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:
Aug. 01, 2000
Filed:
Sep. 30, 1997
Hoya Corporation, Tokyo, JP;
Abstract
In a glass substrate for use in a magnetic recording medium, the glass substrate has a pair of principal surfaces opposite to each other and a peripheral side area contiguous to the principal surfaces. The peripheral side area has a side end wall and intermediate regions between the side end wall and the principal surfaces. In this case, at least one of the intermediate regions and the side end wall is formed by a mirror finished surface which has a surface roughness Ra not greater than 1 .mu.m or a surface roughness Rmax not greater than 4 .mu.m. With this structure, no particles are generated from the peripheral side area because the side end surface of the glass substrate is mirror finished. Consequently, reproduction is performed without reproduction errors because of no generation of a thermal asperity and a head crash can be sufficiently avoided because of no projections which might result from the particles.