| 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 |
