JPWO2016035707A1 - Drive apparatus and drive method for piezoelectric vibration device - Google Patents

Abstract

Provided are a drive device and a drive method for a piezoelectric vibration device capable of vibrating an object to be vibrated with sufficient strength by a piezoelectric vibration device including a piezoelectric resonator. A driving device for driving the piezoelectric vibration device 1. The piezoelectric resonator 3 includes a drive signal application circuit 22 a that applies an AC drive signal, and a drive frequency sweep circuit 22 b that sweeps the frequency of the AC drive signal within a certain frequency range including the resonance frequency of the piezoelectric resonator 3.

Description

  The present invention relates to a driving device and a driving method for driving a piezoelectric vibration device having a piezoelectric resonator.

  In recent years, mobile phones and wearable terminals have incorporated a vibration source as a means for notifying incoming calls and the like. As such a vibration source, for example, a vibration device described in Patent Document 1 below can be used. The vibration device described in Patent Document 1 uses a piezoelectric resonator. In order to obtain larger vibration, Patent Document 1 discloses a structure in which a weight is fixed to an end portion of a piezoelectric resonator.

WO2009 / 141970A1

  In order to vibrate the body of a mobile phone or wearable terminal and make it sense to a person, it is necessary to better transmit the vibration to the outside of the body. Therefore, it is desirable that the drive frequency of the vibration device is low. For this reason, attempts have been made to fix a weight to the tip of the piezoelectric resonator or to lower the spring property of the metal plate supporting the piezoelectric resonator.

  In addition, when a drive signal having a frequency near the mechanical resonance frequency of the vibration system including the housing is applied instead of the electrical resonance frequency of the piezoelectric resonator, the housing often vibrates most strongly.

  However, it has been found that the driving frequency at which the vibration intensity of the casing is increased changes when the mobile phone or the wearable terminal is placed on the desk, held by hand, or worn on the body. Therefore, even if a drive signal having a certain frequency is applied to vibrate the piezoelectric resonator, the casing cannot be vibrated sufficiently strongly.

  An object of the present invention is to provide a driving device and a driving method for a piezoelectric vibration device that can vibrate an object to be vibrated greatly by a piezoelectric vibration device including a piezoelectric resonator.

  A drive device for a piezoelectric vibration device according to the present invention is a drive device for driving a piezoelectric vibration device including a piezoelectric resonator, and includes a drive signal applying circuit for supplying an AC drive signal to the piezoelectric resonator, and the piezoelectric resonance. A drive frequency sweep circuit that sweeps the frequency of the AC drive signal within a certain frequency range including the resonance frequency of the child.

  In a specific aspect of the piezoelectric vibration device driving device according to the present invention, the housing in which the piezoelectric vibration device is mounted and the amount of vibration applied to the housing due to the vibration of the piezoelectric vibration device are detected. And a sensor that is connected to the sensor and the frequency at which the amount of vibration is maximum is included in the frequency range of the AC drive signal, the drive frequency sweep circuit A control device that sweeps the frequency of the drive signal within the fixed frequency range and, if not included, changes the frequency range of the AC drive signal to a range including a frequency at which the amount of vibration is maximized; Prepare.

  In another specific aspect of the piezoelectric vibration device driving device according to the present invention, the control device changes the frequency range of the AC drive signal to be narrow within a range including a frequency at which the vibration amount is maximum.

  A driving method of a piezoelectric vibration device according to the present invention is a driving method of a piezoelectric vibration device including a piezoelectric resonator, and the piezoelectric vibration is within a certain frequency range including a resonance frequency of a vibration system including the piezoelectric resonator. The frequency of the drive signal applied to the apparatus is swept.

  In a specific aspect of the method for driving a piezoelectric vibration device according to the present invention, a housing in which the piezoelectric vibration device is mounted, and an amount of vibration applied to the housing by vibration of the piezoelectric vibration device in the housing A piezoelectric vibration device driving method further comprising: a sensor for detecting the frequency, wherein the frequency at which the amount of vibration detected from the sensor is maximized is included in the frequency range of the AC drive signal. If the frequency of the drive signal is swept within the fixed frequency range and is not included, the frequency range of the drive signal is changed to a range including a frequency at which the vibration amount is maximum.

