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:
May. 27, 1986
Filed:
Sep. 26, 1983
Shigeo Kubota, Tokyo, JP;
Kenji Shintani, Tokyo, JP;
Sony Corporation, Tokyo, JP;
Abstract
In an optical reproducing apparatus a divergent beam from a semiconductor laser light source is collimated to form a parallel light beam that is converged by an objective lens and focussed on an optical record medium. The light beam is reflected by the optical record medium and introduced into a signal photodetector so as to provide a reproduced signal. A phase type diffraction grating between the semiconductor laser light source and a beam splitter separates the laser beam from the semiconductor laser light source into zero, plus first and minus first order diffracted beams. A pair of tracking photodetectors receive reflected beams of the plus first and minus first order diffracted beams reflected by the optical record medium and then by the beam splitter. A concave lens located between the photodetectors and the beam splitter facilitates convenient positioning of the photodetectors so that a tracking error signal can be obtained by calculating the difference between the outputs of the first and second tracking photodetectors.