Optical reading or writing apparatus

• US 4,881,204 A
• Filed: 04/22/1988
• Issued: 11/14/1989
• Est. Priority Date: 04/28/1987
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Okada, Kazuo, Imai, Hitoshi, Tadokoro, Michihiro
• Primary Examiner(s): Psitos, Aristotelis M.
• Application Number:
  US07/185,052
• Time in Patent Office: 571 Days
• Field of Search: 369/46, 369/44, 369/258, 369/261, 369/292
• US Class Current: 369/44.39
• CPC Class Codes: G11B 17/34 Guiding record carriers during transducing operation, e.g. for track following G11B17/32 takes precedence
• CPC Class Codes: G11B 23/507 combined with means for reducing influence of physical parameters, e.g. temperature change, moisture
• CPC Class Codes: G11B 7/0037 with discs
• CPC Class Codes: G11B 7/0956 to compensate for tilt, skew, warp or inclination of the disc, i.e. maintain the optical axis at right angles to the disc

Abstract

An information-carrying medium having the form of a disc is rotated around a central axis. The temperature of the disc is controlled by a temperature-adjusting element facing the surface of the disc.

Claims

1. An optical reading or writing apparatus comprising

an information-carrying medium on which information can be read or written optically, the information-carrying medium having the form of a disc rotating around a central axis and receiving a light beam from an optical head that is driven in the radial direction of the disc,

a detection means located near the information-carrying medium, for detecting the angle between the optic axis of the light beam and the surface of the information-carrying medium,

a temperature-adjusting element located near and facing the surface of the information-carrying medium, for creating a temperature difference between the two surfaces of the information-carrying medium and thereby causing a thermal deformation that bends the information-carrying medium in a desired direction, and

a control circuit for receiving a signal from the detection means and controlling the temperature-adjusting element by supplying energy to it in such a way as to maintain a perpendicular relationship between the surface of the information-carrying medium and the optic axis.

2. An optical reading or writing apparatus as set forth in claim 1,

wherein the temperature-adjusting element is located facing the information-carrying medium near its circumference.

3. An optical reading or writing apparatus as set forth in claim 1,

wherein the detection means is located at the circumference of the information-carrying medium.

4. An optical reading or writing apparatus as set forth in claim 1,

wherein the temperature-adjusting element comprises a plurality of elements which are disposed at different radial positions to create a temperature difference along the radial direction on a surface of the information-carrying medium.

5. An optical reading or writing apparatus as set forth in claim 4,

wherein the detection means comprises an inner means and an outer means which are positioned in radially inner and outer regions of the information-carrying medium, respectively.

6. An optical reading or writing apparatus as set forth in claim 1,

wherein the temperature-adjusting element comprises a heating element and a cooling element disposed on opposite sides of the information-carrying medium.

7. An optical reading or writing apparatus as set forth in claim 1,

wherein the temperature-adjusting element is a semiconductor element employing the Peltier effect.

8. An optical reading or writing apparatus as set forth in claim 1,

wherein the temperature-adjusting element is also used to remove condensed moisture.

9. An optical reading or writing apparatus as set forth in claim 1,

wherein the detection means is driven in the radial direction to detect said angle at different positions along the radial direction.