Organic light emitting display device

• US 10,403,203 B2
• Filed: 05/12/2017
• Issued: 09/03/2019
• Est. Priority Date: 05/31/2016
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kim, JungChul
• Primary Examiner(s): Karimi, Pegeman
• Application Number:
  US15/594,056
• Publication Number:
  US 20170345368A1
• Time in Patent Office: 844 Days
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: 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
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 2320/046 Dealing with screen burn-in prevention or compensation of the effects thereof
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2370/047 using display data channel standard [DDC] communication
• CPC Class Codes: G09G 3/30 using electroluminescent panels
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/36 using liquid crystals

Abstract

The present disclosure relates to an organic light emitting display device which is implemented to reduce or suppress the residual image and the flicker. According to an embodiment, a circuit includes an organic light emitting diode disposed between a first node and a first power source, a driving transistor disposed between the first node and a second power source and driving the organic light emitting device, a first transistor transmitting a data signal to the driving transistor, and a first control transistor disposed between the first node and a second node. The first control transistor applies a reverse current to the driving transistor during a first period and holes accumulated on the active layer of the driving transistor are removed during the first period, whereby a current path efficiency is improved.

Claims

1. An organic light emitting display device, comprising:

an organic light emitting diode connected between a first node and a second power source;

a driving transistor disposed between the first node and a first power source, and driving the organic light emitting diode;

a first transistor configured to transmit a data signal to the driving transistor;

a first control transistor disposed between the first node and a second node;

a third node connected to a gate electrode of the first control transistor; and

a second transistor disposed between the third node and a third power source,

wherein the first control transistor is configured to be turned on during a first period,

wherein a voltage of the second node is higher than a voltage of the first power source during the first period, and

wherein the second transistor is configured to be turned on during the first period to discharge the third node.

2. The organic light emitting display device according to claim 1, wherein the first control transistor is configured to apply a reverse current to the driving transistor during the first period.

3. The organic light emitting display device according to claim 1, further comprising:

a third transistor disposed between a fourth power source and the second node.

4. The organic light emitting display device according to claim 3, wherein the third transistor is configured to charge the second node with a voltage of the fourth power source during the first period.

5. The organic light emitting display device according to claim 3, further comprising:

a fourth transistor connected to the second node and configured to transmit a voltage of the second node to a drain electrode of the fourth transistor during a second period.

6. The organic light emitting display device according to claim 5, wherein the first period and the second period are configured so as not to temporally overlap each other.

7. The organic light emitting display device according to claim 1, further comprising:

a fourth node connected to a cathode electrode of the organic light emitting diode; and

a multiplexer unit disposed between the fourth node and the second power source,

wherein the multiplexer unit is configured to convert the fourth node to be at a high impedance status or a floating status during the first period.

8. The organic light emitting display device according to claim 1, further comprising:

a second control transistor disposed between the first node and the organic light emitting diode.

9. The organic light emitting display device according to claim 8, wherein the second control transistor is turned off during the first period and controls a current so as not to flow into the organic light emitting diode.

10. An organic light emitting display device, comprising:

an organic light emitting diode connected between a first node and a second power source;

a driving transistor disposed between the first node and a first power source, and configured to drive the organic light emitting diode;

a first transistor configured to transmit a data signal to the driving transistor; and

a first control transistor configured to control a current to be applied to the driving transistor,

wherein the first control transistor and the first transistor are commonly connected to the second node, and

wherein the first control transistor is configured to apply a reverse current to the driving transistor during a first period and a current path efficiency of the driving transistor is improved during the first period, whereby residual image and flicker characteristics are reduced.

11. The organic light emitting display device according to claim 10, wherein a voltage of the second node is higher than a voltage of the first power source during the first period.

12. The organic light emitting display device according to claim 10, further comprising:

a third node connected to a gate electrode of the first control transistor; and

a second transistor configured to discharge the third node during the first period.

13. The organic light emitting display device according to claim 10, further comprising:

a third transistor configured to charge a compensation voltage to the second node during the first period,

wherein the compensation voltage is higher than the voltage of the first power source.

14. The organic light emitting display device according to claim 13, further comprising:

a fifth transistor configured to charge the data signal to the second node during the second period,

wherein the first period and the second period are configured without overlapping at a same time.

15. The organic light emitting display device according to claim 14, further comprising:

a fourth transistor configured to sense a voltage of the second node during a third period,

wherein the third period is configured without overlapping at the same time with the first period and the second period.

16. The organic light emitting display device according to claim 10, further comprising:

a second control transistor between the first power source and the second power source,

wherein the second control transistor is configured to control the organic light emitting diode to emit light.

17. The organic light emitting display device according to claim 16, wherein the second control transistor is disposed between the first power source and the driving transistor, and a cathode electrode of the organic light emitting diode is configured to be maintained at a high impedance status during the first period.

18. The organic light emitting display device according to claim 16, wherein the second control transistor is disposed between the first node and the organic light emitting diode and is configured to be turned off during the first period.