Patent application number | Description | Published |
20080219132 | OPTICAL DISK APPARATUS - 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. | 09-11-2008 |
20080284630 | READ SIGNAL PROCESSING CIRCUIT, READ SIGNAL PROCESSING METHOD, AND OPTICAL DISC DRIVE - The present invention provides a read channel and a drive capable of suppressing deterioration in performance of a PLL and a Viterbi decoder by using a DC component eliminating means capable of higher-speed operation than hitherto. The location of an edge is determined by using differential of a read signal, and a DC component is detected from the midpoint level of the edge. Detection of a pseudo-edge due to a long mark or space signal is prevented by limiting the absolute value of a maximum or minimum of a differential coefficient when the location of the edge is determined from the differential coefficient of the read signal. Internal operation of a DC component detector is controlled according to the state of the PLL and the magnitude of the DC component. | 11-20-2008 |
20090086602 | OPTICAL INFORMATION REPRODUCING METHOD, OPTICAL INFORMATION REPRODUCING APPARATUS AND OPTICAL INFORMATION RECORDING MEDIUM - Reproduction on an optical recording medium having plural information layers involves the problem of distortion occurring due to interlayer crosstalk and hence deterioration in the quality of a readout signal. At a predetermined radius, a correction coefficient for correcting the amount of fluctuation components is calculated from a readout signal with distortion due to the interlayer crosstalk, and then is stored. The stored correction coefficient is used to eliminate crosstalk components and to correct readout signal fluctuation during reproduction on a predetermined area. In this way, the original readout signal without interlayer crosstalk components can be obtained, so that good-quality reproduction characteristics can be achieved. | 04-02-2009 |
20090103418 | OPTICAL DISK MEDIUM, INFORMATION RECORDING METHOD, AND OPTICAL DISK DRIVE - Provided are an optical disk drive and a disk format necessary for the optical disk, which are capable of eliminating or reducing a problem of reduction in an effective transfer rate attributable to track jumps caused at a certain interval when performing recording and reproduction of multiple tracks in parallel by using multiple beams, and thereby achieving a high transfer rate. A block constituting a recording unit is divided into sub-blocks, and the sub-blocks are arranged in a radial direction of a disk. Meanwhile, an optical disk drive includes a means for irradiating a disk with multiple light spots, a means for pulse modulating the spots by using the same frequency and different phases, and a means for receiving light from the spots reflected by the disk by using a single photodetector, and separating the reflected light into independent lines of signals in terms of a time domain. | 04-23-2009 |
20090135699 | OFFSET COMPENSATOR AND OPTICAL DISC DRIVE USING THE SAME - The generation of a pseudo-lock is prevented in a JFB offset compensator whose use has been conventionally limited due to a tendency to generate the pseudo-lock, and performance degradation of a PLL and a Viterbi decoder is suppressed. A means for monitoring an offset of a read signal is provided independently from the JFB offset compensator. With this configuration, the generation or a possibility of the generation of the pseudo-lock can be detected to reset an integrator. In order to reduce the influence of a large sporadic offset triggering the pseudo-lock, there may also be provided a limitter for limiting the absolute value of an offset signal inputted to the integrator or a limitter for limiting the absolute value of an offset compensation signal. | 05-28-2009 |
20090136219 | Information Read Device And Read Signal Processing Circuit - An information read device enabling obtaining of a data pattern recorded on an information recording medium as a readout signal, includes an analog to digital converter for converting the readout signal to a digital signal for a predetermined clock, a phase locked loop circuit that supplies the clock used in the analog to digital converter, a first FIR filter for equalizing the digital-converted digital signal under a first equalization condition, a Viterbi decoder to decode outputs of the FIR filter into binary data, wherein the phase locked loop circuit enables detection of a cycle slip of the phase locked loop circuit, and a detector which detects the cycle slip of the phase locked loop circuit. The FIR filter returns tap coefficients of the FIR filter, and the Vitabi decoder returns a target level of a decode operation to an initial value when an out-breaking of the cycle slip occurs. | 05-28-2009 |
20090196156 | HIGH-SPEED OPTICAL DISK DRIVE - If the read speed is increased while high-frequency modulated carrier is fixed at a constant frequency, it becomes difficult to separate the read signal from the carrier by using bandwidth limitation of the analog system because the upper limit of the read signal band nears to the carrier frequency. Moreover, if the separation between them is eased by raising the carrier frequency, a problem that write-waveform controls become difficult arises. However, the carrier amplitude can be suppressed simultaneously preventing leakage to the read signal band by converting the carrier frequency into the stop-band of the adaptive equalizer by making the use of aliasing that occurs at the A/D conversion. | 08-06-2009 |
