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. 28, 1998
Filed:
Oct. 17, 1996
Tsutomu Mochizuki, Chiba, JP;
Sony Corporation, , JP;
Abstract
A disc-thickness-and-warp detecting apparatus includes a light source for emitting rays onto a peripheral portion of an optical disc; a photo-detector having a plurality of photo-detecting portions separated corresponding to the direction of tracks formed on the disc, for detecting rays emitted from the light source and reflected by the disc; an adding circuit for generating a sum-signal by adding the detection-signals from the respective photo-receiving portions; and a subtracting circuit for generating a difference-signal by performing the subtraction of the detection-signals from the respective photo-receiving portions. The apparatus uses such common detecting means to detect the distance between the disc surface and the signal-recording surface and a warp of the disc.