JP2011143099A - Vibration element driving circuit and vibration element protection circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration element driving circuit and a vibration element protection circuit, capable of protecting a vibration element from excessive excitation by a simple structure. <P>SOLUTION: The vibration element driving circuit includes: a first filter part 110 for receiving an input signal S0 and outputting a signal component of a relatively low first frequency range of the signal; a second filter part 120 for receiving the input signal S0 and outputting a signal component of a second frequency range higher than the first frequency range of the signal; an addition part 130 for adding an output signal S1 from the first filter part 110 and an output signal S2 from the second filter part 120; and a driving part 140 for generating a driving signal S4 by power-amplifying an output signal S3 from the addition circuit 130. The first filter part 110 and the second filter part 120 are configured so that their respective output signals are in opposite phases from each other in a frequency approximate to the resonance frequency of the vibration element 150. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vibration element drive circuit for driving a vibration element constituting an electro-mechanical conversion unit in, for example, a drive unit for a specific element in an imaging apparatus, a beauty instrument that applies vibration to human skin, or an acoustic device. And a vibration element protection circuit for protecting these vibration elements from excessive excitation.

A vibration element including an electromechanical conversion unit is incorporated in various devices such as an imaging device, a beauty tool, or an acoustic device, and constitutes an important movable part in these devices.
Each of the above-described vibration elements has a unique resonance frequency, and depending on the device, the resonance phenomenon is actively used to contribute to improvement of conversion efficiency in electro-mechanical conversion.
On the other hand, the resonance phenomenon in the electro-mechanical conversion element sometimes induces excessive excitation to hinder desired characteristics, and further has a risk of causing failure or destruction of the device.

In particular, in the case of an application in which the vibration element is output to the vicinity of its absolute rating, it is necessary to sufficiently consider the phenomenon that is likely to lead to the fear as described above.
In order to avoid the above-mentioned concerns in a wiper drive device required for a small digital camera or the like, there has already been proposed a technique for detecting an amplitude of mechanical vibration in an electro-mechanical conversion element to avoid excessive excitation. (For example, refer to Patent Document 1).

  Alternatively, a specially shaped application with an opening in the center to prevent false detection of the loaded state and unloaded state by suppressing unnecessary parasitic resonance in the applicator head of a beauty device that vibrates the human skin. A technique using a head is already proposed (see, for example, Patent Document 2).

JP 2005-204394 A Japanese Patent No. 4165562

However, in the technique disclosed in Patent Document 1, it is essential to use a means for detecting the amplitude of mechanical vibration in the electromechanical conversion element, and excessive excitation is avoided based on the detection output by the means. I have to. Therefore, the problem that the complication of the apparatus cannot be avoided is caused.
In addition, the technique disclosed in Patent Document 2 is required to make the structure of the vibration element itself special, and does not attempt to eliminate the adverse effects due to parasitic resonance on the vibration element drive circuit side.
The present invention has been made in view of the above situation, and an object thereof is to provide a vibration element driving circuit and a vibration element protection circuit that can protect a vibration element from excessive excitation with a simple configuration. .

In order to achieve the above object, the following technologies are proposed.
(1) A vibration element drive circuit for generating a drive signal for driving a mechanical vibration element,
A first filter unit that receives an input signal and outputs a signal component of a relatively low first frequency range;
A second filter unit that receives the input signal and outputs a signal component of a second frequency range that is relatively higher than the first frequency range;
An adding unit for adding the output signal of the first filter unit and the output signal of the second filter unit;
A drive unit that generates the drive signal based on the output signal of the adder,
The vibration element characterized in that the first filter section and the second filter section are configured such that their output signals are in opposite phases at a frequency near the resonance frequency of the vibration element. Driving circuit.

  In the vibration element driving circuit of (1), the first filter unit and the second filter unit have their output signals in opposite phases at frequencies near the resonance frequency of the vibration element. Each output of the first filter unit and the second filter unit acts differentially in the adding unit, and as a result, a notch filter characteristic that attenuates the signal level of the frequency component near the resonance frequency of the vibration element. Presents.

