Abstract: A laser power control device for use in an optical recording and/or reproducing apparatus that records data on and/or reproduces data from an optical recording medium by driving a laser diode with a laser diode driver.

Abstract: When an external disturbance that causes the corrected amount of light reflected from a glass master disk 15 to surpass a threshold value T1 is applied to the control loop, not only the main control section 38 but also the sub-control section 37 controls the corrected amount 27. In this case, the influence of the external disturbance is suppressed quickly. More specifically, the control voltage of the main control section 38 is held the moment the corrected amount 27 of light reflected surpasses the threshold value T1. The sub-control section 37 controls the corrected amount 27 while the corrected amount 27 remains greater than the threshold value T1, and the sum of the control voltages of the main control section 38 and sub-control section 37 is applied to the piezoelectric element 23, thereby suppressing the influence of the external disturbance.

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 laser diode drive circuit for an optical disc recording and/or reproducing apparatus includes a plurality of laser diodes to output laser beams having different wavelengths, a switch circuit for selectively connecting a required laser diode from a plurality of laser diodes, a laser diode drive power supply circuit for driving the laser diode selectively connected by the switch circuit, a photodiode for detecting at least part of laser beams emitted from the laser diode to convert a detected part of laser beams into an electrical signal, a plurality of current-to-voltage conversion amplifiers connected to an output of the photodiode and whose conversion resistance values can be adjusted and having differently designed center conversion resistance values and an automatic power control circuit connected to outputs of the current-to-voltage conversion amplifiers to output a feedback signal to the laser diode drive power supply circuit.

Abstract: A laser diode unit for an optical pick-up apparatus includes a laser diode for emitting a laser beam; a monitor photodiode for controlling recording optical power; an optical disc on which data is written by the laser beam or from which data is read by the laser beam; and a lens module for reflecting a part of the light beam emitted, in the form of a divergent light beam, from the laser diode, thereby focusing the light beam onto the optical disc, the lens module also serving to transmit the remaining part of the light beam therethrough, thereby allowing the transmitted light beam to be converged by the monitor photodiode. The laser diode unit achieves a slimness of the optical pick-up apparatus while reducing the number of elements required for the laser diode unit and the number of process steps required in the manufacture of the laser diode unit.

Abstract: An apparatus and method for controlling an operation of recording data employed in an optical storage system is disclosed. The apparatus has a sampling-and-holding circuit, an operational amplifier, a plurality of gain amplifiers, and a plurality of switches. The apparatus operates under a short-term open mode, a long-term open mode, and a closed-loop mode sequentially in response to control signals and close/open statuses of the switches. A write-control signal is initialized by using a virtual ground effect within the short-term mode. In the long-term mode, the write-control signal is charged to a voltage level suitable for recording data onto a compact disk, while the charged write-control signal is employed to record data on the compact disk within the closed-loop mode.

Abstract: An optical recording apparatus includes a light source driving unit for driving the light source to emit the light beam; an emission light power detecting unit for detecting an emission light power from the light source; and a light power adjusting unit for controlling the light source driving unit based on a detected light power by the emission light power detecting unit to adjust the emission light power from the light source.

Abstract: This invention comprises additional recording means for recording the data in a predetermined position on an optical disk, then reproducing the data recorded in the predetermined position, and not only detecting the end of the predetermined position but also recording the data again from an unrecorded area following the end and power control means for controlling the recording power in recording the recording data, on the basis of the result of the reproduction in the additional recording.

Abstract: A method of writing data on a disk includes the step of writing a first subset of data on a disk such that an amount of write power to write the first subset of data is adjusted in a closed-loop operation. A write-power signal representing the amount of write power to write the first subset of data is measured. After a write interruption, such as from a buffer under-run, a second subset of the data is written on the disk in an open-loop operation using the measured write power, such that the second subset of data is adjacent to the first subset of data.

Abstract: A multi-level optical recording medium according to the present invention is a multi-level optical recording medium (1) which is capable of recording record data according to multi-level recording that defines light reflection ratios of recording portions (12) into multiple levels by switching the irradiation amount of a recording laser beam between multiple levels, wherein light reflection ratio information enabling identification of a light reflection ratio dynamic range within which respective light reflection ratios of the recording portions (12) should be included is readably recorded.

