US3764928A
Expired / Lapsed
US
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Methods and devices for amplifying elastic waves
Assignee: Thales SA
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Filing: 1972-09-08
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Granted: 1973-10-09
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Expires: 1992-09-08
Abstract
Abstract Method and device for amplifying elastic waves by the interaction of these waves with a charge carrier wave of lower speed. The method consists in placing in the path of the charge carrier wave facilities for generating periodic disturbances, so as to render periodic the interaction between charge carrier wave and elastic wave, thereby giving rise to space harmonics. By using a space harmonic corresponding to a carrier wave with a speed lower than that of the elastic wave, the value of the electric field needed to propel the charge carriers is considerably reduced.
Inventors
- 👤 P Tournois
- 👤 F Gires
- 👤 C Maerfeld
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:41
CPC Classifications
H; H03; H03F; H03F13/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
92 words
Method of amplifying elastic waves by interaction with a charge carrier wave generated by a propelling electric field, wherein said interaction is made periodically discontinuous by arranging in the path of the carrier waves generators of local periodic electrical disturbances, thereby creating space harmonics of desired degree (p) and the same frequency (f), the given amplitude, with an electric field of reduced value, being produced by utilising the action of a space harmonic corresponding to a charge carrier wave whose speed (vd) is less than the speed (vc) of the elastic wave.
Claim 2
Dependent Claim
92 words
Method of amplifying elastic waves by interaction with a charge carrier wave generated by a propelling electric field, wherein said interaction is made periodically discontinuous by arranging in the path of the carrier waves generators of local periodic electrical disturbances, thereby creating space harmonics of desired degree (p) and the same frequency (f), the given amplitude, with an electric field of reduced value, being produced by utilising the action of a space harmonic corresponding to a charge carrier wave whose speed (vd) is less than the speed (vc) of the elastic wave.
Claim 3
Dependent Claim
146 words
Device for amplifying elastic waves to put into effect the method according to claim 1, comprising a solid compressible medium for propagating elastic waves supplied by a source, which is provided with input and output transducers, a part of the propagation path being subjected to a charge carrier propelling electric field supplied by a continuous voltage source of adjustable value, wherein there are, between the electrodes (4) applying said field and parallel to the wave surface of the charge carrier wave, conductive elements (6) which generate periodic electrical disturbances, are spaced at regular intervals (a) and cross the path of said waves, the presence of said elements causing periodic interaction between carrier wave and elastic wave which given rise to space harmonics with a desired speed of propagation (vd), the existence of which permits a given amplification for a reduced voltage applied to said electrodes (4).
Claim 4
Dependent Claim
96 words
Device for amplification according to claim 2, wherein (FIG. 1) a material is used which is both piezoelectric and semiconductive and said conductive elements (6) are made up of a network of conducting bands distributed over the solid medium (1) at a constant rate (a), the value of which is the nearest to half the length ( lambda c/2) of the sound wave, the thickness of said band being very slight in comparison with said wave length ( lambda c) and its width being chosen to eliminate the influence of unused space harmonics of degree (p).
Claim 5
Dependent Claim
37 words
Device according to claim 3, wherein the selected degree of harmonic is p 1, the constant unit is a lambda c/2, the width of band b a/2 lambda c/4 and its thickness is less than lambda c/10.
Claim 6
Dependent Claim
133 words
Device according to claim 2, wherein (FIG. 2) the piezoelectric and semiconductor underlayer (1) includes a conducting guide line (7), in which the propagation speed is less than that of the underlayer and which links the input and output transducers (2, 3) by periodically crossing the charge carrier wave path bounded by said electrodes (4), arranged on the underlayer, in such a way as to meet in phase sound wave and charge carrier wave at every point of intersection (6) of their paths, the width (e) of the charge carrier flux being small in relation to the wavelength ( lambda c) of the sound wave in order to reduce the phase variation of this wave at said points of intersection which constitute the place where tHe disturbance generating the periodic interaction is created.
Claim 7
Dependent Claim
50 words
Device according to claim 5, wherein said conducting line (7) is made up of a gold band laid on the underlayer (1), the contour of the band being in the form of a line with periodic bands of a period 2a and the intersections being spaced by the rate a.
Claim 8
Dependent Claim
61 words
Device according to claim 2, wherein (FIG. 3) there is a piezoelectric material and a semiconductor material (1,8), one being laid in a thin layer on the other and provided with said electrodes (4), said periodic disturbances (6) being made up of a network of conducting strips which are spaced at equal intervals (a) and arranged on said thin layer (8).
Claim 9
Dependent Claim
33 words
Device according to claim 7, wherein said strips are of metal, aluminium or gold, executed on said thin layer (8) by a photo-engraving process, the transducers (2, 3) being of the interdigital type.
Claim 10
Dependent Claim
83 words
Device according to claim 2, wherein (FIG. 4) there is a piezoelectric underlayer (1) and an insulating underlayer (9) provided with a thin semiconductor layer (8) which is equipped with said electrodes (4) and separated by a layer of air (10) of a thickness within 500 and 1,000 A, said disturbances being created by parallel conducting bands (6) laid at equal intervals on the surface of said thin layer on the inside of said air layer whose crucial thickness depends on said bands.
References Cited (Backward Citations)
US3717819A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |