Projected capacitive Touch screens.

Obeytec Projected capacitive touch screen (PCAP touch screen or PCT touch screen) technology is a variant of capacitive touch technology but where sensitivity to touch, accuracy, resolution, and speed of touch have been greatly improved by the use of a simple form of “Artificial Intelligence”. This intelligent processing enables finger sensing to be projected, accurately and reliably, through very thick glass and even double glasses.

Obeytec some new model PCAP touch screens are composed of thousands of discrete keys, but most PCAP touch screens are made of a matrix of rows and columns of conductive material, layered on sheets of glass. This can be done either by etching a single conductive layer to form a grid pattern of electrodes or by etching two separate, perpendicular layers of conductive material with parallel lines or tracks to form a grid. In some designs, the voltage applied to this grid creates a uniform electrostatic field, which can be measured. When a conductive object, such as a finger, comes into contact with a PCAP panel, it distorts the local electrostatic field at that point. This is measurable as a change in capacitance. If a finger bridges the gap between two of the “tracks”, the charge field is further interrupted and detected by the controller. The capacitance can be changed and measured at every individual point on the grid. This system can accurately track touches.

Due to the top layer of a PCAP touch sensor being glass, it is sturdier than less-expensive resistive touch technology. Unlike traditional capacitive touch technology, a PCAP system can sense a passive stylus or gloved finger. However, moisture on the surface of the panel, high humidity, or collected dust can interfere with performance. These environmental factors, however, are not a problem with ‘fine wire’ based touchscreens because wire based touchscreens have a much lower ‘parasitic’ capacitance, and there is a greater distance between neighboring conductors.

Projected capacitive Touch screens Drawing Download