JP5940184B2 - Vibration body drive circuit, device, and optical apparatus - Google Patents

Description

  The present invention relates to a driving circuit for a vibrating body.

  2. Description of the Related Art In recent years, with an imaging apparatus as an optical device, dust attached to an optical system during use has an effect on a captured image as the resolution of an imaging element improves. In particular, the resolution of image sensors used in video cameras and still cameras is remarkably improved. For this reason, dust (powder) such as dust from the outside and abrasion powder generated on the internal mechanical rubbing surface is applied to optical members such as an infrared cut filter and an optical low-pass filter disposed near the image sensor. When adhered, there is little blurring of the image on the surface of the image sensor, so that powder may be reflected in the photographed image.

  In addition, an image pickup unit such as a copying machine or a facsimile machine as an optical device scans a line sensor or scans a document close to the line sensor, thereby reading a flat document. Yes. In this case, if dust adheres to the light incident portion on the line sensor, it will appear in the scanned image. In a reading unit of a facsimile machine that scans and reads a document, or a reading unit of a so-called flow-reading type copying machine that reads a document from an automatic document feeder during conveyance, a single dust continues in the document feeding direction. The image was captured as a line image, and the image quality was greatly impaired.

  Patent Document 1 proposes a dust removing device capable of moving such dust in a desired direction by exciting a traveling wave in a vibrating body provided with an optical member. FIG. 3 is a schematic diagram showing the configuration of the dust removing device disclosed in Patent Document 1. As shown in FIG. A vibrating body 501 including an optical member 502 is provided on the light incident side of the image sensor 503. The piezoelectric elements 101a and 101b, which are electro-mechanical energy conversion elements, are arranged with their positions shifted in the direction in which the nodal lines of out-of-plane bending vibration in the vibrating body 501 are arranged. An alternating voltage having the same frequency and a phase difference of 90 ° is applied to the piezoelectric elements 101a and 101b.

  The frequency of the applied alternating voltage is between the resonance frequency of the m-th order vibration mode (m is a natural number) deformed out of plane along the longitudinal direction of the vibrating body 501 and the resonance frequency of the (m + 1) -th order vibration mode. Frequency. The vibrating body 501 has a vibration of an mth-order vibration mode having a response of a resonance phenomenon and a time phase difference of 90 ° (a phase advanced by 90 ° with respect to an m-th order out-of-plane bending vibration) ( m + 1) The vibration of the next vibration mode is excited with the same amplitude and the same vibration period. The vibration body 501 generates a combined vibration (traveling wave) in which the vibrations of the two vibration modes are combined. Due to this combined vibration, the dust on the surface of the vibrating body 501 is moved in a desired direction.

JP 2008-207170 A

However, in the conventional dust removing device, the change in the amplitude of the alternating voltage applied to the piezoelectric element 101, that is, the gradient in the frequency characteristics of the alternating voltage increases in the vicinity of the resonance frequency of the vibrating body 501 in the frequency band to be used. For this reason, when the resonance frequency of the vibrating body 501 varies due to individual differences, or when the resonance frequency changes due to heat generation or the like during driving, the alternating voltage greatly fluctuates. When the alternating voltage becomes larger than necessary, the power consumption increases due to an increase in current, and the optical member 501 is damaged due to an increase in vibration amplitude excited by the vibrating body 501. Further, when the alternating voltage is lower than the required voltage, the vibration amplitude of the out-of-plane bending vibration excited by the vibrating body 501 cannot be sufficiently obtained, and the dust removal efficiency is lowered. Further, when the harmonic component of the drive frequency fd is superimposed on the fundamental wave, the waveform of the drive alternating voltage may be distorted. When the waveform distortion is large, unnecessary vibration is excited in the vibrating body .

According to one aspect of the present invention, even when the resonance frequency of the vibrator varies in the frequency band to be used or changes during driving, the fluctuation of the alternating voltage applied to the electromechanical energy conversion element is small and a stable voltage. The present invention relates to a drive circuit or device that outputs an amplitude . Another embodiment of the present invention relates to a driving circuit or device in which the superposition of the harmonic component of the driving frequency on the fundamental wave is reduced in the alternating voltage for driving.

According to one embodiment of the present invention, an elastic body, a vibrating body including a first electro-mechanical energy conversion element fixed to the elastic body, and a second electro-mechanical energy conversion element, and a drive circuit are provided. Have
The drive circuit includes a first inductor and a first capacitor connected in series to the first electro-mechanical energy conversion element, and a second connected in series to the second electro-mechanical energy conversion element. An inductor and a second capacitor,
The first and second electro-mechanical energy conversion elements respectively generate alternating voltages that generate vibrations in which the vibrations of the first vibration mode and the second vibration mode having different orders are superimposed on the vibrating body. The alternating voltage applied to the first electro-mechanical energy conversion element and the second electro-mechanical energy conversion element respectively has a different phase and the same frequency, and the first inductor When the series resonance frequency by the first capacitor and the first capacitor is fs1, the series resonance frequency by the second inductor and the second capacitor is fs2, and the resonance frequency of the vibrating body is fm, 0.73 The present invention relates to an apparatus characterized by satisfying fm <fs1 <1.2 · fm and 0.73 · fm <fs2 <1.2 · fm.
Another embodiment of the present invention includes a vibrating body including an elastic body, a first electro-mechanical energy conversion element fixed to the elastic body, and a second electro-mechanical energy conversion element, and a drive circuit. ,
Have
The drive circuit is
A first inductor and a first capacitor connected in series to the first electro-mechanical energy conversion element; a second inductor connected in series to the second electro-mechanical energy conversion element; And a capacitor
A first vibration mode vibration and a second vibration mode vibration having different orders are generated in the vibration body by switching over time, and a series resonance frequency by the first inductor and the first capacitor is fs1. When the series resonance frequency of the second inductor and the second capacitor is fs2, and the resonance frequency of the vibrating body is fm, 0.73 · fm <fs1 <1.2 · fm, and 0 It is related with the apparatus characterized by satisfy | filling .73 * fm <fs2 <1.2 * fm.
According to another aspect of the present invention, a vibration body including an elastic body, a first electro-mechanical energy conversion element fixed to the elastic body, and a second electro-mechanical energy conversion element, a drive circuit, Have
The drive circuit includes a first inductor and a first capacitor connected in series to the first electro-mechanical energy conversion element, and a second connected in series to the second electro-mechanical energy conversion element. An inductor and a second capacitor,
First vibration mode vibrations and second vibration mode vibrations having different orders are generated in the vibration body by switching over time, or vibrations in the first vibration mode having different orders are generated in the vibration body. And an alternating voltage for generating a vibration in which the vibrations of the second vibration mode are superimposed are applied to the first and second electro-mechanical energy conversion elements, respectively, and the first and second vibrations having different orders from each other. The alternating voltage applied to each of the first electro-mechanical energy conversion element and the second electro-mechanical energy conversion element in the case of generating vibrations with overlapping modes has different phases and the same frequency. The peak frequency of the alternating voltage applied to the first electromechanical energy conversion element and the second electromechanical energy conversion element is fe, and the driving frequency of the vibrator is f. When a, to an apparatus and satisfies the fe <2 · fd.
Furthermore, according to one aspect of the present invention, an alternating voltage is applied to the electro-mechanical energy conversion element fixed to the elastic body, whereby the vibration body constituted by at least the electro-mechanical energy conversion element and the elastic body is applied. A driving circuit for a vibrating body that generates vibration,
A first inductor and a first capacitor connected in series to the first electro-mechanical energy conversion element; a second inductor connected in series to the second electro-mechanical energy conversion element; And a capacitor
First vibration mode vibrations and second vibration mode vibrations having different orders are generated in the vibration body by switching over time, or vibrations in the first vibration mode having different orders are generated in the vibration body. And an alternating voltage for generating a vibration in which the vibrations of the second vibration mode are superimposed are applied to the first and second electro-mechanical energy conversion elements, respectively, and the first and second vibrations having different orders from each other. The alternating voltage applied to each of the first electro-mechanical energy conversion element and the second electro-mechanical energy conversion element in the case of generating vibrations with overlapping modes has different phases and the same frequency. The peak frequency of the alternating voltage applied to the first electromechanical energy conversion element and the second electromechanical energy conversion element is fe, and the driving frequency of the vibrator is f. When a, and satisfies the fe <2 · fd, a driving circuit of the vibrator.

