Surface acoustic wave pickup and recording device

• US 4,281,407 A
• Filed: 12/14/1979
• Issued: 07/28/1981
• Est. Priority Date: 12/14/1979
• Status: Expired due to Term

• Current Assignee: RCA Corporation
• Original Assignee: RCA Corporation
• Inventors: Tosima, Soitiro
• Primary Examiner(s): Moffitt, James W.
• Assistant Examiner(s): MCELHENY JR, DONALD E
• Application Number:
  US06/103,444
• Time in Patent Office: 592 Days
• Field of Search: 179/100.4 C, 179/100.41 P, 179/100.41 J, 179/100.41 R, 179/100.1 G, 310/313, 310/334, 310/335
• US Class Current: 369/130
• CPC Class Codes: G10K 11/36 Devices for manipulating acoustic surface waves electro-acoustic amplifiers H03F13/00; networks comprising electro-acoustic elements H03H9/00
• CPC Class Codes: G11B 11/16 using recording by mechanical cutting, deforming or pressing G11B11/002 takes precedence
• CPC Class Codes: G11B 9/00 Recording or reproducing using a method not covered by one of the main groups G11B3/00 - G11B7/00; Record carriers therefor G11B11/00 takes precedence driving or moving of heads G11B21/02

Abstract

A surface acoustic wave (SAW) pickup and record stylus is constructed from an elongated substrate which supports the propagation of SAW. The substrate is tapered to a tip at one end and a fan-shaped interdigital electrode structure having curved fingers is formed thereon. During operation in the pickup mode a beam of SAW is focused to the tip of the stylus which is arranged in contact with a record medium. During playback, the beam reflected by the record medium generates a signal in the interdigital electrode of the stylus representative of the acoustic conditions at the stylus tip and, correspondingly, of the information recorded on the record medium surface. In the record mode the stylus is brought into contact with a record medium. During recording, the input power applied to the interdigital electrode is increased to effect a deformation of the surface of the record medium representative of the information to be recorded.

Claims

1. In a disc record or playback system for recording or retrieving information in the form of surface variations in a disc-shaped record medium, a surface acoustic wave stylus, comprising:

an elongated member tapered to a tip at one end, said member being arranged to support the propagation of surface acoustic wave in at least one region of said member; and

electrode means provided in the vicinity of said tip for focusing surface acoustic waves to said tip.

2. The surface acoustic wave stylus according to claim 1 wherein said focussing electrode means comprises a fan-shaped interdigital electrode.

3. The surface acoustic wave stylus according to claim 2 wherein said fan-shaped interdigital electrode comprises curved fingers.

4. The surface acoustic wave stylus according to claim 3 wherein said fan-shaped electrode is positioned on said member such that the narrowest section of said fan-shaped electrode is in the vicinity of the narrowest portion of said tapered end of said member.

5. The surface acoustic wave stylus according to claim 4 wherein said member is formed from a piezoelectric material.

6. The surface acoustic wave stylus according to claim 4 further comprising:

a piezoelectric film overlying said fan-shaped interdigital electrode.

7. A surface acoustic wave device, comprising:

an elongated member tapered to a tip at one end, said member being arranged to support the propagation of surface acoustic waves in at least one region of said member;

electrode means provided in the vicinity of said tip for focusing surface acoustic waves to said tip, said electrode means comprising a fan-shaped interdigital electrode having curved fingers;

said fan-shaped electrode being positioned on said member such that the narrowest section of said fan-shaped electrode is in the vicinity of the narrowest portion of said tapered end of said member;

means, coupled to said interdigital electrode, for generating surface acoustic waves on the surface of said member in said at least one region; and

means, coupled to said interdigital electrode, for detecting impedance variations of said interdigital electrode;

whereby said surface acoustic wave device is used to recover information signals recorded on a surface of a record medium and whereby the impedance variations detected by said interdigital electrode are representative of the information signals recorded on said record medium surface.

8. A surface acoustic wave device, comprising:

an elongated member tapered to a tip at one end, said member being arranged to support the propagation of surface acoustic waves in at least one region of said member;

electrode means provided in the vicinity of said tip for focusing surface acoustic waves to said tip, said electrode means comprising a fan-shaped interdigital electrode having curved fingers;

said fan-shaped electrode being positioned on said member such that the narrowest section of said fan-shaped electrode is in the vicinity of the narrowest portion of said tapered end of said member;

said member having a shank end opposite said tapered end; and

a reflecting interdigital electrode interposed between said fan-shaped interdigital electrode and said shank end of said member.

9. In a recording system for recording information signals on a record medium, the apparatus comprising:

a surface acoustic wave stylus having a tapered tip on one end thereof, said tapered tip having a fan-shaped interdigital electrode structure formed thereon;

said surface acoustic wave device being supported such that said tapered tip contacts said record medium;

means for establishing relative motion between said tapered tip and said record medium; and

means for coupling said information signals to be recorded to said interdigital electrode structure whereby said tapered tip effects variations in said record medium corresponding to said information signals.

10. In a playback system for recovering information signals recorded in the form of variations in a record medium, the apparatus comprising:

a surface acoustic wave stylus having a tapered tip on one end thereof, said tapered tip having a fan-shaped interdigital electrode structure formed thereon;

said surface acoustic wave device being supported such that said tapered tip contacts said record medium;

means for establishing relative motion between said tapered tip and said record medium; and

means, coupled to said interdigital electrode structure, for sensing signals which vary in accordance with variations on said record medium corresponding to said information signals.