A new contactless trackball design using Hall effect sensors

In this paper, a new trackball design based on a non-contacting motion detection mechanism is analyzed. It utilizes the hysteresis phenomenon of magnetic grade steel. In this design, the ball and a pair of electromagnets are made from magnetic grade stainless steel material. The electromagnets are placed outside and near to the ball surface. They record the magnetic information onto the ball surface. A Hall sensor, acting as a magnetic field detector, is placed inside each electromagnet. As the ball moves, the magnetic field recorded onto the ball surface produces instantaneous changes in the Hall sensor output. This output is then converted into a suitable format in order to determine the speed and direction of motion of the ball. Tests have been performed to check the viability of this technique. The promising test results have lead to the successful development of a prototype trackball.