Patent ID: 6882329
Filing Date: 2005-04-19
Classification: G09G

Abstract:
1. A drive signal generation circuit which performs gradation control on a load by a drive signal having a stepped waveform, the drive signal being obtained by performing wave height-value modulation and pulse width modulation in combination using a multistage potential source (V(n−1)<Vn) having a potential range from V 1 to Vn (n: an integer equal to or larger than 2), and in which if the wave height value corresponding to input gradation data is Vm (2≦m≦n; m: an integer), the drive signal is caused to rise in such a manner that each output Vk (2≦k≦m; k: an integer) is produced one slot after the output V(k−1) to increase the wave height value from off level to Vm in a stepping manner, one slot corresponding to a unit time of the pulse width modulation, and the drive signal is caused to fall in such a manner that each output V(k−1) (1≦k≦m−1) is produced one or two slots after the output Vk to reduce the wave height value from Vm to off level in a stepping manner, said drive signal generation circuit comprising: a start pulse output circuit for generating a pulse with which a start of the output V an end pulse output circuit which outputs a pulse with which an end of the output Vm is synchronized; a first delay circuit which produces a plurality of delayed outputs by successively delaying one slot at a time the pulse with which the start of the output V a second delay circuit which produces a plurality of delayed outputs by successively delaying in one-slot steps the pulse with which the end of the output Vm is synchronized; a circuit which generates the pulse with which the start of the output V a pulse width generation circuit which produces a pulse width signal of each output Vk (1≦k≦n) by the control signal.