US 6,687,202 B1Granted

Pickup control device for optical disk drive which adjusts loop gain or determines sample rate

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorsTakahiro Watanabe, Yasushi Imamura, Masaaki Okita, Yuichi Kobayashi

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Abstract

In an optical disk drive having the structure of rotating an optical disk under the alternative control of CAV or CLV, when the optical disk is rotated under the CLV control, the loop gains for at least one of the focus servo system and the tracking servo system for controlling the operation of the pickup of the optical disk drive are adjusted based on angular velocity detected by an angular velocity detector which is also used for rotating the optical disk under the CAV control, and, when the optical disk is rotated under the CAV control, the loop gains for at least one of the focus servo system and the tracking servo system are adjusted based on linear velocity detected by a linear velocity detector which is also used for rotating the optical disk under CLV control. The above structure enables the effective saving of electricity and cost in the optical disk drive.

Claims9

Dependent claims

A pickup control device for an optical disk drive which performs one of operations of writing information on an optical disk and reading information from said optical disk with a pickup of said optical disk drive comprising a focus servo system for controlling focusing operation of said pickup and a tracking servo system for controlling tracking operation of said pickup, said pickup control device comprising:

(a) a first control system which comprises an angular velocity detector for detecting angular velocity of said optical disk, and controls said optical disk based on the angular velocity detected by said angular velocity detector in such a manner that said optical disk enters into a state of rotation at a predetermined constant angular velocity;
and
(b) a second control system which comprises a linear velocity detector for detecting linear velocity of said optical disk at a track position of said optical disk where said pickup is located, and controls the linear velocity in such a manner that the linear velocity enters into a state of predetermined constant linear velocity,
wherein said first control system and said second control system are alternatively operated in such a manner that at least one of
a) a loop gain is adjusted or a sampling rate is determined for said focus servo system and
b) a loop gain is adjusted or a sampling rate is determined for said tracking servo system based on the angular velocity detected by said angular velocity detector of said first control system when said disk is rotated under the control of said second control system, and
wherein at least one of the loop gain for said focus servo system and the loop gain for said tracking servo system is decreased when the linear velocity detected by said linear velocity detector is lower than a reference velocity set in advance, and, at least one of the loop gain for said focus servo system and the loop gain for said tracking servo system is increased when the linear velocity detected by said linear velocity detector is higher than the reference velocity in an occasion of rotating said disk under the control of said first control system.

4 more elements

(a) a first control system which comprises an angular velocity detector for detecting angular velocity of said optical disk, and controls said optical disk based on the angular velocity detected by said angular velocity detector in such a manner that said optical disk enters into a state of rotation at a predetermined constant angular velocity;
and
(b) a second control system which comprises a linear velocity detector for detecting linear velocity of said optical disk at a track position of said optical disk where said pickup is located, and controls the linear velocity in such a manner that the linear velocity enters into a state of predetermined constant linear velocity,
wherein said first control system and said second control system are alternatively operated in such a manner that at least one of
a) a loop gain is adjusted or a sampling rate is determined for said focus servo system and
b) a loop gain is adjusted or a sampling rate is determined for said tracking servo system based on the angular velocity detected by said angular velocity detector of said first control system when said disk is rotated under the control of said second control system, and
wherein at least one of the loop gain for said focus servo system and the loop gain for said tracking servo system is decreased when the angular velocity detected by said angular velocity detector is higher than a reference velocity set in advance, and, at least one of the loop gain for said focus servo system and the loop gain for said tracking servo system is increased when the angular velocity detected by said angular velocity detector is lower than the reference velocity, in an occasion of rotating said disk under the control of said second control system.

4 more elements

(a) a first control system which comprises an angular velocity detector for detecting angular velocity of said optical disk, and controls said optical disk based on the angular velocity detected by said angular velocity detector in such a manner that said optical disk enters into a state of rotation at a predetermined constant angular velocity;
and
(b) a second control system which comprises a linear velocity detector for detecting linear velocity of said optical disk at a track position of said optical disk where said pickup is located, and controls the linear velocity in such a manner that the linear velocity enters into a state of predetermined constant linear velocity,
wherein said first control system and said second control system are alternatively operated in such a manner that at least one of
a) a loop gain is adjusted or a sampling rate is determined for said focus servo system and
b) a loop gain is adjusted or a sampling rate is determined for said tracking servo system based on the angular velocity detected by said angular velocity detector of said first control system when said disk is rotated under the control of said second control system, and
wherein at least one of the sampling rate for operating said digital processing circuit of said focus servo system and the sampling rate for operating said digital processing circuit of said tracking servo system is relatively decreased against rotational velocity of said disk when the angular velocity detected by said angular velocity detector is higher than a reference velocity set in advance, and, at least one of the sampling rate for operating said digital processing circuit of said focus servo system and the sampling rate for operating said digital processing circuit of said tracking servo system is relatively increased against rotational velocity of said disk when the angular velocity detected by said angular velocity detector is lower than the reference velocity, in an occasion of rotating said disk under the control of second control system.

4 more elements

Dependencies are inferred from the claim text.