Abstract: A method of discriminating an optical disc type and an apparatus thereof. The method for an optical disc system of recording and/or reproducing an optical disc that includes an optical pickup having a laser diode, an object lens, and a light receiving device, checks a track error signal while moving the object lens to upward/downward, and discriminates an optical disc type by using the magnitude of the checked track error signal. The method and apparatus discriminate the disc type in the initial stage of focusing where the object lens moves to upward/downward.

Abstract: A method and apparatus for correcting a tilt without repeatedly calculating a tilt angle with respect to a corresponding recording or reproducing sector, by managing the tilt angle detected with respect to each recording sector of a disc in a disc drive. If a tilt of a disc mounted in the disc drive is detected, a memory is searched for a tilt angle for a sector of the disc in which the tilt is detected. If no tilt angle is found in the memory, a tilt angle is calculated for the sector based on the detected tilt of the disc, the tilt of the disc is corrected, and the calculated tilt angle is stored in the memory to be used for the sector. If a tilt angle is found in the memory, the tilt of the sector is corrected using the found tilt angle.

Abstract: A method of determining a type of a disc for a disc system to record/reproduce a plurality of recordable discs having different track pitches, including detecting a plurality of signals for determination while moving an objective lens up or down and simultaneously making the objective lens vibrate in a radial direction of the disc, and determining the types of the discs having different track pitches by using the detected signals for determination.

Abstract: A plurality of types of writable discs on which wobbles having a predetermined frequency containing absolute addresses and/or various pieces of information on the writable discs can be discriminated by controlling only focusing and using an amplitude of a wobble signal or a wobble PLL lock signal that has passed through a phase locked loop. Accordingly, a discrimination time can be reduced and a disc in an unrecorded state can also be discriminated.

Abstract: A disturbance compensation module using learning control generates a control input to compensate for track position errors due to a periodic disturbance occurring in an optical recording medium in an optical recording medium drive servo system of an optical recording/reproducing apparatus. The module includes a first filter to filter the track position errors and a memory to store control inputs to compensate for a track control cycle in a corresponding address. A second filter filters the control inputs stored in the memory. An adder adds the filtered track position errors from the first filter to the filtered control inputs from the second filter and outputs a result to the memory, updating the control inputs to compensate for the track position errors.

Abstract: A method, apparatus, and computer readable medium controlling a servo of a recording and/or reproducing apparatus, using a detected header field signal. An optical recording and/or reproducing apparatus includes a playback signal detector that detects a playback signal and a track error signal from information recorded on a DVD-RAM disc, as picked up by a pickup. A header field signal detecting circuit detects a header field signal by comparing a sampled playback signal for a signal representing the presence of a header field with a reference level and holding the comparison result for a predetermined period of time to generate the header field signal. Accordingly, a tracking servo can be stably controlled by using a tracking driving signal that is not affected by the presence of a header. Also, in a seek mode, the track error signal can be held based on the header field signal to generate a track count signal that is similarly not affected by the header.

Abstract: A method and apparatus preventing a disc from being scratched by an objective lens. A focus pull-in operation is performed. If a level of a pull-in signal remains lower than a predetermined critical level for a predetermined critical period of time or more, the objective lens is controlled so as to move away from the disc.

Abstract: A tilt adjusting method and apparatus use jitter feedback. The tilt adjusting apparatus includes a jitter detection unit, which detects the jitter quantity of a reproduction signal picked up by a pickup unit, a jitter data preprocessing unit, which filters the jitter quantity in a predetermined window interval unit and obtains a value of an objective function from the filtered jitter data in each predetermined time unit, and a tilt control unit, which obtains a tilt adjusting value by performing tilt control using the value of the objective function and feeds the obtained tilt adjusting value back to a tilt driving unit. According to the tilt-adjusting method and apparatus, when data on an optical disc with a tilt defect is reproduced, quantified jitter values being fed back are adjusted.

Abstract: A disc drive to control a home-in mode and method thereof includes a pickup unit irradiating a light beam on a disc loaded in the disc drive, a motor moving the pickup unit along a radius direction of the disc, and a control unit detecting and storing position information of the pickup unit based on driving pulses of the motor. The control unit controls a generation of the driving pulses of the motor using information of a home-in position based on the stored position information of the pickup unit and the driving pulses of the motor.

Abstract: An apparatus to control a step motor in an optical disk driving system to move a sled which transfers a pickup unit, including a playing unit, a coarse search unit, and a driving unit. The playing unit generates a first step pulse at a first interval of time set by a disk speed according to a comparison between a sled control signal and a tracking driving signal in a playing mode with a predetermined threshold. The coarse search unit generates a second step pulse at a second interval of time stored in a table according to a number of motion steps and a motion direction corresponding to an amount of motion of the pickup unit due to operations in a search mode. The driving unit drives the step motor based on the first and second step pulses.

