Francis M Lum

US Patent:

D2703483, Aug 30, 1983

Filed:

Sep 8, 1980

Appl. No.:

6/185252

Inventors:

Samuel N. Irwin - Ann Arbor MI
Otto R. Butsch - Ann Arbor MI
Francis Lum - Ann Arbor MI
Juan F. Velazquez - Saline MI

Assignee:

Irwin International, Inc. - Ann Arbor MI

International Classification:

D1402

US Classification:

D14109

US Patent:

44620535, Jul 24, 1984

Filed:

Jul 2, 1981

Appl. No.:

6/280137

Inventors:

Francis Lum - Ann Arbor MI
Bruce Graham - Ypsilanti MI
Samuel N. Irwin - Ann Arbor MI
Juan F. Velazquez - Saline MI

Assignee:

Irwin International, Inc. - Ann Arbor MI

International Classification:

G11B 2108
G11B 2110

US Classification:

360 78

Abstract:

A method for positioning and maintaining a disc head over a desired track centerline on a disc rotatably carried on a disc drive. The distance between the current position of the disc head and the desired track centerline is monitored, and a signal generally proportional to that distance is applied to the disc head moving mechanism to cause the disc head to move toward the track centerline. The control signal is clipped if it exceeds predetermined maximum and minimum values.

US Patent:

46479945, Mar 3, 1987

Filed:

Mar 13, 1984

Appl. No.:

6/589146

Inventors:

Samuel N. Irwin - Ann Arbor MI
Francis Lum - Ann Arbor MI
Michael L. Bolt - Ann Arbor MI
Steven E. Henke - Westland MI
Edmund L. Sokolik - Warren MI
John M. Chambors - Canton MI

Assignee:

Irwin Magnetic Systems, Inc. - Ann Arbor MI

International Classification:

G11B 5027
G11B 554
G11B 2122
G11B 2108

US Classification:

360 85

Abstract:

A miniaturized tape cartridge drive for data processors in accordance with the invention has as peripherally-enclosing main frame providing an access opening for insertion to a tape cartridge and structurally mounting flat, pancake-type drive motors for tape transport and head-positioning translation laterally with respect to the tape, for accessing any of a plurality of adjacent recording tracks on the tape, such motors being disposed in tandem with respect to the cartridge-admitting opening and having their output shafts pointing in opposite directions. The head-positioning motor drives a directly-coupled rotary cam, and a positioning arm extends between the cam and the transducer head to move the head in response to movement of the cam. The positioning arm is pivotally journaled in opposite sides of the main frame upon a transverse pivot axis disposed medially of the arm, such that the arm operates as a fulcrumed lever.

US Patent:

D2700557, Aug 9, 1983

Filed:

Sep 8, 1980

Appl. No.:

6/184788

Inventors:

Samuel N. Irwin - Ann Arbor MI
Otto R. Butsch - Ann Arbor MI
Francis Lum - Ann Arbor MI
Juan F. Velazquez - Saline MI

Assignee:

Irwin International, Inc. - Ann Arbor MI

International Classification:

D1402

US Classification:

D14109

US Patent:

46461752, Feb 24, 1987

Filed:

Apr 5, 1984

Appl. No.:

6/597012

Inventors:

Edmund L. Sokolik - Warren MI
Francis Lum - Ann Arbor MI

Assignee:

Irwin Magnetic Systems, Inc. - Ann Arbor MI

International Classification:

G11B 2108
G11B 2110

US Classification:

360 78

Abstract:

Apparatus and method for decoding of transducer head-positioning information which has been recorded on data-storage media, in particular magnetic tape, and for use of the decoded information to position a transducer head, wherein the transducer head reads the recorded information and its output signals are sampled at predetermined times to determine their magnitude and a digital representation of such magnitude is obtained by timing an interval during which a reference source increases at a known rate from a first value to a second value whose difference corresponds to the detected magnitude of the transducer output signals. The timed interval is outputted in the form of a digital count value which is thus representative of the head-positioning information read out from the data storage media, and the digital signal provided by such count value is then used in positioning, or repositioning, the transducer head in a representative manner.

US Patent:

44727500, Sep 18, 1984

Filed:

Jul 2, 1981

Appl. No.:

6/280138

Inventors:

Marlin K. Klumpp - Ann Arbor MI
Joseph H. Mueller - Tecumseh MI
Francis Lum - Ann Arbor MI
Samuel N. Irwin - Ann Arbor MI

Assignee:

Irwin Magnetic Systems, Inc. - Ann Arbor MI

International Classification:

G11B 2108
G11B 2110

US Classification:

360 78

Abstract:

A recording member for digital data, particularly a recording tape, has a plurality of generally parallel, closely-spaced recording tracks which each contain pre-recorded track-identifying and transducer-positioning servo information, as well as defined data-recording areas. The pre-recorded track-identifying information preferably comprises a digitally-encoded individual track address, and the servo information comprises separate bursts used in centering the transducer upon a particular track. Preferably, each such track has a dedicated area at its beginning, end, or both, which contain continuous repetitions of such positioning information, there being no data areas in such dedicated portions. Digital encoding of track addresses utilizes binary-type code format, accomplished by defining a binary "zero" as a recorded burst present at a first number of sampling points, and defining a binary "one" as a burst present at a second number of sampling points of a second duration. The pre-recorded positioning information includes certain non-recorded "gaps" which serve as initializing signals, and the preferred system for utilizing the pre-recorded, servo-controlled record member utilizes peak-detection and minimum-threshold techniques to accurately distinguish unrecorded gaps from noise, or the like, on the one hand, and to distinguish coded signal bursts from other possible recorded signals, or noise, on the other hand.

US Patent:

45860947, Apr 29, 1986

Filed:

Mar 13, 1984

Appl. No.:

6/589007

Inventors:

John M. Chambors - Canton MI
Francis Lum - Ann Arbor MI

Assignee:

Irwin Magnetic Systems, Inc. - Ann Arbor MI

International Classification:

G11B 554

US Classification:

360 77

Abstract:

A method and apparatus for initializing a data-recording media, particularly tape, by use of the same type of media drive used for data-recording purposes, in which the actual edge of the recordable field on the media is first located by a test read/write process and the media is then transported in a succession of passes across the transducing head, during each of which the head is periodically and selectively energized to write mutually-spaced marker bursts and servo-positioning bursts, with the transducing head being moved open-loop a distance corresponding to a half-track width between each media transport. During the first such pass, the marker bursts and servo-positioning bursts are located on the basis of tape travel distance, and on successive passes burst location is determined by sensing the previously-recorded marker and servo bursts and timing-out a predetermined distance therefrom by use of an internal clock. In the case of tape-form media, tape transport and transducer-positioning is carried out in a serpentine pattern.