TUNABLE SURFACE-WAVE SIGNAL-TRANSLATING DEVICE

• US 3,621,482 A
• Filed: 12/04/1969
• Issued: 11/16/1971
• Est. Priority Date: 12/04/1969
• Status: Expired due to Term

• Current Assignee: Robert Adler
• Original Assignee: Robert Adler
• Inventors: Adler, Robert
• Primary Examiner(s): Herman Karl Saalbach
• Assistant Examiner(s): C. Baraff
• Application Number:
  US04/882,238
• Time in Patent Office: 712 Days
• Field of Search: 333/72,30 250/211,213 315/3 310/8.1,8.2,8.6
• US Class Current: 333/193
• CPC Class Codes: H03H 9/02968 with optical devices mounting in enclosures H03H9/12
• CPC Class Codes: H03H 9/25 Constructional features of resonators using surface acoustic waves devices for manipulating acoustic surface waves in general G10K11/36
• CPC Class Codes: H03H 9/72 Networks using surface acoustic waves

Abstract

A filter has an acoustic-surface-wave propagating medium, a source and/or load for translating signals of different frequencies within a given range and a plurality of pairs of interleaved conductive combs formed on a surface of the medium with each comb pair having a unique intertooth spacing such that the comb pairs individually respond to different assigned frequencies within the range. The structure includes a plurality of conductive ribbons that are laterally spaced successively apart across a portion of the medium and a pair of conductive strips oriented generally transverse to the ribbons is coupled across the source or load. Sandwiched between the strips and ribbons is a layer of photoconductive material. A light source illuminates at least two discrete regions of the photoconductive layer disposed individually on respective different ones of the strips in alignment with respective different ones of the ribbons. In one version, the illuminated regions each overlie respective different groups of ribbons with those different groups together then serving as the teeth of the interleaved combs. In another version, different pairs of the ribbons are coupled across respective different interleaved comb pairs and the illumination of crossing points, as between the strips and different pairs of the ribbons, selectively coupled different ones of the comb pairs to the strips. In both versions, the strips are coupled to the source or load.

Claims

1. An optically controllable solid-state acoustic-surface-wave signal-translating device comprising:

a substrate of piezoelectric material capable of propagating acoustic surface waves;

a selectable transducer arrangement including a plurality of spaced surface electrodes composed of flat conductors on a major surface of said substrate;

a pair of elongated terminal conductors, transparent to a predetermined type of radiation, extending transversely of said surface electrodes;

a layer of photoconductive material, of a type which increases its conductivity in response to exposure to said radiation, interposed between the intersections of said terminal conductoRs with said surface electrodes; and

an optical system for projecting said radiation upon selected ones of said intersections of said terminal conductors and said surface electrodes to establish electrical connections between selected ones of said surface electrodes and said respective terminal conductors to activate any of a plurality of different surface-wave transducer electrode patterns depending upon the particular ones of said surface electrodes which are activated by said electrical connections.

2. A device as defined in claim 1 in which said flat conductors are disposed transversely of the acoustic-wave propagating path in said substrate and are spaced along said path by a distance no greater than one-half acoustic wavelength in said substrate of waves at the highest frequency of a signal to be translated and in which said selected intersections are mutually spaced in the direction of said path by an effective distance equal to one-half acoustic wavelength in said substrate at the frequency of a selected signal.

3. A device as defined in claim 2 in which said terminal conductors are in spaced parallel relation to one another and are disposed generally centrally with respect to the length of said flat conductors and in which said selected intersections alternate between said pair of terminal conductors and are spaced from one another in the direction of said path of acoustic-wave propagation.

4. A device as defined in claim 3 in which said selected portions each overlie a respective plurality of successive ones of said flat conductors.

5. A device as defined in claim 1 in which said transducer arrangement further includes a plurality of pairs of interleaved conductive combs individually disposed on respective different portions of said substrate and in which different pairs of said flat conductors are electrically coupled individually across respective different ones of said pairs of combs.

6. A surface-wave filter for connection to a device for translating signals having frequencies within a given frequency range comprising:

a medium propagative of acoustic surface waves of frequencies within said range;

a plurality of conductive ribbons disposed transversely of a surface of said medium and laterally spaced from one another by a distance no greater than one-half acoustic wavelength in said medium of said waves at the highest frequency of said range;

a layer of photoconductive material overlying the median sections of said ribbons;

a pair of light-transparent-conductive strips, overlying said layer and oriented in spaced relation to one another and generally transverse to said ribbons, for connecting to said signal-translating device; and

a source of light for illuminating at least two discrete regions of said strips mutually spaced in a direction transverse to said ribbons by an effective distance equal to one-half acoustic wavelength in said medium at a selected frequency within said range and individually disposed on respective ones of said strips.

7. A surface-wave filter in accordance with claim 6 in which a plurality of longitudinally spaced discrete regions of each of said strips is illuminated, and in which each illuminated region of each strip is spaced from the closest illuminated regions of the other strip by one-half acoustic wavelength in said medium at said selected frequency.

8. A surface-wave filter for connection to a device for translating signals having frequencies within a given frequency range comprising:

a medium propagative of acoustic surface waves;

a plurality of pairs of interleaved conductive combs disposed on said surface with each pair individually having lead-in conductor portions and further have a unique intertooth spacing to respond to an assigned different frequency in said range;

a pair of light-transparent-conductve strips for connecting to said signal-translating device extending transversely across said lead-in conductor portions of said plurality of combs;

a layer of photoconductive material interposed between the intersections of said light-transparent strips with said lead-in conductor portions of said plurality of combs; and

a source of light for illuminating at least two discrete regions of said material through portions of said strips that are in alignment with said lead-in conductor portions of a selected one of said combs.

9. A surface-wave filter in accordance with claim 8 in which said light source illuminates selected regions of said material to effect a response from only a selected one of said pairs of combs.