ORGANIC LIGHT EMITTING DIODE DISPLAY AND DRIVING METHOD THEREOF
An organic light emitting diode (OLED) display and a method of driving the same are provided. The OLED display includes: a plurality of pixels arrayed in a matrix, each of which includes a switching transistor and a driving transistor; a plurality of data lines connected to the switching transistors, which transmit a data voltage to the pixels; a plurality of driving voltage lines that transmit a driving voltage to the driving transistors; a voltage generator that applies the driving voltage to the driving voltage lines; a current sensing unit that senses a driving current that flows from the voltage generator to the driving voltage lines; a gray voltage generator that generates a gray voltage depending on a change in the driving current; and a data driver that converts an input image signal into the data voltage on the basis of the gray voltage and applies the data voltage to the data lines.
1 . An OLED (organic light emitting diode) display comprising:
a plurality of pixels arrayed in a matrix, each of which comprises a switching transistor and a driving transistor;
a plurality of data lines connected to the switching transistors, which transmit a data voltage to the pixels;
a plurality of driving voltage lines that transmit a driving voltage to the driving transistors;
a voltage generator that applies the driving voltage to the driving voltage lines;
a current sensing unit that senses a driving current that flows from the voltage generator to the driving voltage lines;
a gray voltage generator that generates a gray voltage depending on a change in the driving current; and
a data driver that converts an input image signal into the data voltage based on the gray voltage and applies the data voltage to the data lines.
2 . The OLED display of claim 1 , further comprising a signal controller that calculates the change of the driving current by comparing data corresponding to the driving current with data corresponding to a reference current and controls the gray voltage generator on the basis of the change of the driving current.
3 . The OLED display of claim 2 , wherein the signal controller controls the gray voltage generator to maintain a level of the reference gray voltage when the driving current is measured.
4 . The OLED display of claim 2 , wherein the signal controller controls the gray voltage generator to set the reference gray voltage to an initial value when the driving current is measured.
5 . The OLED display of claim 2 , wherein the current sensing unit comprises an analog-to-digital converter that converts a signal related to the driving current into a digital value and transmits the digital value to the signal controller.
6 . The OLED display of claim 2 , wherein the driving current is measured when the same data voltage is applied to the pixels.
7 . The OLED display of claim 6 , wherein the data voltage is a data voltage corresponding to a predetermined gray.
8 . The OLED display of claim 7 , wherein the predetermined gray is the highest gray or an intermediate gray.
9 . The OLED display of claim 2 , wherein the driving current is measured immediately after the OLED display turns on or off.
10 . The OLED display of claim 2 , wherein the driving current is calculated for an input image signal corresponding to each of three colors.
11 . The OLED display of claim 10 , wherein the three colors are red, green, and blue.
12 . The OLED display of claim 1 , wherein as the change in the driving current increases, the reference gray voltage increases.
13 . A method of driving an OLED display comprising a plurality of pixels arrayed in a matrix, a plurality of driving voltage lines connected to the pixels, and a voltage generator that applies a driving voltage to the driving voltage lines, the method comprising steps of:
measuring a driving current that flows between the voltage generator and the driving voltage lines;
calculating a current change by comparing the driving current with a reference current; and
generating a reference gray voltage according to the current change.
14 . The method of claim 13 , wherein as the current change increases, the reference gray voltage increases.
15 . The method of claim 13 , wherein the driving current is measured immediately after the OLED display is turned on or off.
16 . The method of claim 15 , wherein the driving current is measured when the same data voltage is applied to the plurality of pixels.
17 . The method of claim 15 , wherein the data voltage is a data voltage corresponding to the highest gray or an intermediate gray.