  In another specific aspect of the method for driving a piezoelectric vibration device according to the present invention, the frequency range of the AC drive signal is changed to be narrow within a range including a frequency at which the vibration amount is maximum.

  According to the driving device and the driving method of the piezoelectric vibration device according to the present invention, the piezoelectric resonator is swept in order to sweep the frequency of the drive signal within a certain frequency range including the resonance frequency of the vibration system including the piezoelectric resonator and the housing. The object to be vibrated can be vibrated greatly by the piezoelectric vibration device included.

FIG. 1 is a perspective view of a piezoelectric vibration device used in the first embodiment of the present invention. FIG. 2 is a front sectional view of the piezoelectric vibration device used in the first embodiment of the present invention. FIG. 3 is a diagram illustrating the relationship between the frequency of the drive signal in the piezoelectric vibration device according to the first embodiment and the acceleration applied to the housing from the piezoelectric vibration device. FIG. 4 is a schematic configuration diagram of the drive device for the piezoelectric vibration device according to the first embodiment of the present invention. FIG. 5 is a flowchart for explaining a driving method of the piezoelectric vibration device according to the first embodiment of the present invention.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  It should be pointed out that each embodiment described in this specification is an exemplification, and a partial replacement or combination of configurations is possible between different embodiments.

  In the first embodiment of the present invention, the piezoelectric vibration device 1 shown in FIGS. 1 and 2 is driven. The piezoelectric vibration device 1 has an elastic plate 2 made of a metal plate or a synthetic resin plate. The elastic plate 2 has a first elastic plate portion 2a and a second elastic plate portion 2b arranged to face the first elastic plate portion 2a.

  The longitudinal direction of the piezoelectric vibration device 1 is the length direction, and the direction orthogonal to the length direction is the width direction.

  The 1st elastic board part 2a and the 2nd elastic board part 2b are connected by the bending connection part 2c.

  A piezoelectric resonator 3 is provided on the inner surface of the first elastic plate portion 2a. The piezoelectric resonator 3 is composed of a multilayer piezoelectric ceramic vibration element.

  As the piezoelectric resonator 3 expands and contracts, the first elastic plate portion 2a vibrates so as to be displaced between a state extending in the length direction and a state contracting. Along with this, the tip of the first elastic plate portion 2a repeats displacement between a state positioned above and a state positioned below and vibrates.

  A circuit board 9 is attached to the inner surface of the second elastic plate portion 2b. The circuit board 9 forms wiring for supplying a drive signal to the piezoelectric vibration device. Further, a drive circuit that drives the piezoelectric vibration device 1 may be configured together.

  A mass addition member 13 is fixed to the tip of the first elastic plate portion 2a.

  In such a piezoelectric vibration device 1, an AC drive signal is applied to the piezoelectric resonator 3 by the drive device. By the way, when this type of piezoelectric vibration device 1 is used for incoming notification of a mobile phone or a wearable terminal, it vibrates at a relatively low resonance frequency as described above. The resonance frequency of the piezoelectric resonator 3 is 100 Hz or more and 300 Hz or less. Accordingly, the piezoelectric vibration device 1 also resonates in such a low frequency band.

  However, the vibration intensity is not always strongest when a drive signal having an electrical resonance frequency of the piezoelectric vibration device 1 is applied. Actually, it is known that the vibration is strongest when a drive signal near the mechanical resonance frequency is applied.

  In addition, as described above, in a mobile phone or a wearable terminal, the frequency of the drive signal that increases the vibration intensity changes when placed on a desk, held by hand, or worn on the body. Therefore, in a conventional drive device for a piezoelectric vibration device that applies a drive signal having a constant frequency, a sufficient amount of vibration cannot always be given to the housing.

  FIG. 4 is a schematic configuration diagram of a wearable terminal including the piezoelectric vibration device and the driving device thereof according to the first embodiment.

  The wearable terminal 20 has a housing 21. Various circuit components and machine elements constituting the wearable terminal 20 are housed in the housing 21. In FIG. 4, only the portion where the piezoelectric vibration device 1 and its driving device are configured is schematically illustrated. Shown in

  The piezoelectric vibration device 1 is fixed in the housing 21. FIG. 4 shows only the position where the piezoelectric vibration device 1 is provided schematically. When the piezoelectric vibration device 1 vibrates, the housing 21 vibrates in response to the vibration of the piezoelectric vibration device 1. That is, accelerations acting in opposite directions are repeatedly given to the casing 21 by the vibration of the piezoelectric vibration device 1.

