Piezoelectric actuator

一种压电致动器、压电体的技术，应用在压电/电致伸缩换能器、传感器、电气元件等方向，能够解决大电阻、外壳异常声音、音圈燃烧等问题，达到缓和碰撞、高可靠性的效果

Inactive Publication Date: 2006-08-02
NEC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, electromagnetic actuators have a problem in that it is difficult to reduce power consumption since a large amount of current flows in the voice coil to generate magnetic force
However, such shielding may require large space
Also for this reason, electromagnetic actuators are not suitable for use in small devices such as cellular phones
Also, there is the problem that if the voice coil is made of thinner wire and has a high resistance, the voice coil may burn due to the large amount of current used to drive it (which is characteristic of electromagnetic audio components)
[0006] Incidentally, since piezoelectric ceramics have high stiffness, piezoelectric actuators have a problem in that they can only vibrate at a small average amplitude compared to electromagnetic actuators
Disadvantages of leakage of such vibrations that may cause abnormal sound generated by the housing

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1-9

[0086] For evaluating the effect of the present invention, evaluate the present invention according to the following examples 1-9 and comparative examples 1-4

[0087] Invention of properties of piezoelectric actuators. The evaluation items are as follows.

[0088] (Evaluation 1) Measurement of resonance frequency: The resonance frequency was measured when an AC voltage of 1 V was applied.

[0089] (Evaluation 2) Maximum amplitude of vibration velocity: When an AC voltage of 1 V was applied, the maximum amplitude of vibration velocity at the resonance frequency was measured.

[0090] (Evaluation 3) The average amplitude of the vibration velocity: eg Figure 10 As shown, the amplitudes of the vibration velocities were measured at 20 measurement points (indicated by 1-20 in the figure) equally spaced along the longitudinal direction of the piezoelectric element 1, and their average values ​​were calculated.

[0091] (Evaluation 4) Vibration mode: such as Figure 11A and 11B...

example 1

[0096] make Figure 12A , 12B The piezoelectric actuator shown. Figure 12A A top plan view showing the base, beam members, and support members. The unit of each value in the figure is millimeter. Figure 12B The exploded simultaneous views of the piezoelectric element are shown in sequence. The piezoelectric actuator of Example 1 has a piezoelectric element 101a, a base 121a, a support member 104a, and a beam member 122a. The piezoelectric member 101a is bonded to the base 121a using epoxy-based glue, and the base 121a is connected to the support member 104a by four beam members 122a.

[0097] Such as Figure 12B As shown, the piezoelectric element 101a is a single-layer piezoelectric element composed of an upper insulating layer 133a, an upper electrode layer 131a, a piezoelectric body 103a, a lower electrode layer 132a, and a lower insulating layer 133a'. The upper insulating layer 133 a and the lower insulating layer 133 a ′ have a length of 10 mm, a width of 10 mm, ...

example 2

[0106] In Example 2, the number of beam members attached to the base was changed from four in Example 1 to two in order to confirm the degree of reduction in resonance frequency. Such as Figure 14 As shown, the conditions are the same as in Example 1 except for the number of beam members. The piezoelectric actuator is circular with a diameter of 16 mm and a thickness of 0.45 mm. The unit of each value in the figure is millimeter. The piezoelectric actuator gives a reciprocating vibration mode, the resonance frequency is 498HZ, the maximum amplitude of the vibration velocity is 172mm / s, and the maximum vibration velocity ratio is 0.86.

[0107] It was confirmed from a comparison between Example 1 and Example 2 that by changing the number of beam members, the resonance frequency can be lowered without causing a large change in vibration mode or vibration velocity amplitude.

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PUM

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Abstract

A piezo-electric actuator is provided which is capable of providing large vibration amplitude, is adjustable for resonance frequency, and has high reliability while avoiding an increase in outer dimensions. A piezo-electric actuator comprising: piezo-electric element la having piezo-electric body 3 a which is provided with at least two opposing surfaces, wherein the surfaces perform an expanding and contracting motion in accordance with the state of an electric field; a constraint member 21 a for constraining piezo-electric element 1 a on at least one of the two surfaces, a supporting member disposed around constraint member 21 a, and a plurality of beam members 22 a each having both ends fixed to constraint member 21 a and supporting member 4 a, respectively, wherein each beam member has a neutral axis for bending in a direction substantially parallel with the constrained surface, wherein the constraint member vibrates by vibration which is generated by the constraining effect between the constraint member and the piezo-electric element, and is amplified by the beam members.

Description

technical field [0001] The present invention relates to a small piezoelectric actuator used in electronic equipment. Background technique [0002] Electromagnetic actuators are commonly used as drive components for acoustic components such as speakers due to their ease of handling. The electromagnetic actuator includes a permanent magnet, a voice coil, and a diaphragm, and vibrates a low-rigidity diaphragm made of an organic film and fixed to the voice coil by the operation of a magnetic circuit in a stator using the magnet. Therefore, they exhibit a reciprocating vibration mode and can provide large vibration amplitudes. [0003] Incidentally, in recent years, as demand for cellular phones and personal computers has increased, demand for power-saving actuators has been increasing. However, the electromagnetic actuator has a problem in that it is difficult to reduce power consumption since a large amount of current flows in the voice coil to generate magnetic force. In ad...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04R17/00
CPCH04R17/00
Inventor 大西康晴佐佐木康弘土岐望
Owner NEC CORP
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