Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Youichi Ogura

Toshihiko Takahashi

Shinichi Konishi

Kouji Okamoto

Teruhiko Izumi

Kazutoshi Aida

Shinichiro Sato

Yorikazu Takao

Hiroshi Ueda

Harumitsu Miyashita

Kohei Nakata

Hironori Deguchi

Hiroki Mouri

Yoshimasa Oda

Dai Ichiryu

Tatsushi Hiraki

Hiroaki Hayashi

Toshinori Okamoto

Seiji Matsui

Kouichi Urita

Rie Kaihara

Takamasa Sakai

Koichi Urita

Noriyuki Masunari

An instantaneous jitter information detection section detects, based on first and second digital values indicating different polarities relative to a predetermined reference value, an instantaneous gradient value corresponding to a difference value between the first and second digital values, and an instantaneous deviation value corresponding to a difference value between an intermediate value between the first and second digital values and the reference value. An information conversion section converts, based on an inversely proportional conversion table, the instantaneous gradient value to an inversely proportional value. An arithmetic section detects an instantaneous variance value by multiplying the instantaneous deviation value and the inversely proportional value together, and squaring a value obtained by the multiplication, and detects an integrated value by accumulating the instantaneous variance value. A standard deviation detection section detects a square root of a mean value of the integrated value as the absolute jitter value.

Optical disc reproduction apparatus

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.

Signal processing device

An information reproduction device according to the present invention is a device for accessing a recording medium having first address information and second address information recorded thereon. The first address information is represented by a shape formed on the recording medium in advance; and the second address information is recorded on the recording medium together with data. The information reproduction device includes a head section for accessing the recording medium to generate a reproduction signal; a first detection section for detecting the first address information from the reproduction signal; a second detection section for detecting the second address information from the reproduction signal; and a control section for, based on a detection result of either the first detection section or the second detection section which detected the address information first, controlling an access after the detection to the recording medium.

Recording medium access device

A digital signal reproducing apparatus includes an analog to digital converter for sampling and quantizing a signal read from an optical recording medium in accordance with a reproduced clock having a frequency which is one-half of a channel bit frequency and outputting an obtained digital RF signal, an offset compensation circuit for reducing an offset component in an amplitude direction from the digital RF signal, and a simplified interpolation filter for reconstructing a signal indicating a predetermined pattern recorded in the optical recording medium from the output signal of the offset compensation circuit and outputting the reconstructed signal. A control operation is performed to reduce the magnitudes of respective values shown by first phase error information on a section with the predetermined pattern and by second phase error information on a section other than the section with the predetermined pattern.

Digital signal reproducing apparatus

A waveform equalization control device includes a waveform equalizer that has a filter provided with a plurality of taps, updates the tap coefficient of each of the plurality of taps in accordance with a tap coefficient signal inputted thereto, causes the plurality of taps to respectively receive a plurality of values sampled at different time points from an input signal, performs waveform equalization with respect to the input signal, and outputs the signal after the waveform equalization, an equalization target value generation unit for determining an equalization target value, an error estimation unit for obtaining the error between the equalization target value and the signal after the waveform equalization, and a coefficient update unit for determining an amount of updating the coefficient of each of the taps of the filter of the waveform equalizer based on the error signal and on the input value to each of the taps and outputting the amount of updating the tap coefficient as the tap coefficient signal. The equalization target value generation unit obtains sign signals each showing whether the signal after the waveform equalization has a positive value or a negative value for first to fifth time points and determines a value corresponding to a total sum which is a sum of respective results of multiplying the sign signals for the first to fifth time points by &#x3b8;, &#x3b2;, &#x3b1;, &#x3b2;, and &#x3b8; (where each of &#x3b1;, &#x3b2;, and &#x3b8; is a predetermined real number) as the equalization target value.

Waveform equalization control device

After a playback RF signaldetected from an optical disc mediumis waveform-shaped, it is converted into a digital RF signalwith a sampling clockhaving a cycle twice as long as a channel clock. Thereafter, a first offset correction circuitcorrects an offset fluctuation in a high frequency band, and a digital adaptive equalizerperforms adaptive equalization, and then a second offset correction circuitcorrects an offset component that remains after the offset correction by the first offset correction circuit, thereby demodulating a digital binary signal. Therefore, even when high-speed playback is carried out and an asymmetry depending on the recording quality is large, a reduction in power consumption can be realized while maintaining high-performance playback. Consequently, it is possible to provide an optical disc playback apparatus which can realize sufficient playback performance at low power consumption.