  According to the present invention, even when the resonance frequency of the vibrating body varies in the frequency band to be used or changes during driving, the fluctuation of the alternating voltage applied to the electromechanical energy conversion element is small, and the stable voltage amplitude Can be provided.

It is a figure which shows the drive circuit of the vibrating body in 1st Embodiment. 1 is a perspective view of an imaging apparatus to which the present invention can be applied. It is a perspective view which shows the structure of the imaging part of the camera main body equipped with the dust removal apparatus. It is a block diagram which shows the control apparatus of the dust removal apparatus which can apply this invention. It is a figure which shows the structure of the conventional drive circuit. It is a graph which shows the frequency of the alternating voltage applied to a piezoelectric element, the amplitude of each vibration which arises in a piezoelectric element, and its voltage waveform in 1st Embodiment. It is a figure which shows the displacement of the 10th-order out-of-plane bending vibration which is excited by the vibrating body and deforms out of plane along the longitudinal direction, the displacement of the 11th-order out-of-plane bending vibration, and the arrangement of the piezoelectric elements. The frequency characteristic of the voltage amplitude of the alternating voltage Vo in the case of using the conventional drive circuit is shown. The simulation result which shows the frequency characteristic of an electric current amplitude and the alternating voltage Vo when the series resonant frequency fs by an inductor and a capacitor is made to correspond substantially with the resonant frequency fm of a vibrating body is shown. It is the result of having simulated the mode of change of the alternating voltage Vo by the change of admittance by calculation. It is a simulation result which shows the mode of the fluctuation | variation of the alternating voltage Vo by the dispersion | variation in the intrinsic capacitance of an inductor, a capacitor, and a piezoelectric element. It is the result of having measured the change of the power supply current with respect to drive time. It is a figure which shows the frequency characteristic of the alternating voltage Vo in the case of satisfying fe <2 * fd. It is a simulation result which shows the mode of the fluctuation | variation of the phase and the alternating voltage Vo with respect to the past according to the change of fs / fm. It is a simulation result which shows the ratio of the phase change amount with respect to the past according to the change of fs / fm. It is a figure which shows the relationship between the inductance L of the inductor according to the peak frequency fe, and the electrostatic capacitance C of a capacitor. It is a figure which shows the drive circuit of the dust removal apparatus using a trans | transformer in 2nd Embodiment. It is a graph which shows the frequency of the alternating voltage applied to the piezoelectric element at the time of standing wave drive in 3rd Embodiment, the amplitude of each vibration which arises in a piezoelectric element, and its voltage waveform.

  Embodiments of a driving circuit for a vibrating body to which the present invention can be applied will be described with reference to the drawings. The vibrating body drive device of the present invention can drive an object such as powder by vibrating the vibrating body. In each of the following embodiments, a dust removing device for removing dust that is powder and a drive circuit thereof will be described as an example. However, the present invention is not limited to powder or the like on a vibrating body by vibrating the vibrating body. Any device that drives an object can be used. In the present invention, powder refers to an object in the range of 1 μm to 100 μm.

  As a device on which the vibrator of the present invention and its drive circuit are mounted, optical devices such as a camera (imaging device), a facsimile device, a scanner, a projector, a copying machine, and a printer are conceivable. In the following embodiments, an example of mounting on an imaging device will be described. In the present invention, an image sensor such as a CCD or CMOS sensor used in an image pickup apparatus such as a camera, which is a photoelectric conversion element, a line sensor used in a copier, a facsimile machine or the like is referred to as a light receiving element.

(First embodiment)
In the present embodiment, a mode in which a dust removing device that excites a traveling wave on a vibrating body to move dust that is powder is mounted on a camera will be described.

(Camera body configuration)
FIG. 2A is a front perspective view of the digital single-lens reflex camera, which is an image pickup apparatus, according to the first embodiment when viewed from the subject side, and shows a state in which the photographing lens is removed. FIG. 2B is a rear perspective view of the camera viewed from the photographer side. A mirror box 202 is provided in the camera body 201 to guide a photographing light beam that has passed through a photographing lens (not shown), and a main mirror (quick return mirror) 203 is disposed in the mirror box 202. The image pickup unit including the dust removing device is provided on a photographing optical axis that passes through a photographing lens (not shown). The main mirror 203 is retracted from the photographing light flux so as to be held at an angle of 45 ° with respect to the photographing optical axis so that the photographer can observe the subject image from the viewfinder eyepiece window 204 and to be directed toward the image sensor. A state of being held in position. A cleaning instruction switch 205 for driving a vibrating body that is a dust removing device is provided on the back of the camera. When the photographer presses the cleaning instruction switch 205, the command device 604 (see FIG. 4) is instructed to drive the dust removing device.

(Configuration of dustproof removal device)
FIG. 3 is a perspective view illustrating the structure of the imaging unit of the camera body 201 equipped with the dust removing device that is a vibrating body. The imaging unit of the camera body 201 is provided with an imaging element 503 that is a light receiving element such as a CCD or CMOS sensor that converts a received subject image into an electrical signal. In addition, the vibrating body 501 is attached so that the space on the front surface of the image sensor 503 is sealed. The vibrating body 501 includes an optical member 502 having a rectangular plate shape that is an elastic body, and a pair of piezoelectric elements 101a (first electric-electrical elements) that are electro-mechanical energy conversion elements fixed to both ends thereof by adhesion. Mechanical energy conversion element) and piezoelectric element 101b (second electro-mechanical energy conversion element). The optical member 502 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 that has passed through the optical member 502 is incident on the image sensor 503.

  Here, the dimensions of the piezoelectric elements 101a and 101b arranged at both ends of the optical member 502 in the thickness direction (vertical direction in the drawing) are such that the thickness of the optical member 502 is increased so that the bending deformation with respect to vibration is increased. It is the same value as the dimension in the direction (vertical direction in the figure). Note that the piezoelectric elements 101a and 101b are simply referred to as the piezoelectric element 101 when it is not necessary to distinguish between them.

