# US 12,112,698 B2 · Pixel circuit, display device, and method of driving pixel circuit

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- Number: US 12,112,698 B2
- Document ID: US12112698B2
- Status: Granted
- Kind: B2
- Application number: 17/977,023
- Filed: 2022-10-31
- Published: 2023-02-16
- Granted: 2024-10-08
- Earliest claimed: 2003-05-23
- Assignees: Sony Group Corporation
- Applicants: Sony Group Corporation
- Inventors: Katsuhide Uchino; Junichi Yamashita; Tetsuro Yamamoto
- Web page: https://patentgrep.com/patent/US12112698B2

## CPC

- G09G 3/3233: with pixel circuitry controlling the current through the light-emitting element
- G09G 3/30: using electroluminescent panels
- G09G 3/3258: with pixel circuitry controlling the voltage across the light-emitting element
- G09G 3/3426: {the different display panel areas being distributed in two dimensions, e.g. matrix}
- G09G 3/36: using liquid crystals
- G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)}
- H05B 45/60: Circuit arrangements for operating LEDs comprising organic material, e.g. for operating organic light-emitting diodes [OLED] or polymer light-emitting diodes [PLED]
- 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 2300/0809: Several active elements per pixel in active matrix panels
- 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 2310/0256: with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- 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: 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)
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL

## Abstract

A pixel circuit, display device, and method of driving a pixel circuit enabling source-follower output with no deterioration of luminance even with a change of the current-voltage characteristic of the light emitting element along with elapse, enabling a source-follower circuit of n-channel transistors, and able to use an n-channel transistor as an EL drive transistor while using current anode-cathode electrodes. The circuit includes a source of a TFT used as a drive transistor that is connected to an anode of a light emitting element, and a drain of the TFT is connected to a power source potential. A capacitor is connected between a gate and source of the TFT, and a source potential of the TFT is connected to a fixed potential through a TFT used as a switching transistor.

## Claims

### Claim 1

A display device comprising:
a plurality of pixel circuits; and
control circuitry configured to drive the plurality of pixel circuits, wherein
at least one of the plurality of pixel circuits includes
a light emitting element,
a capacitor,
a first transistor configured to supply a signal voltage supplied through a data signal line to the capacitor,
a drive transistor configured to supply driving current to the light emitting element according to the signal voltage stored in the capacitor,
a second transistor electrically connected between the drive transistor and the light emitting element, and
a third transistor electrically directly connected to a gate of the drive transistor.

### Claim 2 (depends on 1)

The display device according to claim 1, wherein the third transistor is electrically directly connected to a first voltage line.

### Claim 3 (depends on 2)

The display device according to claim 2, wherein the drive transistor is configured to supply the driving current from the first voltage line to the light emitting element according to the signal voltage stored in the capacitor.

### Claim 4 (depends on 1)

The display device according to claim 1, further comprising a fourth transistor electrically directly connected to the drive transistor.

### Claim 5 (depends on 4)

The display device according to claim 4, wherein the fourth transistor is electrically connected between the drive transistor and the second transistor.

### Claim 6 (depends on 4)

The display device according to claim 4, wherein
a gate of the first transistor is electrically connected to a first control line,
a gate of the second transistor is electrically connected to a second control line,
a gate of the third transistor is electrically connected to a third control line, and
a gate of the fourth transistor is electrically connected to a fourth control line.

### Claim 7 (depends on 4)

The display device according to claim 4, wherein each of the first transistor, the second transistor, the drive transistor, the third transistor, and the fourth transistor is constituted by an n-channel transistor.

### Claim 8 (depends on 1)

The display device according to claim 1, wherein a cathode electrode of the light emitting element is electrically directly connected to a second voltage line.

### Claim 9 (depends on 1)

The display device according to claim 1, wherein
a gate of the first transistor is electrically connected to a first control line,
a gate of the second transistor is electrically connected to a second control line, and
a gate of the third transistor is electrically connected to a third control line.

### Claim 10 (depends on 1)

The display device according to claim 1, wherein each of the first transistor, the second transistor, the drive transistor, and the third transistor is constituted by an n-channel transistor.