David D Swanson

US Patent:

6798607, Sep 28, 2004

Filed:

Jan 4, 2002

Appl. No.:

10/035182

Inventors:

Alex Chliwnyj - Tucson AZ
Edward George Butt - Tucson AZ
David Lee Swanson - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5584

US Classification:

360 7712, 360 75, 360 7802

Abstract:

Calibration of magnetic tape servo index positions, which are laterally offset from edges and measured by ratios of dissimilar servo signals. A defined signal is injected into the track following servo to modulate the lateral position of the servo sensor, which is detected by an independent position sensor. Logic converts the detected lateral positions and servo signals to frequency components; selects injected signal frequency components; converts the selected frequency components to lateral positions and servo signals, and fits a curve to the converted lateral positions with respect to the converted servo signals to calibrate the index positions.

US Patent:

6798608, Sep 28, 2004

Filed:

Jan 18, 2002

Appl. No.:

10/050522

Inventors:

Alex Chliwnyj - Tucson AZ
David Michael Davis - Tucson AZ
David Lee Swanson - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5584

US Classification:

360 7712, 360 7804

Abstract:

Initially, from an off-track position at a known side of, and displaced from, a servo track pattern of a tape subject to lateral movement, servo loop logic slews a tape head servo sensor laterally toward the pattern at a rate greater than the maximum rate of lateral movement of the tape. Upon detecting sensed servo signals, the logic decelerates the slewing rate. Upon detecting that the sensed servo signals are within a lock window tolerance, the logic locks a servo loop to a position error signal representing the current lateral position of the servo sensor, thereby acquiring the servo pattern.

US Patent:

6831801, Dec 14, 2004

Filed:

Feb 15, 2002

Appl. No.:

10/075260

Inventors:

Alex Chliwnyj - Tucson AZ
David Michael Davis - Tucson AZ
David Lee Swanson - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 1543

US Classification:

360 71, 2423344

Abstract:

A control system compensates for web tension variation caused by a first spool, (A) determines rotational frequency of the first spool; (B) determines variation in rotational velocity at the second spool which occurs at the (A) first spool frequency; (C) determines the rotational position at the first spool corresponding to the (B) variation in rotational velocity at the second spool; (D) calculates a drive motor profile for the first spool which tends to cancel the (B) variation in rotational velocity at the second spool; and (E) superimposes the (D) drive motor profile on a first spool drive motor at the (C) determined rotational position of the first spool.

US Patent:

6831805, Dec 14, 2004

Filed:

Jun 27, 2002

Appl. No.:

10/185234

Inventors:

Alex Chliwnyj - Tucson AZ
David L. Swanson - Tucson AZ
Steven C. Wills - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5584

US Classification:

360 7712

Abstract:

An apparatus and method to read and/or write information from and/or to a moving magnetic tape comprising one or more servo edges using a tape head comprising (N) servo sensors. Bach servo edge comprises an interface between a first recorded signal and a second recorded signal, where each of the (N) servo sensors detects that first recorded signal and that second recorded signal. The method calculates (N) target PES signals and provides (N) measured PES signals. Using the target and the measured PES signals, the method forms (N) weighted PES signals and averages those (N) weighted PES signals to form a Composite PES signal. That Composite PES signal is used to position the tape head.

US Patent:

6831806, Dec 14, 2004

Filed:

Jun 27, 2002

Appl. No.:

10/185540

Inventors:

Alex Chliwnyj - Tucson AZ
David L. Swanson - Tucson AZ
Steven C. Wills - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5584

US Classification:

360 7712

Abstract:

A method to calibrate a servo sensor disposed on a magnetic tape head disposed adjacent a magnetic tape moving along a tape path. The method measures a maximum and a minimum servo signal ratio, establishes target maximum and minimum servo signal ratios, and determines if the measured servo signal ratios include the target ratios. If the measured servo signal ratios include the target servo signal ratios, then the method forms a filtered servo signal waveform using the measured servo signal waveform. The method then uses the filtered servo signal waveform to calculate a transfer function which is saved for subsequent track following.

US Patent:

6833973, Dec 21, 2004

Filed:

Jun 27, 2002

Appl. No.:

10/185541

Inventors:

Alex Chliwnyj - Tucson AZ
Christopher R. Pandolfo - San Jose CA
David L. Swanson - Tucson AZ
Steven C. Wills - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5584

US Classification:

360 7712

Abstract:

A method to calibrate a servo sensor disposed on a magnetic tape head disposed adjacent a magnetic tape, where that magnetic tape includes at least one servo edge comprising an interface between a first recorded signal and a second recorded signal, whereby the servo sensor is capable of detecting that first recorded signal and that second recorded signal, and whereby an independent position sensor provides an IPS signal comprising the position of the tape head with respect to the tape path. Applicants method determines and uses initial servo signal information and initial IPS signal information to determine an initial transfer function. That initial transfer function is used to determine a positioning signal where the tape head is alternatingly moved in a first direction and an opposing second direction along a first axis as the tape moves along a tape path such that the position of the magnetic head along the first axis as a function of time comprises a periodic function having the positioning signal. Additional servo signals and additional IPS signals are sampled. Those sampled signals are used to determine a second transfer function.

US Patent:

6839197, Jan 4, 2005

Filed:

Jun 27, 2002

Appl. No.:

10/185125

Inventors:

Alex Chliwnyj - Tucson AZ, US
David L. Swanson - Tucson AZ, US
Steven C. Wills - Tucson AZ, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5584

US Classification:

360 7712

Abstract:

A method to calibrate a transducer, whereby the transducer provides a first signal, and whereby a reference provides a reference signal. The first signal is sampled at a sampling rate comprising a reference frequency, and a digital measured first signal waveform is formed. The reference signal is sampled at the sampling rate, and a digital measured reference signal waveform is formed. The real and imaginary components of the measured first signal waveform are determined at (P) harmonics of the reference frequency. A filtered first signal waveform is formed using those real and imaginary components. The real and imaginary components of the measured reference signal waveform are determined at (P) harmonics of the reference frequency. A filtered reference signal waveform is formed using those real and imaginary components. A transfer function is formed using the filtered first signal waveform and the filtered reference signal waveform.

US Patent:

6842304, Jan 11, 2005

Filed:

Jan 8, 2003

Appl. No.:

10/337722

Inventors:

Alex Chliwnyj - Tucson AZ, US
Christopher Robert Pandolfo - Cambridge MA, US
David Lee Swanson - Tucson AZ, US
Steven Carter Wills - Tucson AZ, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 1518

US Classification:

360 721, 3602611

Abstract:

Width of a write track for a magnetic tape head is measured by writing a foreground magnetic track signal on a magnetic tape having a dissimilar background signal. A magnetic tape read head is moved from beyond one edge, laterally across, and beyond the opposite edge of the foreground track signal. Logic detects the read head encountering the one edge and the opposite edge of the foreground track signal; and determines, from an independent position sensor, the width of the foreground track signal as the lateral distance between the lateral position of the read head at one edge, and at the opposite edge of the foreground track signal.