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:
Nov. 20, 1984
Filed:
Sep. 11, 1981
Kenji Koishi, Suita, JP;
Tomio Yoshida, Katano, JP;
Isao Satoh, Neyagawa, JP;
Shunji Harigae, Neyagawa, JP;
Matsushita Electric Industrial Co., Ltd., Kadoma, JP;
Abstract
A track searching system for an optical information recording and reproducing apparatus in which a disc-like information carrier provided with concentric or spiral guide tracks of a channel-like configuration is used as an information recording and storing means and adapted to be scanned by a light beam for recording or retrieval of information. Light flux reflected by the information carrier and presenting variable distribution of light intensity is received by paired photoelectric elements. A difference signal and a sum signal derived from the output signals from the photoelectric elements or a reproduced RF signal representative of reproduced information undergo phase comparison processing, the result of which is utilized for determining the direction and number of guide tracks traversed by the scanning light beam. A desired track is searched and accessed with high accuracy at a high speed for assuring a positive and rapid information recording or retrieval at the desired track regardless of eccentricity of the information carrier, variations in the scanning speed, and the presence or absence of a recorded track.