Gamma voltage generating circuit, source driver and display device including the same

A display device comprising:

• a display panel including a scan line, a data line, and a pixel connected to the scan line and the data line;
• a gate driver configured to supply a scan signal to the scan line;
• and
• a source driver configured to supply a data voltage to the data line,
• wherein the source driver includes:
• a gamma voltage generator configured to generate gamma voltages having voltage levels different from each other in response to a gamma enable signal;
• a digital-to-analog converter configured to generate the data voltage corresponding to a gray scale value using the gamma voltages;
• and
• a source buffer configured to output the data voltage to the data line,
• wherein the gamma voltage generator includes:
• a first resistor string configured to set a voltage range of the gamma voltages;
• a second resistor string configured to set tab gamma voltages corresponding to some of the gamma voltages within the voltage range;
• gamma buffers configured to output the tab gamma voltages;
• and
• a third resistor string including tabs respectively connected to output terminals of the gamma buffers, the third resistor string being configured to divide a voltage between the tabs to generate the gamma voltages,
• wherein a frame period includes a display period in which an image is displayed and a porch period between the display period and another display period,
• wherein the source buffer is turned off in the porch period and is turned on in the display period, and
• wherein at least some of the gamma buffers are turned off during a part of the porch period and are turned on during a rest of the porch period.

A source driver comprising:

• a gamma voltage generator configured to generate gamma voltages having voltage levels different from each other in response to a gamma enable signal;
• a digital-to-analog converter configured to generate a data voltage corresponding to a grayscale value using the gamma voltages;
• and
• a source buffer configured to output the data voltage to a data line,
• wherein the gamma voltage generator includes:
• a first resistor string configured to divide a voltage between a first reference voltage and a second reference voltage;
• a second resistor string configured to divide a voltage between two selected voltages among voltages divided by the first resistor string;
• gamma buffers configured to output some of voltages divided by the second resistor string as tab gamma voltages;
• and
• a third resistor string including tabs respectively connected to output terminals of the gamma buffers, the third resistor string being configured to divide a voltage between the tabs to generate the gamma voltages, and
• wherein the gamma voltage generator, in response to the gamma enable signal, turns on the gamma buffers during a part of a horizontal time and turns off some of the gamma buffers during a rest of the horizontal time, and
• wherein the data voltage is not provided to a pixel in the part of the horizontal time.