US4714848A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrically induced mechanical precompression of ferroelectric plates
Assignee: United States Department of Energy
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Filing: 1987-03-02
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Granted: 1987-12-22
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Expires: 2007-03-02
Abstract
Abstract A method of electrically inducing mechanical precompression of a ferroelectric plate covered with electrodes utilizes the change in strains of the plate as functions of applied electric field. A first field polarizes and laterally shrinks the entire plate. An outer portion of the electrodes are removed, and an opposite field partially depolarizes and expands the central portion of the plate against the shrunk outer portion.
Inventors
- 👤 Peter J. Chen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:28
CPC Classifications
H; H10; H10N; H10N30/00; H10N30/01; H10N30/04; H10N30/045; Y; Y10; Y10T; Y10T29/00; Y10T29/42
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
64 words
A method of mechanically precompressing a ferroelectric plate having opposed surfaces and including an outer portion surrounding a central portion, said method comprising the steps of: electrically polarizing said plate, whereby the plate is axially stretched and laterally shrunk; and electrically partially depolarizing only the central portion of said plate, whereby the central portion is laterally expanded against the outer portion of said plate.
Claim 2
Independent Claim
64 words
A method of mechanically precompressing a ferroelectric plate having opposed surfaces and including an outer portion surrounding a central portion, said method comprising the steps of: electrically polarizing said plate, whereby the plate is axially stretched and laterally shrunk; and electrically partially depolarizing only the central portion of said plate, whereby the central portion is laterally expanded against the outer portion of said plate.
Claim 3
Dependent Claim
38 words
The method of claim 1 wherein said step of electrically polarizing said plate comprises: covering each surface of said plate with an electrically conductive electrode; and applying a first dc voltage across said electrodes to polarize said plate.
Claim 4
Dependent Claim
58 words
The method of claim 2 wherein said step of applying a first dc voltage comprises: slowly increasing the dc voltage from 0 volts to a first predetermined value; holding the dc voltage at the first predetermined value for a sufficient period of time to cause polarization of said material; and slowly reducing the dc voltage to 0 volts.
Claim 5
Dependent Claim
48 words
The method of claim 1 wherein said step of electrically partially depolarizing only the central portion of said plate comprises: applying a second dc voltage across electrodes covering only the central portion of said plate, the second dc voltage being of opposite polarity from the first dc voltage.
Claim 6
Dependent Claim
57 words
The method of claim 2 wherein said step of electrically partially depolarizing only the central portion of said plate comprises: removing only the portion of each electrode covering the outer portion of said plate; and applying a second dc voltage across the remaining electrodes, the second dc voltage being of opposite polarity from the first dc voltage.
Claim 7
Dependent Claim
58 words
The method of claim 4 wherein said step of applying a second dc voltage comprises: slowly increasing the dc voltage from 0 volts to a second predetermined value; holding the dc voltage at the second predetermined value for a sufficient period of time to cause partial depolarization of said material; and reducing the dc voltage to 0 volts.
Claim 8
Dependent Claim
47 words
The method of claim 1 wherein said central portion comprises a middle portion surrounding an inner portion, and further comprising the steps of: further partially depolarizing only the inner portion of said plate, whereby the inner portion is laterally expanded against the middle portion of said plate.
Claim 9
Dependent Claim
33 words
The method of claim 1 wherein said ferroelectric plate is a disk, and the intersection of said outer and central portions is defined by a cylinder concentric about the axis of said disk.
Claim 10
Dependent Claim
33 words
The method of claim 7 wherein said ferroelectric plate is a disk, and the intersections between said outer, middle, and inner portions are defined by cylinders concentric about the axis of said disk.
Claim 11
Independent Claim
155 words
A method of mechanically precompressing a ferroelectric plate having opposed surfaces and including an outer portion surrounding a middle portion surrounding an inner portion, said method comprising the steps of: covering each surface of said plate with an electrode; applying a first dc voltage across said electrodes to electrically polarize said plate, whereby the plate is axially stretched and laterally shrunk; applying a second dc voltage across electrodes covering only the middle and inner portions of said plate, the second dc voltage being of opposite polarity from the first dc voltage, whereby said middle and inner portions are laterally expanded against the outer portion of said plate; and applying a third dc voltage across electrodes covering only the inner portion of said plate, the third dc voltage being of the same polarity and of greater magnitude than the second dc voltage, whereby said inner portion is laterally expanded against the middle portion of said plate.
Claim 12
Independent Claim
155 words
A method of mechanically precompressing a ferroelectric plate having opposed surfaces and including an outer portion surrounding a middle portion surrounding an inner portion, said method comprising the steps of: covering each surface of said plate with an electrode; applying a first dc voltage across said electrodes to electrically polarize said plate, whereby the plate is axially stretched and laterally shrunk; applying a second dc voltage across electrodes covering only the middle and inner portions of said plate, the second dc voltage being of opposite polarity from the first dc voltage, whereby said middle and inner portions are laterally expanded against the outer portion of said plate; and applying a third dc voltage across electrodes covering only the inner portion of said plate, the third dc voltage being of the same polarity and of greater magnitude than the second dc voltage, whereby said inner portion is laterally expanded against the middle portion of said plate.
Claim 13
Dependent Claim
33 words
The method of claim 10 wherein said ferroelectric plate is a disk, and the intersections between said outer, middle, and inner portions are defined by cylinders concentric about the axis of said disk.
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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) | 1990-12-21 | 1991-06-22 | 1991-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-21 | 1995-06-22 | 1995-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-21 | 1999-06-22 | 1999-12-22 | $7700.00 | Window Closed / Lapsed |