Abstract: A disk drive determines whether or not a currently loaded disk is a gravity center deviated disk based on a tracking error signal detected at different disk rotation speeds.

Abstract: The invention relates to an optical disc device and a control method for the optical disc device. The presence of defects on an optical disc is confirmed by, based on the result of detecting a return light corresponding to a sub-beam spot used for tracking control, which is formed on the preceding side with respect to scan of a main beam spot, suppressing changes in signal level of the light detection result caused upon boosting of the laser power of a laser beam. Also, whether data can be correctly reproduced is determined by, based on the result of detecting a return light corresponding to a sub-beam spot used for tracking control, which is formed on the succeeding side with respect to scan of the main beam spot, suppressing changes in signal level caused upon writing of the data. Therefore, whether data can be correctly reproduced can be confirmed with a simple construction while effectively avoiding a reduction of the data transfer rate.

Abstract: The astigmatic aberration in an optical system is to be adjusted. Specifically, in an optical disc device on which can be selectively loaded a first optical disc having a first index of double refraction or a second optical disc having a second index of double refraction larger than said first index of double refraction, and which includes a liquid crystal device 31 between a light source 11 and an objective lens 15 converging a light beam radiated from said light source on the optical disc 2 loaded on the optical disc device, the voltage applied to the liquid crystal device 31 is adjusted to correct the coma aberration or the astigmatic aberration for the first disc or the second disc, respectively.

Abstract: A plurality of tracks on an optical disk are optically read to obtain a signal containing a plurality of LOW segments. Each of the plurality of LOW segments should correspond to a certification pit. Accordingly, if the interval between LOW segment Xj and nth succeeding LOW segment Xj+n exceeds the length of one track, a defect pit that could be confused with a certification pit is judged as being present between two certification pits.

Abstract: An optical disk apparatus includes a laser diode, and a light from the laser diode becomes a parallel light by a collimator lens, which is reflected toward an object lens by a reflection mirror. The parallel light transmitted through a through-hole provided on an object lens holder is reflected by a disk, and a reflected light is incident upon a light-receiving sensor via the collimator lens, a polarizing beam splitter and a prism. The parallel light reflected by the reflection mirror is reflected by a mirror integrated with the object lens holder, and incident upon the light-receiving sensor via the collimator lens, the polarizing beam splitter and the prism. A disk tilt and/or an object lens tilt are/is detected from output signals of divided light-receiving sensors of the light-receiving sensor.

Abstract: An apparatus includes a controller storing information on dense/sparse state of the tracking error signal in connection with characteristic of the signal generated by a phase encoder while tracking servo of a servo unit is inactivated, and, in data reproduction mode, identifying a current disk phase based on characteristic of the signal generated by the phase encoder, and adjusting tracking characteristic of the servo unit based on the stored information in connection with the signal characteristic in order to compensate an effect rate of eccentricity on the identified disk phase. Through minute adjustment of servo characteristic for each disk phase, error range of TE signal to track in real time is reduced. Therefore, tracking for an eccentric disk becomes easier and more reliable.

Abstract: An optical head with excellent optical characteristics even when using a light source that substantially has a wavelength broadening is provided. The optical head includes a light source, an objective lens for focusing a light beam emitted from the light source on an information recording medium and a photodetector for detecting the light beam reflected from the information recording medium, wherein defocusing correction means and spherical aberration correction means are provided in an optical path between the light source and the information recording medium. Since both the defocusing correction means and the spherical aberration correction means are provided, while defocusing of a focused spot on the information recording medium caused by a wavelength broadening of the light source and chromatic aberration of the optical system can be corrected, the spherical aberration of the optical system caused by wavelength difference between a design wavelength and an incident wavelength also can be corrected.

Abstract: In an optical head device and an optical information recording/reproducing device using the optical head device, by driving a liquid crystal panel 4a, the liquid crystal panel 4a produces wave aberration for light on a going path and light on a returning path likewise. Accordingly, when the substrate-thickness deviation or tilt of the disc 7 is corrected, the wave aberration due to the substrate-thickness deviation or tilt of the disc 7 and the wave aberration produced by the liquid crystal panel 4a are canceled by each other for both of the light on the going path and the light on the returning path, so that no wave aberration remains for the light on the returning path and the phase distribution is not varied.

