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. 20, 1994
Filed:
Apr. 21, 1992
Gunter Gleim, VS-Villingen-Schwenningen, DE;
Friedrich Fuldner, VS-Villingen-Schwenningen, DE;
Bernd Rekla, VS-Villingen-Schwenningen, DE;
Deutsche Thomson-Brandt GmbH, Villengen-Schwenningen, DE;
Abstract
A regulation circuit which guides a laser beam along the data track of a recording medium includes a first comparator which receives an HF signal and a first threshold signal. The HF signal is normally high and goes low when the laser scans a dirty or damaged area of the recording medium. The first comparator provides a first output signal when the HF signal is less than the first threshold signal. A second comparator receives a tracking error signal and a second threshold signal. The tracking error signal is normally low and goes high when the laser leaves the data track. The second comparator provides a second output signal when the tracking error signal is high and exceeds the second threshold signal. The first and second output signals are input to an AND gate which provides a signal indicating that the laser beam has left the data track when the first and second output signals are both high.