(2) A filter characteristic adjustment circuit that adjusts a filter characteristic of at least one of the first filter unit and the second filter unit in accordance with a value of a resonance frequency of the vibration element is provided. The vibration element driving circuit according to (1).
(3) The vibration element drive circuit according to (1), wherein the first filter section is a primary low-pass filter, and the second filter section is a secondary high-pass filter.
(4) The vibration element driving circuit according to (1), wherein the first filter unit is a secondary band-pass filter, and the second filter unit is a secondary high-pass filter.
(5) The vibration element driving circuit according to (1), wherein the first filter unit is a secondary low-pass filter, and the second filter unit is a primary high-pass filter.
(6) The vibration element driving circuit according to (1), wherein the first filter unit is a secondary low-pass filter, and the second filter unit is a secondary high-pass filter.

(7) A vibration element protection circuit for protecting a mechanical vibration element driven by a drive signal generated from an input signal from being excessively excited,
A first filter unit that receives the input signal and outputs a signal component of a relatively low first frequency range;
A second filter unit that receives the input signal and outputs a signal component of a second frequency range that is relatively higher than the first frequency range;
An addition unit for adding the output signal of the first filter unit and the output signal of the second filter unit;
The vibration element characterized in that the first filter section and the second filter section are configured such that their output signals are in opposite phases at a frequency near the resonance frequency of the vibration element. Protection circuit.

  In the vibration element protection circuit of (7), the first filter unit and the second filter unit have their output signals in opposite phases at frequencies near the resonance frequency of the vibration element. Each output of the first filter unit and the second filter unit acts differentially in the adding unit, and as a result, a notch filter characteristic that attenuates the signal level of the frequency component near the resonance frequency of the vibration element. Presents.

(8) A filter characteristic adjustment circuit that adjusts a filter characteristic of at least one of the first filter unit and the second filter unit in accordance with a value of a resonance frequency of the vibration element is provided. The vibration element protection circuit according to (7).
(9) The vibration element protection circuit according to (7), wherein the first filter unit is a primary low-pass filter, and the second filter unit is a secondary high-pass filter.
(10) The vibration element protection circuit according to (7), wherein the first filter unit is a secondary band-pass filter, and the second filter unit is a secondary high-pass filter.
(11) The vibration element protection circuit according to (7), wherein the first filter unit is a secondary low-pass filter, and the second filter unit is a primary high-pass filter.
(12) The vibration element protection circuit according to (7), wherein the first filter unit is a secondary low-pass filter, and the second filter unit is a secondary high-pass filter.

  A vibration element driving circuit and a vibration element protection circuit capable of protecting a vibration element from excessive excitation with a simple configuration that does not require other elements such as a detection element other than a circuit for driving the vibration element are realized. be able to.

It is a block diagram showing the vibration element drive circuit and vibration element protection circuit which are embodiments of the present invention. It is a figure showing the frequency-impedance characteristic of the vibration element driven by the vibration element drive circuit of this invention. It is a figure showing the frequency-phase characteristic of each filter part and addition part in the vibration element drive circuit and vibration element protection circuit of FIG. FIG. 2 is a diagram illustrating frequency-gain characteristics of each filter unit and addition unit in the vibration element driving circuit and the vibration element protection circuit of FIG. 1. It is a figure showing 1st Example of the vibration element protection circuit of this invention. It is a figure showing 2nd Example of the vibration element protection circuit of this invention. It is a figure showing the 3rd Example of the vibration element protection circuit of the present invention. It is a figure showing 4th Example of the vibration element protection circuit of this invention. It is a block diagram showing the vibration element protection circuit which is other embodiment of this invention.

Hereinafter, the present invention will be clarified by describing embodiments of the present invention in detail with reference to the drawings.
(Embodiments of vibration element driving circuit and vibration element protection circuit)
FIG. 1 is a block diagram showing a vibration element driving circuit and a vibration element protection circuit according to an embodiment of the present invention.
The vibration element driving circuit 10 includes a first filter unit 110, a second filter unit 120, an adding unit 130, and a driving unit 140.
The first filter unit 110 and the second filter unit 120 receive the input signal S0 from the common input terminal 101, respectively.
The output signal S1 of the first filter unit 110 and the output signal S2 of the second filter unit 120 are input to the adder unit 130, and an output signal S3 is obtained from the adder unit 130.

  The output signal S3 is input to the drive unit 140, and the drive signal S4 is generated. Here, the driving unit 140 may amplify the output signal S3 with a predetermined amplification factor. An amplifying unit for amplifying the output signal S3 may be provided after the adding unit 130, and amplification for amplifying the output signal after one of the first filter unit 110 and the second filter unit 120. May be provided, or may be provided downstream of both the first filter unit 110 and the second filter unit 120.

