A CMOS motion detector system for pointing devices

The blocks of an optical motion detection microsystem are: a ball with a printed pattern of spots that contrasts with the background color; LEDs to illuminate part of the ball; a lens to focus an image onto the surface of a chip; a CMOS chip composed of an array of photodetectors and processing circuits outputting signals to a microprocessor; a microprocessor to establish the protocol for communications with the personal computer and to generate required interrupts. The approach presented here improves on previously-proposed solutions by reducing the system power consumption by at least two orders of magnitude, increasing the tracking resolution to 800dpi, and by requiring only a random-size, -shape and -position pattern printed on the surface of the ball instead of a precise regular pattern that is difficult to manufacture.