I ripped open my usb keyboard as it was not working inorder to learn and try fixing it.
when the keys are pressed a contact is made between two electrode points below the key (the white sheet of plastic with lots of lines actually has 3 layers of plastic, with two on outer side having conducting stuff just below the key and a middle neutral layer of plastic sheet in order to avoid contact between the electrode unless a key is presed)
the information is then transferred to a small electronic chip from which the wore connects the keyboard either to ps/2 port or the usb port.
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| plastic sheet with lots of printed conducting lines. has 3 layers |
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| Juction between plastic membrane and the circuit. |
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| the circuit visible after removing the membrane. |
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| the keys with circuit on top left corner. |
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| close up of keys. Each key has a central hard portion to press against the membranes in order to generate a signal. |
