# US 10,762,841 B2 · Pixel circuit, driving method thereof and display device

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- Number: US 10,762,841 B2
- Document ID: US10762841B2
- Status: Granted
- Kind: B2
- Application number: 16/439,034
- Filed: 2019-06-12
- Published: 2019-09-26
- Granted: 2020-09-01
- Earliest claimed: 2017-10-31
- Assignees: KunShan Go-Visionox Opto-Electronics Co., Ltd
- Applicants: KunShan Go-Visionox Opto-Electronics Co., Ltd.
- Inventors: Yanan Ji; Wenzhi Fan
- Web page: https://patentgrep.com/patent/US10762841B2

## CPC

- G09G 3/3233: with pixel circuitry controlling the current through the light-emitting element
- G09G 3/22: using controlled light sources
- G09G 3/3208: organic, e.g. using organic light-emitting diodes [OLED]
- G09G 3/3266: Details of drivers for scan electrodes
- G09G 3/3291: in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
- G09G 2300/0426: Layout of electrodes and connections
- G09G 2300/0439: Pixel structures
- G09G 2300/0809: Several active elements per pixel in active matrix panels
- G09G 2300/0861: with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
- 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 2320/0223: Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
- 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)

## Abstract

The disclosure discloses a pixel circuit and a driving method thereof, a display device. The pixel circuit includes a first through six thin film transistors, a light-emitting diode and a storage capacitor. A gate of the first thin film transistor is separately connected to a source of the second thin film transistor, a source of the third thin film transistor and one end of the storage capacitor. The other end of the storage capacitor is separately connected to a drain of the fourth thin film transistor and a source of the fifth thin film transistor. A source of the first thin film transistor is connected to a first power source. A drain of the first thin film transistor is separately connected to a drain of the second thin film transistor and a source of the sixth thin film transistor.

## Claims

### Claim 1

A pixel circuit, comprising:
a first thin film transistor, a second thin film transistor, a third thin film transistor, a fourth thin film transistor, a fifth thin film transistor, a sixth thin film transistor, a light-emitting diode and a storage capacitor,
wherein, a gate of the first thin film transistor is separately connected to a source of the second thin film transistor, a source of the third thin film transistor and one end of the storage capacitor, a drain of the third thin film transistor is separately connected to a drain of the fifth thin film transistor and a reference voltage signal line, the other end of the storage capacitor is separately connected to a drain of the fourth thin film transistor and a source of the fifth thin film transistor, and a source of the fourth thin film transistor is connected to a data signal line;
a source of the first thin film transistor is connected to a first power source; and
a drain of the first thin film transistor is separately connected to a drain of the second thin film transistor and a source of the sixth thin film transistor, a drain of the sixth thin film transistor is connected to an anode of the light-emitting diode, and a cathode of the light-emitting diode is connected to a second power source,
wherein the reference voltage signal line provides a reference voltage, and the reference voltage is a negative voltage and initializes the gate of the first thin film transistor and one end of the storage capacitor, and the data signal line provides a data voltage,
wherein a gate of the third thin film transistor is connected to a first scan line, the first scan line provides a first scan signal and the first scan signal controls the third thin film transistor to make the third thin film transistor set in an on-state or an off-state,
a gate of the fourth thin film transistor is connected to a second scan line, the second scan line provides a second scan signal, and the second scan signal controls the fourth thin film transistor to make the fourth thin film transistor set in the on-state or the off-state,
a gate of the second thin film transistor and a gate of the fifth thin film transistor are connected to a third scan line, the third scan line provides a third scan signal, and the third scan signal controls the second thin film transistor and the fifth thin film transistor to make the second thin film transistor and the fifth thin film transistor set in the on-state or the off-state, and
a gate of the sixth thin film transistor is connected to a first light-emitting control line, the first light-emitting control line provides a first light-emitting control signal, and the first light-emitting control signal controls the sixth thin film transistor to make the sixth thin film transistor set in the on-state or the off-state.

### Claim 2 (depends on 1)

The pixel circuit according to claim 1, wherein the first power source provides a power supply voltage for the first thin film transistor; and
a current flows into the second power source when the light-emitting diode emits light.

