US4649313A
Expired / Lapsed
US
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Piezoelectric displacement element
Assignee: Murata Manufacturing Co Ltd
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Filing: 1984-09-19
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Granted: 1987-03-10
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Expires: 2004-09-19
Abstract
Abstract Disclosed herein is a piezoelectric displacement element utilizing a sintered body obtained by stacking three or more ceramic layers (5a to 5h) through internal electrodes (6b to 6h) and co-firing the same. The sintered body has first, second and third regions when viewed in the direction of thickness. The first and third regions are so formed as to be displaced in reverse directions to each other. The second region consists of a plurality of piezoelectric ceramic layers (5d, 5e) in such a manner that an internal electrode (6e) interposed between the piezoelectric ceramic layers (5d, 5e) is connected with neither potentials in a driven state, whereby the second region is adapted not to be positively driven, to function as a buffer area.
Inventors
- 👤 Toshio Ogawa
- 👤 Satoru Fujishima
- 👤 Akira Ando
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:58
CPC Classifications
H; H10; H10N; H10N30/00; H10N30/20; H10N30/204; H10N30/50
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
221 words
A monolithic piezoelectric displacement element comprising: a sintered body including ceramic material comprised in at least three ceramic layers and internal electrodes interposed between said ceramic layers, said sintered body being formed by stacking said at least three ceramic layers with a respective group of at least one said internal electrode being located between each adjacent pair of ceramic layers and then simultaneously firing the ceramic layers and electrodes together, said ceramic layers being coextensive with one another and having coextensive longitudinal edges, said internal electrodes extending to and alongside the major portion of said longitudinal edges: said sintered body having first, second and third regions when viewed in a thickness direction of said displacement element; said ceramic material in said first and third regions being conditioned to be displaced in reverse directions to each other when appropriate electrical potentials are applied to internal electrodes of said first and third regions; and buffer means, comprising said ceramic material in said second region which is located between said first and third regions and which is characterized in that displacement of said second region is significantly smaller than displacement of said first and third regions, said buffer means being instrumental for alleviating a stress concentration in said second region in a manner that reduces a displacement hysteresis associated with said piezolectric displacement element.
Claim 2
Dependent Claim
221 words
A monolithic piezoelectric displacement element comprising: a sintered body including ceramic material comprised in at least three ceramic layers and internal electrodes interposed between said ceramic layers, said sintered body being formed by stacking said at least three ceramic layers with a respective group of at least one said internal electrode being located between each adjacent pair of ceramic layers and then simultaneously firing the ceramic layers and electrodes together, said ceramic layers being coextensive with one another and having coextensive longitudinal edges, said internal electrodes extending to and alongside the major portion of said longitudinal edges: said sintered body having first, second and third regions when viewed in a thickness direction of said displacement element; said ceramic material in said first and third regions being conditioned to be displaced in reverse directions to each other when appropriate electrical potentials are applied to internal electrodes of said first and third regions; and buffer means, comprising said ceramic material in said second region which is located between said first and third regions and which is characterized in that displacement of said second region is significantly smaller than displacement of said first and third regions, said buffer means being instrumental for alleviating a stress concentration in said second region in a manner that reduces a displacement hysteresis associated with said piezolectric displacement element.
Claim 3
Dependent Claim
39 words
A piezoelectric displacement element in accordance with claim 1, wherein said buffer means comprises means for equalizing the potential of electrodes provided on opposite sides of said second region as measured in the thickness direction of said sintered body.
Claim 4
Dependent Claim
31 words
A piezoelectric displacement element in accordance with claim 1, wherein said buffer means comprises a region of weaker polarization than that of respective ceramic layers in said first and third regions.
Claim 5
Dependent Claim
47 words
A piezoelectric displacement element in accordance with claim 3, wherein said second region includes first and second ceramic layers, and said buffer means further includes a mesh-patterned internal electrode interposed between said first and second ceramic layers, said mesh-patterned internal electrode being one of said internal electrodes.
Claim 6
Dependent Claim
50 words
A piezoelectric displacement element in accordance with claim 3, wherein said second region includes a plurality of ceramic layers, and said buffer means is implemented by forming each said ceramic layer of said second region larger in thickness than each of said ceramic layers forming said first and third regions.
Claim 7
Dependent Claim
23 words
A piezoelectric displacement element in accordance with claim 1, wherein said second region is non-polarized and said first and third regions are polarized.
Claim 8
Dependent Claim
50 words
A piezoelectric displacement element in accordance with claim 1, wherein said second region includes first and second ceramic layers, and said buffer means comprises a said internal electrode which is interposed between said first and second ceramic layers of said second region and which is in an electrical open state.
Claim 9
Dependent Claim
35 words
A piezolectric displacement element in accordance with claim 1, wherein the number of said ceramic layers making up said first region is different than the number of said ceramic layers making up said second region.
Claim 10
Dependent Claim
29 words
A piezoelectric displacement element in accordance with claim 1, wherein said first and second regions are adjacent one another and said second and third regions are adjacent one another.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-03-09 | 1990-09-08 | 1991-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-09 | 1994-09-08 | 1995-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-09 | 1998-09-08 | 1999-03-10 | $7700.00 | Window Closed / Lapsed |