METHOD AND APPARATUS FOR DETECTING TWO SIMULTANEOUS TOUCHES AND GESTURES ON A RESISTIVE TOUCHSCREEN

摘要

A resistive touchscreen system (100) has a coversheet (102) with a first conductive coating (106) having a first resistance and a substrate (104) with a second conductive coating (108) having a second resistance. The coversheet and the substrate are positioned proximate each other such that the first conductive coating faces the second conductive coating. The coversheet and the substrate are electrically disconnected with respect to each other in the absence of a touch. First and second sets of electrodes (1 10,1 12 and 120,122) for establishing voltage gradients in first and second directions are formed on the coversheet and the substrate, respectively. A controller (138) biases the first and second sets of electrodes in two different cycles. The controller senses a bias current associated with at least one of the first and second resistances. The bias current has a reference value associated with no touch. An increase in the bias current relative to the reference value indicates two simultaneous touches.