Magneto resistive sensor for detecting movement of a rotating body

Abstract

The invention discloses a movement detecting device for detecting the movement state of a moving body such as a rotating body, in which a magnetic recording medium on which N and S magnetic poles are alternately recorded at a constant interval is fixed symmetrically with respect to a rotary shaft of a rotating body whose rotation state is to be detected, and an MR element comprising magnet-resistive elements is mounted at a fixed position relative to the magnetic recording medium so that the rotation state of the rotating body can be detected from variation of the values of resistance of the magnet-resistive elements caused by the rotation of the body. N and S poles are recorded on the magnetic recording medium with a small pole pitch P. The magnet-resistive elements are formed to have a width sufficiently smaller than the pole pitch. The magnet-resistive elements constitute a first group and a second group, the magnet-resistive elements of each group being disposed with an interval equal to the pole pitch or half the pole pitch. The magnet-resistive elements are disposed in such a manner that the interval between the groups is deviated from the pole pitch, whereby a circuit comprising these magnet-resistive elements can detect the rotation of the rotating body.