METHOD AND APPARATUS FOR DETECTING PASSING MAGNETIC OBJECT

摘要

PROBLEM TO BE SOLVED: To enable clear detection of a passing magnetic object by making periodic update so that percentage of voltage is maintained within a predetermined tolerance in response to a change which can occur on peak voltage of threshold voltage Vsig . SOLUTION: Threshold voltages VNth and VPth are indicated at an approximate 173 and 2/3 of a path of a resistance voltage divider 34, respectively. Even when peak voltage of Vsig varies or offset voltage contained in Vsig varies, it is understood that the threshold voltages VNth and VPth have been adjusted after each update period so that they are kept at a fixed percentage of peak-to- peak voltage of Vsig . These thresholds vary with time and exhibit a fixed percentage of peak-to-peak differential voltage (updated) at that time always in the signal Vsig . This is remarkably advantageous in that a proximity detector applies binary output voltage further corresponding to a clear approach point and a retreat point of a magnetic object with transition passing when operating in a peak-to-peak percent threshold mode.