Resistive touch screens have a flexible top layer and a rigid bottom layer separated by insulating dots, with the inside surface of each layer coated with a transparent conductive coating. Voltage applied to the layers produces a gradient across each layer. Pressing the flexible top sheet creates electrical contact between the resistive layers, essentially closing a switch in the circuit.

5 Wire Resistive

In 5 Wire resistive, the main electronics are on the glass bottom layer. A uniform voltage is applied to the top plastic layer. A touch causes an electrical contact between the top and bottom layers. Depending on the point of touch the voltages at the 4 corners of the glass are different—these are measured, and used by a complex algorithm in the controller to calculate the x-y coordinate of the point of touch.

The technology and electronics being more complex results in 5 wire being more expensive than 4 wire technology. But the complex electronics makes it possible to use 5 wire for sizes upto 22”, larger than with 4 wire. Also, since the voltage measurement is on the stable glass bottom layer, despite damage to one portion of the top layer the touchscreen keeps working

4 Wire Resistive

Touch measurement in 4 Wire technology is a 2 step process. First, the distance along the x axis at the point of touch is measured by creating a horizontal voltage gradient on the top sheet, with the bottom acting as the return layer. Second a vertical voltage gradient is created on the bottom layer, to measure the y axis.

The technology and electronics are simple, making 4 wire the cheapest touchscreen technology. But since the voltage gradient is needed on both the layers, any damage to either layer causes the touchscreen to stop functioning. And damage is easy, since often both layers are plastic. This lack of durability means that 4 wire technology should not be used for applications like public access kiosks, industrial locations or on displays larger than 12”.

8 Wire Resistive

Similar construction to 4 Wire, but with the addition of 4 sense wires, 2 on each layer. These are for referencing of voltage on the layers, enabling self-correction of changes with material age. Uses are the same as for 4 wire, but with more stability over a period of time.

Digital Matrix

Digital Matrix touchscreen, provides greater flexibility thantraditional membrane switches allowing on-screen soft buttons which can be easily modified,upgraded, or expanded. In contrast, a membrane switch requires a change in hardware to redefinebutton layout or functionality. TouchTekDM can also be used in hybrid applications where buttons defined by graphics are printed around the touchscreen perimeter, similar to a membraneswitch, except with a transparent window over the LCD for customizable functions.

For TouchTekDM, the ITO conductive material is patterned into rows and columns in the form of a grid. Each etched layer has a voltage connection. When the layers are pressed together, cur-rent flows through the row and column where the touch occurs to calculate the position of thetouch.