Patent ID: 6437318
Filing Date: 2002-08-20
Classification: G01D,G06F

Abstract:
A computer input device having an encoder, said encoder comprising:a movable element for providing an input to a host computer, wherein said movable element is responsive to a movement of said input device by an operator of said host computer; a first polarized filter coupled to said movable element so that said first polarized filter moves proportionately to said movable element; a second, stationary polarized filter adjacent said first polarized filter; a photoemitter mounted on a first side of said first and second polarized filters; and a first photodetector mounted on a second side of said first and second polarized filters, said first photodetector providing a signal proportional to an amount of movement of said movable element, such that the relative positions of said first and second polarized filters provides a modulated light to said first photo detector thus providing an indication of a relative movement of said input device.