Patent ID: 7317642

Claim:
An overdrive period control device comprising: a pre-charge circuit connected to a node on which a potential level is detected and for raising a potential at the node to a first potential; a delay element one terminal of which is connected to the node; a charge circuit for supplying a power source voltage to the other terminal of said delay element at an input timing of a signal from an outside and for raising the potential at the node, which has been already raised to the first potential, to the power source voltage; a comparison circuit for comparing the potential at the node with a reference potential that is larger than the first potential and smaller than the power source voltage and for detecting a timing at which both levels of the potentials coincide; and a logic circuit outputting a signal indicating a period determined by the input timing of the signal from the outside and the timing in which said comparison circuit detects that both levels of the potentials coincide.