Five-Wire Resistive
As we have seen, four- and eight-wire touchscreens, while having a simple and elegant design, have a major drawback in terms of durability in that the flexing coversheet is used to determine one of the axes. Field usage proves that the other axis rarely fails. Could it be possible to construct a touchscreen where all the position sensing was on the stable glass layer? Then the coversheet would serve only as a voltage probe for X and Y. Microscopic cracks in the coversheet coating might still occur, but they would no longer cause non-linearities. The simple buss bar design is not sufficient and a more complex linearization pattern on the edges is required.
In the five-wire design, one wire goes to the coversheet (E) which serves as the voltage probe for X and Y. Four wires go to corners of the back glass layer (A, B, C, and D). The controller first applies 5V to corners A and B and grounds C and D, causing voltage to flow uniformly across the screen from the top to the bottom. Upon touch, it reads the Y voltage from the coversheet at E. Then the controller applies 5V to corners A and C and grounds B and D, and reads the X voltage from E again.
So, a five-wire touchscreen uses the stable bottom layer for both X- and Y-axis measurements. The flexible coversheet acts only as a voltage-measuring probe. This means the touchscreen continues working properly even with non-uniformity in the coversheet's conductive coating. The result is an accurate, durable and more reliable touchscreen over four- and eight-wire designs.
Sent factory direct delivery is normally 3-5 working days
