Patent ID: 6034624
Filing Date: 2000-03-07
Classification: G01B,G01D

Abstract:
An induction-type linear position detector device comprising:a winding section including a primary winding to be excited by a single-phase A.C. signal and at least two groups of secondary windings positioned so as to produce A.C. output signals according to predetermined different amplitude functions in response to linear movement of an object of detection within a predetermined range; anda variable magnetic coupling section movable relative to said winding section in response to a varying linear position of the object of detection, and including a plurality of magnetic response members with a predetermined magnetic response characteristic provided in repetition at a predetermined pitch along the direction of linear movement, wherein magnetic coupling between said primary winding and said secondary windings is varied in response to the varying linear position of the object of detection as positions of said magnetic response members relative to said winding section changes in response to movement of said variable magnetic coupling section relative to said winding section, so that said variable magnetic coupling section allows inductive A.C. output signals, amplitude-modulated in accordance with a current linear position of the object of detection, to be produced in said secondary windings with amplitude function characteristics differing depending on positional differences between said secondary windings,wherein the inductive A.C. output signals produced in said groups of said secondary windings are identical in electrical phase, each of the inductive A.C. output signals varies in its amplitude function in periodic cycles each corresponding to the pitch length of said magnetic response members, the amplitude function of a first one of groups of secondary windings is a sine amplitude function, and a second one of groups of secondary windings is a cosine amplitude function, andwherein said linear position detector device further comprises a phase detecting circuit that receives first and second A.C. output signals from said first and second groups of secondary windings and detects phase values of said sine and cosine amplitude functions corresponding to amplitude values of said first and second A.C. output signals.