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:
Jul. 30, 1996
Filed:
Oct. 19, 1993
Junji Nakajima, Yokohama, JP;
Kunikazu Ohnishi, Yokosuka, JP;
Tooru Sasaki, Yokohama, JP;
Makoto Miyamoto, Kanagawa-ken, JP;
Masaaki Kurebayashi, Ebina, JP;
Yoshio Suzuki, Yokohama, JP;
Masayuki Inoue, Yokohama, JP;
Hisamitsu Tanaka, Yokohama, JP;
Motoyuki Suzuki, Yokohama, JP;
Yukio Fukui, Tokyo, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A masking type light control layer for decreasing its reflection factor in a high-temperature region is formed on phase pits of an optical disc, and the phase pit depth is set to a predetermined value. A light spot for reproduction is shaped to an elliptical form and two sub-flux beams on the optical disc are spaced by 5/4 track pitch from a principal flux beam in the radial direction of the optical disc. The kind of optical disc is discriminated and reproduction laser power and characteristics of an equalizer circuit are switched in accordance with the type of an optical disc. Through this, a stable servo signal detection can be ensured and repetitive reproduction characteristics can be improved.