JP2012217040A - Oscillation device and portable terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oscillation device which is capable of improves the sound pressure level while achieving downsizing.SOLUTION: An oscillation device 100 includes: a piezoelectric vibrator 10; a vibration member 20 for restricting the piezoelectric vibrator 10 on one surface and partially including a piezoelectric material 24; and a support member 30 for supporting an edge of the vibration member 20. The vibration member for restricting the piezoelectric vibrator on the one surface partially includes the piezoelectric material. Thus, the oscillation device, capable of improving the sound pressure level while achieving downsizing, is provided.

Description

  The present invention relates to an oscillation device having a piezoelectric vibrator and a portable terminal device.

  Along with miniaturization of portable terminal devices and the like, miniaturization is also required for electroacoustic transducers mounted thereon. As a technique related to miniaturization of the electroacoustic transducer, for example, there is one described in Patent Document 1. The technology described in Patent Document 1 is such that a speaker diaphragm provided on a screen of a portable device and a holding unit that holds the diaphragm are connected by a connecting unit.

  As an electroacoustic transducer, there is a piezoelectric electroacoustic transducer using a piezoelectric vibrator. Piezoelectric electroacoustic transducers generate vibration amplitude using the expansion and contraction of a piezoelectric vibrator. For this reason, it becomes advantageous for thickness reduction compared with the electrodynamic electroacoustic transducer comprised from a magnet, a voice coil, etc. As a technique regarding the piezoelectric type electroacoustic transducer, for example, there are those described in Patent Documents 2 to 5.

  The technique described in Patent Document 2 is to hold a thin-film vibration film in contact with a piezoelectric element by a base. The technique described in Patent Document 3 is such that the planar shape of a piezoelectric diaphragm housed in a case welded by ultrasonic welding is substantially rectangular. The techniques described in Patent Documents 4 and 5 relate to a method of manufacturing a piezoelectric speaker having a piezoelectric sheet formed by filling a resin material between a plurality of arranged piezoelectric elements.

JP 2006-319833 A JP 2004-282221 A Japanese Patent Laid-Open No. 10-200994 JP 2003-348692 A JP 2000-324598 A

  As electronic equipment is downsized, it is desirable to reduce the size of an oscillation device mounted on the electronic equipment. On the other hand, when the oscillation device is downsized, it is difficult to improve the sound pressure level. Therefore, there is a demand for an oscillation device that can improve the sound pressure level while reducing the size.

According to the present invention, a piezoelectric vibrator;
A vibration member that constrains the piezoelectric vibrator in one surface and partially includes a piezoelectric material;
A support member for supporting an edge of the vibration member;
An oscillation device is provided.

  According to the present invention, a portable terminal device equipped with the above-described oscillation device is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the oscillation apparatus which can aim at the improvement of a sound pressure level can be provided, aiming at size reduction.

It is sectional drawing which shows the oscillation apparatus which concerns on this embodiment. It is a perspective view which shows the vibration member shown in FIG. FIG. 8 is a cross-sectional view illustrating a modification of the oscillation device illustrated in FIG. 1. It is a graph which shows the change of the electromechanical coupling coefficient and the mechanical quality coefficient with respect to the weight ratio of a piezoelectric material and a resin material.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

  FIG. 1 is a cross-sectional view showing an oscillation device 100 according to this embodiment. The oscillation device 100 according to this embodiment includes a piezoelectric vibrator 10, a vibration member 20, and a support member 30. The oscillation device 100 is mounted on a mobile terminal device such as a mobile phone.

  The vibration member 20 restrains the piezoelectric vibrator 10 on one surface. Further, the vibration member 20 partially includes the piezoelectric material 24. The support member 30 supports the edge of the vibration member 20. Hereinafter, the configuration of the oscillation device 100 will be described in detail.

The piezoelectric vibrator 10 is made of a piezoelectric material having a piezoelectric effect, and is made of, for example, lead zirconate titanate (PZT) or barium titanate (BaTiO ₃ ) as a material having high electromechanical conversion efficiency. The thickness of the piezoelectric vibrator 10 is preferably 10 μm to 1 mm. When the thickness is less than 10 μm, the piezoelectric vibrator 10 is made of a brittle material, and thus is easily damaged during handling. On the other hand, when the thickness exceeds 1 mm, the electric field strength of the piezoelectric vibrator 10 is reduced. For this reason, the energy conversion efficiency is reduced.
The piezoelectric vibrator 10 is polarized in the thickness direction (vertical direction in FIG. 1). The piezoelectric vibrator 10 has, for example, a circle or an ellipse in a plane direction parallel to one surface of the vibration member 20.

