# US 12,603,059 B2 · Display device

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- Number: US 12,603,059 B2
- Document ID: US12603059B2
- Status: Granted
- Kind: B2
- Application number: 18/045,570
- Filed: 2022-10-11
- Published: 2023-05-04
- Granted: 2026-04-14
- Earliest claimed: 2021-11-02
- Assignees: Samsung Display Co., Ltd.
- Applicants: Samsung Display Co., Ltd.
- Inventors: Jaehoon Lee; Dae-Seop Kim; Cheolmin Kim; Byung Ki Chun
- Web page: https://patentgrep.com/patent/US12603059B2

## CPC

- G09G 3/3275: Details of drivers for data electrodes
- G09G 3/3233: with pixel circuitry controlling the current through the light-emitting element
- G09G 3/2003: {Display of colours (specific for liquid crystal displays G09G3/3607)}
- G09G 2300/0413: Details of dummy pixels or dummy lines in flat panels
- G09G 2300/043: Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
- G09G 2300/0819: used for counteracting undesired variations, e.g. feedback or autozeroing
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- G09G 2320/0271: Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
- G09G 2320/029: by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
- G09G 2320/0295: by monitoring each display pixel
- G09G 2320/043: Preventing or counteracting the effects of ageing
- G09G 2320/045: Compensation of drifts in the characteristics of light emitting or modulating elements
- G09G 2340/00: Aspects of display data processing
- 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 display device may compensate for such changes in characteristics of light emitting elements and transistors in pixels of a display. For example, a driving circuit of a display device may update a lookup table that stores one or more compensation values. Each compensation value may correspond to a characteristic change of a pixel. In some embodiments, the characteristic change of a transistor may be determined based on a sensing signal received from a dummy pixel. Accordingly, a display device may generate a compensation signal based on an actual characteristic change of the transistor in the pixel. The compensation signal may be used by the display device to compensate for pixel characteristic changes that occur over time. For instance, a display device may use such compensation signals to correct input signals (e.g., to generate a corrected output signal) to be applied to one or more pixels of a display.

## Claims

### Claim 1

A display device comprising:
a display panel comprising a pixel positioned in an active area and a dummy pixel positioned in an inactive area adjacent to the active area;
a driving controller configured to output an output image signal to a data driving circuit based on a sensing signal received from the dummy pixel; and
the data driving circuit configured to provide the pixel and the dummy pixel with a data signal corresponding to the output image signal via a same data line,
wherein the driving controller comprises:
a first accumulator configured to accumulate the output image signal and to output a first accumulation signal;
a first lookup table configured to store a compensation value, the compensation value corresponding to a grayscale level of an input image signal and an operating time of the pixel;
a sensing compensator configured to correct the compensation value stored in the first lookup table based on the sensing signal received from the dummy pixel;
a first compensator configured to output a first compensation signal based on the input image signal, the first accumulation signal, and the compensation value stored in the first lookup table; and
an adder configured to output the output image signal by adding the first compensation signal to the input image signal,
wherein the sensing compensator comprises:
a compensation grayscale calculator configured to calculate a compensation grayscale corresponding to the sensing signal;
a sensing accumulator configured to accumulate the sensing signal and to output operating time information corresponding to an operating time of the dummy pixel;
a reference value storage configured to store predicted compensation reference values corresponding to an operating time of the dummy pixel and output a compensation reference value corresponding to the operating time information; and
a compensation value calculator configured to calculate a difference value between the compensation grayscale and the compensation reference value and to output a correction value for correcting the compensation value stored in the first lookup table, wherein the correction value corresponds to the calculated difference value, and
wherein the compensation reference value is one of the predicted compensation reference values.

### Claim 2 (depends on 1)

The display device of claim 1, wherein the pixel includes:
a first transistor electrically connected between a first voltage line and a first node, wherein the first transistor comprises a gate electrode configured to receive the data signal from the data driving circuit; and
a light emitting element electrically connected between the first node and a second voltage line.

### Claim 3 (depends on 2)

The display device of claim 2, wherein the first compensation signal comprises a signal for compensating for a current at the first node according to a characteristic change of the first transistor.

### Claim 4 (depends on 2)

The display device of claim 2, wherein the driving controller further includes:
a second accumulator configured to accumulate the output image signal and output a second accumulation signal; and
a second compensator configured to output a second compensation signal corresponding to the input image signal and the second accumulation signal,
wherein the adder is configured to output the output image signal by adding the first compensation signal and the second compensation signal to the input image signal.

### Claim 5 (depends on 4)

The display device of claim 4, wherein the second compensation signal comprises a signal for compensating for a characteristic change of the light emitting element.

### Claim 6 (depends on 4)

The display device of claim 4, wherein the first compensator receives the second accumulation signal from the second compensator, calculates a voltage correction coefficient based on the second accumulation signal, changes the grayscale level of the input image signal into a grayscale level corresponding to the voltage correction coefficient, and outputs the first compensation signal corresponding to the changed grayscale level and the first accumulation signal based on the compensation value from the first lookup table.

