MAGNETIC INFORMATION REPRODUCER

摘要

PURPOSE:To obtain a magnetic information reproducer having high S/N by flowing a pulse current to increase the signal voltage obtained from a magneto- resistance element by >=10 times as high as a normal level to secure a constant current through a bridge circuit as well as to extract the signal voltage component obtained from a signal magnetic field. CONSTITUTION:A feedback loop uses a dummy resistance element 22 as a magneto-resistance element 12 and impresses a DC magnetic field corresponding to the reproduction signal output to the element 22 in order to control the resistance value to an optimum level. A DC component is supplied to a conductor pattern 23 from the output of a sample and hold circuit 19 via an extracting circuit 24 and an amplifier 25. The DC magnetic field impressed to the element 22 is changed to minimize the DC component contained in the reproduction signal output. Then the resistance value of the element 22 changes. Therefore the balance conditions of a bridge circuit 13 can always be maintained by the function of the feedback loop although the resistance value of the element 12 increases due to the wear. Thus it is possible to secure the reproduction signal corresponding to the recorded magnetic information by detecting the voltage change.