  A sensor 23 is built in the housing 21. The sensor 23 is an acceleration sensor provided to detect acceleration applied to the housing 21. The acceleration corresponds to the “vibration amount” of the present invention.

  The sensor 23 is connected to the control device 25, and a signal representing the acceleration detected by the sensor 23 is given to the control device 25.

  On the other hand, the piezoelectric vibration device 1 is connected to a drive circuit 22. The drive circuit 22 includes a drive signal application circuit 22a and a drive frequency sweep circuit 22b. A drive signal application circuit 22 a is electrically connected to the piezoelectric vibration device 1. The drive signal application circuit 22 a applies an AC drive signal to the piezoelectric resonator of the piezoelectric vibration device 1. A drive frequency sweep circuit 22b is connected to the drive signal application circuit 22a. The drive frequency sweep circuit 22b has a function of sweeping the frequency of the drive signal within a certain frequency range including the resonance frequency of the vibration system including the piezoelectric resonator 3 and the housing. As a result, the drive circuit 22 applies an AC drive signal whose frequency is swept within a certain frequency range including the resonance frequency of the vibration system including the piezoelectric resonator 3 and the casing to the piezoelectric resonator of the piezoelectric vibration device 1. can do.

  The drive frequency sweep circuit 22b and the drive signal application circuit 22a are connected to the control device 25. In addition, a memory 24 is connected to the control device 25. The memory 24 stores the above-described certain frequency range in advance.

  With reference to FIG. 5, the drive method in the piezoelectric vibration apparatus of this embodiment is demonstrated.

  Note that when the piezoelectric vibration device 1 is vibrated, acceleration is applied to the casing 21. This acceleration corresponds to the amount of vibration applied to the housing 21. The magnitude of this acceleration varies depending on the driving frequency of the piezoelectric resonator. FIG. 3 is a diagram illustrating an example of the relationship between the frequency of the drive signal of the piezoelectric vibration device 1 and the acceleration of the housing 21. As shown in FIG. 3, it can be seen that the acceleration is the highest when a drive signal having a frequency near 267 Hz is applied. And it turns out that acceleration becomes quite small as it goes away from 267 Hz.

  In this embodiment, the frequency of the drive signal is swept within a certain frequency range. The memory 24 stores a frequency range from 254 Hz to 280 Hz as a constant frequency range. In the present embodiment, the AC drive signal in which the frequency of the drive signal is swept within a certain frequency range is, for example, a chirp wave that changes the frequency with time in the certain frequency range.

  Thus, the optimum vibration can always be generated regardless of the fluctuation of the resonance frequency depending on the state of the piezoelectric vibration device.

  FIG. 5 shows a flowchart for explaining a driving method of the piezoelectric vibration device.

  In step S1, an AC drive signal is applied to the piezoelectric vibration device 1 to vibrate the piezoelectric vibration device 1. More specifically, the control device 25 causes the piezoelectric vibration device 1 to provide an AC drive signal from the drive signal application circuit 22a. As a result, the piezoelectric resonator of the piezoelectric vibration device 1 expands and contracts, and the piezoelectric vibration device 1 vibrates. When the piezoelectric vibration device 1 vibrates, the vibration is transmitted to the casing 21 and acceleration is applied to the casing 21. That is, accelerations in opposite directions are repeatedly given to the casing 21.

  In step S2, the sensor 23 detects the vibration amount of the piezoelectric vibration device 1 such as acceleration. A signal indicating the vibration amount is given to the control device 25.

  In step S <b> 3, the control device 25 determines whether or not the vibration amount is within the range of the target value stored in the memory 24 in advance. That is, when the frequency with the maximum amount of vibration is included in the frequency range of the AC drive signal, the process proceeds to step S4, and the vibration is continued with the drive signal in the frequency range in step S1. In step S3, when the vibration amount is not included in the range of the target value, that is, when the frequency at which the vibration amount is maximum is not included in the frequency range of the AC drive signal, the process proceeds to step S5 and sweeps. The center frequency of the drive signal is changed while keeping the frequency range constant. And it changes to step S1 again and continues a vibration.

