Patent ID: 6157601
Filing Date: 2000-12-05
Classification: G11B

Abstract:
An apparatus for auto adjustment of the gain of a focusing/tracking servo control loop for the optical pickup of an optical disc drive, the optical pickup being coupled to a plant for focusing/tracking control and generating a focusing/tracking error signal when performing a read operation, said apparatus comprising:switching means connected to receive the focusing/tracking error signal from the optical pickup, capable of routing the focusing/tracking error signal to a first path when the optical disc drive is operating in a tuning mode and to a second path when the optical disc drive is operating in a normal mode;a relay circuit coupled to the first path to receive the focusing/tracking error signal from said switching means when operating in the tuning mode, said relay circuit generating a self-sustained oscillating signal in response to the received focusing/tracking error signal;a comparison circuit coupled to the first path to receive the focusing/tracking error signal from said switching means when operating in the tuning mode, capable of generating a gain control signal in proportion to the difference between the focusing/tracking error signal and a preset reference;control means coupled to receive the output of said relay circuit when operating in the tuning mode and coupled to receive the focusing/tracking error signal from said switching means when operating in the normal mode, said control means being capable of compensating for the gain and phase of the received signal; anda gain adjusting unit coupled to said control means to receive the compensated focusing/tracking error signal from said control means and having a variable gain adjustable by the gain control signal from said comparison circuit, the gain being sent to the plant of the optical pickup to cause the plant to produce and transfer a corresponding driving signal to the optical pickup so as to control the focusing and tracking operation of the optical pickup.