Abstract: It is an object of the present invention to provide an optical pickup apparatus appropriate for the notebook PC that can prevent structural resonance of the lens holder by arranging the focus coil and the tracking coil in a way to stabilize the weight balance, enable the tilt servo, and be composed in an extremely reduced thickness. An optical pickup apparatus composed to adjust the irradiation position of light beam to an optical disk by displacing an objective lens through a driving control of a lens holder holding the objective lens with a moving coil method, wherein an objective lens driving section is composed by arranging and fixing focus coils 7a, 7b so that a pair of coil main bodies be symmetrical about the objective lens 4 arranged at the middle of the lens holder 4, and arranging a pair of tracking coils 8a, 8b, 8c, 8d at both sides of the respective focus coils.

Abstract: An eccentricity compensating apparatus of a disk drive servo system using frequency response characteristics of an actuator actuating a head to a position on a disk to read data on or reproduce data from the disk. The apparatus includes an error detector that detects a position error between a reference head position and an actual position of the head on the disk and a first compensation controller that receives the position error from the error detector and changes the actual position of the head to compensate for the position error.

Abstract: An objective lens supporting apparatus of an optical pickup includes a lens frame in which an objective lens is mounted; receiving member for receiving driving forces for displacing the objective lens in the direction of the optical axis and in a direction perpendicular to the optical axis is disposed; a support base in which generating member for generating the driving forces is disposed; an elastic member W extended from the support base and fixed to the lens frame for swingably supporting the lens in a cantilevered manner; and a tilting member for inclining the optical axis of the objective lens with respect to the support base by tilting the lens frame.

Abstract: An optical pickup lens device includes, in the order from the light source side, collimating means for converting a bundle of rays into parallel rays or predetermined convergent or divergent rays, the collimating means being movably held along a direction of an optical axis of a bundle of rays emitted from a light source; an aberration correcting element for allowing a bundle of rays emitted from the collimating means to be transmitted therethrough; and an objective lens element having a numerical aperture of 0.8 or more, and converging a bundle of rays coming from the aberration correcting element onto the information recording medium to form a spot. The aberration correcting element and the objective lens element are integrally held together in a direction orthogonal to the optical axis so as to perform tracking on the information recording medium, and satisfy predetermined conditions.

Abstract: An optical disk medium and a drive system are provided that enable high density recording to be carried out. In the optical disk medium, recorded information tracks are formed in a concentric or spiral manner, and information is recorded and played back by irradiating the recorded information tracks with a laser beam through a transparent substrate or a transparent cover layer. A change in tilt of the optical disk medium over one circuit of each of the tracks is set equal to or less than an allowed value, a change in tilt over the entire surface of the optical disk medium is permitted to be larger than the allowed value, and low frequency bandwidth tilt control is carried out by the drive system.

Abstract: An optical system of an optical recording apparatus forms a main spot and sub-spots preceding and succeeding the main spot on a signal recording medium. The optical system is set such that the sub-spot is shifted from the main spot in the direction orthogonal to a signal track by a distance expressed by an expression (2k?1)P/4(k=natural number), in which P denotes a distance between adjacent signal tracks on the signal recording medium. Thus, the sub-spot succeeding the main spot can be used to effectively read the state of a signal recorded on the signal recording medium by the main spot.

Abstract: The present invention provides a method for adjusting the mechanical error of an optical disc reading device. The optical disc reading device consists of a driving device and an optical pickup. The driving device has a base plate for supporting and rotating an optical disc. The method consists of moving the optical pickup to surface of optical disc, the optical pickup emitting two tracking light spots onto the surface, and the optical pickup reciprocally moving relative to the surface. Next, the optical pickup reads reflected signal of two tracking light spots for generating a track crossing signal. By using the track crossing signal, the method adjusts position of optical pickup relative to the base plate.

