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:
Apr. 21, 1998
Filed:
Aug. 09, 1996
Akio Yamakawa, Kanagawa, JP;
Masamichi Utsumi, Chiba, JP;
Sony Corporation, , JP;
Abstract
The type of optical disc having different track pitch is identified simply. A light emitted from the LED 21 is irradiated through a condenser lens 22 onto an optical disc 1. The incident light is diffracted and reflected by the pit 3. When, if the optical disc 1 is a CD, the first order diffracted light is received by the first light receiver 10, on the other hand, if the optical disc 1 is a DVD having a smaller track pitch Pt, the first order diffracted light is received by the second light receiver 11. Therefore, the type of the optical disc 1 is identified based on a light receiving signal of the first light receiver 10 and the second light receiver 11.