Abstract: According to one embodiment, a laser drive circuit which supplies a drive current to a laser element which outputs light at a predetermined wavelength, and a laser control circuit which supplies a predetermined timing pulse for generation of relaxation oscillation in a laser drive current supplied to the laser drive circuit, the laser control circuit supplying a laser drive current higher than a threshold value which is supplied from the laser drive circuit to the laser element to enable laser light to be output from the laser element, the laser control circuit setting the laser drive current to a level lower than the threshold value on the basis of the timing pulse.

Abstract: According to one embodiment, a calibration section controls an LD driving section so as to carry out test writing on a recording layer of an optical disc using a light pulse having relaxation oscillation, irradiates the test-written area with a reproduction laser beam so as to detect reflected light, and determine write strategy based on the detected result. A recording process is executed on the optical disc by using the light pulse having relaxation oscillation based on the write strategy determined by the calibration section.

Abstract: According to one embodiment, an optical disc device includes a light source portion which applies laser light to an optical disc, a drive portion which supplies a drive current to the light source portion so as to cause the light source portion to apply laser light of light pulses having relaxation oscillation, and a controller which controls the drive portion to supply a drive current so as to cause the light source portion to emit laser light of (n?1)×N (N is an integral number) light pulses having relaxation oscillation with respect to a mark with recording mark length nT (n: integral number, T: channel clock) to be recorded on the optical disc.

Abstract: According to one embodiment, an optical recording head device includes a light source which outputs such a relaxation oscillation optical pulse that a full width at half maximum of a single pulse is 820 ps or less, a driving unit for driving the light source, an objective lens which converges emission light from the light source on a recording layer of a recording medium, and captures reflective light which is reflected by the recording layer of the recording medium, a distribution unit, placed between the light source and the objective lens, for distributing incident light, and a photodetection unit for receiving via the distribution unit the reflective light which is reflected by the recording layer of the recording medium, wherein a resonator length of the light source is 6560 ?m or less.

Abstract: According to one embodiment, a first switching element which switches a light source, a second switching element which switches a load element connected in parallel to the light source, and a switch which controls the connection between the first and second switching elements and a constant current source. When the first switching element and the second switching element are differentially operated by the switch, the switch is turned on a predetermined time earlier than the turning on of the first or second switching element.

Abstract: According to one embodiment, to solve a new problem which has been produced due to adoption of a recording method using relaxation oscillation, the laser output control device suppresses unnecessary relaxation oscillation while increasing an averaged light quantity between recording pulses to obtain reflected light quantity which is necessary for tracking and focus controlling. A laser modulation control circuit includes a recording pulse output unit which outputs recording pulses for making relaxation oscillation as the recording pulses, a bias current output unit which outputs a constant bias current between the recording pulses, and a high-frequency overlap unit which overlaps the high-frequency signal on the constant bias current between the recording pulses, and controls so as to have times at which current values at a start edge and an end edge of the high-frequency signal are almost consistent with a value of the constant bias current.

Abstract: According to one embodiment, an apparatus which records a signal in a recording medium in which information is written by using a first laser having a first wavelength and from which information is read by using a second laser having a second wavelength longer than that of the first laser, a signal is recorded in the recording medium by using the first laser, and a control section reproduces the signal recorded with the first laser and measures a first amount that is used to calculate a target value for optimization of recording conditions, reproduces a signal recorded with the second laser and measures a second amount for optimization of a reproduction signal, compares the first amount with the second amount, and determines the first amount under the recording conditions where the second amount becomes optimum as a target value for optimization of the recording conditions.

Abstract: According to one embodiment, an optical head device provides a signal processing circuit which sets a control amount to move an objective lens so that a distance between the objective lens and a given recording layer of the an optical disc coincides with a focal position, an optical path length correction mechanism which corrects an influence of an aberration component producing an error in the focal distance, a thickness difference detection circuit which finds an amount of correction to be made by the optical path length, and an aberration correction circuit which generates a correction signal to correct the influence of the aberration component producing the error in the focal distance detected by the thickness difference detection circuit, and supplies the correction signal to the optical path length correction mechanism.

Abstract: Address information is formed by M wobbles (integer M is the number of wobble waves) per bit as a basic unit, and is NRZ-recorded. Also, a sync signal used in sync detection of the address information is formed by N wobbles per bit as a basic unit (integer N is the number of wobble waves and M=2N). The sync signal with such configuration (6 wobbles per bit) is recorded on the head side of the address information (12 wobbles per bit). In this way, even when external noise is large, a modulated wobble signal can be demodulated more accurately.

Abstract: Address information is formed by M wobbles (integer M is the number of wobble waves) per bit as a basic unit, and is NRZ-recorded. Also, a sync signal used in sync detection of the address information is formed by N wobbles per bit as a basic unit (integer N is the number of wobble waves and M=2N). The sync signal with such configuration (6 wobbles per bit) is recorded on the head side of the address information (12 wobbles per bit). In this way, even when external noise is large, a modulated wobble signal can be demodulated more accurately.

