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:
Dec. 05, 1995
Filed:
Sep. 23, 1994
Shingo Hamaguchi, Kawasaki, JP;
Yasuyuki Ozawa, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
A track retrieval system retrieves a track of an optical disk based on track cross pulses which correspond to a number of tracks scanned by a scan beam. The track retrieval system includes a pulse shaping circuit for generating a pulse at a zero-crossing of a track error signal which is dependent on a tracking error of the scan beam relative to the track, a masking circuit for outputting track cross pulses by masking an output of the pulse shaping circuit for a predetermined time after the pulse is output from the pulse shaping circuit, so that pulses generated by the pulse shaping circuit within the predetermined time due to chattering are eliminated, a counter for counting the track cross pulses output from the masking circuit and for outputting a counted value, and a control unit for setting the predetermined time in the masking circuit based on a moving speed of the scan beam which is calculated from the counted value output from the counter. A correcting circuit may be provided to output a track cross pulse if the pulse shaping circuit outputs no pulse within a predetermined time, so that a pulse dropout of the track cross pulse is compensated.