CN-122003094-A - Piezoelectric device and ultrasonic device

Abstract

The invention provides a piezoelectric device and an ultrasonic device, wherein the deformation of a vibrating plate is large. The piezoelectric device includes a substrate having a vibration region and a non-vibration region surrounding the vibration region, a first electrode disposed so as to span the vibration region and the non-vibration region, a second electrode disposed in the vibration region so as to be separated from the first electrode, a piezoelectric body disposed so as to span the substrate, the first electrode, and the second electrode, and a third electrode disposed on the piezoelectric body so as to overlap at least the first electrode and the second electrode in the vibration region when viewed in a thickness direction of the substrate.

Inventors

• Kochiki
• TAKABE MOTOKI

Assignees

• 精工爱普生株式会社

Dates

Publication Date

20260508

Application Date

20251104

Priority Date

20241106

Claims (9)

1. 1. A piezoelectric device is provided with: A substrate having a vibration region and a non-vibration region surrounding the vibration region; A first electrode disposed across the vibration region and the non-vibration region; a second electrode disposed in the vibration region and separated from the first electrode; a piezoelectric body disposed across the substrate, the first electrode, and the second electrode, and And a third electrode provided on the piezoelectric body, the third electrode overlapping at least the first electrode and the second electrode in the vibration region when viewed in a thickness direction of the substrate.
2. 2. The piezoelectric device of claim 1, wherein, The width of the portion of the first electrode disposed in the vibration region is equal to or less than the width of the second electrode, and the sum of the width of the first electrode disposed in the vibration region and the width of the second electrode is smaller than the width of the vibration region, as viewed in the thickness direction.
3. 3. The piezoelectric device of claim 2, wherein, The first electrode is disposed so as to sandwich the second electrode.
4. 4. The piezoelectric device according to claim 3, wherein, When the sum of the widths of the portions of the first electrode disposed in the vibration region is set to W1, the width of the second electrode is set to W2, and the width of the vibration region is set to Wc, the following are satisfied: , 。
5. 5. the piezoelectric device of claim 1, wherein, The piezoelectric device includes a voltage applying section that applies a voltage between the first electrode and the third electrode and between the second electrode and the third electrode, The voltage applying section makes a phase of a voltage applied between the first electrode and the third electrode different from a phase of a voltage applied between the second electrode and the third electrode.
6. 6. The piezoelectric device of claim 5, wherein, In the case where a phase difference between a phase of a voltage applied between the first electrode and the third electrode and a phase of a voltage applied between the second electrode and the third electrode is ΔΦ, it is satisfied that: 。
7. 7. The piezoelectric device of claim 1, wherein, The piezoelectric device is provided with: A support substrate disposed opposite to the third electrode on the opposite side of the substrate, and And a support leg portion that bonds at least any one of the substrate, the piezoelectric body, and the third electrode to the support substrate in the non-vibration region.
8. 8. The piezoelectric device of claim 7, wherein, The support substrate has a through hole at a portion overlapping the vibration region as viewed in the thickness direction.
9. 9. An ultrasonic device comprising the piezoelectric device according to any one of claims 1 to 8, The ultrasonic device drives the piezoelectric device to transmit ultrasonic waves.

Description

Piezoelectric device and ultrasonic device Technical Field The present invention relates to a piezoelectric device and an ultrasonic device. Background Conventionally, a piezoelectric device is known in which a piezoelectric element is arranged on a vibration plate, and the piezoelectric element is applied with a voltage to vibrate the vibration plate (for example, refer to patent document 1). The piezoelectric device of patent document 1 is an ultrasonic device, and includes a silicon substrate having a void, a vibration plate provided on the silicon substrate so as to cover the void, a first electrode disposed on the vibration plate, a piezoelectric body provided at a position overlapping the void when viewed in a thickness direction, and a second electrode provided on the piezoelectric body. In the ultrasonic device, when the width of the gap is Cw and the width of the piezoelectric body is Pw, the following is adoptedThe piezoelectric body is arranged in the mode of (a). Patent document 1 Japanese patent application laid-open No. 2021-153293 However, in the conventional piezoelectric device as in patent document 1, there is a problem that the diaphragm is deflected toward the void portion by applying a voltage to the piezoelectric body, but the diaphragm is not deflected toward the opposite side to the void portion, so that the deformation amount of the diaphragm is small. Therefore, in the case of using the piezoelectric device as the ultrasonic device, since the deformation amount of the vibration plate is small, the sound pressure of the output ultrasonic wave also becomes small. Disclosure of Invention The piezoelectric device according to a first aspect of the present disclosure includes a substrate having a vibration region and a non-vibration region surrounding the vibration region, a first electrode disposed so as to span the vibration region and the non-vibration region, a second electrode disposed in the vibration region so as to be separated from the first electrode, a piezoelectric body disposed so as to span the substrate, the first electrode, and the second electrode, and a third electrode disposed on the piezoelectric body so as to overlap at least the first electrode and the second electrode in the vibration region when viewed from a thickness direction of the substrate. An ultrasonic device according to a second aspect of the present disclosure includes the piezoelectric device according to the first aspect, and transmits ultrasonic waves by driving the piezoelectric device. Drawings Fig. 1 is a cross-sectional view showing a schematic structure of an ultrasonic device of a first embodiment. Fig. 2 is a plan view showing a schematic structure of the ultrasonic device according to the first embodiment. Fig. 3 is a diagram showing displacement of the vibration region when the ultrasonic device of the first embodiment is driven. Fig. 4 is a diagram showing the driving efficiency in the case where (w1+w2)/Wc is changed in the first embodiment. Fig. 5 is a diagram showing the driving efficiency in the case where W1/W2 is changed in the first embodiment. Fig. 6 is a diagram showing the driving efficiency in the case where the phase difference between the first driving voltage and the second driving voltage is changed in the first embodiment. Fig. 7 is a cross-sectional view showing a schematic structure of an ultrasonic device of the second embodiment. Fig. 8 is a schematic diagram showing a schematic structure of a head of the third embodiment. Fig. 9 is a plan view showing a schematic structure of the piezoelectric device of modification 2. Description of the reference numerals 10. 10A ultrasonic device, 10B and 10C piezoelectric device, 11 substrate, 11A vibration region, 11B non-vibration region, 12 first electrode, 13 second electrode, 14 piezoelectric body, 15 third electrode, 16 vibration suppressing portion, 17 supporting substrate, 20 voltage controlling portion, 21 first power source, 22 second power source, 23 common potential portion, 171 supporting leg portion and 172 through hole. Detailed Description First embodiment A first embodiment of the present disclosure will be described. Fig. 1 is a cross-sectional view showing an outline structure of an ultrasonic device which is a piezoelectric device according to the present embodiment, and fig. 2 is a plan view showing an outline structure of the ultrasonic device. As shown in fig. 1, the ultrasonic device 10 includes a substrate 11, a first electrode 12, a second electrode 13, a piezoelectric body 14, a third electrode 15, a vibration suppressing portion 16, and a voltage control portion 20. In fig. 2, the piezoelectric body 14 and the third electrode 15 are not shown. In the present embodiment, the first electrode 12 and the second electrode 13 are stacked on the substrate 11, and the piezoelectric body 14 is stacked so as to cover the substrate 11, the first electrode 12, and the second electrode 13, and the third electrode 15 i