Pixel circuit, organic light emitting display device and driving method for the same

Patent metadata

Field	Value
Publication number	US-2020184886-A1
Application number	US-201916703753-A
Country	US
Kind code	A1
Filing date	Dec 4, 2019
Priority date	Dec 6, 2018
Publication date	Jun 11, 2020
Grant date	—

Abstract

The present disclosure relates to a pixel circuit and an organic light emitting display device that include an organic light emitting diode, a first transistor receiving a pixel power source in response to a data signal and supplying a driving current to the organic light emitting diode, and a capacitor holding the data signal supplied to the first transistor, and to a method of driving the pixel circuit and the organic light emitting display device. In the capacitor, after a first voltage corresponding to a threshold voltage of the first transistor is stored, a second voltage resulting from compensating the first voltage relative to mobility of the first transistor is stored, and a value obtained by adding a third voltage corresponding to the data signal to the second voltage in response to the data signal is stored.

First claim

What is claimed is:

1 . An organic light emitting display device comprising:
a display panel in which a plurality of pixels is arranged; a data driver transferring a data signal to at least one pixel of the plurality of pixels; a gate driver transferring a gate signal to the at least one pixel; and a timing controller controlling the data driver and the gate driver, wherein the at least one pixel comprises:
an organic light emitting diode;
a first transistor receiving a pixel power source when the data signal is transferred and supplying a driving current to the organic light emitting diode, wherein the first transistor supplies the driving current to the organic light emitting diode based on a threshold voltage and an electron mobility of the first transistor; and
a capacitor connected to the first transistor and the organic light emitting diode,
wherein the capacitor holds the data signal supplied to the first transistor,
wherein after a first voltage corresponding to the threshold voltage of the first transistor has been stored in the capacitor, a second voltage resulted from compensating the first voltage for the electron mobility of the first transistor is stored in the capacitor, and when the data signal is transferred, a value obtained by adding a third voltage corresponding to the data signal to the second voltage is stored in the capacitor.

2 . The organic light emitting display device according to claim 1 ,
wherein the at least one pixel further comprises: a second transistor supplying the data signal to the first transistor; a third transistor supplying the pixel power source to the first transistor; a fourth transistor transferring an initialization voltage for initializing the capacitor; and a fifth transistor enabling the first voltage to be stored at the capacitor by supplying a first reference voltage to the first transistor, and enabling the second voltage to be stored at the capacitor by supplying a second reference voltage to the first transistor.

3 . The organic light emitting display device according to claim 1 ,
wherein a gate electrode, a first electrode and a second electrode of the first transistor are connected to a first node, a second node and a third node, respectively, and an anode electrode and a cathode electrode of the capacitor are connected to the third node and a second power source, respectively, wherein the at least one pixel further comprises:
a second transistor having a gate electrode connected to a gate line, a first electrode connected to a data line, and a second electrode connected to the first node;
a third transistor having a gate electrode connected to a sensing control signal line, a first electrode connected to an initialization voltage line, and a second electrode connected to the third node;
a fourth transistor having a gate electrode connected to a light emitting control signal line, a first electrode connected to the pixel power source, and a second electrode connected to the second node; and
a fifth transistor having a gate electrode connected to a sampling control signal line, a first electrode connected to a reference voltage line, and a second electrode connected to the first node.

4 . The organic light emitting display device according to claim 3 , wherein the gate driver outputs the gate signal transferred to the gate line, a light emitting control signal transferred to the light emitting control signal line, a sensing control signal transferred to the sensing control signal line, and a sampling signal transferred to the sampling control signal line.

5 . The organic light emitting display device according to claim 4 , wherein the sampling signal with a high level and the sensing control signal with a high level are supplied in a first interval, the sampling signal with the high level and the light emitting control signal with a high level are supplied in a second interval, the sampling signal with the high level and the light emitting control signal with the high level are supplied in a third interval, the gate signal with a high level is supplied in a fourth interval, and the light emitting control signal with the high level are supplied in a fifth interval.

6 . The organic light emitting display device according to claim 5 , wherein a first reference voltage is transferred to the reference voltage line in the second interval, and a second reference voltage with a higher level than the first reference voltage is transferred to the reference voltage line in the third interval.

7 . The organic light emitting display device according to claim 4 , wherein the sensing control signal is transferred to the at least one pixel at an earlier time than a gate signal transferred to an n-th pixel row of the plurality of pixels.

8 . The organic light emitting display device according to claim 1 , wherein the first transistor comprises an oxide semiconductor.

9 . A pixel circuit comprising:
a first transistor having a gate electrode connected to a first node, a first electrode connected to a second node, and a second electrode connected to a third node; a second transistor having a gate electrode connected to a gate line, a first electrode connected to a data line, and a second electrode connected to the first node; a third transistor having a gate electrode connected to a sensing control signal line, a first electrode connected to an initialization voltage line, and a second electrode connected to the third node; a fourth transistor having a gate electrode connected to a light emitting control signal line, a first electrode connected to a pixel power source, and a second electrode connected to the second node; a fifth transistor having a gate electrode connected to a sampling signal line, a first electrode connected to a reference voltage line, and a second electrode connected to, the first node; a capacitor connected between the first node and the third node; and an organic light emitting diode connected to the third node.

10 . The pixel circuit according to claim 9 , wherein a sampling signal with a high level and a sensing control signal with a high level are supplied to the sampling signal line and the sensing control signal line respectively in a first interval, the sampling signal with the high level and a light emitting control signal with a high level are supplied to the sampling signal line and the light emitting control signal line respectively in a second interval, the sampling signal with the high level and the light emitting control signal with the high level are supplied to the sampling signal line and the light emitting control signal line respectively in a third interval, a gate signal with a high level is supplied to the gate line in a fourth interval, and the light emitting control signal with the high level are supplied to the light emitting control signal line in a fifth interval.

11 . The pixel circuit according to claim 10 , wherein a first reference voltage is transferred to the reference voltage line in the second interval, and a second reference voltage with a higher level than the first reference voltage is transferred to the reference voltage line in the third interval.

12 . The pixel circuit according to claim 10 , wherein the sensing control signal is a gate signal transferred at an earlier time than a gate signal transferred to an n-th pixel row of a plurality of pixels.

13 . The pixel circuit according to claim 9 , wherein at least one of the first, second, third, fourth and fifth transistors comprises an oxide semiconductor.

14 . A method of driving an organic light emitting display device comprising an

Assignees

• Lg Display Co Ltd

Inventors

• Chun Kwangil

Classifications

• G09G2300/0852

  being a dynamic memory with more than one capacitor · CPC title

• G09G2330/021

  Power management, e.g. power saving · CPC title

• G09G3/3233 Primary

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

• G09G2300/0819

  used for counteracting undesired variations, e.g. feedback or autozeroing · CPC title

• G09G2300/0861

  with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes · CPC title