(Configuration of control device)
FIG. 4 shows a control device of the dust removing device. The control device includes a command unit 604, pulse generation circuits 603a and 603b, switching circuits 602a and 602b, a power supply circuit 605, and drive circuits 601a and 601b. The command unit 604 sends frequency information, phase information, and pulse width information as parameters of the alternating voltage signal to the pulse generation circuits 603a and 603b. As the pulse generation circuit, for example, a general digital oscillator or the like is used. The frequency is set in the vicinity of the intermediate value of the resonance frequency of the vibrations in two vibration modes (out-of-plane bending vibration) generated in the vibrating body 501, and the same frequency is set in each of the pulse generation circuits 603 a and 603 b. The vibration mode will be described later with reference to FIG. The phase is set so that different values are input to the pulse generation circuits 603a and 603b and the phase difference of the output alternating voltage signals is different (for example, the phase difference is 90 °). The pulse width (pulse duty) is appropriately adjusted so as to obtain a desired voltage amplitude, and is individually set in the pulse generation circuits 603a and 603b.

  The digital alternating voltage signal output from the pulse generation circuit 603 is input to the switching circuits 602a and 602b, and is output as an analog alternating voltage Vi based on the voltage supplied from the power supply circuit 605. As the power supply circuit, a general DC power supply circuit, a DC-DC converter circuit, or the like is used. A general H bridge circuit is used for the switching circuit.

  The alternating voltage Vi is input to the drive circuits 601a and 601b, respectively, and the voltage amplitude is boosted and converted into a SIN waveform, and then output as the alternating voltage Vo. The output alternating voltage Vo is applied to each of the piezoelectric elements 101a and 101b, and two out-of-plane bending vibrations are generated in the vibrating body 501 simultaneously. This synthetic vibration becomes a traveling wave, and dust on the surface of the optical member 502 can be moved in a desired direction. The configuration of the drive circuits 601a and 601b, which is a feature of the present invention, will be described later with reference to FIG.

  The digital alternating voltage signal output from the pulse generation circuit 603 is input to the switching circuits 602a and 602b, and is output as an analog alternating voltage Vi based on the voltage supplied from the power supply circuit 605. As the power supply circuit, a general DC power supply circuit, a DC-DC converter circuit, or the like is used. A general H bridge circuit is used for the switching circuit.

  The alternating voltage Vi is input to the drive circuits 601a and 601b, respectively, and the voltage amplitude is boosted and converted into a SIN waveform, and then output as the alternating voltage Vo. The alternating voltage Vo is applied to each of the piezoelectric elements 101a and 101b, and two out-of-plane bending vibrations are generated in the vibrating body 501 simultaneously. This synthetic vibration becomes a traveling wave, and dust on the surface of the optical member 502 can be moved in a desired direction.

(Drive frequency setting)
Next, setting of the driving frequency will be described. FIG. 6A is a graph showing the frequency of the alternating voltage applied to the piezoelectric element 101 and the amplitude of each vibration generated in the piezoelectric element 101. In FIG. 6, f (m) is the resonance frequency of the m-th order out-of-plane bending vibration, and f (m + 1) is the resonance frequency of the (m + 1) -order out-of-plane bending vibration. When the frequency fd of the alternating voltage applied to the piezoelectric element 101 is set to f (m) <fd <f (m + 1), resonance phenomena of the m-th order out-of-plane bending vibration and the (m + 1) -th order out-of-plane bending vibration, respectively. The vibration of the frequency fd whose amplitude was expanded by is obtained. The time period of each vibration is the same. On the other hand, as the frequency fd of the alternating voltage applied to the piezoelectric element 101 is made lower than f (m), the amplitude of the (m + 1) -order out-of-plane bending vibration becomes smaller, and the frequency fd becomes higher than f (m + 1). The amplitude of the m-th order out-of-plane bending vibration is reduced.

(Description of vibration mode)
FIG. 7 shows the displacement of the tenth-order out-of-plane bending vibration, the displacement of the eleventh-order out-of-plane bending vibration, and the arrangement of the piezoelectric elements 101a and 101b that are excited by the vibrating body 501 and deformed out of plane along the longitudinal direction. It is a schematic diagram shown. The horizontal axis is the position of the vibrating body 501 in the longitudinal direction. The vertical axis represents out-of-plane vibration displacement. In FIG. 7, the 10th-order out-of-plane bending vibration is shown as a first vibration mode by a waveform A (solid line), and the 11th-order out-of-plane bending vibration is shown as a second vibration mode by a waveform B (broken line). The first vibration mode A and the second vibration mode B are out-of-plane bending vibration modes in which the vibrating body 501 is bent and deformed in the thickness direction of the optical member 502.

  When the drive circuits 601a and 601b apply the alternating voltage Vo described above to the piezoelectric elements 101a and 101b, vibrations in the first vibration mode A and the second vibration mode B are simultaneously generated in the vibration body 501. Superimposed. In the present embodiment, as the minimum necessary vibration mode for removing dust, the 10th-order bending vibration mode is used as the first vibration mode, and the 11th-order bending vibration mode is used as the second vibration mode. However, it is not limited to this. Here, the optically effective portion corresponding to the image sensor 503 has a range shown in FIG. The deformed shape of the first vibration mode A is in reverse phase (phase difference 180 °) at the left end and the right end. On the other hand, the deformed shape of the second vibration mode B is in phase (phase difference 0 °) at the left end and the right end. That is, if the phase difference between the alternating voltages applied to the piezoelectric elements 101a and 101b is 180 °, only the first vibration mode A is generated, and conversely, if the phase difference is 0 °, the second vibration mode B is generated. Only occurs. Therefore, if the phase difference is 90 °, the first vibration mode A and the second vibration mode B can be generated simultaneously, and a traveling wave due to the combined vibration is generated in the right direction in the figure.

  FIG. 6B is a diagram illustrating an example of an alternating voltage applied to each piezoelectric element when simultaneously exciting vibration modes having different orders. The alternating voltage Vo1 is a voltage waveform applied to the piezoelectric element 101a, and the alternating voltage Vo2 is a voltage waveform applied to the piezoelectric element 101b. The vertical axis represents voltage amplitude, and the horizontal axis represents time. The frequencies of the alternating voltages Vo1 and Vo2 are constant at the aforementioned fd, and the phase difference between the alternating voltages is 90 °. However, the alternating voltages Vo1 and Vo2 only need to have different phases, and the phase difference is not limited to 90 °.

  In the dust removing device, the dust adhering to the surface of the optical member 502 moves so as to be repelled by receiving a normal force on the surface of the optical member 502 when the optical member 502 pushes the dust out of the plane. . That is, at each phase of the driving frequency cycle, when the speed of the combined vibration displacement of the vibrating body 501 is positive, the dust is pushed out of the plane, and the dust moves by receiving a force in the normal direction of the combined vibration displacement in this phase. I will do it. In FIG. 7, it is possible to move and remove the dust in the right direction of FIG. 7 by repeatedly applying vibration to the dust adhering to the surface of the effective portion of the optical member 502.

(Description of drive circuit: LC boost)
The drive circuit according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1A is a diagram illustrating a drive circuit of the dust removing device according to the first embodiment. As a configuration of the drive circuit, an inductor 102 and a capacitor 103 are connected to the piezoelectric element 101 in series. The capacitor 103 is connected to the lower side of the piezoelectric element 101 in FIG. 1, but may be connected to the upper side (between the inductor 102 and the piezoelectric element 101). Further, as shown in FIG. 1C, a resistor 104 may be connected in parallel to the piezoelectric element 101. The resistor 104 is set to about 1 MΩ where almost no current flows, so that power consumption does not occur in the resistor portion. By providing the resistor 104, the potential at the connection point between the capacitor 103 and the piezoelectric element 101 is determined, and a stable alternating voltage can be applied to both ends of the piezoelectric element.

