Organic light emitting display for sensing degradation of organic light emitting diode

Patent metadata

Field	Value
Publication number	US-2016012798-A1
Application number	US-201414584214-A
Country	US
Kind code	A1
Filing date	Dec 29, 2014
Priority date	Jul 10, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

An organic light emitting display includes a display panel including a plurality of pixels, each of the plurality of pixels including an organic light emitting diode (OLED) and a driving thin film transistor (TFT) to control an emission amount of the OLED, the plurality of pixels connected to respective sensing lines; and at least one sensing unit connected to a corresponding one of the pixels through the respective sensing line, the at least one sensing unit configured to sense an amount of carriers accumulated in a parasitic capacitor of the OLED of the corresponding one of the pixels when a driving current flows in the OLED, the at least one sensing unit thereby sensing a degradation of the OLED.

First claim

What is claimed is:

1 . An organic light emitting display, comprising:
a display panel including a plurality of pixels,
each of the plurality of pixels including an organic light emitting diode (OLED) and a driving thin film transistor (TFT) to control an emission amount of the OLED,
the plurality of pixels connected to respective sensing lines; and
at least one sensing unit connected to a corresponding one of the pixels through the respective sensing line, wherein the at least one sensing unit is configured to sense an amount of carriers accumulated in a parasitic capacitor of the OLED of the corresponding one of the pixels when a driving current flows in the OLED, the at least one sensing unit thereby sensing a degradation of the OLED.

2 . The organic light emitting display of claim 1 , wherein the at least one sensing unit includes one of a current integrator and a current comparator.

3 . The organic light emitting display of claim 1 , wherein the display is configured to include a sensing process for sensing the amount of carriers of the parasitic capacitor, the sensing process including a data writing period, a boosting period, and a sensing period,
wherein in the data writing period, a gate-to-source voltage of the driving TFT is set to provide the driving current flowing in the OLED, wherein in the boosting period, an anode voltage of the OLED is boosted by the driving current flowing through the OLED and is stored in the parasitic capacitor of the OLED, wherein in the sensing period, the driving TFT is set to turn off the driving current flowing through the OLED, and the amount of carriers accumulated in the parasitic capacitor of the OLED is sensed by the sensing unit.

4 . The organic light emitting display of claim 3 , wherein the sensing process further includes a discharge period positioned in time between the boosting period and the sensing period,
wherein in the discharge period, the amount of carriers accumulated in the parasitic capacitor of the OLED is discharged to a threshold voltage of the OLED.

5 . The organic light emitting display of claim 1 , wherein each pixel includes:
a first switch TFT connected between a data line and a gate electrode of the driving TFT and configured to turn on in response to a scan control signal; a second switch TFT connected between the sensing line and a source electrode of the driving TFT and configured to turn on in response to a sensing control signal; and a storage capacitor connected between the gate electrode and the source electrode of the driving TFT.

6 . The organic light emitting display of claim 5 , wherein the scan control signal and the sensing control signal are the same.

7 . The organic light emitting display of claim 1 , wherein the sensing lines are independently connected to horizontally adjacent pixels, respectively.

8 . The organic light emitting display of claim 1 , wherein the sensing lines are commonly connected to at least two horizontally adjacent pixels.

9 . A method of forming an organic light emitting display, comprising:
forming a display panel including a plurality of pixels,
each of the plurality of pixels including an organic light emitting diode (OLED) and a driving thin film transistor (TFT) to control an emission amount of the OLED,
the plurality of pixels connected to respective sensing lines; and
forming at least one sensing unit connected to a corresponding one of the pixels through the respective sensing line, wherein the at least one sensing unit is configured to sense an amount of carriers accumulated in a parasitic capacitor of the OLED of the corresponding one of the pixels when a driving current flows in the OLED the at least one sensing unit thereby sensing a degradation of the OLED.

10 . The method of claim 9 , wherein forming the at least one sensing unit includes forming one of a current integrator and a current comparator.

11 . The method of claim 9 , wherein the display is configured to include a sensing process for sensing the amount of carriers of the parasitic capacitor, the sensing process including a data writing period, a boosting period, and a sensing period,
wherein in the data writing period, a gate-to-source voltage of the driving TFT is set for the driving current, wherein in the boosting period, an anode voltage of the OLED is boosted by the driving current flowing through the OLED and is stored in the parasitic capacitor of the OLED, wherein in the sensing period, the driving TFT is set to turn off the driving current flowing through the OLED, and the amount of carriers accumulated in the parasitic capacitor of the OLED is sensed by the sensing unit.

12 . The method of claim 11 , wherein the sensing process further includes a discharge period positioned in time between the boosting period and the sensing period,
wherein in the discharge period, the amount of carriers accumulated in the parasitic capacitor of the OLED is discharged to a threshold voltage of the OLED.

13 . The method of claim 9 , wherein each pixel includes:
a first switch TFT connected between a data line and a gate electrode of the driving TFT and configured to turn on in response to a scan control signal; a second switch TFT connected between the sensing line and a source electrode of the driving TFT and configured to turn on in response to a sensing control signal; and a storage capacitor connected between the gate electrode and the source electrode of the driving TFT.

14 . The method of claim 13 , wherein the scan control signal and the sensing control signal are the same.

15 . The method of claim 9 , wherein the sensing lines are independently connected to horizontally adjacent pixels, respectively.

16 . The method of claim 9 , wherein the sensing lines are commonly connected to at least two horizontally adjacent pixels.

Assignees

• Lg Display Co Ltd

Inventors

• Oh Hyemi
• Shin Hunki
• Kim Changhee

Classifications

• G09G2320/045

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

• G09G2320/029

  by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel · CPC title

• G09G2310/027

  Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters · CPC title

• G09G2300/0847

  being a dynamic memory without any storage capacitor, i.e. with use of parasitic capacitances as storage elements · CPC title

• G09G2300/0465

  Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness · CPC title