Patent ID: 7190645
Filing Date: 2007-03-13
Classification: G11B

Abstract:
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.