This drive signal S4 is supplied to the vibration element 150, and the vibration element 150 is excited. Examples of the vibration element 150 include a piezoelectric actuator, a medical examination probe, and a mobile device speaker.
The vibration element protection circuit 11 is configured by the first filter unit 110, the second filter unit 120, and the addition unit 130 in the vibration element driving circuit 10 described above.

The first filter unit 110 is configured to have a filter characteristic that allows a low-frequency to pass through relative to the second filter unit 120. For example, a low pass filter and a band pass filter can be mentioned.
The second filter unit 120 is configured to have a filter characteristic that allows a high frequency to pass through relative to the first filter unit 110. For example, a high pass filter and a band pass filter can be mentioned.
The first filter unit 110 and the second filter unit 120 are configured such that their output signals are in opposite phases at a frequency near the resonance frequency f0 of the vibration element 150. Here, the opposite phase means that each output signal has a phase difference of 180 degrees or close thereto.

FIG. 2 is a diagram qualitatively representing the frequency-impedance characteristics of the vibration element 150. In FIG. 2, the horizontal axis corresponds to the frequency, and the vertical axis corresponds to the impedance at the input end of the vibration element 150.
The impedance exhibits a peak at a substantially central frequency in the illustrated frequency range, and the vicinity of this frequency corresponds to the mechanical resonance point (resonance frequency f0) of the vibration element 150. In the mechanical resonance frequency or in the vicinity thereof, if no measures are taken, the vibration element 150 exhibits an overexcited state, which may cause deterioration or failure, and possibly breakage.

FIG. 3 is a diagram illustrating frequency-phase characteristics of each filter unit and addition unit in the vibration element driving circuit 10 (vibration element protection circuit 11) of FIG.
In FIG. 3, the horizontal axis corresponds to the frequency, and the vertical axis corresponds to the phase. And the output signal S1 of the 1st filter part 110 of FIG. 1 is represented with the dashed-dotted line, and the output signal S2 of the 2nd filter part 120 is represented with the broken line.
As shown in the figure, since either of the signals S1 and S2 is dominant in the relatively low frequency region and the relatively high frequency region, the phase difference between them can be ignored.
On the other hand, in the region near the resonance frequency f0, the signals S1 and S2 have a phase difference of 180 degrees (ie, opposite phase), and the addition in the adder 130 is effectively differential (subtraction). . This means that the signal S3 that is the sum of the signals S1 and S2 is most attenuated in the vicinity of the resonance frequency f0, and therefore, excessive excitation as described above is effectively avoided.

FIG. 4 is a diagram illustrating frequency-gain characteristics of each filter unit and addition unit in the vibration element driving circuit 10 (vibration element protection circuit 11) of FIG.
In FIG. 4, the horizontal axis corresponds to the frequency, and the vertical axis corresponds to the gain. The output signal S1 of the first filter unit 110 in FIG. 1 is represented by a one-dot chain line, the output signal S2 of the second filter unit 120 is represented by a broken line, and the output signal S3 of the addition unit 130 is represented by a solid line.

From FIG. 4, it can be easily understood that the characteristic that the signal S3, which is the sum of the signals S1 and S2, is attenuated in the vicinity of the resonance frequency f0 is remarkable.
That is, according to the vibration element drive circuit 10 (vibration element protection circuit 11) of the present invention, a characteristic is obtained in which the gain related to the drive signal S3 for exciting the vibration element 150 in the region near the resonance frequency f0 is minimized. Accordingly, excessive excitation in the vicinity of the resonance frequency region is suppressed.

As understood from the characteristics shown in FIGS. 3 and 4, according to the vibration element driving circuit 10 (vibration element protection circuit 11) of the present invention, the input signal is attenuated in the vicinity of the resonance frequency f0. Is effectively the same as the characteristic of the notch filter (band elimination filter) that attenuates the signal in the vicinity of the resonance frequency f0.
In other words, according to the vibration element drive circuit 10 (vibration element protection circuit 11) of the present invention, a frequency range of a certain design value related to the input signal (in the above example), despite the extremely simple configuration. Input / output characteristics are realized that attenuate signals in the vicinity of f0) and transmit signals in other frequency ranges.

