Capacitive touchscreen technology typically falls under one of two categories: surface capacitance or projected capacitance. Both technologies have been around for decades. And although they’ve gone through a variety of changes since their inception, surface and projected capacitance rely on the conductive properties of the human body to identify touch. When you touch the surface of either a surface or projected capacitance touchscreen device, your finger absorbs some of the device’s electrostatic charge, thereby allowing the device to identify the location of your touch command. There’s only a single type of surface capacitance technology, but there are actually two separate types of projected capacitance, which we’re going to explore in this blog post.
One of the two types of projected capacitance touchscreen technology is mutual capacitance. Touchscreen devices featuring this technology are characterized by a unique design in which a row trace and column trace intersect to create a capacitor. The rows and columns are essentially formed to create a grid, and the intersecting points of these grids function as capacitors. Mutual capacitance devices are able to support multiple simultaneous touches as a result of this design. Also known as multi-touch, it’s become a common and highly sought-after feature of touchscreen devices. Pinch-to-zoom, for example, is a multi-touch command that allows users to zoom in or out of their touchscreen device’s display by pinching the screen.
The other type of projected capacitance touchscreen technology is known as self-capacitance. Self-capacitance touchscreen devices often feature the same grid-like array of electrodes. The difference between self-capacitance and mutual capacitance, however, is that the former measures the user’s capacitance — electrical charge — using a current meter. Each capacitor in self-capacitance touchscreen devices operate independently of each other. This design offers a higher level of sensitivity than mutual capacitance
Which One Is Best?
There’s no single best choice between mutual or self-capacitance touchscreen technology. With that said, many users prefer self-capacitance for buttons and switches because of its simple, reliable design. For touchscreen devices like smartphones and tablets, mutual capacitance is preferred because of its ability to support multiple simultaneous points of contact. There’s also resistive touchscreen technology, which is a completely different form of touchscreen technology that relies on pressure to identify touch commands. When choosing a touchscreen device, consider the touch-sensing technology powering it. Depending on your intended application, mutual or self-capacitance technology may offer the highest level of utility. In others, resistive may be preferred.