Patent ID: 7852070

Claim:
An angle sensor using a displacement sensor comprising: a sensor element having a first magnetic layer whose magnetization direction is set in a predetermined direction without being influenced by an external magnetic field and a second magnetic layer whose magnetization direction varies against the external magnetic field; magnetic field generating means for supplying the external magnetic field; and power supply means for supplying drive voltage to said sensor element; wherein a change in resistance value of said sensor element proportional to the difference in a magnetized state between a magnetized state of said second magnetic layer and a magnetized stage of said first magnetic layer, which occurs depending on a relative positional relation between said magnetic field generating means and said sensor element, is detected to detect a relative positional relation between said magnetic field generating element and said sensor element; and said displacement sensor further comprises suppressing means for suppressing an anisotropic magnetoresistive effect which occurs in said second magnetic layer and which is attributable to an electric current flowing in said sensor element on the basis of said drive voltage; and wherein the angle sensor comprises: a stator section having a plurality of giant magnetoresistive elements of a multi-layer structure, said giant magnetoresistive elements each having at least a fixed magnetic layer having a fixed magnetization direction, a non-magnetic conductive layer and a free magnetic layer; and a rotor section adapted to form a magnetic field and rotate in opposition to said stator section, a rotational angle of said rotor section being detected from a change in resistance value caused by the magnetic field provided from said rotor section to said GMR elements; characterized in that at least two Wheatstone bridge circuits having a predetermined angular offset are installed in said stator section, said Wheatstone bridge circuits each comprising a plurality of GMR elements each having a fixed magnetic layer set in a predetermined magnetization direction, an AC power supply is used as a power supply for said Wheatstone bridge circuits, an alternating current is made flow in said plural GMR elements and a rotational angle is detected on the basis of AC-modulated outputs provided from said Wheatstone bridge circuits.