For example, an electro-mechanical-acoustic conversion element (a transducer in which a small sounding body that generates a bell sound and a speaker is integrated) has a vibration element driving circuit 10 (vibration element protection circuit 11) exhibiting such notch filter characteristics as a vibration element. ), Etc., it is possible to realize an ideal musical sound reproducing device that reproduces high-quality musical sounds and does not cause deterioration or failure of the transducer due to overexcitation in the region near the resonance frequency. Become.
(Example of a vibration element protection circuit as one embodiment)

FIG. 5 is a diagram illustrating a first embodiment of the vibration element protection circuit according to the present invention. 5A is a circuit diagram showing the first embodiment, FIG. 5B is a diagram showing frequency-gain characteristics regarding the circuit of FIG. 5A, and FIG. 5C is a diagram of FIG. 5A. It is a figure showing the frequency-phase characteristic regarding a circuit.
The vibration element protection circuit 51 in FIG. 5A includes a first filter unit 510, a second filter unit 520, and an addition unit 530.

The first filter unit 510 and the second filter unit 520 receive the input signal S50 from the common input terminal 501, respectively.
The first filter unit 510 is a primary low-pass filter, and the second filter unit 520 is a secondary high-pass filter. The output signal S51 of the first filter unit 510 and the output signal S52 of the second filter unit 520 are input to the adding unit 530 and output signal S53 from the output terminal 502 of the vibration element protection circuit 51 which is the output terminal of the adding unit 530. Get.
The vibration element is excited by a drive signal obtained by power amplification of the output signal S53.

In FIGS. 5B and 5C, the signal S51 is represented by a one-dot chain line, the signal S52 is represented by a broken line, and the signal S53 is represented by a solid line.
As can be easily understood from FIGS. 5B and 5C, the signals S51 and S52 have a phase difference of approximately 180 degrees in the vicinity of the resonance frequency f0, that is, have an opposite phase relationship, and the frequency The characteristic that the signal S53, which is the sum of both signals, attenuates in the region near f0 is remarkable. That is, it can be seen that a notch filter characteristic having a very steep attenuation characteristic is realized in the vicinity of the frequency f0.

FIG. 6 is a diagram illustrating a second embodiment of the vibration element protection circuit according to the present invention. 6A is a circuit diagram illustrating the first embodiment, FIG. 6B is a diagram illustrating frequency-gain characteristics regarding the circuit of FIG. 6A, and FIG. 6C is a diagram of FIG. 6A. It is a figure showing the frequency-phase characteristic regarding a circuit.
The vibration element protection circuit 61 in FIG. 6A includes a first filter unit 610, a second filter unit 620, and an addition unit 630.

The first filter unit 610 and the second filter unit 620 receive an input signal S60 from a common input terminal 601.
The first filter unit 610 is a secondary band-pass filter, and the second filter unit 620 is a secondary high-pass filter. The output signal S61 of the first filter unit 610 and the output signal S62 of the second filter unit 620 are input to the adder 630 and output signal S63 from the output terminal 602 of the vibration element protection circuit 61 that is the output terminal of the adder 630. Get.
The vibration element is excited by a drive signal obtained by power amplification of the output signal S63.

In FIGS. 6B and 6C, the signal S61 is represented by a one-dot chain line, the signal S62 is represented by a broken line, and the signal S63 is represented by a solid line.
As can be easily understood from FIGS. 6B and 6C, the signals S61 and S62 have a phase difference close to 180 degrees in the vicinity of the resonance frequency f0, that is, have an opposite phase relationship, and the frequency The characteristic that the signal S63, which is the sum of both signals, attenuates in the vicinity of f0 is remarkable. That is, it can be seen that a notch filter characteristic having a relatively steep attenuation characteristic near the frequency f0 is realized.

FIG. 7 is a diagram illustrating a third embodiment of the vibration element protection circuit according to the present invention. 7A is a circuit diagram showing the first embodiment, FIG. 7B is a diagram showing frequency-gain characteristics regarding the circuit of FIG. 7A, and FIG. 7C is a diagram of FIG. 7A. It is a figure showing the frequency-phase characteristic regarding a circuit.
The vibration element protection circuit 71 in FIG. 7A includes a first filter unit 710, a second filter unit 720, and an addition unit 730.

The first filter unit 710 and the second filter unit 720 receive an input signal S70 from a common input terminal 701, respectively.
The first filter unit 710 is a secondary low-pass filter, and the second filter unit 720 is a primary high-pass filter. The output signal S71 of the first filter unit 710 and the output signal S72 of the second filter unit 720 are input to the adder 730 and output from the output terminal 702 of the vibration element protection circuit 71 that is the output terminal of the adder 730. Get.
The vibration element is excited by a drive signal obtained by power amplification of the output signal S73.

