Abstract: A semiconductor laser driving apparatus for directing light to an optical disc for recording a recording mark based on a recording current and reproducing the recording mark to generate a reproduction signal. The apparatus includes a reproduction current generation section; a high frequency current generation section for generating a current including a high frequency component for reducing semiconductor laser noise in the reproduction; a recording current generation section, the recording current including a pulse corresponding to the recording mark and including a plurality of multi-pulses; and a current driving section for amplification. The apparatus further includes a filter to attenuate the enhanced high frequency components in the high frequency current and in the enhanced high frequency component; and a switching section for switching the filter so that the enhanced component in the recording current is superposed on at least one of the multi-pulses.

Abstract: In an optical disc apparatus, a semiconductor SLD driving device is mounted on an optical pickup in order to realize a high speed switching of drive current for a semiconductor laser diode (SLD), necessary for recording data. The SLD is placed. within 5 cm from the SLD driving device. The driving device becomes a heat source due to driving current of the SLD, and increases a temperature of the optical pickup. Since the temperature rises proportionally to power consumption, power saving is required. A voltage supplied to the driving device is controlled to be a minimum level necessary for keeping the driving device still working on basic functions. The SLD driving device is mounted to the optical pickup, and this driving device handles N pieces of input signals for setting semiconductor laser power and N pieces of switch-timing-input-signals for selecting respective input signals.

Abstract: Address groups are composed of two of address blocks 16, 17, 18, and 19, where the address blocks 16, 17, 18, and 19 are disposed in a sector address region 5 and include identifiable information of address numbers 13 and overlapping sequential numbers 14. The address groups are disposed so that each group is alternately shifted from a track center 2 toward the inner periphery side or the outer periphery side, by a width substantially equal to half the track pitch, along the radius direction.

Abstract: Address groups are composed of two of address blocks 16, 17, 18, and 19, where the address blocks 16, 17, 18, and 19 are disposed in a sector address region 5 and include identifiable information of address numbers 13 and overlapping sequential numbers 14. The address groups are disposed so that each group is alternately shifted from a track center 2 toward the inner periphery side or the outer periphery side, by a width substantially equal to half the track pitch, along the radius direction.

Abstract: According to the present invention, an optical disk recording method for recording data on an optical disk including a land and a groove by forming a mark representing the data on the optical disk by irradiating a light beam onto the optical disk is provided. In this method, conditions for irradiating the light beam are varied depending upon whether a position at which the mark representing the data is formed on the land or on the groove so that a size of the mark formed on the land is equal to a size of the mark formed on the groove.

Abstract: When information is reproduced from an optical disk, a comparator compares a reproduced signal with a slice signal to generate binarized signals, while the slice signal is corrected continuously for external disturbances in a reproduced signal. A switch changes the time constant of the frequency response of the slice signal according to the reproduced signal. For example, the frequency response of the slice signal is set faster in a first region in a prepit area of the disk and in a record area of the disk so that the slice level converges quickly, while the frequency response is changed thereafter to a low time constant for normal signals. Thus, inaccuracy in binarization of the reproduced image signal is minimized, and the sector format is performed efficiently.

Abstract: A method for controlling intensities of a plurality of laser beams respectively emitted on a track of an optical disk by a plurality of laser diodes according to the present invention includes a step of performing focusing servo control for focusing one of the plurality of laser beams emitted by one of the plurality of laser diodes onto the track, and concurrently controlling an intensity of the laser beam emitted by each of plurality of laser diodes to be within a predetermined range by comparing a signal which is in accordance with an intensity of the laser beam emitted by that laser beam with a reference signal. A period during which the one of the plurality of laser diodes used for the focusing does not emit the one laser beam is shorter than a response time of the focus servo control.