Abstract: Disclosed are a human body communication receiver and an operating method thereof, which may effectively remove low frequency noise. The human body communication receiver according to the present disclosure includes a receiving electrode, a virtual electrode, a filter circuit that is connected between the receiving electrode and the virtual electrode, and removes low frequency noise from a signal received through the receiving electrode to generate a high frequency signal, a low frequency reconstruction circuit that is connected to a rear end of the filter circuit and reconstructs a low frequency baseband signal by rectifying the high frequency signal, and an amplifying circuit that is connected to a rear end of the low frequency reconstruction circuit, and amplifies the low frequency baseband signal.

Abstract: A device includes an input for receiving an audio signal, a speaker to convert the audio signal into an audible sound, and a memory for storing remediation instructions and detection instructions. The device further includes a processor coupled to the input, the speaker, and the memory. The processor is configured to process the audio signal according to the detection instructions and the remediation instructions to modulate amplitude of the audio signal based on the remediation instructions.

Abstract: An offset correction is automatically determined and routinely updated to reduce or eliminate data retrieval errors that may be caused by low level distortion in optical disc data storage recording, re-recording and retrieval system. An offset control loop is provided for reading information from a modulated wobble signal with which the data is recorded to an optical disc data storage medium to provide detection of an offset and correction of that offset to facilitate implementation of precise timing synchronization and/or encoded information contact in the system. The offset detector measures a wobble signal and mathematically converts detected information regarding the measured wobble signal to an offset correction by integrating the wobble signal over a specific time interval and comparing the integrated value to an expected integrated value. The integration may be performed over at least one period of the sinusoidal wobble signal, and the correction added to the wobble signal.

Abstract: An offset correction is automatically determined and routinely updated to reduce or eliminate data retrieval errors that may be caused by low level distortion in optical disc data storage recording, re-recording and retrieval system. An offset control loop is provided for reading information from a modulated wobble signal with which the data is recorded to an optical disc data storage medium to provide detection of an offset and correction of that offset to facilitate implementation of precise timing synchronization and/or encoded information contact in the system. The offset detector measures a wobble signal and mathematically converts detected information regarding the measured wobble signal to an offset correction by integrating the wobble signal over a specific time interval and comparing the integrated value to an expected integrated value. The integration may be performed over at least one period of the sinusoidal wobble signal, and the correction added to the wobble signal.

Abstract: A method of operating a channel module, including: receiving a plurality of sensor signals generated based on at least one detected characteristic of a laser beam of an optical drive; performing computations based on the plurality of sensor signals; generating a computation output signal based on the computations; generating a first control signal and a second control signal; generating a first input signal based on (i) the computation output signal, (ii) the first control signal, and (iii) a first set of filter values; generating a second input signal based on (i) the second control signal, (ii) a second set of filter values, and (iii) an accumulated output signal; generating the accumulated output signal based on a sum of products generated based on the first input signal and the second input signal; and adjusting the at least one detected characteristic of the laser beam based on the accumulated output signal.

Abstract: An automated capability is provided in which an offset correction is automatically determined and routinely updated in order to reduce or otherwise eliminate data retrieval errors that may be caused by low level distortion in optical disc data storage recording, re-recording and retrieval system. The capability is implemented through an improved offset control loop for reading information from a modulated wobble signal with which the data is recorded to an optical disc data storage medium to provide detection of an offset and correction of that offset to facilitate implementation of precise timing synchronization and/or encoded information contact in the system. The offset detector measures a wobble signal and mathematically converts detected information regarding the measured wobble signal to an offset correction by integrating the wobble signal over a specific time interval and comparing the integrated value to an expected integrated value.

Abstract: A comparator includes a variable-gain amplifier circuit configured to vary an amplitude of an input signal by changing a gain in accordance with a control signal, and a comparison section configured to compare a slice level interlocked with a signal level received from the variable-gain amplifier circuit with an output signal received from the variable-gain amplifier circuit and generate an output signal in accordance with a comparison result.

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: A signal processing device, even when a steep difference in DC level is included in a signal read from a disc such as a DVD-RAM format, cuts off the DC level and pulls the read signal into an appropriate A/D input level. A steep difference in DC level between a data section and a CAPA section is absorbed by a first offset unit, and an asymmetry which occurs due to variations in the disc manufacturing stage is corrected by a second offset unit. Further, a control signal for operating the two offset units exclusively is generated by a controller, thereby controlling both offset units.