Abstract: In a method of controlling data reproduction in an optical disk drive, when a decoding error occurs, decoding is performed by changing a servo parameter. Thus, the decoding errors are reduced while playability is improved. The method of controlling data reproduction in an optical disk drive for reading data stored on an optical disk is performed by monitoring whether a decoding error occurred at a host part, if a decoding error occurred, changing a servo parameter for adjusting balance and/or offset of error signal which input to servo system, and rereading a portion on the optical disk medium where the decoding error occurred using the changed servo parameter and performing decoding.

Abstract: An exposure apparatus for an optical disc used for eliminating the vibrations in the propagating direction when a rotation mechanism rotates. The slider controller 40 and the spindle controller 41 of the exposure apparatus 1 are activated, and the then the optical disc begins to be rotated by an AC synchronized motor. Through a condensing device 9, laser beams emitted form the laser source 6 are irradiated on the optical disc for exposure. At this time, the optical disc is eccentrically chucked on the rotation mechanism, resulting a rotational vibration of the whole rotation mechanism. A measurer 17 is used for detecting a propagating component of the rotational vibration, and a vibrator controller 42 controls the vibrator 20 as the output of the measurer 17 approaches zero. Therefore, the vibration in the propagating direction of the base 2 is cancelled, and the propagation accuracy is increased and the exposure quality is enhanced.

Abstract: An optical disc apparatus comprises: rotating means for rotating an information recording medium; a light source for irradiating a light beam onto a data side of the information recording medium; converging means for converging said light beam; focus error detecting means for detecting a difference between said data side and the focus of the light beam converged by said converging means; focus direction transferring means for transferring said converging means in a direction perpendicular to said data side; focus controlling means for driving said focus direction transferring means based on the output of said focus error detecting means in such a way that said light beam converges on said data side in a predetermined state; tracking direction transferring means for transferring said light source in the radius direction of said information recording medium; and tilt calculating means for calculating average values of the outputs of said focus controlling means obtained for a period of time, which is an integer

Abstract: An optical disk apparatus is constructed for writing or reading information by irradiating a laser beam onto an optical disk while rotating the optical disk under a focus control of the laser beam relative to the rotated optical disk. In the optical disk apparatus, an irradiating section is operated to irradiate a laser beam onto the optical disk. A determining section determines a process pattern of the focus control by operating the irradiating section to irradiate the laser beam onto a predetermined area of the optical disk and by monitoring the laser beam reflected back from the predetermined area. A focusing section performs the focus control to regulate a spot diameter of the laser beam based on the determined process pattern during either of the writing or reading of information.

Abstract: An optical information recording method and a device which can record information with a laser light irradiating direction kept constant even if an information recording surface of an optical information recording medium is inclined and, a recording medium having a program therefor recorded thereon are provided. When performing OPC, a relational expression between a recording power and asymmetry (a standard expression), a relational expression between a differential light intensity value and a recording power (a first detection expression), a relational expression between a recording power and a difference between a differential light intensity value and a reflected light amount ratio (a second detection expression), a relational expression between a reflected light amount ratio and a recording power (a third detection expression), a differential light intensity value with which optimum asymmetry can be obtained, a recording power, a reflected light amount ratio and the like are determined and stored.

Abstract: Herein disclosed is a optical disc driving apparatus for driving an optical disc having a central axis, comprising: a turntable having a central axis, said turntable being adapted to retain an optical disc under the condition that said central axis of said turntable is axially aligned with said central axis of said optical disc; an optical pickup unit movable toward and away from said central axis of said turntable, said optical pickup unit being adapted to write or retrieve information from said optical disc retained by said turntable; a stepping motor having a plurality of coils; a detecting unit for detecting an exterior vibration while being vibrated in response to said exterior vibration; a driver IC for controlling said stepping motor to have said stepping motor assume two different operation states consisting of a first operation state to drive said stepping motor to ensure that said optical pickup unit is moved toward and away from said central axis of said turntable, and a second operation state to d

Abstract: An optical disk apparatus configured to be compatible with a plurality of disk types includes an objective lens to focus a laser beam onto an optical disk provided in the apparatus. A drive mechanism is coupled to the objective lens to enable tilting of the objective lens to a plurality of tilt angles. A first signal detection circuit is configured to receive and process a first information signal associated with information read from the optical disk and to output a data signal derived from the first information signal. A second signal detection circuit is configured to receive and process a second information signal associated with information read from the optical disk and to generate a first track error signal. A third signal detection circuit is configured to receive and process a third information signal associated with information read from the optical disk and to generate a second track error signal.

