Signal line driving circuit for an LCD display

A signal line drive circuit for an LCD having multiple lines of pixels arranged in columns, each pixel being coupled to a gate line terminal for receiving an activating voltage for the pixel, a common voltage terminal, and a signal line terminal for receiving an analog gray-scale voltage relative to the common voltage terminal for specifying the brightness of that pixel, said signal line drive circuit comprising for adjacent paired columns of the display:

• a common terminal for coupling to the LCD's common voltage terminal;
• first and second gray scale data terminals for receiving first and second digital gray-scale signals;
• first and second D/A conversion circuits for common coupling to neighboring first and second signal line terminals of the LCD, for respectively generating positive and negative analog gray-scale voltages;
• and
• a first switching circuit for cycling the first and second D/A conversion circuits between
• a first operation, in which the first D/A conversion circuit generates a positive gray-scale voltage responsive to the first gray-scale data at the same time the second D/A conversion circuit generates a negative gray-scale voltage responsive to the second gray-scale data, and
• a second operation, in which the first D/A conversion circuit generates a positive gray-scale voltage responsive to the second gray-scale data at the same time the second D/A conversion circuit generates a negative gray-scale voltage responsive to the first gray-scale data;
• and
• a second switching circuit coupling an output of the first D/A conversion circuit to a first of the adjacent columns of the display and an output of the second D/A conversion circuit to a second of the adjacent columns of the display in the first operation, the second switching circuit coupling the output of the first D/A conversion circuit to the second of the adjacent columns of the display and the output of the second D/A conversion circuit to the first of the adjacent columns of the display in the second operation.