Liquid crystal display device and its drive method and the drive circuit and power supply circuit device used therein

Abstract

Liquid crystal display device and its drive method that applies the voltage of the difference of a scanning signal and a data signal having at least a reset period, a selection period and a non-selection period in one frame on a chiral nematic liquid crystal having at least two stable states. A total of eight voltage levels made up of a plurality of levels (V,, V,, V,, V,) of a first group on the low voltage side and a plurality of levels (V,, V,, V,, V,) of a second group on the high voltage side are provided. The voltage levels of scanning signal Yi and data signal Xj are alternated between the first group and second group every mH (where, m is an integer that is 2 or greater and H≠1 frame period), which is an integral multiple of the unit time (1H) equivalent to the selection period T,of scanning signal Yi. When the data signal (Xj) is a voltage level of the first group, the voltage level of the reset period (T,) in the scanning signal (Yi) is selected from the second group, and when the data signal (Xj) is a voltage level of the second group, the voltage level of the reset period (T,) in the scanning signal (Yi) is selected from the first group. When the data signal (Xj) is a voltage level of the first group, the voltage levels of the selection period (T,) and non-selection period (T,) in the scanning signal (Yi) are each selected from the same first group, and when the data signal is a voltage level of the second group, the voltage levels of the selection period (T,) and non-selection period (T,) in the scanning signal (Yi) are each selected from the same second group. By this means, the polarity of the voltage applied to the liquid crystal is reversed every mH.