Abstract: In order to attain an electric power saving for a liquid crystal display having a pre-charging unit, a signal line driving circuit according to the present invention is used in an active matrix type of a liquid crystal display, and it is characterized in that it applies a middle potential Vp serving as a pre-charging voltage and a gradation voltage corresponding to a picture data to a plurality of signal lines, and it has a latch 11 and a comparator 12 for comparing a picture data before one horizontal period with a picture data to be next displayed for each signal line, and a switch controller 13 for applying the middle potential Vp in accordance with the result compared by the comparator 12, and if a writing operation can be stably carried out at a high speed without any pre-charging operation, the pre-charging operation is not done. Thus, it is possible to reduce a loss of a current necessary for the pre-charging operation.

Abstract: In order to attain an electric power saving for a liquid crystal display having a pre-charging unit, a signal line driving circuit according to the present invention is used in an active matrix type of a liquid crystal display, and it is characterized in that it applies a middle potential Vp serving as a pre-charging voltage and a gradation voltage corresponding to a picture data to a plurality of signal lines, and it has a latch 11 and a comparator 12 for comparing a picture data before one horizontal period with a picture data to be next displayed for each signal line, and a switch controller 13 for applying the middle potential Vp in accordance with the result compared by the comparator 12, and if a writing operation can be stably carried out at a high speed without any pre-charging operation, the pre-charging operation is not done. Thus, it is possible to reduce a loss of a current necessary for the pre-charging operation.