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:
Mar. 21, 2017
Filed:
May. 25, 2016
Hgst Netherlands B.v., Amsterdam, NL;
Virat Vasav Mehta, San Jose, CA (US);
James William Reiner, Palo Alto, CA (US);
Michael Paul Salo, San Jose, CA (US);
Roger William Wood, Gilroy, CA (US);
HGST Netherlands B.V., Amsterdam, NL;
Abstract
A heat-assisted magnetic recording (HAMR) disk drive has a disk with at least two independent data layers (RLand RL), each data layer storing an independent data stream. At a high laser power both RLand RLare heated to above their respective Curie temperatures and a first data stream is recorded in both RLand RL. At a lower laser power only upper RLis heated to above its Curie temperature and a second data stream is recorded only in RL. The data layers are separated by a nonmagnetic spacer layer (SL) that prevents lower RLfrom being heated to above its Curie temperature at low laser power. The first and second data streams are typically asynchronous. Recorded data is read back from both data streams simultaneously as a composite readback signal. A joint Viterbi detector detects the asynchronous data streams simultaneously from the composite readback signal.