HGST Assigned Three Patents

PMR disk having permeability gradient
HGST Netherlands B.V., Amsterdam, Netherlands, has been assigned a patent (8,982,510) developed by Choe, Gunn, San Jose, CA, for a “perpendicular magnetic recording disk having a permeability gradient.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”Perpendicular magnetic recording disks and methods of fabricating perpendicular magnetic recording disks are described. The perpendicular magnetic recording disk includes a soft magnetic underlayer, (SUL) structure, an interlayer, and a perpendicular magnetic recording layer. The SUL structure has an increased permeability from an inner radius of the disk to an outer radius of the disk. As a result, the magnetic write width, (MWW) on the tracks of the disk is substantially uniform throughout the disk.“

The patent application was filed on November 5, 2007 (11/935,189).

HDD with write assist based on detected conditions
HGST Netherlands B.V., Amsterdam, Netherlands, has been assigned a patent (8,982,502) developed by Morinaga, Akira, Chigasaki, Japan, Nishiyama, Nobumasa, Yokohama, Japan, and Nagasaka, Keiichi, Isehara, Japan, for a “hard disk drive with write assist based on detected conditions.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”In one embodiment, a hard disk drive includes a magnetic disk medium, a magnetic head adapted for writing data to the magnetic disk medium, a mechanism, such as a detection circuit) adapted for detecting at least one recording condition of drive current provided to the magnetic head during writing operations, and an energy conversion element for controlling at least one recording characteristic of the magnetic head in response to the at least one detected recording condition. According to another embodiment, a method includes writing data to a magnetic medium using a magnetic head, detecting at least one recording condition of drive current provided to the magnetic head during the writing, and controlling at least one recording characteristic of the magnetic head during the writing using an energy conversion element in response to the at least one detected recording condition.“

The patent application was filed on December 12, 2011 (13/323,704).

Disk drive with different synchronization fields and synchronization marks
in data sector preambles in adjacent data tracks
HGST Netherlands B.V., Amsterdam, Netherlands, has been assigned a patent (8,982,491) developed by Coker, Jonathan Darrel, Galbraith, Richard Leo, Hanson, Weldon Mark, Oenning, Travis Roger, Rochester, MN, and Surendran, Srinivasan, Irvine, CA, for a “disk drive with different synchronization fields and synchronization marks in the data sector preambles in adjacent data tracks.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”A hard disk drive has disks with data sector preambles that allow for inter-track interference. The same data sector preamble is used for all data sectors in a track but the preamble in each track is different from the preamble in radially adjacent tracks. In a first embodiment each preamble includes a synchronization field, SF) and synchronization mark, SM) that are the same in each track but different from the SF and SM in radially adjacent tracks. Only two unique SFs and two unique SMs are required, with the two SFs and two SMs alternating in radially adjacent tracks. In a second embodiment the preambles are “integrated”, meaning that the preamble is a sequence of bits that does not include separate dedicated fields, like SF and SM. The preamble bit sequences are decoded using matched filters to provide bit synchronization and start-of-data information.“

The patent application was filed on September 19, 2013 (14/031,970).