| 摘要 |
PURPOSE:To enable digital detection of the intensity of a magnetic field of a signal and thereby attain a sensor having high noise allowance, by impressing each of bias magnetic fields of alternating and direct currents on a magnetic resistance effect element. CONSTITUTION:The sensor has a constant-current source 8 supplying a constant current to a magnetic resistance effect element MR1, a conductor layer 7 set in parallel to MR1 through the intermediary of an insulator layer 6, a direct-current supply source 9 supplying DC bias current to the layer 7, an alternating- current supply source 10 supplying AC bias current thereto, and a regeneration circuit 11 detecting an output signal level of MR1. The respective bias magnetic fields of direct and alternating currents are impressed in the direction of (x) of MR1. Accordingly, when a signal magnetic field is given in the direction of (x) of MR1, the output of MR1 is amplified in alternating current and is further given to an amplitude demodulation circuit 19. Then, a demodulated output lowers sharply when the added intensity of the signal magnetic field and the respective bias magnetic fields of DC/AC approaches a saturation magnetic field. As the result, a regenerated output can be made into a pulsed signal of ON or OFF according to the magnitude of the signal magnetic field. |
