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. 16, 1991
Filed:
Sep. 28, 1988
Tetsuya Kondo, Yokohama, JP;
Noboru Kawai, Komae, JP;
Victor Company of Japan, Ltd., Yokohama, JP;
Abstract
An information recording disk for recording an information signal along a track defined by a depression on the disk as a change of physical property of a recording material deposited on the track comprises a disk-shaped glass substrate made of a glass and carries a groove corresponding to the track. The groove has a surface roughness substantially smaller as compared to the surface roughness caused at a bottom surface of a groove on a silica glass substrate when both the disk-shaped glass substrate and silica glass substrate are dry-etched under same conditions. The disk-shaped glass substrate comprises SiO.sub.2 component and one or both of Al.sub.2 O.sub.3 and BaO components with substantially no alkali components. Further, a recording layer comprised of the recording material which changes in physical property responsive to a projected energy beam is deposited on the substrate such that the depression is formed in correspondence with the track.