Abstract: Various embodiments of the present invention provide systems and methods for reduced latency feedback in a data processing system. For example, some embodiments provide a data processing system that includes a variable gain amplifier, a processing circuit, a data detector, and an error signal calculation circuit. The variable gain amplifier amplifies a data input signal and provides an amplified signal. The processing circuit generates a signal output corresponding to the amplified signal, and includes a conditional multiplication circuit. The conditional multiplication circuit conditionally multiplies the signal output by a gain correction signal and provides the result as an interim output. The data detector applies a data detection algorithm to the signal output and provides an ideal output. The error signal calculation circuit generates a gain correction signal based at least in part on the interim output and a derivative of the ideal output.

Abstract: The invention relates to the reading of digital optical recordings at very high density (CD, DVD, etc.). Reading is done by a PRML (“Partial Response Maximum Likelihood”) technique which uses a model of analog response to the recording of an isolated information bit. Customarily, the response model is represented by four or five signal samples having standardized levels 1 or 2. To take account of particular phenomena of super-resolution reading, the invention proposes the use of a model having 6 to 10 samples that can take 4 or 5 standardized levels. This model can result from the superposition of two simpler models having only two possible levels of samples taken from 1, 2 and 3.

Abstract: A gain control circuit to determine gain by a current ratio of mutual conductance.

Abstract: An automated capability is provided in which an offset correction is automatically determined and routinely updated in order to reduce or otherwise eliminate data retrieval errors that may be caused by low level distortion in optical disc data storage recording, re-recording and retrieval system. The capability is implemented through an improved offset control loop for reading information from a modulated wobble signal with which the data is recorded to an optical disc data storage medium to provide detection of an offset and correction of that offset to facilitate implementation of precise timing synchronization and/or encoded information contact in the system. The offset detector measures a wobble signal and mathematically converts detected information regarding the measured wobble signal to an offset correction by integrating the wobble signal over a specific time interval and comparing the integrated value to an expected integrated value.

Abstract: The gain controlling portion sets a gain of an RF amplifier to a maximum range when an activation process starts for an optical disk. The binary process condition setting portion sets an upper threshold level and a lower threshold level corresponding to 80% of upper and lower levels of the maximum range as the binary process condition for the binary process portion. A vacant part without a signal between the upper threshold level and the lower threshold level corresponds to a part of a CAPA signal. The binary signal ratio calculating portion measures a time period of a binary signal from a binary process portion that performs a binary process on the vacant part, and it calculates a binary signal ratio indicating a ratio of the time period of the binary signal to a time period corresponding to one rotation of the optical disk. The disk discriminating portion determines that the loaded optical disk is a DVD-RAM if the binary signal ratio is a value within the range of 4±1 %.

Abstract: A signal gain control method and system for use in optical disc drives to prevent undesirable saturation occurrences in circuit operations. The method includes fetching a preset reading front monitor diode signal and a preset gain controlling signal for reading; generating a front monitor diode signal by a front monitor diode signal conversion circuit; calculating a gain controlling signal based on the preset gain controlling signal for reading, the preset reading front monitor diode signal, and the front monitor diode signal by a signal processor; adjusting a gain for detection signals according to the gain controlling signal by a gain adjustment unit; and generating control signals according to the adjusted detection signals by a pre-amp module.

Abstract: An apparatus for detecting a pre-pit signal at different laser power intensities of an optical disk drive. The apparatus includes an amplifier for receiving a push-pull signal acquired from an optical disk to generate an adjusted signal, a multiplexer for receiving the push-pull signal and the adjusted signal and selecting the push-pull signal or the adjusted signal as a slicing signal for output according to a power state signal, and a slicer for receiving the slicing signal and slicing the slicing signal according to a slicing level to generate the pre-pit signal. Thus, the apparatus only needs one set of slicer to correctly slice the pre-pit signal.

Abstract: An automatic gain controller includes a voltage control gain amplifier amplifying input signals in response to a control voltage and producing output signals. A level detector detects peak and bottom levels of the output signals of the voltage control gain amplifier, and an analog-digital converter (ADC) converts the detected peak and bottom levels into digital signals. A peak detector detects a digital peak in response to a difference between the digital peak level and digital bottom level, and a voltage controller compares the digital peak and a reference voltage, and controls the control voltage.

