Patent ID: 7940286

Claim:
An apparatus comprising: a digital-to-analog converter (DAC); and a circuit to receive pixel data and to generate a first set of reference voltages using resistive elements connected in series during a first time period, the first set of reference voltages being provided to the DAC for generating gray-scale voltages to drive pixel circuits to display respectively different gray-scale levels according to a first gamma profile during the first time period in accordance with the pixel data, generate a second reference voltage or a second set of reference voltages using the series-connected resistive elements during a second time period, the second reference voltage or second set of reference voltages being provided to the DAC for generating a gray-scale voltage or gray-scale voltages to drive the pixel circuits to display a common gray-scale level during the second time period, and generate a third set of reference voltages using the resistive elements during a third time period, the third set of reference voltages being provided to the DAC for generating gray-scale voltages to drive the pixel circuits to display respectively different gray-scale levels according to a second gamma profile during the third time period in accordance with the pixel data; wherein switching among driving the pixel circuits to display respective different gray-scale levels according to the first gamma profile, driving the pixel circuits to display the common gray-scale level, and driving the pixel circuits to display respective different gray-scale levels according to the second gamma profile is responsive to switching among providing the first set of reference voltages to the DAC, providing the second reference voltage or second set of reference voltages to the DAC, and providing the third set of reference voltages to the DAC, and wherein the circuit comprises a first switch, a second switch, and a third switch, and the circuit is configured to turn on the first switch, turn off the second switch, and turn on the third switch to cause a first electric current to flow through the first switch, the series of resistive elements, and the third switch to generate the first set of reference voltages, and the circuit is configured to turn off the first switch, turn on the second switch, and turn on the third switch to cause a second electric current to flow through the second switch, the series of resistive elements, and the third switch to generate the third set of reference voltages.