  Here, as the inductor 102, an inductance element such as a coil can be used. As the capacitor 103, a capacitive element such as a film capacitor can be used. A feature of the present invention is that the series resonance frequency of the inductor 102 and the capacitor 103 is substantially matched with the resonance frequency of the vibrating body 501 (set within an allowable range described later).

  Here, an equivalent circuit of the piezoelectric element 101 will be described with reference to FIG. FIG. 1B shows the piezoelectric element 101 in an equivalent circuit. The equivalent circuit of the piezoelectric element 101 is an RLC series circuit (an equivalent coil 301b having a self-inductance Lm, an equivalent capacitor 301c having a capacitance Cm, and an equivalent resistor 301d having a resistance value Rm) in the mechanical vibration portion of the vibrating body 501, and an RLC series. And a capacitor 301a as the intrinsic capacitance Cd of the piezoelectric element 101 connected in parallel to the circuit.

  In the present invention, the series resonance frequency of the inductor 102 and the capacitor 103 is defined as fs, and the resonance frequency of the vibrating body 501 is defined as fm. When the self-inductance of the inductor 102 is L and the capacitance of the capacitor 103 is C,

It becomes. By making fs and fm substantially coincide with each other, the frequency characteristic of the alternating voltage Vo in the vicinity of fm can be made smooth.

  Here, the configuration of a conventional drive circuit in which only the inductor 102 is connected in series to the piezoelectric element 101 will be described with reference to FIG. As shown in FIG. 5, by connecting an inductor 102 in series with the piezoelectric element 101, an LC series resonance circuit including the intrinsic capacitance of the piezoelectric element 101 and the inductor 102 is formed. The voltage amplitude of the alternating voltage Vi is boosted to a desired voltage by the LC series resonance circuit, and the alternating voltage Vo is output.

  FIG. 8 shows the frequency characteristics of the voltage amplitude of the alternating voltage Vo when a conventional drive circuit is used. The horizontal axis represents frequency and the vertical axis represents voltage amplitude. Each plot shows characteristics when the value of the inductor 102 is changed from 40 μH to 90 μH. In FIG. 8, f (m) is a resonance frequency of m-th order out-of-plane bending vibration, and f (m + 1) is a resonance frequency of (m + 1) -order out-of-plane bending vibration. The frequency fd of the alternating voltage Vo applied to the piezoelectric element 101 is set to f (m) <fd <f (m + 1). FIG. 8 shows that the amplitude change of the alternating voltage Vo occurs near fm and f (m + 1). Further, it can be seen that as the value of the inductor 102 is increased, fluctuations in voltage amplitude in the vicinity of fm and f (m + 1) and fd are increased. If the value of the inductor 102 is reduced, the fluctuation of the voltage amplitude is reduced, but a desired voltage amplitude cannot be produced because the step-up rate is reduced. Further, when the value of the inductor 102 is reduced, the electric resonance frequency fe of the LC series resonance is shifted to a high frequency, so that the harmonic component of the drive frequency fd is superimposed on the fundamental wave and the waveform is distorted. When the waveform distortion is large, unnecessary vibration is excited in the vibrating body 501.

  As in the conventional example, the change in the amplitude of the alternating voltage Vo near fm and f (m + 1) is caused by the change in impedance due to the self-inductance Lm and the capacitance Cm of the mechanical vibration portion of the vibrating body 501. Because. On the other hand, in the present invention, matching (matching) can be achieved with respect to the impedance of the mechanical vibration portion of the vibrating body 501 by substantially matching fs and fm. Therefore, as a result, it is considered that the change in the amplitude of the alternating voltage Vo can be reduced. Furthermore, by smoothing the frequency characteristics of the alternating voltage Vo near fm, changes in the alternating voltage Vo due to changes in admittance (equivalent resistance 301d) and variations in the inductor 102 and capacitor 103 can be reduced. This is considered to be because the frequency characteristics are less affected by variations in the elements in the vicinity of fm because matching is performed with respect to the impedance of the mechanical vibration portion of the vibrating body 501.

(Simulation result: comparison of voltage amplitude and current between the example of the present invention and the conventional example)
FIG. 9 shows a simulation result showing the frequency characteristics of the alternating voltage Vo when the series resonance frequency fs of the inductor 102 and the capacitor 103 is substantially matched with the resonance frequency fm of the vibrating body 501. In this embodiment, the drive circuit has the configuration shown in FIG. The vibrating body 501 of this embodiment uses two out-of-plane bending vibrations, and the resonance frequencies fm are two, f (m) and f (m + 1). In this embodiment, the series resonance frequency fs is set as fs = 0.83 · f (m) according to the resonance frequency f (m). Ideally, it is desirable to completely match fs and fm. However, since it is difficult to increase the voltage amplitude step-up rate, it is set to a value smaller than fm. According to the calculation, when fs is smaller than fm, the boosting rate increases, and when fs is larger than fm, the boosting rate tends to decrease. Although the series resonance frequency fs is adjusted to f (m), a desired effect can be obtained even at a frequency in the vicinity of f (m + 1).

  In this simulation, the self-inductance Lm of the equivalent coil 301b is 0.04H, and the capacitance Cm of the equivalent capacitor 301c is 44 pF. Further, f (m) was 120 kHz, f (m + 1) was 128 kHz, and drive frequency fd = 123 kHz. The self-inductance L of the inductor 102 was set to 82 μH, and the capacitance C of the capacitor 103 was set to 31 nF (fs = 0.83 · fm). In addition, although the plots are overlapped, the inductor 102 is set to 68 μH and the capacitor 103 is set to 42 nF (fs = 0.79 · fm). Further, as a conventional example, a comparative example in which the inductor 102 in the case of using the configuration of the drive circuit of FIG. 5 is set to 68 μH is shown.

(Voltage stabilization)
FIG. 9A shows the frequency characteristics of the amplitude of the current flowing in the drive circuit. FIG. 9B is a diagram illustrating frequency characteristics of the voltage amplitude of the alternating voltage Vo. As shown in FIGS. 9A and 9B, the frequency characteristics of the alternating voltage Vo in the vicinity of f (m) and f (m + 1) can be made smooth by substantially matching fs and fm. Become. That is, a stable voltage is applied with respect to the change in the resonance frequency of the vibrating body 501, and the change in the drive current can be reduced. For example, when the resonance frequency f (m + 1) decreases with time during driving, the amplitude of the alternating voltage increases and the driving current increases in the conventional example, but the change is reduced in the present invention. It becomes possible to do.

  The amplitude of the alternating voltage Vo is set to have a peak at a certain frequency by using electrical resonance between the inductor 102 and the capacitor 301a that is the specific capacitance of the capacitor 103 and the piezoelectric element 101. When the peak frequency of the alternating voltage Vo is defined as fe, the voltage fluctuation is small even if the drive frequency fd of the vibrating body 501 is changed in the frequency band between fm and fe by setting fe to a frequency higher than fm. Frequency characteristics can be obtained. In this example, the peak frequency fe was set to 180 to 200 kHz.

