Pixel and organic light emitting display device having the same

Patent metadata

Field	Value
Publication number	US-9984623-B2
Application number	US-201615149757-A
Country	US
Kind code	B2
Filing date	May 9, 2016
Priority date	Sep 24, 2015
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

An organic light emitting display device includes a display panel including and a plurality of pixels, a gate driver configured to a normal gate signal and an alternative gate signal to the pixels, a data driver configured to provide a data signal to the pixels, an emission control driver configured to an emission control signal to the pixels, and a controller configured to control the gate driver, the data driver, and the emission control driver. Each of the pixels is driven by the normal gate signal in a first driving mode and is driven by the alternative gate signal in a second driving mode. A threshold voltage of a first transistor is compensated in the first driving mode and the threshold voltage of the first transistor is not compensated in the second driving mode.

First claim

What is claimed is:

1. An organic light emitting display device comprising:
a display panel including and a plurality of pixels;
a gate driver configured to provide a normal gate signal and an alternative gate signal to the pixels;
a data driver configured to provide a data signal to the pixels;
an emission control driver configured to provide an emission control signal to the pixels; and
a controller configured to control the gate driver, the data driver, and the emission control driver,
wherein each of the pixels is driven by the normal gate signal in a first driving mode in which a threshold voltage of a first transistor is compensated and is driven by the alternative gate signal in a second driving mode in which the threshold voltage of the first transistor is not compensated.

2. The display device of claim 1 , wherein each of the pixels includes:
an organic light emitting diode;
a first transistor including a first electrode connected to a first node, a second node connected to a second node, and a gate electrode connected to a third node;
a second transistor including a first electrode receiving the data signal, a second electrode connected to the first node, and a gate electrode receiving the normal gate signal;
a third transistor including a first electrode connected to the second node, a second electrode connected to the third node, and a gate electrode receiving the normal gate signal;
a fourth transistor including a first electrode connected to a first power source, a second electrode connected to the first node, and a gate electrode receiving the emission control signal;
a fifth transistor including a first electrode connected to the second node, a second electrode connected to a first electrode of the organic light emitting diode, and a gate electrode receiving the emission control signal;
a sixth transistor including a first electrode receiving the data signal, a second electrode connected to the third node, and a gate electrode receiving the alternative gate signal; and
a capacitor including a first electrode connected to the third node and a second electrode connected to the first power source.

3. The display device of claim 2 , wherein each of the pixels further includes:
a seventh transistor including a first electrode connected to an initialization power source, a second electrode connected to the third node, and a gate electrode receiving a first initialization gate signal.

4. The display device of claim 3 , wherein each of the pixels further includes:
an eighth transistor including a first electrode connected to the initialization power source, a second electrode connected to the first electrode of the organic light emitting diode, and a gate electrode receiving a second initialization gate signal.

5. The display device of claim 4 , wherein the first initialization gate signal is substantially the same as the second initialization gate signal, and
wherein the normal gate signal and the first initialization gate signal are applied to each of the pixels with an interval of one horizontal period.

6. The display device of claim 1 , wherein the controller includes:
an image data analyzer configured to derive at least one selected from a grayscale distribution of image data, a first difference value between image data of a current frame and image data of a previous frame, and a second difference value between image data of adjacent pixels;
a driving determiner configured to determine a panel driving mode and a driving frequency based on at least one selected from the grayscale distribution, the first difference value, and the second difference value; and
a control signal controller configured to generate a control signal for controlling the gate driver, the data driver, and the emission control driver based on the panel driving mode and the driving frequency.

7. The display device of claim 6 , wherein the driving determiner includes:
a driving mode selector configured to select the first driving mode or the second driving mode as the panel driving mode based on at least one selected from the grayscale distribution, the first difference value, and the second difference value; and
a driving frequency determiner configured to determine the driving frequency based on at least one selected from the grayscale distribution, the first difference value, and the second difference value.

8. The display device of claim 7 , wherein the driving mode selector derives a first number of pixels each of which grayscale is higher than or equal to a reference grayscale from the grayscale distribution, selects the first driving mode as the panel driving mode when the first number is lower than a first reference value, and selects the second driving mode as the panel driving mode when the first number is higher than or equal to the first reference value.

9. The display device of claim 7 , wherein the driving frequency determiner derives a first number of pixels each of which grayscale is higher than or equal to a reference grayscale from the grayscale distribution, set the driving frequency to a first frequency when the first number is lower than a first reference value, and set the driving frequency to a second frequency lower than the first frequency when the first number is higher than or equal to the first reference value.

10. The display device of claim 7 , wherein the driving mode selector selects the first driving mode as the panel driving mode when the first difference is higher than or equal to a second reference value and selects the second driving mode as the panel driving mode when the first difference is lower than the second reference value.

11. The display device of claim 7 , wherein the driving frequency determiner set the driving frequency to a first frequency when the first difference is higher than or equal to a second reference value and set the driving frequency to a second frequency lower than the first frequency when the first difference is lower than the second reference value.

12. The display device of claim 7 , wherein the driving mode selector selects the first driving mode as the panel driving mode when the second difference is lower than a third reference value and selects the second driving mode as the panel driving mode when the second difference is higher than or equal to the third reference value.

13. The display device of claim 7 , wherein the driving frequency determiner set the driving frequency to a first frequency when the second difference is lower than a third reference value and set the driving frequency to a second frequency lower than the first frequency when the second difference is higher than or equal to the third reference value.

14. The display device of claim 7 , wherein the driving determiner further includes:
an emission controller configured to adjust a length of an off-period of the emission control signal based on at least one selected from the grayscale distribution, the first difference value, and the second difference value.

15. The display device of claim 6 , wherein the control signal generator generates the control signal such that the normal gate signal is sequentially outputted to a plurality of normal gate lines when the panel driving mode is the first driving mode, and generates the control signal such that the alternative gate signal is sequentially outputted to a plurality of alternative gate lines when the panel driving mode is the second driving mode.

16. The display device of claim 6 , wherein the control signal generator generates the control signal such that the emission control signal is an off-level in at lea

Assignees

• Samsung Display Co Ltd

Inventors

• An Tae-Hyeong
• Jin Ja-Kyoung

Classifications

• G09G3/3275

  Details of drivers for data electrodes · CPC title

• G09G3/3233 Primary

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

• G09G2340/0435

  Change or adaptation of the frame rate of the video stream · CPC title

• G09G2300/0842

  forming a memory circuit, e.g. a dynamic memory with one capacitor · CPC title

• G09G2310/0262

  The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes · CPC title