Abstract: A steering device includes: an offset correction value storing section to store an offset correction value including a first offset correction value and a second offset correction value, the first offset value being a current value for correcting the first sensed current signal so that a value of a vibration of the electric motor is equal to or smaller than a first predetermined value when the motor rotation speed signal is a first rotation speed, and the second offset value being a current value for correcting the first sensed current signal so that the value of the vibration of the electric motor is equal to or smaller than a second predetermined value when the motor rotation speed signal is a second rotation speed.

Abstract: A circuit includes a capacitance coupled between a high voltage node and ground, a laser diode having an anode coupled to the high voltage node and a cathode coupled to an output node, and a current source coupled between the output node and ground. The current source turns on based on assertion of a trigger signal and sinks current from the capacitance to ground to thereby cause the laser diode to lase, and turns off based on deassertion of the trigger signal. A clamping circuit is coupled between the output node and the high voltage node, and clamps voltage at the output node occurring when the current source switches off.

Abstract: A semiconductor light emitting element has a laminated structure formed by laminating a first compound semiconductor layer, an active layer, and a second compound semiconductor layer. The semiconductor light emitting element satisfies ?I2>?I1, where ?I1 is an operating current range when the temperature of the active layer is T1, and ?I2 is the operating current range when the temperature of the active layer is T2 (where T2>T1). The semiconductor light emitting element satisfies P2>P1, where P1 is a maximum optical output emitted when the temperature of the active layer is T1, and P2 is the maximum optical output emitted when the temperature of the active layer is T2 (where T2>T1).

Abstract: An apparatus and method provide for performing, using a heat-assisted magnetic recording head, multiple sequential writes to a recording medium, and recording a metric of write performance for each of the writes. The apparatus and method further provide for calculating fluctuations in the metric, detecting whether the head has a laser mode hopping problem using the metric fluctuations, and categorizing a severity of the laser mode hopping problem.

Abstract: An apparatus of the present disclosure includes a controller coupled to a read/write head wherein the controller is configured to perform various operations. More specifically, the controller is configured to monitor an operational parameter of the read/write head and to detect a fault based on the operational parameter. The fault indicates that a write enabling energy source is malfunctioning during a write operation. The controller is additionally configured, in response to the fault, to take remedial action to protect data associated with the write operation.

Abstract: The present invention relates to a plasmon generator, in which a surface plasmon is excited by application of light. The plasmon generator extends along one direction. The plasmon generator includes a first end surface that is positioned on one end in the one direction and at which near-field light is generated along with the excitation of the plasmon; and a second cross section that is substantially parallel to the first end surface and is away from the first end surface. The first end surface has a polygonal shape that does not have a substantially acute inner angle. The second cross section has an upper part that has a shape substantially the same as or similar to that of the first end surface and a flare shaped lower part that is connected to the upper part and has a width that increases as it is far from the upper part.

Abstract: An optical disc device uses an optical disc (6) capable of super-resolution reproduction, and includes a semiconductor laser (1), a laser driving circuit (21) that supplies a driving current to the semiconductor laser, a light receiving element (8) that detects return light from the optical disc (6) and obtains reproduction signal of recording data of the optical disc (6), and a light emission amount control means (22) that controls a light emission amount of the semiconductor laser (1) by the laser driving circuit (21) so as to keep a peak intensity of a focused light spot formed on an information recording layer of the optical disc 6 to be greater than or equal to a peak intensity at which a super-resolution effect is obtained.

Abstract: An apparatus includes a slider body, a write element, and a laser chip. The write element is disposed on the slider body and is configured to apply a magnetic field to write data on a portion of a heat-assisted magnetic recording media in response to an energizing current. The laser chip has a laser diode with an active region configured to produce light. The laser diode adapted to inject the light to the proximate the read/write element. The laser chip additionally has a photodetector The photodetector is adapted to monitor light from the laser diode. The photodetector shares a same active region as the laser diode and the laser diode and photodetector are integrated together on the same laser chip.