(Reduction of the impact of admittance changes)
FIG. 10 shows the effect of reducing the fluctuation of the alternating voltage Vo. FIG. 10 shows the result of simulation by calculation of the change in the alternating voltage Vo due to the change in admittance. The change in admittance was calculated by changing the value of the equivalent resistance 301d from 10% to 100% with respect to the reference value. The smaller the equivalent resistance, the greater the admittance. FIG. 10A shows a conventional example, and FIG. 10B shows this example. This example shows that the influence of the change in admittance is reduced to about 20% of the conventional example.

(Reduction of the effect of variation due to L, C, and Cd)
FIG. 11 is a simulation result showing how the alternating voltage Vo varies due to variations in the intrinsic capacitance of the inductor 102, capacitor 103, and piezoelectric element 101. The Monte Carlo method assumes that the variation of the self-inductance L of the inductor 102 is ± 20%, the variation of the capacitance C of the capacitor 103 is ± 10%, and the variation of the capacitor 301a, which is the intrinsic capacitance Cd of the piezoelectric element 101, is ± 10%. The random distribution with uniform distribution was calculated. FIG. 11A shows a conventional example, and FIG. 11B shows this example. In this example, it can be seen that the influence of the element variation of the entire drive circuit including the piezoelectric element 101 is reduced to about 70% of the conventional example.

(Reduction of current rise)
Actually, the vibrator 501 was driven by the drive circuit of this example, and the power supply current was compared. FIG. 12 shows the result of measuring the change in the power supply current with respect to the driving time. The power source used was a 12V DC power source. In the driving circuit of the conventional example, the power supply current increased about twice as much as the initial value after 20 seconds, but in the driving circuit of the present example, it increased by about 40%. Therefore, power consumption can be reduced.

(Acceptable range of relationship between fs and fm)
Next, a permissible range of the relationship between the series resonance frequency fs of the inductor 102 and the capacitor 103 connected in series to the piezoelectric element 101 and the resonance frequency fm of the vibrating body 501 (a range in which fs and fm substantially coincide). Will be described. In the above embodiment, fm and fs are completely matched, but the present invention is not limited to the case where fs and fm are completely matched. That is, by setting fs and fm to close values within a certain range, the frequency characteristics of the alternating voltage Vo in the vicinity of fm can be made smooth. However, the effect is greater as fs is closer to fm.

  In the present invention, attention is paid to the phase change of the alternating voltage Vo in the vicinity of the resonance frequency fm of the piezoelectric element 101 in order to obtain the effective fs range. FIG. 14A is a simulation result showing the phase of the alternating voltage Vo. The horizontal axis represents the frequency, and shows the change in the phase of Vo from 40 kHz to 48 kHz with the resonance frequency fm being 44.142 kHz. In this simulation, using the drive circuit of FIG. 1A, the ratio of the series resonance frequency fs by the inductor 102 and the capacitor 103 to fm (referred to as fs / fm) is changed in the range of 0.73 to 1.2. This was plotted.

  Here, fs / fm was changed by adjusting the values of L and C so that the peak frequency fe was always 61.798 kHz (= 1.4 · fm). The reason for making the peak frequency fe constant is that the amplitude of Vo in the vicinity of the resonance frequency fm of the vibrating body 501 greatly varies depending on the value of fe. In addition, as a conventional configuration serving as a reference for comparison, calculation was performed using the circuit of FIG. 5, and the result was plotted. In this case, the self-inductance L of the inductor 102 was set to 1.97 mH, and the peak frequency fe of the alternating voltage Vo was set to 61.798 kHz (= 1.4 · fm).

  From FIG. 14A, it can be seen that the Vo of the configuration of the conventional example is delayed in phase by about 60 ° at the maximum. On the other hand, when fs / fm = 1, the phase change of Vo hardly occurs. When fs / fm = 1, the self-inductance L of the inductor 102 is 4.17 mH, and the capacitance C of the capacitor 103 is 3.12 nF. As a tendency, the fs / fm <1 increases the phase change to the negative side, and the fs / fm> 1 increases the phase change to the positive side.

  FIG. 14B shows the result of a simulation showing the change of the alternating voltage Vo according to the frequency in order to investigate the relationship between the phase change of the alternating voltage Vo and the amplitude fluctuation of the alternating voltage Vo in FIG. is there. The simulation conditions are the same as those in FIG. 14A. The fs / fm changed in the range of 0.73 to 1.2 and the configuration of the conventional example were compared and plotted. It can be seen that the phase change amount shown in FIG. 14B corresponds to the tendency of the voltage fluctuation amount shown in FIG. That is, the greater the change in the phase of Vo, the greater the amplitude fluctuation of Vo.

FIG. 15 is a simulation result showing the ratio of the phase change amount with respect to the configuration of the conventional example according to the change in fs / fm. The horizontal axis is fs / fm, which is the ratio of fs to the resonance frequency fm of the vibrating body 501. The vertical axis represents the ratio of the phase change amount with respect to the configuration of the conventional example, and was calculated as follows. First, the absolute value of the phase change amount of Vo in the case of using the configuration of the conventional example was calculated in the range of 40 kHz to 48 kHz, and the maximum value was detected. This is referred to as “the maximum phase change amount of the conventional configuration”. Subsequently, in the configuration of FIG. 1A, the absolute value of the phase change amount of Vo was calculated in the range of 40 kHz to 48 kHz using fs / fm as a parameter, and the maximum value was detected. This is defined as “the maximum phase change amount according to fs / fm”. The ratio of the amount of phase change to the configuration of the conventional example is calculated by calculating the ratio between the two
“Maximum amount of phase change according to fs / fm” / “Maximum amount of phase change of conventional configuration”
This is taken as the vertical axis.

In the present invention, as shown in FIG. 15, the condition that the ratio of the phase change amount to the conventional configuration is halved is defined as a threshold value, and the range in which the frequency characteristic of the alternating voltage Vo near fm can be made smooth is defined. Asked. As a result, the range where the effect of fs / fm can be obtained is
0.73 · fm <fs <1.2 · fm
It became. In the above range, the peak frequency fe was calculated as 61.798 kHz (= 1.4 · fm), and the specific capacitance Cd of the capacitor 301a of the piezoelectric element 101 was calculated as 3.5 nF, but the peak frequency fe and the specific capacitance Cd were calculated. Even if the value of is changed, almost the same calculation result is obtained. Note that the self-inductance Lm of the equivalent coil 301b in the piezoelectric element 101 is 0.1H, the capacitance Cm of the equivalent capacitor 301c is 130 pF, and the resistance value Rm of the equivalent resistor 301d is 1 kΩ.

  Therefore, by suppressing the amount of change in the phase difference of the alternating voltage Vo to half or less according to the above range, the amount of change in Vo can be suppressed to approximately half or less compared to the conventional case. That is, even if fs and fm are not completely matched, the frequency characteristic of the alternating voltage Vo in the vicinity of fm can be made smoother than before by satisfying the relationship between fs and fm.

(How to determine the values of inductor 102 and capacitor 103)
Next, how to determine the values of the inductor 102 and the capacitor 103 will be described. Since the series resonance frequency fs is determined by the product of the inductance L of the inductor 102 and the capacitance C of the capacitor 103, there are many combinations even with the same fs. In contrast, one combination can be obtained by first determining the peak frequency fe of the alternating voltage Vo.