Abstract: An object of the present invention is to provide an optical pickup apparatus which changes characteristics of a light-emitting device or hologram to reduce problems of track servo deviation due to scratches on a surface of an optical disc. By aligning a photoreceptive domain for focusing error signal (PDf) and a photoreceptive domain for tracking error signal (PDt), even in a case where scattering light made by a scratch in the tangent direction of a track of an optical disc reaches the photoreceptive domains, light diffracted in a HA+B domain of a hologram pattern does not enter into photoreceptive portion F or G of the PDt. Therefore, scattering of light which enters the PDf does not influence a tracking error signal (TES), so that the TES does not become abnormally large, and track servo deviation can be prevented.

Abstract: An optical pickup apparatus for an optical disk drive records or reproduces data on or from an optical disk, includes an optical head section including an object lens focusing an incident light on the optical disk, a slider on which the object lens is mounted, wherein the slider floats over the optical disk by an air bearing generated between the optical disk and the slider, a bobbin on which the slider is mounted, and a flexure disposed between the slider and the bobbins elastically supporting the slider. A driving unit drives the slider in a tracking direction and a focusing direction. In the above construction, the slider floats over a recording surface of the optical disk due to an air bearing and a near field between the object lens and the optical disk can be controllably maintained.

Abstract: A tilt servo control device of an apparatus for recording information on and reproducing information from an optical recording medium set in the apparatus, the apparatus comprising an optical system for leading a laser beam emitted from a light source to a recording surface of the optical recording medium and a laser beam reflected by the recording surface of the recording medium to a photo detector and a read signal generator for generating a read signal in accordance with an output signal of the photo detector. The tilt servo control device determines a type of the optical recording medium, generates a tilt drive signal so as to reduce a tilt angle at a position of the laser beam irradiating the recording surface and an optical axis of the laser beam by a method for generating a tilt drive signal corresponding to the recording medium type, and drives a tilt angle adjuster for adjusting the tilt angle in accordance with the tilt drive signal.

Abstract: According to the present invention, it is intended that the recording can be executed normally even against small vibrations to which a servo error signal detecting circuit cannot respond. A recording apparatus according to the present invention includes an optical head (12) for receiving a reflected laser beam (LREF) obtained when a laser beam (LIRR) is irradiated on a CD-R (10). This recording apparatus further includes a gate circuit (31) to which an output signal (SRD) of the optical head (12) is supplied and a level comparing circuit (34) for comparing a value of an output signal (DTAU) of this gate circuit (31) with a predetermined reference value (DTH). Upon recording, the gate circuit (31) is controlled in such a manner that a signal of a predetermined period ? may be outputted from the output signal (SRD) supplied from the optical head (12) to the gate circuit (31) as the output signal (DTAU).

Abstract: An offset measuring method is for measuring an offset based on an optical beam reflected by an information medium, in a recording and reproduction apparatus including an optical pickup placed on transportation means so as to be driven along a radial direction of the information medium. The method includes the steps of directing an optical beam toward a first measuring position, thereby measuring a first offset amount based on the optical beam reflected at the first measuring position; moving the transportation means by a first distance in a first direction along the radial direction; driving the optical pickup by a second distance, which is equal to the first distance, in a second direction; and directing an optical beam toward a second measuring position, thereby measuring a second offset amount based on the optical beam reflected at the second measuring position.

Abstract: In a method and an apparatus for aberration correction according to the invention, aberration occurring in recording/reproducing information derived from causes such as thickness variation of a substrate, a tilt, a focus error and a tracking error is detected, and the aberration is corrected by correcting these causes.

