Patent ID: 6563306
Filing Date: 2003-05-13
Classification: G01B,G01D,G01F

Abstract:
An apparatus for detecting the displacement of the magnet, the apparatus being characterized in that it further comprises a plurality of hall devices disposed in a predetermined spacing DP along a displacing path of the magnet in parallel thereto, whereineach of said hall devices includes a magnetically sensitive surface through which a magnetic flux from said magnet permeate to generate an output the polarity and the voltage of which are depend on the direction and the density of the magnetic flux, and said magnetically sensitive surface of each hall device is disposed in a predetermined distance from the displacing path of the magnet in parallel with the direction defined by the magnetic poles, and wherein two adjacent (n)th and (n+1)th hall devices (n=0, 1, 2, . . . ) inverted in the polarity of their output voltages V(n) and V(n+1) are detected to determine the general position of the magnet, and the precise position of the magnet between these two hall devices is determined on the basis of the following equation; MP=nÂ·DP+[V(n)/{V(n)âˆ’V(n+1)}]Â·DP.