  The peak frequency fe of Vo can be calculated from the inductance L of the inductor 102, the capacitance C of the capacitor 103, and the intrinsic capacitance Cd of the piezoelectric element 101. The expression for the peak frequency fe is

It becomes. Here, in order to calculate the actual peak frequency fe, it is necessary to regard the piezoelectric element 101 equivalently as a capacitor and calculate it using Cd ′ considering the influence of the RLC series circuit of the mechanical vibration portion. For example, when the influence of the RLC series circuit of the mechanical vibration part corresponds to a capacitance change of 44 pF,
Cd ′ = Cd−44 pF
Can be calculated as

  By determining the value of fe from the expression of the peak frequency fe, the functions of L and C can be obtained. FIG. 16 is a diagram illustrating the relationship between the inductance L of the inductor 102 and the capacitance C of the capacitor 103 according to the peak frequency fe. The horizontal axis is the value of C, and the vertical axis is the value of L. When fe is 1.4 · fm, 1.5 · fm, and 2 · fm, the values of L and C obtained from (Equation 1-3) are plotted. Further, a plot is also shown when the product LC of L and C is LmCm, that is, when the series resonance frequency fs matches fm. As described above, Lm represents the self-inductance of the equivalent coil 301b, and Cm represents the capacitance of the equivalent capacitor 301c.

  From FIG. 16, the function of the inductor and the capacitor when fe is fixed intersects with the function of LC = LmCm at one point. This is the optimum value of inductance L and capacitance C at which fs matches fm. For example, when fe is 1.4 · fm, L is 4.17 mH and C is 3.12 nF.

Next, the value of fe will be described. In the present invention, the condition of the peak frequency fe is that the drive frequency of the vibrating body 501 is fd.
fe <2 · fd
It is preferable to set so as to satisfy the relationship. The reason for this will be described next.

  FIG. 13 is a diagram illustrating frequency characteristics of the alternating voltage Vo when fe <2 · fd is satisfied. 2 · fd is the second harmonic frequency of the drive frequency fd. As the waveform of the alternating voltage Vo, a SIN waveform having as few secondary harmonic components and tertiary harmonic components as possible is required. Since the drive waveform of the alternating voltage Vo in the actual machine is adjusted to have a pulse duty of 10% to 50%, it is particularly necessary to reduce the third harmonic component. Therefore, by setting the peak frequency fe to a value lower than 2 · fd, the amplitude of the alternating voltage Vo at the frequency 2 · fd of the third harmonic component can be made smaller than the drive frequency fd. For example, when the drive frequency fd is 46 kHz, 2 · fd is 92 kHz. In this case, if the inductance L of the inductor 102 is set to 4 mH and the capacitance C of the capacitor 103 is set to 3.25 nF, the peak frequency fe is 61.3 kHz, and the above condition can be satisfied.

(Second Embodiment)
Next, a second embodiment will be described. This embodiment differs from the first embodiment in that the voltage is boosted using a transformer. Note that the configuration of the dust removing device, which is a vibrating body, and the vibration mode are the same as those in the first embodiment, and only the drive circuit will be described below.

(Description of drive circuit: transformer booster)
FIG. 17A is a diagram showing a drive circuit of the dust removing device in the second embodiment of the present invention. The configuration of the drive circuit is such that the secondary coil 401 b of the transformer 401 is connected in parallel to the piezoelectric element 101. A capacitor 103 is connected in series to the transformer primary coil 401a. Here, a capacitive element such as a film capacitor can be used for the capacitor 103. Further, by weakening the coupling of the transformer 401, the leakage inductance of the transformer primary coil 401a and the leakage inductance of the transformer secondary coil 401b can be used as inductors.

This leakage inductance is equivalently shown as inductors 102a (leakage inductance of transformer primary coil 401a) and 102b (leakage inductance of transformer secondary coil 401b) in FIG. These two leakage inductances and the capacitor 103 form a series resonance. The capacitor 103 is connected to the lower side of the transformer primary coil 401a in FIG. 17A, but may be connected to the upper side (between the inductor 102a and the transformer primary coil 401a). Here, the series resonance frequency of the primary side leakage inductance 102a, the secondary side leakage inductance 102b, and the capacitor 103 is defined as fs, and the resonance frequency of the vibrating body 501 is defined as fm. The leakage inductance 102a of the transformer primary coil 401a _{L 1,} the turns ratio for the primary coil 401a of the leakage inductance 102b of the transformer secondary coil 401b _L 2, the secondary coil 401b N, a capacitor 103 C Then,

It becomes. As described above, Lm and Cm are equivalent circuit constants of mechanical vibration of the piezoelectric element 101, Lm is the self-inductance of the equivalent coil 301b, and Cm is the capacitance of the equivalent capacitor 301c.

As in the first embodiment, the series resonance frequency fs is set to a value close to fm in the following range without being completely matched with the resonance frequency fm of the vibrating body 501, so that the alternating voltage near fm is set. The frequency characteristic of Vo can be made smooth.
0.73 · fm <fs <1.2 · fm

Here, in the case of a configuration using a transformer, the coefficient relating to LC in the calculation formula of fs differs depending on whether the inductor 102 and the capacitor 103 are connected to the primary side or the secondary side of the transformer. The configuration is roughly divided into the following four.
(1) A configuration in which an LC is connected to the primary side of the transformer.
(2) A configuration in which an LC is connected to the secondary side of the transformer.
(3) A configuration in which L is connected to the primary side of the transformer and C is connected to the secondary side of the transformer.
(4) A configuration in which C is connected to the primary side of the transformer and L is connected to the secondary side of the transformer.

For the above (1) and (2), the coefficient relating to LC is 1. On the other hand, (3) is N ² · LC. This is because L on the primary side corresponds to the square of the winding ratio N of the transformer when converted to the secondary side. Further, (4) is (1 / N ² ) · LC. This is because the primary side C, when converted to the secondary side, corresponds to 1 / square of the winding ratio N of the transformer.

  The method for determining the values of the inductor 102 and the capacitor 103 is the same as in the first embodiment. That is, one combination can be obtained by first determining the peak frequency fe of the alternating voltage Vo.

Further, the peak frequency fe is the same as in the first embodiment when the drive frequency of the vibrating body 501 is fd.
fe <2 · fd
Set to satisfy the relationship.

(Modification 1 of 2nd Embodiment)
FIG. 17B is a diagram illustrating a first modification of the drive circuit of the dust removing device according to the second embodiment. The configuration of the drive circuit is such that the secondary coil 401b of the transformer 401 is connected in parallel to the piezoelectric element 101, and the inductor 102 and the capacitor 103 are connected in series to the transformer primary coil 401a. The inductor 102 and the capacitor 103 may have a configuration other than that shown in FIG. 17B as long as the inductor 102 and the capacitor 103 are connected in series to the transformer primary coil 401a. By connecting the inductor 102 to the primary side of the transformer 401, an element having an inductance value smaller than 1 / N ² can be used as compared with the case where it is connected to the secondary side. Here, N is a winding ratio. Further, the capacitor 103 can be connected to the primary side of the transformer 401 so that an element having a withstand voltage of 1 / N can be used as compared with the case of connecting to the secondary side.

