Patent ID: 7659875
Filing Date: 2010-02-09
Classification: G09G

Abstract:
1. A gradation display reference voltage generating circuit for generating reference voltages for gradation display used for digital-to-analog conversion of display data, comprising: a first reference voltage producing section for producing a plurality of first reference voltages for positive polarity drive with respect to a reference potential of a displaying object; a second reference voltage producing section for producing a plurality of second reference voltages for negative polarity drive which are opposite in polarity to the plurality of first reference voltages produced by the first reference voltage producing section; a plurality of reference voltage outputs for outputting the plurality of first reference voltages from the first reference voltage producing section at the positive polarity drive, while outputting the plurality of second reference voltages from the second reference voltage producing section at the negative polarity drive, said first reference voltage producing section comprising a first ladder resistor circuit in which a plurality of first resistance elements are connected in series between two different power supplies and which produces the plurality of first reference voltages by resistance division of a difference in voltage between the two power supplies by the plurality of first resistance elements, and said second reference voltage producing section comprising a second ladder resistor circuit in which a plurality of second resistance elements are connected in series between the two power supplies and which produces the plurality of second reference voltages by resistance division of the difference in voltage between the two power supplies by the plurality of second resistance elements; and a short-circuit section for establishing short circuits between adjacent ones of the plurality of reference voltage outputs during a predetermined short-circuit period upon switching between the positive polarity drive and the negative polarity drive.