Abstract: A servo control apparatus of an optical pickup includes an extractor for extracting an error signal from the read signal; a driver for changing the servo position; an equalizer for equalizing the error signal to generate a drive signal; a calculator for calculating an integral value of the error signal for each predetermined angular section of rotation; a memory for storing each of the integral values for one rotation of the recording medium; a detector to detect an occurrence of a dropout; a calculator for calculating a variation by comparing the integral value for an angular section of rotation where the dropout occurred with a stored integral value for the identical angular section of rotation prior to the occurrence of the dropout; and a controller for changing an equalization characteristics of the equalizer in accordance with the variation.

Abstract: A unit according to the present invention includes a substrate and an IC chip used for driving a light-emitting device. A relay terminal is provided at a region spaced from peripheral areas of the substrate so as to connect the light-emitting device with the IC chip. The relay terminal is connected with a corresponding terminal of the IC chip via a connecting channel such as wire-bonding. The light-emitting device is supported by the substrate such that a terminal of the light-emitting device is electrically connected with the relay terminal. A length of a wiring line between the light-emitting device for an optical pick-up and the unit used for driving the light-emitting device is decreased.

Abstract: An information recording apparatus is provided, which can control over the power of light beams emitted from a light source and various types of servo control with higher accuracy. A laser beam is emitted from a semiconductor laser to write information onto an optical disc. A detection signal indicative of the power of the laser beam output from a light-receiving device is sampled and held with a sample and hold circuit via an I-V converter at a timing delayed by the time corresponding to the delay time of the I-V converter. A tracking error generation circuit and a focus error generation circuit generate a tracking error signal and a focus error signal, respectively, on the basis of a detection signal having information about tracking error and focus error and output from a light-receiving device. Sample and hold circuits sample and hold the tracking error signal and the focus error signal at a timing delayed by the time corresponding to the delay time of each of the generation circuits, respectively.

Abstract: A power controller is provided which can control the emission power from a light source to follow an appropriate response property based on a target value. The power controller includes feedforward systems for allowing currents corresponding to target values set at target value setting units to be switched at a switching device and supplied as a power setting current to an adder. Also included are feedback systems for detecting the power of the laser beam emitted by a semiconductor laser serving as the light source and adjusting a feedback current to stabilize the deviation from the target values at a predetermined value. Further included are a switching device for allowing the target values to be switched and supplied to the aforementioned feedback systems, and the adder for adding a feedback current and the power setting current to thereby generate a drive current for driving the semiconductor laser.

Abstract: An optical disc player having an optical pickup records and retrieves information on an optical disc while the optical disc is rotating. A rotation pulse is generated each time the optical disc rotates through a prescribed angle. A rotation frequency data representing a frequency of the rotation pulse is also generated. A servo processor performs servo processing for rotation control on the optical disc in accordance with the rotation frequency data. A sampling pulse generator performs computational processing on an input data signal to generate a sampling pulse. The sampling pulse generator also corrects the rotation frequency data based on a phase error between the sampling pulse and the rotation pulse to use a corrected rotation frequency data as the input data signal. Another servo processor performs servo processing for repetitive control on the optical pickup using the sampling pulse.

Abstract: In an optical pickup direction detection unit, a detector group receives return light from an optical disc and outputs a light detection electric signal, a push-pull signal generator generates a push-pull signal, and a land prepit signal generator generates a land prepit signal. Further, a direction determiner detects a direction detection signal based on a tracking error signal and the land prepit signal.

Abstract: A focus jump moves a focus position of a light beam in a direction perpendicular to the storage medium to the focus position corresponding to a target recording layer so that the light beam is irradiated on the target recording layer.

Abstract: The present invention provides a multi-layer disk recording/reproducing apparatus that records information on a multi-layer disk having a plurality of recording layers or reproduces the information from the multi-layer disk. The objective lens condenses the light from a light source on the recording layers, and the focus actuator moves the objective lens so that the light forms a focused light spot on the recording layers. The a spherical aberration correcting mechanism is provided on a light path between the light source and the objective lens, and it corrects the spherical aberration generated by the multi-layer disk. The control device starts the movement of the focus actuator after the start of the movement of the spherical aberration correcting mechanism when performing the focus jump operation.

Abstract: A pickup drive apparatus for recording or reproducing with respect to a recording medium such as a CD and a DVD. In the apparatus, return light produced by irradiating an optical spot is detected by a photodetector, and a push-pull signal is produced from this detection output. A tracking error signal is produced from the push-pull signal by a low-pass filter and a phase compensating circuit. A quasi-ON/OFF control signal having information of an irradiation position of the optical spot is produced from the push-pull signal by a high-pass filter, a comparator, and a single pulse generator. When the quasi-ON/OFF control signal is produced which indicates that the optical spot is positioned on a groove, the tracking error signal is outputted via switching circuits in synchronism with this signal production. A pickup is servo-controlled based on this output signal.

