MULTI-CHANNEL REPRODUCING CIRCUIT

摘要

PURPOSE:To obtain the reproduction signals by providing a dummy multi-channel MR head which is well balanced with a multi-channel MR head to obtain a difference signal of the same junction to extract an AC signal and then to obtain a difference signal between said difference and AC signals. CONSTITUTION:The electric resistance values of MR heads 21-24 of a magneto- resistance effect element group A are varied by the magnetic field generated from a magnetic medium. While dummy MR heads 26-29 of a magneto-resistance element group B receive no magnetic field and therefore have no change of their resistance values. The level of DC voltage is equal between an MR head 22 and a dummy MR head 27 at the high potential side. These DC voltages are supplied directly to the differential input of a differential amplifier 31. Thus the DC signal of the high potential side of the head 22 is obtained at the output of the amplifier 31. At the same time, the AC signal of the low potential side of the head 22 is obtained at the output of a differencial amplifier 32. Therefore the difference signal of output between amplifiers 31 and 32 is equal to the AC signal, i.e. the reproduction signal generated between both terminals of the head 22. It is possible to improve the performance and to realize miniaturization by unifying a thin film magnetic head and its peripheral circuits.