Basic Construction and Theory of Operation
TPI’s VersaTouch8® touchscreens are constructed of two electrically conductive and transparent layers (ITO coated film or glass). The opposing layers of VersaTouch8® are held apart by nearly invisible separator dielectric dots. The layers are held together and sealed with a gasket adhesive which isolates the touchscreen from the outside environment.
Parallel busbars, consisting of screen-printed conductive ink, are positioned along the opposite edges of each layer and orthogonal to the busbars on the other layer. In addition, sensing busbars are screen-printed on the conductive surface parallel and immediately adjacent to the main busbars.
Applying pressure to the flexible top layer creates a contact between the two conductive surfaces and completes the circuit. An electronic controller circuit performs the voltage switching and sensing to determine the touch position. Presence of the sensing busbars in conjunction with circuits in the electronic controller provides means for self calibration. Self calibration overcomes voltage variations caused by changes in silver and ITO resistance due to aging and environmental factors.