# US 10,311,794 B2 · Pixel driver circuit and driving method thereof

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- Number: US 10,311,794 B2
- Document ID: US10311794B2
- Status: Granted
- Kind: B2
- Application number: 15/580,273
- Filed: 2017-11-16
- Published: 2019-02-28
- Granted: 2019-06-04
- Earliest claimed: 2017-08-23
- Assignees: Shenzhen China Star Optoelectronics Semiconductor Display Technology Co., Ltd.
- Applicants: Shenzhen China Star Optoelectronics Semiconductor Display Technology Co., Ltd.
- Inventors: Xuebing Zhou; Xiaolong Chen
- Web page: https://patentgrep.com/patent/US10311794B2

## CPC

- G09G 3/3233: with pixel circuitry controlling the current through the light-emitting element
- G09G 3/3258: with pixel circuitry controlling the voltage across the light-emitting element
- G09G 3/3266: Details of drivers for scan electrodes
- H10D 86/40: characterised by multiple TFTs
- H10D 86/60: wherein the TFTs are in active matrices
- G09G 2300/0819: used for counteracting undesired variations, e.g. feedback or autozeroing
- G09G 2300/0852: being a dynamic memory with more than one capacitor
- G09G 2310/0251: Precharge or discharge of pixel before applying new pixel voltage
- G09G 2310/0262: 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
- G09G 2310/0264: Details of driving circuits
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- G09G 2320/043: Preventing or counteracting the effects of ageing
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

The invention discloses a pixel driver circuit and driving method thereof. The pixel driver circuit comprises a first TFT (T1) connected to first node (G) and second node (K); a second TFT (T2), connected to first control signal (S1), first node (G) and second node (K); a third TFT (T3), connected to second control signal (S2) and second node (K); a fourth TFT (T4), connected to first control signal (S1), third node (N) and reference voltage (Vref); a fifth TFT (T5), connected to first control signal (S1), third node (N) and data signal (Vdata); a sixth TFT (T6), connected to third control signal (S3); a first capacitor (C1) and a second capacitor; the reference voltage (Vref) being less than data signal Vdata). The invention also provides a corresponding driving method. The invention uses internal detection to eliminate luminance inconsistency caused by change of the driving TFT threshold voltage.

## Claims

### Claim 1

A pixel driver circuit, which comprises:
a first thin film transistor (TFT), having a gate connected to a first node, a source and a drain connected respectively to a high voltage power source and a second node;
a second TFT, having a gate connected to a first control signal, a source and a drain connected respectively to the first node and the second node;
a third TFT, having a gate connected to a second control signal, a source and a drain connected respectively to the second node and an anode of an organic light-emitting diode (OLED),
the OLED, having a cathode connected to a low voltage power source;
a fourth TFT, having a gate connected to the first control signal, a source and a drain connected respectively to a third node and a reference voltage;
a fifth TFT, having a gate connected to the first control signal, a source and a drain connected respectively to the third node and a data signal;
a sixth TFT, having a gate connected to a third control signal, a source and a drain connected respectively to the third node and the first node;
a first capacitor, having two ends connected respectively to the first node and the high voltage power source; and
a second capacitor, having two ends connected respectively to the first node and the third node;
wherein the reference voltage having a voltage level less than the data signal;
wherein the first control signal, the second control signal, and the third control signal are configured for an initialization phase, a threshold voltage detection phase, and a light-emitting phase; and
wherein in the initialization phase, the first control signal keeps at high voltage, the second control signal keeps at high voltage, and the third control signal keeps at low voltage.

### Claim 2 (depends on 1)

The pixel driver circuit as claimed in claim 1, wherein the first TFT, the second TFT, the third TFT, the fifth TFT, and the sixth TFT are P-type TFTs, and the fourth TFT is an N-type TFT.

### Claim 3 (depends on 1)

The pixel driver circuit as claimed in claim 1, wherein in the threshold voltage detection phase, the first control signal keeps at low voltage, the second control signal keeps at high voltage, and the third control signal keeps at high voltage.

### Claim 4 (depends on 1)

The pixel driver circuit as claimed in claim 1, wherein in the light-emitting phase, the first control signal keeps at high voltage, the second control signal keeps at low voltage, and the third control signal keeps at high voltage.

### Claim 5 (depends on 1)

A driving method of the pixel driver circuit as claimed in claim 1, wherein in the threshold voltage detection phase, the first control signal keeps at low voltage, the second control signal keeps at high voltage, and the third control signal keeps at high voltage.

### Claim 6 (depends on 1)

The driving method of the pixel driver circuit as claimed in claim 1, wherein in the light-emitting phase, the first control signal keeps at high voltage, the second control signal keeps at low voltage, and the third control signal keeps at high voltage.

### Claim 7

A pixel driver circuit, which comprises:
a first thin film transistor (TFT), having a gate connected to a first node, a source and a drain connected respectively to a high voltage power source and a second node;
a second TFT, having a gate connected to a first control signal, a source and a drain connected respectively to the first node and the second node;
a third TFT, having a gate connected to a second control signal, a source and a drain connected respectively to the second node and an anode of an organic light-emitting diode (OLED),
the OLED, having a cathode connected to a low voltage power source;
a fourth TFT, having a gate connected to the first control signal, a source and a drain connected respectively to a third node and a reference voltage;
a fifth TFT, having a gate connected to the first control signal, a source and a drain connected respectively to the third node and a data signal;
a sixth TFT, having a gate connected to a third control signal, a source and a drain connected respectively to the third node and the first node;
a first capacitor, having two ends connected respectively to the first node and the high voltage power source; and
a second capacitor, having two ends connected respectively to the first node and the third node;
wherein the reference voltage having a voltage level less than the data signal;
wherein the first TFT, the second TFT, the third TFT, the fifth TFT, and the sixth TFT being P-type TFTs, and the fourth TFT being an N-type TFT;
wherein the first control signal, the second control signal, and the third control signal being configured for an initialization phase, a threshold voltage detection phase, and a light-emitting phase;
wherein in the initialization phase, the first control signal keeping at high voltage, the second control signal keeping at high voltage, and the third control signal keeping at low voltage;
wherein in the threshold voltage detection phase, the first control signal keeping at low voltage, the second control signal keeping at high voltage, and the third control signal keeping at high voltage.

### Claim 8 (depends on 7)

The pixel driver circuit as claimed in claim 7, wherein in the light-emitting phase, the first control signal keeps at high voltage, the second control signal keeps at low voltage, and the third control signal keeps at high voltage.