Two-dimensional position detection system with MEMS accelerometers, readout circuitry, and microprocessor for padless mouse applications

A hybrid two-dimensional position sensing system is designed with microelectromechanical systems (MEMS) for padless mouse applications. The X/Y-axis acceleration of the user´s hand movements is measured by two MEMS accelerometer devices. These acceleration values are pulsewidth modulated and converted into (X, Y) coordinates on the screen by integral operations on a microprocessor. The overall system consists of four major components: 1) MEMS accelerometers; 2) CMOS analog readout circuitry; 3) an acceleration magnitude extraction module; and 4) a 16-b RISC microprocessor. Mechanical and analog simulation shows that the designed mouse system can detect acceleration as small as 5.3 mg (g=9.8 m/s/sup 2/) with 100-kHz sampling frequency for low power consumption.