How Do Surface Capacitive Touchscreens Work?

Capacitive touchscreens are distinguished from all other types of touchscreens by their use of capacitance to detect touch commands. When turned on, they generate a uniform electrostatic field. They will constantly measure this field while looking for changes in capacitance. If you touch or tap the display interface with a conductive object — or your bare finger for that matter — you’ll change the capacitance. The capacitive touchscreen will then register this change of capacitance as a touch event.

All capacitive touchscreens look for changes in capacitance to determine when and where touch events occur. But there are different types of capacitive touchscreens, one of which is surface capacitive. Surface capacitive touchscreens still produce a uniform electrostatic field, and they still look for changes in capacitance. Surface capacitive touchscreens, however, use a different design than other types of capacitive touchscreens.

Conductive Traces on a Single Side

Surface capacitive touchscreens work by forming a capacitor when a conductive object touches the display interface. More specifically, they feature conductive traces on a single side of this insulator layer. Surface capacitive touchscreens will then apply a voltage to this layer.

The voltage is responsible for creating the touchscreen’s uniform electrostatic field. Al capacitive touchscreens, including surface capacitive, rely on a uniform electrostatic field to detect touch commands. They produce an electrostatic field, which they measure while looking for changes in capacitance. Surface capacitive touchscreens simply feature a conductive traces on a single side of the insulator layer.

The Controller Identifies Touch Commands

Surface capacitive touchscreens feature a controller. The controller’s job is to identify touch commands.

When you touch or tap a surface capacitive touchscreen with a conductive object, you’ll change its capacitance. You’ll inadvertently form a capacitor at the location of your touch command, and the capacitance of the touchscreen will then change as a result. The controller will determine the location of your touch commands so that it can send the correct signal to the touchscreen’s computer.

What About Other Capacitive Touchscreens?

There are other types of capacitive touchscreens. In addition to surface, for instance, there are projected capacitive touchscreens. Also known as PCT and PCAP touchscreens, projected capacitive touchscreens feature a grid of conductive traces.

Projected capacitive touchscreens can further be broken down into the following categories: mutual and self-capacitive. Regardless, most capacitive touchscreens are either surface or projected. Surface capacitive touchscreens feature conductive traces on a single layer, whereas projected capacitive touchscreens feature a grid of conductive traces.