PIXEL, DISPLAY DEVICE INCLUDING THE SAME, AND DRIVING METHOD THEREOF

• US 20140139502A1
• Filed: 03/01/2013
• Published: 05/22/2014
• Est. Priority Date: 11/20/2012
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: HAN, Sang-Myeon
• Granted Patent: US 9,159,265 B2
• Time in Patent Office: Days
• US Class Current: 345/212
• CPC Class Codes: 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
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: 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
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/003 to produce spatial visual effects
• 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 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T

Abstract

A display device includes a plurality of pixels including a first capacitor connected between a data line and a first node, a switching transistor connecting the first node and a second node, a first light emitting transistor transmitting a first power source voltage to the second node, a driving transistor having one electrode connected to the second node and controlling a driving current flowing to an organic light emitting diode (OLED), and a reference voltage transistor transmitting a reference voltage to the first node, wherein, when the first power source voltage is applied to the second node through the first light emitting transistor such that a light emitting step in which the OLED emits light is simultaneously performed in a plurality of pixels.

Claims

1. A display device comprising:

a plurality of pixels including;

a first capacitor connected between a data line and a first node;

a switching transistor connecting the first node and a second node;

a first light emitting transistor transmitting a first power source voltage to the second node;

a driving transistor having one electrode connected to the second node and controlling a driving current flowing to an organic light emitting diode (OLED); and

a reference voltage transistor transmitting a reference voltage to the first node, wherein, when the first power source voltage is applied to the second node through the first light emitting transistor such that a light emitting step in which the organic light emitting diode (OLED) emits light is simultaneously performed in a plurality of pixels, the switching transistor is turned off and the reference voltage transistor is turned on such that the reference voltage is transmitted to the first node, and a data voltage corresponding to a scan signal of a gate-on voltage respectively corresponding to a plurality of pixels is stored to the first capacitor.

2. The display device of claim 1, wherein the reference voltage transistor is turned on by a scan signal of the gate-on voltage such that the reference voltage is transmitted to the first node.

3. The display device of claim 2, further comprising a second switching transistor that is turned on by the scan signal of the gate-on voltage to transmit the data voltage to the first capacitor.

4. The display device of claim 2, wherein the plurality of pixels further include a compensation transistor connecting the gate electrode and the other electrode of the driving transistor.

5. The display device of claim 4, wherein the plurality of pixels further include an initialization transistor connected to the gate electrode of the driving transistor.

6. The display device of claim 5, wherein the plurality of pixels further include a second light emitting transistor connected to the other electrode of the driving transistor and an anode of the organic light emitting diode (OLED).

7. The display device of claim 6, wherein the initialization transistor includes a gate electrode applied with an initialization signal, one electrode connected to the data line, and the other electrode connected to the gate electrode of the driving transistor.

8. The display device of claim 7, wherein when the initialization signal of the gate-on voltage is applied to the gate electrode of the initialization transistor, the initialization voltage is applied to the data line.

9. The display device of claim 8, wherein the plurality of pixels further include a second initialization transistor including a gate electrode applied with the initialization signal, one electrode connected to the first power source voltage, and the other electrode connected to the second node.

10. The display device of claim 6, wherein the initialization transistor includes a gate electrode applied with the initialization signal, one electrode applied with the initialization voltage, and the other electrode connected to the gate electrode of the driving transistor.

11. The display device of claim 10, further comprising a second initialization transistor including a gate electrode applied with the initialization signal, one electrode connected to the first power source voltage, and the other electrode connected to the second node.

12. The display device of claim 6, wherein when a compensation control signal of the gate-on voltage is applied to the gate electrode of the compensation transistor, the data line is applied with a sustain voltage and the compensation control signal of the gate-on voltage is applied to the gate electrode of the switching transistor gate electrode such that the data voltage that was stored to the first capacitor is transmitted to the second node with reference to the sustain voltage.

13. The display device of claim 12, wherein the data voltage that was stored to the first capacitor is the data voltage that is applied in a frame previous to a current frame.

14. The display device of claim 13, wherein the plurality of pixels further include a second capacitor connected between the gate electrode of the driving transistor and the first power source voltage to store a voltage reflecting the data voltage of the previous frame.

15. A method of driving a display device respectively including a plurality of pixels including a first capacitor connected between a data line and a first node, a switching transistor connecting the first node and a second node, a first light emitting transistor transmitting a first power source voltage to the second node, a driving transistor having one electrode connected to the second node and controlling a driving current flowing to the organic light emitting diode (OLED), and a reference voltage transistor transmitting a reference voltage to the first node, the method comprising:

a scan step in which the data voltage transmitted through the data line is stored to the first capacitor when the switching transistor is turned off and the scan signal of the gate-on voltage is transmitted to the reference voltage transistor; and

a light emitting step in which the first power source voltage is applied to the second node through the first light emitting transistor such that an organic light emitting diode (OLED) emits light, such that each light emitting step of the plurality of pixels is a simultaneous period, and the scan step and the light emitting step are temporally overlapped with each other.

