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KR-102962904-B1 - Piezoelectric element for piezoelectric speaker

KR102962904B1KR 102962904 B1KR102962904 B1KR 102962904B1KR-102962904-B1

Abstract

The present invention relates to a piezoelectric element for a piezoelectric speaker for improving sound pressure characteristics, comprising: a dummy piezoelectric layer; a plurality of upper piezoelectric layers stacked on top of the dummy piezoelectric layer; and a plurality of lower piezoelectric layers stacked on the bottom of the dummy piezoelectric layer; and a plurality of electrode layers provided between each of the plurality of piezoelectric layers, wherein a voltage is applied to the adjacent piezoelectric layers, excluding the dummy piezoelectric layer, to form different electric field directions when driven, and adjacent piezoelectric layers are polarized in different directions, and the number of the plurality of upper piezoelectric layers and the number of the plurality of lower piezoelectric layers are provided differently.

Inventors

  • 이덕규
  • 박기태
  • 박준식

Assignees

  • (주)동일기연
  • (주)아이언디바이스
  • 한국전자기술연구원

Dates

Publication Date
20260512
Application Date
20221230

Claims (10)

  1. In a piezoelectric element for a piezoelectric speaker, A plurality of piezoelectric layers comprising a plurality of lower piezoelectric layers, a lower dummy piezoelectric layer stacked on top of the plurality of lower piezoelectric layers, a plurality of intermediate piezoelectric layers stacked on top of the lower dummy piezoelectric layer, an upper dummy piezoelectric layer stacked on top of the plurality of intermediate piezoelectric layers, and a plurality of upper piezoelectric layers stacked on top of the upper dummy piezoelectric layer; and It includes a plurality of electrode layers provided between each of the plurality of piezoelectric layers, wherein power is applied to the piezoelectric layers adjacent to each other, excluding the upper dummy piezoelectric layer and the lower dummy piezoelectric layer, to form different electric field directions when driven. A piezoelectric element for a piezoelectric speaker characterized by adjacent piezoelectric layers being polarized in different directions.
  2. In paragraph 1, A piezoelectric element for a piezoelectric speaker characterized in that the thicknesses of the upper dummy piezoelectric layer and the lower dummy piezoelectric layer are different from each other.
  3. In paragraph 1, The number of the upper piezoelectric layers is different from the number of the intermediate piezoelectric layers, and A piezoelectric element for a piezoelectric speaker characterized in that the number of lower piezoelectric layers is different from the number of intermediate piezoelectric layers.
  4. In paragraph 1, A piezoelectric element for a piezoelectric speaker characterized in that the number of upper piezoelectric layers, the number of middle piezoelectric layers, and the number of lower piezoelectric layers are different from each other.
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Description

Piezoelectric element for piezoelectric speaker The present invention relates to a piezoelectric element, and more specifically, to a piezoelectric element for a piezoelectric speaker with improved sound pressure characteristics. A piezoelectric element refers to a device capable of converting electrical and mechanical energy into one another. When pressure is applied to a piezoelectric element, voltage is generated; conversely, when voltage is applied, changes in internal pressure cause an increase or decrease in volume or length. Since piezoelectric speakers utilizing piezoelectric elements are easy to miniaturize, they are being applied to mobile phones, tablets, and various terminals. The piezoelectric element provided in the piezoelectric speaker is composed of a plurality of piezoelectric layers and electrodes, and the piezoelectric element contracts/expands according to the voltage applied through the electrodes, and the diaphragm to which the piezoelectric element is attached vibrates, thereby enabling sound output. Recently, numerous technologies have been introduced to improve the sound pressure characteristics of piezoelectric speakers. Korean Patent Publication No. 2011-0064369 presents a piezoelectric speaker in which the piezoelectric element and the diaphragm are attached in a tilted structure that is horizontally offset, thereby minimizing sound distortion by preventing standing waves generated by structural symmetry. However, the aforementioned patent merely alters the arrangement of the piezoelectric element within the speaker and does not represent a technology that improves the sound pressure characteristics of the piezoelectric element itself. FIG. 1 is a cross-sectional view for explaining a piezoelectric element for a piezoelectric speaker according to a first embodiment of the present invention. Figure 2 is a drawing for explaining the electrode layer illustrated in Figure 1. Figure 3 is a diagram illustrating the connection relationship of the electrode layers during polarization and driving of the piezoelectric element. Figure 4 is a diagram for explaining the driving method of the piezoelectric element shown in Figure 1. FIGS. 5A and 5B are drawings for explaining the sound pressure characteristics of a piezoelectric speaker to which the piezoelectric element of the present invention is applied. FIG. 6 is a cross-sectional view illustrating a piezoelectric element for a piezoelectric speaker according to a second embodiment of the present invention. Embodiments of the present invention will be described in detail below with reference to the attached drawings. FIG. 1 is a cross-sectional view for explaining a piezoelectric element for a piezoelectric speaker according to a first embodiment of the present invention. Referring to FIG. 1, the piezoelectric element (10) includes a plurality of piezoelectric layers (100) and an electrode (200) provided between the plurality of piezoelectric layers (100). The piezoelectric element (10) is composed of a plurality of piezoelectric layers (100) and an electrode layer (200) provided on top thereof, and the pressure changes according to the voltage applied to the piezoelectric layer through the electrode, and accordingly, a diaphragm (not shown) to which the piezoelectric element is attached vibrates. The piezoelectric layer (100) includes an upper piezoelectric layer (110), a dummy piezoelectric layer (120), and a lower piezoelectric layer (130). A single piezoelectric layer (120) is provided, a plurality of upper piezoelectric layers (110) are provided on the upper part of the piezoelectric layer (120), and a plurality of lower piezoelectric layers (130) are provided on the lower part of the piezoelectric layer (120). The upper piezoelectric layer (110) and the lower piezoelectric layer (130) are distinguished based on whether they are located above or below the dummy piezoelectric layer (120), and the dummy piezoelectric layer (120), the upper piezoelectric layer (110), and the lower piezoelectric layer (130) can all be made of the same material. Meanwhile, the number of upper piezoelectric layers (110) and lower piezoelectric layers (130) in FIG. 1 is merely an example and may be provided differently. The piezoelectric element (10) undergoes a polarization process during manufacturing, so that adjacent piezoelectric layers (100) are polarized in different thickness directions. The arrows shown in FIG. 1 indicate the polarization directions. For example, when the dummy piezoelectric layer (120) is polarized in the first direction among the thickness directions of the piezoelectric side, the first upper piezoelectric layer (110a) located immediately above the dummy piezoelectric layer (120) is polarized in the second direction opposite to the first direction, and the second upper piezoelectric layer (110b) located above the first upper piezoelectric layer (110a) is polarized in the first direction. Then, the third upper piezoelectric layer