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:
Oct. 13, 1987
Filed:
Jun. 17, 1985
Applicant:
Inventors:
Tomio Yoshida, Katano, JP;
Yoshinobu Nakata, Ikoma, JP;
Shunji Ohara, Higashiosaka, JP;
Toshio Satoh, Hirakata, JP;
Assignee:
Matsushita Electric Industrial Co., Ltd., Kadoma, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369 44 ; 369 46 ; 369110 ; 250202 ;
Abstract
In an optical recording and playback disc apparatus, two light beams (l, m) are focused by a common focusing lens (108) onto an information track (51) of the optical recording disc, and the focused light means (l, m) form two light spots (L, M), the position thereof being controlled by a first tracking servo loop (115, 116 and 117), and furthermore, one (M) of the light spots is independently controlled from the other light spot (L) by a second tracking servo loop (120, 121 and 122).