Abstract: An optical reproduction apparatus in accordance with the present invention has a gain control circuit for controlling a gain of an amplifier circuit which amplifies a reproduction signal in accordance with amplitudes of the reproduction signal from an optical recording medium. The amplitude is sent to a power control calculation circuit which controls the reproduction power of a light beam in accordance with the amplitude. The gain control circuit has a slower response speed than that of the power control circuit at least during a period when the power control circuit controls the reproduction power. This allows to provide an optical reproduction apparatus that can realize the stable reproduction power and automatic gain control even to the unevenness of the amplitudes of the reproduction signal.

Abstract: An optical pickup apparatus comprises a semiconductor laser output controller for emitting laser beam, a photodetector for detecting the emitted laser beam, a sampling processor for performing a sampling process, a pulse current generator for generating erase current pulses, write current pulses, and read current pulses, and a controller for controlling the above components. The apparatus performs the sampling process and generates the current pulses according to a predetermined APC timing and controls the semiconductor laser output controller based on the sampling process and current pulses.

Abstract: The invention relates to a method for initialising a control of a supply voltage of a light source, such as a laser diode, the light source being arranged in a first circuit configuration having an associated first reference voltage level or the light source being arranged in an alternative second circuit configuration having an associated alternative second reference voltage level, the method comprising the steps of gradually changing the supply voltage into the direction of the first reference voltage, measuring a light emission of the light source while gradually changing the supply voltage, if no light emission is measured: starting the control of the supply voltage of the light source after the first reference voltage has been reached and if a light emission is measured gradually changing the supply voltage into the direction of the second reference voltage and starting the control of the supply voltage of the light source after the second reference voltage has been reached.

Abstract: An optical pick-up device includes a semi-conductor laser as a laser light-emitting device, a collimator lens, a directional control mirror, an objective lens, a light amount detecting device, a reflecting mirror that reflects leakage light of the laser light onto the light amount detecting device, and a light amount adjusting member that adjusts the amount of light incident on the light amount detecting device, provided between the light amount detecting device and the reflecting mirror. The light amount adjusting member may include a rotatably or slidably-supported baffle of which a rotational angle or slide position is changed so as to adjust the amount of the light.

Abstract: There is provided a disk device has a controller which determines a linear velocity VL of a disk, a laser output determination circuit which determines a read laser output PR of a photodiode according to this linear velocity and causing the photodiode to emit a laser light on the basis of a control signal C corresponding to the determined read laser output, and a sampling circuit which detects the emitted laser light by a front monitor and makes the control signal of the laser output determination circuit appropriate according to a sampling result obtained by performing the detection several times, wherein, even when a recording processing is performed at high velocity, sampling control of the read laser output can be securely performed.

Abstract: An apparatus and method for driving a laser diode for a recording of data. According to the method, pre-stored variables corresponding to respective manufacturers and respective recording pits of the optical disk are checked. A main pulse based on the checked variables and a sub pulse having a prescribed width are generated. The sub pulse is generated at a prescribed time prior to generating the main pulse. A driving signal for driving a LD to record data is generated upon receiving the main pulse and the sub pulse. Therefore, data recording operations are performed using the driving signal without overpower as in the conventional Mode 1 (e.g., Orange 1), that can take less computation and less time to form recording pits at a desired time/size for a recording period of time as in the conventional Mode 2 (e.g., Orange 2), which can result in improve recording quality.

Abstract: Methods and system are provided for automatic power control of a laser diode, e.g., in a laser driver. In accordance with an embodiment of the present invention, a power controller includes a detector circuit adapted to detect the output of the laser diode and to produce a measured output therefrom. A comparator compares a desired output to the measured output, and produces an error signal therefrom. The error signal is provided to an integrator circuit that produces an integrated error signal. At least one digital-to-analog converter (DAC) uses the integrated error signal to produce a current drive signal that drives the laser diode.

