What Is a Capacitive Wheel and How Does It Work?

Capacitive technology isn't limited to touchscreens. There are other types of control interfaces that leverage this technology. Keypads and circuits, for instance, may leverage capacitive technology. Some of them feature a capacitive wheel. Capacitive wheels may look like ordinary mechanical dials, but they use a completely different method of operation. What is a capacitive wheel, and how does it work exactly?

The Basics of Capacitive Wheels

Capacitive wheels are touch-based control dials. As previously mentioned, they are commonly found on keypads and circuits.

Both rigid circuits and Flexible Printed Circuits (FPCs) may feature one or more capacitive wheels. Turning a capacitive wheel to the right or left will control the device with which the keypad or circuit is used. Capacitive wheels, however, only require touch-based turning.

How Capacitive Wheels Work

You don't have to physically turn a capacitive wheel to control the connected device. Like capacitive touchscreens, capacitive wheels are touch based. They respond to touch - specifically touch involving a conductive object. As you rotate your finger around a capacitive wheel, it will respond.

Capacitive wheels respond to conductive touches. A voltage will be applied to the surface of a capacitive wheel. Touching this surface with a conductive object will absorb some of this voltage. The capacitive wheel will then respond with the appropriate action.

Of course, you can only control a capacitive wheel with a conductive object. The human body has excellent conductive properties, so you can control a capacitive wheel with a bare finger. You can also control it with a capacitive stylus. Capacitive styluses are pen-like devices that feature a conductive tip. They are designed specifically for capacitive control interfaces, such as capacitive touchscreens and capacitive wheels.