Organic light emitting display and method of driving the same

An organic light emitting display comprising:

• a plurality of pixels, each pixel comprising an organic light emitting diode and a pixel circuit for controlling a supply of an electric current to the organic light emitting diode;
• and
• a sensing unit for supplying a first current to the organic light emitting diode in each of the pixels and converting a voltage applied to the organic light emitting diode to a respective one of digital values during a sensing period, and for sinking a second current from each of the pixels corresponding to the respective one of the digital values to compensate for a degradation of the organic light emitting diode during a sampling period,
• wherein the sensing unit comprises:
• a current source unit for supplying the first current;
• a current digital-analog converter for sinking the second current;
• a switching unit for selectively coupling the current source unit and the current digital-analog converter to a feedback line among a plurality of feedback lines;
• an analog-digital converter coupled to the current source unit for converting a voltage applied to the organic light emitting diode to the respective one of the digital values;
• a memory for storing the digital values;
• and
• a controller for controlling an amount of the second current sunk by the current digital-analog converter corresponding to the respective one of the digital values stored in the memory,
• wherein each of the feedback lines is coupled to at least one pixel among the plurality of pixels, and
• wherein the current digital-analog converter comprises:
• a current generator for generating a third current and a fourth current, the third current and the fourth current each corresponding to a current to flow to the organic light emitting diode before the organic light emitting diode is degraded;
• a first sink unit for sinking a fifth current from the feedback line corresponding to the third current supplied by the current generator;
• and
• a second sink unit for sinking a sixth current in accordance with the degradation of the organic light emitting diode from the feedback line and based on the fourth current supplied by the current generator.

An organic light emitting display comprising:

• a plurality of pixels, each pixel comprising an organic light emitting diode and a pixel circuit for controlling a supply of an electric current to the organic light emitting diode;
• a sensing unit for supplying a first current to the organic light emitting diode in each of the pixels and converting a voltage applied to the organic light emitting diode to a respective one of digital values during a sensing period, and for sinking a second current from each of the pixels corresponding to the respective one of the digital values to compensate for a degradation of the organic light emitting diode during a sampling period;
• a data driver for supplying a first data signal and a second data signal to data lines coupled to the pixels, the first data signal for causing the pixels to be emitted and the second data signal for causing the pixels not to be emitted;
• a scan driver for supplying a first scan signal and a second scan signal to first scan lines and second scan lines coupled to the pixels, respectively;
• and
• a control line driver for supplying a control signal to control lines, which are coupled to the pixels,
• wherein the sensing unit comprises:
• a current source unit for supplying the first current;
• a current digital-analog converter for sinking the second current;
• a switching unit for selectively coupling the current source unit and the current digital-analog converter to a feedback line among a plurality of feedback lines;
• an analog-digital converter coupled to the current source unit for converting a voltage applied to the organic light emitting diode to the respective one of the digital values;
• a memory for storing the digital values;
• and
• a controller for controlling an amount of the second current sunk by the current digital-analog converter corresponding to the respective one of the digital values stored in the memory,
• wherein one frame is divided into a plurality of sub frames, and the sampling period is an initial period located at the beginning of the one frame,
• wherein each of the feedback lines is coupled to at least one pixel among the plurality of pixels, and
• wherein each of the pixels comprises:
• a second transistor coupled to the feedback line, and turned on when the scan signal is supplied to a corresponding first scan line among the first scan lines;
• a first transistor having a gate electrode coupled to a second electrode of the second transistor and for supplying an electric current to the organic light emitting diode;
• a first capacitor between the gate electrode and a first electrode of the first transistor, and charged with a voltage corresponding to the second current;
• a third transistor between a second electrode of the first transistor and the feedback line, and turned on when the scan signal is supplied to the corresponding first scan line among the first scan lines;
• a fourth transistor between the first transistor and the organic light emitting diode;
• a second capacitor between the fourth transistor and the first electrode of the first transistor, and charged with a voltage corresponding to the first data signal or the second data signal;
• a fifth transistor between the fourth transistor and the data line, and turned on when the scan signal is supplied to a corresponding second scan line among the second scan lines;
• and
• a sixth transistor between an anode electrode of the organic light emitting diode and the feedback line, and turned on when the control signal is supplied to the control lines.

A method of driving an organic light emitting display, the method comprising:

• supplying a first current via first current paths to organic light emitting diodes included in pixels during a sensing period;
• supplying data signals from a data driver to the pixels;
• converting voltages applied to the organic light emitting diodes corresponding to the first current to digital values and storing the digital values in a memory;
• sinking a second current via second current paths, the second current being sunk in a sensing unit and received from the pixels using the digital values stored in the memory during a sampling period so that a degradation of the organic light emitting diodes is compensated;
• and
• charging the pixels with a voltage corresponding to the second current while sinking the second current in the sensing unit.