JPS646701A - Non-contact displacement detector - Google Patents

Abstract

PURPOSE:To achieve a higher sensitivity employing a permeance distribution type, by a method wherein yokes are projected separately from N and S poles of a magnet to make a Hall effect element and the yokes are so shaped to open wider toward the tip thereof when a moving object is advanced thereinto to detect the position thereof in a non-contact manner. CONSTITUTION:Planar yokes 1a and 1b are mounted being opened wider separately from S and N poles at an end face of one magnet 2 to form a Hall element 3 and a moving object 4 is advanced from the opening thereof to detect a displacement of the moving object 4 from changes in a space from the magnet 2. With such an arrangement, when Z=0 and the length in the X axis is represented by lm and the length of a gap between the yokes 1a and 1b at a point at a distance generated by Z in the direction Z from the point of Z=0 by lg(Z), the position of the object 4 at one end of the magnet 2, namely, on the entry side thereof 4 is prescribed by lg(Z)=lm(1+2a/lmXZ). Thus, when internal intensity of a magnetic field is represented by Hm, density of residual flux Br, coercive force Hc and permeance factor p, the Hm at a working point can be determined by BrHC/pHc+Br to detect a displacement using the results.