Abstract: The present invention optimizes recording power based on correct ? value. Whether an average of modulation values between the 2-4th AUNs is equal to or less than 65% of an average of modulation values between the 5-7th AUNs or not is judged. Otherwise, the gradual emission is performed, the ? value is measured, and then the following requirement is judged: (average of ? values between 5-7th AUNs)?(average of ? values between 2-4th AUNs)?0.18 If each requirement is satisfied, track shift is judged to occur. The recording area of high output is compared with the recording area of lower output to judge whether or not magnitude relation matches the correct magnitude relation. Also, whether the difference between the ? value of high output and the ? value of lower output is equal to or more than the predetermined value (0.18) or not is judged.

Abstract: Embodiments of optical disc drives are described that perform automatic forward sense calibration of write laser power using a sample and hold sampling strategy that is automatically determined based on an automatically selected write strategy. Embodiments of the described optical disc drive may be dynamically configured to support any optical disc media, any write mode, and any write strategy. The write strategies supported may include dynamically changing write speeds and/or write power levels across the respective optical media tracks. As the optical drive is automatically configured for a selected write media/write mode/write strategy, the sample and hold sampling delays used to control the sampling of a forward sense feedback signal are also automatically configured, thereby allowing each forward sense sampling point to be aligned with an area of the forward sense feedback signal that corresponds to a power level of interest and that avoids distortion in the feedback signal.

Abstract: A thermally-assisted magnetic recording (HAMR) disk drive uses a thermal sensor to accurately monitor laser power during writing. The disk drive controller, or a separate processor, computes a prediction of the laser power from a history of laser power settings. This predicted value is compared with the measured value from the thermal sensor. If the difference is too large or too small, indicating that the laser power is too high or too low, an error signal is sent to the disk drive controller. The disk drive controller may adjust the laser power setting and initiate a re-write of the data. The predicted laser power is calculated from a convolution of a sequence of current and prior laser power settings with a sequence of coefficients. A calibration process generates the sequence of coefficients when the disk drive is idle or just after it is powered on.

Abstract: A heat-assisted magnetic recording system may include, but is not limited to: at least one magnetic recording read/write head; at least one laser diode configured to illuminate at least a portion of at least one magnetic recording medium; at least one laser power level sensor configured to detect a power level of the at least one laser diode; and a controller configured to modify one or more power level settings associated with the at least one laser diode in response to one or more output signals of the at least one laser power level sensor.

Abstract: In an optical recording method, recording parameters (WU) to be used for recording are obtained using recommended recording parameter values (WR) read from an optical recording medium and previously obtained vector information (PC) and approximation coefficients (Ca, Cb) (S24). Writing to the optical recording medium is performed using the obtained recording parameters (S17). The vector information (PC) includes a vector component of the parameters obtained statistically with respect to parameter difference values (DF) between optimal recording parameter values (WO) and the recommended recording parameter values (WR) over a plurality of optical recording media so as to strengthen mutual correlation between the parameters.

Abstract: A method, system and apparatus for fault protection using a linear feedback shift register are presented. The system comprises a protected register containing a first portion for holding a value for a sequence of numbers and a second portion for other parameters. The system also comprises a linear feedback shift register circuit configured to write the sequence of numbers to the first portion of the protected register. If the written sequence of numbers of the protected register matches a reference sequence of numbers, a rewrite circuit is configured to write the second portion of the protected register.

Abstract: An optical disc apparatus includes: a light source; a power detection portion that detects optical power of light emitted from the light source; a temperature detection portion that detects an ambient temperature of the power detection portion; a storage portion in which information relating to a temperature drift characteristic of the power detection portion is stored; and a control portion that controls the optical power while performing a temperature correction relating to the power detection portion by using the information stored in the storage portion. In the optical disc apparatus, the information stored in the storage portion is updated.

Abstract: Provided are a method of optical writing on a disc and a device adopting the method. The method of optical writing includes initially driving a laser diode (LD) at a preset reference value corresponding to a target output, detecting an actual output power by monitoring light output by the LD, and comparing the actual output power to the target output power. The method further includes compensating the reference value and writing data to the optical disc using the compensated reference value.