### Claim 7 (depends on 6)

The display device of claim 6, wherein the voltage correction coefficient is proportional to the operating time of the pixel.

### Claim 8 (depends on 1)

The display device of claim 1, wherein the dummy pixel includes:
a first transistor electrically connected between a first voltage line and a first node, wherein the first transistor comprises a gate electrode configured to receive the data signal; and
a light emitting element electrically connected between the first node and a second voltage line.

### Claim 9 (depends on 8)

The display device of claim 8, wherein the sensing signal corresponds to a current at the first node.

### Claim 10 (depends on 1)

The display device of claim 1, wherein the driving controller further includes:
a second lookup table configured to store a correction value according to a location of the pixel in the display panel,
wherein the first accumulator outputs the first accumulation signal corresponding to the output image signal based on referencing the correction value stored in the second lookup table.

### Claim 11

A display device comprising:
a display panel comprising a pixel positioned in an active area and a dummy pixel positioned in an inactive area adjacent to the active area;
a driving controller configured to output an output image signal based on an input image signal and a sensing signal, wherein the sensing signal is received from the dummy pixel; and
a data driving circuit configured to provide the pixel and the dummy pixel with a data signal corresponding to the output image signal,
wherein the pixel includes a light emitting element and a transistor electrically connected to the light emitting element,
wherein the driving controller comprises:
a first compensation block configured to output: a first compensation signal for compensating for a characteristic change of the transistor based on the input image signal, a first accumulation signal from accumulating the output image signal, and the sensing signal from the dummy pixel, wherein the first accumulation signal indicates a stress level of the transistor;
a second compensation block configured to output a second compensation signal for compensating for a characteristic change of the light emitting element based on the input image signal and a second accumulation signal from accumulating the output image signal, wherein the second accumulation signal indicates a stress level of the light emitting element; and
an adder configured to output the output image signal by adding the input image signal, the first compensation signal, and the second compensation signal,
wherein the first compensation block includes:
a first lookup table configured to store a compensation value, the compensation value corresponding to a grayscale level of the input image signal and an operating time of the pixel; and
a sensing compensator configured to correct the compensation value stored in the first lookup table based on the sensing signal from the dummy pixel,
wherein the sensing compensator includes:
a compensation grayscale calculator configured to calculate a compensation grayscale corresponding to the sensing signal;
a sensing accumulator configured to accumulate the sensing signal and output operating time information corresponding to an operating time of the dummy pixel;
a reference value storage configured to store predicted compensation reference values corresponding to an operating time of the dummy pixel and output a compensation reference value corresponding to the operating time information; and
a compensation value calculator configured to:
calculate a difference value between the compensation grayscale and the compensation reference value, and
output a correction value for correcting the compensation value stored in the first lookup table, wherein the correction value corresponds to the difference value, and
wherein the compensation reference value is one of the predicted compensation reference values.

### Claim 12 (depends on 11)

The display device of claim 11, wherein the first compensation block includes:
a first accumulator configured to accumulate the output image signal and output the first accumulation signal;
and
a first compensator configured to output the first compensation signal, the first compensation signal corresponding to the input image signal and the first accumulation signal based on the compensation value stored in the first lookup table.

### Claim 13 (depends on 12)

The display device of claim 12, wherein the second compensation block includes:
a second accumulator configured to accumulate the output image signal and output the second accumulation signal; and
a second compensator configured to output the second compensation signal corresponding to the input image signal and the second accumulation signal.

### Claim 14 (depends on 13)

The display device of claim 13, wherein the first compensator receives the second accumulation signal from the second compensator, calculates a voltage correction coefficient according to the second accumulation signal, changes a grayscale level of the input image signal into a grayscale level corresponding to the voltage correction coefficient, and outputs the first compensation signal corresponding to the changed grayscale level and the first accumulation signal based on referencing the compensation value from the first lookup table.

### Claim 15 (depends on 14)

The display device of claim 14, wherein the voltage correction coefficient is proportional to the operating time of the pixel.

### Claim 16 (depends on 11)

The display device of claim 11, wherein the dummy pixel includes:
a first transistor electrically connected between a first voltage line and a first node, wherein the first transistor includes a gate electrode configured to receive the data signal; and
a light emitting element electrically connected between the first node and a second voltage line.

### Claim 17 (depends on 16)

The display device of claim 16, wherein the sensing signal corresponds to a current at the first node.

### Claim 18 (depends on 11)

The display device of claim 11, wherein the driving controller further includes:
a second lookup table configured to store a correction value according to a location of the pixel in the display panel, and
wherein the first accumulator outputs the first accumulation signal corresponding to the output image signal based on referencing the correction value stored in the second lookup table.