Abstract: Data detection capability is improved by whitening crosstalk noise from an equalization signal and detecting binary data. Each of a plurality of detection signals is input to one of a plurality of adaptive equalizers, and outputs of the plurality of adaptive equalizers are computed to obtain an equalization signal for returning light at the time of shining of light onto bounds including a target track subject to data detection and adjacent tracks of an optical recording medium having a plurality of tracks formed thereon. Crosstalk noise from the adjacent tracks included in the equalization signal obtained by this multi-input adaptive equalization process is whitened first, followed by a binarization process. Also, an equalization error is found, and supplied as a control signal for adaptive equalization. Further, a whitening factor updating process is also performed to adaptively update a filter factor of a whitening filter.

Abstract: In a system of detecting an interference light with a light not irradiated onto an optical disc to increase the S/N ratio, it is difficult to stably acquire a reproduced signal with a simple configuration. Since the recording density is not improved, an improvement in transfer rate is difficult. In an optical information recording/reproducing apparatus where two optical beams face each other and are focused at the same place of a recording medium to record a standing wave developed by interference of the two optical beams, a phase difference of the two optical beams is modulated in a multiple stage and recorded. During reproduction, an interference light of a reproduced light from the recording medium and another reproduction reference light is detected as a reproduced signal, and a phase servo control stabilizing the phase of interference during reproduction by using a low frequency component of the reproduced signal is conducted.

Abstract: In a small-sized optical pickup device for enabling to obtain a stable servo-signal, as well as, a focus error signal and a tracking error signal, without receiving ill influences of stray lights from other layers, when recording/reproducing a multi-layer optical disc, a reflection light from the multi-layer optical disc is divided into plural numbers of regions by a diffraction grating. And, it is divided into at least four (4) regions, by a division line in the tangential direction of the optical disc and a division line in the radial direction thereof. Light receiving parts, for detecting either one of grating diffraction lights, i.e.

Abstract: An optical disc device comprising: a controller for reading data from an optical disc having a plurality of recording layers, wherein: the controller, in shifting a focus of the laser light from a first layer to a second layer, performs a first change that changes a setting on the high frequency signal to a predetermined value at which the high frequency signal is superimposed to suppress peak power of the drive signal if a light density of the second layer is higher than a light density of the first layer; the controller shifts the focus from the first layer to the second layer; and the controller, after the focus has been shifted, performs a second change that changes the setting on the high frequency signal to a predetermined value at which the high frequency signal is superimposed to increase the peak power of the drive signal.

Abstract: An approach is described that allows an optical disc drive to accurately verify the power level of irradiation beam power levels associated a write strategy used in high speed, high density optical disc media formats using a front monitor diode with a relatively slow rise time and/or relative slow fall time compared to the clock cycle speed of the write strategy signal. A portion of encoded data to be written to an optical disc media may be overwritten to include a predetermined data pattern. During write strategy processing of the data, the predetermined data pattern is replaced with a constant write strategy power level. The constant write strategy output placed within the write strategy signal may control the optical disc drive laser to emit a constant irradiation beam for a duration sufficiently long to allow the front monitor diode to obtain an accurate measure of the irradiation beam power level.

Abstract: Circuitry for controlling mode selection of a CD/DVD reader is described. In one embodiment, the CD/DVD reader has a first device having at least one analog output, a second device having at least one digital input and at least one analog input, and an interface circuit coupling the analog output of the first device to the digital input and the analog input in the second device. The interface circuit includes a circuitry to use a single control signal from the analog output of the first device to control the digital input and the analog input in the second device. Other embodiments are also described.

Abstract: An optical pickup and an information storage medium system using the same. The optical pickup includes a light source that emits light having a plurality of different wavelengths. The optical pickup includes a diffraction device having a plurality of diffraction patterns corresponding to the plurality of different wavelengths to divide the light incident from the light source unit into main light and sub light. The optical pickup further includes a photo-detector having a first main light reception unit that receives the main light and a first sub light reception unit that receives the sub light so as to detect an information signal and/or an error signal by receiving reflected light. The first sub light reception unit of the photo-detector is shaped so as to reduce reception of noise sub light due to diffraction based on an undesired diffraction pattern of sub light generated the diffraction device.

