Fujitsu Corporation

Texas Instruments Japan Limited

Fujitsu Limited & Texas Instruments Japan

Shigeyoshi Tanaka

Akira Minami

Michio Matsuura

Hiromichi Kuwano

Kazuyuki Tamanoi

Shigenori Yanagi

Toru Ikeda

Masaaki Iwasaki

Takashi Masaki

Masaharu Moritsugu

Kenichi Hamada

Satoshi Furuta

Hideki Nishimoto

Akira Nanba

Masateru Sasaki

Toshitaka Iwamoto

Shuko Saito

Shigeru Kagawa

Soichi Shimura

Eiji Kaneko

A power supply control device is provided with a first power supply input terminal to which a power supply is provided and a second power supply input terminal to which a power supply is provided. A power supply input detection unit detects an instance when the input of the second power supply input terminal is above a predetermined value and then a switch unit cuts off power supplied from the first power supply input terminal and activates power supply from the second power supply input terminal when the input from the second power supply input terminal is above a predetermined value according to the power supply input detection unit. A power supply processor processes a power supply supplied by way of the first or second power supply input terminal.

Method for providing priority to an ac adaptor if the input to the ac adaptor is above a predetermined value even if the power supply via an interface is present

A servo control apparatus of an optical pickup in which an offset and a gain can be adjustable for each servo control apparatus, and influences caused by changes in environmental conditions and changes with time are reduced without a decrease in operational speed, and increase in size and an increase in cost is disclosed. The servo control apparatus includes a nonvolatile memory for storing compensatory values which correspond to differences of servo characteristics of each servo apparatus and which are measured with the assistance of external measurement instruments, and a compensation portion for compensating an optical pick-up servo signal according to the compensatory values stored in the nonvolatile memory.

Optical pickup servo control apparatus with stored compensatory values

A battery pack is detachably provided for a drive main body. When carrying, an interface card and a connector cable are detachably supported and fixed to the drive main body by a holder member, thereby packaging. A power source is supplied from an upper apparatus to a control IC circuit unit of a device via the interface card. Only when both of the power supply from the upper apparatus and the power supply from an external power source unit are detected, the power source from the external power source unit is supplied to a device circuit unit, thereby making the device circuit unit operative.

Storage apparatus

A frequency synthesizer generates, through setting of a frequency control value, a reference clock having a frequency necessary to read data from a medium. When reading data from an arbitrary position on the medium, a setting control unit sets in the frequency synthesizer a frequency control value corresponding to the zone position, thereby allowing the frequency synthesizer to control a reference clock frequency, and sets in a single or a plurality of processing units other than the frequency synthesizer a predetermined control value corresponding to the read position on the medium. A settling wait processing unit calculates a settling time T1 required for a frequency of the frequency synthesizer to become stable and a setting processing time T2 necessary for the setting control of the other processing unit, and defines as a wait time Tw a difference (T1-T2) between the settling time T1 and the setting processing time T2, during which wait time Tw a migration to the subsequent processing is kept waiting.

Storage apparatus using variable read clock frequencies for reading ZCAV

There is provided an optical storage device that can position a lens carriage and objective lens even when position sensors for the lens carriage and objective lens are excluded in an effort to make an optical disk unit thinner. In the optical storage device, immediately after an optical disk is loaded in a main body, the cutoff frequency of a filter lying on a path of a reproduction signal is temporarily changed to a lower frequency. A spacing of sectors of the optical disk is detected using a signal sent from the filter. A type of an optical storage medium and a position of a current reproduction track are detected on the basis of the detected sector spacing and data stored in a memory.

Optical storage device made thinner by substituting electrical means for

A positioning control system for performing recording/reproducing operations by irradiating an optical beam to a predetermined position on an optical recording medium, includes a photo-detector and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between the detection currents. Preferably, the servo-error signal generating circuit includes at least one division circuit having two pairs of transistors, two emitters in each pair of transistors being connected together into a common emitter, bias voltages of direct current type being applied to the respective bases of transistors on one side, the respective collectors of the transistors on one side being connected to a common connecting portion via resistors, the common connecting portion being connected to a power supply, the respective bases of transistors on the other side being connected together into a common base; and an integrating capacitor which is connected to the common base of transistors on the other side, and which integrates a difference between the current flowing through the common connecting portion and the reference current, to apply the thus integrated difference to the common base of transistors on the other side.

Positioning control system including a servo-error signal generating

A positioning control system for performing recording/reproducing operations by irradiating an optical beam to a predetermined position on an optical recording medium, e.g., magneto-optical disk. The control system includes a photo-detector constituted by at least two-divisional units, and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between the detection currents. Preferably, the servo-error signal generating circuit includes at least one division circuit that has two pairs of transistors, two emitters in each pair of transistors being connected together into a common emitter, bias voltages of a direct current type being applied to the respective bases of transistors on one side, and the respective collectors of the transistors on one side being connected to a common connecting portion via resistors. The common connecting portion is connected to a power supply, and the respective bases of transistors on the other side are connected together into a common base. An integrating capacitor which integrates a difference between the current flowing through the common connecting portion and the reference current, is connected to the common base of the transistors on the other side.

Positioning control system which generates a servo-error signal in

A positioning control system for performing recording/reproducing operations by irradiating an optical beam on a predetermined position on an optically recording medium includes a photo-detector constituted by at least two-divisional units and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between detection currents measured at the collectors of selected transistors in two pairs of transistors.

