Hoya Assigned Patent

Hoya Corp., Tokyo, Japan, has been assigned a patent (11,211,090) developed by Azuma, Shuhei, Akishima, Japan, for “magnetic-disk glass substrate, magnetic-disk glass substrate intermediate, and method for manufacturing magnetic-disk glass substrate.“

The abstract of the patent published by the U.S. Patent and Trademark Office states: “A magnetic-disk glass substrate contains an alkaline earth metal component as a glass composition and includes a pair of main surfaces, and an outer circumferential side edge surface that is a mirror surface. The outer circumferential side edge surface includes a surface having a roughness percentage of 40% or more when a bearing ratio of a roughness cross-sectional area is 50% in a bearing ratio curve of roughness cross-sectional areas obtained when a surface roughness of the outer circumferential side edge surface obtained after the outer circumferential side edge surface is etched by 2.5 .mu.m is measured.”

The patent application was filed on May 27, 2020 (16/884,931).