### Claim 3 (depends on 1)

The pixel circuit according to claim 1, wherein when the first scan signal controls the third thin film transistor to make the third thin film transistor set in the on-state, the reference voltage signal line is connected to the gate of the first thin film transistor and one end of the storage capacitor, and the reference voltage initializes the gate of the first thin film transistor and the one end of the storage capacitor;
when the second scan signal controls the fourth thin film transistor to make the fourth thin film transistor set in the on-state, the data signal line is connected to the other end of the storage capacitor, and the data voltage is input into the pixel circuit via the storage capacitor;
when the third scan signal controls the second thin film transistor and the fifth thin film transistor to make the second thin film transistor and the fifth thin film transistor set in the on-state, the gate of the first thin film transistor is connected to the drain of the first thin film transistor, a threshold voltage of the first thin film transistor is compensated, the reference voltage signal line is connected to the other end of the storage capacitor and initializes the other end of the storage capacitor; and
when the first light-emitting control signal controls the sixth thin film transistor to make the sixth thin film transistor set in the on-state, a current flows through the light-emitting diode, and the current is independent of the first power source.

### Claim 4 (depends on 1)

The pixel circuit according to claim 1, wherein the pixel circuit further comprises a seventh thin film transistor,
a source of the seventh thin film transistor is connected to the first power source, a drain of the seventh thin film transistor is connected to the source of the first thin film transistor, and a gate of the seventh thin film transistor is connected to a second light-emitting control line; and
the second light-emitting control line provides a second light-emitting control signal, and when the second light-emitting control signal controls the seventh thin film transistor to make the seventh thin film transistor in the on-state, the first power source is connected to the source of the first thin film transistor, and the first power source applies a voltage to the source of the first thin film transistor.

### Claim 5 (depends on 4)

The pixel circuit according to claim 4, wherein the seventh thin film transistor is a N-type thin film transistor or a P-type thin film transistor.

### Claim 6 (depends on 1)

The pixel circuit according to claim 1, wherein the pixel circuit further comprises an eighth thin film transistor,
a source of the eighth thin film transistor is connected to the reference voltage signal line, a drain of the eighth thin film transistor is connected to the anode of the light-emitting diode, a gate of the eighth thin film transistor is connected to a fourth scan line, and when a fourth scan signal controls the eighth thin film transistor to make the eighth thin film transistor in the on-state, the reference voltage initializes the anode of the light-emitting diode.

### Claim 7 (depends on 6)

The pixel circuit according to claim 6, wherein the eighth thin film transistor is a N-type thin film transistor or a P-type thin film transistor.

### Claim 8 (depends on 1)

The pixel circuit according to claim 1, wherein the first thin film transistor is a drive thin film transistor, and the first thin film transistor is a P-type thin film transistor; and
the second thin film transistor, the third thin film transistor, the fourth thin film transistor, the fifth thin film transistor, and the sixth thin film transistor are independently N-type thin film transistors or P-type thin film transistors.