In FIG. 7B and FIG. 7C, the signal S71 is represented by a one-dot chain line, the signal S72 is represented by a broken line, and the signal S73 is represented by a solid line.
As can be easily understood from FIGS. 7B and 7C, the signals S71 and S72 have a phase difference of approximately 180 degrees in the vicinity of the resonance frequency f0, that is, have an opposite phase relationship, and the frequency The characteristic that the signal S73, which is the sum of both signals, attenuates in the region near f0 is remarkable. That is, it can be seen that a notch filter characteristic having a very steep attenuation characteristic in the vicinity of the frequency f0 is realized as in the first embodiment of FIG.

FIG. 8 is a diagram illustrating a fourth embodiment of the vibration element protection circuit according to the invention. 8A is a circuit diagram showing the first embodiment, FIG. 8B is a diagram showing frequency-gain characteristics regarding the circuit of FIG. 8A, and FIG. 8C is FIG. 8A. It is a figure showing the frequency-phase characteristic regarding a circuit.
The vibration element protection circuit 81 in FIG. 8A includes a first filter unit 810, a second filter unit 820, and an addition unit 830.

The first filter unit 810 and the second filter unit 820 receive an input signal S80 from a common input terminal 801, respectively.
The first filter unit 810 is a secondary low-pass filter, and the second filter unit 820 is a secondary high-pass filter. The output signal S81 of the first filter unit 810 and the output signal S82 of the second filter unit 820 are input to the adder 830 and output signal S83 from the output terminal 802 of the vibration element protection circuit 81 that is the output terminal of the adder 830. Get.
The vibration element is excited by a drive signal obtained by power amplification of the output signal S83.

In FIGS. 8B and 8C, the signal S81 is represented by a one-dot chain line, the signal S82 is represented by a broken line, and the signal S83 is represented by a solid line.
As can be easily understood from FIGS. 8B and 8C, the signals S81 and S82 slightly deviate from 180 degrees in the vicinity of the resonance frequency f0, but there is a phase difference close to 180 degrees, that is, opposite phases. The signal S83 that is the sum of both signals attenuates in the vicinity of the frequency f0. That is, it can be seen that a notch filter characteristic having a characteristic of attenuating a relatively large amount of the input signal near the frequency f0 is realized.
In the fourth embodiment shown in FIG. 8, since both the first filter unit 810 and the second filter unit 820 are second-order filters, it is relatively easy to coordinately adjust the Q of both filters. Therefore, it is easy to adjust the shape of the notch filter characteristic.

In the embodiment described above, the circuit constants such as the order of the first filter unit and the second filter unit, the resistance value and the capacitance value of each circuit are selected so as to correspond to the resonance characteristics of the applied vibration element. By adjusting the cutoff frequency or the center frequency and the Q value of the first filter unit and the second filter unit and determining the shape (frequency, sharpness, depth) of the notch, the vibration element is caused by overexcitation. It is possible to realize a notch filter characteristic that is well suited for use in protecting from deterioration and failure. Further, an amplification unit for amplifying the output signal is provided at the subsequent stage of the first filter unit and the second filter unit, respectively, and the gain in the low frequency region and the high frequency region is lowered or increased by changing each amplification factor. You can also.
In the above-described embodiment, the first filter unit and the second filter unit are configured with a second-order or lower filter, but may be configured with a third-order or higher filter. When the filter is composed of a second-order or higher filter, the Q value of the filter can be adjusted, so that the sharpness of the notch can be changed.

(Vibration element protection circuit as another embodiment)
FIG. 9 is a block diagram showing a vibration element protection circuit according to another embodiment of the present invention.
The vibration element protection circuit 91 in FIG. 9 includes a first filter unit 910, a second filter unit 920, and an addition unit 930.
The first filter unit 910 and the second filter unit 920 receive the input signal S90 from the common input terminal 901, respectively.
The first filter unit 910 is a low pass filter or a band pass filter, and the second filter unit 920 is a high pass filter or a band pass filter.

The output signal S91 of the first filter unit 910 and the output signal S92 of the second filter unit 920 are input to the adder unit 930 and output from the output terminal 902 of the vibration element protection circuit 91 that is the output terminal of the adder unit 930. Get.
The vibration element is excited by a drive signal obtained by power amplification of the output signal S93.
In the above, in the vibration element protection circuit 91 of FIG. 9, especially the filter characteristic adjustment for adjusting the filter characteristics of the first filter unit 910 and the second filter unit 920 in accordance with the value of the resonance frequency of the applied vibration element. A circuit 960 is provided.

