Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Patent
1998-05-27
2000-09-19
Tran, Thang V.
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
G11B 390
Patent
active
061222380
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The present invention relates to a method of automatically checking disc-shaped information carriers, for instance compact discs. The method involves identifying information carriers, surface checking for possible faults, errors, damage or other defects in the surface of the information carrier, and presenting graphically any defects that are found.
DESCRIPTION OF THE BACKGROUND ART
Automatic compact disc (CD) checking devices are available commercially from a number of suppliers. The purpose of these devices is to check compact discs for faults, errors, damage and/or cosmetic defects with the aid of a defect analysing process, and to sort out unacceptable discs automatically. The majority of these devices include some form of software with which defective sectors can be presented graphically on a computer screen.
A special image recognition camera may be used to ascertain that "correct" compact discs are checked, i.e. it can be ensured that compact discs that carry different titles are not mixed together, because each title has a unique identity which is named or numbered in some way in the label sector of the disc.
Despite the ability to present compact disc defects graphically, the defects are difficult to localize since no directional information is given in the image presented on the screen.
Image recognition cameras are a very expensive pieces of supplementary equipment and it is also difficult to find a mounting location for such cameras in the close proximity of the checking device. Furthermore, such cameras do not provide directional information in the recorded image or picture
The object of the present invention is to eliminate the aforesaid drawbacks.
SUMMARY OF THE INVENTION
In accordance with the inventive method, there is for the purpose of identifying the information carrier carried out a first process for image recognition within a label sector of the information carrier having characters that can be sight-read, and for the purpose of surface checking the information carrier carried out a second process within an information sector of the information carrier having stored data, and discovered defects are presented in the graphic presentation in relation to the label sector, whereby localization of occurrent defects is facilitated by the directional information obtained.
In accordance with a further development of the invention, direction determined images of information carriers are stored on top of one another in the graphic presentation, so that all label sectors from separate information carriers will cover one another, thereby greatly facilitating the analysis of causes of detected defects.
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be described in more detail with reference to the accompanying schematic drawings, in which
FIG. 1 illustrates a compact disc from above;
FIG. 2 is a side view of the disc shown in FIG. 1; and
FIG. 3 illustrates part of a compact disc manufacturing machine.
DETAILED DESCRIPTION OF THE INVENTION
The compact disc shown in FIGS. 1-2 is comprised of the actual transparent polycarbonate disc 20, an aluminium layer 21 and a protective UV lacquer layer 22 (lacquer that has been hardened in ultraviolet light). Seen from the centre of the disc and outwards, the disc includes a centre hole 10, a relatively narrow label sector 11 and a relatively broad information sector 12. The sectors 11 and 12 together form a checking sector in which the disc is checked for defects with the aid of a line camera. The surface layer of the compact disc against which scanning takes place is referenced 23.
The label sector 11 includes visible, readable text, graphics and/or bar codes.
Data is stored in a continuous spiral in the information sector 12. Defect checking takes place primarily in this sector.
The label sector 11 is processed by image recognition, therewith enabling information written into the disc to be compared with information that has earlier been written thereinto and therewith establish whether the compact disc is identical,
REFERENCES:
patent: 5212677 (1993-05-01), Shimote et al.
patent: 5729520 (1958-03-01), Klicker
patent: 5909117 (1999-06-01), Nakadai et al.
patent: 5940174 (1999-08-01), Mueller et al.
Patent Abstracts of Japan, vol. 12, No. 290, P-742 A 63-67550, Pioneer Electronic Corp., Mar. 26, 1988.
M2 Engineering AB
Tran Thang V.
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