Patent ID: 7211999

Claim:
A rotation angle detector for detecting a rotation angle of a shaft member, comprising: a rotary member which is to be rotated in association with the shaft member; a first detection member to be rotated in association with said rotary member; a second detection member to be rotated in association with said rotary member; a first magnet to be rotated integrally with said first detection member; a second magnet to be rotated integrally with said second detection member; a first magnetic sensing device opposed to said first magnet; a second magnetic sensing device opposed to said second magnet; and a controlling circuit for calculating a rotation angle of the shaft member based on detection signals outputted from said first and second magnetic sensing devices, wherein said first magnet includes a first section on a side facing said first magnetic sensing device, and a second section on a side facing away from said first magnetic sensing device, with the north pole and the south pole of said first section being arranged in a reversed manner relative to the north pole and the south pole of said second section.