Abstract: A signal processing apparatus for an optical disk system which apparatus has a variable gain amplifier that amplifies with a variable gain a light-detected signal obtained from an optical disk on which to perform playback processing so as to make a level of the light-detected signal coincide with a first reference level. The apparatus comprises a comparator that compares the level of the light-detected signal amplified by the variable gain amplifier with the first reference level; a gain adjuster that generates and supplies a control signal to adjust the variable gain according to a result of the comparing to the variable gain amplifier; and a gain adjustment controller that, when the level of the light-detected signal amplified is within a level range including the first reference level, controls a level of the control signal of the gain adjuster to be held at its preceding value.

Abstract: An optical disk apparatus has a highly accurate trial writing function corresponding to a PRML system and copes with a bad jitter of a 2Tw mark in order to realize an optical disk, the recording/reproduction of which is enabled in both a DVD and a Blu-ray Disc by a drive. After a reproducing signal is A/D-converted, error pulse generation is enabled corresponding to the PRML by detecting an edge signal level, and an error pulse is generated when the level exceeds a threshold. At the same time, trial writing that corresponds to the difference in the jitter of the 2Tw mark and a mark of 3Tw or more is enabled by providing multiple error pulse thresholds.

Abstract: An optical information reproduction apparatus for reproducing a recording signal by irradiating a light beam onto a recording surface of an optical information recording medium having at least two information recording layers and by receiving reflected light of the light beam is provided. The optical information reproduction apparatus includes an extraction section for extracting an envelope signal of a reproduction signal when the reproduction signal reproduced by focusing the light beam onto one information recording layer in the plural information recording layers has been modulated by interlayer crosstalk from another information recording layer; and a distortion correction section for correcting the distortion of the target reproduction signal caused by the interlayer crosstalk by gain-adjusting the reproduction signal containing DC components so that the envelope signal becomes constant.

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 push-pull signal is detected from light reflected from a disk-shaped storage medium on which wobbling grooves are formed as recording tracks and address information is recorded by forming pre-pits on lands between adjacent grooves. A fundamental amplitude variation signal indicating the fundamental amplitude variation of the push-pull signal is acquired, and a reference voltage is generated by adding an offset voltage to the fundamental amplitude variation signal. Pre-pits are detected by comparing the push-pull signal with the reference voltage. Because the reference voltage is produced on the basis of the fundamental amplitude variation signal indicating the variation components of the push-pull signal due to the wobbling of grooves and noise, the variation components due to the wobbling and noise are reflected in the reference voltage. Furthermore, the variation components of the push-pull signal corresponding to the pre-pits are also reflected to a properly small extent in the reference voltage.

Abstract: The present invention discloses a mixed mode circuit for data slice with auto calibration and method thereof, which comprises a data slicer for converting an analog signal into a digital signal; a set of current pump for supplying a variable power supply; a microprocessor for controlling and adjusting the set of current pump; a digital sum value counter for performing an addition or a subtraction operation according to the result outputted by the data slicer; a digital signal processor for reading the internal values of the digital sum value counter and calculating the average of these internal values to obtain a parameter value. With the aforementioned structure, the invention integrates the mixed mode data slicer of analog and digital circuits so as to adopt the merits and eliminate the drawbacks of the pure analog and digital data slicer and thus achieves the objective of reading data from an optical disk better and more accurately.

Abstract: A method for dynamically adjusting a header region RF gain of a variable gain amplifier while accessing header regions of a DVD-RAM disc, and apparatus thereof. The method includes the following steps: irradiating a light spot on the DVD-RAM disc with a pickup head; detecting a 4T peak-to-peak level of a RF signal generated by the variable gain amplifier while the light spot is moving within a VFO1 column of a header region of the DVD-RAM disc; comparing the 4T peak-to-peak level with a target level; adjusting a header region RF gain of the variable gain amplifier according to a result of the comparing step.

