Display driving device

A segment driving circuit of a liquid crystal display panel, for effecting a displaying operation by selectively driving a group of common electrodes and a group of segment electrodes of the liquid crystal display panel, the segment driving circuit comprising:

• a display memory for storing display data displayed on said liquid crystal display panel, locations of said display memory being specified by both an X address indicating an address in an X direction of the display panel and a Y address indicating an address in a Y direction of the display panel;
• an address data memory including:
• a write-in address register for storing write-in address data including an X address data and a Y address data for said display memory:
• and
• a readout address register of smaller stgrage capacity than said write-in address register, for storing readout address data including only said Y address data;
• a data write-in circuit for writing data into said display memory according to the X and Y address data stored in said write-in address register;
• a data readout circuit for reading out display data of one line for one common electrode to be supplied to said segment electrode group at one time from said display memory according to the Y address data stored in said smaller storage capacity readout address register;
• a bus for transferring the display data of one line read out from said display memory in a parallel form;
• a segment data memory connected to said bus, for storing display data of one line read out by said data readout circuit;
• and
• a segment signal generation circuit for driving said segment electrode group according to the display data stored in said segment data memory.