Abstract: An apparatus and method for slicing an RF signal and compensating for the slice level of an RF signal reproduced from a disk, which minimizes a block error rate by optimizing the slice level of the RF signal according to variations in symmetry of the RF signal when slicing the RF signal. A comparator converts the RF signal reproduced from the disk into a digital signal by comparing the RF signal with a slice level, a low-pass filter low-pass filters the digital signal and provides the result to the comparator as the slice level, and a slice level compensator compensates for the slice level provided to the comparator by the low-pass filter according to variations in symmetry of the RF signal.

Abstract: An optical pickup apparatus includes a first light source to emit a first light beam having a predetermined wavelength, a first optical path changer to change a proceeding path of the first light beam, an objective lens to focus the first light beam on a recording medium, a diffraction member to divide the first light beam reflected by the recording medium into five light regions, the diffraction member having a first diffraction region having a wide width in a direction corresponding to a tangential direction of the recording medium and second through fifth diffraction regions sequentially arranged around the outside of the first diffraction region in a direction corresponding to a radial direction of the recording medium, and a first photodetector having first through fifth light receiving portions to receive the first light beam reflected by the recording medium.

Abstract: An automatic power control (APC) apparatus reducing time necessary for stabilizing an APC circuit at the initial stage of automatic power control of a disc drive is provided. The APC circuit is designed such that a voltage of a predetermined percent of an expected output voltage is previously added to an APC output voltage of the APC circuit of a laser diode, thereby greatly reducing a stabilizing time necessary for stabilizing an APC output voltage at an initial stage in a write or read mode . Therefore, the loss of data in a high speed write or read mode can be reduced. Particularly, the loss of data in a high speed write mode can be greatly reduced.

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: An optical recording/reproducing apparatus which controls the power of a laser diode (LD) and a method therefor. A current power level of an optical signal output by the LD is compared with a reference level and the output of the LD is controlled according to the comparison result. A photo detector (PD) monitors the current power level of the optical signal output by the LD. The current power level is compared with a reference level and power to the LD is controlled based on the comparison. Two different control loops are provided. In a first loop, comparison data is continually provided and in a second loop, sampled comparison data is provided based on a non return to zero inverted (NRZI) signal. Rapid change in an optical output is controlled using the different loops according to a kind and state of a medium such as a disc.

Abstract: A servo controlling apparatus of an optical disk drive and a control method thereof are provided for achieving precise control by automatically controlling the gain of error signals caused by the difference in the amount of light irradiated during recording and reproducing, and then using the automatically gain-controlled signal. In a first control step, a focus error signal and a tracking error signal generated from a photodetecting portion via an operator are multiplied by a predetermined value in different multipliers, and then each obtained value is divided by an RF sum signal to control the value of error to within a predetermined target value. In a second control step, each multiplied focus error signal and tracking error signal are divided by a DC signal corresponding to the average level of the RF sum signal when the error value reaches the target value.