Abstract: An apparatus for generating push-pull signals is disclosed. The apparatus, used in an optical-disk apparatus, includes a first signal-adjusting circuit, a second signal-adjusting circuit, gain-determining means, and a difference-signal generating circuit.

Abstract: A tilt servo apparatus for use in a ROM system includes means for generating a reconstructing beam to be projected onto a digital storage medium to generate a reflected beam; a holographic plate for storing a first and a second hologram and diffracting the reflected beam with the first and the second hologram to generate a first and a second holographic diffracted beam, respectively; a first and a second detector for generating a first and a second detected signal by detecting the first and the second holographic diffracted beam, respectively; means for generating a tilt servo signal based on the first and the second detected signal; and means for compensating a tilt error of the digital storage medium by using the tilt servo signal.

Abstract: Suspension wires (3a) and (3c) are fixed to and bridged over a lens holder (1) and a fixing member (11) which is fixed to the housing. On each of side surfaces of the lens holder (1) is mounted a tilt bobbin (8) onto which a tilt coil (9) is wound. A second suspension wire (3b) is fixed to and bridged over the tilt bobbin (8) and the fixing member (11).

Abstract: An adjustment method for optical pick-up including a light source for emitting light beams, an object lens for irradiating light beams onto an optical disc for adjustment and a drive portion for driving the object lens in a direction in parallel to the optical axis of the object lens and in a direction perpendicular to the optical axis thereof, wherein in the state where the light source is movably held with respect to the object lens and the drive portion is movably held with respect to the light source, light beams are irradiated onto an optical disc for adjustment concentrically having recording tracks from the optical pick-up to adjust relative position of the object lens with respect to the light source and inclination of the optical axis of the object lens, and an optical disc for adjustment used in such an adjustment method.

Abstract: A spindle motor inclination angle adjusting mechanism for an optical disk device includes two adjusting mechanisms to provide two rotational freedom for the base dock of the spindle motor to adjust the inclination angle of the spindle motor. The first adjusting mechanism has three support points that are not on the same straight line to support the base dock. Two of the support points are fixed and the third support point is movable relative to the other two support points to change the inclination angle of the base dock of the spindle motor. The second adjusting mechanism is a rotary element for carrying the first adjusting mechanism and driving the first adjusting mechanism to rotate and change the direction of the inclination angle of the base dock to adjust the spindle motor inclination angle.

Abstract: An objective lens driving apparatus is used for accurately positioning an abject to focus a light spot on an optical recording medium. A lens holder holds the objective lens and has a bearing hole through which a shaft extends in a direction parallel to the optical axis so that the lens holder is rotatably supported on the shaft. Two magnets are supported on the lens holder so that the shaft is between the magnets. A base has two magnetic members disposed such that each of the two magnets exerts an attraction force on a corresponding one of the two magnetic members to urge the lens holder in a direction of the optical axis and in a direction perpendicular to the optical axis. A first coil set of first focusing and tracking coils and a second coil set of focusing and tracking coils are mounted to the two magnetic members.

Abstract: An adjustment method for optical pick-up including a light source for emitting light beams, an object lens for irradiating light beams onto an optical disc for adjustment and a drive portion for driving the object lens in a direction in parallel to the optical axis of the object lens and in a direction perpendicular to the optical axis thereof, wherein in the state where the light source is movably held with respect to the object lens and the drive portion is movably held with respect to the light source, light beams are irradiated onto an optical disc for adjustment concentrically having recording tracks from the optical pick-up to adjust relative position of the object lens with respect to the light source and inclination of the optical axis of the object lens, and an optical disc for adjustment used in such an adjustment method.

Abstract: Monitor circuits monitor junction temperatures of chips of driver ICs which drive a driving part of a recording/reproduction system. Comparison circuits compare the junction temperatures with respective arbitrarily set temperatures to output temperature flags as comparison results and are included in the driver ICs. A CPU monitors the temperature flags to confirm febrile states of the respective driver ICs, thereby performing a control so as to continue to drive an optical disk device when the junction temperatures of the chips of the driver ICs are lower than the set temperatures, and to suppress heat generation of the respective driver ICs when the temperatures are equal to or higher than the set temperatures.