Abstract: Address information is formed by M wobbles (integer M is the number of wobble waves) per bit as a basic unit, and is NRZ-recorded. Also, a sync signal used in sync detection of the address information is formed by N wobbles per bit as a basic unit (integer N is the number of wobble waves and M=2N). The sync signal with such configuration (6 wobbles per bit) is recorded on the head side of the address information (12 wobbles per bit). In this way, even when external noise is large, a modulated wobble signal can be demodulated more accurately.

Abstract: Disclosed is an optical disk device including: an objective lens unit having an objective lens and a lens holder; an elastic supporting member supporting displaceably the objective lens unit on a body of an optical head; first and second drive sections applying respectively driving forces to first and second driven positions on the objective lens unit opposed across a position of a center of mass of the objective lens unit in a direction orthogonal to an optical axis of the objective lens; and a driving force adjustment section adjusting allocation of the driving forces respectively applied to the first and second driven positions so that a possible influence of a displacement force in a tilt direction on a displacement force in a focusing direction at the position of the center of mass when the displacement forces act on the objective lens unit is avoided.

Abstract: According to one embodiment, in a data write operation, the average value of the emission power detected by a front monitor is obtained via a low-pass filter and a sample hold circuit. In the write operation, erase power controlled by an erase APC is obtained via a sample hold circuit. While an LD is emitting light with the erase power, an erase current is determined from the output voltage of the erase APC. On the basis of the average power, the erase power, the erase current, and a waveform of the recording pulse, a current-to-emission-power characteristic of the LD is estimated. Furthermore, on the basis of the current-to-emission-power characteristic, the peak power in the write operation of the LD are controlled.

Abstract: In a laser-power control method, a power of laser light emitted from a laser-light emitting element and a driving current for driving the laser-light emitting element are detected. An approximate expression indicating a driving-current to light-power characteristic of the laser-light emitting element is updated on the basis of the detected light power and the detected driving current while sequentially increasing accuracy. A command driving current corresponding to a target light power is calculated by using the updated approximate expression. The laser-light emitting element is driven on the basis of the calculated command driving current so as to output the target light power.

Abstract: An optical disc apparatus includes a laser-light emitting element configured to emit laser light onto a writable and readable optical disc, a power detecting unit configured to detect a light power of the laser light emitted from the laser-light emitting element, and a power control unit configured to control a driving amount for the laser-light emitting element by feedback control so that the detected light power coincides with a target light power. The power control unit holds a driving amount obtained during a previous recording period until a current recording period, and uses the held driving amount as an initial driving amount for the feedback control in the current recording period when the current recording period starts.

Abstract: To improve a recording speed and an optical waveform quality while lower power consumption in the laser driver circuit is achieved. In an optical disc apparatus including a laser driver circuit according to the present invention, a laser diode emits a laser light a power supply regulator supplies a predetermined power supply voltage to the laser driver circuit, a control micro computer performs a control to switch the predetermined power supply voltage supplied from the power supply regulator to the laser driver circuit in accordance with a recording time or a reproduction time.

Abstract: In order to compute a set value for a laser driver circuit for obtaining laser light having a predetermined irradiation power by using a calibration coefficient indicating manufacturing errors. In an optical disc device including a laser driver circuit according to the present invention, a laser diode emits laser light, a front monitor photo diode receives the emitted laser light to generate a reception light signal, an APC unit of the laser driver circuit compares the thus generated reception light signal with a target value related to the predetermined irradiation power previously set in the laser light to be emitted, a drive of the laser diode is controlled to match the signal to the target value, and a CPU uses at least one calibration coefficient to compute the set value for matching the reception light signal to the target value.

Abstract: Address information is formed by M wobbles (integer M is the number of wobble waves) per bit as a basic unit, and is NRZ-recorded. Also, a sync signal used in sync detection of the address information is formed by N wobbles per bit as a basic unit (integer N is the number of wobble waves and M=2N). The sync signal with such configuration (6 wobbles per bit) is recorded on the head side of the address information (12 wobbles per bit). In this way, even when external noise is large, a modulated wobble signal can be demodulated more accurately.

Abstract: This invention relates to a focus control apparatus having a controller which generates a control signal and performs focus operation when the peak timing of a focus sum signal based on reflected light and the zero-crossing timing of a focus error signal are detected to substantially coincide with each other in supplying a control signal to a lens actuator driver for supplying a driving signal to a lens actuator for driving a lens. The invention also relates to an optical disk apparatus using the focus control apparatus. By detecting coincidence of the two timings, two reflected waves are discriminated, and stable focus operation is achieved.

Abstract: Address information is formed by M wobbles (integer M is the number of wobble waves) per bit as a basic unit, and is NRZ-recorded. Also, a sync signal used in sync detection of the address information is formed by N wobbles per bit as a basic unit (integer N is the number of wobble waves and M=2N). The sync signal with such configuration (6 wobbles per bit) is recorded on the head side of the address information (12 wobbles per bit). In this way, even when external noise is large, a modulated wobble signal can be demodulated more accurately.