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:
May. 20, 1997
Filed:
Oct. 31, 1994
Masaharu Moritsugu, Kawasaki, JP;
Shigeyoshi Tanaka, Kawasaki, JP;
Fujitsu Limited, , JP;
Abstract
Disclosed is an optical disk apparatus having a zero-cross signal generating unit for differentiating a reproduced signal read from an optical disk and outputting a zero-cross signal when the differentiated signal crosses the zero level, and a gate signal generating unit for generating a gate signal using the reproduced signal, wherein a data pulse is outputted when the zero-cross signal is generated while the gate signal is being produced. A clamping circuit clamps the peak of a reproduced signal from an optical disk, an amplitude comparator compares the amplitude of a clamped signal, which is outputted by the clamping circuit, with a reference voltage, and an AGC control unit controls the gain of a variable-gain amplifier by generating a control voltage signal in dependence upon an amplitude difference. The gate signal generating unit generates the gate signal upon comparing the clamped signal outputted by the clamping circuit with a prescribed signal level. A data-pulse output unit outputs the data pulse when the zero-cross signal of the differentiated reproduced signal is generated while the gate signal is being produced.