Patent ID: 7714746

Claim:
An apparatus for identifying a key switch operation comprising: a key switch matrix circuit comprising a plurality of key switches arranged in rows and columns, each row having a scan line, each column having a sense line and each key switch operable to couple a scan line to a sense line; a scan signal delivery circuit coupled to the scan lines of the switch matrix circuit and operable to supply scan signals to rows of the key switch matrix circuit via the scan lines, the scan signals delivering a scan pulse to each row of the key switch matrix circuit in turn; a key switch detection circuit coupled to the sense lines of the switch matrix circuit and to the scan signal delivery circuit, the key switch detection circuit key operable to output a first signal if a key switch of the plurality of key switches is operated; and a scan pulse detection circuit, coupled to the sense lines of the switch matrix circuit and to the scan signal delivery circuit, operable to output a second signal if a scan pulse is coupled to a sense line; wherein the scan signal delivery circuit is operable to begin supplying scan signals in response to the first signal and to stop supplying scan signals in response to the second signal.