Patent ID: 7307610

Claim:
A display driving device for applying, to data signal lines of an active matrix display panel, a tone display voltage inverted in polarity at a predetermined cycle and modulated in accordance with display data, said display driving device comprising: a tone voltage generator for generating as many standard voltages as tones, a selector circuit for selecting a group of standard voltages from two groups of the generated standard voltages, and a digital-to-analog converter for selecting one of the standard voltages in the group in accordance with display data and outputting the selected standard voltage as a tone display voltage, the tone voltage generator comprising, a standard voltage generator for generating as many standard voltages as tones, the standard voltages having voltage values between an upper limit voltage and a lower limit voltage, and an upper/lower limit voltage generator for generating the upper limit voltage and the lower limit voltage, wherein the standard voltage generator generates as many standard voltages as tones using or based on the upper and lower limit voltage generated by the upper/lower limit voltage generator, the upper/lower limit voltage generator is arranged to be fed with an input voltage regulated by an external voltage regulator and to vary both the upper limit voltage and the lower limit voltage in accordance with an identical input voltage, and the two groups have polarities opposite to each other.