Projected Capacitive Touch

Touch Screen

PCAP Touch is built up by using different conductive materials such as Indium Tin Oxide (ITO) or metallic wires placed in form of a grid in layers on sheets of plastic film.

The films are then laminated on the backside of a front glass.

When a voltage is applied to the grid a uniform electrostatic field is created. The electrostatic field reaches through the front glass and when it is interfered by a conductive object such as a human finger or conductive stylus it will be distorted. The distortion can be detected by a controller circuit which will calculate the position.

The front glass can be customized in many ways. For example a screen print can be applied to cover areas outside the active touch area. Other things that can be customized are the shape of the glass, the thickness of the glass, the form of the chamfers, the location of the tails or applying anti-glare treatment or anti-reflective films to the glass.

For smaller sizes the touch controller often comes as Chip-On-Film (COF) and for larger sizes as a separate printed circuit board.