Abstract: An optical disk drive for accessing data stored on a compact disc has a housing, a sled sliding inside the housing, a driving device for driving the sled, an actuator installed on the sled, a servo device for providing a push force to drive the actuator, a control circuitry for controlling operations of the optical disk drive, an adaptive compensator, and an error signal generation circuit. The actuator can move within a predetermined range on the sled, wherein the predetermined range includes a linear region and a non-linear region. It is desirable to keep the actuator within the linear region of the predetermined range. For this, an adaptive compensator is used to provide a supplementary force to the sled when the actuator is near the non-linear region.

Abstract: Disclosed is an optical pick-up actuator configured to achieve a multiaxial driving operation using a combination of a moving magnet system and a moving coil system. The optical pick-up actuator includes a first magnet unit, and a second magnet unit. The first magnet unit serves to conduct a tilt compensation, and the second magnet serves to conduct focusing and tracking operations. The first magnet unit for the tilt compensation is configured to conduct a tilt compensation in a tangential direction and a tilt compensation in a radial direction in an independent fashion.

Abstract: An optical pickup device including a light source, an objective lens for converging a light beam emitted from the light source at a signal recording surface of an optical recording medium and irradiating the signal recording surface of the optical recording medium with the light beam, and a liquid crystal device, disposed in a light path between the light source and the objective lens, for giving a predetermined phase distribution to transmission light that passes through the liquid crystal device, with both front and back surfaces of the liquid crystal device being flat surfaces. In the optical pickup device, the liquid crystal device is constructed by sandwiching a liquid crystal molecule layer by a pair of transparent substrate.

Abstract: A tracking servo apparatus in which reflection light obtained when a laser beam is irradiated onto a recording surface of an optical disc is photoelectrically converted, thereby obtaining a photoelectric conversion signal, a tracking error signal showing a deviation amount of an irradiating position of said laser beam for a track in a disc radial direction on the recording surface is generated by the photoelectric conversion signal, a spherical aberration occurring in an optical system is detected, a level of the tracking error signal is corrected on the basis of the detection result, and the irradiating position of the laser beam is moved in the disc radial direction in accordance with the level-corrected tracking error signal.

Abstract: A method for determining a direct current (DC) level involved in an alternating current signal is provided. The alternating current signal is transmitted from an amplifier to an A/D (analog-to-digital) converter. When any of the extreme values of the alternating current signal is beyond the input range of the A/D converter, the alternating current signal is shifted to make both of the peak and bottom values located within the input range of the A/D converter. Then, the real extreme values are realized according to the shift level(s), the relative peak and bottom values realized after the shifting procedure, and the input range of the A/D converter. Finally, the DC level is determined according to the real peak and bottom values.

Abstract: A disk apparatus includes a DSP (digital signal processor), and the DSP controls respective circuit components under instructions of a MCU. During a track jump, a DSP core detects a zero-cross cycle of a TE (Tracking Error) signal just before. If a detected zero-cross cycle is delayed than a target value, the DPS core applies an acceleration pulse of a first predetermined level to a driver, and if the zero-cross cycle is faster than the target value, the DPS core applies a deceleration pulse of a second predetermined level to the driver, whereby an objective lens can be controlled to move at approximately constant speed between adjacent tracks. However, if the zero-cross cycle is considerably delayed than the target value, the DSP core forestalls a reverse rotation of a moving direction of the objective lens against the disk by greatly accelerating the objective lens. Therefore, the number of tracks to have been jumped is not to be counted erroneously.

Abstract: A tracking control method measures an optimum offset by measuring a light beam irradiation state of a light beam while offsetting a tracking target position of the light beam on a recording medium so that an optimum light beam irradiation state is obtained at the tracking target position, and carries out a tracking control by setting the measured optimum offset.

