Capacitive touch panel
Capacitive touch panel consists of multilayer coatings on a glass panel. The layered structure is shown in figure 2. Transparent conductive coatings are coated on both sides of the glass panel. Specially designed electrodes are laid around the panel’s edge on top of the front-side conductive coating to evenly distribute a low voltage across the front-side conductive coating, creating a uniform electric field. The backside conductive coating is used for electromagnetic interference (EMI) shielding. A hard coat layer is laid on top of the front-side conductive coating to provide protection to the front-side conductive coating. The layered structure is optimized to provide extraordinary optical quality and durability.
A finger touch draws a minute amount of current from the point of contact and creates an interruption of current flow through the electrode corners.
The controller measures the values of the current flow from the four corners and calculates the X, and Y coordinates of the touch location. The raw coordination data is further analyzed and compensated to give the optimized linearity accuracy. The controller utilizes its multi-point linearity compensation function to compensate non-uniformity of the panel. Each panel is calibrated in factory. Its compensation data is stored in EEPROM of the controller in pair with the panel and is used for linearity compensation. The compensated coordinates is then transmitted to the host computer through RS232 or USB interfaces.