FIG. 2 is a perspective view showing the vibration member 20 shown in FIG. 1 and shows a part of the vibration member 20. As shown in FIGS. 1 and 2, the vibration member 20 includes a resin material 22, and the piezoelectric material 24 is arranged in a matrix in a plane direction parallel to one surface of the vibration member 20 in the resin material 22 as a base material. It is formed by arranging. In this case, the piezoelectric materials 24 arranged in a matrix are provided so as to penetrate the vibration member 20 from the upper surface to the lower surface. Further, at least a part of the piezoelectric material 24 is provided so as to overlap with the piezoelectric vibrator 10 in a plan view.
For example, in the resin material 22, the piezoelectric material 24 is arranged in about 4 to 8 rows in both the x direction and the y direction perpendicular to the x direction. At this time, a plurality of piezoelectric materials 24 are arranged separately from each other in the resin material 22. In addition, the space | interval between the adjacent piezoelectric materials 24 among several piezoelectric materials 24 is 5 mm or less, for example.
As the resin material 22, for example, polyethylene terephthalate, polyethylene, urethane, or the like is used. As the piezoelectric material 24, for example, lead zirconate titanate (PZT) or barium titanate (BaTiO ₃ ) is used as in the piezoelectric vibrator 10.

Since the vibration member 20 includes the resin material 22 having a high internal loss, the mechanical quality factor of the oscillation device 100 can be reduced. Thereby, the frequency characteristic of the sound pressure level can be flattened. In addition, since the vibration member 20 includes the resin material 22, the mechanical strength of the oscillation device 100 can be improved.
Further, in the vibration member 20, the piezoelectric material 24 is formed in a matrix in the resin material 22 that is a base material. Thereby, it can suppress that the vibration amplitude of the vibration member 20 resulting from the high rigidity which the piezoelectric material 24 has is reduced. Therefore, a sufficient sound pressure level can be ensured.

  FIG. 4 is a graph showing changes in the electromechanical coupling coefficient and the mechanical quality coefficient with respect to the weight ratio between the piezoelectric material and the resin material. The weight ratio of the piezoelectric material 24 to the resin material 22 is preferably 1/100 or more and 1/3 or less. When the weight ratio of the piezoelectric material 24 to the resin material 22 is 1/100 or more and 1/3 or less, it corresponds to the optimum region shown in FIG. That is, when the weight ratio of the piezoelectric material 24 to the resin material 22 is 1/100 or more, a sufficient electromechanical coupling coefficient can be obtained. For this reason, it is possible to ensure a sufficient sound pressure level of the oscillation device 100. Further, when the weight ratio of the piezoelectric material 24 to the resin material 22 is 1/3 or less, the mechanical quality factor can be reduced. For this reason, it is possible to sufficiently flatten the acoustic characteristics.

As illustrated in FIG. 1, the oscillation device 100 includes an electrode 72, an electrode 76, and an electrode 78. The electrode 72 is provided on the upper surface of the piezoelectric vibrator 10. The electrode 76 is integrally formed on the upper surface of the vibration member 20 and is sandwiched between the piezoelectric vibrator 10 and the vibration member 20. The electrode 78 is integrally formed on the lower surface of the vibration member 20.
That is, the piezoelectric vibrator 10 is sandwiched between the electrode 72 and the electrode 76. In addition, the vibration member 20 composed of the resin material 22 and the piezoelectric material 24 arranged in a matrix in the resin material 22 is sandwiched between the electrode 76 and the electrode 78.
Note that the vertical direction here corresponds to the vertical direction in FIG.

  The electrode 72, the electrode 76, and the electrode 78 are made of a material having electrical conductivity, for example, silver or a silver / palladium alloy. Silver is a low-resistance general-purpose material and is advantageous from the viewpoint of manufacturing cost and manufacturing process. Further, the silver / palladium alloy is a low resistance material excellent in oxidation resistance and excellent in reliability. The thickness of the electrode 72, the electrode 76, and the electrode 78 is preferably 1 to 50 μm. When the thickness is less than 1 μm, it becomes difficult to form the film uniformly. On the other hand, when the thickness exceeds 50 μm, the electrode 72, the electrode 76, or the electrode 78 becomes a restraint surface with respect to the piezoelectric vibrator 10 or the vibration member 20, and the energy conversion efficiency is lowered.

  As shown in FIG. 1, the oscillation device 100 includes an elastic member 26. The elastic member 26 is provided on the edge of the vibration member 20. Further, the elastic member 26 is provided, for example, on the entire circumference of the vibration member 20. The elastic member 26 is made of, for example, a resin material such as urethane, PET, or polyethylene. The support member 30 supports the vibration member 20 via the elastic member 26. Thereby, since the edge part of the vibration member 20 becomes a free end, the vibration amplitude of the vibration member 20 can be increased.

  As illustrated in FIG. 1, the oscillation device 100 includes a control unit 90 and a signal generation unit 92. The signal generation unit 92 is connected to the electrode 72, the electrode 76, and the electrode 78, and generates an electrical signal that is input to the piezoelectric vibrator 10 and the vibration member 20. The control unit 90 is connected to the signal generation unit 92 and controls signal generation by the signal generation unit 92. The control unit 90 controls the generation of the signal of the signal generation unit 92 based on information input from the outside, whereby the output of the oscillation device 100 can be controlled.