  When the inductor 102 is L and the capacitor 103 is C, the series resonance frequency fs is the same as in (Equation 1-1),

It becomes. This may be substantially matched with the resonance frequency fm of the vibrating body 501.

(Modification 2 of the second embodiment)
FIG.17 (c) is a figure which shows the modification 2 of the drive circuit of the dust removal apparatus in the 2nd Embodiment of this invention. The drive circuit is configured such that the secondary coil 401b of the transformer 401 is connected in parallel to the piezoelectric element 101, the capacitor 103 is connected in series to the transformer primary coil 401a, and the inductor 102 is connected in series to the transformer secondary coil 401b. Is connected. By connecting the inductor 102 to the secondary side of the transformer 401, an element having a current allowable value as small as 1 / N can be used as compared with the case where it is connected to the primary side. Here, N is a winding ratio. When the inductance of the inductor 102 is L and the capacitance of the capacitor 103 is C, the series resonance frequency fs is

It becomes. This may be substantially matched with the resonance frequency fm of the vibrating body 501.

(Modification 3 of the second embodiment)
FIG. 17D is a diagram showing a third modification of the drive circuit of the dust removing device according to the second embodiment of the present invention. The drive circuit is configured such that the secondary coil 401b of the transformer 401 is connected in parallel to the piezoelectric element 101, the inductor 102 is connected in series to the transformer primary coil 401a, and the capacitor 103 is connected in series to the transformer secondary coil 401b. Is connected. By connecting the inductor 102 to the primary side of the transformer 401, an element having an inductance as small as 1 / N ² can be used as compared with the case where it is connected to the secondary side. Further, by connecting the capacitor 103 to the secondary side of the transformer 401, an element having a smaller capacitance of 1 / N ² than that in the case of connecting to the primary side can be used. In this case, fs is the series resonance frequency.

It becomes. This may be substantially matched with the resonance frequency fm of the vibrating body 501.

(Modification 4 of the second embodiment)
FIG. 17E is a diagram showing a fourth modification of the drive circuit of the dust removing device in the second embodiment of the present invention. The configuration of the drive circuit is such that the secondary coil 401b of the transformer 401 is connected in parallel to the piezoelectric element 101, and the inductor 102 and the capacitor 103 are connected in series to the transformer secondary coil 401b. By connecting the inductor 102 to the secondary side of the transformer 401, an element having a current allowable value as small as 1 / N can be used as compared with the case where it is connected to the primary side. Further, by connecting the capacitor 103 to the secondary side of the transformer 401, an element having a smaller capacitance of 1 / N ² than that in the case of connecting to the primary side can be used. In this case, fs is the series resonance frequency.

It becomes. This may be matched with the resonance frequency fm of the piezoelectric element 101.

(Third embodiment)
Next, a third embodiment will be described. This embodiment is different from the first embodiment in that two vibration modes are alternately excited in the vibrating body 501. The configurations of the vibrating body 501 and the drive circuit are the same as those of the first and second embodiments, and the setting of the frequency information and phase information of the command unit in the control device is different from that of the first and second embodiments. The excited vibration becomes standing wave vibration.

(Standing wave vibration and driving method)
FIG. 18A is a graph showing the frequency of the alternating voltage applied to the piezoelectric element and the amplitude of each vibration generated in the piezoelectric element. Here, f (m) is the resonance frequency of the m-th order out-of-plane bending vibration, and f (m + 1) is the resonance frequency of the (m + 1) -order out-of-plane bending vibration. In FIG. 18, f (m) is a 10th-order out-of-plane bending vibration mode (first vibration mode) excited by reverse-phase driving, and f (m + 1) is an 11th-order out-of-plane bending vibration excited by in-phase driving. Mode (second vibration mode). In the present embodiment, the standing waves of the two vibration modes are alternately excited to remove dust attached to the surface of the optical member that is an elastic body.

  Although the first embodiment has been described with reference to FIG. 7, the tenth-order out-of-plane bending vibration is set to the first vibration mode (waveform A (solid line)) in the present embodiment, and the eleventh-order out-of-plane Let bending vibration be the second vibration mode (waveform B (broken line)). The first vibration mode A and the second vibration mode B are out-of-plane bending vibration modes in which the vibrating body 501 is bent and deformed in the thickness direction of the optical member 502. The deformed shape of the first vibration mode A is in reverse phase (phase difference 180 °) at the left end and the right end. On the other hand, the deformed shape of the second vibration mode B is in phase (phase difference 0 °) at the left end and the right end. That is, if the phase difference between the alternating voltages applied to the piezoelectric element 101a and the piezoelectric element 101b is 180 °, only the first vibration mode A is excited in the resonance state, and conversely, if the phase difference is 0 °, the second vibration mode A is excited. Vibration mode B is excited.

  FIG. 18B is a diagram illustrating an example of an alternating voltage applied to each piezoelectric element when two standing wave oscillations having different orders are alternately excited. The control device described in FIG. 4 is used. The alternating voltage Vo1 indicates a voltage waveform applied to the piezoelectric element 101a, and the alternating voltage Vo2 indicates a voltage waveform applied to the piezoelectric element 101b. The vertical axis represents voltage amplitude, and the horizontal axis represents time.

  In order to alternately generate the vibrations of the two vibration modes, first, an alternating voltage having a frequency near the natural frequency of the tenth bending vibration mode of the vibrating body 501 and a phase difference of 180 ° is applied to the piezoelectric element 101a. , 101b (reverse phase driving). By applying such an alternating voltage, a tenth-order bending vibration mode is excited in the vibrating body 501. After exciting the tenth-order bending vibration mode for a predetermined time, next, an alternating voltage having a frequency near the natural frequency of the eleventh-order vibration mode of the vibrating body 501 and a phase difference of 0 ° is applied to the piezoelectric element. Applied to 101a and 101b (in-phase drive). By applying such an alternating voltage, the eleventh-order bending vibration mode is excited in the vibrating body 501.

  When the first vibration mode is excited, even if the phase difference between the alternating voltages slightly deviates from 180 ° within the error range due to the element variation of the drive circuit, the vibration body 501 is generated. When the vibration in the first vibration mode is dominant as the vibration, the phase difference is assumed to be 180 °. Similarly, when the second vibration mode is excited, even if the phase difference of each alternating voltage is slightly deviated from 0 ° within the error range due to the element variation of the drive circuit, the vibration body 501 When the vibration in the second vibration mode is dominant as the generated vibration, the phase difference is assumed to be 0 °.

  By repeating the above driving (reverse phase driving and in-phase driving), vibrations in the 10th and 11th out-of-plane bending vibration modes are alternately excited. As shown in FIG. 18B, the alternating voltages Vo1 and Vo2 at the time of driving may be gradually swept from the high frequency side to the low frequency side in the vicinity of each natural frequency. By setting the frequency of the alternating voltage in the vicinity of the natural frequency of the vibrating body 501, a large amplitude can be obtained even with a small applied voltage, and efficiency can be improved.

