Importance

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Abstract

A multi-electrode capacitive position sensor functions as part of a computer pointing device that can be integrated with the computer's keyboard and that employs ratiometric capacitive sensing techniques. This approach allows a computer user to move a cursor about on a display by skimming his or her fingers over the keyboard without actually depressing any of the keys. The preferred sensing arrangement comprises a circuit for first charging a resistive layer disposed on an active portion of the keyboard and then discharging the layer by simultaneously connecting each of several spaced-apart electrodes to respective inputs of a multi-channel charge detection circuit. For a one-dimensional pointing device, two or more charge transferring switches and electrodes are required, with two being the preferred number. For a two-dimensional pointing device, three or more charge transferring switches and electrodes are required, with four being a preferred number.

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First Claim