When the oscillation device 100 is used as a parametric speaker, the control unit 90 inputs a modulation signal as a parametric speaker to the piezoelectric vibrator 10 via the signal generation unit 92. In this case, the piezoelectric vibrator 10 uses a sound wave of 20 kHz or more, for example, 100 kHz, as a signal transport wave.
When the oscillation device 100 is used as a normal speaker, the control unit 90 may input the audio signal as it is to the piezoelectric vibrator 10 via the signal generation unit 92.
When the oscillation device 100 is used as a sound wave sensor, the signal input to the control unit 90 is a command signal for oscillating sound waves. When the oscillation device 100 is used as a sound wave sensor, the signal generation unit 92 causes the piezoelectric vibrator 10 to generate a sound wave having a resonance frequency of the piezoelectric vibrator 10.

  In addition, when the control unit 90 inputs a signal to the piezoelectric vibrator 10 via the signal generation unit 92, the control unit 90 can input a signal to the vibration member 20 via the signal generation unit 92. In this case, the signal input to the vibration member 20 is a signal for expanding and contracting the piezoelectric material 24 in a direction in which the vibration amplitude of the vibration member 20 increases, for example. That is, a signal for causing the vibration member 20 to perform expansion / contraction vibration in the same phase as the expansion / contraction vibration of the piezoelectric vibrator 10 is input. Thus, by driving the vibrating member 20 simultaneously with the piezoelectric vibrator 10, the vibration amplitude of the vibrating member 20 can be increased. Therefore, the sound pressure level of the oscillation device 100 can be improved.

  In addition, when the control unit 90 inputs a signal to the piezoelectric vibrator 10 via the signal generation unit 92, the control unit 90 may not input a signal to the vibration member 20 via the signal generation unit 92. In this case, the vibration member 20 functions as a shim material. Thus, the input of the signal to the vibration member 20 can be adjusted to an arbitrary condition in accordance with the frequency to be generated, power consumption, and the like.

FIG. 3 is a cross-sectional view showing a modification of the oscillation device 100 shown in FIG. As shown in FIG. 3, in the oscillation device 102, the piezoelectric vibrator 10 having the electrodes 72 and 74 on the upper and lower surfaces and the vibration member 20 having the electrodes 76 and 78 on the upper and lower surfaces are formed by the insulating film 80. It may be configured to be insulated from each other.
In this case, the signal generation unit 92 is connected to the electrode 72 and the electrode 74 and generates an electric signal to be input to the piezoelectric vibrator 10. The signal generator 92 is connected to the electrode 76 and the electrode 78 and generates an electric signal to be input to the vibration member 20.

Next, the effect of this embodiment will be described. In the oscillation device 100 according to the present embodiment, the vibration member 20 that restrains the piezoelectric vibrator 10 on one surface partially includes the piezoelectric material 24. For this reason, a sound wave can be output using the driving force by the piezoelectric vibrator 10 and the driving force by the vibration member 20. Therefore, the output of the oscillation device 100 can be increased.
The piezoelectric material 24 is included in the vibration member 20 that functions as a vibration film of the oscillation device 100. For this reason, the above-described effect can be obtained without increasing the thickness of the oscillation device 100.
Thus, according to the present embodiment, it is possible to provide an oscillation device capable of improving the sound pressure level while reducing the size.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

DESCRIPTION OF SYMBOLS 10 Piezoelectric vibrator 20 Vibrating member 22 Resin material 24 Piezoelectric material 26 Elastic member 30 Support member 72, 74, 76, 78 Electrode 80 Insulating film 90 Control part 92 Signal generation part 100 Oscillator 102 Oscillator

Claims (8)

A piezoelectric vibrator;
A vibration member that constrains the piezoelectric vibrator in one surface and partially includes a piezoelectric material;
A support member for supporting an edge of the vibration member;
An oscillation device comprising: The oscillation device according to claim 1,
The vibration member is an oscillation device including a resin material. The oscillation device according to claim 2,
The oscillation device in which the resin material is polyethylene terephthalate, polyethylene, or urethane. The oscillation device according to claim 2 or 3,
The oscillation device is formed by arranging the piezoelectric materials in a matrix in the resin member which is a base material. The oscillation device according to any one of claims 2 to 4,
An oscillation device in which a weight ratio of the piezoelectric material to the resin material is 1/100 or more and 1/3 or less. The oscillation device according to any one of claims 1 to 5,
An oscillation device in which at least a part of the piezoelectric material is positioned so as to overlap the piezoelectric vibrator in a plan view. The oscillation device according to any one of claims 1 to 6,
An elastic member provided at an edge of the vibration member;
The oscillation device in which the support member supports the vibration member via the elastic member.   A portable terminal device on which the oscillation device according to claim 1 is mounted.

Images