Fujitsu Corporation

Hidekazu Shibasaki

Hiroaki Ueno

Ken Yakuwa

A signal reproducing circuit includes first power supply lines having different potentials, a magneto-resistive effect head having one end thereof coupled to the first power supply line, for reproducing data recorded on a magnetic recording medium in a read operation, and a first constant current source coupled between another end of the magneto-resistive effect head and the second power supply line, for supplying the magneto-resistive effect head with a sense current in the read operaion. Also included are first and second transistors having collectors thereof coupled to the first power supply line, respectively, and responsive to voltage signals obtained from the one end and the other end of the magneto-resistive effect head. Second and third constant current sources are coupled between each emitter of the first and the second transistors and the second power supply line, respectively, for supplying the first and the second transistors with a first predetermined constant current, respectively, in the read operation. Fourth and fifth constant current sources are provided between each emitter of the first and the second transistors, respectively, and the second power supply line for increasing the emiter curents of the first and the second transistors to a second predetermined constant current during a predetermined period in a transition from a write state to a read state.

Signal reproducing circuit for magneto-resistive head including control

A signal reproducing circuit for a magneto-resistive effect head includes a constant current source for supplying a sense current to an MR head in a read state, first constant current sources for supplying first constant currents to a pair of reproduction transistors in the read state, and a capacitor connected between the emitters of the transistors. Furthermore, second constant current sources for supplying second constant currents are connected in parallel with the first constant current sources. Control is given so that when switching an idle state to the read state is commanded, the second constant current sources remain on for a given period of time. Owing to this circuitry, a transient period during which the idle state is switched to the read state or a transient period during which heads are switched in the read state can be shortened to a great extent. Consequently, superposition of an unwanted offset component on a reproduced signal can be suppressed, and a loss in data-handling capacity can be minimized.

Signal reproducing circuit adapted to head utilizing magneto-resistive

A signal reproducing circuit includes a magneto-resistive effect head having one end thereof coupled to a first power supply line, for reproducing data recorded on a magnetic recording medium in a read operation. A first constant current source is coupled between another end of the head and a second power supply line, for supplying the head with a sense current in the read operation. First and second transistors have collectors thereof coupled to the first power supply line, and are responsive to voltage signals obtained from both ends of the head, respectively. Second and third constant current sources are coupled between each emitter of the first and second transistors and the second power supply line, respectively, for supplying the first and second transistors with a predetermined constant current in the read operation. A capacitor is connected between each emitter of the first and second transistors. A control circuit responsive to a read/write control signal controls respective ON/OFF timings of the first to third constant current sources. The control means controls at least one signal reproducing circuit portion corresponding to nonselected heads to be brought to a read state when a signal reproducing circuit portion corresponding to a selected head is in a write state.

Signal reproducing circuit adapted for head utilizing magneto-resistive

A signal reproducing circuit includes: a magneto-resistive effect head having one end thereof coupled to a first power supply line, for reproducing data recorded on a magnetic recording medium in a read operation; a first constant current source coupled between another end of the head and a second power supply line, for supplying the head with a sense current in the read operation; first and second transistors having collectors thereof coupled to the first power supply line, and responsive to voltage signals obtained from both ends of the head; second and third constant current sources coupled between each emitter of the first and second transistors and the second power supply line, for supplying the first and second transistors with a predetermined constant current in the read operation; a capacitor connected between each emitter of the first and second transistors; and a control circuit responsive to a read/write control signal, for controlling respective ON/OFF timings of the first to third constant current sources. In a transition from a read state to a write state, the second and third constant current sources are first turned OFF and the first constant current source is then turned OFF. In a transition from a write state to a read state, the first constant current source is first turned ON and the second and third constant current sources are then turned ON. It is possible to reduce a transient idle period from a write state to a read state to thereby prevent an undesirable offset component from overlapping the reproduced signal, and to reduce a loss in the data capacity to a minimum.

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Higashine, Japan

Hidekazu Shibasaki