Abstract: A recording/reproducing apparatus includes an optical pickup having an objective lens, an actuator for operating the lens, an aberration correction element, and a detector for generating a reading signal; a servo control section; a driver for operating the aberration correction element; a generator for generating a focus disturbance signal and an aberration correction disturbance signal having a period different from that of the focus disturbance signal; and a controller for adjusting the focusing position and the aberration correction amount on the basis of a change in a predetermined characteristic value of the reading signal when the disturbance signals are simultaneously applied.

Abstract: An rotation speed controlling apparatus of an optical recording medium having a wobbled track includes an optical pickup for irradiating a light beam to generate a reading signal according to a wobbling shape of the track; a filter having a predetermined frequency band to pass a wobble reference frequency therethrough for extracting a wobble signal from the reading signal; a generator for generating a wobble reference signal; a detector for detecting the difference between the wobble signal frequency and the wobble reference frequency; a controller for controlling the rotation speed on the basis of the difference between the frequency of the extracted wobble signal and the wobble reference frequency; and a discriminator for discriminating that the wobble signal frequency lies outside the frequency band of the filter; wherein the controller controls the rotation speed in accordance with the detected frequency difference when the wobble signal frequency lies outside the frequency band of the filter.

Abstract: A method of detecting a deviation in a servo control system to control a controlled system, has the processes of: applying a disturbance signal, which has a wave form having a constant frequency, to the controlled system; detecting a variation in a wave form of an output signal output from the controlled system by comparing the wave form of the output signal with the wave form of the disturbance signal; and detecting the deviation on the basis of the detected variation.

Abstract: A track jump apparatus for making an actuator jump in order to move a spot position of a laser beam emitted through an objective lens of the actuator from a current position to an object position corresponding to a desired recording track on a recording medium.

Abstract: An aberration compensation device includes: a phase difference generator for receiving an input signal and for generating a phase difference used for compensating for an aberration induced in a light beam; a temperature detector for detecting a temperature of the phase difference generator; and a corrector for controlling the input signal to be inputted to the phase difference generator based on the temperature detected by the temperature detector thereby to correct a variation of a characteristic of the phase difference generator resulting from a temperature variation.

Abstract: A servo control apparatus for performing a feedback control to a controlled system having characteristics represented by a characteristic equation including at least a second order term, a first order term and a zero order term, includes a disturbance estimating device that has an internal model having characteristics represented by a characteristic equation including only a second order term, and that estimates a disturbance applied to the controlled system by using the internal model, thereby generating an estimated disturbance value; and a compensating device that compensates the disturbance on the basis of the estimated disturbance value.

Abstract: A liquid crystal driving signal generating apparatus comprises a PWM signal generator, a low pass filter for limiting a frequency band of a PWM signal outputted from the PWM signal generator, a liquid crystal panel connected to an output of the low pass filter, and a control means for controlling the PWM signal generator. The control means controls the PWM signal generator such that the PWM signal generator generates a PWM signal with a duty ratio corresponding to a refractive index to be set in the liquid crystal panel.

Abstract: In an optical recording medium having a plurality of recording layers of a double-spiral structure in which information is recorded on both of land tracks and groove tracks, the spiral of a first recording layer (1) is in the forward direction, the spiral of a second recording layer (2) is in the backward direction, first information is recorded on one of the land track (1B) and the groove track (1A) of the first recording layer (1) in the direction from the inner periphery toward the outer periphery of the optical recording medium, and second information subsequent to the first information is recorded on one of the land track (2B) and the groove track (2A) of the second recording layer (2) in the direction from the outer periphery toward the inner periphery of the optical recording medium.

Abstract: A servo control apparatus of an optical pickup includes an extractor for extracting an error signal from the read signal; a driver for changing the servo position; an equalizer for equalizing the error signal to generate a drive signal; a calculator for calculating an integral value of the error signal for each predetermined angular section of rotation; a memory for storing each of the integral values for one rotation of the recording medium; a detector to detect an occurrence of a dropout; a calculator for calculating a variation by comparing the integral value for an angular section of rotation where the dropout occurred with a stored integral value for the identical angular section of rotation prior to the occurrence of the dropout; and a controller for changing an equalization characteristics of the equalizer in accordance with the variation.

Abstract: A servo control apparatus of an optical pickup includes an extractor for extracting an error signal from a read signal; an equalizer including a phase compensator for equalizing the error signal to generate a drive signal; a driver for changing the servo position of the optical pickup in response to the drive signal; a dropout detector for extracting an envelope signal from the read signal to detect a dropout of the read signal; and a controller. The controller changes an equalization characteristics of the equalizer in accordance with an amplitude of the envelope signal during the period of time when the dropout occurs or in response to an occurrence of the dropout.

Abstract: A servo control apparatus is provided to a stable servo control even when delays occur in detecting defects. Based on reflected light of an optical beam from an optical disc, a defect resulting from dark spots, damages, or others on the optical disc is detected. Immediately before the detection, sample data of a control signal are memorized. The sample data are obtained during a predetermined interval of time that corresponds to a detection delay for the defects, which is dependent on a defect detecting device. Using the memorized sample data, a cancel signal is produced for canceling the influence of the control signal, which is owing to a pseudo error signal obtained during the predetermined interval of time. The cancel signal is outputted as the control signal immediately after the detection of the defect.