How It Works
As can be seen from the diagram below, the membrane keyboard basically consists of three layers; two of these are membrane layers containing conductive traces. The center layer is a "spacer" containing holes wherever a "key" exists. It keeps the other two layers apart.
Under normal conditions, the switch (key) is open, because current cannot cross the non-conductive gap between the traces on the bottom layer. However, when the top layer is pressed down (with a finger), it makes contact with the bottom layer. The conductive traces on the underside of the top layer can then bridge the gap, allowing current to flow. The switch is now "closed", and the parent device registers a keypress.
Typical applications include;
- Industrial controls
- Access control systems
- Medical equipment
- Telecommunications apparatus
- Telephone systems
- Household appliances
- Security systems
Source, APEM, Membrane switch panels
Read more about this topic: Membrane Keyboard
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