Optical disc and optical system for reproducing the optical disc

• US 5,436,885 A
• Filed: 03/08/1994
• Issued: 07/25/1995
• Est. Priority Date: 03/12/1993
• Status: Expired due to Term

• Current Assignee: Pioneer Electronic Corporation (Pioneer Corporation)
• Original Assignee: Pioneer Electronic Corporation (Pioneer Corporation)
• Inventors: Okumura, Yoichi, Iida, Tetsuya, Taniguchi, Hitoshi
• Primary Examiner(s): Popek, Joseph A.
• Assistant Examiner(s): Nguyen, Tan
• Application Number:
  US08/207,201
• Time in Patent Office: 504 Days
• Field of Search: 369/275.1, 369/275.2, 369/275.3, 369/44.37, 369/285, 369/286, 369/283, 369/275.5, 369/44.38, 369/284, 428/64, 428/65
• US Class Current: 369/275.2
• CPC Class Codes: G11B 7/00455 involving reflectivity, absorption or colour changes
• CPC Class Codes: G11B 7/005 Reproducing G11B7/0065 takes precedence
• CPC Class Codes: G11B 7/24 Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the arrangement of information on the carrier G11B7/007
• CPC Class Codes: G11B 7/2572 consisting essentially of organic materials

Abstract

An optical disc has a recording film with information recorded thereon, and a photochromic material film provided adjacent the recording film. The photochromic material film is made of a photochromic material. The photochromic material has a first state irradiated with reading light having a first wavelength. In the first state, the transmittance of the material is increased so as to enable reading of the recorded information. The photochromic material further has a second state irradiated with auxiliary light having a second wavelength, where the transmittance becomes low so as to disable the reading of the recorded information.

Claims

1. An optical disc having a recording film disposed at a light receiving side and having information recorded thereon comprising:

a photochromic material film provided on the recording film at an information recorded side;

a reflection film disposed on the photochromic material film; and

the photochromic material film being made of a photochromic material which has a first state dependent on reading light having a first wavelength, where transmittance or reflectance of the material changes so as to enable reading of the recorded information, and has a second state dependent on auxiliary light having a second wavelength, where the transmittance or reflectance changes so as to disable the reading of the recorded information.

2. The optical disc according to claim 1

wherein the second wavelength is longer than the first wavelength.

3. A system for reproducing an optical disc having a recording film with information recorded thereon, a photochromic material film provided adjacent the recording film, the photochromic material film being made of a photochromic material which has a first state dependent on reading light having a first wavelength, where transmittance or reflectance of the material changes so as to enable reading of the recorded information, and has a second state dependent on auxiliary light having a second wavelength, where the transmittance or reflectance changes so as to disabling the reading of the recorded information, comprising:

a first optical system for irradiating a first zone of the optical disc with said reading light;

a second optical system for irradiating a second zone adjacent the first zone with said auxiliary light;

a reproducing system for receiving reading light reflected from the optical disc and for reproducing the recorded information.

4. The system according to claim 3, wherein a beam of the auxiliary light has a sectional shape of a ring around a beam of the reading light.