Abstract: A tilt compensating device and method of performing normal tilt compensation in the event of a servo emergency which may occur during reproduction of data from an optical recording medium are provided. The tilt compensating device includes: an optical pickup; a tilt adjusting unit that adjusts a tilt angle of the optical pickup; a jitter detecting unit that detects an amount of jitter in a reproduction signal output from the optical pickup; and a controlling unit that monitors speed at which the optical recording medium operates using a phase-locked loop (PLL) signal generated from the reproduction signal and the degree of focus of the optical pickup, performs an operation to return to a normal state if any abnormality occurs, and controls operation of the tilt adjusting unit by comparing an amount of jitter detected at regular intervals against a reference.

Abstract: A method for compensating for tilt in reproducing an optical reproducing medium is performed by determining an initial tilt driving direction so as to not interrupt a reproducer when tilt compensation is performed on the optical recording medium. The tilt compensation method involves comparing the amount of jitter detected over a certain period of time when the optical recording medium is reproduced with a reference value; determining the direction of tilt compensation in the direction of reproducing a track of the optical recording medium, before performing tilt compensation, when the amount of jitter detected, according to a comparison result of the comparator, exceeds a reference value; and resuming reproduction of the optical recording medium after performing tilt compensation so that the jitter decreases in the direction of the determined tilt compensation.

Abstract: An apparatus and a method of playing an optical recording medium, including a method of compensating for a tilt by a real time tilt detection before and during a playing operation of the optical recording medium. A tilt compensating apparatus includes an optical pickup, a tilt adjuster which adjust a tilt of the optical pickup, a jitter detector which detects a jittering amount of a playing signal generated from the optical pickup, and a tilt controller which controls operations of the tilt adjuster so as to have the jittering amount become minimum by comparing the jittering amount detected before a reproduction of a content of the optical recording medium with a first jittering reference value, and comparing the jittering amount detected during the reproducing of the optical recording medium, per a certain period, with a second reference value. Since the reproduction of the optical recording medium is performed after a tilt compensation, it takes a shorter time to start the reproduction operation.

Abstract: A disk drive servo system for eccentricity compensation and a method thereof includes an error detector detecting a position error between an actual position and a predetermined nominal reference position of a turntable actuator, a feedback unit generating and outputting a first control value to compensate for the position error received from the error detector, a learning controller calculating, storing, and outputting a second control value to compensate for eccentricity at one or more predetermined speeds of the disk drive, and a gain/phase adjustor providing gain and phase compensation information corresponding to the second control value of the learning controller according to frequency response characteristics of the turntable actuator at the one or more predetermined speeds.

Abstract: An eccentricity compensating apparatus of a disk drive servo system using frequency response characteristics of an actuator actuating a head to a position on a disk to read data on or reproduce data from the disk. The apparatus includes an error detector that detects a position error between a reference head position and an actual position of the head on the disk and a first compensation controller that receives the position error from the error detector and changes the actual position of the head to compensate for the position error.

Abstract: A differential phase detection device receives first through fourth detection signals from a photodetector and detects a differential phase signal therefrom, the differential phase detection device includes a slicer slicing and digitizing each of the detection signals with respect to a reference level. A synthesizer synthesizes the digitized detection signals and generates therefrom synthesis signals. A phase difference detector compares phases of the synthesis signals and outputs a first phase difference signal and a second phase difference signal. A matrix circuit processes the first and second phase difference signals to output the differential phase signal.

Abstract: A DVD-RAM disk reproduction apparatus for reducing an error during detection of ID data, which includes a first operational amplifier for obtaining a sum signal resulting from the addition of four picked-up signals picked up by divided-by-four photodiodes from a DVD-RAM disk having a header region and a recording region, second and third operational amplifiers for respectively obtaining two sum signals corresponding to the upper and lower regions of the header region resulting from the addition of the first and second picked-up signals and the third and fourth picked-up signals, respectively, a fourth operational amplifier for obtaining a difference signal between the two sum signals, a header region detector for detecting upper and lower header region signals corresponding to the upper header region and the lower header region based on the difference signal, and detecting a header region signal corresponding to a header region by logically summing the two detected signals, a first multiplexer for selecting o

Abstract: A disturbance compensation module using learning control generates a control input to compensate for track position errors due to a periodic disturbance occurring in an optical recording medium in an optical recording medium drive servo system of an optical recording/reproducing apparatus. The module includes a first filter to filter the track position errors and a memory to store control inputs to compensate for a track control cycle in a corresponding address. A second filter filters the control inputs stored in the memory. An adder adds the filtered track position errors from the first filter to the filtered control inputs from the second filter and outputs a result to the memory, updating the control inputs to compensate for the track position errors.

Abstract: A focusing control apparatus for use in an optical disk system includes a focusing error detector for detecting the focusing error signal from the focusing information of a light beam irradiated onto and reflected by an optical disk, a system state gain controller for detecting the state of the system from an error signal detected from the focusing error detector, so as to automatically control the gain of the system according to the change in system gain, a phase compensator circuit for compensating phase of focuing error signal according to the focusing error signal whose gain is controlled by the system state gain control means, and an actuator driving circuit for driving the actuator according to the compensated signal, so as to maintain system stability.