Patent ID: 8223105

Claim:
A liquid crystal display (LCD) controller comprising: a plurality of segment/key source control circuits connected with an LCD panel and a key matrix through a plurality of segment/key source terminals, to periodically output a signal for one frame which contains a display output period and a key source output period, wherein each of said plurality of segment/key source control circuits: outputs a segment signal to a corresponding one of said plurality of segment/key source terminals during the display output period, wherein the segment signal has a display drive voltage indicating a maximum value, a minimum value, and intermediate values between the maximum value and the minimum value, and outputs a first key scan pulse signal varying between the maximum value and the minimum value to a corresponding one of said plurality of segment/key source terminals during the key source output period in a key scan state when said key matrix has been operated, and then, outputs a second key scan pulse signal obtained by inverting the first key scan pulse signals to the corresponding segment/key source terminal.