Many people assume that all capacitive touchscreen devices use the same technology to detect touch commands. Whether it’s a smartphone, tablet, human machine interface (HMI) or any other touchscreen device, if it’s powered by capacitive technology, it will detect touch commands by measuring capacitance. If the device’s capacitance drops, it will read and register this voltage reduction as a touch command. There are different types of capacitive touchscreens, however, the most common of which include projected capacitive and surface capacitive. So, what’s the difference between projected and surface capacitive touchscreens?
What Is Surface Capacitive?
The most common type of capacitive touchscreen technology, surface capacitive is characterized by the use of a single conductive layer on one side of the insulator panel. Surface capacitive touchscreens apply a small voltage to this layer, thus resulting in the formation of a uniform electrostatic field. When a conductive object, such as a capacitive stylus or even a human finger, touches the insulated the layer, the voltage drops.
Most surface capacitive touchscreens utilize a transparent electrode film. The electrode film is placed on the underside of the device’s insulator layer. When you touch a surface capacitive device using any conductive object, the voltage created by the electrode film drops.
What Is Projected Capacitive?
Like surface capacitive, projected capacitive is a type of touchscreen technology that detects touch commands by measuring capacitance. Both types of touchscreen technology create a uniform electrostatic field that, when touched, results in a lower voltage. With that said, projected capacitive differs in a few key ways.
The primary difference between projected capacitive and surface capacitive touchscreens is that the latter uses two layers of electrodes whereas the former uses a single layer of electrodes. Although there are numerous ways to design and configure a projected capacitive touchscreen, most feature columns and rows of intersecting electrodes. One of the two layers features rows of electrodes, while the other layer features columns of electrodes. When placed together, the two layers create a grid-like formation of intersecting electrodes.
Because of their unique design featuring intersecting electrodes, projected capacitive touchscreens are more responsive to touch commands than their surface capacitive counterparts. Many projected capacitive touchscreens, in fact, will register touch commands through thin gloves — a feature that’s not found in surface capacitive touchscreens.
Furthermore, only projected capacitive touchscreens support multi-touch commands. With that said, projected capacitive touchscreens typically cost more than surface capacitive touchscreens, which may deter some consumers and business owners from choosing them.