AMOLED external electrical compensation detection method

Patent metadata

Field	Value
Publication number	US-10490124-B2
Application number	US-201715579538-A
Country	US
Kind code	B2
Filing date	Nov 25, 2017
Priority date	Oct 18, 2017
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

The present disclosure provides an AMOLED external electrical compensation detection method, in the display mode, estimating a cross-voltage between the drain and the source of the detecting TFT, calculating a gate-source voltage of the driving TFT based on the estimated value, it is possible to improve the writing precision of the gate-source voltage of the driving TFT; in the detection mode, estimating a cross-voltage between the drain and the source of the detecting TFT, calculating a source voltage of the driving TFT based on the estimated value, calculating the threshold voltage and the carrier mobility of the driving TFT based on the calculated voltage of the source of the driving TFT, it is possible to reduce the calculation error between the threshold voltage and the carrier mobility of the driving TFT and improve the accuracy of the external electrical compensation detection of the AMOLED.

First claim

What is claimed is:

1. An AMOLED external electrical compensation detection method, comprising the steps of:
step S 1 : providing an AMOLED display;
the AMOLED display has an external compensation pixel circuit arranged in an array, the external compensation pixel circuit comprises a driving TFT, a switching TFT, a detecting TFT, an OLED and a capacitor;
a gate of the switching TFT is connected to receive a scanning signal, a drain of the switching TFT is connected to receive a data signal, a source of the switching TFT is electrically connected to a gate of the driving TFT; a drain of the driving TFT is connected to receive a positive voltage of a power supply, a source of the driving TFT is electrically connected to a drain of the detecting TFT; a gate of the detecting TFT is connected to receive a control signal, a source of the detecting TFT is electrically connected to a detecting wire; an anode of the OLED is electrically connected to the source of the driving TFT, a cathode of the OLED is connected to receive a negative voltage of the power supply; a terminal of the capacitor is electrically connected to the gate of the driving TFT, and another terminal of the capacitor is electrically connected to the source of the driving TFT;
step S 2 : entering a display mode, estimating an estimated value of a cross-voltage between the drain and the source of the detecting TFT in the display mode, and calculating a gate-source voltage of the driving TFT based on the estimated value of the cross-voltage between the drain and the source of the detecting TFT in the display mode; and
step S 3 : entering a detection mode, estimating an estimated value of a cross-voltage between the drain and the source of the detecting TFT in the detection mode, and calculating a source voltage of the driving TFT based on the estimated value of the cross-voltage between the drain and the source of the detecting TFT in the detection mode,
wherein in the step S 2 , an estimation formula of the cross-voltage between the drain and the source of the detecting TFT in the display mode is:

V

ds
⁢

⁢
3

=

2
⁢
a

+
b
-

b
2

+

4
⁢
ab

2

;

V ds3 is the cross-voltage between the drain and the source of the detecting TFT;
a=V Data −V cm V th1 ;

V Data is a voltage of the data signal, V cm is the constant voltage, and V th1 is a design value of the threshold voltage of the driving TFT;

b
=

2
⁢

L
1

⁢

W
3

W
1

⁢

L
3

⁢

(

VGH
-

V
cm

-

V

th
⁢

⁢
3

)

;

wherein, L 1 is a channel length of the driving TFT, W 1 is a channel width of the driving TFT, L 3 is a channel length of the detecting TFT, W 3 is a channel width of the detecting TFT, VGH is a voltage of the gate of the driving TFT at the moment of opening, and V th3 is a design value of the threshold voltage of the detecting TFT.

2. The AMOLED external electrical compensation detection method according to claim 1 , further comprising a step S 4 , calculating a threshold voltage and a carrier mobility of the driving TFT based on the voltage of the source of the driving TFT calculated in the step S 3 .

3. The AMOLED external electrical compensation detection method according to claim 1 , in the step S 2 , the scanning signal controls the switching TFT to turn on, the control signal controls the detecting TFT to turn on, the detecting wire connects to receive a constant voltage, a voltage of the data signal is written into the gate of the driving TFT, and the detecting TFT operates in its linear area.

4. The AMOLED external electrical compensation detection method according to claim 1 , in the step S 2 , a calculation formula of the gate-source voltage of the driving TFT is:
V gs =V Data −V cm −V ds3 ;
wherein, V gs is the gate-source voltage of the driving TFT.

5. The AMOLED external electrical compensation detection method according to claim 1 , in the step S 3 , the detection mode is divided into a potential resetting stage and a charging stage; in the potential resetting stage, the scanning signal controls the switching TFT to turn on, the control signal controls the detecting TFT to turn on, the detecting wire connects to receive a constant voltage, and a voltage of the data signal is written into the gate of the driving TFT; in the charging stage, the scanning signal controls the switching TFT to turn off, the control signal still controls the detecting TFT to turn on, and the detecting wire is floating and the voltage of the source of the detecting TFT is detected.

6. The AMOLED external electrical compensation detection method according to claim 5 , in the charging stage of the step S 3 , an estimation formula of the cross-voltage between the drain and the source of the detecting TFT in the detection mode is:

V

ds
⁢

⁢
3

=

2
⁢
a

+
y

Assignees

• Shenzhen China Star Optoelectronics Semiconductor Display Tech Co Ltd

Inventors

• Xie Hongjun

Classifications

• G09G2320/029

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

• G09G2320/043

  Preventing or counteracting the effects of ageing · CPC title

• G09G2300/0819

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

• G09G3/006 Primary

  Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays (testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309) · CPC title

• G09G2330/12

  Test circuits or failure detection circuits included in a display system, as permanent part thereof · CPC title