Patent ID: 7675283

Claim:
A relative position detection device comprising a first member, a second member being capable of displacement in a relative displacement direction relative to the first member, the first member comprising a magnetic portion, the magnetic portion generating a magnetic field, the second member comprising a first Hall Effect sensor, the first Hall Effect sensor being positioned within the magnetic field without any intervening magnetic material positioned directly between the first Hall Effect sensor and the magnetic portion of the first member, the first Hall Effect sensor adapted to output a detection signal from a flux density of the magnetic field generated by the magnetic portion, the magnetic portion comprising an S-pole section and an N-pole section that are arranged along the first member side by side in the relative displacement direction, and the first Hall Effect sensor being configured to sense the flux density of the magnetic field at all times throughout a full range in which the first member and the second member displace relative to each other, the detection device further comprising a second Hall effect sensor configured to detect movement of the first member.