Patent ID: 8416175

Claim:
A liquid crystal display device comprising: a liquid crystal panel including a plurality of pixel rows that display an image; a plurality of pixel cells arranged in each of the pixel rows; a common electrode provided in common in the pixel cells; a common voltage correction unit that obtains predominant-polarity data based on polarities of image data to be supplied to the pixel cells arranged in an nth one of the pixel rows, obtains predominant-polarity data based on polarities of image data to be supplied to the pixel cells arranged in an (n+1)th one of the pixel rows adjacent to the nth pixel row, obtains a sum of the two predominant-polarity data, and selects and outputs any one of a plurality of predetermined correction values based on the sum; and a common voltage output unit that corrects a common voltage based on the correction value from the common voltage correction unit and supplies the corrected common voltage to the common electrode; wherein the common voltage correction unit comprises: a polarity separator that sequentially receives image data externally supplied thereto on a pixel row basis, and, whenever image data corresponding to pixel cells in one pixel row is received, separates the received image data into positive image data and negative image data and outputs the separated positive image data and negative image data; a predominant polarity calculator that calculates a sum of the positive image data and negative image data from the polarity separator to output predominant-polarity data; a register that sequentially stores two predominant-polarity data sequentially inputted from the predominant polarity calculator in the inputted order, and updates an earlier stored one of the sequentially stored two predominant-polarity data to predominant-polarity data inputted subsequently to the stored two predominant-polarity data; a deviation calculator that calculates a sum of the two predominant-polarity data stored in the register to output deviation data; a lookup table including the plurality of predetermined correction values by deviation data; and a correction value output unit that receives the deviation data from the deviation calculator, selects a correction value corresponding to the received deviation data from the correction lookup table and provides the selected correction value to the common voltage output unit.