Hitachi, Ltd.

Akio Shioya

Yuji Hata

Masahito Kobayashi

Yoshio Soyama

Iwao Oshimi

A disk apparatus has a position signal detector for detecting the position of a head with a specified sampling period, a controller operating a manipulated variable to control positioning of the head using a microprocessor and a digital/analogue converter with which the manipulated variable is converted. At least one or more timing registers set the timing of the conversion carried out by the D/A converter and at least one or more manipulated variable registers set a manipulated variable that is converted into digital/analogue form at the set timing. In addition, the controller has advancing means to make a target position trajectory advance towards a specified time, a feedforward controller to receive the output of the advancing means and to calculate a feedforward control variable on the basis of a target trajectory, and a feedback controller to produce a feedback output variable on the basis of a target trajectory that is delayed relative to a target position trajectory by a specified time.

Disk apparatus and method of controlling disk apparatus

When a magnetic recording and reproducing apparatus is in a waiting state, feedback control for positioning the carriage is released, and a supply of a sense current to the magnetoresistive effect element of the MR magnetic head is adjusted so as to prolong the life of the MR magnetic head. When the interface and control circuit recognizes that there is no order from the host computer and that the magnetic recording and reproducing apparatus is in a wait state, the servo control circuit releases the feedback control for positioning the head. A mode, etc. selection control circuit controls the recording/reproduction amplifier so as not to supply a sense current to the magnetoresistive effect element of the MR magnetic head. Accordingly, the time for supplying a sense current to the magnetoresistive effect element of the MR magnetic head is reduced in a great measure and, therefore, it is possible to prevent the deterioration of the element characteristics by electro-migration or the like. The result is that the life of the element can be prolonged. Hence, the output of the MR magnetic head can be increased without sacrificing the reliability. Accordingly, it has become possible to improve the performance of a high-output magnetic recording and reproducing apparatus using an MR magnetic head.

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Shizuoka-ken, Japan

Akio Shioya