High density optical disc and optical disc player

• US 5,477,527 A
• Filed: 04/14/1994
• Issued: 12/19/1995
• Est. Priority Date: 02/02/1994
• Status: Expired due to Term

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Ito, Toshio, Kano, Yasuyuki, Tsuchiya, Yoichi, Ota, Osamu, Terasaki, Hitoshi, Ichiura, Shuichi, Kato, Seizo, Yamaguchi, Yoshimoto
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): DINH, TAN X
• Application Number:
  US08/227,641
• Time in Patent Office: 614 Days
• Field of Search: 369/275.3, 369/275.4, 369/275.1, 369/275.2, 369/273, 369/274, 369/276, 369/13
• US Class Current: 369/275.4
• CPC Class Codes: G11B 19/26 Speed-changing arrangements; Reversing arrangements; Drive-transfer means therefor
• CPC Class Codes: G11B 7/0037 with discs
• CPC Class Codes: G11B 7/005 Reproducing G11B7/0065 takes precedence
• CPC Class Codes: G11B 7/0938 servo format, e.g. guide tracks, pilot signals
• CPC Class Codes: G11B 7/127 Lasers; Multiple laser arrays lasers per se H01S
• CPC Class Codes: G11B 7/1374 Objective lenses optical objectives per se G02B9/00
• 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 7/24079 Width or depth G11B7/24076 takes precedence
• CPC Class Codes: G11B 7/24085 Pits

Abstract

A high density optical disc having a track pitch of 0.85 μm, a shortest pit length of 0.49 μm, a pit depth of 100 nm, and a pit width of 0.35 μm is rotated at a linear velocity of 2.4-2.8 m/s such that the same is optically reproduced by a laser beam having a wavelength of 635 nm which is converged to a spot size of 0.9 μm by an objective lens having a numerical aperture of 0.6. Accordingly, data is read from the optical disc at a transfer rate of 5.6 Mbps.

Claims

1. An optical disc having a track pitch of 0.7-0.85 μ

m, a pit width of 0.20-0.35 μ

m, and a shortest pit length of 0.42-0.49 μ

m.

2. An optical disc according to claim 1, wherein said track pitch is 0.85 μ

m.

3. An optical disc according to claim 1, wherein said shortest pit length is 0.49 μ

m.

4. An optical disc according to claim 1, wherein said track pitch is 0.85 μ

m, and said shortest pit length is 0.49 μ

m.

5. An optical disc player for reproducing information signals from an optical disc having a track pitch of 0.7-0.85 μ

m, a pit width of 0.20-0.35 μ

m, and a shortest pit length of 0.42-0.49 μ

m, comprising;

a semiconductor laser having a wavelength of 590-670 nm;

irradiating means for irradiating a beam from said semiconductor laser onto said optical disc with a spot size of 0.85-0.95 μ

m; and

a photo-receiving means for receiving a reflected beam from said optical disc and outputting a reproduced signal.

6. A disc player according to claim 5, wherein said irradiating means includes means for irradiating said beam with a spot size of 0.90 μ

m.

7. A disc player according to claim 5, said irradiating means includes a beam condensing means for condensing said beam.

8. A disc player according to claim 6, wherein said beam condensing means includes an objective lens having a numerical aperture of approximately 0.6.

9. A disc player according to claim 5, wherein said irradiating means includes beam condensing means.

10. A disc player according to claim 5, further comprising motor means for rotating said optical disc at a linear velocity of 2.4-2.8 m/s.