# US 8,786,587 B2 · Pixel and organic light emitting display using the same

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- Number: US 8,786,587 B2
- Document ID: US8786587B2
- Status: Granted
- Kind: B2
- Application number: 12/698,399
- Filed: 2010-02-02
- Published: 2010-12-09
- Granted: 2014-07-22
- Earliest claimed: 2009-06-05
- Assignees: Samsung Display Co., Ltd.
- Applicants: Chul-Kyu Kang; Yu-Lian Choi; Keum-Nam Kim
- Inventors: Chul-Kyu Kang; Yu-Lian Choi; Keum-Nam Kim
- Web page: https://patentgrep.com/patent/US8786587B2

## CPC

- G09G 3/3233: with pixel circuitry controlling the current through the light-emitting element
- 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 2300/0852: being a dynamic memory with more than one capacitor
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- G09G 2320/043: Preventing or counteracting the effects of ageing
- 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 includes an organic light emitting diode (OLED) having a cathode electrode coupled to a second power source, a first transistor for controlling an amount of current that flows from a first power source to the second power source via the OLED corresponding to a data signal, a second transistor coupled between a data line and a gate electrode of the first transistor, a third transistor coupled between the gate electrode of the first transistor and a reference power source, a fourth transistor coupled between the third transistor and the reference power source, a fifth transistor coupled between an anode electrode of the OLED and an initial power source, a first capacitor coupled between the anode electrode of the OLED and a node between the third transistor and the fourth transistor, and a second capacitor coupled between the node and the gate electrode of the first transistor.

## Claims

### Claim 1

A pixel, comprising:
an organic light emitting diode (OLED) having a cathode electrode coupled to a second power source;
a first transistor for controlling an amount of current that flows from a first power source to the second power source via the OLED corresponding to a data signal;
a second transistor coupled between a data line and a gate electrode of the first transistor and turned on when a scan signal is supplied to a scan line;
a third transistor coupled between the gate electrode of the first transistor and a reference power source and turned off when an emission control signal is supplied to an emission control line;
a fourth transistor coupled between the third transistor and the reference power source and turned on when a control signal is supplied to a control line;
a fifth transistor coupled between an anode electrode of the OLED and an initial power source different from the and turned on when the scan signal is supplied to the scan line;
a first capacitor coupled between the anode electrode of the OLED and a node between the third transistor and the fourth transistor; and
a second capacitor coupled between the node and the gate electrode of the first transistor.

### Claim 2 (depends on 1)

The pixel as claimed in claim 1, wherein the second transistor and the fifth transistor are on for a portion of a period in which the fourth transistor is on.

### Claim 3 (depends on 2)

The pixel as claimed in claim 2, wherein the second transistor and the fifth transistor are configured to be turned on when the fourth transistor is turned on.

### Claim 4 (depends on 2)

The pixel as claimed in claim 2, wherein the third transistor is off when the fourth transistor is on.

### Claim 5 (depends on 1)

The pixel as claimed in claim 1, wherein the reference power source has a voltage equal to or higher than a voltage of the data signal.

### Claim 6 (depends on 5)

The pixel as claimed in claim 5, wherein the initial power source has a voltage lower than the voltage of the data signal.

### Claim 7 (depends on 6)

The pixel as claimed in claim 6, wherein the voltage of the initial power source is lower than a voltage obtained by subtracting a threshold voltage of the first transistor from the voltage of the data signal.

### Claim 8 (depends on 5)

The pixel as claimed in claim 5, wherein the first power source has a voltage higher than the voltage of the reference power source.

### Claim 9

An organic light emitting display, comprising:
a scan driver for sequentially supplying a scan signal to scan lines, sequentially supplying an emission control signal to emission control lines, and sequentially supplying a control signal to control lines;
a data driver for supplying a data signal to data lines corresponding to the scan signal; and
pixels at crossing regions of the scan lines and the data lines,
wherein a pixel positioned on an ith (i is a natural number) horizontal line from among the pixels comprises:
an organic light emitting diode (OLED) having a cathode electrode coupled to a second power source;
a first transistor for controlling an amount of current that flows from a first power source to the second power source via the OLED corresponding to the data signal;
a second transistor coupled between the data line and a gate electrode of the first transistor and turned on when the scan signal is supplied to an ith scan line of the scan lines;
a third transistor coupled between the gate electrode of the first transistor and a reference power source and turned off when the emission control signal is supplied to an ith emission control line of the emission control lines;
a fourth transistor coupled between the third transistor and the reference power source and turned on when the control signal is supplied to an ith control line of the control lines;
a fifth transistor coupled between an anode electrode of the OLED and an initial power source different from the first power source and turned on when the scan signal is supplied to the ith scan line;
a first capacitor coupled between the anode electrode of the OLED and a node between the third transistor and the fourth transistor; and
a second capacitor coupled between the node and the gate electrode of the first transistor.

### Claim 10 (depends on 9)

The organic light emitting display as claimed in claim 9, wherein the scan driver is configured to supply the scan signal to the ith scan line when the control signal is supplied to the ith control line.

### Claim 11 (depends on 10)

The organic light emitting display as claimed in claim 10, wherein the control signal has a longer duration than the scan signal.

### Claim 12 (depends on 10)

The organic light emitting display as claimed in claim 10, wherein the scan driver is configured to supply the emission control signal to the ith emission control line when the control signal is supplied to the ith control line.

### Claim 13 (depends on 9)

The organic light emitting display as claimed in claim 9, wherein the reference power source has a voltage equal to or higher than a voltage of the data signal.

### Claim 14 (depends on 13)

The organic light emitting display as claimed in claim 13, wherein the initial power source has a voltage lower than the voltage of the data signal.

### Claim 15 (depends on 14)

The organic light emitting display as claimed in claim 14, wherein the voltage of the initial power source is lower than a voltage obtained by subtracting a threshold voltage of the first transistor from the voltage of the data signal.

### Claim 16 (depends on 13)

The organic light emitting display as claimed in claim 13, wherein the first power source has a voltage higher than the voltage of the reference power source.