the piezoelectric elements 1107a and 1107b is 186 kHz. Therefore, the relationship of fm / 3 ≦ fp ≦ fe / 3 is satisfied, and the relationship of 2fp ≦ fm ≦ 3fp and 2fp ≦ fe is also satisfied.

  Therefore, since the vibrator 1105 having a resonance frequency higher than the drive frequency that can be generated by the pulse signal generation circuit 301 can be driven efficiently, the cost and size of the pulse signal generation circuit 301 can be reduced and the circuit loss can be reduced. Electricity can be realized.

<Other embodiments>
Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. Furthermore, each embodiment mentioned above shows only one embodiment of this invention, and it is also possible to combine each embodiment suitably.

  For example, in the first embodiment, the example in which the lens for autofocus is driven by the control device 400 including the drive device 300 according to the present invention has been described. However, the present invention is not limited to this. It can be used for the purpose of driving the lens. The drive device according to the present invention is a drive of a vibration type actuator (vibrating body) that performs image blur correction due to camera shake or the like by moving a lens or an image sensor in a plane substantially orthogonal to the optical axis direction. Can also be used.

DESCRIPTION OF SYMBOLS 100 Vibration type actuator 101 Driven body 102 Protruding part 103 Elastic body 104 Piezoelectric element 105, 201 Vibration body 200 Lens drive mechanism 300, 300A Drive device 301 Pulse signal generation circuit 302 Booster circuit 304 Coil 305 Transformer 306 Capacitor 400 Control device

Claims (10)

Control for exciting a predetermined vibration by applying an alternating voltage to the electro-mechanical energy conversion element to a vibration body having an electro-mechanical energy conversion element and an elastic body joined to the electro-mechanical energy conversion element A device,
The control device includes:
Generating means for generating a pulse signal for driving the vibrator with a third harmonic;
Boosting means for amplifying the pulse signal generated by the generating means to generate the alternating voltage,
When the resonance frequency of the vibrating body is fm, the frequency of the pulse signal is fp, and the electric resonance frequency generated by the boosting means and the electromechanical energy conversion element is fe, fm / 3 ≦ fp ≦ fe / 3, The control apparatus characterized by satisfying the following conditions.   2. The control device according to claim 1, wherein conditions of 2fp ≦ fm ≦ 3fp and 2fp ≦ fe are satisfied.   The pulse duty Tw / T of the pulse signal when the pulse width of the pulse signal is Tw and the period is T satisfies the relationship of 0% <Tw / T <33%. 2. The control device according to 2.   4. The control device according to claim 3, wherein the pulse duty Tw / T satisfies a relationship of 10% <Tw / T <20%.   The control device according to claim 1, wherein the boosting unit includes a filter that reduces a voltage having a frequency of the pulse signal. A vibration-type actuator comprising: an oscillating body having an electro-mechanical energy conversion element; an elastic body joined to the electro-mechanical energy conversion element; and a driven body in pressure contact with the elastic body;
A control device according to any one of claims 1 to 5, which controls driving of the vibration actuator.
A vibration type driving device that relatively moves the vibrating body and the driven body by vibration excited on the vibrating body by an alternating voltage applied to the electro-mechanical energy conversion element by the control device;
The control device includes:
Detecting means for detecting a relative position between the vibrating body and the driven body;
Setting means for setting the control amount of the frequency and phase difference of the AC voltage based on the relative position;
The vibration-type drive device, wherein the generating unit and the boosting unit generate the AC voltage based on the frequency and phase difference set by the setting unit. A vibrator having an electro-mechanical energy conversion element and an elastic body joined to the electro-mechanical energy conversion element;
A control device according to any one of claims 1 to 5, which controls driving of the vibrating body,
A dust removing device that removes dust attached to the elastic body by vibration generated by applying an alternating voltage to the electro-mechanical energy conversion element by the control device and excited by the vibrating body;
The control device includes:
Further comprising setting means for setting a control amount of the frequency and phase difference of the AC voltage;
The dust removing device, wherein the generating unit and the boosting unit generate the AC voltage based on a frequency and a phase difference set by the setting unit. An image sensor;
An oscillating body having an optical member attached to the imaging surface of the imaging element, and an electro-mechanical energy conversion element provided on the optical member,
A control device according to any one of claims 1 to 5, which controls driving of the vibrating body,
An imaging device that removes dust attached to the optical member by vibration generated by applying an alternating voltage to the electromechanical energy conversion element by the control device and exciting the vibrating body,
The control device includes:
Further comprising setting means for setting a control amount of the frequency and phase difference of the AC voltage;
The imaging device, wherein the generating unit and the boosting unit generate the AC voltage based on the frequency and phase difference set by the setting unit. A vibration-type actuator comprising: an oscillating body having an electro-mechanical energy conversion element; an elastic body joined to the electro-mechanical energy conversion element; and a driven body in pressure contact with the elastic body;
A holding member that holds the lens and is attached to the vibrating body or the driven body and moves in the optical axis direction by relative movement of the vibrating body and the driven body;
A control device according to any one of claims 1 to 5, which controls driving of the vibration actuator.
A lens barrel that relatively moves the vibrating body and the driven body by vibration excited on the vibrating body by an alternating voltage applied to the electro-mechanical energy conversion element by the control device;
The control device includes:
Detecting means for detecting the position of the holding member in the optical axis direction;
Setting means for setting the control amount of the frequency and the phase difference of the AC voltage based on the position of the holding member in the optical axis direction;
The lens barrel according to claim 1, wherein the generating unit and the boosting unit generate the AC voltage based on the frequency and phase difference set by the setting unit. A lens barrel having a holding member that holds the lens, and a vibration-type actuator that drives the holding member in the optical axis direction;
The control device according to any one of claims 1 to 5, which controls driving of the vibration type actuator;
An image pickup device that photoelectrically converts an optical image formed by the light flux that has passed through the lens barrel,
The vibration type actuator is
An oscillating body having an electro-mechanical energy conversion element and an elastic body joined to the electro-mechanical energy conversion element;
A driven body in pressure contact with the elastic body,
The holding member is attached to the vibrating body or the driven body, and the vibrating body and the driven body are caused by vibration excited by the vibrating body by an AC voltage applied to the electromechanical energy conversion element by the control device. Move in the direction of the optical axis according to the movement relative to the body,
The control device includes:
Detecting means for detecting the position of the holding member in the optical axis direction;
Setting means for setting the control amount of the frequency and the phase difference of the AC voltage based on the position of the holding member in the optical axis direction;
The imaging device, wherein the generating unit and the boosting unit generate the AC voltage based on the frequency and phase difference set by the setting unit.

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