The resistance values and capacitance values of the resistors and capacitors constituting the circuits of the first filter unit 910 and the second filter unit 920 are variable, and the filter characteristic adjustment circuit 960 changes the resistance value and the capacitance value. Control signal is generated.
Therefore, the circuit constants such as the resistance value and the capacitance value of each circuit of the first filter unit 910 and the second filter unit 920 are changed by the filter characteristic adjustment circuit 960 so as to correspond to the resonance characteristics of the applied vibration element. By adjusting the cut-off frequency or center frequency of the first filter unit 910 and the second filter unit 920, the Q value, etc., and changing the shape of the notch (frequency, sharpness, depth), the vibration element is passed. It is possible to realize a notch filter characteristic that is well suited for applications such as protection from deterioration or failure due to excitation.

In addition, even if the resonance characteristics of the vibration element may change due to secular change or the like, the first filter unit 910 and the second filter unit 920 are made to follow the change adaptively to change the vibration element. Full protection is possible.
In addition, you may comprise so that the filter characteristic of at least any one of the 1st filter part 910 and the 2nd filter part 920 may be adjusted.

10 ………………………………………………………… Vibration element drive circuit 11, 51, 61, 71, 81, 91 ... ……………… Vibration element protection circuit 101 , 501, 601, 801, 901,..., Input terminals 110, 510, 610, 710, 810, 910..., First filter section 120, 520, 620, 720, 820, 920. , 630, 730, 830, 930... Addition unit 140... ………………… Vibration elements 501, 601, 701, 801, 901 …………… Output terminal 960 ………………………………………………………… Filter characteristic adjustment circuit

Claims (12)

A vibration element drive circuit for generating a drive signal for driving a mechanical vibration element,
A first filter unit that receives an input signal and outputs a signal component of a relatively low first frequency range;
A second filter unit that receives the input signal and outputs a signal component of a second frequency range that is relatively higher than the first frequency range;
An adding unit for adding the output signal of the first filter unit and the output signal of the second filter unit;
A drive unit that amplifies the output signal of the addition unit to generate the drive signal;
The vibration element characterized in that the first filter section and the second filter section are configured such that their output signals are in opposite phases at a frequency near the resonance frequency of the vibration element. Driving circuit.   The filter characteristic adjustment circuit which adjusts the filter characteristic of at least any one of said 1st filter part and said 2nd filter part according to the value of the resonant frequency of said vibration element, It is characterized by the above-mentioned. 1 vibration element driving circuit;   2. The vibration element driving circuit according to claim 1, wherein the first filter unit is a first-order low-pass filter, and the second filter unit is a second-order high-pass filter.   2. The vibration element driving circuit according to claim 1, wherein the first filter unit is a secondary band-pass filter, and the second filter unit is a secondary high-pass filter.   2. The vibration element driving circuit according to claim 1, wherein the first filter unit is a secondary low-pass filter, and the second filter unit is a primary high-pass filter.   2. The vibration element driving circuit according to claim 1, wherein the first filter unit is a secondary low-pass filter, and the second filter unit is a secondary high-pass filter. A vibration element protection circuit for protecting a mechanical vibration element driven by a drive signal generated from an input signal from being excessively excited,
A first filter unit that receives the input signal and outputs a signal component of a relatively low first frequency range;
A second filter unit that receives the input signal and outputs a signal component of a second frequency range that is relatively higher than the first frequency range;
An addition unit for adding the output signal of the first filter unit and the output signal of the second filter unit;
The vibration element characterized in that the first filter section and the second filter section are configured such that their output signals are in opposite phases at a frequency near the resonance frequency of the vibration element. Protection circuit.   The filter characteristic adjustment circuit which adjusts the filter characteristic of at least any one of said 1st filter part and said 2nd filter part according to the value of the resonant frequency of said vibration element, It is characterized by the above-mentioned. 7 vibration element protection circuit;   8. The vibration element protection circuit according to claim 7, wherein the first filter unit is a primary low-pass filter, and the second filter unit is a secondary high-pass filter.   8. The vibration element protection circuit according to claim 7, wherein the first filter unit is a secondary band-pass filter, and the second filter unit is a secondary high-pass filter.   8. The vibration element protection circuit according to claim 7, wherein the first filter unit is a secondary low-pass filter, and the second filter unit is a primary high-pass filter.   8. The vibration element protection circuit according to claim 7, wherein the first filter unit is a secondary low-pass filter, and the second filter unit is a secondary high-pass filter.

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