Projected capacitive has become one of the world’s leading touchscreen technologies. It’s a variant of capacitive touchscreen technology. Like all capacitive touchscreens, projected capacitive touchscreens measure an electrostatic field to detect touch commands. When you tap or touch the surface, your finger will absorb some of its electrostatic field.
Projected capacitive touchscreens, however, are more sensitive to touch commands than other types of capacitive touchscreens. They feature a grid of conductive traces that allows them to detect more touch commands more accurately. While available in different sizes and specifications, most projected capacitive touchscreens feature a few basic parts.
Sensor Glass
The sensor glass is a layer of glass that features electrodes in the form of a conductive coating. As the name suggests, it’s responsible for “sensing” touch commands. The sensor glass has rows and columns of conductive traces.
When a projected capacitive touchscreen is turned on, it will produce an electrostatic field that travels through these conductive traces. The conductive traces create a sensing grid. Performing a touch command will draw some of the device’s electrostatic field to your finger from the nearest conductive traces of the sensor glass.
Cover Glass
The cover glass is another essential part of a projected capacitive touchscreen. It serves as the dielectric between the user’s finger and the conductive traces of the sensor glass. The cover glass is the uppermost layer of a projected capacitive touchscreen. You won’t actually touch the sensor glass when using a projected capacitive touchscreen. Rather, you’ll touch the cover glass.
In addition to serving as the dielectric between the user’s finger and the sensor glass’s conductive traces, the cover glass protects the projected capacitive touchscreen from environmental contaminants. It forms a barrier over the top of the projected capacitive touchscreen. With the cover glass, moisture, dust and other environmental contaminants won’t be able to enter the projected capacitive touchscreen.
FPC
All projected capacitive touchscreens require a circuit, the most common of which is a flexible printed circuit (FPC). The conductive traces of the sensor glass connect to the FPC. Unlike rigid circuits, FPCs are flexible. They can flex and bend without breaking, making them ideal for small touchscreens. Regardless, most projected capacitive touchscreens feature a sensor glass, cover glass and FPC.
The FPC serves as the controller. Touchscreens require a controller so that they can convert analog touch signals into digital touch signals. Whether it’s a projected capacitive touchscreen, a surface capacitive touchscreen or even a resistive touchscreen, the controller is typically found in the FPC.