Abstract: An optical recording apparatus includes a light source driving unit for driving the light source to emit the light beam; an emission light power detecting unit for detecting an emission light power from the light source; and a light power adjusting unit for controlling the light source driving unit based on a detected light power by the emission light power detecting unit to adjust the emission light power from the light source.

Abstract: A semiconductor laser drive circuit of the present invention reduces the number of wires, solves the out-of-timing problem of pulses due to differences in wire length, and emit short light pulses at a high transfer rate. A common emitter circuit (18) converts a voltage signal (J1) input at an input port (18a) into a current signal and, when reading information, adds the current signal to a signal output from a high-frequency oscillator circuit (20). High frequency components of the current signal converted from the voltage signal (J1) within a bandwidth of a transistor (Q6) are boosted. Degradation of the output signal of the high-frequency oscillator circuit (20) is kept at a minimum by a common base circuit including the transistor (Q6). A current switch circuit (16) cuts off or lets through the output current of a current mirror circuit (12).

Abstract: The present invention discloses a method for compensating the laser energy of optical disk drives, which is used for adjusting and correcting the light source energy run-out for the laser light source of an optical disk drive, comprising the step of writing in the signal by several different laser illumination parameters when the optical disk drive is under the mode of data write; then using the bottom curve fit to take samples on a plurality of read signals; comparing the data at adjacent points to obtain the data of its relative slope; repeating the previous steps for several times to obtain a complete run-out factor and the maximum optimal laser illumination control parameter; and writing said maximum laser illumination value into the laser illumination control system of the optical disk drive such that the laser light source energy can be optimally compensated and controlled.

Abstract: A method for minimizing spherical aberration in an optical read/write drive caused by variances in lens thickness and laser wavelength. The method provides an economic solution that pairs objective lenses with laser diodes such that the spherical aberration caused by the objective lens is offset by the spherical aberration caused by the laser wavelength, thereby minimizing or completely canceling the overall spherical aberration.

Abstract: A temperature inside the information reproducing and recording apparatus is always monitored and it is judged whether the temperatures is a proper operation start temperature, a stop temperature or a restart temperature or not. Based on this judgement, the start and the like of the reproducing and recording operation is properly controlled. Further, with respect to the reproducing and the recording of the information, their respective proper operation temperature ranges are set individually.

Abstract: A laser diode (LD) driver and method, in an optical recording and reproduction apparatus, drives an LD by receiving channel control signals to control power levels of a laser signal from the LD including switches turning on and off driving potentials, each switch corresponding to the power level of the laser signal according to the channel control signals. A multiplexer multiplexes driving potentials and outputs a multiplexed signal. A gate determines an operating mode of the optical recording and reproduction apparatus according to the channel control signals. A variable gain amplifier variably amplifies a monitor signal according to the operating mode determined by the gate and outputs an amplified monitor signal. A sample and hold circuit samples and holds the amplified monitor signal and outputs a signal indicative thereof. An analog multiplexer outputs a reference signal corresponding to the power level of the laser signal according to the operating mode determined by the gate.

Abstract: A power control circuit for an optical information recording device is disclosed. A power sampling signal from a photodiode is transmitted to a peal envelope acquiring circuit and a bottom envelope acquiring circuit and then sampled and held, which is fed-back to a laser diode driving circuit. The laser diode driving circuit alters a driving signal emitted to the laser diode according to the fed-back signal to adjust the power of the optical signal emitted from the laser diode. Therefore, cost is reduced and the power control circuit is particularly suitable for high-speed recordable optical disk drive.

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 photodetector and optical pickup device which comprises: a monitoring photodetection element (photodiode) 23 for receiving laser beams having different wavelengths from laser light sources; a light source-discriminating photoreceiver 24 represented by a photodiode (240) and a wavelength selection filter (241) for discriminating the wavelength spectra of the laser light sources; and a sensitivity regulation circuit (25) for regulating the sensitivity of the monitoring photodetection element 23 in response to the light source-discriminating photoreceiver 24.

