The present disclosure discloses an object position detector. The object position detector comprises a touch sensor formed as a closed loop and having a physical constraint formed on an upper surface of the touch sensor and coextensive with the closed loop. The touch sensor is configured to sense motion...http://www.google.com/patents/US7466307?utm_source=gb-gplus-sharePatent US7466307 - Closed-loop sensor on a solid-state object position detector