Abstract: Provided is an optical write device and method. The optical recording method includes generating a first signal including a preset write pulse power Pm in response to information to be written, generating a second signal including an over drive pulse power Po that is synchronized with the preset write pulse power Pm and which is at a higher level than the preset write pulse power Pm, and writing the information to an optical disc using a driving signal that is obtained by synthesizing the first and second signals.

Abstract: A reproducing device includes: a laser light irradiating section; a correction coefficient information retaining section; a correction coefficient obtaining section; a laser power setting section; and a driving signal outputting section.

Abstract: An information recording device in accordance with the present invention obtains drive information of a semiconductor laser which is included in a magnetic head by means of a drive information obtaining section and successively records the information in a drive information storing section. A magnetic head control section controls the magnetic head in accordance with a condition of the semiconductor laser on the basis of the drive information thus obtained by the drive information obtaining section.

Abstract: Disclosed is an improved DRAW technique for writing data on an optical storage medium and reading the data in parallel. In obtaining the optical power of a first light source 1, writing user data is temporarily suspended to write non-user data with a second light source 2 turned OFF.

Abstract: A method, system and apparatus for fault protection using a linear feedback shift register are presented. The system comprises a protected register containing a first portion for holding a value for a sequence of numbers and a second portion for other parameters. The system also comprises a linear feedback shift register circuit configured to write the sequence of numbers to the first portion of the protected register. If the written sequence of numbers of the protected register matches a reference sequence of numbers, a rewrite circuit is configured to write the second portion of the protected register.

Abstract: In write power adjustment for an optical disc having a plurality of information storage layers, data of trial writing is varied by the influence of layers other than a target layer. It is difficult, therefore, to determine optimal write power. A modulation M[m] is obtained from a reproduction signal amplitude of a signal subjected to the trial writing performed with use of write powers Pw[m] (m being an integer) of a plurality of kinds. At least an optimum write power intercept Pint_opt is determined by fitting a relation between the Pw[m] and the M[m] by a modulation characteristic formula M=Masy×(1?(Pint?Pasy)/(Pw?Pasy)) having an asymptotic modulation Masy, a write power intercept Pint, and an asymptotic write power Pasy as parameters. Approximation accuracy by the fitting and/or quality of the trial writing signal are evaluated with use of at least the M[m], the modulation characteristic formula, and the Pint_opt.

Abstract: Erroneous data erasure owing to radiation of laser beam with excessive power to the recording layer of the multilayered optical disc upon servo-off while reproducing data of the disc is prevented. When detecting the servo-off based on the amplitude of the tracking error signal or the focus error signal, the laser beam power is reduced to a predetermined minimum value, and the laser beam power value is set again based on the address of the recording medium, which has been obtained later for reproduction. The laser beam power value is changed by applying an offset to the drive current or changing the target value under APC.

Abstract: The wavelength is monitored using a spectrum analyzer in a state where a semiconductor laser is being driven while changing the light-emitting time of the semiconductor laser. When the internal temperature of the semiconductor laser estimated from a measured wavelength falls out of a preset temperature range, a gimbal assembly is identified as a defective product.

Abstract: An optical information record/playback device of the present invention includes: a light source; a current driver for supplying current to the light source; an optical system for condensing light from the light source onto a recording medium; a monitoring section for monitoring light emission power of the light source; a current driver control section for controlling output current of the current driver; and an arithmetic/control section for controlling an operation of the current driver control section. Before recording information, the arithmetic/control section sequentially conducts a first test light-emission to cause the light source to emit light by using a closed loop circuit and a second test light-emission to cause the light source to emit light by using an open loop circuit, and compares first and second sampling values, which are respectively obtained by sampling the outputs of the monitoring section during the first and second test light-emissions.

Abstract: A semiconductor light emitting device downsized by devising arrangement of connection pads is provided. A second light emitting device is layered on a first light emitting device. The second light emitting device has a stripe-shaped semiconductor layer formed on a second substrate on the side facing to a first substrate, a stripe-shaped p-side electrode supplying a current to the semiconductor layer, stripe-shaped opposed electrodes that are respectively arranged oppositely to respective p-side electrodes of the first light emitting device and electrically connected to the p-side electrodes of the first light emitting device, connection pads respectively and electrically connected to the respective opposed electrodes, and a connection pad electrically connected to the p-side electrode. The connection pads are arranged in parallel with the opposed electrodes.