Abstract: An optical device to control the output power of a laser on recording and reproduction without expensive high-speed circuits is provided. The optical disk device of the present invention comprises monitor portion for monitoring the power of laser light, averaged light quantity calculating portion for calculating the averaged light quantity of the power of the laser light, memory portion for memorizing the averaged light quantity, error quantity calculated portion for calculating the difference between the output signals of the averaged light quantity calculating portion and the memory portion, and laser power control portion for controlling the power of the laser light in response to the output signal from the error quantity calculating portion.

Abstract: To implement light quantity monitoring with high frequency responsivity and correction of astigmatic differences of a semiconductor laser with a simple configuration with a fewer parts.

Abstract: An apparatus for recording and/or reproducing information on and/or from a magneto-optical disk including an optical head for projecting a laser beam onto a magneto-optical disk and receiving the laser beam reflected by the disk, an up-down block arranged movably between a lower position and an upper position, an up-down motor for moving said up-down block up and down, a turntable for supporting the disk and a spindle motor secured to said up-down block and having a driving shaft coupled with said turntable for rotating the turntable, a position detecting device for detecting a position of said up-down block to derive a position signal when the up-down block is driven into the upper position, a rotation detecting device for detecting a rotation of said optical information record disk to derive a rotation signal when the optical information record disk is rotated at a predetermined revolving speed, and a control device for initiating a focus control for moving said objective lens and turntable relative to each

Abstract: An apparatus automatically controls the laser power of the light source by the feedback output of the APC detector and prevents the increase of laser power due to an abnormality of the APC detector. The automatic power control unit controls the drive amount of the light source by the detection output of the APC detector, which monitors the emission power of the light source, measures the relationship between the APC drive instruction amount and the detection output of the APC detector, and compares this inclination with the inclination at normal time. Also the automatic power control unit compares the error values before and after APC, and detects the change of the quantity of returned light during a predetermined period. As a result, data destruction due to separation, deviation, contamination or deterioration of the APC detector can be prevented effectively.

Abstract: An optical disc drive according to an embodiment of this invention includes a light-receiving section for receiving light, a conversion section for converting the light received by the light-receiving section into an electrical signal, a generation section for generating a slewing rate control signal, and a signal processing section for processing the electrical signal using the slewing rate control signal.

Abstract: The present invention provides a disk playback device comprising a laser drive circuit 15 for feeding a drive signal to an optical head 4 and adjusting the power of a laser beam irradiated by the optical head 4, an error correcting circuit 11 for detecting an error rate of a reproduced signal, and a system controller 10 for controlling operation of the laser drive circuit for signal reproduction and signal recording based on the output of the error correction circuit 11. The system controller 10 retrieves one limit value of two limit values of a reproduction power wherein the error rate is not beyond a prescribed value, and calculates an optimum reproduction power based on the one limit value retrieved. Accordingly it is possible to move to signal reproduction in a short period of time and to reproduce signals with high accuracy by setting the optimum reproduction power.

Abstract: A method for automatically controlling output power of a pick-up head. When output power of a pick-up head is to be changed, a first switch is utilized to connect a first input port of a comparator circuit to a supply source, and a second switch is utilized to connect a first signal source to a driver circuit such that the driver circuit will control the output power according to a first signal. When voltage drop between the first input port and a output port of the comparator circuit stabilizes, the first switch is utilized to connect the first input port to a sensor, and the second switch is utilized to connect the output port and the driver circuit such that the driver circuit will control the output power according to a comparative signal.

Abstract: In order to compensate for so-called clipping effects, it is proposed, in an apparatus for reading from and/or writing to an optical recording medium in which the light power of a laser diode (1) is to be set to a plurality of light power levels, to perform a calibration to a specific light power level (LP2) before the actual regulation of the light power. On account of the calibration, the instantaneous gradient of the characteristic curve which describes the dependence of the laser light power on the laser diode current can be inferred in order, on the basis of this information, to take account f a change—caused, for example, by ageing r clipping effects—in the characteristic curve gradient in the course of the subsequent regulation of the light power of the scanning beam generated by the laser diode (1).