Abstract: A focus servo control device includes a first detector, first controller, second detector, and second controller. The first detector detects a first focus error signal. The first controller controls the objective lens based on the first focus error signal, so that a focal point of the first laser agrees with the guide layer. The second detector detects a second focus error signal. The second controller changes a relative distance between the focal point of the second laser and the focal point of the first laser, so that the focal point of the second laser agrees with a target recording/reproducing layer.

Abstract: For obtaining stable servo-signals without receiving ill influences of stray lights from other layers, on both a focus error signal and a tracking error signal, when recording/reproducing a multi-layer optical disc having small gap between layers thereof, a light beam is divided with using a first and a second diffraction gratings. The first diffraction grating is a polarization diffraction grating, and is mounted on an actuator. The second diffraction grating is disposed on a fixed portion. The first diffraction grating has a first region having a center of a light beam and other(s), and among signal lights reflecting from the disc, the light beam entering into the first region is diffracted, and the light beam entering into the second region transmits therethrough. The second diffraction grating transmits the light beam diffracting on the first region of the polarization diffraction grating therethrough, while diffracting the light beam diffracting on the second region.

Abstract: An optical information reproducing apparatus includes: an irradiation section irradiating a light beam onto an optical information recording medium, in which holes are formed along a virtual track on a recording medium, along the virtual track; a light receiving section receiving a reflected light beam when the light beam is reflected by the optical information recording medium and sequentially generating a light receiving signal corresponding to the light intensity; a detection section detecting a variation pattern appearing when a signal level of the light receiving signal changes according to the hole; and a code string generating section, when generating a code string corresponding to the signal level, generating a code corresponding to the one hole from the variation pattern if the variation pattern falls within a range and generating a code string, which includes a plurality of codes, from the variation pattern if the variation pattern exceeds the range.

Abstract: An optical pickup device includes an astigmatism element which imparts astigmatism to laser light reflected on a disc, a spectral element which changes propagating directions of four light fluxes obtained by dividing a light flux of the laser light reflected on the disc to disperse the four light fluxes from each other, and a photodetector having a sensor group which receives the four light fluxes. The optical pickup device is further provided with a memory which holds a correction value for suppressing a DC component in a tracking error signal resulting from a positional displacement of the spectral element. The tracking error signal is corrected by the correction value to thereby suppress the DC component.

Abstract: An optical pickup includes a light source, an objective lens, a diffraction grating that divides an optical beam reflected from a predetermined information layer, into a plurality of optical beams, and a detector having a plurality of photo-receivers to receive a plurality of optical beams. The diffraction grating has a predetermined region for dividing from a signal light beam a region including a central portion of a spot which the signal light beam will form on the diffraction grating. A distance from a central section of the detector to that of a spot center photo-receiver on the detector, the spot center photo-receiver being provided to receive the optical beams formed by division in a predetermined region of the diffraction grating, is equal to or greater than a spot radius of the unwanted light beams entering the predetermined region of the diffraction grating, on the detector.

Abstract: An optical-pickup apparatus includes: a first laser light source including a first laser diode to emit a laser beam having a first wavelength, and a back-monitor photodetector to receive the laser beam emitted in a backward direction, not being an optical-disc direction, and output a first monitor signal; a second laser-light source including a second laser diode to emit a laser beam having a second wavelength; a light-receiving circuit including a front-monitor photodetector to receive the laser beam emitted in a forward direction, being the optical-disc direction, and output a second monitor signal, and a switch circuit to be inputted with the first and second monitor signals, and output the first or second monitor signal according to a switch signal; and first and second drive circuits to drive the first and second laser diodes according to the first and second monitor signals outputted from the light-receiving circuit, respectively.

Abstract: An optical pickup having a one-plane, two-wavelength diffraction grating and a two-wavelength laser generator is provided in which crosstalk noise caused by leakage of a track error signal into a focus error signal is reduced to improve focus control performance. A main beam and sub-beams generated by the one-plane, two-wavelength diffraction grating and reflected from the surface of an optical disc are incident on corresponding light receiving elements among which the one to receive the main beam and those to receive the sub-beams are relatively shifted in a linear-speed direction of the optical disc. The distance of the shifting is determined based on the characteristic, relative to the relative positions of the light receiving elements, of the leakage of the tracking error signal into the focus error signal detected based on the main beam and sub-beams.