Abstract: A method and apparatus for signal equalization in a light storage system is disclosed. The method includes observing run length of an RF signal read from the optical disc; classifying run lengths into sets; calculating the mean of certain run lengths; comparing the values with expected values of said run lengths to generate an error value; and adjusting equalizing parameters of boost and frequency if the error value lies outside an expected range.

Abstract: An optical information recording/reproducing apparatus is provided that condenses a light flux from a light source on an optical recording medium and effects recording/reproduction and comprises a light source; an objective lens; a spherical aberration generating mechanism; a sensor for receiving light reflected by an optical recording medium and converting the light into an electric signal; an equalization filter for effecting waveform equalization of an output from the sensor in accordance with a predetermined partial response characteristic; a quality evaluating circuit for measuring reproduction quality of an output signal from the equalization filter; and an adaptive equalization circuit for sequentially updating a coefficient for the equalization filter, wherein while the update of the coefficient for the equalization filter by the adaptive equalization circuit is stopped, the spherical aberration generating mechanism is driven on the basis of the reproduction quality measured by the quality evaluating

Abstract: An error pulse is generated from a PRML circuit, and reproduction compatibility with a conventional apparatus is established. After a reproducing signal output from an optical head is equalized by an analog equalizer, sampled by an A/D converter at every clock, and digitally equalized by a FIR filter, the signal is binarized by a PRNL decoder. On the other hand, with regard to an error pulse, a level at an edge point is detected from an output signal of the A/D converter by an edge level detector, and the level at the edge point and an error pulse detection threshold are compared by an error pulse generator, and the error pulse is generated. Even when an optical apparatus having a trial writing function using conventional error pulse is provided with a PRML reproducing system for enabling high speed, the optical apparatus can execute trial writing using the error pulse as it is.

Abstract: The present invention has an object to stably reproduce wobble signals of all disks of CD-R/RW, DVD-R/RW and DVD-RAM by one wobble signal reproducing circuit. In the wobble signal reproducing circuit, an AGC (AUTOMATIC GAIN CONTROL) circuit for equating a push-pull circuit output of a wide range and an RF amplitude of an optical detector output of two systems obtained by push-pull, and an AGC (AUTOMATIC GAIN CONTROL) circuit for making a wobble amplitude uniform are provided with a function to hold a gain or to change over a response time constant, and at the time of reproduction of the DVD-R/RW, a land pre-pit region is detected by the push-pull output to hold AGC (AUTOMATIC GAIN CONTROL) or change over a response time constant. Besides, in an address information recording region (PID region) at the time of reproduction of the DVD-RAM, the AGC (AUTOMATIC GAIN CONTROL) is held or the response time constant is changed over.

Abstract: A method for processing signals in a disk drive is provided. In the provided method, an RF signal is read at a predetermined highest reading speed, whose amplitude is adjusted with a gain. Then the level of the RF signal is adjusted by an equalizer with a predetermined parameter module. The RF signal is output if it could be read correctly. If failing to be read correctly, the amplitude of the RF signal to be read is checked. If the amplitude of the RF signal is not within a predetermined range, the gain is adjusted and then the step of reading the RF signal is re-proceeded and the procedures thereof are repeated. A further parameter module is applied by the equalizer if the amplitude of the RF signal is within the predetermined range. The procedures of the provided method are repeated after the reading speed of the disk drive is reduced if all of the parameter modules are applied.

Abstract: A two-stage amplifier of a first-stage amplifier 21 and second-stage amplifiers 22 and 23 is provided. A writing mode and reproducing modes are switched in the first-stage amplifier 21 by switching a parallel circuit of a feedback capacitor Cf1w and a feedback resistor Rf1w and a parallel circuit of a feedback capacitor Cf1r and a feedback resistor Rf1r. The second-stage amplifier 23 is provided with feedback resistors Rf22 and Rf23 that are connected to each other in parallel. The feedback resistor Rf23 is connected in the feedback loop by a switch transistor QSW only when reproducing a high-reflective disk. This enables an amplifier gain to be suitably set for each of writing, low-reflective disk reproducing, and high-reflective disk reproducing. As a result, desirable reproducing characteristics can be obtained for the low-reflective disk while accommodating high-speed writing with a large laser power.

