Capacitively coupled keypad structure

An exchangeable cover for a mobile telecommunication device, comprising:

• a keypad that comprises activatable keys,
• first capacitive coupling means for capacitively obtaining an electric input signal to the keypad from an external input signal source,
• second capacitive coupling means for capacitively providing an output signal from the keypad to an external signal detector, and
• between said first capacitive coupling means and said second capacitive coupling means signal conversion means for responding to a key activation by selectively converting an electric input signal into an electric output signal the value of which depends on the activated key.

A set of exchangeable covers for a mobile telecommunication device, comprising:

• a first cover and a second cover,
• within each of said first and second covers means for mechanically attaching the cover to the same mobile telecommunication device,
• within each of said first and second covers a keypad that comprises activatable keys,
• within each of said first and second covers first capacitive coupling means for capacitively obtaining an electric input signal to the keypad from an external input signal source,
• within each of said first and second covers second capacitive coupling means for capacitively providing an output signal from the keypad to an external signal detector,
• within each of said first and second covers signal conversion means for responding to a key activation by selectively converting an electric input signal into an electric output signal the value of which depends on the activated key;
• and
• wherein the first cover has the keys of the keypad at different locations than the second cover.

An electronic device, comprising:

• a keypad that comprises activatable keys,
• an outer cover part,
• a printed circuit board,
• input signal generating means for generating an input signal to the keypad,
• signal conversion means for responding to a key activation by selectively converting the input signal into an output signal the value of which depends on the activated key, and
• output signal detection means for detecting the value of the output signal;
• wherein:
• the input signal generating means and the output signal detection means are located within the printed circuit board,
• the signal conversion means are attached to the outer cover part, and
• the electronic device comprises a first capacitive coupling between the input signal generating means and the signal conversion means, and a second capacitive coupling between the signal conversion means and the output signal detection means.