Patent ID: 7456758
Filing Date: 2008-11-25
Classification: B82Y,G01D,G01R,G11B

Abstract:
1. A magnetic encoder, comprising: a magnetic medium on which an area with the width of λa magnetized in a first direction and an area with the width of λb magnetized in a second direction are alternately disposed; and a magnetoresistive sensor formed by arranging a plurality of sensor units at intervals in a width direction of the area, each of the sensor units being formed of a magnetoresistive film patterned into a strip-like shape, the magnetoresistive film having a structure in which a soft magnetic free layer, a non-magnetic intermediate layer and a ferromagnetic pinned layer are stacked, a magnetization direction of the soft magnetic free layer changing in response to an external magnetic field, wherein the soft magnetic free layer of the sensor units has a structure in which a first soft magnetic film, an anti-parallel coupling film and a second soft magnetic film are stacked in sequential order from a side of the non-magnetic intermediate layer; and magnetizations of the first soft magnetic film and the second soft magnetic film are magnetically coupled to each other in anti-parallel directions, and the magnetic encoder outputs an electric signal having a period of λ=(λa+λb)/2.