US 4,989,190 AGranted

Apparatus for seeking a track of an optical disk in which information is recorded

AssigneeOki Electric Industry Co., Ltd.

InventorsShigeru Kuroe, Takayuki Takeda, Masayasu Sato

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Abstract

A track-seeking apparatus for an optical disk drive seeks a target track by counting track crossings according to a track-crossing signal. The track-seeking apparatus also has means for detecting the ID fields on the disk and substituting a simulated track-crossing signal for the track-crossing signal in these fields, thus enabling high-speed seeking without track-count errors.

Claims17

Dependent claims

A track-seeking apparatus for use with an optical disk in which information is recorded in spiral or concentric circular tracks having data fields with pregrooves and identifier fields with pits, comprising:

means for rotating said optical disk;
a pick-up unit for focusing a light beam onto said optical disk, detecting the light reflected from said optical disk, and converting it to at least one pick-up signal;
driver means for moving said pick-up unit parallel to said optical disk and across said tracks;
and
a control circuit for receiving at least one pick-up signal and at least one of control signals, one of said control signals being a seek count signal indicating the number of tracks the light beam must cross to reach a target track, and controlling said driver means according to said at least one pick-up signal and said at least one of control signals so that said driver means causes said pick-up unit to move from a current track to the target track, wherein said control circuit comprises:
track-crossing detection means for detecting track crossings by said light beam and generating a track-crossing signal;
velocity detection means for detecting the pick-up velocity at which said pick-up unit is moving and generating a pick-up velocity signal;
simulation means for generating a simulated track-crossing signal according to said pick-up velocity;
identifier gating means for detecting when said light beam is focused on one of said identifier fields;
a switch controlled by said identifier gating means, for producing a track detect signal that consists of said track crossing signal when said light beam is not focused on one of said identifier fields, and said simulated track-crossing signal when said light beam is focused on one of said identifier fields;
and
means for terminating the seek operation when, as a result of counting the track detect signal, said terminating means determines that said number of tracks indicated by said seek count signal has been crossed.

9 more elements

Dependencies are inferred from the claim text.

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Abstract

means for rotating said optical disk;
a pick-up unit for focusing a light beam onto said optical disk, detecting the light reflected from said optical disk, and converting it to at least one pick-up signal;
driver means for moving said pick-up unit parallel to said optical disk and across said tracks;
and
a control circuit for receiving at least one pick-up signal and at least one of control signals, one of said control signals being a seek count signal indicating the number of tracks the light beam must cross to reach a target track, and controlling said driver means according to said at least one pick-up signal and said at least one of control signals so that said driver means causes said pick-up unit to move from a current track to the target track, wherein said control circuit comprises:
track-crossing detection means for detecting track crossings by said light beam and generating a track-crossing signal;
velocity detection means for detecting the pick-up velocity at which said pick-up unit is moving and generating a pick-up velocity signal;
simulation means for generating a simulated track-crossing signal according to said pick-up velocity;
identifier gating means for detecting when said light beam is focused on one of said identifier fields;
a switch controlled by said identifier gating means, for producing a track detect signal that consists of said track crossing signal when said light beam is not focused on one of said identifier fields, and said simulated track-crossing signal when said light beam is focused on one of said identifier fields;
and
means for terminating the seek operation when, as a result of counting the track detect signal, said terminating means determines that said number of tracks indicated by said seek count signal has been crossed.

9 more elements