A surface-mount pointing device controls the movement of an object on a display screen. The device has a base and a shaft. The shaft is mounted to the base. Several sensors are mounted on the base and around the shaft for sensing the amount of strain in the base that is created in response to a force...http://www.google.es/patents/US6323840?utm_source=gb-gplus-sharePatente US6323840 - Surface-mount pointing device
