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EP0717399A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Head tracking system in a disk drive

Assignee: NEC Corp
•
Filing: 1995-12-14
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Granted: —
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Expires: 2015-12-14
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Abstract

Abstract A head tracking system includes an optical head mounting thereon a focusing lens for generating an optical spot on a disk file. The system retrieves a normalized speed profile including a first section for acceleration and a second section for deceleration based on a seeking stroke. The focusing lens is first moved based on the corrected speed profile, which is obtained by multiplying the deceleration in the normalized speed profile by a correction factor. The optical head is then moved in a feed-back loop so that the lens position error becomes zero which is deviation of the focusing lens relative to a reference position of the optical head. The correction factor is calculated by a maximum lens position error obtained during a previous seeking operation. A high-speed, stable and accurate seeking operation can be obtained even in the case of inclination of the optical head, vibration of the focusing lens or fluctuation of the supply voltage.

Inventors

  • 👤 Takeshi c/o NEC Corporation Sasaki

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-08 15:06
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/085; G11B7/08505; G11B7/08529; G11B11/00; G11B11/10; G11B11/105; G11B11/1055; G11B11/10556; G11B11/10563

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 175 words
A head tracking system for an optical disk drive comprising: an optical head (22) mounting thereon a focusing lens (21) for generating an optical spot on an optical disk; a lens position error sensor (23) for detecting a lens position error representing deviation of said focusing lens (21) with respect to a reference position of said optical head (22); a first actuator (20) for moving said focusing lens relative to said optical head (22) in a radial direction of the optical disk based on a first speed profile; and a second actuator (19) for moving said optical head (22) relative to the optical disk in the radial direction based on the lens position error, characterized by; a first means for calculating a correction factor based on the magnitude of said lens position error during a first seeking operation; and a second means for correcting a normalized speed profile based on said correction factor obtained during the first seeking operation to generate said first speed profile for a second seeking operation following the first seeking operation.
Claim 2
Dependent Claim 34 words
A head tracking system as defined in Claim 1 wherein said normalized speed profile is retrieved from a memory storing a normalized speed profile table listing normalized speed profiles in association with seeking strokes.
Claim 3
Dependent Claim 42 words
A head tracking system as defined in Claim 1 or 2 wherein said normalized speed profile includes a first profile section for accelerating a speed with a constant acceleration and a second profile section for decelerating a speed with a constant deceleration.
Claim 4
Dependent Claim 31 words
A head tracking system as defined in one of Claims 1 to 3 wherein said second means generates said corrected speed profile by multiplying said constant deceleration by said correction factor.
Claim 5
Dependent Claim 33 words
A head tracking system as defined in one of Claims 1 to 4 wherein said first means calculates said correction factor based on a maximum lens position error during the first seeking operation.
Claim 6
Dependent Claim 37 words
A head tracking system as defined in one of Claims 1 to 5 wherein said correction factor is smaller than one when said maximum lens position error during the first seeking operation is larger than a threshold.
Claim 7
Dependent Claim 41 words
A head tracking system as defined in one of Claims 1 to 6 wherein said correction factor is larger than one when said maximum lens position error is smaller than said threshold for a predetermined number of the first seeing operations.
Claim 8
Dependent Claim 28 words
A head tracking system as defined in one of Claims 1 to 6 wherein said threshold is determined based on the seeking stroke during the second seeking operation.
Claim 9
Dependent Claim 47 words
A head tracking system as defined in one of Claims 1 to 7 wherein said correction factor is obtained by multiplying a first correction factor obtained in the first seeking operation by a second correction factor obtained in a third seeking operation preceding the first seeking operation.

References Cited (Backward Citations)

JPS61177641A Cited

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