Abstract: An automatic power calibration apparatus for optical recording devices and a method therefore.

Abstract: A recording condition compensation method for preventing a degradation of recording quality and stably achieving excellent recording quality is provided for an information recording apparatus. This method includes the steps of detecting temperature information in the vicinity of a light source at a predetermined timing, acquiring wavelength information of an optical beam emitted from the light source based on the detected temperature information and pre-acquired wavelength temperature characteristic information of the optical beam emitted from the light source, acquiring wavelength dependency information of a recording condition for an information recording medium, and compensating the recording condition for recording information on the information recording medium based on the wavelength information and the wavelength dependency information of the recording condition.

Abstract: In a pickup device used for a drive apparatus of an optical disc, a storage element is provided. The storage element stores individual characteristic information associated with the pickup device. For example, the storage element stores the individual characteristic information associated with the level of the recording light waveform which is output from the LD provided in the pickup device. In recording information, the microcomputer in the drive apparatus obtains the individual characteristic information from the storage element in the pickup device and executes information recording by using an optimum write strategy determined in consideration of the individual characteristic information. Accordingly, the difference in characteristics of pickup devices is removed, and improvement and stabilization of the recording characteristic can be realized.

Abstract: The invention relates to a method and a device for recording an information signal 10 in a phase change layer of a recording medium. A mark is recorded by a sequence 13 of write pulses and previous marks between the marks to be recorded are erased by a sequence of erase pulses 14. De bias power level 191, 192 between the erase pulses is made dependent on the recording speed, thus obtaining low jitter of the recorded marks and at the same time preventing thermal cross write during erase.

Abstract: When the modulation speed of the laser is increased, it is difficult to correctly detect a peak power and a bias power for controlling a laser power. The bias power current Ib is controlled by the operated value of the operation circuit 3 in accordance with the reproduction power current Ir control value of the servo amplifier 5 at the reproduction just before recording, and as for the erase power Pe, since its period is relatively long, the power is detected by the sample-hold circuit 4 and the erase power current Ie is controlled by the operation circuit 3, and the peak power PP is controlled by the operated value of the operation circuit 3 in accordance with the erase power current Ie, and therefore, a bottom hold circuit and a peak hold circuit are not required and the laser control apparatus which does not require the high-speed performance in a photodiode and a monitor circuit is realized to solve the above mentioned problem.

Abstract: A laser power controller detects the temperature and current setting used for the recording power during initial learning or the previous recording operation. When a new recording operation starts, the controller detects the temperature again and compared the detected temperature with the temperature at initial learning or the previous recording to adjust the current setting used for the previous recording power setting and set the initial recording power current of the new recording operation.

Abstract: An optical pickup to focus a light emitted from a light source using an objective lens, forming a light spot on a recording surface of a recording medium, and performing recording and/or reproducing operations using the light. The optical pickup includes a monitor photodetector and an optical element installed in front of the monitor photodetector to receive and to detect a portion of the light emitted from the light source to control an amount of light power output from the light source and to adjust at least one of an intensity, a beam profile, and a proceeding direction of the light incident on the monitor photodetector.

Abstract: A power control circuit for an optical information recording device is disclosed. A power sampling signal from a photodiode is transmitted to a peal envelope acquiring circuit and a bottom envelope acquiring circuit and then sampled and held, which is fed-back to a laser diode driving circuit. The laser diode driving circuit alters a driving signal emitted to the laser diode according to the fed-back signal to adjust the power of the optical signal emitted from the laser diode. Therefore, cost is reduced and the power control circuit is particularly suitable for high-speed recordable optical disk drive.

Abstract: An optical pickup apparatus is provided with two light sources; an objective lens for focusing light originating from each light source on an optical recording medium; a light separation optical element for transmitting or reflecting the light originating from each light source; a collimator lens for converting the light originating from each light source into a generally parallel beam; an upward-directing mirror for changing the optical path of the light originating from each light source by reflecting it; reflectors disposed between the light separation optical element and the respective light sources, for reflecting parts of light beams emitted from the light sources, respectively; photodetectors for detecting light beams reflected from the reflectors, respectively; and an APC circuit for controlling the power of the light beam emitted from each light source in accordance with a detection output of each photodetector.

