Angle sensor

Abstract

To provide an angle sensor which can equalize the magnetic flux distribution while using inexpensive magnets manufactured easily and which can reduce the detection error even if the relative position between the magnetoelectric conversion element and the magnet changes. The permanent magnets M 1 a , M 1 b , M 2 a , M 2 b each of which is rectangular solid are fixed to the yoke 13 of the rotational angle displacement sensor 11 . The permanent magnets M 1 a , M 1 b are separated from each other with a clearance L. The permanent magnets M 1 a , M 1 b are magnetized in such a manner that the side fixed to the flat wall portion 15 a of the yoke 13 is N pole and that the side opposing to the fixed surface side is S pole. Further, the permanent magnets M 2 a , M 2 b are separated from each other with a clearance L. The permanent magnets M 2 a , M 2 b are magnetized in such a manner that the side fixed to the flat wall portion 15 b of the yoke 13 is S pole and that the side opposing to the fixed surface side is N pole.

What is claimed is:  
     
         1 . An angle sensor comprising: a tubular yoke fixed to a rotational member; magnets fixed to an inner side surface of the tubular yoke and rotating around a rotational central axis of the rotational member; and a magnetoelectric conversion element disposed in magnetic field generated by the magnet and outputting an electric signal corresponding to the magnetic field; wherein the magnets include four piece of magnets, two piece of the magnets form a magnetic pole of one side and other two piece of the magnets form a magnetic pole of the other side, and wherein the magnets forming the magnetic pole of one side and the magnets forming the magnetic pole of the other side are separated from each other and are fixed to the inner side surface of the tubular yoke.  
     
     
         2 . An angle sensor comprising: a cylindrical magnet fixed to a rotational member and rotating with the rotation of the rotational member; and a magnetoelectric conversion element disposed in magnetic field generated by the magnet and outputting an electric signal corresponding to the magnetic field; wherein a magnetic flux density distribution correction portion is formed on an outer circumferential surface of the magnet.