Organic light emitting display device and driving method for the same

An organic light emitting display device, comprising:

• a pixel unit that displays an image by receiving a data signal, a scan signal, a first pixel power, and a second pixel power;
• a regulator that receives first input voltage from the outside and boosts the received first input voltage to generate the first pixel power and inverts the received first input voltage to generate second pixel power;
• a driver driving unit that includes a power generator receiving second input voltage from the outside to generate the first pixel power and the second pixel power and first driving power and second driving power and gray scale voltage and a signal generator generating the data signal and the scan signal;
• a switching unit that selectively connects the pixel unit with the regulator or the pixel unit with the driver driving unit;
• and
• a control unit that transmits the first pixel power and the second pixel power generated by the regulator or the driver driving unit to the pixel unit and controls a number of a plurality of voltages generated by the gray scale voltage generator to be less than the number of plural gray scale voltages generated by the regulator when the first pixel power and the second pixel power are generated by the driver driving unit.