# US 12,223,901 B2 · Pixel and display device including the same

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- Number: US 12,223,901 B2
- Document ID: US12223901B2
- Status: Granted
- Kind: B2
- Application number: 18/301,726
- Filed: 2023-04-17
- Published: 2023-10-19
- Granted: 2025-02-11
- Earliest claimed: 2022-04-18
- Assignees: Samsung Display Co., Ltd.
- Applicants: Samsung Display Co., Ltd.
- Inventors: Dae Youn Cho; Jong Woo Park; Jun Seok Oh; Yoon Suk Choi; Young Tae Choi
- Web page: https://patentgrep.com/patent/US12223901B2

## 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 2300/0819: used for counteracting undesired variations, e.g. feedback or autozeroing
- G09G 2300/0842: forming a memory circuit, e.g. a dynamic memory with one capacitor
- 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 2310/0202: Addressing of scan or signal lines
- 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 2310/08: Details of timing specific for flat panels, other than clock recovery
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- G09G 2320/0247: Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
- G09G 2340/0435: Change or adaptation of the frame rate of the video stream
- 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

A pixel of a display device may pre-charge a light emitting element in non-emission periods immediately before emission periods by varying a voltage level of an initialization voltage. As a result, a luminance non-uniformity phenomenon that may occur as the result of a deterioration deviation of the light emitting element may be removed or reduced.

## Claims

### Claim 1

A pixel, comprising:
a light emitting element;
a first transistor connected between a first node and a second node and configured to generate a driving current flowing from a first power line providing a first power voltage to a second power line providing a second power voltage through the light emitting element;
a second transistor connected between a data line and the first node and configured to be turned on in response to a fourth scan signal supplied to a fourth scan line;
a third transistor connected between the second node and a third node corresponding to a gate electrode of the first transistor and configured to be turned on in response to a third scan signal supplied to a third scan line;
a fourth transistor connected between the third node and a third power line providing a third power voltage and configured to be turned on in response to a second scan signal supplied to a second scan line;
a fifth transistor connected between the first power line and the first node and configured to be turned off in response to an emission control signal supplied to an emission control line;
a sixth transistor connected between the second node and a fourth node corresponding to a first electrode of the light emitting element and configured to be turned off in response to the emission control signal;
a seventh transistor connected between the fourth node and a fourth power line providing a fourth power voltage and configured to be turned on in response to a first scan signal supplied to a first scan line; and
an eighth transistor connected between the first node and a fifth power line providing a fifth power voltage and configured to be turned on in response to the first scan signal,
wherein, during one frame period, the first scan signal is supplied to the first scan line at least twice during a first non-emission period and at least once during a second non-emission period, and
wherein, in the one frame period, a voltage level of the fourth power voltage varies,
wherein the one frame period comprises:
a first driving period in which the fourth scan signal is supplied to the second transistor, a data signal supplied to the data line is written, and the first scan signal is supplied to the eighth transistor; and
a second driving period in which the fourth scan signal is not supplied to the second transistor and the first scan signal is supplied to the eighth transistor.

### Claim 2 (depends on 1)

The pixel according to claim 1, wherein the first driving period comprises:
a first period in which the third scan signal is supplied to the third transistor and the first scan signal is supplied to the seventh transistor and the eighth transistor;
a second period in which the second scan signal is supplied to the fourth transistor after the first period;
a third period in which the third scan signal is supplied to the third transistor and the fourth scan signal is supplied to the second transistor after the second period; and
a fourth period in which the first scan signal is supplied to the seventh transistor and the eighth transistor after the third period.

### Claim 3 (depends on 2)

The pixel according to claim 2, wherein the fourth power voltage has a first voltage level in the first to third periods and a second voltage level different from the first voltage level in the fourth period.

### Claim 4 (depends on 3)

The pixel according to claim 3, wherein the second voltage level is greater than the first voltage level.

### Claim 5 (depends on 4)

The pixel according to claim 4, wherein the second voltage level is less than a value obtained by adding a threshold voltage of the light emitting element and the second power voltage.

