# US 9,437,142 B2 · Pixel circuit and display apparatus

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- Number: US 9,437,142 B2
- Document ID: US9437142B2
- Status: Granted
- Kind: B2
- Application number: 14/443,686
- Filed: 2014-09-26
- Published: 2016-06-23
- Granted: 2016-09-06
- Earliest claimed: 2014-06-13
- Assignees: Boe Technology Group Co., Ltd.; Beijing Boe Technology Co., Ltd.
- Applicants: Boe Technology Group Co., Ltd.; Beijing Boe Optoelectronics Technology Co., Ltd.
- Inventors: Shengji Yang; Xue Dong; Haisheng Wang
- Web page: https://patentgrep.com/patent/US9437142B2

## CPC

- 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 3/3225: using an active matrix
- G09G 3/3233: with pixel circuitry controlling the current through the light-emitting element
- G09G 3/3266: Details of drivers for scan electrodes
- G09G 2300/0443: with several sub-pixels for the same colour in a pixel, not specifically used to display gradations (G09G3/364 takes precedence)
- G09G 2300/0465: Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
- G09G 2300/0804: Sub-multiplexed active matrix panel, i.e. wherein one active driving circuit is used at pixel level for multiple image producing elements
- 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 2310/0262: 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 2320/0233: 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)

## Abstract

A pixel circuit, comprises two sub-pixel circuits (P1, P2) and a sixth switch unit (T6); a first terminal of the sixth switch unit (T6) is connected to an operating voltage line (Vdd), and a control terminal of the sixth switch unit is connected to a first scan signal line (Em); each of the sub-pixel circuits (P1, P2) comprises five switch units (T1, T2, T3, T4, T5), a driving unit (DT), a energy storage unit (C) and an electroluminescent unit (L), a first switch unit (T1) and a fourth switch unit (T4) in a first sub-pixel circuit (P1) share a scan signal line (Scan[3]) with a first switch unit (T1′) and a fourth switch unit (T4′) in a second sub-pixel circuit (P2), and a third switch unit (T3) in the first sub-pixel circuit (P1) share a scan signal line (Scan[2]) with a third switch unit (T3′) in the second sub-pixel circuit (P2). The pixel circuit completely solves the problem of non-uniformity in the display brightness due to drifting of the threshold voltage of the driving transistor. Meanwhile, one compensation circuit is used to drive two pixels, and two adjacent pixels share multiple signal lines, which can reduce the number of signal lines for the pixel circuit in a display apparatus, lower the cost of the integration circuit, decrease the pixel pitch, and increase the pixel density.

## Claims

### Claim 1

A pixel circuit comprising two sub-pixel circuits, wherein
each of the sub-pixel circuits comprises a first to a fifth switch units, a driving unit, an energy storage unit and an electroluminescent unit;
a first terminal of the first switch unit is connected to a first terminal of the energy storage unit, a second terminal of the first switch unit is grounded, and the first switch unit is configured to ground the first terminal of the energy storage unit under the control of a scan signal line connected to a control terminal of the first switch unit;
a first terminal of the second switch unit is connected to a data voltage line, a second terminal of the second switch unit is connected to the first terminal of the energy storage unit, and the second switch unit is configured to write the voltage in the data voltage line into the first terminal of the energy storage unit under the control of a scan signal line connected to a control terminal of the second switch unit;
a first terminal of the third switch unit is connected to the second terminal of the energy storage unit, a second terminal of the third switch unit is grounded, and the third switch unit is configured to ground the second terminal of the energy storage unit under the control of a scan signal line connected to a control terminal of the third switch unit;
a first terminal of the fourth switch unit is connected to an output terminal of the driving unit, a second terminal of the fourth switch unit is connected to the second terminal of the energy storage unit, and the forth switch unit is configured to connect the output terminal of the driving unit to a control terminal of the driving unit under the control of a scan signal line connected to a control terminal of the fourth switch unit;
a first terminal of the fifth switch unit is connected to the output terminal of the driving unit, a second terminal of the fifth switch unit is connected to the electroluminescent unit, and the first switch unit is configured to introduce a driving current provided by the driving unit into the electroluminescent unit under the control of a scan signal line connected to a control terminal of the fifth switch unit;
the control terminal of the driving unit is connected to the second terminal of the energy storage unit;
in the two sub-pixel circuits, the control terminals of the first switch unit and the fourth switch unit are connected to a third scan signal line, and the control terminals of the third switch unit are connected to a second scan signal line; the control terminals of the second switch unit and the fifth switch unit in a first sub-pixel circuit are connected to a first scan signal line, and the control terminals of the second switch unit and the fifth switch unit in a second sub-pixel circuit are connected to a fourth scan signal line;
the pixel circuit further comprises a sixth switch unit, a first terminal of which is connected to an operating voltage line, a second terminal of which is connected to the input terminals of the driving units of the two sub-pixel circuits respectively, and a control terminal of which is connected to a fifth scan signal line, and the sixth switch unit is configured to provide an operating voltage for the driving unit under the control of the fifth scan signal line.

