Tilt control for optical disk and tilt control method

• US 7,190,645 B2
• Filed: 02/10/2003
• Issued: 03/13/2007
• Est. Priority Date: 02/25/2002
• Status: Expired due to Fees

• Current Assignee: Funai Electric Co., Ltd.
• Original Assignee: Funai Electric Co., Ltd.
• Inventors: Yoshimoto, Tadafumi
• Primary Examiner(s): Wellington; Andrea
• Assistant Examiner(s): CHU, KIM KWOK
• Application Number:
  US10/361,031
• Publication Number:
  US 20030161232A1
• Time in Patent Office: 1,492 Days
• Field of Search: 369/44.32, 369/44.34, 369/44.37, 369/44.41, 369/53.19, 369/112.05
• US Class Current: 369/44.32
• CPC Class Codes: G11B 7/0945 Methods for initialising servos, start-up sequences
• CPC Class Codes: G11B 7/0956 to compensate for tilt, skew, warp or inclination of the disc, i.e. maintain the optical axis at right angles to the disc

Abstract

At the initialization, a tilt mechanism 9 is activated in a state where an optical pick-up 3 is fixed, and set up at a position where an E-F phase difference obtained in a signal processing portion 4 is 180°. Thereafter, a reproducing operation is started. During the reproducing operation, the tilt mechanism 9 is not activated and the focus control is made with the focus servo by moving the optical pick-up 3 up or down, while the level of a focus error signal is within a certain range. Further, if the level of focus error signal is beyond the certain range because the optical disk 1 is greatly inclined, the tilt mechanism 9 is activated to cause the optical disk 1 to come closer to the optical pick-up 3 to enable the control of the focus servo.

Claims

1. A tilt control device for an optical disk comprising:

an optical pick-up for reading the information recorded on the optical disk by applying a light beam consisting of a main beam and two sub-beams onto the optical disk,

a tilt mechanism for correcting an inclination of the optical disk,

a tilt motor for activating said tilt mechanism,

detecting means for detecting the amount of inclination of the optical disk, and

a tilt control portion for controlling said tilt motor on the basis of the detection result of said detecting means, wherein

said detecting means involves the use of a focus error signal obtained from a reflected light of the main beam and an E-F phase difference signal obtained from the reflected lights of two sub-beams, instead of a tilt sensor;

said detecting means includes two light receiving sections each of which receives the sub-beam and generates the E-F phase difference therebetween;

at the initialization, said tilt mechanism is set up at a position where the E-F phase difference is 180°

by driving said tilt motor under the control of said tilt control portion in a state where said optical pick-up is fixed at an intermediate position in a vertical movement range by moving said optical pick-up to the outer peripheral side of the optical disk, and a reproducing operation is started by moving said optical pick-up to the inner peripheral side of the optical disk;

during the reproducing operation, said tilt control portion does not activate said tilt motor, if the level of the focus error signal is within a certain range, and said tilt control portion activates said tilt motor to control the optical disk to come closer to the optical pick-up in a range where the focus servo is possible, if the level of the focus error signal is beyond the certain range.

2. A tilt control device for an optical disk comprising:

an optical pick-up for reading the information recorded on the optical disk by applying a light beam onto the optical disk,

a tilt mechanism for correcting an inclination of the optical disk, two light receiving sections each of which receives the sub-beam and generates an E-F phase difference therebetween; and

a tilt control portion for controlling said tilt mechanism, wherein

at the initialization, said tilt mechanism is set up at a position where the E-F phase difference is 180°

by activating said tilt mechanism under the control of said tilt control portion in a state where said optical pick-up is fixed, and a reproducing operation is started;

during the reproducing operation, said tilt control portion does not activate said tilt mechanism, if the inclination of the optical disk is within a certain range, and said tilt control portion activates said tilt mechanism to control the optical disk to come closer to the optical pick-up, if the inclination of the optical disk is beyond the certain range.

3. The tilt control device for optical disk according to claim 2, wherein

said optical pick-up is moved to the outer peripheral side of the optical disk at the initialization.

4. The tilt control device for optical disk according to claim 2, wherein

said optical pick-up is fixed at an intermediate position in a vertical movement range at the initialization.

5. A tilt control method for an optical disk comprising the steps of:

at the initialization, moving an optical pick-up to the outer peripheral side of the optical disk;

generating an E-F phase difference between two light receiving sections each of which receiving the sub-beam;

setting up a tilt mechanism at a position where the E-F phase difference is 180°

by driving a tilt motor under the control of a tilt control portion in a state where said optical pick-up is fixed at an intermediate position in a vertical movement range;

starting a reproducing operation by moving said optical pick-up to the inner peripheral side of the optical disk;

during the reproducing operation, not activating said tilt motor by said tilt control portion, if the level of the focus error signal is within a certain range, and activating said tilt motor by said tilt control portion to control the optical disk to come closer to said optical pick-up in a range where the focus servo is possible, if the level of the focus error signal is beyond the certain range.

6. A tilt control method for an optical disk comprising the steps of:

generating an E-F phase difference between two light receiving sections each of which receiving the sub-beam;

at the initialization, setting up a tilt mechanism at a position where the E-F phase difference is 180°

by activating said tilt mechanism under the control of a tilt control portion in a state where an optical pick-up is fixed,

starting a reproducing operation;

during the reproducing operation, not activating said tilt mechanism by said tilt control portion, if the inclination of the optical disk is within a certain range, and activating said tilt mechanism by said tilt control portion to control the optical disk to come closer to the optical pick-up, if the inclination of the optical disk is beyond the certain range.

7. The tilt control device for optical disk according to claim 6, further comprising a step of:

moving said optical pick-up to the outer peripheral side of the optical disk at the initialization.

8. The tilt control device for optical disk according to claim 6, further comprising a step of:

fixing said optical pick-up at an intermediate position in a vertical movement range at the initialization.