### Claim 6 (depends on 2)

The pixel according to claim 2, wherein a width of the third scan signal is greater than a width of the first scan signal in the first period.

### Claim 7 (depends on 1)

The pixel according to claim 1, wherein the second driving period comprises a first period in which the first scan signal is supplied to the seventh transistor and the eighth transistor.

### Claim 8 (depends on 7)

The pixel according to claim 7, wherein the fourth power voltage is maintained as a first voltage level during the second driving period.

### Claim 9 (depends on 7)

The pixel according to claim 7, wherein the second driving period further comprises a second period in which the first scan signal is supplied to the seventh transistor and the eighth transistor after the first period.

### Claim 10 (depends on 9)

The pixel according to claim 9, wherein the fourth power voltage has a first voltage level in the first period and a second voltage level different from the first voltage level in the second period.

### Claim 11

A display device, comprising:
a pixel connected to first to fourth scan lines, an emission control line, a data line, and first to fifth power lines;
a scan driver configured to supply first to fourth scan signals to the first to fourth scan lines, respectively;
an emission driver configured to supply an emission control signal to the emission control line;
a data driver configured to supply a data signal to the data line; and
a power supply configured to supply first to fifth power voltages to the first to fifth power lines, respectively,
wherein the pixel comprises:
a light emitting element;
a first transistor connected between a first node and a second node and configured to generate a driving current flowing from the first power line to the second power line through the light emitting element;
a second transistor connected between the data line and the first node and configured to be turned on in response to the fourth scan signal;
a third transistor connected between the second node and a third node corresponding to a gate electrode of the first transistor and configured to be turned on in response to the third scan signal;
a fourth transistor connected between the third node and the third power line and configured to be turned on in response to the second scan signal;
a fifth transistor connected between the first power line and the first node and configured to be turned off in response to the emission control signal;
a sixth transistor connected between the second node and a fourth node corresponding to a first electrode of the light emitting element and configured to be turned off in response to the emission control signal;
a seventh transistor connected between the fourth node and the fourth power line and configured to be turned on in response to the first scan signal; and
an eighth transistor connected between the first node and the fifth power line and configured to be turned on in response to the first scan signal,
wherein the scan driver supplies the first scan signal to the first scan line at least twice during a first non-emission period and at least once during a second non-emission period during one frame period,
wherein the power supply varies a voltage level of the fourth power voltage in the one frame period,
wherein the one frame period comprises a first driving period and a second driving period,
wherein, in the first driving period, the scan driver supplies the first scan signal through the first scan line and supplies the fourth scan signal through the fourth scan line, and
wherein, in the second driving period, the scan driver supplies the first scan signal through the first scan line and does not supply the fourth scan signal.

### Claim 12 (depends on 11)

The display device according to claim 11, wherein the first driving period comprises:
a first period in which the scan driver supplies the first scan signal to the first scan line and supplies the third scan signal to the third scan line;
a second period in which the scan driver supplies the second scan signal to the second scan line after the first period;
a third period in which the scan driver supplies the third scan signal to the third scan line and the fourth scan signal to the fourth scan line after the second period; and
a fourth period in which the scan driver supplies the first scan signal to the first scan line after the third period.

### Claim 13 (depends on 12)

The display device according to claim 12, wherein the power supply supplies the fourth power voltage having a first voltage level to the fourth power line in the first to third periods, and supplies the fourth power voltage having a second voltage level different from the first voltage level to the fourth power line in the fourth period.

### Claim 14 (depends on 13)

The display device according to claim 13, wherein the second voltage level is greater than the first voltage level.

### Claim 15 (depends on 11)

The display device according to claim 11, wherein the second driving period comprises a first period in which the scan driver supplies the first scan signal to the first scan line, and
wherein the power supply supplies the fourth power voltage having a first voltage level to the fourth power line in the first period.

### Claim 16 (depends on 15)

The display device according to claim 15, wherein the second driving period further comprises a second period in which the scan driver supplies the first scan signal to the first scan line after the first period, and
wherein the power supply supplies the fourth power voltage having a second voltage level different from the first voltage level to the fourth power line in the second period.