Abstract: Provided are a method of optical writing on a disc and a device adopting the method. The method of optical writing includes initially driving a laser diode (LD) at a preset reference value corresponding to a target output, detecting an actual output power by monitoring light output by the LD, and comparing the actual output power to the target output power. The method further includes compensating the reference value and writing data to the optical disc using the compensated reference value.

Abstract: An optical-pickup apparatus includes: a first laser-light source to emit a first laser beam to a first optical disc; a first photodetector to output a first monitor signal indicative of intensity of the first laser beam; a second laser-light source to emit a second laser beam to a second optical disc; a second photodetector to output a second monitor signal indicative of intensity of the second laser beam; a signal-selection unit to select the first monitor signal when recording or reading of information is performed for the first optical disc, and select the second monitor signal when recording or reading of information is performed for the second optical disc; and a signal-transmission unit to transmit, via a common transmission path, the first monitor signal or the second monitor signal selected by the single-selection unit to a control circuit configured to control intensity of the first laser and second laser beams.

Abstract: A high frequency modulator is described. It comprises: a first converter for receiving a constant current signal and transmitting a first converted signal; an adder coupled the first converter and operative for transmitting a summed signal in response to receiving the first converted signal and selectively receiving a triangular signal; a first oscillator coupled to the adder for receiving the summed signal, the first oscillator operative for transmitting a time varying current signal; a second converter coupled to the first oscillator for receiving the time varying current signal and operative for transmitting a second converted signal; and an output device selectively coupled to the second converter and operative for transmitting an output signal in response to receiving either the second converted signal or an offset signal.

Abstract: Disclosed is an improved DRAW technique for writing data on an optical storage medium and reading the data in parallel. In obtaining the optical power of a first light source 1, writing user data is temporarily suspended to write non-user data with a second light source 2 turned OFF.

Abstract: A circuit for preventing destruction of a semiconductor laser element of an optical disc device comprises a light-emission-directing circuit part for outputting a light-emission-directing signal for directing the semiconductor laser element to emit light; a voltage-monitoring circuit part for monitoring a light-emitting voltage and, when a judgment is made that the light-emitting voltage is normal, outputting a light-emission-permitting signal for permitting the semiconductor laser element to emit light, the light-emitting voltage being supplied from a power source for the semiconductor laser element to an optical-output-controlling circuit part in order to cause the semiconductor laser element to emit light; and a light-emission-permitting circuit part for using the optical-output-controlling circuit part to cause the semiconductor laser element to emit light only when the light-emission-directing signal and the light-emission-permitting signal are inputted.

Abstract: According to a method for setting the laser beam power applied to reproduce information recorded on an optical disc, information recorded in a region on the optical disc is reproduced using three or more test reproduction powers (S22B), the number of reproductions until the degradation of the quality of the reproduced signal reaches a prescribed value is determined as the degradation number of reproductions (S22F), the relation between the test reproduction power and the degradation number of reproductions is approximated by a curve, and a reproduction power restricting the degradation of the reproduced signal quality to a predetermined amount or less over a certain guaranteed number of reproductions is determined (S25F). In optical reproduction from an optical disc on which information is recorded, the optimum power of irradiation for reproduction can be set, and degradation of the information due to the reproducing light can be prevented.

Abstract: The invention relates to the field of the optical recording of information on a medium, such as an optical disc. To read an optical disc in super-resolution mode, a procedure for optimizing the power of the read laser beam is implemented. This optimization is based on the observation that a correlation exists between the power allowing the disc to be read without risk in super-resolution mode and the reflectivity of the sensitive layer containing the information. The reflectivity of the optical disc is measured for several power levels of the read laser, a critical power is determined on the basis of the reflectivity measurements made, and a read power sufficiently above the critical power, so as to be well outside a range of power levels entailing risks, is selected according to the critical power.

