Ricoh Company, Ltd.

Toshihiro Shigemori

Hiroshi Maegawa

Masahiko Nakayama

Haruyuki Suzuki

Kazutaka Yamamoto

Manabu Seo

Kohei Shimbo

Naohiro Kamijo

Yoichi Kubota

Isamu Moriwaki

Kiyoshi Yokomori

Yuichi Kadokawa

Haruhiko Kono

A spectral characteristic obtaining apparatus includes a detection unit detecting light quantities in plural wavelength bands from a measurement target, a storage unit storing pre-obtained spectral characteristics of the measurement target, a calculation unit calculating a primary transformation matrix from the light quantities and the pre-obtained spectral characteristics of at least one reference sample and a secondary transformation matrix from one of the pre-obtained spectral characteristics corresponding to a primary wavelength band and another one of the pre-obtained spectral characteristics corresponding to a secondary wavelength band, an estimation unit estimating the spectral characteristics of the measurement target by performing a primary estimation on the light quantities in the plural wavelength bands by using the primary transformation matrix, performing a secondary estimation on a result of the primary estimation by using the secondary transformation matrix, and compositing a result of the secondary estimation with the result of the primary estimation.

Apparatus and method for obtaining spectral characteristics

A digital phase locked loop apparatus includes an input signal time detecting device that detects a phase of an input signal with prescribed time resolution obtained by dividing a cycle of an operation clock generated by a clock generator at a prescribed time. An output clock generating device outputs output clock time data per the one cycle in accordance with frequency control data. The output clock time data has a value corresponding to a phase of a virtual output clock generated by dividing the operation clock in accordance with the time resolution. A phase difference detecting device detects a difference between phases of the input signal and the virtual output clock, and outputs a phase difference signal in accordance with the detection result. The frequency control device changes the frequency control data in accordance with the phase difference signal.

Fine clock resolution digital phase locked loop apparatus

An optical disk apparatus includes a binarizing circuit part for outputting a reference digital signal, and a digital PLL circuit part for outputting a write timing signal based on the reference digital signal, the write timing signal indicating a timing synchronizing with a digital clock signal having a predetermined frequency. The digital PLL circuit part includes an edge detection circuit part for detecting a rise edge and a fall edge of the reference digital signal in time resolution units in which a single period of a reference clock signal is divided into N (N where is no less than 2) intervals and outputting an edge detection signal for each the single period in accordance with the detection result, a digital clock data generating part for generating digital clock data in accordance with a phase difference indicated in an input phase difference signal in each the single period, and a phase difference detection circuit part for detecting a phase difference between the reference digital clock signal and the digital clock signal and outputting the phase difference signal indicating the detected phase difference.

Digital PLL circuit and optical disk apparatus having digital PLL circuit

A device for demodulating position information that is recorded as track wobbling in a record medium by a BPSK scheme includes a carrier-wave-generation circuit which derives a carrier wave from a wobbling signal obtained from the record medium, a phase-adjustment circuit which generates a phase-comparison signal having a 90&#xb0; phase difference relative to the carrier wave, a multiplier which multiplies the wobbling signal and the phase-comparison signal to supply a product signal, and a detection circuit which detects a phase error of the carrier wave introduced by the carrier-wave-generation circuit by detecting the phase error between the wobbling signal and the phase-comparison signal based on the product signal.

Demodulation circuit for demodulating wobbling signal

A recording clock generating apparatus for a data recording system includes a wobble signal sampler which samples a wobble signal, from wobble grooves of an optical disk. A first phase comparator provides a first phase-difference signal based on a difference in phase between the wobble signal and a first recording clock signal. A prepit detector detects a prepit signal from prepits of the optical disk. A second phase comparator provides a second phase-difference signal based on a difference in phase between the prepit signal and the first recording clock signal. A phase control signal generator provides a phase control signal based on a sum of the first phase-difference signal and the second phase-difference signal. A clock generator provides a second recording clock signal having a phase corrected in response to the phase control signal provided by the phase control signal generator.

Recording clock generating apparatus for a data recording system

When data recording is performed on an optical disk provided with a data recording track wobbled by a wobble signal having predetermined frequency components, a recording clock generator circuit extracts the wobble signal, generates a divided clock signal obtained by dividing the frequency of a recording clock signal at a frequency dividing rate that is set through predetermined procedures and is different from a reference frequency dividing rate, generates a phase difference signal as a result of a comparison between the phase of the wobble signal and the phase of the divided clock signal, generates a frequency control signal obtained based on the phase difference signal, and then generates a recording clock signal having a frequency controlled in accordance with the frequency control signal.