20100027390 | SIGNAL CONVERSION MODULE AND OPTICAL DISC APPARATUS USING THE SAME - The MTD has some problems. Firstly, even if an input bandwidth is widened to obtain a larger SNR gain, an increase in the SNR gain cannot always be obtained due to the clock jitter that increases clock noise. Secondly, noise is sometimes superimposed on the clock supplied to an ADC when a transmission path connecting a clock-signal source to an ADC has a certain distance or when a certain form of mounting these members is employed. The noise lowers the performance. Provided is an optical disc apparatus including: a means for regulating loosely the bandwidth of a pulsed read signal; a means for boosting high-frequency components of a waveform of a driving signal of a laser diode; and a means for synchronizing autonomously a driving clock of the ADC and a DAC with a clock of the pulsed read signal. | 02-04-2010 |
20100085858 | OPTICAL DISK APPARATUS - Analog components whose characteristics greatly differ from one another are removed as much as possible from an optical disc drive. Provided are means | 04-08-2010 |
20110080822 | OPTICAL DISC DRIVE - When a multilayered optical disc is used, the signal-to-noise ratio of a read signal is decreased as effective reflectance is extremely low due to the influence of reflection and absorption by front recording layers. Further, when a high-frequency modulation technology is used to suppress returned light noise of a laser, the erasure of recorded information is likely to occur on certain types of discs, making it difficult to simultaneously achieve the suppression of returned light noise of a laser and the prevention of the erasure of recorded information. To address the above problems, the present invention includes a section that performs a read by executing a multi-tone demodulation. The present invention also includes a section that controls the position and shape of a read light pulse to be radiated on a recording layer. | 04-07-2011 |
20120134247 | INFORMATION RECORDING METHOD, INFORMATION READING METHOD, AND OPTICAL DISC DEVICE - An optical disc device and information recording/reading method for an optical disc in which a recording layer is formed through volume recording by aligning recording tracks, which hold information, in a homogenous recording region that does not internally have a layer defining a recording position. The information recording method includes a step in which a first recording layer forming a complex recording layer is formed by forming a recording track while recording information by focusing a main beam at a predetermined depth position in the recording region, and a step in which a second recording layer forming the complex recording layer is formed by forming a recording track while recording information by focusing the main beam at a depth position that is separated from the first recording layer in a depth direction by a depth offset greater than ⅙ of a wavelength of the main beam. | 05-31-2012 |
20120213049 | READ SIGNAL EVALUATION METHOD, INFORMATION RECORDING AND READING METHOD, AND INFORMATION RECORDING AND READING APPARATUS - A read signal evaluating means for ensuring compatibility in an optical phase multilevel recording and reading system is provided. In addition, a decoding means not large in circuit scale is provided. An optical phase is modulated based on user data, and phase information thus obtained is recorded in a recording medium. Then, the phase information recorded in the recording medium is optically read, and is converted into an electric signal. The signal is subjected to adaptive equalization and to partial response most-likely decoding. A shift in a time axis direction from a target wave of a predetermined pattern is detected from the read phase information and a statistical average is calculated. Meanwhile, a value of the phase read from the predetermined pattern is extracted from the read phase information and a statistical average is calculated. | 08-23-2012 |
20140036652 | OPTICAL INFORMATION RECORDING MEDIUM, RECORDING AND REPRODUCTION METHOD, AND RECORDING AND REPRODUCTION DEVICE - In the land-groove method, wobble interference is reduced. STW modulation is used as wobble modulation for a part where wobble interference can occur, for example, a part where the configurations of both side walls of the groove are not the same and groove width modulation is unavoidable. Thereby, the amplitude of the groove width modulation can be suppressed to a quarter of that when BPSK modulation is used. | 02-06-2014 |
20140344642 | MODULATION/DEMODULATION METHOD, DEMODULATION APPARATUS, AND CODE MODULATION METHOD - Patterns that might be generated due to a burst error are prepared beforehand. These patterns are formed by shifting all “1”s in an original channel word. A list of these patterns generated as described above is retrieved in parallel with a general conversion table during demodulation. When the demodulation is interrupted due to the burst error, the result of the retrieval of the previous pattern is referred to, and when there is a hit, the error is regarded as the burst error of the original channel word, and the demodulation is continued. | 11-20-2014 |
20150043321 | CHANNEL BITWORD PROCESSOR, PRML DECODER, AND OPTICAL INFORMATION RECORDING/REPRODUCING DEVICE - It is an objective of the present invention to provide a technique, when using fixed-length run-length limit codes based on enumeration, that generates fixed-length channel bit words satisfying maximum run-length limitation using a simple configuration. A channel bit word processor according to the present invention includes an avoidance list that describes a difference between a user bit word satisfying a maximum run-length limitation of run-length limit code and a user bit word not satisfying the maximum run-length limitation. The channel bit word processor, if a user bit word does not satisfy the maximum run-length limitation, generates a channel bit word using a user bit word after the difference is added. | 02-12-2015 |