AR1000 Datasheet, PDF (30/37 Pages) Microchip Technology – Resistive Touch Screen Controller

8.3 4-Wire Sensor
A 4-wire resistive touch sensor consists of a Stable and Flex layer, electrically separated by spacer dots. The
layers are assembled perpendicular to each other. The touch position is determined by first applying a voltage
gradient across the flex layer and using the stable layer to measure the flex layer’s touch position voltage. The
second step is applying a voltage gradient across the stable layer and using the flex layer to measure the stable
layer’s touch position voltage.
The measured voltage at any position across a driven axis is predictable. A touch moving in the direction of the
driven axis will yield a linearly changing voltage. A touch moving perpendicular to the driven axis will yield a
relatively unchanging voltage.
Figure 14: 4-Wire Decoding
DS41393A-Page 26
© 2009 Microchip Technology, Inc.