Abstract: An optical disc apparatus includes an optical pickup including: a light source; an objective lens for converging a light flux emitted from the light source and forming an optical spot on an information recording plane of an optical disc; and an optical modulation unit divided into a plurality of areas for modulating an area containing a main beam of the light flux to change a shape of the optical spot, wherein data is reproduced by converting a reproduction signal read from the optical disc with the optical pickup into an NRZI signal of a predetermined modulation rule by a PRML method. An optical spot shape, laser power setting and PRML setting are changed with each optical disc and each drive operation state.

Abstract: Provided is an optical pickup including: a light-source emitting a light-beam; an objective lens collecting the light-beam on a desired recording layer among one or two recording layers or more installed in an optical disc and where spirally- or concentrically-shaped tracks are formed; a lens-moving unit moving the objective lens in a tracking direction toward at least an inner-circumference or outer-circumference side; a light splitting device splitting a reflected light-beam into reflected light-beams and propagating the light-beams; a light-detecting device generating central, inner-circumference-side, and outer-circumference-side light-detecting signals according to received light amounts thereof by central, inner-circumference-side, and outer-circumference-side light-detecting areas, receiving central, inner-circumference-side, and outer-circumference-side portions of an image of the reflected light-beam in the radial direction and allowing a signal processing unit to generate a tracking error signal by

Abstract: According to the present invention, of all beams of light reflected from the optical disc, only light in a peripheral region excluding a push-pull region is used to generate a DPD signal. In this method of signal generation that optimizes internal light-receiving surface interconnections in a photodetector, the lens error signal required for the generation of a tracking error signal in the DPP scheme is amplified at a lower amplification factor. In addition, the light reflected from the multilayered optical disc will be divided into a plurality of regions and the divided beam of light will be focused at different positions on the photodetector. When the beam is focused upon a desired layer, stray light from recording layers other than those to be subjected to information reproduction will not enter the photodetector light-receiving surfaces used for servo signals.

Abstract: A pickup device comprising an irradiation optical system including an objective lens to focus a ray bundle on a track of a recording surface of an optical recording medium to form a light spot, and a detection optical system including a photo detector to receive return light reflected from the light spot via the objective lens and perform photoelectric conversion and controls said objective lens in position according to electrical signals produced through operations on outputs of said photo detector.

Abstract: An amplifier circuit and an optical pickup device supporting multi-layered optical discs and hi-speed play mode. The amplifier circuit includes photodiodes 11 to 15; operational amplifiers 21 to 25; feedback resistors 31 to 34; resistors 41 to 45; output terminals 51 to 55; reference voltage sources 56 and 57; a reverse-bias-voltage control circuit 61; and a parasitic-capacitance detecting circuit 65. The reverse-bias-voltage control circuit 61 is connected to the cathodes of the photodiodes 11 to 15. The parasitic-capacitance detecting circuit 65 detects the parasitic capacitance of the photodiode 15. The reverse bias voltage generated in the reverse-bias-voltage control circuit 61 is adjusted according to the detection result by the parasitic-capacitance detecting circuit 65, so that the optical sensitivity of the photodiodes 11 to 14 is maintained at an appropriate value.

Abstract: A first optical receiver circuit in an optical receiver IC, which composes an optical disk device, generates a first voltage signal VS1 indicating an amount of light of a laser beam oscillated in a multimode. A second optical receiver circuit generates a second voltage signal VS2 indicating an amount of light of an optical feedback from an optical disk. A binarization circuit extracts a band component corresponding to a predetermined frequency in VS1, and binarizes the band component, thereby obtaining a digital signal. A delay element delays a phase of the digital signal by time equivalent to a phase difference between VS1 and VS2, and outputs the phase delayed signal as a timing signal. A sample hold circuit (S/H) samples and holds the VS2 in synchronization with the timing signal. Further, A LPF eliminates a band component corresponding to the frequency from an output signal of the S/H.

Abstract: There is provided a light receiver including a photodiode converting an optical signal into an electrical signal, and a plurality of amplifiers respectively having different gains, each input end of the plurality of amplifiers being connected to one end of the photodiode, and one of the plurality of amplifiers being in operating state for outputting an output signal. At least one of the plurality of amplifiers and the photodiode are connected through a diode.

Abstract: In the multi-tone demodulation (MTD) technique, even if an input bandwidth is widened to obtain a larger SNR gain, an increase in the signal to noise ration (SNR) gain cannot always be obtained due to clock jitter that increases clock noise. Also, noise is sometimes superimposed on the clock supplied to an analog to digital converter circuit (ADS) and the noise lowers the performance. Accordingly, the optical disc apparatus loosely regulates the bandwidth of a pulsed read signal; boosts the high-frequency components of a waveform of a driving signal of a laser diode; and synchronizes autonomously a driving clock of the ADC and a digital to analog converter circuit (DAC) with a clock of the pulsed read signal.