Abstract: An optical pickup device has first and second light sources that emit first and second laser beams of different wavelengths, an object lens that concentrates the first and second laser beams on a data recording surface of an optical disk, an optical separator disposed between the first and second light sources and the object lens, and an optical monitor that detects a quantity of light of the second laser beam. The optical separator has a wavelength selecting film that, on one hand, reflects the first laser beam emitted from the first light source toward the object lens and, on the other hand, transmits the second laser beam emitted from the second light source to the object lens, and a reflector that reflects a part of the second laser beam emitted from the second light source toward the optical monitor.

Abstract: A laser driver for driving a semiconductor laser for use in recording information by irradiating light on an information recording medium includes a device, including a PLL circuit, for obtaining (1) information modulated in accordance with a predetermined rule and (2) a clock signal, and outputting a recording current signal corresponding to a modulation signal representing the modulated information through the PLL circuit. The PLL circuit oscillates at a high frequency in synchronism with the clock signal. The laser driver further includes a PLL unlock detection circuit for detecting an oscillating condition of the PLL circuit, and for outputting a detection signal indicative of the oscillating condition of the PLL circuit outside the laser driver as a monitor signal.

Abstract: A laser power control apparatus and method prevent fluctuation in the level of laser power due to a difference between reaction speeds of an automatic power controller according to write speeds of a disc drive. In the apparatus and method, laser power can be automatically controlled to prevent a variation in the level of laser diode driving voltage in read power periods, according to the write speeds of a disc drive, in a write mode. Thus, it is possible to prevent unstable operations of a servo circuit due to a variation of the level of laser power and further, prevent deterioration in the quality of the servo circuit due to a variation in the level of a wobble signal, thereby stabilizing recording characteristics of the disc drive.

Abstract: An optical recording medium allowing data to be recorded on, erased from, and reproduced from, and storing information about power levels of an erase pulse. The recorded erase pattern information may include information about power levels of first and last pulses of an erase pattern for erasing data. The first and last pulses of the erase pattern can be differently set depending on the differing kind of recording layer or layers of a disk or differing kinds of disks and recorded in a reproducible only area or rewritable area of the optical recording medium. Thus, by presetting the appropriate erase power levels, the time required for selecting an optimal erase power for the optical recording medium can be considerably reduced.

Abstract: An optical scanning device for scanning a recordable optical disk (20) with a laser beam having a linear polarisation. A quarter wave plate (16) is used to alter the polarisation of the beam on reflection from the disk. A partially polarising beam splitter (8) is used and arranged such that a proportion of intensity of the incident beam passed is greater than a proportion of intensity of the reflected beam. A relatively high optical signal power at the disk (20) can be achieved for recording purposes whilst allowing the beam splitter (8) to be manufactured in a relatively efficient manner.

Abstract: An optical disk apparatus which records/reproduces data on/from a plurality of types of optical disks. The optical disk apparatus has a plurality of laser diodes. Two laser light rays emanating from two laser diodes are coupled together by means of a coupling prism. The thus-coupled laser light is radiated onto an optical disk. A photodetector is disposed in close proximity to the coupling prism. The coupling prism guides, to the photodetector, a laser light component of at least one laser light ray of the two laser light to be coupled together, the component having not been radiated onto the optical disk on an optical path. Laser light which is not radiated onto the optical disk on the optical path includes diffracted light other than a main beam emanating from the laser diode or laser beam which has not been subjected to coupling at the coupling surface of the coupling prism.

Abstract: In recording on an optical disk, tracking control is performed using tracking error signals detected during an OFF period and a rear time segment within an ON period of a recording pulse signal. The time segment for detecting the tracking error signal within the recording pulse ON period is variably controlled in accordance with recording conditions such as a disk type and recording speed. This control can effectively prevent a tendency of pits being formed off the center line of a track toward the inner circumference of the optical disk due to the influence of residual heat from an adjoining inner track, thereby allowing pits to be formed accurately on and along the track center line.