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How cooktop buttons works? In this picture can see circles (marks) from control board. cooktop glass from inside

Here are control board with buttons. If i touch that black "buttons", it is like dish wash sponge. Control board (part one)

How that buttons works ? Because in glass have no holes or some wires. Those black "buttons" are some special material?

Guntis
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  • Possible duplicate of [Capacitive touch sensors, how do they work?](http://electronics.stackexchange.com/q/47204/14004) and [Sensing touch through a thick surface?](http://electronics.stackexchange.com/q/1253/14004) and [How to make an entire (irregular) surface sense touch with a capacitive sensor?](http://electronics.stackexchange.com/q/25995/14004) and many more. Those black sponge cylinders are most likely a conductive foam / silicone sponge such as sometimes used for packing electronic components. – Anindo Ghosh Jul 18 '13 at 08:19
  • (If they aren't working, before dismantle the device, try to heat the ceramic glass with a hair dryer during 5 seconds, and try again) – JinSnow Dec 23 '18 at 09:52

1 Answers1

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Those black "buttons" are conductive foam, extending a touch sensor's conductive surface to just below the inner surface of the glass.

This allows capacitive touch or capacitive proximity sensors on the PCB, under the conductive foam, to sense touch / finger proximity on the upper side of the glass.

See this answer for some possible touch / proximity sense components, and a description of how they would work through glass.

QTouch

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Anindo Ghosh
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