Abstract: An optical signal converter and a method or controlling an amplification gain according to a rotating speed of an optical disc. An optical signal detector detects an optical signal reflected from an optical disc in a reproduction mode and converts the detected optical signal into an electrical signal. A gain control signal generator generates a gain control signal when a voltage level of a driving signal used to drive the optical disc exceeds a maximum output voltage of the optical signal converter. A gain switcher selects an amplification gain of the optical signal converter in response to the gain control signal and an external control signal. A signal amplifier amplifies a signal output from the optical signal detector in response to an output signal of the gain switcher.

Abstract: An optical disc system comprises a gain offset unit for giving a gain and an offset to an inputted reproduction signal, an A/D converter, a peak detector, a bottom detector, an amplitude detector for calculating a signal, an offset detector for calculating a signal offset, a dropout detector for detecting a dropout in the input signal, and a controller for performing gain control and offset control of the gain offset unit, the controller being able to hold the control operation or switch the control speed by a hold signal that is supplied from the outside, wherein a defect in a recording medium is detected to hold the gain control and offset control or change the control response speed, whereby the signal amplitude and offset at the input of the A/D converter are always kept constant.

Abstract: Disclosed is a PLL circuit having a voltage-controlled oscillator, to which a difference voltage across non-inverting and inverting input terminals is input as a control voltage, for oscillating at a frequency in accordance with the control voltage; a phase comparator for comparing the phase of an output signal obtained by frequency-dividing the output of the voltage-controlled oscillator by a frequency-divider, with the phase of an input signal and outputting the result of this phase comparison; first and second loop filters connected at output terminals thereof to the non-inverting and inverting input terminals, respectively, of the voltage-controlled oscillator; and a charge pump, which is responsive to receipt of an UP signal supplied from the phase comparator, for supplying a first charging current from a PMOS transistor to a capacitor of the first loop filter and supplying a first discharge current from an NMOS transistor to a capacitor of the second loop filter, and which is responsive to receipt of a

Abstract: An electronic circuit is provided which can autonomously handle an input current (Ii) having a relatively wide dynamic range without being overdriven. The electronic circuit comprises an amplifier stage (AMPST) having an input (IP) for receiving the input current (Ii) and an output (OP) for supplying an output current (Io), such that, during operation, the strength of the output current (Io) increases in response to an increasing strength of the input current (Ii) as long as the strength of the input current (Ii) has not exceeded an input reference level. The strength of the output current (Io) is kept approximately constant when the strength of the input current (Ii) has exceeded the input reference level but has not exceeded a further input reference level. The strength of the output current (Io) decreases in response to an increasing strength of the input current (Ii) when the strength of the input current (Ii) has exceeded the further input reference level.

Abstract: The invention refers to a device and a method for scanning an optical data carrier by means of a main scanning beam being reflected by the data carrier and being detected by means of a photodetector, the data carrier having first and second layers to be scanned, the second layer being scanned through the first layer, light passing the first layer being shaded dependent on local properties of the first layer. An object of the invention is to propose a device having increased performance even for use with multi layer disks having a layer causing light fluctuations on a layer to be scanned, as well as a respective method. According to the invention such device is provided with means for keeping an output signal of the photodetector independent of variations of shading.

Abstract: A two-stage amplifier of a first-stage amplifier 21 and second-stage amplifiers 22 and 23 is provided. A writing mode and reproducing modes are switched in the first-stage amplifier 21 by switching a parallel circuit of a feedback capacitor Cf1w and a feedback resistor Rf1w and a parallel circuit of a feedback capacitor Cf1r and a feedback resistor Rf1r. The second-stage amplifier 23 is provided with feedback resistors Rf22 and Rf23 that are connected to each other in parallel. The feedback resistor Rf23 is connected in the feedback loop by a switch transistor QSW only when reproducing a high-reflective disk. This enables an amplifier gain to be suitably set for each of writing, low-reflective disk reproducing, and high-reflective disk reproducing. As a result, desirable reproducing characteristics can be obtained for the low-reflective disk while accommodating high-speed writing with a large laser power.

