The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 28, 2000
Filed:
Jun. 30, 1999
TEAC Corporation, Tokyo, JP;
Abstract
CD-ROMS of more or less poor quality, such as those having eccentric center holes or uneven weight distributions circumferentially, tend to overload tracking and focusing servos and hence to invite read errors and retries. Each CD-ROM on being loaded into a CD-ROM drive is therefore checked as to its quality preparatory to reading. Either or both of the servos may fail to keep the read beam under control if the disk is not of good quality. Such unlocking of either or both servos is detected in terms of the number of transducer output pulses, the magnitude of transducer output voltage, or the number of read errors, during a complete disk revolution. Disk quality is first checked at four times the standard audio CD speed, then at eight times that speed, and finally at twelve times that speed. Disks of poor quality are read at two times the standard audio CD speed, those of below-average quality at four times that speed, those of above-average quality at eight times that speed, and those of good quality at twelve times that speed.