Optical disc playback apparatus

An optical disc recording/playback apparatus is provided with a first AD converterfor shaping a push-pull signaldetected from an optical disc mediumby a light difference signal shaping circuit, and converting the signal into a digital sampling signalusing a sampling clocksynchronized with a channel frequency; a series of means for detecting wobble amplitude informationduring recording from the digital sampling signal; a series of means for detecting address polarity informationand address position information during playback; and a recording laser power control circuitfor controlling a recording laser power to a power suited for recording on the basis of the wobble amplitude information.

Optical disc recording/playback apparatus

An optical disk device is provided with a first analog-to-digital converter for converting a push-pull signal detected from an optical disc medium into a digital sampling signal according to a sampling clock in the vicinity of a channel frequency. The optical disk device also includes an address polarity information detection circuit for detecting address polarity information from the digital sampling signal, and an address position information detection circuit for detecting address position information from the digital sampling signal while maintaining continuity.

Optical disk device

When generating a sampling clock of an A/D converter for digitizing a playback signal from an optical disc, an over sampling clock generated by a PLL is used. Further, zerocross position information and reference information of a playback digital signal that is obtained by A/D conversion using the over sampling clock are converted into those synchronized with the channel bit clock by an operation cycle conversion unit, and then supplied to a PRML signal processing unit and a level judgement binarization unit.

Playback signal processing apparatus and optical disc device

In a jitter detection apparatus, a playback RF signaldetected from an optical disc mediumis subjected to waveform shaping, and thereafter, converted into a digital RF signalwith a sampling clock having a cycle twice as long as a cycle of a channel clock. Thereafter, an offset variation in a high-frequency band is corrected by an offset correction circuit, and data that are missing in the time direction are restored by a Nyquist interpolation filter. Then, positions where jitter is to be extracted are selected from an output signal of the Nyquist interpolation filter, by a jitter detection preprocessing circuit, according to the playback speed of the optical disc mediumand the arithmetic capacity of a digital signal operation circuit, whereby highly accurate jitters can be extracted by using the digital signal operation circuit

Jitter detection apparatus

An information reproduction apparatus and method according to the present invention are provided so as to solve the problem that signal quality is degraded in a normal signal part when always performing a correction of a transient in reproducing information recorded in a medium, and the sag cancellation controller () detects whether the pickup output signal (S) is normal or abnormal, and the sag cancellation part () performs a correction of a transient only during a period when the pickup output signal (S) is detected as abnormal, thereby preventing degradation of signal quality, which is caused by performing a correction of a transient on a normal signal part, and an appropriate correction of a transient can be performed on an abnormal signal part, thereby enabling a stable reproduced signal (S) to be obtained.

Information reproduction apparatus and information reproduction method

An optical disc device of the present invention obtains a reproduction quality that is independent of a mark distortion by receiving a signal that is obtained from an A/D converter for digitizing a reproduction signal of an optical disc medium and an offset correction means for performing offset correction, accurately measuring a mark distortion factor in a mark pattern having a long recording width by means of a mark distortion factor measuring means, and selecting one of output signals from a PRML signal processing means and a level judge binarization means by means of a digital data demodulation selection means by utilizing the measured mark distortion factor as a judgement criterion, to be used as a demodulation binary signal.

Optical disc device

The present invention is made to improve the conventional analog processing that is easily affected by variations in semiconductor processing. This invention provides a wobble signal processing apparatus that can reduce the circuit scale and the power consumption as well as improve the quality of signal processing. The wobble signal processing apparatus of the present invention digitally processes a part that has conventionally been processed by an analog system, and a PRML circuit is further provided to implement error detection, whereby the circuit scale and the power consumption is reduced. This improves the detection of a signal that is inputted to the wobble signal processing apparatus.

Wobble signal processing apparatus

A data demodulation process rate is varied according to a reproduction state, thereby reducing power consumption while maintaining a reading performance in a favorable state. A channel rate process data demodulation device performs a data demodulation process by employing channel bit frequency. Further, a half rate process data demodulation device performs a data demodulation process by employing frequency half as high as the channel bit frequency. These devices demodulate digital data from an optical recording medium. A process rate switching device switches a process rate at data demodulation, whereby demodulation is performed by switching between the data demodulation devices according to a quality of a reproduction signal, so as to reproduce the digital data recorded on the optical recording medium.

Optical disk reproducing device that demodulates digital data by switching between a channel bit frequency and a frequency that is half of the channel bit frequency

Growing community of inventors

Osaka, Japan

Youichi Ogura