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:
Sep. 08, 1992
Filed:
Jul. 30, 1990
Tohru Nakamura, Osaka, JP;
Hideki Aikoh, Osaka, JP;
Masayuki Shinoda, Osaka, JP;
Noboru Kikuchi, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An optical head equipped with a tracking error detector to obtain a tracking error signal for tracking servo. The detector includes a photodetector having a light-detecting region on which a light spot with a predetermined diameter is formed by a reflected light beam from a recording medium. The region is divided by a first division line into two which are further divided by second and third division lines so as to form first to fourth subregions, the first and second subregions being adjacent to each other with the first division line being interposed therebetween, the third subregion being adjacent to the first subregion, and the fourth subregion being adjacent to the second subregion. The separation between the second and third division lines is determined so that the sum of the light receiving quantities of the first and fourth subregions is substantially equal to the sum of the light receiving quantities of the second and third subregions when the objective lens is shifted from its neutral position. Electric signals produced in correspondance with the light receiving quantities are supplied to a differential amplifier to take a difference between a sum signal of the signals due to the first and fourth subregions and a sum signal of the signals due to the second and third subregions.