Cahill, Sutton & Thomas
Four button cursor and method for digitizing tablet
A cordless four button cursor unit for accurately digitizing points along a digitizing tablet surface has an insulative housing including four buttons, each shaped as a quadrant of a circle and arranged about a hub. The hub acts as a stationary support from which an operator's fingers can conveniently "roll" to actuate any of the buttons. An antenna loop integral with a printed circuit board extends forward of the housing and subtends a cross hair on the bottom surface of a transparent substrate. A pair of conductive touch plates on opposite sides of the housing are short circuited by the resistance of an operator's hand, enabling an oscillator to effectuate operation of the cursor unit, causing the antenna to transmit electrostatic signals of frequencies representing button commands. The capacitance of the operator's body adds to the ground plane capacitance, so that transmission of electrostatic signals by the ground plane to the digitizing tablet is avoided. When the opeator's hand breaks contact with the touch plates, the oscillator is disabled before data errors can be produced by the resulting decrease in gound plane capacitance.
Kurta Corporation
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inventional inventional
James L.
Rogers