A method for providing tracking error signals in an optical data storage system includes a step of receiving a wobble signal having a first frequency from the wobble detection system. The wobble detection system includes an optical pick up unit that detects positions of the head relative to lands and grooves. Characteristically, the wobble signal is amplitude modulated for positions intermediate between the land and the groove. The method further includes a step of receiving a primary tracking error signal from the wobble detection system. The wobble signal is multiplied with a synchronous signal to about a product signal. The product signal is positive for a first direction of motion and negative for a second direction of motion that is opposite that of the first direction. The product signal is integrated to obtain a quadrature track error signal.

A method for providing tracking error signals in an optical data storage system includes a step of receiving a wobble signal having a first frequency from the wobble detection system. The wobble detection system includes an optical pick up unit that detects positions of the head relative to lands and grooves. Characteristically, the wobble signal is amplitude modulated for positions intermediate between the land and the groove. The method further includes a step of receiving a primary tracking error signal from the wobble detection system. The wobble signal is multiplied with a synchronous signal to about a product signal. The product signal is positive for a first direction of motion and negative for a second direction of motion that is opposite that of the first direction. The product signal is integrated to obtain a quadrature track error signal.

An information recording and playback device includes a recording and playback unit, and a controller. The controller divides a recording area of an optical disk into a first recording area which is at an inner circumference side, and a second recording area which is at an outer circumference side. The controller controls the recording and playback unit such that the unit records or plays back data in the first recording area at a first speed, and records or plays back data in the second recording area at a second speed slower than the first speed. The predetermined radius is set to a boundary between an area in which a control residual exceeds a predetermined reference value when servo control related to focusing and tracking is performed on the recording area of the optical disk, and an area in which the control residual does not exceed the predetermined reference value.

A method for providing tracking error signals in an optical data storage system includes a step of receiving a wobble signal having a first frequency from the wobble detection system. The wobble detection system includes an optical pick up unit that detects positions of the head relative to lands and grooves. Characteristically, the wobble signal is amplitude modulated for positions intermediate between the land and the groove. The method further includes a step of receiving a primary tracking error signal from the wobble detection system. The wobble signal is multiplied with a synchronous signal to about a product signal. The product signal is positive for a first direction of motion and negative for a second direction of motion that is opposite that of the first direction. The product signal is integrated to obtain a quadrature track error signal.

A method and apparatus for detecting tightness of a pick-up head, and a method and apparatus for controlling the moving of the pick-up head are disclosed. The method for detecting the tightness of the pick-up head includes moving the pick-up head to an inner area of the disc reading device when then disc reading device is powered on, moving the pick-up head to an outer area of the disc reading device within a predetermined time period, moving the pick-up head from the outer area of the disc reading device to the inner area at a constant speed by a first fixed force, and recording the moving duration for moving the pick-up head from the outer area of the disc reading device to the inner area at the constant speed.

An optical disk drive and a digital servo method for the optical disk drive includes controlling functions of the optical disk drive with a microprocessor. Low-pass filtered and gain adjusted versions of individual photodetector output signals resulting from an illumination of an optical disk are received. Versions of the individual photodetector output signals are digitized to produce digital signals. A focus control signal and/or a tracking control signal is determined through at least one servo algorithm executed by a digital signal processor based on a focus error and/or tracking error, respectively, determined from the digital signals. The digital signal processor is an integrated circuit structured and arranged for manipulation of digital signals in accordance with programmed commands, and in a manner that operates faster than the microprocessor.

A method and apparatus for detecting tightness of a pick-up head, and a method and apparatus for controlling the moving of the pick-up head are disclosed. The method for detecting the tightness of the pick-up head includes moving the pick-up head to an inner area of the disc reading device when then disc reading device is powered on, moving the pick-up head to an outer area of the disc reading device within a predetermined time period, moving the pick-up head from the outer area of the disc reading device to the inner area at a constant speed by a first fixed force, and recording the moving duration for moving the pick-up head from the outer area of the disc reading device to the inner area at the constant speed.