Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
1997-12-12
2001-03-20
Huber, Paul W. (Department: 2651)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S053310, C369S053370, C369S124150
Reexamination Certificate
active
06205096
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for testing the quality of an optical disk medium and an optical disk medium; and more particularly, to such a method and apparatus having improved accuracy and reliability.
2. Description of Related Art
Disk media are divided into two groups, magnetic disks and optical disks such as compact disks (CDs). Because of their large storage capacity, the demand for optical disks has rapidly increased.
FIGS. 1A and 1B
illustrate conventional optical disks. The radius L1 of these disks is 60 mm, while the diameter L2 of the center hole is 15 mm.
FIG. 1A
illustrates a conventional prerecorded optical disk. As shown in
FIG. 1A
, a recording area of the optical disk includes a lead-in start point BLI, a main storage area start point BPL, and a lead-out start point BLO. Information is written in the main storage area MSA between the main storage area start point BPL and lead-out start point BLO.
FIG. 1B
illustrates a conventional write-once optical disk upon which no information has been recorded. As with the optical disk of
FIG. 1A
, the optical disk of
FIG. 12
has a recording area, and when information is recorded thereon, this information is recorded in a main storage area MSA. As shown in both
FIGS. 1A and 1B
, an outer area of the recording area is not used to store information. This provides a margin of error with respect to manufacturing defects since defects in the recording area are much more likely to occur in the outer area of the recording area due to the manufacturing techniques used.
With magnetic and magneto-optic disks, conventional quality test methods involved recording signals in the lead-in area or main storage area of the disks, reproducing those test signals, and comparing the test signals to reference signals to determine quality;
These methods have been applied to the quality testing of optical disks. Unfortunately, however, these methods cannot be applied to every optical disk manufactured. For instance, once test data is written into a write-once optical disk, that disk loses its value as a commercial good because it becomes unusable. Accordingly, samples from a plurality of manufactured optical disks are taken and tested according to the above-described methodology.
Besides rendering the sampled disks unusable, these quality testing techniques also prove to be inaccurate and unreliable. Just because the sampled disks may be of sufficient quality does not necessarily mean that the other disks, not sampled, are of sufficiently high quality. Therefore, these tests tend to be inaccurate and unreliable.
These optical disk media also undergo additional quality tests. For instance, the entire surface of the optical disk is displayed by monitoring the scanning of the optical disk surface with a laser beam using a CCD camera. The surface is then visually checked using the display.
Other tests include push/pull, crosstalk, and checking the location of the lead-in start point BLI, main storage area start point BPL, and lead-out start point BLO.
Through the above described test process, mechanical characteristic measurements such as the lead-in start point BLI, the main storage area start point BPL, the lead-out start point BLO, a track and index start point, a test speed, a track pitch, a bow deflection, a warp deflection, a thickness of the optical disk, an angular deflection, a vertical deflection, the radius of the optical disk, and the diameter of the center hole of the optical disk are checked. In addition, signal characteristics such as radial noise, focal noise, push/pull of a tracking signal, data carrier analog, and carrier digital are checked.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a method and apparatus for testing the quality of an optical disk which overcomes the drawbacks and disadvantages discussed above.
Another object of the present invention is to provide a method and apparatus for testing the quality of an optical disk which has improved reliability and accuracy.
A further object of the present invention is to provide a method and apparatus for testing the quality of an optical disk which allows an optical disk to be both quality tested and usable thereafter.
A still further object of the present invention is to provide an optical disk medium which overcomes the drawbacks and disadvantages discussed above.
These and other objects are achieved by providing a method for testing quality of an optical disk medium, comprising: reproducing test data in an outer area of said optical disk medium to produce a test signal, said outer area of said optical disk medium being located circumferentially outside of a main information storage area; and judging quality of said optical disk medium based on said reproduced test signal.
These and other objects are still further achieved by providing an apparatus for testing quality of an optical disk medium, comprising: an optical pick-up reproducing test data in an outer area of said optical disk medium to produce a test signal, said outer area of said optical disk medium being located circumferentially outside of a main information storage area; and judging means for judging quality of said optical disk medium based on said reproduced test signal.
The objects of the present invention are also achieved by providing an optical disk medium, comprising: a main information storage area; and an outer area, circumferentially outside said main information storage area, storing a test signal.
The objects of the present invention are still further achieved by providing a method for recording a test signal in an optical disk medium, comprising: positioning an optical pick-up at an outer area of said optical disk medium to produce a test signal, said outer area of said optical disk medium being located circumferentially outside of a main information storage area; and recording test data in said outer area.
The objects of the present invention are additionally achieved by providing an apparatus for recording a test signal in an optical disk medium, comprising: an optical pick-up; control means for positioning said optical pick-up at an outer area of said optical disk medium, said outer area of said optical disk medium being located circumferentially outside of a main information storage area, and for recording test data in said outer area using said optical pick-up.
Other objects, features, and characteristics of the present invention; methods, operation, and functions of the related elements of the structure; combination of parts; and economies of manufacture will become apparent from the following detailed description of the preferred embodiments and accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures.
REFERENCES:
patent: 5256965 (1993-10-01), Nomura
patent: 5485444 (1996-01-01), Kuhn et al.
patent: 5530687 (1996-06-01), Yamaguchi
patent: 5696756 (1997-12-01), Fujimoto et al.
Kim Hyung-Kyu
Yeo Woon-Seong
Huber Paul W.
LG Electronics Inc.
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