Touching the overlay surface causes the (2) Upper Resistive Circuit Layer to contact the (4) Lower Resistive
Circuit Layer, producing a circuit switch from the activated area.
The touchscreen controller gets the alternating voltages between the (7) two circuit layers
and converts them into the digital X and Y coordinates of the activated area.
What is a touchscreen?
A touchscreen is any monitor, based either on LCD (Liquid Crystal Display) or CRT (Cathode Ray Tube) technology, that accepts direct onscreen
input. The ability for direct onscreen input is facilitated by an external
(light pen) or an internal device (touch overlay and controller)
that relays the X,Y coordinates to the computer.
Resistive Touchscreen Technology
Resistive LCD touchscreen monitors rely on a touch overlay, which is composed of a flexible top layer
and a rigid bottom layer separated by insulating dots, attached to a touchscreen controller. The inside surface of each of the two layers is coated with a transparent metal
oxide coating (ITO) that facilitates a gradient across each layer when voltage is applied. Pressing the flexible top sheet creates electrical contact between the resistive
layers, producing a switch closing in the circuit. The control electronics alternate voltage between the layers and pass the resulting X and Y touch coordinates to the touchscreen controller.
The touchscreen controller data is then passed on to the computer operating system for processing.
Resistive touchscreen technology possesses many advantages over other alternative touchscreen technologies (acoustic wave, capacitive, Near Field Imaging, infrared).
Highly durable, resistive touchscreens are less susceptible to contaminants that easily infect acoustic wave touchscreens. In addition, resistive touchscreens are
less senstive to the effects of severe scratches that would incapacitate capacitive touchscreens. For industrial applications, resistive
touchscreens are much more cost-effective than Near Field Imaging touchscreens are.
Because of its versatility and cost-effectiveness, resistive touchscreen technology is the touch technology of choice for many markets and applications. Resistive
touchscreens are used in food service, retail point-of-sale (POS), medical monitoring devices, industrial process control and instrumentation, portable and handheld
products.
Resistive touchscreen technology exists in 4-wire, 5-wire, or 8-wire forms. FastPoint LCD touchscreens
specifically employ 8-wire resistive technology because of its benefits over its counterparts. Whereas 8-wire FastPoint touchscreens are available in all sizes,
4-wire resistive technology is restricted to small flatpanels
(<10.4").
Additionally, 8-wire resistive touchscreens are not susceptible to problems caused by high-level short-term variances and axis linearity and drift.
