Piezoelectric/electrostrictive film device

• US 20030234595A1
• Filed: 06/17/2003
• Published: 12/25/2003
• Est. Priority Date: 06/21/2002
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Bessho, Yuki, Takahashi, Nobuo
• Granted Patent: US 7,019,438 B2
• Time in Patent Office: Days
• US Class Current: 310/324
• CPC Class Codes: B41J 2/14233 of film type, deformed by bending and disposed on a diaphragm
• CPC Class Codes: H10N 30/2047 Membrane type
• CPC Class Codes: H10N 30/2048 having non-planar shape

Abstract

There is provided a piezoelectric/electrostrictive film device having larger resonant frequency while having flexural displacement that is equal to or superior to that of conventional piezoelectric/electrostrictive film device, and being excellent in rapid response. The piezoelectric/electrostrictive film device comprises a substrate comprising ceramics, and a piezoelectric/electrostrictive actuator including a lower electrode, a piezoelectric/electrostrictive layer and an upper electrode that are sequentially layered on the substrate, the piezoelectric/electrostrictive layer covering an upper surface of the lower electrode and a lower surface of the upper electrode and protruding over edges thereof, wherein the protruded portion of the piezoelectric/electrostrictive layer is coupled to the substrate via a coupling member. The present device shows substantially the same flexural displacement, but a larger resonant frequency of 3% or more, when compared with those of a piezoelectric/electrostrictive film device comprising same materials and same configuration as the present device, but without coupling member.

Claims

1. A piezoelectric/electrostrictive film device comprising a substrate comprising ceramics, and a piezoelectric/electrostrictive actuator including a laminate formed by layering at least one lower electrode, at least one piezoelectric/electrostrictive layer sequentially layered on said substrate, said at least one piezoelectric/electrostrictive layer covering an upper surface of said at least one lower electrode and a lower surface of said at least one upper electrode and protruding over edges thereof,

characterized in that said protruded portion of said piezoelectric/electrostrictive layer is coupled to said substrate via a coupling member, and flexural displacement of said present device is substantially same as, and resonant frequency of the present device is 3% or more larger than, that of a piezoelectric/electrostrictlve film device comprising same materials and same configuration as the present device but including no coupling member.

2. A piezoelectric/electrostrictive film device according to claim 1, wherein penetration depth of Microvickers hardness indenter of said coupling member is larger than that of the piezoelectric/electrostrictive layer and lower than 1.3 μ

m, when measured by using a micro hardness tester and a Diamond Vickers indenter having a diagonal angle of 136 degree at a load of 1 gf and a penetration speed of 0.145 gf/sec.

3. A piezoelectric/electrostrictive film device according to claim 1, wherein the coupling member of the piezoelectric/electrostrictive film device has Young'"'"'s modulus exceeding 2.4 GPa, but lower than that of the piezoelectric/electrostrictive layer.

4. A piezoelectric/electrostrictive film device according to claim 1, wherein said protruded portion of said piezoelectric/electrostrictive layer is coupled to said substrate via a coupling member, and wherein said coupling member comprises an organic-inorganic hybridized material.

5. A piezoelectric/electrostrictive film device according to claim 2, wherein said protruded portion of said piezoelectric/electrostrictive layer is coupled to said substrate via a coupling member, and wherein said coupling member comprises an organic-inorganic hybridized material.

6. A piezoelectric/electrostrictive film device according to claim 4, wherein the entire said protruded portion of said piezoelectric/electrostrictive layer is covered by said coupling member.

7. The piezoelectric/electrostrictive film device according to claim 1, wherein said coupling member contains a coloring agent.

8. The piezoelectric/electrostrictive film device according to claim 6, wherein said coloring agent is a fluorescent pigment.

9. The piezoelectric/electrostrictive film device according to claim 8, wherein said fluorescent pigment is an organic substance being removable by subjecting it to a thermal processing at temperature at which said organic substance is decomposed, or more.

10. A piezoelectric/electrostrictive film device according to claim 1, wherein the piezoelectric/electrostrictive actuator includes a laminate layer being formed by layering alternately on the substrate a predetermined number of lower electrodes, a predetermined number of piezoelectric/electrostrictive layers, and a predetermined number of the upper electrodes in order.

11. A piezoelectric/electrostrictive film device according to claim 2, wherein the piezoelectric/electrostrictive actuator includes a laminate layer being formed by layering alternately on the substrate a predetermined number of lower electrodes, a predetermined number of piezoelectric/electrostrictive layers, and a predetermined number of the upper electrodes in order.

12. A piezoelectric/electrostrictive film device according to claim 1, wherein a plurality of piezoelectric/electrostrictive actuators is provided on the substrate, and at least adjacent two piezoelectric/electrostrictive actuators are coupled with at least one coupling member.

13. A piezoelectric/electrostrictive film device according to claim 2, wherein a plurality of piezoelectric/electrostrictive actuators is provided on the substrate, and at least adjacent two piezoelectric/electrostrictive actuators are coupled with at least one coupling member.

14. A piezoelectric/electrostrictive film device according to claim 1, wherein a plurality of piezoelectric/electrostrictive actuators is provided at a predetermined interval on the substrate, and said at least one coupling member includes a portion formed on upper surface of the substrate between said at least adjacent two piezoelectric/electrostrictive actuators.

15. A piezoelectric/electrostrictive film device according to claim 2, wherein a plurality of piezoelectric/electrostrictive actuators is provided at a predetermined interval on the substrate, and said at least one coupling member includes a portion formed on upper surface of the substrate between said at least adjacent two piezoelectric/electrostrictive actuators.