Test disk having defect patterns uniformly distributed in recording areas

• US 5,526,341 A
• Filed: 07/26/1994
• Issued: 06/11/1996
• Est. Priority Date: 07/30/1993
• Status: Expired due to Fees

• Current Assignee: Almedio Inc.
• Original Assignee: TEAC Corporation
• Inventors: Yahagi, Yoshio, Shiba, Mitsuo
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): HUBER, PAUL W
• Application Number:
  US08/280,282
• Time in Patent Office: 686 Days
• Field of Search: 369/275.1, 369/275.2, 369/275.3, 369/280, 369/283, 369/54, 369/58, 369/275.4, 430/945, 356/243
• US Class Current: 369/275.1
• CPC Class Codes: G11B 33/10 Indicating arrangements; Warning arrangements G11B15/04, G11B19/04, G11B27/34, G11B27/36 take precedence
• CPC Class Codes: G11B 7/22 Apparatus or processes for the manufacture of optical heads, e.g. assembly
• 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 7/26 Apparatus or processes specially adapted for the manufacture of record carriers

Abstract

A test disk having defect patterns uniformly arranged in recording areas is produced by a production method including: producing a stamper having a plurality of data pits in accordance with test data signals recorded on the test disk; radiating laser light to the stamper by using a laser system so that a plurality of small patterns are produced at laser-light exposed portions along first lines on the stamper, to form interruptions, which interrupt the data pits on the stamper, in accordance with the small patterns; and performing injection molding with plastic material to produce a disk based on the stamper, so that the disk has interruptions corresponding to the interruptions of the stamper, and the interruptions of the disk are included in a recording layer of the disk.

Claims

1. A test disk having defect patterns in recording areas, comprising:

a plurality of recording areas in which test data signals are recorded in a form of data pits; and

a plurality of defect patterns which are uniformly arranged in the recording areas and interrupt the data pits in the recording areas,

said defect patterns comprising a set of lines of small patterns, said small patterns extending along each line in a first direction of the test disk, said lines of said small patterns overlapping each other with respect to a direction perpendicular to the first direction, and said small patterns being shifted relative to one another along the lines.

2. A test disk according to claim 1, wherein said small patterns are formed in the recording areas of the test disk in accordance with laser-light exposed portions of a stamper, said laser-light exposed portions on said stamper being shifted relative to one another in a direction corresponding to the radial direction of the test disk.

3. A test disk according to claim 1, wherein said recording areas comprises a first area having a plurality of music signal tracks in which music signals are recorded and a second area having a plurality of frequency signal tracks in which frequency signals are recorded, and said defect patterns being individually arranged in said first area and in said second area.

4. A test disk according to claim 3, wherein said radially extending defect patterns individually intersect said music signal tracks and said frequency signal tracks, a width of said defect patterns within one track in a circumferential direction is the same, and widths of said defect patterns in the circumferential direction are increased track by track in a stepwise manner.