Abstract: There is provided an optical disc recording/reproducing apparatus which can reduce the chip size using the high-miniaturization process and can enhance the detection accuracy. A signal which is obtained by amplitude-adjusting a header region in a reproduced signal detected by an optical pickup (1) is digitized, and peak detection or bottom detection from the reproduced signal in each of a first section and a second section in the header region is performed by detection circuits (9) to (12), respectively. Then, amplitude data in the first section and the second section are obtained by subtracters (13) and (14) from the detected values in the respective detection circuits. A difference in amplitude between the first section and the second section in the header region is obtained by a subtracter (15) based on the amplitude data, and the amplitude difference is outputted as an off-track error signal.

Abstract: Deterioration of error rate at reproduction time is prevented even if a photodetector with a poor characteristic is included. An optical pickup unit (3) is provided with 4 photodetectors. A controller (13) obtains an error correction result of a reproduced signal, which is reproduced based on an RF signal generated while changing combination of the 4 photodetectors at startup time, and determines a combination at reproduction time in accordance with the obtained error correction result, to be given to an RF amplifier unit (10). The controller (13) is provided with a counter that counts for a fixed time period the error correction result per combination of the photodetectors, a comparator that compares a count result of the counter with a threshold set in advance, and an output controller that judges whether or not to use a combination of the photodetectors based on a comparison result of the comparator and performs change control of the combination of the photodetectors, of which there is a plurality.

Abstract: According to the present invention, whether recoding pits are larger or smaller than diffraction limit is determined. Then, a signal process suitable for processing of the recording pits larger than the diffraction limit and a signal process suitable for processing of the recording pits smaller than diffraction limit are divided to divisionally perform equalizer processing. The respective signals subjected to the divisional processing are synthesized to obtain a processed output signal. A reproduction signal with reduced impact of intersymbol interference is thus obtained.

Abstract: An optical pickup apparatus, a reproducing apparatus, a recording apparatus, and a tracking error signal generation method are provided. Four light-receiving elements receive stray light of main and sub beams reflected from, out of a plurality of recording layers of the optical disk, the one other than that for effecting recording or reproduction. The four light-receiving elements are disposed individually near every side of the four-part split light-receiving element, of which light-receiving elements are disposed between the two-part split light-receiving elements. Based on stray-light intensity detected by the four light-receiving elements, intensity distribution is calculated for tracking-error signal correction.

Abstract: An optical disk apparatus is provided which can: prevent an SNR deterioration attributable to an increase in read speed; overcome difficulty in separating a read signal and HF signal components; reduce laser noise; and maintain high reliability even during a high-speed read operation. An optical disk is irradiated with laser light pulsed by a high-frequency signal generated by a HF oscillator. The output of an optical detector which receives laser light reflected from the optical disk is converted into an electric pulse read signal using a current amplifier. The pulse read signal is converted into a temporally continuous read signal using a combination of an AD converter and a DA converter.

Abstract: An attenuation-amount adjusting circuit includes: a light irradiating unit that alternately irradiates a laser beam of a writing level and a laser beam of a readout level on an optical disk that has a groove formed by a wobble pattern and plural markers indicating physical positions in the groove; a light receiving unit that receives reflected light of the laser beam irradiated on the optical disk and converts the reflected light into a reproduction signal; and a writing-waveform attenuating unit that attenuates an amplitude level of a writing waveform corresponding to the reflected light of the laser beam of the writing level in the reproduction signal according to a position from a rising edge of the writing waveform.

Abstract: A two-dimensional digital data acquisition element includes: a pixel area having a plurality of pixels arranged in a matrix form, each of the pixels having a photoelectric conversion element to convert the reproduced light from the optical information recording medium to an electric signal; selection circuits which select the pixel; a readout circuit which reads out an electric signal of a pixel selected by the selection circuits; and a 1-bit AD converter which converts an output of the readout circuit to 1-bit digital data. A pitch ratio N between a pitch P1 of the unit data areas in the two-dimensional digital image information and a pitch P2 of the pixels in the pixel area defined as N=P1/P2 satisfies a relation A·n2/(An+1)<N<A·n2/(An?1) where A is the number of digital data in one-dimensional direction of one byte of the two-dimensional digital data and n is a natural number of at least 2.

