Fujitsu Corporation

Texas Instruments Japan Limited

Fujitsu Limited & Texas Instruments Japan

Kazuyuki Tamanoi

Michio Matsuura

Akira Minami

Shigeyoshi Tanaka

Hiromichi Kuwano

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

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.

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Hayami-gun, Japan

Kazuyuki Tamanoi