The present invention relates to a magnetic head device and, more particularly, to a magnetic head device of thin-film type.
In general, a known magnetic head device of a thin film type has a lower magnetic layer made of a soft magnetic material, a gap made of a non-magnetic material and an upper magnetic layer which are laminated in the mentioned order on a substrate made of a non-magnetic material, so as to form a ring-like magnetic circuit. At the same time, a coil is arranged to wind around with this magnetic circuit.
When the magnetic head device is used for a recording purpose, a signal current is supplied to the coil so that a magnetic field is generated at the gap in accordance with the signal current, so that the signals are magnetically recorded in a recording medium by the magnetic field. Conversely, when the magnetic head device is used for reproducing purpose, a signal magnetic field introduced through the gap is detected by the coil.
In the conventional thin-film magnetic head device of winding type, the same magnetic structure is driven both in the recording and the reproduction. This means that the track width is the same both in the recording and reproducing phases, so that the recording and reproducing performance is often impaired due to the following reasons.
In general, a magnetic head device inevitably exhibits an off-track due to a running offset during running of the recording medium. Representing the track width of the thin-film magnetic head by T and the amount of running offset of the recording medium by .+-.a, the deviation of the track between the recording phase and the reproducing phase is 2a at the maximum. In such a case, the effective reproduction track width is reduced to (T-2a), so that the reproduction output is decreased undesirably.