Data recording clock signal generator for generating a recording clock signal for recording data on a recordable medium

An wobble signal detection circuit that is provided on an optical disk device and can detect a wobble signal having high accuracy and stability at least when recording information on an optical disk. This wobble signal detection circuit can be applied to plural types of optical recording media. With the wobble signal detection circuit, during a period for forming a space region, a first voltage signal provided from a first light receiving element is sampled and amplified to be a target voltage, a second voltage signal provided from a second light receiving element is sampled and amplified to be the target voltage. The difference between the two amplified signals are output as the wobble signal. The first and second light receiving elements are divided from each other in the direction tangential to a recording region on the optical recording medium.

Wobble signal detection circuit and optical disk device

A first current flows through a laser diode, a second current flows through the laser diode in addition to the first current, and a third current flows through the laser diode in addition to the first and second currents. First and second switches allow the second and third currents to be provided to the laser diode and prevent the second and third currents from being provided to the laser diode. First and second pulse generators provide first and second on-off signals each having a pulse-series waveform to the first and second switches in accordance with an information code. A timing unit generates a timing signal for preventing the first and second on-off signals from being provided to the first and second switches. Output of a photo detector is sampled during a period during which the timing signal is generated, and is sampled during a period during which the first on-off signal is in an H level and the second on-off signal is in an L level. The first and second currents are adjusted depending on the thus-sampled outputs of the photo detector. The third current is adjusted so as to have the value obtained as a result of the value of the second current being multiplied by a predetermined coefficient.

Optical disk drive

A device for demodulating position information that is recorded as track wobbling in a record medium by a BPSK scheme includes a carrier-wave-generation circuit which derives a carrier wave from a wobbling signal obtained from the record medium, a phase-adjustment circuit which generates a phase-comparison signal having a 90&deg; phase difference relative to the carrier wave, a multiplier which multiplies the wobbling signal and the phase-comparison signal to supply a product signal, and a detection circuit which detects a phase error of the carrier wave introduced by the carrier-wave-generation circuit by detecting the phase error between the wobbling signal and the phase-comparison signal based on the product signal.

An ATIP decoder detects an ATIP synchronization signal from a wobble signal which was recorded on an optical disk as a wobble of pregrooves formed on the optical disk. A CD encoder performs EFM modulation on information to be recorded, inserting a subcode frame synchronization signal into the information to be recorded at a predetermined position, and outputting an EFM pattern to be recorded. The CD encoder includes an EFM outputting timing control circuit which controls a timing at which the EFM pattern is output. The EFM outputting timing control circuit performs information recording timing initialization, before the EFM pattern is actually recorded on the optical disk, in which initialization the phase between a timing at which the ATIP synchronization signal is detected from the optical disk and a timing at which the subcode frame synchronization signal is recorded on the optical disk is adjustable.

Recording timing control circuit for optical disk driving device

An optical disk drive includes a first detection unit which detects a first time signal and a first error signal, the first time signal indicating a time code of pregrooves of a recordable optical disk, the first error signal being indicative of an error of the first time signal. A second detection unit detects a second time signal and a second error signal, the second time signal indicating a time code of recorded data of the disk, the second error signal being indicative of an error of the second time signal. A time determination unit determines the first time signal as being a current time when no error of the first time signal is indicated by the first error signal, and determines the second time signal as being the current time when an error of the first time signal is indicated by the first error signal and no error of the second time signal is indicated by the second error signal. A comparator detects whether the determined current time matches with a target time. An encoder starts writing data to the disk when a coincidence of the determined current time and the target time is detected.

Optical disk drive having a time code detection device for reliably

A reference clock frequency divider feasible for a motor drive IC (Integrated Circuit), optical disk drive, hard disk drive or similar apparatus. The frequency divider is capable of setting not only integral frequency division ratios but also decimal frequency division ratios without any circuit modification.

Reference clock frequency divider

An optical disk driving apparatus for driving an optical disk which comprises annular tracks having a data area and a servo area. Center servo data pits are disposed on and along a track center. First offset servo data pits are disposed on one side of the track center. Second offset servo data pits are disposed on the other side of the track center. Each of the first and second pits is offset by a predetermined length away from the track center. The apparatus comprises a servo signal generator for detecting the pits using an optical spot and generating servo signals corresponding to the pits. The apparatus also comprises a detector for obtaining a tracking signal by subtracting the servo signals for the first and second pits. The apparatus further comprises a first comparator for comparing the servo signals for the center pits and the first pits, a second comparator for comparing the servo signals for the center pits and the second pits and a detector for detecting the misalignment of the optical spot with the track center by using outputs of the first and second comparators.

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Kanagawa, Japan

Toshihiro Shigemori