Glass-ceramic substrate for a magnetic information storage medium
US6287663A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 25, 1996 |
| Grant date | Sep 11, 2001 |
| Priority date | — |
| Expiry date | Nov 25, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/252
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
There is provided a glass-ceramic substrate for a magnetic information storage medium having a data zone and a landing zone capable of stably lifting a magnetic head in the landing zone and also capable of reducing the amount of lifting of the magnetic head in the data zone for realizing a high recording density. The landing zone has a multiplicity of projections or depressions formed by irradiation of laser beam. A CO.sub.2 laser or a laser diode pumped solid-state laser can be used for this purpose. The surface roughness (Ra) of a polished surface of the landing zone is within a range from 3 .ANG. to 9 .ANG., height of the projections or depressions is within a range from 50 .ANG. to 300 .ANG., surface roughness (Ra) of the projections or depressions is within a range from 10 .ANG. to 50 .ANG. and interval of the projections or depressions is within a range from 10 .mu.m to 200 .mu.m. A preferable glass-ceramic used is a glass-ceramic of a SiO.sub.2 --Li.sub.2 O--K.sub.2 O--MgO--ZnO--P.sub.2 O.sub.5 --Al.sub.2 O.sub.3 system or a SiO.sub.2 --Li.sub.2 O--K.sub.2 O--MgO--ZnO--P.sub.2 O.sub.5 --Al.sub.2 O.sub.3 --ZrO.sub.2 system. For stable forming of projections or depressions in …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.