### Claim 2 (depends on 1)

The pixel circuit according to claim 1, wherein the switch units and the driving units are thin film transistors, the control terminal of each switch unit is a gate of the thin film transistor, the first terminal of each switch unit is a source of the thin film transistor, the second terminal of each switch unit is a drain of the thin film transistor, the input terminal of the driving unit is a source of the thin film transistor, the control terminal of the driving unit is a gate of the thin film transistor, and the output terminal of the driving unit is a drain of the thin film transistor.

### Claim 3 (depends on 2)

The pixel circuit according to claim 2, wherein all of the respective thin film transistors are of P channel type.

### Claim 4 (depends on 1)

The pixel circuit according to claim 1, wherein the energy storage unit is a capacitor.

### Claim 5 (depends on 1)

The pixel circuit according to claim 1, wherein the electroluminescent unit is an organic light emitting diode.

### Claim 6 (depends on 1)

A display apparatus comprising the pixel circuit according to claim 1.

### Claim 7 (depends on 6)

The display apparatus according to claim 6, wherein two sub-pixel circuits of the pixel circuit are located respectively within two adjacent pixels.

### Claim 8 (depends on 7)

The display apparatus according to claim 7, wherein the two adjacent pixels are located respectively at two sides of the data voltage line.

### Claim 9 (depends on 7)

The display apparatus according to claim 7, wherein the two adjacent pixels are located at a same side of the data voltage line.

### Claim 10 (depends on 2)

The pixel circuit according to claim 2, wherein the energy storage unit is a capacitor.

### Claim 11 (depends on 3)

The pixel circuit according to claim 3, wherein the energy storage unit is a capacitor.

### Claim 12 (depends on 2)

The pixel circuit according to claim 2, wherein the electroluminescent unit is an organic light emitting diode.

### Claim 13 (depends on 3)

The pixel circuit according to claim 3, wherein the electroluminescent unit is an organic light emitting diode.

### Claim 14 (depends on 4)

The pixel circuit according to claim 4, wherein the electroluminescent unit is an organic light emitting diode.

### Claim 15 (depends on 10)

The pixel circuit according to claim 10, wherein the electroluminescent unit is an organic light emitting diode.

### Claim 16 (depends on 11)

The pixel circuit according to claim 11, wherein the electroluminescent unit is an organic light emitting diode.

### Claim 17 (depends on 6)

The display apparatus according to claim 6, wherein the switch units and the driving units are thin film transistors, the control terminal of each switch unit is a gate of the thin film transistor, the first terminal of each switch unit is a source of the thin film transistor, the second terminal of each switch unit is a drain of the thin film transistor, the input terminal of the driving unit is a source of the thin film transistor, the control terminal of the driving unit is a gate of the thin film transistor, and the output terminal of the driving unit is a drain of the thin film transistor.

### Claim 18 (depends on 17)

The display apparatus according to claim 17, wherein all of the respective thin film transistors are of P channel type.

### Claim 19 (depends on 6)

The display apparatus according to claim 6, wherein the energy storage unit is a capacitor.

### Claim 20 (depends on 6)

The display apparatus according to claim 6, wherein the electroluminescent unit is an organic light emitting diode.