US4492940A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic surface-wave bandpass filter
Assignee: Hitachi Ltd
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Filing: 1983-02-04
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Granted: 1985-01-08
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Expires: 2003-02-04
Abstract
Abstract An acoustic surface-wave bandpass filter includes a substrate made of a piezoelectric material. Acoustic surface waves travelling on a substrate surface provided with electrically conductive narrow stripes, slits or grooves undergo interference, wherein acoustic surface waves excited at frequency in VHF and UHF range are taken out as electric signals. The number of interleaved fingers constituting input transducers and output transducers of the filter is selected greater for the transducer located at the center than those disposed at both end portions. Leakage of acoustic surface-wave energy from the end transducers can be remarkably reduced, while the number of the transducers constituting the filter can be decreased. Significant reduction of loss of the filter is thus attained.
Inventors
- 👤 Mitsutaka Hikita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:18
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/64; H03H9/6423; H03H9/6426; H03H9/02; H03H9/125; H03H9/145; H03H9/14544; H03H9/1455
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
93 words
An acoustic surface-wave bandpass filter comprising a plurality of input transducers and a plurality of output transducers formed on a substrate and arrayed in the direction in which acoustic surface waves travel on said substrate, each of said input and output transducers having a plurality of interleaved metal electrodes, wherein the number of said interleaved metal electrodes of at least one of said input and output transducers is increased for the transducer located at the center portion of said array as compared with the transducers located at both end portions of said array.
Claim 2
Dependent Claim
93 words
An acoustic surface-wave bandpass filter comprising a plurality of input transducers and a plurality of output transducers formed on a substrate and arrayed in the direction in which acoustic surface waves travel on said substrate, each of said input and output transducers having a plurality of interleaved metal electrodes, wherein the number of said interleaved metal electrodes of at least one of said input and output transducers is increased for the transducer located at the center portion of said array as compared with the transducers located at both end portions of said array.
Claim 3
Dependent Claim
20 words
An acoustic surface-wave bandpass filter according to claim 1, further including reflectors provided at both ends of said filter, respectively.
Claim 4
Dependent Claim
28 words
An acoustic surface-wave bandpass filter according to claim 1, further including a plurality of intermediate transducers for interconnecting said input transducers and said output transducers in serial-parallel connection.
Claim 5
Dependent Claim
40 words
An acoustic surface-wave bandpass filter according to claim 3, wherein the number of interleaved fingers of the intermediate transducers located at the center portion is determined to be greater than those of the intermediate transducers located at both end portions.
Claim 6
Dependent Claim
92 words
An acoustic surface-wave bandpass filter comprising a plurality of input transducers and a plurality of output transducers formed on a substrate and arrayed in the direction in which acoustic surface waves travel on said substrate, each of said input and output transducers having a plurality of interleaved metal electrodes, wherein the number of the electrodes of at least one of said transducers is determined such that it takes a maximum value at the center portion of the filter and monotonically decreases in the directions away from said center portion of the filter.
Claim 7
Dependent Claim
92 words
An acoustic surface-wave bandpass filter comprising a plurality of input transducers and a plurality of output transducers formed on a substrate and arrayed in the direction in which acoustic surface waves travel on said substrate, each of said input and output transducers having a plurality of interleaved metal electrodes, wherein the number of the electrodes of at least one of said transducers is determined such that it takes a maximum value at the center portion of the filter and monotonically decreases in the directions away from said center portion of the filter.
References Cited (Backward Citations)
US3582840A
Cited
US4143343A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-08 | 1988-07-09 | 1989-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-08 | 1992-07-09 | 1993-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-08 | 1996-07-09 | 1997-01-08 | $7700.00 | Window Closed / Lapsed |