Kabushiki Kaisha Toshiba

Hiroyuki Naka

Yuji Sakai

Yusuke Ohinata

A magnetic head testing apparatus having the function of evaluating pin holes in a tunnel barrier layer of a TMR element by a non destructive inspection is disclosed. The testing apparatus comprises a temperature control unit which sets a circumferential temperature of a TMR element, a bias electric current control unit which applies an electric current for measuring a resistance value, an element resistance measuring unit and a CPU which calculates a temperature coefficient. The CPU determines a pin hole state in the tunnel barrier layer based on the temperature coefficient.

Method and apparatus for testing magnetic head with TMR element

In a data-recording mode, a driver circuit supplies a recording head with a recording current corresponding to write data. In a degaussing mode, the driver circuit supplies the recording head with a degaussing current for eliminating the residual magnetism of the head as the recording current. The degaussing current has a rising period and falling period set longer than those of the recording current supplied in the data-recording mode.

Head amplifier circuit with function for degaussing residual magnetism of recording head

A disk drive is disclosed which has a facility to perform a pinning reset operation on a GMR read element included in a head if a read retry operation fails to achieve recovery from a read error. When a bias and write currents are supplied to the head, a CPU of the disk drive determines an optimum bias and write currents on the basis of a temperature measured value of the GMR read element.

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Ome, Japan

Hiroyuki Naka