Western Digital Assigned Eight Patents

Data storage device employing differential write data signal
and differential write pattern signal
Western Digital Technologies, Inc., Irvine, CA, has been assigned a patent (9,368,132) developed by Hogg, Dennis W., Laguna Hills, CA, for a “data storage device employing differential write data signal and differential write pattern signal.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”A data storage device is disclosed comprising a head actuated over a disk. A first control circuit comprises a pattern detector configured to detect at least one pattern in write data and generate a corresponding multi-state signal, and a transmitter configured to transmit a first differential signal representing the write data and a second differential signal representing the multi-state signal. A second control circuit comprises a receiver configured to receive the first differential signal and the second differential signal, and a write driver configured to generate a write current applied to the head based on the first differential signal and configured to adjust at least one property of the write current based on the second differential signal.“

The patent application was filed on September 4, 2015 (14/846,0191).

Data storage device employing differential write data signal
and differential write pattern signal
Western Digital, Fremont, LLC, Fremont, CA, has been assigned a patent (9,368,131) developed by Tang, Kathy X., Wu, Xiao Z., San Jose, CA, and Pan, Hong, Fremont, CA, for a “data storage device employing differential write data signal and differential write pattern signal.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”A data storage device is disclosed wherein when a first head is over a top disk surface, a first undershoot of a first cross-track profile is closer to an inner diameter of a disk and a second undershoot of the first cross-track profile is closer to an outer diameter of the disk. When a second head is over a bottom disk surface, a second undershoot of a second cross-track profile is closer to the inner diameter of the disk and a first undershoot of the second cross-track profile is closer to the outer diameter of the disk.“

The patent application was filed on April 3, 2015 (14/678,816).

Data storage device characterizing geometry of magnetic transitions
Western Digital Technologies, Inc., Irvine, CA, has been assigned a patent (9,361,939) developed by Eaton, Robert E., San Jose, CA, for a “data storage device characterizing geometry of magnetic transitions.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”A data storage device is disclosed comprising a head and a disk comprising servo information and a reference pattern comprising a plurality of magnetic transitions. The servo information on the disk is processed to actuate the head over the disk, and a read signal is sampled from the head as the head moves across a width of the reference pattern at a substantially constant velocity to generate signal samples. The signal samples are processed to characterize a geometry of the magnetic transitions.“

The patent application was filed on March 31, 2014 (14/230,452).

Disk defect management for data storage device
Western Digital Technologies, Inc., Irvine, CA, has been assigned a patent (9,361,938) developed by Selvaraj, Gomez S., Anaheim, CA, for a “disk defect management for a data storage device.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”A Data Storage Device, (DSD) includes at least one disk surface for storing data and a memory for storing a bitmap buffer. A segment of a disk surface is identified that includes at least one defect region, and a segment bitmap is generated for the segment indicating the at least one defect region within the segment. The segment bitmap is stored in the bitmap buffer.“

The patent application was filed on June 12, 2015 (14/737,822).

Recording read heads with multi-layer AFM layer
Western Digital, Fremont, LLC, Fremont, CA, has been assigned a patent (9,361,913) developed by Zheng, Yuankai, Fremont, CA, and Leng, Qunwen, Palo Alto, CA, for a “recording read heads with a multi-layer AFM layer methods and apparatuses.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”Apparatuses and methods of recording read heads with a multi-layer anti-ferromagnetic, (AFM) layer are provided. The AFM layer has gradient Manganese, (Mn) compositions. A multi-layer AFM layer comprises a plurality of sub-layers having different Mn compositions. An upper sub-layer has a higher Mn composition than an lower sub-layer. Different types of gases may be used to deposit each sub-layer and the flow of each gas may be adjusted.“

The patent application was filed on June 21, 2013 (13/923,991).

Disk drive measuring stroke difference between heads
by detecting difference between ramp contact
Western Digital Technologies, Inc., Irvine, CA, has been assigned a patent (9,355,666) developed by Huang, Yanan, Torrance, CA, Zhang, Zhenyu, Ji, Chuanwen, Irvine, CA, and Phan, Duc T., Saratoga, CA, for a “disk drive measuring stroke difference between heads by detecting a difference between ramp contact.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”A data storage device is disclosed comprising a plurality of disk surfaces including a first disk surface and a second disk surface. A first head is actuated over the first disk surface, and a second head is actuated over the second disk surface. A ramp is located proximate an outer diameter of the disk surfaces. A stroke difference between the first and second heads is measured by moving the first and second heads toward the ramp and detecting when the heads contact the ramp.“

The patent application was filed on June 8, 2015 (14/733,027).

Spin torque oscillator for microwave assisted magnetic recording
with increased damping
Western Digital Technologies, Inc., Irvine, CA, has been assigned a patent (9,355,654) developed by Mallary, Michael L., Sterling, MA, for a “spin torque oscillator for microwave assisted magnetic recording with increased damping.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”A microwave assisted magnetic recording, (MAMR) write head includes a write pole tip, a trailing shield, and a spin torque oscillator between the write pole tip and the trailing shield. The spin torque oscillator may have a field generating layer and a damping layer which is exchanged coupled to the field generating layer.“

The patent application was filed on December 21, 2012 (13/725,731).

Dynamic scaling of LDPC decoder in solid state drive
Western Digital Technologies, Inc., Irvine, CA, has been assigned a patent (9,350,391) developed by Anderson, Kent D., Broomfield, CO, and Krishnan, Anantha Raman, Irvine, CA, for a “system and method for dynamic scaling of LDPC decoder in a solid state drive.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”In some embodiments of the present invention, a data storage device includes a controller and a memory. The data storage device further includes an LDPC encoder and decoder, with the decoder implementing a dynamic precision-rescaling technique for improving performance. In one embodiment, the technique works by rescaling the binary representations of the input log-likelihood ratios, (LLRs) and messages upon activation of decoder-state-based triggers. Various triggering functions are introduced, e.g., checking if the number of output LLRs smaller than a certain limit crosses a threshold, checking if the weight of a syndrome crosses a threshold, etc. This technique offers an improvement in the performance of the decoder.“

The patent application was filed on May 27, 2015 (14/722,673).