DETECTING METHOD AND DETECTOR FOR MAGNETIC BODY PASSING BY AUTOMATIC GAIN CONTROL

摘要

PROBLEM TO BE SOLVED: To provide the approach detector, which can perform the detection at the speed to zero, which generates the binary output voltages in more accurate correspondence with the approach point, where transition can be accurately estimated, and the separating point with regard to the transducer of the approach detector for a passing magnetic body. SOLUTION: An approach detector for a passing magnetic body includes a magnetic-field/voltage transducer 10, which detects the surrounding magnetic field and generates a voltage Vh having the amplitude directly related to the magnetic field. An amplifier 12, whose gain is digitally controlled, is connected to the transducer 10 for amplifying voltage Vh. A DC voltage source for forming a target voltage VTG is provided. Comparators means 14, 24, 18 and 26 have inputs connected to the output of the amplifier 12 and the DC reference voltage for forming the binary signal, which is changed from one binary level to another level every time a binary signal Vsig exceeds the target voltage VTG.