Positioning control system having an optical beam and a servo-error

A positioning control system for performing recording/reproducing operations by irradiating an optical beam to predertermined position on an optically recording medium, e.g., magneto-optical disk, includes a photo-detector constituted by at least two-divisional units; and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between the detection currents. Preferably, servo-error signal generating circuit includes at least one division circuit that has two pairs of transistors, two emitters in each pair of transistors being connected together into a common emitter, bias voltages of direct current type being applied to the respective bases of transistors on one side, the respective collectors of the transistors on one side being connected to a common connecting portion via resistors, the common connecting portion being connected to a power supply, the respective bases of transistors on the other side being connected together into a common base; and an integrating capacitor which is connected to the common base of transistors on the other side, and which integrates a difference between the current flowing through the common connecting portion and the reference current, to apply the thus integrated difference to the common base of transistors on the other side. Further, preferably, the photo-detector is connected to the common emitters in the respective pairs of transistors, so that the detection currents can flow through the common emitters.

Positioning control system utilizing optical beam having servo-error

Disclosed is an optical disk apparatus having a zero-cross signal generating unit for differentiating a reproduced signal read from an optical disk and outputting a zero-cross signal when the differentiated signal crosses the zero level, and a gate signal generating unit for generating a gate signal using the reproduced signal, wherein a data pulse is outputted when the zero-cross signal is generated while the gate signal is being produced. A clamping circuit clamps the peak of a reproduced signal from an optical disk, an amplitude comparator compares the amplitude of a clamped signal, which is outputted by the clamping circuit, with a reference voltage, and an AGC control unit controls the gain of a variable-gain amplifier by generating a control voltage signal in dependence upon an amplitude difference. The gate signal generating unit generates the gate signal upon comparing the clamped signal outputted by the clamping circuit with a prescribed signal level. A data-pulse output unit outputs the data pulse when the zero-cross signal of the differentiated reproduced signal is generated while the gate signal is being produced.

Disk reproducing circuit with automatic gain control

A positioning control system for performing recording/reproducing operations by irradiating an optical beam to predetermined position on an optically recording medium, e,g., magneto-optical disk, includes a photo-detector constituted by at least two-divisional units; and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between the detection currents. Preferably, servo-error signal generating circuit includes at least one division circuit that has two pairs of transistors, two emitters in each pair of transistors being connected together into a common emitter, bias voltages of direct current type being applied to the respective bases of transistors on one side, the respective collectors of the transistors on one side being connected to a common connecting portion via resistors, the common connecting portion being connected to a power supply, the respective bases of transistors on the other side being connected together into a common base; and an integrating capacitor which is connected to the common base of transistors on the other side, and which integrates a difference between the current flowing through the common connecting portion and the reference current, to apply the thus integrated difference to the common base of transistors on the other side. Further, preferably, the photo-detector is connected to the common emitters in the respective pairs of transistors, so that the detection currents can flow through the common emitters.

Positioning control system utilizing optical beam

A laser diode having a cathode connected to the ground side of a positive power source and an anode connected to the plus voltage side of the power source through a control circuit. A maximum current to drive the laser diode is supplied to the laser diode by a disgorging type constant current source. In a reading mode operated at a frequency one or more digit higher than a frequency for writing data, a differential current between the write current and a read current is sucked from the disgorging type constant current source by a sucking type constant current source, thereby allowing the read current to flow into the diode. In a writing mode, a current switch connects the sucking type current source according to write data. The disgorging type current source and the sucking type current source are connected to a photodiode by a current switch. An APC responds to the photodiode which detects a read power, thereby reducing a laser fluctuation created from temperature change.

Control apparatus of laser diode

A position control system for an information storage system, for example, an optical disc system, includes a stepping motor for moving a read-write head and a DC motor for moving a beam reflecting unit, such as an object lens mounted on the head. The position control system drives the stepping motor to compensate a positional error of the beam reflecting unit in a tracking mode after a seek without disturbing the movement of the beam reflecting unit. The position control system includes a master control unit operatively connected to a host controller, a stepping motor control unit, and a track servo control unit. The master control unit activates the stepping motor control unit for a seek operation upon receipt of a seek command from the host controller. The stepping motor control unit drives the stepping motor with a large drive current until the head moved by the stepping motor reaches a position adjacent to a target track on the recording medium. In a tracking operation, the track servo control unit drives the DC motor in response to a positional error of the head at the target track to finely control a position of the head at the target track. The stepping motor control unit drives the stepping motor by a predetermined rotation angle with a small drive circuit to compensate a position of the access end when the position of the beam reflecting unit exceeds a limit of a controllable range of the beam reflecting unit.

Position control system for information storage system

An optical disk access system capable of varying the focus position of a beam spot illuminating the optical disk. The focus position of the beam spot is varied in accordance with a mode of operation of the optical disk system. The various focus positions are automatically selected by the optical disk access system by intentionally vibrating the beam spot in a radial direction of the optical disk and detecting the amount of light reflected from the optical disk while varying a signal that changes the focus position of the beam spot. The optical disk system automatically selects a value of the signal determining the focus position of the beam spot that corresponds to maximum values derived from the light reflected from the optical disk.

Optical disk access system

A track access control system for a disk storage system having an eccentricity correction unit. The eccentricity correction unit includes an eccentricity detecting unit, an eccentricity data storage unit and an eccentricity compensation unit. The eccentricity data storage unit includes a memory, an address generating circuit, a filter and a comparator. The comparator and the filter function as delta modulation means to provide digital eccentricity data to be stored in the memory. The filter also outputs analog eccentricity data to be used for compensation of the eccentricity.

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Kawasaki, Japan

Shigeyoshi Tanaka