Organic light emitting display

Patent metadata

Field	Value
Publication number	US-9495909-B2
Application number	US-201414533937-A
Country	US
Kind code	B2
Filing date	Nov 5, 2014
Priority date	Dec 30, 2013
Publication date	Nov 15, 2016
Grant date	Nov 15, 2016

Abstract

An organic light emitting display includes a display panel including display lines, on which a plurality of pixels each including an organic light emitting diode and a driving thin film transistor (TFT) are formed. The display lines are sequentially charged to an image display data voltage in response to an image display gate pulse in an image display period of one frame. A sensing target display line among the display lines outputs a sensing voltage corresponding to changes in electrical characteristic of the driving TFT included in each pixel in response to a sensing gate pulse during a vertical blank period excluding the image display period from the one frame and then is charged to a luminance recovery data voltage. The sensing gate pulse is supplied in the same pulse shape as the image display gate pulse in a predetermined period for charging the luminance recovery data voltage.

First claim

What is claimed is:

1. An organic light emitting display comprising:
a display panel including display lines, on which a plurality of pixels each including an organic light emitting diode and a driving thin film transistor (TFT) are formed, the display lines being sequentially charged to an image display data voltage in response to an image display gate pulse in an image display period of one frame, a sensing target display line among the display lines outputting a sensing voltage corresponding to changes in electrical characteristic of the driving TFT included in each pixel in response to a sensing gate pulse during a vertical blank period excluding the image display period from the one frame and then being charged to a luminance recovery data voltage;
a gate driving circuit configured to sequentially supply the image display gate pulse to gate lines connected to the pixels of the display lines during the image display period and supply the sensing gate pulse to a gate line connected to the pixels of the sensing target display line during the vertical blank period; and
a data driving circuit configured to supply the image display data voltage to data voltage supply lines connected to the pixels of the display lines in synchronization with the image display gate pulse and supply the luminance recovery data voltage to data voltage supply lines connected to the pixels of the sensing target display line in synchronization with the sensing gate pulse,
wherein the sensing gate pulse is supplied in the same pulse shape as the image display gate pulse in a predetermined period for charging the luminance recovery data voltage.

2. The organic light emitting display of claim 1 , wherein each pixel includes:
the driving TFT including a gate electrode connected to a first node, a source electrode connected to a second node, and a drain electrode connected to an input terminal of a high potential driving voltage;
the organic light emitting diode connected between the second node and an input terminal of a low potential driving voltage;
a storage capacitor connected between the first node and the second node;
a first switch TFT connected between one of the data voltage supply lines and the first node; and
a second switch TFT connected between a reference line, to which the sensing voltage is output, and the second node.

3. The organic light emitting display of claim 2 , wherein the image display gate pulse includes a first image display gate pulse for turning on the first switch TFT in the image display period and a second image display gate pulse for turning on the second switch TFT in the image display period,
wherein the sensing gate pulse includes a first sensing gate pulse for turning on the first switch TFT in the vertical blank period and a second sensing gate pulse for turning on the second switch TFT in the vertical blank period.

4. The organic light emitting display of claim 3 , wherein the image display period includes:
an image display initialization period, in which a source voltage of the driving TFT is initialized to a previously determined reference voltage in response to the first image display gate pulse of an off-level and the second image display gate pulse of an on-level;
an image display programming period, in which the image display data voltage is applied to the gate electrode of the driving TFT in response to the first and second image display gate pulses of the on-level in the initialization state of the source voltage of the driving TFT and turns on the driving TFT; and
an image display emission period, in which the organic light emitting diode operates using an image display driving current applied through the driving TFT in response to the first and second image display gate pulses of the off-level and displays an original image.

5. The organic light emitting display of claim 3 , wherein the vertical blank period includes:
a sensing initialization period, in which a source voltage of the driving TFT is firstly initialized to a first reference voltage, which is previously determined, in response to the first sensing gate pulse of an off-level and the second sensing gate pulse of an on-level;
a sensing programming period, in which a sensing data voltage is applied to the gate electrode of the driving TFT in response to the first and second sensing gate pulses of the on-level in the first initialization state of the source voltage of the driving TFT and sets the driving TFT to a turn-on state;
a sensing period, in which the source voltage of the driving TFT increased by a current flowing in the driving TFT is sensed and stored in response to the first sensing gate pulse of the off-level and the second sensing gate pulse of the on-level;
a sampling period, in which the sensed source voltage of the driving TFT is sampled and detected as the changes in the electrical characteristic of the driving TFT in response to the first and second sensing gate pulses of the on-level;
a luminance recovery initialization period, in which the source voltage of the driving TFT is secondly initialized to a second reference voltage in response to the first sensing gate pulse of the off-level and the second sensing gate pulse of the on-level;
a luminance recovery programming period, in which the luminance recovery data voltage is applied to the gate electrode of the driving TFT in response to the first and second sensing gate pulses of the on-level in the second initialization state of the source voltage of the driving TFT and turns on the driving TFT; and
a luminance recovery emission period, in which the organic light emitting diode operates using a luminance recovery driving current applied through the driving TFT in response to the first and second sensing gate pulses of the off-level and displays a luminance recovery image.

6. The organic light emitting display of claim 5 , wherein during the luminance recovery initialization period, the first sensing gate pulse is maintained at the off-level, and the second sensing gate pulse is maintained at the off-level and then is changed to the on-level.

7. The organic light emitting display of claim 5 , wherein the first reference voltage is less than the second reference voltage.

8. The organic light emitting display of claim 5 , wherein a black display data voltage capable of turning off the driving TFT is applied to the gate electrode of the driving TFT during the sampling period.

9. The organic light emitting display of claim 1 , wherein the luminance recovery data voltage has the same voltage level as the image display data voltage applied to the sensing target display line during the image display period.

10. The organic light emitting display of claim 9 , further comprising a timing controller configured to control an operation of the gate driving circuit and an operation of the data driving circuit, modulate image display digital data to be applied to the display lines during the image display period to compensate for the changes in the electrical characteristic of the driving TFT, and modulate luminance recovery digital data to be applied to the sensing target display line during the vertical blank period to compensate for a luminance deviation between the sensing target display line and another display line,
wherein the image display digital data corresponds to the image display data voltage, and the luminance recovery digital data corresponds to the luminance recovery data voltage.

11. The organic light emitting display of claim 10 , wherein a compensation value for modulating the luminance recovery digital data varies depending on a location of the sensing target display line.

12. The organic light emitting display

Assignees

• Lg Display Co Ltd
• Lg Display Co Ltd

Inventors

• Tani Ryosuke
• Hong Sungjin
• Nam Woojin
• Park Joonmin
• Lee Seonmi
• Yang Inyoung
• Lee Jongho

Classifications

• G09G2320/045

  Compensation of drifts in the characteristics of light emitting or modulating elements · CPC title

• G09G3/3291

  in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements · CPC title

• G09G2320/043

  Preventing or counteracting the effects of ageing · CPC title

• G09G2310/0254

  Control of polarity reversal in general, other than for liquid crystal displays · CPC title

• G09G3/3233 Primary

  with pixel circuitry controlling the current through the light-emitting element · CPC title