Magnetic recording disk with patterned nondata islands with different sizes and opposite polarity and method for making the disk
US8737002B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 26, 2013 |
| Grant date | May 27, 2014 |
| Priority date | — |
| Expiry date | Mar 26, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/59655
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A magnetic recording disk has nondata regions that contain a group of first nondata islands with one area and a magnetization in one perpendicular direction, and a group of second nondata islands with a smaller area and a magnetization in the opposite direction. To magnetize the nondata islands with the proper magnetization directions, a DC magnetic field much greater than the coercive field of the magnetic recording layer is applied in one direction to the entire disk to magnetize all of the nondata islands in the same direction. Then the disk is heated to a predetermined temperature, and while the disk is at this temperature, a second DC magnetic field less than the first DC magnetic field is applied for a predetermined time in the opposite direction to the entire disk. This reverses the magnetization direction of the smaller islands without switching the magnetization of the larger islands.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.