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. 08, 1990
Filed:
Apr. 12, 1984
Sony Corporation, Tokyo, JP;
Abstract
A tracking servo signal is generated for use in an optical disc pick-up system, being particularly advantageous for use when the depth of the pits is greater or less than one-fourth the wavelength of the light beam used to read the disc, in which case diffraction patterns formed by reflected light beams are not symmetric on a photo-detector and typically result in DC-shifted tracking error signals. A first tracking error signal is generated from selected output signals of a number of light-receiving areas of the photo-detector and a second tracking error signal is generated by combining output signals from these light-receiving areas in a pattern different than that used in generating the first tracking error signal. These two tracking error signals are combined so that the resultant signal forms a tracking servo signal that has substantially no DC component.