Patent US3571632A successfully refreshed from Google Patents.
US3571632A
Expired / Lapsed
US
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Electromechanical filter
Assignee: US Philips Corp
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Filing: 1967-11-30
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Granted: 1971-03-23
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Expires: 1987-11-30
Abstract
Abstract An electromechanical filter comprises a disc or flat annular member of a polarized piezoelectric material, with an electrode on each face. The region of the member between the electrodes has remanent radial polarization. Thus, the polarization and the electric field are perpendicular to each other within the same volume.
Inventors
- 👤 Martijn De Jong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:27
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/54; H03H9/56; H03H9/562
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
68 words
An electromechanical filter, comprising a flat circular piezoelectric member with a volume having opposing surfaces and a residual polarization in a radial direction substantially parallel to said surfaces, and a pair of planar electrodes coupled to said opposing surfaces respectively and at least partially enclosing said polarized volume thereby to produce an electric field perpendicular to the polarization of the volume of said member contained between said electrodes.
Claim 2
Dependent Claim
68 words
An electromechanical filter, comprising a flat circular piezoelectric member with a volume having opposing surfaces and a residual polarization in a radial direction substantially parallel to said surfaces, and a pair of planar electrodes coupled to said opposing surfaces respectively and at least partially enclosing said polarized volume thereby to produce an electric field perpendicular to the polarization of the volume of said member contained between said electrodes.
Claim 3
Dependent Claim
27 words
The filter of claim 1 wherein the internal diameter where the residual radial polarization begins is between 0.3 and 0.5 times the external diameter of said member.
Claim 4
Dependent Claim
24 words
A filter as claimed in claim 1 wherein said electrodes each comprise a circular disc having a central hole concentric with said member disc.
Claim 5
Dependent Claim
28 words
A filter as claimed in claim 3 wherein the diameter of at least one electrode hole is 0.3 to 0.5 times the external diameter of said disc electrode.
Claim 6
Dependent Claim
25 words
A filter as claimed in claim 1 wherein the thickness of said electrodes is chosen to maximize the ratio of the fundamental to overtone energy.
Claim 7
Dependent Claim
26 words
A filter as claimed in claim 1 wherein said member comprises a material selected from the group consisting of barium titanate, barium-strontium titanate, or lead-titanate zirconate.
Claim 8
Dependent Claim
20 words
A filter as claimed in claim 1 further comprising damping material disposed partially about said member to suppress unwanted overtones.
References Cited (Backward Citations)
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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) | 1974-03-22 | 1974-09-21 | 1975-03-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-22 | 1978-09-21 | 1979-03-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-22 | 1982-09-21 | 1983-03-23 | $7700.00 | Window Closed / Lapsed |