### Claim 9 (depends on 1)

A driving method for the pixel circuit according to claim 1, comprising:
in a first stage, controlling the third thin film transistor to change the third thin film transistor from the off-state to the on-state by the first scan signal, and initializing the gate of the first thin film transistor and one end of the storage capacitor by the reference voltage, controlling the fourth thin film transistor to make the fourth thin film transistor set in the off-state by the second scan signal, controlling the second thin film transistor and the fifth thin film transistor to make the second thin film transistor and the fifth thin film transistor set in off-state by the third scan signal, and controlling the sixth thin film transistor to change the sixth thin film transistor from the on-state to the off-state by the first light-emitting control signal;
in a second stage, controlling the third thin film transistor to change the third thin film transistor from the on-state to the off-state by the first scan signal, controlling the fourth thin film transistor to make the fourth thin film transistor set in the off-state by the second scan signal, and controlling the second thin film transistor and the fifth thin film transistor to change the second thin film transistor and the fifth thin film transistor from the off-state to the on-state to compensate for the threshold voltage of the first thin film transistor by the third scan signal, and controlling the sixth thin film transistor to make the sixth thin film transistor set in the off-state by the first light-emitting control signal;
in a third stage, controlling the third thin film transistor to make the third thin film transistor set in the off-state by the first scan signal, and controlling the fourth thin film transistor to change the fourth thin film transistor from the off-state to the on-state by the second scan signal, applying a voltage to the other end of the storage capacitor by a data voltage, controlling the second thin film transistor and the fifth thin film transistor to change the second thin film transistor and the fifth thin film transistor from the on-state to the off-state by the third scan signal, and controlling the sixth thin film transistor to make the sixth thin film transistor set in the off-state by the first light-emitting control signal; and
in a fourth stage, controlling the third thin film transistor to make the third thin film transistor set in the off-state by the first scan signal, controlling the fourth thin film transistor to change the fourth thin film transistor from the on-state to the off-state by the second scan signal, controlling the second thin film transistor and the fifth thin film transistor to make the second thin film transistor and the fifth thin film transistor set in the off-state by the third scan signal, controlling the sixth thin film transistor to change the sixth thin film transistor from the off-state to the on-state by the first light-emitting control signal, and emitting light by the light-emitting diode.

### Claim 10 (depends on 9)

The driving method according to claim 9, wherein in the first stage, the voltage of the one end of the storage capacitor and the voltage of the gate of the first thin film transistor are both Vref, and Vref is the reference voltage.

### Claim 11 (depends on 10)

The driving method according to claim 10, wherein in the third stage, the voltage of the other end of the storage capacitor changes from Vref to Vdata, and the voltage of the gate of the first thin film transistor is VDD−Vth+Vdata−Vref under the action of the storage capacitor, in the fourth stage, the current flowing through the light-emitting diode is independent of the first power source, wherein Vdata is the data voltage.

### Claim 12 (depends on 9)

The driving method according to claim 9, wherein in the second stage, the gate of the first thin film transistor is connected to the drain of the first thin film transistor, and the first power source applies a voltage to the source of the first thin film transistor to make the voltage of gate of the first thin film transistor be VDD−Vth, and the threshold voltage of the first thin film transistor is compensated, wherein Vth is the threshold voltage of the first thin film transistor, and VDD is the first power supply.

### Claim 13 (depends on 9)

The driving method according to claim 9, wherein when the pixel circuit comprises the seventh thin film transistor, and the source of the seventh thin film transistor is connected to the first power source, the drain of the seventh thin film transistor is connected to the source of the first thin film transistor and a gate of the seventh thin film transistor is connected to the second light-emitting control line, the driving method further comprises:
in the first stage, the second light-emitting control signal provided by the second light-emitting control line controls the seventh thin film transistor to change the seventh thin film transistor from the on-state to the off-state;
in the second stage, the second light-emitting control signal controls the seventh thin film transistor to change the seventh thin film transistor from the off-state to the on-state;
in the third stage, the second light-emitting control signal controls the seventh thin film transistor to change the seventh thin film transistor from the on-state to the off-state; and
in the fourth stage, the second light-emitting control signal controls the seventh thin film transistor to change the seventh thin film transistor from the off-state to the on-state.

### Claim 14 (depends on 9)

The driving method according to claim 9, wherein when the pixel circuit comprises the eighth thin film transistor, the source of the eighth thin film transistor is connected to the reference voltage signal line, the drain of the eighth thin film transistor is connected to the anode of the light-emitting diode and the gate of the eighth thin film transistor is connected to the fourth scan line, the driving method further comprises:
in the first stage, the fourth scan signal provided by the fourth scan line controls the eighth thin film transistor to change the eighth thin film transistor from the off-state to the on-state;
in the second stage, the fourth scan signal controls the eighth thin film transistor to change the eighth thin film transistor from the on-state to the off-state;
in the third stage, the fourth scan signal controls the eighth thin film transistor to make the eighth thin film transistor set in the off-state; and
in the fourth stage, the fourth scan signal controls the eighth thin film transistor to make the eighth thin film transistor set in the off-state.

### Claim 15 (depends on 1)

A display device, comprising the pixel circuit according to claim 1.