Abstract: An optical disc apparatus comprising: an optical pickup unit having a semiconductor laser that radiates a laser light beam which is to be applied to an optical disc, a photo detector that has a plurality of light-receiving faces, which are disposed adjacent to each other, and each of which is disposed radially at an identical angle from a center of all of the plurality of light-receiving faces, and that, when the plurality of light-receiving faces receive a reflected light beam of the laser light beam applied to the optical disc, outputs photoelectric converted signals, each of which corresponds to a level of the reflected light beam at each of the plurality of light-receiving faces, a plurality of operational amplifiers that respectively output control signals for focus servo or track servo to the optical disc, based on the photoelectric converted signals, and an actuator that executes the focus servo or the track servo, based on the control signals; a driving unit that drives the actuator to execute the foc

Abstract: This invention involves irradiating an optical disk with laser light, pulse-driven by a high-frequency signal from an HF oscillator, and converting the output of a photo-detector that receives laser light reflected from the optical disk into an electronic pulse readout signal using a current amplifier. The pulse readout signal is converted into a temporally continuous readout signal by a peak hold circuit. The invention solves the problems of SNR deterioration of the readout signal and the difficulty of removing the impact of high-frequency modulation accompanying the increase in the readout speed factor in optical disk devices.

Abstract: An object of the present invention is to improve a conventional DPD method having a problem that a tracking servo becomes unstable due to a reduction in the accuracy of detecting a phase difference between short mark signals at an edge, in a case where the amplitudes of the short mark signals are very small, or where a readout signal contains large noise. To this end, the present invention provides a method for increasing the contribution ratio of long mark signals to generate a tracking error signal by causing a phase difference pulse to include information on a phase difference, and by causing the area of the pulse to be weighted according to the length of a mark/space adjacent to a concerned edge.

Abstract: Provided is an information recording/reproducing apparatus which can perform servo control with a simple circuit structure and can be manufactured at a low cost. Analog output signals from a plurality of separate portions of a photosensor which receive reflected light from an optical disk are converted into one-bit digital outputs using a plurality of ?? conversion circuits; the one-bit output signals of the plurality of ?? conversion circuits are arithmetically operated using an arithmetic circuit to generate an n-bit (n>1) servo error signal. Further, the servo error signal of the arithmetic circuit is converted into an m-bit (m>n) servo error signal by a single decimation filter.

Abstract: An optical disc driving apparatus and a land pre-pit detection method are provided for defining determination factors which have an effect on land pre-pit signal detection efficiency. The optical disc driving apparatus comprises an RF processing unit for forming a push-pull signal from an electrical signal acquired through an optical disc; and a control unit for arranging a representative value of determination factors for forming the push-pull signal and testing an error with respect to a land pre-pit (LPP) signal detected from the push-pull signal. As a result, the optical disc driving apparatus is capable of decreasing time for determining the optimal balance level and slice level, and applying the optimal balance level and slice level to the optical disc driving apparatus which operates in real time by defining representative values of each zone according to size of a balance level and a slice level.

Abstract: An optical disk drive of recording a re-writable optical disk and the method thereof. First, an optimum power is determined. A gain of a SBAD (Sub Beam Adder) signal is adjusted for generating an calibrated SBAD signal such that the calibrated SBAD signal maintains at the same level during a write power phase and a read power phase substantially. Then, the re-writable optical disk is recorded by using the optimum power. Next, a defect of the re-writable optical disk is detected according to the calibrated SBAD signal. Then, the optical disk drive will jump over the defect and prevent it from being data-recorded so as to avoid system malfunction.

Abstract: A signal processing apparatus includes sample and hold units for holding a plurality of analog photo diode signals. A signal holding controller generates control signals to the sample and hold units for holding the analog photo diode signals. Analog adjusting modules adjust the held analog photo diode signals. A multiplexer selectively couples one input end of the multiplexer to the output end of the multiplexer for outputting the adjusted analog photo diode signals. An analog to digital converter converts the adjusted analog photo diode signals into digital photo diode signals.