Abstract: The present invention is related to a method and a reading device (1) for retrieving information from an optical record carrier (10) in which the read power level of a radiation beam (3) for scanning the optical record carrier is set in dependence on the read-out speed. The invention is also related to a record carrier for use with such a method and a reading device.

Abstract: A record carrier is described comprising a zone with a visually detectable pattern composed of pattern elements arranged along at least one track. The pattern elements comprise a marked zone having an optical property deviating from a background, the marked zones having a width Wm transverse to the track direction and a length Lm along the track direction, wherein at least two or more pattern elements have a marked zone with a mutually different width Wm. In this way, an increased visibility of the visual pattern is achieved. Likewise a method and an apparatus for recording an optical record carrier is included.

Abstract: This invention provides an optical disc drive with more accurate and stable power control for a laser light source. An optical disc drive in an embodiment of this invention includes a monitor photodetector for receiving laser light emitted by a laser light source to monitor the laser light power. The monitor diode is a photodetector for generating an electric signal corresponding to the laser light power. A laser light controller controls drive current to the laser light source based on a result of measurement by the monitor diode. The optical disc drive measures output variations of the monitor diode and controls the gain of the monitor diode based on the result of the measurement. This gain control improves accuracy and stability in laser light control so that stability in recording/reading can be attained.

Abstract: There is provided a control device including a recording portion that records data on a disk by shining a laser beam onto a recording surface of the disk, a reading portion that reads the data on the disk, a control parameter computation portion that computes a control parameter, a differential computation portion that computes a differential between the control parameter and a value that is set in advance for the disk, a determination portion that determines whether the differential that the differential computation portion has computed is within a range of a dead band, an output value computation portion that computes an output value for the laser beam, an output control portion that controls the laser beam, a storage portion that stores a plurality of combinations of the dead band and the gain, and a selecting portion that selects one of the combinations of the dead band and the gain.

Abstract: A circuit for preventing destruction of a semiconductor laser element of an optical disc device comprises a light-emission-directing circuit part for outputting a light-emission-directing signal for directing the semiconductor laser element to emit light; a voltage-monitoring circuit part for monitoring a light-emitting voltage and, when a judgment is made that the light-emitting voltage is normal, outputting a light-emission-permitting signal for permitting the semiconductor laser element to emit light, the light-emitting voltage being supplied from a power source for the semiconductor laser element to an optical-output-controlling circuit part in order to cause the semiconductor laser element to emit light; and a light-emission-permitting circuit part for using the optical-output-controlling circuit part to cause the semiconductor laser element to emit light only when the light-emission-directing signal and the light-emission-permitting signal are inputted.

Abstract: An optical storage apparatus and a method for eliminating a write power transient thereof are provided. The method includes following steps. First, a target voltage level of a write voltage when next time the optical storage apparatus writes data is obtained. Then, a command value is updated by using the target voltage level according to a relationship between the command value and the write voltage. Next, the write voltage of the optical storage apparatus is pre-charged to the target voltage level according to the updated command value. Thereby, the write power transient of the optical storage apparatus can be eliminated.

Abstract: A method for monitoring an optical disk drive performance quality by determining a laser diode quality indicator for a laser diode arranged in an optical disk drive for scanning an optical disk, includes measuring an actual value of a parameter associated with a laser diode characteristic, obtaining a reference value of the parameter, comparing the actual value with the reference value for obtaining a comparison result, and determining the laser diode quality indicator from the comparison result. The laser diode quality indicator can at least take a warning level signaling a precursor for a defective state of the optical disk drive and an error level signaling a defective state of the optical disk drive. The laser diode characteristic may be a light-current or a voltage-current relationship.

Abstract: A laser diode write driver is described.

Abstract: An HF waveform prevailing during a read operation varies due, for instance, to changes in the ambient temperature of an optical disc drive and variations in the characteristics of a laser. This degrades read performance and decreases the number of rewritable disc read operations. To address the above problems, an optical disc drive and an optical information read method are disclosed. The disclosed optical disc drive and optical information read method vary an HF amplitude in relation to the resistance, differential resistance, or temperature of the laser.

