Gerald J Smart

US Patent:

51213737, Jun 9, 1992

Filed:

Oct 25, 1989

Appl. No.:

7/426357

Inventors:

Mark A. Barton - Rochester NY
Daniel L. Nelson - Penfield NY
Gerald J. Smart - Penfield NY

Assignee:

Eastman Kodak Company - Rochester NY

International Classification:

G11B 2108

US Classification:

369 4428

Abstract:

Track jumping in the present system is accomplished by using a two step track jump method which accelerates the tracking actuator toward the desired track at maximum acceleration and then decelerates the tracking actuator at a maximum deceleration so that the desired track is reached in a minimum amount of time without the actuator ringing. A matrix containing the times for each jump pulse from track X to track Y is recorded. The matrix table is updated after each jump to compensate for variance factors. The table is stored in memory which allows the system to become more accurate with each jump. If the actuator falls short of the desired position, the jump pulse next applied is lengthened slightly. If the jump pulse causes the actuator to overshoot, the desired position the jump pulse is shortened for the next jump.

US Patent:

54405343, Aug 8, 1995

Filed:

Jan 10, 1994

Appl. No.:

8/179474

Inventors:

Clarke K. Eastman - Rochester NY
Daniel L. Nelson - Penfield NY
Gerald J. Smart - Penfield NY

Assignee:

Eastman Kodak Company - Rochester NY

International Classification:

G11B 709

US Classification:

369 4427

Abstract:

A method and apparatus for, in an optical data recorder, maintaining a recording light beam in an on-track position on a recording medium. In the apparatus an optical head has a tracking arrangement movable in a direction parallel to the recording medium for changing the tracking position of the recording light beam on the recording medium. The method comprises the steps of: i)detecting light reflected from the optical recording medium and producing a corresponding tracking error signal; ii) generating a mark formation effectiveness signal for each of a plurality of trial tracking positions, each mark formation effectiveness signal being associated with a given value of the tracking error signal; iii) determining the mark formation effectiveness signal corresponding to an on-track position and determining an on-track the value of the associated tracking error signal; and iv)during data recording periods, in response to the tracking error signal, adjusting the position of the movable tracking means so that the on-track value of the tracking error signal is maintained.

US Patent:

55616453, Oct 1, 1996

Filed:

Aug 21, 1995

Appl. No.:

8/517306

Inventors:

Clarke K. Eastman - Rochester NY
Daniel L. Nelson - Penfield NY
Gerald J. Smart - Penfield NY

Assignee:

Eastman Kodak Company - Rochester NY

International Classification:

G11B 709

US Classification:

369 4429

Abstract:

A method and apparatus for, in an optical data recorder, focusing a recording light beam on a recording medium. In the apparatus, an optical head has focusing means movable in a direction perpendicular to the recording medium for changing the focus position of the recording light beam on the recording medium. The method comprises the steps of: i) detecting light reflected from the optical recording medium and for producing a corresponding focus error signal; ii) generating a mark formation effectiveness signal for each of a plurality of trial focus positions, each mark formation effectiveness signal being associated with a given value of the focus error signal; iii) determining the mark formation effectiveness signal corresponding to an in-focus position and determining an offset value of the associated focus error signal; and iv) during data recording periods, in response to the focus error signal, adjusting the position of the movable focusing means so that the value of the focus error signal is maintained at the offset value.

US Patent:

54368804, Jul 25, 1995

Filed:

Jan 10, 1994

Appl. No.:

8/179476

Inventors:

Clarke K. Eastman - Rochester NY
Gerald J. Smart - Penfield NY
Peter J. Spyra - Churchville NY

Assignee:

Eastman Kodak Company - Rochester NY

International Classification:

G11B 700

US Classification:

369 54

Abstract:

The present invention provides an apparatus and method for controlling laser power in an optical recording system. A recording system in accordance with the present invention includes an optical source for supplying an incident write signal to an optical medium, such that data may be recorded on the medium during an incident write pulse as a mark having a distinct reflectivity; a detector for detecting a reflection the incident write signal from the medium to provide a reflected write signal; a generator for generating a mark formation effectiveness signal from a reflected write pulse in the reflected write signal, to provide an indication of the quality of the mark; an error signal generator for generating an error signal from the mark formation effectiveness signal and a target value of the mark formation effectiveness signal; and a controller for controlling a write power level of the optical source by providing a partial correction of variation in the error signal. The quality of data recorded in the presence of certain types of system degradations, such as laser defocus and optical media tilt, is improved. The present invention also provides techniques for determining write power control voltage and error signal voltage limits, and updating the limits using an incident write signal optical detector.

US Patent:

51213745, Jun 9, 1992

Filed:

Oct 25, 1989

Appl. No.:

7/426356

Inventors:

Mark A. Barton - Rochester NY
Daniel L. Nelson - Penfield NY
Gerald J. Smart - Penfield NY

Assignee:

Eastman Kodak Company - Rochester NY

International Classification:

G11B 2110

US Classification:

369 4429

Abstract:

The present method operates upon an optical disk type servo-system of the type having an optical tracking servo for maintaining a lens centered over a track on a disk and a tracking position servo for moving an optical head's lens to a desired position. Included within such a system is an eccentricity sub-system for providing a compensating sine wave signal for reducing errors in tracking due to disk decentering. The present method automatically adjusts the gain in one of the servos to match the gain appearing in the other servo so as to improve the smoothness of control when switching between the servos.

US Patent:

54467160, Aug 29, 1995

Filed:

Jan 10, 1994

Appl. No.:

8/179394

Inventors:

Clarke K. Eastman - Rochester NY
James A. Perconti - Rochester NY
Gerald J. Smart - Penfield NY
Peter J. Spyra - Churchville NY

Assignee:

Eastman Kodak Company - Rochester NY

International Classification:

G11B 700

US Classification:

369 54

Abstract:

The present invention provides an apparatus and method for controlling laser power in an optical recording system in the presence of multiple system degradations. A recording system in accordance with the present invention includes an optical source for supplying an incident write signal to an optical medium, such that data may be recorded on the medium during an incident Write pulse as a mark having a distinct reflectivity; a structure for detecting a reflection of the incident write signal from the medium to provide a reflected write signal; means for generating a mark formation effectiveness signal from a reflected write pulse in the reflected write signal, to provide an indication of the quality of the mark; means for generating an error signal from the mark formation effectiveness signal and a target value of said mark formation effectiveness signal; and means for controlling a write power level of the optical source by providing a partial correction of a first type of variation in the error signal and a full correction of a second type of variation in the error signal. The first type of variations may be due to high frequency system degradations such as laser defocus and optical media tilt, while the second type of variation may be due to low frequency variations, such as changes in optical source wavelength or media sensitivity.

US Patent:

50200453, May 28, 1991

Filed:

Dec 19, 1988

Appl. No.:

7/286094

Inventors:

Gerald J. Smart - Penfield NY
Daniel L. Nelson - Penfield NY

Assignee:

Eastman Kodak Company - Rochester NY

International Classification:

G11B 700

US Classification:

369 4429

Abstract:

A focus acquisition servo system and method which speeds the acquisition process by focusing on the recording media of an optical disk while the disk is coming up to speed. Focus is accomplished by jumping the focus actuator from a start position close to the focus position and by ramping the focus actuator away from the surface of the disk while monitoring focus gain. When the focus gain reaches a peak amplitude the disk is in rough focus, ramping is stopped and the focus servo system is activated to lock the focus actuator onto a fine focus on the disk's recording media.