16. The method of claim 15, wherein the scan step includes a step in which the scan signal of the gate-on voltage is applied to the gate electrode of the second switching transistor connecting the data line and the first capacitor to transmit the data voltage to the first capacitor.

17. The method of claim 15, wherein the light emitting step includes:

a step in which the first light emitting transistor transmitting the first power source voltage to one electrode of the driving transistor is turned on; and

a step in which the second light emitting transistor connected between the other electrode of the driving transistor and an anode of the organic light emitting diode (OLED) is turned on.

18. The method of claim 15, further comprising an initialization step in which an initialization signal of the gate-on voltage is applied to the gate electrode of the initialization transistor connected to the gate electrode of the driving transistor to transmit the initialization voltage to the gate electrode of the driving transistor.

19. The method of claim 18, wherein the initialization step includes a step in which the initialization signal of the gate-on voltage is applied to the gate electrode of the initialization transistor, wherein the initialization transistor includes one electrode connected to the data line and the other electrode connected to the gate electrode of the driving transistor.

20. The method of claim 19, wherein the initialization step includes a step in which the second initialization transistor including a gate electrode applied with the initialization signal, one electrode connected to the first power source voltage, and the other electrode connected to the second node is turned on.

21. The method of claim 18, wherein the initialization step includes a step in which an initialization signal of a gate-on voltage is applied to the gate electrode of the initialization transistor, wherein the initialization transistor includes one electrode applied with the initialization voltage and the other electrode connected to the gate electrode of the driving transistor.

22. The method of claim 21, wherein the initialization step includes a step in which the second initialization transistor including a gate electrode applied with the initialization signal, one electrode connected to the first power source voltage, and the other electrode connected to the second node is turned on.

23. The method of claim 15, further comprising a compensation step in which a compensation control signal of the gate-on voltage is applied to the gate electrode of the compensation transistor connecting the gate electrode and the other electrode of the driving transistor to compensate the threshold voltage of the driving transistor.

24. The method of claim 23, wherein the compensation step includes a step in which a sustain voltage is applied to the data line and the compensation control signal of the gate-on voltage is applied to the gate electrode of the switching transistor to transmit the data voltage stored to the first capacitor to the second node with reference of the sustain voltage when the compensation control signal of the gate-on voltage is applied to the gate electrode of the compensation transistor.

25. The method of claim 24, wherein the data voltage stored to the first capacitor is a data voltage applied in a frame previous to a current frame.

26. The method of claim 25, wherein the compensation step includes a step in which the compensation transistor is turned on, and a voltage reflecting the threshold voltage of the driving transistor and the data voltage of the previous frame is stored to the second capacitor connected to the gate electrode of the driving transistor and the first power source voltage.

27. A pixel comprising:

a first capacitor including one electrode applied with a data voltage and the other electrode connected to a first node;

a reference voltage transistor including a gate electrode applied with a scan signal, one electrode connected to a reference voltage, and the other electrode connected to the first node;

a first switching transistor including a gate electrode applied with a compensation control signal, one electrode connected to the first node, and the other electrode connected to a second node;

a first light emitting transistor including a gate electrode applied with a light emitting signal, one electrode connected to a first power source voltage, and the other electrode connected to the second node;

a driving transistor including a gate electrode connected to a third node, one electrode connected to the second node, and the other electrode connected to a fourth node;

a compensation transistor including a gate electrode applied with the compensation control signal, one electrode connected to the third node, and the other electrode connected to the fourth node; and

a second capacitor including one electrode connected to the third node and the other electrode connected to the first power source voltage.

28. The pixel of claim 27, further comprising a second switching transistor including a gate electrode applied with the scan signal, one electrode connected to the data line, and the other electrode connected to one electrode of the first capacitor.

29. The pixel of claim 27, further comprising a second light emitting transistor including a gate electrode applied with the light emitting signal, one electrode connected to the fourth node, and the other electrode connected to the anode of an organic light emitting diode (OLED).

30. The pixel of claim 29, further comprising an initialization transistor transmitting an initialization voltage to the third node according to the initialization signal.

31. The pixel of claim 30, wherein the initialization transistor includes a gate electrode applied with the initialization signal, one electrode connected to the data line, and the other electrode connected to the third node.

32. The pixel of claim 31, further comprising a second initialization transistor including a gate electrode applied with the initialization signal, one electrode connected to the first power source voltage, and the other electrode connected to the second node.

33. The pixel of claim 30, wherein the initialization transistor includes a gate electrode applied with the initialization signal, one electrode connected to the initialization voltage, and the other electrode connected to the third node.

34. The pixel of claim 33, further comprising a second initialization transistor including a gate electrode applied with the initialization signal, one electrode connected to the first power source voltage, and the other electrode connected to the second node.