# US 8,770,724 B2 · Piezoelectric element, liquid ejecting head, and liquid ejecting apparatus

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- Number: US 8,770,724 B2
- Document ID: US8770724B2
- Status: Granted
- Kind: B2
- Application number: 13/420,288
- Filed: 2012-03-14
- Published: 2012-09-20
- Granted: 2014-07-08
- Earliest claimed: 2011-03-15
- Assignees: Seiko Epson Corporation
- Applicants: Masao Nakayama; Noboru Furuya
- Inventors: Masao Nakayama; Noboru Furuya
- Web page: https://patentgrep.com/patent/US8770724B2

## CPC

- B41J 2/1612: {of stacked structure type, deformed by compression/extension and disposed on a diaphragm}
- B41J 2/14274: {of stacked structure type, deformed by compression/extension and disposed on a diaphragm}
- B41J 2/1628: {dry etching}
- B41J 2/1629: {wet etching}
- B41J 2/1631: {photolithography}
- B41J 2/1642: {thin film formation by CVD [chemical vapor deposition]}
- B41J 2/1643: {thin film formation by plating}
- B41J 2/1646: {thin film formation by sputtering}
- H10N 30/082: by etching, e.g. lithography
- H10N 30/2047: {Membrane type}
- H10N 30/704: {based on piezoelectric or electrostrictive films or coatings}
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A piezoelectric element including: a first electrode, a piezoelectric layer formed above the first electrode to have a longitudinal direction and a transverse direction, and a second electrode formed above the piezoelectric layer, wherein at least a part of a side surface of the piezoelectric layer in the transverse direction is a concavo-convex surface, and a width of the piezoelectric layer in the transverse direction from the second electrode to the first electrode changes with the concavo-convex surface.

## Claims

### Claim 1

A piezoelectric element comprising:
a first electrode;
a piezoelectric layer formed above the first electrode to have a longitudinal direction and a transverse direction in a planar view, the piezoelectric layer having a side surface following the longitudinal direction; and
a second electrode formed above the piezoelectric layer,
wherein at least a part of the side surface of the piezoelectric layer includes a concavo-convex surface having a plurality of concavities and convexities in a cross-sectional view normal to the longitudinal direction, and
a width of the piezoelectric layer in the transverse direction increases from the second electrode to the first electrode over the extent of the side surface,
wherein the side surface of the piezoelectric layer has a flat surface connected to an upper surface of the piezoelectric layer,
the concavo-convex surface is connected to the flat surface,
the side surface of the flat surface and the second electrode is covered by a first coating layer,
the concavo-convex surface is covered by a second coating layer, and
Young's modulus of the second coating layer is smaller than Young's modulus of the first coating layer and Young's modulus of the piezoelectric layer.

### Claim 2 (depends on 1)

The piezoelectric element according to claim 1, wherein the piezoelectric layer and the first electrode intersect with each other, and the side surface of the piezoelectric layer is a flat surface at another part where the piezoelectric layer intersects with the first electrode.

### Claim 3 (depends on 1)

The piezoelectric element according to claim 1, wherein a width of the second electrode in the transverse direction is smaller than a minimum width of the piezoelectric layer in the transverse direction.

### Claim 4 (depends on 1)

The piezoelectric element according to claim 1, wherein a side surface of the second electrode in the transverse direction is connected to the side surface of the piezoelectric layer in the cross-sectional view.

### Claim 5 (depends on 1)

The piezoelectric element according to claim 1, wherein the side surface of the piezoelectric layer is covered by a coating layer, and Young's modulus of the coating layer is smaller than Young's modulus of the piezoelectric layer.

### Claim 6 (depends on 1)

The piezoelectric element according to claim 1, wherein a material of the first coating layer is aluminum oxide and a material of the second coating layer is a polyimide.

### Claim 7 (depends on 1)

A liquid ejecting head comprising the piezoelectric element according to claim 1.

### Claim 8 (depends on 7)

A liquid ejecting apparatus comprising the liquid ejecting head according to claim 7.