The liquid crystal display device is comprised of a matrix panel 1, a common driver 2 and a segment driver 3. A liquid crystal layer is interposed between rows of the scanning electrodes 4 and columns of signal electrodes 5. A frame memory 6 stores an inputted dot data each frame. An orthonormal signal generator 7 generates a set of orthonormal signals to sequentially feed the same in a desired combination pattern to the common driver 2 to concurrently drive a multiple of the scanning electrodes 4 to effect group sequential scanning according to the combination pattern. A dot product computation unit 8 executes dot product computation between a set of the dot data and the set of the orthonormal signals, the result of which is fed to the segment driver 3 to drive the columns of the signal electrodes 5. The group sequential scanning is repeated several times within one cycle to display a picture. The orthonormal signals are horizontally or vertically shifted to improve the quality of the displayed picture. Further, the multiple concurrent line number is optimized to balance the withstand voltage between the common driver 2 and the segment driver 3. Moreover, in the gray shading display by pulse-height modulation, a voltage pulse assigned to a virtual line of the scanning electrode is spread out to improve the gray shaded quality of the displayed picture.