  Therefore, according to the driving method of the present embodiment, the piezoelectric resonator can be driven at a frequency at which the amount of vibration applied to the casing 21 is relatively large. Therefore, the object to be vibrated can be greatly vibrated by the piezoelectric vibration device including the piezoelectric resonator.

  Preferably, it is desirable to change the frequency sweep range to be narrow within the range including the frequency at which the acceleration, that is, the vibration amount is maximum. Thereby, the piezoelectric vibration device 1 can be reliably vibrated with an even higher vibration strength.

  In the above embodiment, the sensor 23 and the control device 25 are used. However, in the present invention, such a control device 25 and sensor 23 may not be used. That is, the piezoelectric vibration device 1 may be driven by the drive signal application circuit 22a by repeating the sweep within a certain frequency range by the drive frequency sweep circuit 22b. Even in this case, since the frequency of the drive signal is swept within a certain frequency range, the piezoelectric vibration device 1 is always driven at a frequency with high vibration intensity. Therefore, if the fixed frequency range including the resonance frequency is set within a fixed frequency range in which a sufficient amount of vibration is obtained, the piezoelectric vibration device 1 can be vibrated with high vibration strength without using the control device 25. Can do.

  For example, when it is required in advance that variations and fluctuations in the resonance frequency are within ± 10 Hz, the drive signal may be given to the piezoelectric resonator while sweeping the frequency of the drive signal in a frequency range including the resonance frequency. .

  The drive frequency sweep circuit and the drive signal application circuit may each be incorporated in the control circuit or the piezoelectric vibration device.

  In the above embodiment, the sensor 23 is an acceleration sensor, and the acceleration is detected as the vibration amount. However, the vibration amount may be detected by using a diaphragm for a sound generation component, or the vibration amount may be an acceleration. You may detect using the distortion amount of a housing other than.

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibration apparatus 2 ... Elastic board 2a ... 1st elastic board part 2b ... 2nd elastic board part 2c ... Bending connection part 3 ... Piezoelectric resonator 9 ... Circuit board 13 ... Mass addition member 20 ... Wearable terminal 21 ... Housing 22 ... Drive circuit 22a ... Drive signal application circuit 22b ... Drive frequency sweep circuit 23 ... Sensor 24 ... Memory 25 ... Control device

Claims (6)

A driving device for driving a piezoelectric vibration device including a piezoelectric resonator,
A drive signal applying circuit for applying an AC drive signal to the piezoelectric resonator;
A drive device for a piezoelectric vibration device, comprising: a drive frequency sweep circuit that sweeps a frequency of the AC drive signal within a certain frequency range including a resonance frequency of the piezoelectric resonator. A housing in which the piezoelectric vibration device is mounted;
A sensor provided in the housing to detect the amount of vibration applied to the housing by vibration of the piezoelectric vibration device;
When the frequency that is connected to the sensor and has the maximum amount of vibration is included in the frequency range of the AC drive signal, the frequency of the drive signal is within the fixed frequency range by the drive frequency sweep circuit. 2. The piezoelectric vibration device according to claim 1, further comprising: a control device that sweeps the frequency range of the AC drive signal to a range that includes a frequency at which the vibration amount is maximum when the frequency range is not included. Drive device.   The drive device for a piezoelectric vibration device according to claim 2, wherein the control device changes the frequency range of the AC drive signal to be narrow within a range including a frequency at which the vibration amount is maximum. A method of driving a piezoelectric vibration device including a piezoelectric resonator,
A method for driving a piezoelectric vibration device, wherein a frequency of a drive signal applied to the piezoelectric vibration device is swept within a certain frequency range including a resonance frequency of a vibration system including the piezoelectric resonator. A method for driving a piezoelectric vibration device, further comprising: a housing in which the piezoelectric vibration device is mounted; and a sensor that detects a vibration amount applied to the housing by vibration of the piezoelectric vibration device in the housing. ,
When the frequency at which the vibration amount detected from the sensor is maximized is included in the frequency range of the AC drive signal, the frequency of the drive signal is swept within the fixed frequency range. 5. The method of driving a piezoelectric vibration device according to claim 4, wherein if there is not, the frequency range of the drive signal is changed to a range including a frequency at which the vibration amount is maximum.   The method for driving a piezoelectric vibration device according to claim 5, wherein the frequency range of the AC drive signal is changed to be narrow within a range including a frequency at which the vibration amount is maximum.

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