Resistive Touchscreen
(for 90% of all touchscreen applications)
The resistive touchscreen uses a glass panel overlay with a uniform resistive coating. A polyester coversheet is tightly suspended over the top of the glass, separated by small, transparent insulating dots. The coversheet has a hard durable coating on the outer side and a conductive coating on the inner side. When the screen is touched, the conductive coating makes electrical contact with the coating on the glass. The voltages produced are the analog representation of the position touched. The controller digitizes these voltages and transmits them to the computer for processing.

Surface Acoustic Wave Touchscreen
(safest touchscreen for hazardous area applications)
The Surface Acoustic Wave Touchscreen has a glass overlay with a grid of transmitting and receiving piezoelectric transducers. The touchscreen controller sends a 5 mHz electrical signal to the transmitting transducer, which converts the signal into ultrasonic waves within the glass. When the screen is touched, a portion of the wave travelling across it is absorbed, thus changing the received signal. The signal is then compared to a stored reference signal, the change recognized, and a coordinate calculated. The process happens independently for both the X and Y axes. By measuring the amount of the signal that is absorbed, a Z-axis is determined.

Infrared Touchscreen
(for applications where touchscreen is exposed to extreme abuse)
The Infrared Touchscreen relies on the interruption of an IR light grid in front of the display screen. Integrated into the display bezel is an opto-matrix frame that contains a row of IR-light emitting diodes (LEDs) and photo transistors, each mounted on two opposite sides to create a grid of invisible infrared light. The opto-matrix frame is isolated from the outside environment by an IR transparent barrier. The IR controller sequentially pulses the LEDs to create a grid of IR light beams. When a stylus, such as a finger, enters the grid, it obstructs the beams. One or more of the phototransistors detects the absence of light and transmits a signal that is the X and Y coordinates. Because the infrared scanning is done in front of the display, a bullet-proof, 3/8" thick polycarbonate window is installed between the IR grid and the display itself. This window provides a level of environmental protection for the electronics that is unique to the infrared touchscreen technology.

Near Field Imaging™ Touchscreen
(for applications that require accuracy, touch sensitivity, and durability)
The Near Field Imaging (NFI) Touchscreen consists of two laminated glass sheets with a patterned coating of transparent metal oxide between them. An ac signal is applied to the patterned conductive coating creating an electrostatic field on the the surface of the screen. When a finger—gloved or ungloved—or other conductive stylus comes in contact with the sensor, the electrostatic field is disturbed.