Seagate Technology Incorporated

Dennis D Duffy

Lealon Ray McKenzie

Robert D Cronch

Michael Edward Baum

Philip Ray Woods

Jeffrey Alan Miller

Brian W Sudman

Fereidoon Heydari

One embodiment of the present invention is directed to a method of aligning servo wedges of a plurality of disc surfaces in a disc drive. This process of aligning servo wedges in a disc drive includes writing multiple servo wedges, one adjacent another, continuously across an entire circumference of each disc surface. Subsequently, one of the disc surfaces is designated the master surface. Every n servo wedge on the master surface is then designated as a master wedge, where n is a positive integer. Next, the servo wedges on the non-master surfaces which are most closely axially aligned with the master wedges are selected. Subsequently, all of the non-selected and non-master wedges are erased.

Method of aligning servo wedges in a disc drive

A disc drive is disclosed having servo information written to one or more discs of the disc drive at a frequency that varies for each of the tracks defined on the disc, the servo information read by and used to control the position of an associated head of the disc drive. The servo information is preferably constant density and arranged as a plurality of servo strips extending radially from an inner to an outer diameter of the disc, each servo strip comprising a plurality of servo fields, the servo fields defining the tracks on the disc.

Constant density servo information in a disc drive

An apparatus and associated method are disclosed for storing servo information on a rotatable disc of a disc drive at a frequency that varies for each track defined on the disc. A servo track writing system is provided which generates a fixed frequency pattern clock signal that indicates the appropriate angular locations on the disc at which the servo information is to be written, and a servo write clock signal having a selectively variable frequency at which the servo information is written. A reset pulse temporarily suspends and restarts the servo write clock signal so as to be in phase with the pattern clock signal at the initiation of the output of the servo information.

Writing servo information to a disc drive at a constant density

A hard disc drive having a digital servo system for controlling the position of a servo head on a dedicated servo surface. The servo surface is formatted in a series of consecutive frames along concentric tracks, each frame passing the servo head in a time that defines a sampling interval for the servo system. The frames contain track address and position fields for locating the servo head and location can be effected in relation to limited or extended fine control regions about the tracks via signals transmitted to a position circuit utilized to generate a servo position error from the position field. The position circuit generates a track phase code for checking track addresses generated by a track address circuit used to generate a track address from the address field. Servo routines are carried out by a servo microcomputer using control equations, stored in the servo microcomputer, having coefficients stored in a system microcomputer that transmits the coefficients with command to carry out servo operations. Writing of data to data tracks is disabled when an effective head to track distance, defined in relation to actual distance and head speed exceeds an on track threshold.

Hard disc drive with improved servo system

A circuit for slimming signals read signals from a read/write head of a rotating disk data storage device. A low-pass filter and a high-pass filter are connected in parallel to the read signal from the read/write head. These filters each have a variable gain amplifier connected to their respective output ports. The gain of each of the variable gain amplifiers is programmably adjusted in accordance with preselected criteria. A summing circuit is connected to the outputs of the variable gain amplifiers to generate a slimmed read signal. A multi-pole low pass filter has an input port coupled to the output port of the summing circuit.

Differential slimmer

An index pulse generator in a magnetic storage system reads data from a surface in the magnetic storage system and produces an index pulse. An incrementing sequence of non-zero codes, with redundancy, is written in a series of consecutive servo data frames, immediately preceding, leading up to, and including a specific servo index frame. Error tolerant circuitry reads and decodes the servo frame data, maintains a count of non-zero codes encountered, and generates an index pulse provided that both the desired count of non-zero codes has been reached and that a minimum number of matches between the non-zero frame counter and the actual frame decodes has been satisfied.

Growing community of inventors

Oklahoma City, OK, United States of America

Dennis D Duffy