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. 18, 1989
Filed:
Sep. 25, 1987
Applicant:
Inventor:
Hirohisa Yamaguchi, Tokyo, JP;
Assignee:
TEAC Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369 50 ; 369118 ;
Abstract
A disc variation detecting apparatus comprises a light-sensitive element which faces the disc and is positioned together with a light-emitting element in a tangential direction of tracks on the disc. In this configuration, the following relationship is satisfied; d/L.ltoreq..beta./.alpha., where d is a width of a spot of the light beam in its displacement direction formed on the light-sensitive element, L is a length of the light-sensitive element in the displacement direction, .alpha. is an angular variation of the disc corrsponding to the length L, and .beta. is an allowable error angle range upon attitude control of a pickup.