Capacitive Sensing: How It Works in Touchscreens

Aug 11, 2020

Capacitive has become the world’s leading touchscreen technology. Research shows that over nine in 10 touchscreens produced and shipped globally are powered by this technology. Not to be confused with resistive, capacitive is a type of touchscreen technology that uses capacitive sensing to detect touch commands. For a better understanding of capacitive sensing and how it works in touchscreens, keep reading.

What Is Capacitive Sensing?

Capacitive sensing refers to the measurement of an otherwise uniform electrostatic field. It’s based on the principle of capacitive coupling, meaning that anything with electrically conductive properties can be measured. When two conductive objects are placed together, they’ll share some of their electrical charge. Capacitive sensing involves the measurement of an object’s electrical charge.

How Capacitive Sensing Works in Touchscreens

Capacitive touchscreens use capacitive sensing to detect touch commands. While invisible to the naked eye, capacitive touchscreens produce a uniform electrostatic field during operation. The electrostatic field runs through the capacitive touchscreen’s top layer — and it’s measured by an underlying touchscreen controller.

Normally, the electrostatic field remains consistent. It doesn’t increase, nor does it decrease. When you touch or tap the top layer, however, the electrostatic field will change. As you may know, the human body is an excellent conductor of electricity. Capacitive touchscreens leverage the human body’s conductive properties to detect touch commands. Touching or tapping the top layer creates a distortion in the capacitive touchscreen’s electrostatic field at the point of your touch command. The underlying touchscreen controller will then register this distortion as a touch command.

All capacitive touchscreens use capacitive sensing. After all, that’s why they are known as “capacitive” touchscreens. Capacitive sensing allows these touchscreens to detect touch commands by looking for changes in the electrostatic charge that’s projected through the top layer.

Benefits of Capacitive Sensing

Capacitive sensing offers several benefits when used in touchscreens. For starters, it offers a high level of responsiveness — more so than other touchscreen technologies. You don’t have to forcefully press or tap the top layer of a capacitive touchscreen to perform a touch command. In many cases, hovering your finger over the top layer will cause a distortion in the device’s electrostatic field and, therefore, trigger a touch command.

Not only are they are responsive, but capacitive touchscreens also offer excellent image clarity. The top layer is typically made of glass. Unlike plastic, glass has excellent clarity. More of the light produced by the device’s backlighting can show through the glass layer. The end result is clearer and higher-quality images when compared to other touchscreen technologies.

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