Optical tracking system for positioning a beam of light

• US 5,491,680 A
• Filed: 10/07/1994
• Issued: 02/13/1996
• Est. Priority Date: 06/06/1990
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Pauli, Giles A.
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): HUBER, PAUL W
• Application Number:
  US08/320,014
• Time in Patent Office: 494 Days
• Field of Search: 369/44.23, 369/44.17, 369/44.14, 369/112, 369/124, 369/120, 369/117, 369/121, 369/94, 359/95, 359/198, 359/199, 359/214, 359/221, 359/224, 359/855
• US Class Current: 369/112.29
• CPC Class Codes: G11B 7/08564 using galvanomirrors
• CPC Class Codes: G11B 7/0901 for track following only G11B7/0925, G11B7/094, G11B7/0941, G11B7/0943, G11B7/0945, G11B7/0946, G11B7/0948 take precedence

Abstract

An optical tracking and positioning system is provided which comprises a beam source 14 which generates a beam which is transmitted through a splitter/filter 16. The beam issues from splitter/filter 16 and is selectively deflected to areas of an optical storage medium 12 by a mirror 18 which is controlled by a mirror control system 20. The beam is transmitted from mirror 18 through correction optics 22 and reflects off the surface of the optical storage medium 12. The beam returns along a coincident path and is separated by splitter/filter 16 and directed to a detector 24 which reads the data stored in optical storage medium 12. According to a preferred embodiment of the present invention, the mirror 18 comprises a deformable mirror device 26.

Claims

1. A method of accessing data positions on an optical storage medium comprising the steps of:

generating a beam of light from a light source;

rotating a mirror about an axis freed a predetermined distance from the light source in the path of the beam of light a predetermined distance from the light source to direct the beam of light to a selected portion of the optical storage medium, wherein the mirror comprises;

a torsion rod fixed with respect to a semiconductor substrate, thereby forming the axis;

a torsion beam pivotally connected to the torsion rod; and

an electrode connected to the semiconductor substrate to provide an electrostatic force to the torsion beam;

controlling the rotation of the mirror with an electrical mirror control system, wherein the mirror is directly responsive to the electrostatic force that is resultant from electrical control signals from the electrical mirror control system;

detecting the beam reflected from the optical storage medium; and

reading data stored in the selected portion of the optical storage medium responsive to said detection of the reflected beam.

2. An optical tracking system for positioning a beam of light on an optical storage medium, comprising:

a light source operable to generate the beam;

a mirror rotatable about an axis fixed a predetermined distance from said light source and operable to selectively deflect the beam toward a plurality of selected positions on the surface of the optical storage medium, the optical storage medium operable to reflect the beam to generate a reflected beam, wherein the mirror comprises;

a torsion rod fixed with respect to a semiconductor substrate, thereby forming the axis;

a torsion beam pivotally connected to the torsion rod; and

an electrode connected to the semiconductor substrate to provide an electrostatic force to the torsion beam;

an electrical mirror control system coupled to said mirror and operable to control the rotation of said mirror, wherein the mirror is directly responsive to the electrostatic force that is resultant from electrical control signals from the electrical mirror control system such that the beam may be directed toward an plurality of selectable positions on the surface of the optical storage medium to access said plurality of positions;

a detector disposed in the path of the reflected beam operable to read data stored by the optical medium responsive to the reflected beam, the reflected beam and the impinging beam having substantially coincident paths; and

a beam splitter disposed in the coincident paths and operable to direct the reflected beam to said detector.

3. The system of claim 2 wherein said optical storage medium comprises a plurality of tracks, each track comprising a plurality of data storage positions, and wherein said mirror control system and said deformable mirror device are operable to select any of said plurality of tracks and wherein the system further comprises:

an optical storage medium movement system operable to move said optical storage medium such that data positions within a selected track may be sequentially accessed by the beam.

4. The optical tracking storage system of claim 2 wherein the electrical control signal received by the mirror device are analog control signals.

5. The optical tracking storage system of claim 2 wherein the mirror device responds to the electrical control signal in a linear fashion.

6. An optical tracking storage system for positioning a beam of light on an optical storage medium, comprising:

a light source operable to generate the beam;

a mirror rotatable about an axis fixed a predetermined distance from said light source and operable to selectively deflect the beam toward a plurality of selected portions of the optical storage medium, wherein the mirror comprises;

a torsion rod fixed with respect to a semiconductor substrate, thereby forming the axis;

a torsion beam pivotally connected to the torsion rod; and

an electrode connected to the semiconductor substrate to provide an electrostatic force to the torsion beam; and

an electrical mirror control system connected to the mirror;

wherein the mirror is directly responsive to the electrostatic force theft is resultant from an electrical control signal from the electrical mirror control system such that the beam may be directed toward a plurality of selectable portions of an optical storage medium to access a plurality of data storage positions resident in said selected portions and wherein the beam comprises an impinging beam and where the impinging beam is reflected by the surface of the optical medium to create a reflected beam and further comprising;

a detector disposed in the path of the reflected beam operable to read data stored by the optical medium responsive to the reflected beam.

7. The system of claim 6 wherein the reflected beam and the impinging beam have a substantially coincident path and further comprising:

a beam splitter disposed in the coincident path and operable to direct the reflected beam to said detector.