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Capacitive Touch Switches: The Ideal Mix of Interface, Algorithm, and Connectivity (.PDF Download)

Sept. 21, 2018
Capacitive Touch Switches: The Ideal Mix of Interface, Algorithm, and Connectivity (.PDF Download)

Take a quick look at most older appliances, consumer products, and even medical devices of just a few decades ago and you’ll see their user front panels are covered with traditional, protruding electromechanical pushbutton-contact switches. In many cases, these pushbuttons are covered to protect them from spilled liquids and dirt, while their labels take up precious panel space.

Now fast-forward to the present and their appearance has dramatically changed, largely due to one development: reliable and cost-effective touch sensing, especially capacitive-based touch sensing. These switches have varying shapes and sizes, with labels and images on overlays on top of the entire panel, and with no openings for liquid or dirt intrusion.

They’re activated when the user’s finger gets close to (proximity) or touches the overlay, depending on the design and implementation specifics. In contrast, using capacitive-touch sensing, there’s no need for or even possibility for physical contact between the switch’s metallic elements and the user’s finger, an additional benefit (Fig. 1).

1. The capacitance-based touch pushbutton is now widely used in consumer products due to its many positive attributes and overall cost-effectiveness.

One key feature of capacitive touch sensing is long-term reliability. There are no moving parts, no exposure to the elements, no required activation force, and no performance changes due to dirt intrusion. Other advances have led to the elimination of additional panel assembly cost, no switches to insert and wire, no need for costly panel cutouts, flexibility of switch location and positioning, and an overall enhanced and sleek appearance.

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