James W Hopper

US Patent:

55262023, Jun 11, 1996

Filed:

Jun 7, 1995

Appl. No.:

8/482535

Inventors:

John H. Blagaila - Boulder CO
James F. Hopper - Louisville CO
Michael R. Utenick - Englewood CO

Assignee:

Integral Peripherals, Inc. - Boulder CO

International Classification:

G11B 5546

US Classification:

360 7708

Abstract:

An embedded servo system for a disk drive is disclosed. An asymmetrical position sub-field reduces the overhead of the disk position system. The sub-field includes at least two normal frame pairs and only one quadrature frame pair interleaved with one of the normal pairs to form the asymmetrical position sub-field. The prerecorded embedded servo information in each track of the disk includes a multiplicity of different length servo fields, i. e, each track includes at least two types of servo fields where the first type has a first length and the second type has a second length that is different from the first length. The length of a servo field refers to the number of prerecorded bytes in the servo field. The multiplicity of different length servo fields includes a first type having a full track address sub-field and a second type having a modulo track address sub-field in place of the full track address sub-field. In another embodiment, the multiplicity of different length servo fields includes the first and second types of servo fields and a third type of servo field.

US Patent:

54596238, Oct 17, 1995

Filed:

Nov 9, 1993

Appl. No.:

8/150322

Inventors:

John H. Blagaila - Boulder CO
James F. Hopper - Louisville CO
Michael R. Utenick - Englewood CO

Assignee:

Integral Peripeherals, Inc. - Boulder CO

International Classification:

G11B 5596

US Classification:

360 7708

Abstract:

In an embedded servo system for a disk drive, prerecorded servo information in each track of the disk includes a multiplicity of different length servo fields. Each track includes at least two types of servo fields where the first type and the second type have different lengths. The length of a servo field refers to the number of prerecorded bytes in the servo field. The multiplicity of different length servo fields includes a first type having a full track address sub-field and a second type having a modulo track address sub-field in place of the full track address sub-field. One embodiment includes the first and second types of servo fields and a third type of servo field. The third type of servo field includes only track following information and no track address information. The servo fields of differing lengths are interleaved in each track of the disk. The servo fields are chosen to provide a high seek sampling rate in comparison to the required performance and a reduction in the servo overhead.

US Patent:

46269339, Dec 2, 1986

Filed:

Aug 18, 1983

Appl. No.:

6/524426

Inventors:

Nicholas J. Bucska - Louisville CO
James F. Hopper - Louisville CO

Assignee:

Amcodyne Incorporated - Longmont CO

International Classification:

G11B 502
G11B 509

US Classification:

360 51

Abstract:

An apparatus is provided for removing invalid read signal peaks which are detected during a disk read operation. In one embodiment, the apparatus converts the analog read-back signal from the disk into a pair of signals, a raw data signal being indicative of the signal peaks read from the disk and a raw polarity signal being indicative of the polarity of such peaks. The raw data signal is inputted to a phase lock loop, which outputs a strobe signal. The raw data signal and the raw polarity signal are made synchronous with the strobe signal in a reclocking circuit. The data and polarity signals outputted by the reclocking circuit are synchronously applied to a qualifying circuit, the output therefrom being free of invalid data.

US Patent:

43452809, Aug 17, 1982

Filed:

Sep 4, 1980

Appl. No.:

6/183936

Inventors:

John H. Blagaila - Boulder CO
James F. Hopper - Louisville CO

Assignee:

Storage Technology Corporation - Louisville CO

International Classification:

G11B 509

US Classification:

360 49

Abstract:

An address mark detection circuit for use in a magnetic disk data storage unit is disclosed which features a Mealy sequential machine for providing a sequence of logical steps for the testing of sampled data in the search for an address mark; comparison between a given address mark and sampled data is eliminated. In a preferred embodiment, the specific mark to be detected is a first high frequency field followed by a second lower frequency field. The data is repeatedly sampled, and a digital frequency detector is used to provide a two bit signal to the sequential machine for stepping it in a direction corresponding to the frequency of the sample. The circuit allows elimination of means for detection of rotational position sensing information from a dedicated disk surface and elaborate phase-locked-loop circuitry for generating a data rate clocking signal in favor of simple and reliable logic circuitry.