Apparatus and method for controlling gray level for display panel

A method for controlling a gray level for a display panel driven by a plurality of scan line signals and a plurality of data line signals comprising the steps of:

• a) externally inputting a data value corresponding to the gray level for the display panel;
• b) dividing the input data value into bits of first and second groups;
• c) either pulse width modulating the bits of the second group after pulse amplitude modulating the bits of the first group or pulse amplitude modulating the bits of the second group after pulse width modulating the bits of the first group;
• and
• d) inputting the modulated data value to a corresponding data line to control the gray level for the display panel.

An apparatus for controlling a gray level for a display panel driven by a plurality of scan line signals and a plurality of data line signals comprising:

• a pulse modulation part for pulse amplitude modulating some of bits of externally input data corresponding to the gray level for the display panel and pulse width modulating the other bits to apply them to the data lines;
• a switch part for switching the pulse modulated data of the data lines in accordance with the scan line signals;
• and
• a drive part for controlling the gray level for the display panel corresponding to the data applied from the switch part to drive the display panel.