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:
Jun. 05, 1990
Filed:
May. 18, 1987
Michiyoshi Nagashima, Hirakata, JP;
Yoshinari Takemura, Osaka, JP;
Matsushita Electric Corp., Ltd., Osaka, JP;
Abstract
A method of reproducing signals formed in slant surfaces of a V-shaped track groove formed in an optical disk. The beam reflected from each slant surface has a portion having a small crosstalk component and a portion having a large crosstalk component, the portions existing separately. The beam reflected from the V-shaped track groove is detected by a photodetector which is composed of two photodetector units. Thus, the output from the first photodetector unit has a small crosstalk component, while the output from the second photodetector unit has a large crosstalk component. The reproduced signal is obtained by subtracting, from a signal formed by amplifying the output of the first photodetector unit, a signal formed by amplifying the output of the second photodetector unit, so that the crosstalk component in the signal from the first photodetector unit is negated by the crosstalk component in the signal from the second photodetector unit, so that the reproduced signal can have a reduced crosstalk component. At the same time, the strictness of requirement for design and positional accuracy of the photodetector is reduced. It is also to arrange such that signals are simultaneously and independently reproduced from adjacent slant surfaces of the V-shaped track groove by a single laser beam spot.