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US4513262A
Expired / Lapsed
US
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Acoustic surface wave device
Assignee: US Philips Corp
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Filing: 1983-09-13
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Granted: 1985-04-23
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Expires: 2003-09-13
Abstract
Abstract An acoustic surface wave device using an interdigital electrode array 2, 3 to launch and receive surface waves overcomes problems of diffraction by making the arrays approximately 3λ c wide between the outer boundaries of the bus bars. As a result, the arrays can each only propagate and transduce a single acoustic surface waveguide mode which is symmetrical about the axis of the array.
Inventors
- 👤 John Schofield
- 👤 Robert F. Milsom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:54
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/02; H03H9/02535; H03H9/02818; H03H9/02881; H03H9/125; H03H9/145; H03H9/14544; H03H9/14573; H03H9/02992; H03H9/14552
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
182 words
An acoustic surface wave device comprising a piezoelectric substrate for propagating acoustic surface waves at a surface thereof and an acoustic surface wave transducer formed on said surface to launch or to receive acoustic surface waves at said surface along a propagation direction parallel to the axis of the transducer, in which said transducer includes at least one interdigital array of two overlapping sets of electrodes with each set connected to one of a pair of opposite bus bars, characterized in that the overall width of an interdigital array between the outer boundaries of a said pair of bus bars measured in a direction at right angles to the acoustic surface wave propagation direction is so determined, in relation to the wavelength λ c at the center frequency f c of the acoustic surface wave pass-band of the transducer, and in relation to the electrode distribution, that a said interdigital array functions as an acoustic surface waveguide which will only propagate and transduce a single acoustic surface wave guided energy mode which is symmetrical about the central propagation axis of the array.
Claim 2
Dependent Claim
182 words
An acoustic surface wave device comprising a piezoelectric substrate for propagating acoustic surface waves at a surface thereof and an acoustic surface wave transducer formed on said surface to launch or to receive acoustic surface waves at said surface along a propagation direction parallel to the axis of the transducer, in which said transducer includes at least one interdigital array of two overlapping sets of electrodes with each set connected to one of a pair of opposite bus bars, characterized in that the overall width of an interdigital array between the outer boundaries of a said pair of bus bars measured in a direction at right angles to the acoustic surface wave propagation direction is so determined, in relation to the wavelength λ c at the center frequency f c of the acoustic surface wave pass-band of the transducer, and in relation to the electrode distribution, that a said interdigital array functions as an acoustic surface waveguide which will only propagate and transduce a single acoustic surface wave guided energy mode which is symmetrical about the central propagation axis of the array.
Claim 3
Dependent Claim
42 words
A device as claimed in claim 1, wherein the substrate comprises Y-cut Z-propagating or 124° to 131° rotated Y-cut X-propagating lithium niobate, characterized in that said overall width of an interdigital array lies in the range 3λ c to 3.5λ c .
Claim 4
Dependent Claim
50 words
A device as claimed in claim 1, wherein the substrate comprises Y-cut Z-propagating or 124° to 131° rotated Y-cut X-propagating lithium niobate, characterized in that said interdigital array is symmetrical about the central propagation axis thereof, and said overall width of the array is not greater than 5λ c .
Claim 5
Dependent Claim
37 words
A device as claimed in claim 1, characterized in that the piezoelectric substrate comprises an anisotropic crystal oriented so that said propagation direction does not lie along a self-collimating direction for the propagation of acoustic surface waves.
Claim 6
Dependent Claim
18 words
A device as claimed in claim 1, characterized in that a said interdigital array comprises an apodized array.
Claim 7
Dependent Claim
35 words
A device as claimed in claim 2 wherein the piezoelectric substrate comprises an anisotropic crystal oriented so that said propagation direction does not lie along a self-collimating direction for the propagation of acoustic surface waves.
Claim 8
Dependent Claim
35 words
A device as claimed in claim 3 wherein the piezoelectric substrate comprises an anisotropic crystal oriented so that said propagation direction does not lie along a self-collimating direction for the propagation of acoustic surface waves.
References Cited (Backward Citations)
US4409571A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-04-22 | 1988-10-22 | 1989-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-22 | 1992-10-22 | 1993-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-22 | 1996-10-22 | 1997-04-23 | $7700.00 | Window Closed / Lapsed |