Abstract: An optical storage system includes a pickup head for picking up data from a storage medium. Firstly, the maxima of a tracking error signal and runout are obtained in a calibration procedure in a close loop formed by an optical pickup head, a pre-amplifier, a compensator, a band-pass filter and a maximum detector. A calibration factor is then defined and derived by using the obtained maxima and nominal factors of a power amplifier and the optical pickup head of the optical storage system. The path formed by the series-connected band-pass filter and maximum detector is then disabled, while the calculated calibration factor is then stored in the compensator. The optical storage system may operate in a close loop formed by the optical pick head, pre-amplifier, compensator, a power amplifier under a normal operation procedure so that the optical storage system may record or read data onto/from an optical disc under the compensation provided by the calibration factor.

Abstract: Disclosed herewith is a method of compensating for the seek errors of a pickup assembly. The method includes the steps of calculating a target track number to read data stored in an optical disc by transferring a pickup assembly across the optical disc; determining whether a seek error has to be compensated for in a radially outward direction of the optical disc; if the seek error has to be compensated for in a radially inward direction, compensating for the seek error; transferring the pickup assembly in the radially inward direction, reading an address of a current position of the pickup assembly, and determining whether the current position of the pickup assembly coincides with a target position; if the current position of the pickup assembly coincides with the target position, calculating the seek error in a radially inward direction and calculating an error compensation value in a radially inward direction; and storing the calculated error compensation value and using it to perform a next seek operation.

Abstract: Systems and methods are provided through which the current to a spindle motor of the recording medium of a mass storage device is modulated to avoid anomalies in the operation of mass storage device and reduce power consumption. In the example of a disc drive, the current is modulated to prevent expected or predicted disturbances in the air bearing between a read/write head and the recording medium, and to reduce the power consumption when no disturbances are predicted or expected.

Abstract: A differential phase detection device receives first through fourth detection signals from a photodetector and detects a differential phase signal therefrom, the differential phase detection device includes a slicer slicing and digitizing each of the detection signals with respect to a reference level. A synthesizer synthesizes the digitized detection signals and generates therefrom synthesis signals. A phase difference detector compares phases of the synthesis signals and outputs a first phase difference signal and a second phase difference signal. A matrix circuit processes the first and second phase difference signals to output the differential phase signal.

Abstract: A circuit element driver includes a control section and a driving section. The control section receives a number n of instruction values of a first group (where n?2) and produces and outputs a number p of instruction values of a second group (where (n+1)?p<2n) in accordance with the n instruction values of the first group. The instruction values of the first group are issued to generate voltages to be applied to n two-terminal circuit elements. The driving section generates and outputs p drive voltages in accordance with the p instruction values of the second group. At least one of the p drive voltages changes with at least one of the instruction values of the first group and is applied in common to two or more of the circuit elements at one terminal thereof.

Abstract: A tilt servo control device of an apparatus for recording information on and reproducing information from an optical recording medium set in the apparatus, the apparatus comprising an optical system for leading a laser beam emitted from a light source to a recording surface of the optical recording medium and a laser beam reflected by the recording surface of the recording medium to a photo detector and a read signal generator for generating a read signal in accordance with an output signal of the photo detector. The tilt servo control device determines a type of the optical recording medium, generates a tilt drive signal so as to reduce a tilt angle at a position of the laser beam irradiating the recording surface and an optical axis of the laser beam by a method for generating a tilt drive signal corresponding to the recording medium type, and drives a tilt angle adjuster for adjusting the tilt angle in accordance with the tilt drive signal.

Abstract: An information recording apparatus includes: an information recording part performing information recording on a recording medium divided into a plurality of sectors each including a plurality of information units; a prediction part detecting or predicting an occurrence of a recording failure during the information recording; a suspension control part suspending the information recording at the present one of the information units of the recording medium and storing suspension information indicating a suspension position where the information recording is suspended; a determination part determining whether the recording failure is over after the suspension of the information recording; and a resumption control part causing the information recording part to resume the information recording at a position determined based on the suspension information so that information is continuously recorded on the recording medium over the suspension position.