JP-7855998-B2 - Electroacoustic converter

Inventors

• 樋口 貴史
• 榎本 哲也
• 情家 智也
• 山田 英雄
• 川合 祐輔
• 臼井 孝英

Assignees

• 株式会社デンソー
• トヨタ自動車株式会社
• 株式会社ミライズテクノロジーズ
• 日清紡マイクロデバイス株式会社

Dates

Publication Date

20260511

Application Date

20221223

Claims (11)

1. Electroacoustic converter (1), A piezoelectric element portion (3) is formed in the shape of a plate having a thickness direction along the directional axis (CA), and comprises a piezoelectric film (31) made of a piezoelectric material, A support portion (2) is provided to fixally support the fixed end portion (34a), which is the outer edge of the piezoelectric element portion in an in-plane direction perpendicular to the directional axis, A stretchable film (4) is laminated with the piezoelectric element portion in the thickness direction of the plate and bonded to the piezoelectric element portion, Equipped with, The piezoelectric element portion is The through hole (35) that penetrates in the thickness direction of the plate, A vibrating section (34) extending in a cantilevered shape in the direction toward the through hole from the fixed end, which is the in-plane direction, Equipped with, The expandable membrane has a diaphragm covering portion (41) that covers at least the free end (34b) on the leading edge side in the extending direction of the vibrating portion, and a through-hole covering portion (42) that covers the through-hole. The through-hole covering portion has a peripheral portion (44) provided at the joint with the inner edge surface (35a), which is a wall surface constituting the inner edge of the through-hole, a thin portion (45) formed to be smaller in the thickness direction than the peripheral portion, and a thick portion (46) formed to be larger in the thickness direction than the thin portion . Electroacoustic converter.
2. The through hole, the expandable membrane, or the thin-walled portion is formed to have a circular or polygonal shape in the in-plane direction. The electroacoustic converter according to claim 1.
3. The aforementioned thickened portion is provided at the stress concentration point in the through-hole covering portion. The electroacoustic converter according to claim 1 .
4. The stretchable membrane is formed such that the Young's modulus is 1/10 or less of that of the vibrating part. The electroacoustic converter according to claim 1.
5. The stretchable membrane is formed from a photosensitive resin material. The electroacoustic converter according to claim 1.
6. The through-hole covering portion is provided over the entire length of the through-hole in the thickness direction of the plate, The electroacoustic converter according to claim 1.
7. The thin-walled portion is provided at one end of the through-hole covering portion in the thickness direction, The electroacoustic converter according to claim 1.
8. The thin-walled portion is provided at the bottom of the thin-walled portion forming hole (43) formed in the expansion membrane so as to open toward the other side in the thickness direction of the sheet, The electroacoustic transducer according to claim 7 .
9. The electroacoustic transducer according to claim 1, wherein the peripheral portion is formed to have a larger dimension in the plate thickness direction than the vibrating portion.
10. The thin-walled portion is formed to have dimensions in the thickness direction smaller than those of the vibrating portion. The electroacoustic converter according to claim 1.
11. The piezoelectric element portion comprises a pair of vibrating portions facing each other across the through-hole, The electroacoustic converter according to claim 1.

Description

This invention relates to an electroacoustic transducer. The piezoelectric element described in Patent Document 1 comprises a piezoelectric element portion, a support portion that supports the peripheral edge of the piezoelectric element portion, and a stretchable membrane with higher stretchability than the piezoelectric element portion. The stretchable membrane is provided in the vibration region inside the peripheral edge of the piezoelectric element portion. A slit is provided in the vibration region of the piezoelectric element portion, penetrating the vibration region in the thickness direction. The stretchable membrane covers at least a portion of the opening of the slit in the vibration region and is arranged to integrate the vibration regions separated by the slit. In this type of piezoelectric element, where a slit is provided in the piezoelectric film to form a cantilever structure, the bending of the piezoelectric film can increase the effective gap between the beams, sometimes leading to a decrease in acoustic resistance. In this regard, according to the configuration described in Patent Document 1, the bending of the vibration region is suppressed by providing an expandable membrane, thereby suppressing the increase in the gap. Furthermore, even if the vibration region does bend, the decrease in acoustic resistance can be suppressed by positioning the expandable membrane to cover at least a portion of the slit. Therefore, this configuration can suppress a decrease in the signal-to-noise ratio and sensitivity characteristics. Moreover, the expandable membrane has higher expandability than the piezoelectric element portion. This suppresses the adverse effect on the resonant frequency due to residual stress in the expandable membrane. Additionally, damage to the expandable membrane due to vibration in the vibration region is suppressed. International Publication No. 2021/024865 This is a side cross-sectional view showing a schematic configuration of an electroacoustic transducer according to the first embodiment of the present invention.Figure 1 is a plan view showing a schematic configuration of the piezoelectric element and the stretchable membrane in the electroacoustic converter according to the first embodiment.Figure 1 is a schematic diagram showing the dimensional relationships of each part of the stretchable membrane in the electroacoustic converter according to the first embodiment.This is a side cross-sectional view showing a schematic configuration of an electroacoustic converter according to a second embodiment of the present invention.Figure 4 is a plan view showing a schematic configuration of the piezoelectric element and the stretchable membrane in the electroacoustic converter according to the second embodiment shown.Figure 4 is a schematic diagram showing the dimensional relationships of each part of the stretchable membrane in the electroacoustic converter according to the second embodiment.Figures 1 and 4 are plan views showing a modified example of the in-plane shape of the through-hole in the piezoelectric element section.This is a plan view showing another modified example of the in-plane shape of the through-hole in the piezoelectric element section shown in Figures 1 and 4.This is a plan view showing yet another modified example of the in-plane shape of the through-hole in the piezoelectric element shown in Figures 1 and 4.This is a plan view showing yet another modified example of the in-plane shape of the through-hole in the piezoelectric element shown in Figures 1 and 4.This is a plan view showing yet another modified example of the in-plane shape of the through-hole in the piezoelectric element shown in Figures 1 and 4.This is a plan view showing yet another modified example of the in-plane shape of the through-hole in the piezoelectric element shown in Figures 1 and 4.This is a plan view showing yet another modified example of the in-plane shape of the through-hole in the piezoelectric element shown in Figures 1 and 4.This is a plan view showing yet another modified example of the in-plane shape of the through-hole in the piezoelectric element shown in Figures 1 and 4.This is a plan view showing yet another modified example of the in-plane shape of the through-hole in the piezoelectric element shown in Figures 1 and 4.This is a plan view showing yet another modified example of the in-plane shape of the through-hole in the piezoelectric element shown in Figures 1 and 4.This is a plan view showing yet another modified example of the in-plane shape of the through-hole in the piezoelectric element shown in Figures 1 and 4.This is a plan view showing yet another modified example of the in-plane shape of the through-hole in the piezoelectric element shown in Figures 1 and 4.Figures 1 and 4 are plan views showing a modified example of the fixing structure of the stretchable membrane in the electroacoustic transducer.Figures 1 and 4 are plan views showing a modified example