Abstract: A focus servo system with a focus close algorithm is disclosed. The focus close algorithm provides a bias control effort to the focus servo system when focus is closed. A method of closing focus includes positioning an optical pick-up unit at a first position away from an optical medium, moving the optical pick-up unit towards a second position by altering a focus control effort, monitoring a sum signal obtained from signals received from the optical pick-up unit, and setting the bias control effort to the focus control effort when a closure criteria is satisfied. In some embodiments, the closure criteria includes that a sum signal exceeds a threshold value. In some embodiments, the closure criteria includes that a focus error signal is below a FES threshold.

Abstract: An apparatus including a photo detector circuit, a first circuit, a second circuit and a third circuit. The photo detector circuit may be configured to generate an RF signal in response to a laser spot on a surface of an optical disc. The first circuit may be configured to generate a first digital signal in response to an AC-coupled version of the RF signal. The second circuit may be configured to generate a second digital signal in response to a DC-coupled version of the RF signal. The third circuit may be configured to generate one or more detect signals in response to the first digital signal and the second digital signal. Each of the one or more detect signals may indicate a respective condition of the surface of the optical disc.

Abstract: A light detector includes a light-receiving device that receives a light beam applied from a light source irradiating an optical recording medium with the light beam and that generates detection signals, and a power monitor circuit section that generates a power monitor signal for monitoring output power of the light source in accordance with the detection signals. The device includes split light-receiving elements. The detection signals are output from the split light-receiving elements as split detection signals. The section includes an amplifying circuit generating the power monitor signal and outputting the power monitor signal as differential signals, a fixed resistor determining a gain of the amplifying circuit, and a position-detecting signal output circuit generating position-detecting signals in accordance with the split detection signals. At least the light-receiving device, the amplifying circuit, and the fixed resistor are integrated on an identical semiconductor substrate.

Abstract: A write retry processing unit repeats a write retry operation of a write and a verify, while performing a setting change of a focus offset for recording a data on an optical storage medium in case a verify error occurs in executing the write and a verify try fails. A learning processing unit retains a sum total of the number of adding times of the successful focus offset and the number of subtracting times of the successful retry offset as a learning result at the successful time of the write retry, and a write condition changing unit changes the focus offset setting value of the default so as to be drawn near to the latest focus offset which succeeds in the retry when the absolute value of the learning result retained in the learning processing unit is equal to or more than a threshold value.

Abstract: According to a preferred embodiment of the present invention, in order to provide a tilt control method and optical disc apparatus capable of exerting control to eliminate tilt and capable of carrying out an appropriate gap servo operation, a light gathering element positioned facing a disc recordable with a signal, and capable of gathering light irradiated from a light source as near-field light at a position where a distance to the disc constitutes a first distance is made to come into contact with the disc (step 2), and tilt is controlled with the light gathering element in contact with the disc (steps 3 to 7). As a result, tilting with respect to the disc is adjusted with the SIL in contact with the disc, tilting can be eliminated in a reliable manner, and a gap servo operation can be carried out in an appropriate manner.

Abstract: Improvements to an optical recording apparatus comprising a laser light source are provided. The improvements include installing a photodiode in an optical path of at least a portion of the laser light beam from the laser light source, and connecting said photodiode to a detection circuit. The photodiode detects the laser light beam and generates a detection signal based on the detected beam. The detection circuit monitors the detection signal and generates an alarm signal if the detection signal indicates a dropout in the laser beam. The alarm signal can trigger an alarm indicator and/or cause a recording process to be halted.

Abstract: A signal processing circuit for adjusting an input signal and generating a corresponding digital output signal in an optical disk driver is provided. The signal processing circuit includes an attenuator for receiving and attenuating the input signal and then generating an attenuated output signal; a gain controllable amplifier for receiving and amplifying the input signal and then generating an amplified output signal; a control unit providing a control signal and a select signal, the control signal is directed to the attenuator and the gain controllable amplifier for enabling/disabling the attenuator and the gain controllable amplifier and for controlling their gains such that one of the attenuator and gain controllable amplifier is enabled at a time; and a waveform adjuster circuit for adjusting the amplified/attenuated output signal delivered from the gain controllable amplifier or the attenuator so as to generate the digital signal related to the input signal.

