Patent ID: 7508196

Claim:
A magnetic sensor for a pointing device which detects a position of a magnet supported on a mounting substrate such that when an external operation force is applied to the magnet, the magnet moves from a predetermined initial position, the movement including a component parallel to a main surface of the substrate, wherein a straight line connecting the magnetization center of one magnetic pole of the magnet and the magnetization center of the other magnetic pole thereof perpendicularly intersects the main surface of the mounting substrate when the magnet is located at the initial position, the magnetic sensor comprising: a first giant magnetoresistance element which is fixedly secured to the mounting substrate such that the layer plane of a fixed layer thereof is parallel to the main surface of the mounting substrate, and the magnetization direction of the fixed layer coincides with a predetermined first direction, and is configured such that when the magnet is located at the initial position, the magnetization direction of a free layer of the element coincides with a direction which differs from the first direction by 90 degrees; a second giant magnetoresistance element which is fixedly secured to the mounting substrate such that the layer plane of a fixed layer thereof is parallel to the main surface of the mounting substrate, and the magnetization direction of the fixed layer coincides with a second direction, which is opposite to the first direction, and is configured such that when the magnet is located at the initial position, the magnetization direction of a free layer of the element coincides with a direction which differs from the second direction by 90 degrees; a third giant magnetoresistance element which is fixedly secured to the mounting substrate such that the layer plane of a fixed layer thereof is parallel to the main surface of the mounting substrate, and the magnetization direction of the fixed layer coincides with a third direction which differs from the first direction by 90 degrees, and is configured such that when the magnet is located at the initial position, the magnetization direction of a free layer of the element coincides with a direction which differs from the third direction by 90 degrees; and a fourth giant magnetoresistance element which is fixedly secured to the mounting substrate such that the layer plane of a fixed layer thereof is parallel to the main surface of the mounting substrate, and the magnetization direction of the fixed layer coincides with a fourth direction, which is opposite the third direction, and is configured such that when the magnet is located at the initial position, the magnetization direction of a free layer of the element coincides with a direction which differs the fourth direction by 90 degrees, wherein the position of the magnet is detected on the basis of resistances of the first through fourth giant magnetoresistance elements.