  As described above, by causing the vibration body 501 to vibrate in the first vibration mode, the vibration member 501 has a function of separating dust attached to the optical member 502 at the antinode position of vibration in the first vibration mode. Specifically, when an acceleration equal to or greater than the adhesion force of the dust attached to the optical member 502 is applied to the dust by the vibration in the first vibration mode, the dust is separated from the optical member 502. Further, by causing the vibration body 501 to vibrate in the second vibration mode, the vibration member 501 has a function of separating dust attached to the optical member 502 in the vicinity of the vibration node in the first vibration mode. The reason why the standing waves having different orders are excited is that the positions of the nodes of the two standing waves are shifted to prevent the optical member 502 from having a portion where no amplitude is generated.

  In addition, you may excite the standing wave of one out-of-plane bending vibration in the vibration body 501 of a dust removal apparatus by applying the said alternating voltage only to one of piezoelectric element 101a, 101b. Further, when the vibrations of vibration modes of different orders are generated by switching in time as in the present embodiment, the number of piezoelectric elements provided in the elastic body is not limited to the two cases as described above, and only one may be used. In this case, there is no phase difference setting, and driving is performed by simply sweeping the frequency of the alternating voltage applied to the piezoelectric element.

101 Piezoelectric element 102 Inductor L
102a Leakage inductance of transformer primary coil 102b Leakage inductance of transformer secondary coil 103 Capacitor C
201 Camera body 301a Specific capacitance Cd of vibrating body
301b Equivalent circuit constant Lm of mechanical vibration
301c Equivalent circuit constant Cm of mechanical vibration
301d Equivalent circuit constant Rm of mechanical vibration
401 Transformer 401a Transformer primary coil 401b Transformer secondary coil 501 Vibrating body 502 Optical member 503 Imaging element 601 Drive circuit 602 Switching circuit 603 Pulse generation circuit 604 Command unit 605 Power supply circuit

Claims (12)

A vibrating body comprising: an elastic body; a first electro-mechanical energy conversion element fixed to the elastic body; and a second electro-mechanical energy conversion element;
A drive circuit;
Have
The drive circuit is
A first inductor and a first capacitor connected in series to the first electro-mechanical energy conversion element;
A second inductor and a second capacitor connected in series to the second electro-mechanical energy conversion element;
Have
The first and second electro-mechanical energy conversion elements respectively generate alternating voltages that generate vibrations in which the vibrations of the first vibration mode and the second vibration mode having different orders are superimposed on the vibrating body. Applied to
The alternating voltages applied to the first electro-mechanical energy conversion element and the second electro-mechanical energy conversion element respectively have different phases and the same frequency,
When the series resonance frequency of the first inductor and the first capacitor is fs1, the series resonance frequency of the second inductor and the second capacitor is fs2, and the resonance frequency of the vibrating body is fm. In addition,
0.73 · fm <fs1 <1.2 · fm, and 0.73 · fm <fs2 <1.2 · fm
A device characterized by satisfying. A vibrating body comprising: an elastic body; a first electro-mechanical energy conversion element fixed to the elastic body; and a second electro-mechanical energy conversion element;
A drive circuit;
Have
The drive circuit is
A first inductor and a first capacitor connected in series to the first electro-mechanical energy conversion element;
A second inductor and a second capacitor connected in series to the second electro-mechanical energy conversion element;
Have
The vibration body is generated by switching the vibration of the first vibration mode and the vibration of the second vibration mode having different orders in terms of time.
When the series resonance frequency of the first inductor and the first capacitor is fs1, the series resonance frequency of the second inductor and the second capacitor is fs2, and the resonance frequency of the vibrating body is fm. In addition,
0.73 · fm <fs1 <1.2 · fm, and 0.73 · fm <fs2 <1.2 · fm
A device characterized by satisfying. The drive circuit is
A first transformer comprising a first primary coil to which an alternating voltage is applied, and a first secondary coil connected in parallel to the first electromechanical energy conversion element;
A second transformer comprising a second primary coil to which an alternating voltage is applied, and a second secondary coil connected in parallel to the second electro-mechanical energy conversion element;
Have
The first inductor and the first capacitor are connected in series to the first electro-mechanical energy conversion element on at least one of a primary side and a secondary side of the first transformer;
The second inductor and the second capacitor are connected in series to the second electro-mechanical energy conversion element on at least one of the primary side and the secondary side of the second transformer. The apparatus according to claim 1 or 2, characterized in that A vibrating body comprising: an elastic body; a first electro-mechanical energy conversion element fixed to the elastic body; and a second electro-mechanical energy conversion element;
A drive circuit;
Have
The drive circuit is
A first inductor and a first capacitor connected in series to the first electro-mechanical energy conversion element;
A second inductor and a second capacitor connected in series to the second electro-mechanical energy conversion element;
Have
First vibration mode vibrations and second vibration mode vibrations having different orders are generated in the vibration body by switching over time, or vibrations in the first vibration mode having different orders are generated in the vibration body. And applying an alternating voltage for generating a vibration obtained by superimposing the vibrations of the second vibration mode to each of the first and second electro-mechanical energy conversion elements,
Alternations applied to the first electro-mechanical energy conversion element and the second electro-mechanical energy conversion element, respectively, in the case of generating a vibration in which the first and second vibration modes having different orders are superimposed. The voltages have different phases and the same frequency,
When the peak frequency of the alternating voltage applied to the first electro-mechanical energy conversion element and the second electro-mechanical energy conversion element is fe and the drive frequency of the vibrating body is fd,
fe <2 · fd
A device characterized by satisfying. 4. The apparatus according to claim 3, wherein the first inductor and the second inductor are a leakage inductance of the first transformer and a leakage inductance of the second transformer, respectively .   The apparatus according to claim 1, wherein the powder on the vibrating body is driven by generating vibration in the vibrating body.   The apparatus according to claim 6, wherein the powder is dust, and the dust on the vibrating body is driven and removed.   An optical apparatus comprising: the apparatus according to claim 1; and a light receiving element provided at a position where light transmitted through the elastic body of the vibrating body is incident. A driving circuit for a vibrating body that generates vibration in at least a vibrating body including the electro-mechanical energy converting element and the elastic body by applying an alternating voltage to the electromechanical energy converting element fixed to the elastic body Because
A first inductor and a first capacitor connected in series to the first electro-mechanical energy conversion element;
A second inductor and a second capacitor connected in series to the second electro-mechanical energy conversion element;
Have
First vibration mode vibrations and second vibration mode vibrations having different orders are generated in the vibration body by switching over time, or vibrations in the first vibration mode having different orders are generated in the vibration body. And applying an alternating voltage for generating a vibration obtained by superimposing the vibrations of the second vibration mode to each of the first and second electro-mechanical energy conversion elements,
Alternations applied to the first electro-mechanical energy conversion element and the second electro-mechanical energy conversion element, respectively, in the case of generating a vibration in which the first and second vibration modes having different orders are superimposed. The voltages have different phases and the same frequency,
When the peak frequency of the alternating voltage applied to the first electro-mechanical energy conversion element and the second electro-mechanical energy conversion element is fe and the drive frequency of the vibrating body is fd,
fe <2 · fd
A driving circuit for a vibrating body, characterized in that:   The vibration body drive circuit according to claim 9, wherein the vibration body is driven to drive powder on the vibration body.   11. The vibration body driving circuit according to claim 10, wherein the powder is dust, and the dust on the vibration body is driven and removed.   The drive circuit according to any one of claims 9 to 11, a vibrating body driven by the drive circuit, and a light receiving element provided at a position where light transmitted through the elastic body of the vibrating body is incident An optical apparatus comprising: