Surface Capacitive
Sensor Materials
Glass substrate, transparent metal oxide coating
Principle of Operation
- Voltage is applied to the corners of the touch screen.
- A pattern of electrodes around the periphery of the touch screen distribute the voltage to form a uniform electric field across the conductive surface.
- A finger touch draws a minute amount of current from the surface and is measured by the controller.
- The relative magnitude of current is inversely proportionate to the distance from the contact point to the touch screen corners.
- Ratios of the four corner currents are calculated to determine the X,Y coordinate.
Advantages
- Withstands contaminants and moving liquids on the screen, and continues to function over entire touch screen area
- Very light finger touch required for activation
- Technology with fastest touch response time
- Transmission typically 88% to 92%
Disadvantages
- Supports only finger or tethered pen
- Severe scratch can affect operation within the damaged area
- Limited to 1 resolvable point with gesture capability