Sensing the size of a touch point in a touch-sensitive panel employing resistive membranes

A touch screen such as an electronic whiteboard that detects the size of a touch as well as the touch's location on the touch screen. The size of the touch or a stylus mode based on the size of the touch is then reported to an application program by the touch screen and the application program uses the size or mode to determine what operation is to be performed at the location of the touch. In the exemplary implementation, the size of the touch determines whether the stylus mode is erasing or non-erasing. A user of the touch screen can thus switch from writing to erasing simply by switching from a marking pen to an eraser that is broader than the marking pen. In the exemplary implementation, the touch panel is a resistive membrane touch panel and touch size is detected from a touch resistance that is determined by subtracting other components of the total resistance of a circuit that arises when the touch panel is touched.