Abstract: An optical disk drive controls recording power with high accuracy in accordance with a measured ? value and a target ? value. A system controller of the optical disk drive determines a ? value at which jitter or an error rate becomes minimum, in both an inner radius and an outer radius of an optical disk, and determines a difference between the determined ? value and the target ? value for each of the inner and outer radii. A corrected value for an arbitrary position, arbitrary speed, and an arbitrary temperature is calculated from a difference achieved at the inner radius and a difference achieved at the outer radius, by means of linear interpolation. The measured ? value for the arbitrary position, the arbitrary speed, and the arbitrary temperature is compared with the target ? value after having been corrected, thereby controlling recording power.

Abstract: In an optimal recording power calibration method for improving seeking stability on a recording power calibration area, a specific area serves as a data recording area during an optimal recording power calibration, wherein a length of the specific area is such that a plurality of times of optimal recording power calibrations can be performed. The method includes: an optimal recording power calibration step of recording, with different recording power, a first length of calibration data in the specific area, and calibrating optimal recording power, wherein a data sector recorded in this step is defined as a calibration recording sector; and a data recording step of recording, with data recording power, a second length of information having a logical address beside the calibration recording sector of the specific area, wherein a data sector recorded in the step is defined as an information recording sector.

Abstract: The present invention relates to methods for on-line calibrating output power of an optical pick-up. A power adjusting circuit of the optical pick-up has an optical power regulator and an optical power detector. The on-line output power calibrating method includes the steps of: performing a recording pre-process; providing a focus offset value and/or a tilt offset value to the optical pick-up; providing a setting value, corresponding to power under test, to the optical power regulator; detecting laser power emitted from the optical pick-up using the optical power detector; comparing the laser power with the power under test to adjust the setting value of the optical power regulator corresponding to the power under test; and performing an optimum power calibration if the laser power emitted from the optical pick-up conforms to the power under test.

Abstract: According to the present invention, heat generation amount control information for controlling a heat generation amount of a heat generating section (20) is arranged to correspond to each of temperatures so that a predetermined heat generation amount is obtained at each of the temperatures. The present invention includes a first computing section (41) that controls the heat generation amount of the heat generating section (20) according to the heat generation amount control information that is arranged in advance to correspond to temperature information that is obtained from a temperature sensor (13). This easily makes it possible to appropriately carry out at least either recording or reproduction with respect to a magnetic recording medium.

Abstract: A semiconductor light emitting device downsized by devising arrangement of connection pads is provided. A second light emitting device is layered on a first light emitting device. The second light emitting device has a stripe-shaped semiconductor layer formed on a second substrate on the side facing to a first substrate, a stripe-shaped p-side electrode supplying a current to the semiconductor layer, stripe-shaped opposed electrodes that are respectively arranged oppositely to respective p-side electrodes of the first light emitting device and electrically connected to the p-side electrodes of the first light emitting device, connection pads respectively and electrically connected to the respective opposed electrodes, and a connection pad electrically connected to the p-side electrode. The connection pads are arranged in parallel with the opposed electrodes.

Abstract: To determine the optimum amplitude of high frequency signal for the loaded disc with a simple configuration to achieve stable playing performance, there is provided an optical disc device comprising: a light source driven by a drive signal with a high frequency signal superimposed; a detector for detecting return light emitted from the light source; and a controller for controlling amplitude of the high frequency signal to be superimposed on the drive signal for the light source; the optical disc device being configured to read data on an optical disc loaded therein by a signal outputted from the detector, wherein the controller determines the amplitude of the high frequency signal to be superimposed on the drive signal based on asymmetry of the signal outputted from the detector.

Abstract: An optical disc apparatus for recording or reproducing on or from an optical disc, comprising a laser light source for emitting a laser beam; a drive portion for driving the laser light source; a detection portion for detecting the emission power of the laser beam; and means for focusing the laser beam onto the optical disc, wherein information is reproduced by a reproducing power varied according to a recording power to obtain reproducing signals having necessary quality while suppressing deterioration of the recording quality due to the reproducing power.

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.