Piezoelectric element, stator for oscillatory wave motor, oscillatory wave motor, driving control system, optical apparatus, and method for making stator for oscillatory wave motor

Patent metadata

Field	Value
Publication number	US-9893269-B2
Application number	US-201314655036-A
Country	US
Kind code	B2
Filing date	Dec 19, 2013
Priority date	Dec 26, 2012
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

The present invention provides a piezoelectric element that includes a piezoelectric material having first and second surfaces; a common electrode disposed on the first surface; and a plurality of drive phase electrodes, a detection phase electrode, and a non-drive phase electrode disposed on the second surface, the piezoelectric material being sandwiched between the common electrode and the electrodes on the second surface. An absolute value d( 1 ) of a piezoelectric constant of the piezoelectric material ( 1 ) in portions sandwiched between the drive phase electrodes and the common electrode, an absolute value d( 2 ) of a piezoelectric constant of the piezoelectric material ( 2 ) in a portion sandwiched between the detection phase electrode and the common electrode, and an absolute value d( 3 ) of the piezoelectric material ( 3 ) in a portion sandwiched between the non-drive phase electrode and the common electrode satisfy d( 2 )<0.95d( 1 ), d( 3 )<0.95d( 1 ), and 0.9≦d( 3 )/d( 2 )≦1.1.

First claim

The invention claimed is:

1. A piezoelectric element comprising:
a single piece of a piezoelectric material having a first surface and a second surface;
a common electrode disposed on the first surface;
a plurality of drive phase electrodes disposed on the second surface;
a detection phase electrode disposed on the second surface; and
a non-drive phase electrode disposed on the second surface,
wherein an absolute value d( 1 ) of a piezoelectric constant of the piezoelectric material ( 1 ) in portions sandwiched between the plurality of drive phase electrodes and the common electrode, an absolute value d( 2 ) of a piezoelectric constant of the piezoelectric material ( 2 ) in a portion sandwiched between the detection phase electrode and the common electrode, and an absolute value d( 3 ) of a piezoelectric constant of the piezoelectric material ( 3 ) in a portion sandwiched between the non-drive phase electrode and the common electrode satisfy relationships d( 2 )<0.95d( 1 ), d( 3 )<0.95d( 1 ), and 0.9≦d( 3 )/d( 2 )≦1.1.

2. The piezoelectric element according to claim 1 , wherein the absolute value d( 2 ) of the piezoelectric constant of the piezoelectric material ( 2 ) is 0.7 times the absolute value d( 1 ) of the piezoelectric constant of the piezoelectric material ( 1 ) or less.

3. The piezoelectric element according to claim 1 , wherein the piezoelectric material contains less than 1000 ppm of lead.

4. The piezoelectric element according to claim 1 , wherein the piezoelectric material is a piezoelectric ceramic material containing barium titanate as a main component.

5. The piezoelectric element according to claim 1 , wherein the piezoelectric material contains as a main component a perovskite-type metal oxide represented by general formula (1) below:
(Ba 1−x Ca x )(Ti 1−y Zr y Sn z )O 3 (0.02≦x≦0.30, 0.020≦y≦0.095, 0.095, 0≦z≦0.04, and y≦x)   General formula (1).

6. The piezoelectric element according to claim 5 , wherein the perovskite-type metal oxide contains Mn and a Mn content relative to 100 parts by weight of the perovskite-type metal oxide is 0.02 parts by weight or more and 0.40 parts by weight or less on a metal basis.

7. A stator for an oscillatory wave motor, comprising:
the piezoelectric element according to claim 1 , the piezoelectric element having a first surface and a second surface;
a diaphragm disposed on the first surface; and
a power input/output wire disposed on the second surface.

8. An oscillatory wave motor comprising the stator for an oscillatory wave motor according to claim 7 .

9. A driving control system comprising the oscillatory wave motor according to claim 8 .

10. An optical apparatus comprising the driving control system according to claim 9 .

11. A method for producing the stator for an oscillatory wave motor according to claim 7 , the method comprising:
(A) forming a common electrode on a first surface of a piezoelectric material, forming polarizing electrodes on a second surface of the piezoelectric material so as to sandwich the piezoelectric material between the common electrode and the polarizing electrodes, and then applying a voltage to the piezoelectric material so as to polarize the piezoelectric material and obtain a piezoelectric element; and
(B) selecting which of the polarizing electrodes are to be a detection phase electrode and a non-drive phase electrode and connecting a power input/output wire to a part of a surface of the detection phase electrode and a part of a surface of the non-drive phase electrode at a temperature equal to or higher than a depolarization temperature Td of the piezoelectric material.

12. A method for producing the stator for an oscillatory wave motor according to claim 7 , the method comprising:
(A) forming a common electrode on a first surface of a piezoelectric material, forming polarizing electrodes on a second surface of the piezoelectric material so as to sandwich the piezoelectric material between the common electrode and the polarizing electrodes, and then applying a voltage to the piezoelectric material so as to polarize the piezoelectric material and obtain a piezoelectric element;
(B) selecting which of the polarizing electrodes are to be a detection phase electrode and a non-drive phase electrode and connecting a power input/output wire to a part or all parts of a surface of the detection phase electrode and a part or all parts of a surface of the non-drive phase electrode at a temperature equal to or higher than a depolarization temperature Td of the piezoelectric material; and
(C) re-polarizing the piezoelectric material in portions sandwiched between the detection phase electrode and the common electrode and between the non-drive phase electrode and the common electrode.

13. The method according to claim 12 , wherein, the re-polarizing (C) is conducted by applying voltages of the same polarity to the detection phase electrode and the non-drive phase electrode so that the portions sandwiched between the detection phase electrode and the common electrode and between the non-drive phase electrode and the common electrode exhibit the same polarity of expansion and contraction.

14. The method according to 11 , wherein the depolarization temperature Td is 100° C. or higher and 200° C. or lower.

Assignees

• Canon Kk

Inventors

• Ifuku Toshihiro
• Furuta Tatsuo
• Saito Hiroshi
• Kubota Makoto
• Fujita Satoshi

Classifications

• H01L41/047

  Electricity · mapped topic

• H02N2/14

  Drive circuits; Control arrangements {or methods} · CPC title

• Y10T29/43

  Electric condenser making · CPC title

• H01L41/1871

  Electricity · mapped topic

• H02N2/163 Primary

  Motors with ring stator · CPC title