Abstract: A ROM 51 stores a plurality of volume set values and a plurality of level change rates corresponding to each other and an IC 5 accepts a volume set value specified by a user when carrying out volume setting. Moreover, it is decided whether a reproducing object is a CD or a DVD depending on a decision signal output from a loader section 1. A level change rate corresponding to the volume set value is output to an IC 2 if the reproducing object is the DVD, and the level change rate corresponding to the volume set value is adjusted at a predetermined adjusting rate and the level change rate thus adjusted is output to the IC 2 if the reproducing object is the CD. The IC 2 changes the level of an analog signal indicative of a voice input from the loader section 1 at the level change rate and outputs the signal to an amplifying circuit 3.

Abstract: A recording system, such as a magnetic or optical recording system, sets input attenuation level setting and variable gain amplifier (VGA) operating region during zero gain start (ZGS) by sharing the ZGS adjustment between attenuator settings and VGS gain setting. Further adjustment is made to attenuator settings and VGS gain setting for each subsequent servo or read sector event. The input attenuation level setting and variable gain amplifier (VGA) operating region are set so as to minimize effects of gain error due to incorrect attenuator setting, and subsequently operate the VGA near the center of its range where the non-linear effects are minimal.

Abstract: The signal processor includes an analog filter, an analog-to-digital (A-D) converter, an adaptive equalization filter, a quality value calculating circuit, and a control circuit. The analog filter removes high-frequency noises of a played-back signal from a recording medium and amplifies a specific frequency band of the played-back signal. The A-D converter converts the played-back signal from the analog filter into a digital signal. The adaptive equalization filter performs waveform equalization of the played-back signal from the A-D converter while adjusting a tap coefficient of the adaptive equalization filter so as to reduce a difference between an output of the adaptive equalization filter and a target value. The quality value calculating circuit calculates a quality value based on the difference between the output of the adaptive equalization filter and the target value.

Abstract: A recordable or rewritable optical disk device capable of reproducing a wobble signal accurately at a high S/N ratio to thereby get address information even at a time of high-speed recording is disclosed. An optical disk is formed with wobbled guide tracks, and the light reflected from the optical disk is picked up by an optical pickup unit, which supplies corresponding electric signal to a wobble signal reproducing section. In the wobble signal reproducing section, at a time of recording, the input signal is sampled not only during a period of reproducing power and also during a period of recording power, and the two sampled signals are added to reproduce a wobble signal. The sampling during the period of recording power may be carried out within a period where the quantity of reflected light is in a stable condition after a pit is formed on the optical disk.

Abstract: Correction for harmonic disturbances on rotating storage media in a phase-locked loop. The effects of harmonic disturbances in a phase-locked loop are reduced by employing harmonic correction. Harmonic correction may be present in the loop at all times, or may be switched in once the loop has achieved phase lock. Disturbance within the loop bandwidth is corrected using additional integrating pole or a bump (resonant) filter. Disturbance outside the loop bandwidth is corrected using low pass or a notch (anti-resonant) filter. Alternately, a canceling signal may be generated and added as a feedforward signal. A repetitive control scheme uses a filtered version of the residual errors on previous media rotations as a feedforward signal to cancel harmonic effects.

Abstract: A wobble detection circuit detects a signal by a common photodetector (light receiving) element from several kinds of media having different pre-formats. Further, the wobble detection circuit changes a gain for amplifying the signal in a wobble signal detection process depending on the pre-format of a reproducing or recording medium to obtain a wobble signal.

Abstract: A method and apparatus in an optical disk system employing a decision feedback equalization (DFE) technique to provide a boosted signal resolution at a data slicer input while minimizing noise. In one embodiment, an optical equalizer includes a feed forward equalizer (FFE) that equalizes the signal from the optical disk and provides an equalized signal and a feedback equalizer (FBE) that generates a feedback signal. The feedback signal is subtracted from the equalized signal to provide a signal having increased resolution and low noise, which is then applied to a data slicer. In one embodiment, the boost provided by the FFE is lower than in conventional equalizers to minimize noise. As the boost of the FFE is reduced, the number of taps in the FBE is increased to provide optimized system performance.

Abstract: An automatic gain controller (AGC) for preventing peaking in an optical disc reproducing system includes a capacitor for being charged to a voltage corresponding to a control current as a control voltage; an amplifier for inputting the optical disc reproducing signal as an input signal, amplifying the input signal by a gain corresponding to the control voltage, and generating the amplified input signal as the output signal; a peak detector for detecting a peak voltage in the output signal; a gm amplifier for converting a peak voltage detected by the peak detector into current and generating the converted current as the control current; and a peaking controller for preventing the capacitor from being charged by the control current in a defect section in the input signal, in response to a peaking control signal, and for maintaining a control voltage in the defect section to be the same as the prior to the defect section.