Abstract: A mark S/H circuit (66) samples, for example, a signal A generated as a photodetector (20) detects a return beam from marks of an optical disk (10), a space S/H circuit (68) samples a signal A generated through detection of a return beam from spaces, and amplifiers (70 and 72) justify amplitudes of the sampled A signals from the marks and spaces. A mark/space selector switch (74) selects alternately and combines the mark and space signals whose amplitudes have been justified. After A, B, C, and D signals A1 to D1 are subjected individually to a series of processes up to the combination process, a wobble processing circuit (80) adds them in predetermined combinations, finds differences among the added signals after justifying the amplitudes of the added signals, and thereby reproduces a wobble signal (107).

Abstract: Disclosed is an arrangement for reading an information carrier, comprising a read head for scanning the information carrier along a scanning path and thereby generating one or more electrical signals in response to a pattern recorded along the scanning path; a signal processing unit for processing the one or more electrical signals; electrical conductors for conveying the one or more electrical signals to the signal processing unit; characterized in that the arrangement further comprises controllable termination means for terminating at least one electrical conductor with a selectable impedance, the controllable termination means comprising at least two impedances and selecting means for selecting an impedance to terminate the at least one electrical conductor. The controllable termination means can select one of the at least two impedances. This makes the arrangement according to the invention capable of tuning to varying circumstances.

Abstract: A photodetector IC in an optical head device includes a four-segment photodetector (30) and a push-pull signal generator (33). The push-pull signal generator (33) generates a sum signal (A+D) of radially outer photodetector segments and a sum signal (B+C) of radially inner photodetector segments. The sum signal (B+C) is multiplied with a coefficient t entered from outside and a signal ((A+D)?t×(B+C)) is generated by a subtractor. The signal generated is output as a radial push-pull signal (R-PP). The coefficient t is a value corresponding to the ratio of the light volume of the outer rim side photodetector segments and the light volume of the inner rim side photodetector segments.

Abstract: An optical disc apparatus includes: a read unit for outputting an RF signal, which is a read signal of data recorded in an optical disc, by irradiating a laser beam to the optical disc and detecting reflected light in a photo detector; an equalize unit for performing equalize adjustment on the RF signal, which is an output from the read unit; a playback unit for generating a playback signal from the RF signal having undergone the equalize adjustment by the equalize unit and outputting the playback signal; a parameter storage unit for storing initial values of parameters used for the equalize adjustment by the equalize unit; and a parameter detection unit for detecting a value of at least one parameter at which jitter of the RF signal having undergone the equalize adjustment by the equalize unit becomes optimal during playback of the optical disc.

Abstract: Optical disk systems comprising photo detectors (1) for detecting optical disks comprising amplifiers and slicers (2-5) and delay-difference detectors (6) for detecting delay differences in sliced amplified detection signals are improved by installing delaylineless delay-difference detectors (6) comprising combinatorial-logic circuits (7,8) like inverters, ORs, NORs, ANDs, NANDs and sequential-logic circuits (11-18) like SetResetFlipFlops. Without the prior art delay lines, said delay-difference detectors (6) are of a lower complexity and low costly and can be well integrated. By introducing a first pair of sequential-logic circuits (11,12,15,16) for detecting delay differences between rising edges and a second pair of sequential-logic circuits (13,14,17,18) for detecting delay differences between falling edges, both kinds of edges are being used and the influence of time-jitter is less compared to the situation where just one kind of edge is used.

Abstract: A light-receiving amplifier circuit of the present invention includes: a first preamplifier circuit to which a light-receiving element is connected; a second preamplifier circuit which is the same type as the first preamplifier circuit and which is apart from the light-receiving element; and a differential amplifier circuit for amplifying output voltage differential between the preamplifier circuits, wherein each of the first preamplifier circuit includes an amplifier and first and second plural feedback resistors, each of which resistors has an end commonly connected to an input terminal of the amplifier; an amplification factor of the differential amplifier circuit is less than one; and the first preamplifier circuit includes an output voltage expanding circuit which is connected to (i) another end of the first feedback resistors in the first preamplifier circuit and (ii) an output terminal of the amplifier, and which circuit is for expanding an output voltage range from the amplifier and supplying the expa

Abstract: An object of the present invention is to improve a conventional DPD method having a problem that a tracking servo becomes unstable due to a reduction in the accuracy of detecting a phase difference between short mark signals at an edge, in a case where the amplitudes of the short mark signals are very small, or where a readout signal contains large noise. To this end, the present invention provides a method for increasing the contribution ratio of long mark signals to generate a tracking error signal by causing a phase difference pulse to include information on a phase difference, and by causing the area of the pulse to be weighted according to the length of a mark/space adjacent to a concerned edge.