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. 29, 1997
Filed:
Jul. 29, 1994
Hiroshi Oki, Yokohama, JP;
Nikon Corporation, Tokyo, JP;
Abstract
An optical recording medium has a track format with a track pitch smaller than a diffraction limit of a light spot so as to realize an increased capacity and a higher density. A guide groove for tracking purposes is formed along each of the concentrically or spirally formed tracks in a periodic intermittent pattern with respect to a circumferential direction of the optical recording medium. The intermittent patterns of the guide grooves adjoining each other with respect to a radial direction of the optical recording medium are displaced in phase from each other. A light spot of a diameter greater than the track width is projected onto the optical recording medium in rotation and the position of the light spot is servo-controlled in the track width direction in such a manner that a light quantity distribution with respect to the track width direction of a reflected or transmitted light of the light spot diffracted by the selected guide groove maintains its symmetry in the track width direction.