Abstract: A reproduction signal evaluation method of this invention includes the step of obtaining a reproduction signal from an information recording medium on which digital information is recorded with record marks having different sizes, the step of obtaining the amplitude of a first reproduction signal, of the signals contained in the reproduction signal, which reflects digital information recorded with a record mark having the maximum size, the step of obtaining the amplitude of a second reproduction signal, of the signals contained in the reproduction signal, which reflects digital information recorded with a record mark having the second smallest size, the step of obtaining an evaluation value from the ratio of the amplitudes of the first and second reproduction signals, and the step of evaluating a characteristic of the reproduction signal on the basis of the evaluation value.

Abstract: The present invention has an object to stably reproduce wobble signals of all disks of CD-R/RW, DVD-R/RW and DVD-RAM by one wobble signal reproducing circuit. In the wobble signal reproducing circuit, an AGC (AUTOMATIC GAIN CONTROL) circuit for equating a push-pull circuit output of a wide range and an RF amplitude of an optical detector output of two systems obtained by push-pull, and an AGC circuit for making a wobble amplitude uniform are provided with a function to hold a gain or to change over a response time constant, and an address information recording region (PID region) at the time of reproduction, the AGC (AUTOMATIC GAIN CONTROL) is held or the response time constant is changed over.

Abstract: In the context of mirror modulation (56, 90, 104) extraction during track seek or jump modes of an optical disc reading device (12), such as a DVD ROM, a mirror averaged level (i.e. the dc level (52) of the RF envelope (34)) is held so that the mirror modulation (90) is seen as a swing below a set mirror rebias level (86) at an output of a mirror amplifier (72), as shown in FIG. 3. With the holding of the dc level (52) by a ground-referred capacitor (302) during seek operation of the device (12), a first input (nin) to the mirror amplifier varies with the mirror modulation, whereas a second input (pin) to the mirror amplifier (72) does not vary. This phenomenon enables the top level of a RFRP signal (82) to be defined by the mirror rebias level (86) and the mirror component swing (during seek operation) to be optimized and always to occur below the mirror rebias level (86).

Abstract: A prepit detecting apparatus which uses an optical recording medium having information recording tracks on which information is recorded and guide tracks each of which guides a light beam to the information recording track and on which prepits for saving pre-information are formed such that the light beam is applied to the information track of the optical recording medium, the prepit detecting apparatus comprising: light receiving means divided into a first divided light receiving portion and a second divided light receiving portion divided along an optically parallel division line in a direction of tangent of the information tracks and arranged to receive reflected light of the light beam with which the optical recording medium has been irradiated; and a difference calculator for calculating the difference between a first read signal output from the first divided light receiving portion and a second read signal output from the second divided light receiving portion so that the prepit is detected in response

Abstract: The invention refers to a device and a method for scanning an optical data carrier (1) by means of a main scanning beam (3) being reflected by the data carrier (1) and being detected by means of a photodetector (10), the data carrier (1) having first and second layers (11,12) to be scanned, the second layer (12) being scanned through the first layer (11), light passing the first layer (11) being shaded dependent on local properties of the first layer (11). An object of the invention is to propose a device having increased performance even for use with multi layer disks (1) having a layer (11) causing light fluctuations on a layer (12) to be scanned, as well as a respective method. According to the invention such device is provided with means (2,7,17) for keeping an output signal (D) of the photodetector (10) independent of variations of shading.

Abstract: A laser diode applies a laser beam through a grating, a beam splitter, and an objective to a compact disc. A laser beam reflected by the compact disc is applied through the objective and the beam splitter to a photodiode. The objective has a large numerical aperture of 0.6 in order to be able of play back a digital video disc that has a thin substrate and contains information recorded at a high density. To prevent the photodiode from suffering aberrations caused due to the large numerical aperture of the objective, the photodiode has a relatively small photodetector unit having a normalized detector size ranging from 3 &mgr;m to 16 &mgr;m, for detecting only returning light up to a numerical aperture of 0.3 and not detecting light of greater numerical aperture values.