Electro-luminescence display device and method of driving the same

• US 7,538,749 B2
• Filed: 12/28/2004
• Issued: 05/26/2009
• Est. Priority Date: 04/29/2004
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Chung, Hoon Ju, Jeon, Chang Hoon
• Primary Examiner(s): Nguyen; Kevin M
• Application Number:
  US11/022,826
• Publication Number:
  US 20050243077A1
• Time in Patent Office: 1,610 Days
• Field of Search: 345/76, 345/77, 345/78, 345/82, 345/83, 345/102, 345/204, 315/169.1, 315/169.3
• US Class Current: 345/77
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• 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 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2029 the sub-frames having non-binary weights
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: 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

Abstract

An electro-luminescence display device and a method of driving the same for controlling a full white brightness depending upon a brightness of the external environment and thus controlling a brightness mode is disclosed. An electro-luminescence display device according to the present invention comprising: a display panel having pixels light-emitted by a supplied current; a data driver for applying a data voltage corresponding to said current to the pixels; and a timing controller for dividing one frame into a plurality of sub-frames and applying said data voltage corresponding to each of the plurality of sub-frames to the data driver and for controlling an emission time of each frame.

Claims

1. An electro-luminescence display device, comprising:

a display panel having pixels light-emitted by a supplied current;

a data driver for applying a data voltage corresponding to said current to the pixels;

a timing controller for dividing one frame into a plurality of sub-frames and applying a digital data corresponding to each of the plurality of sub-frames to the data driver and for controlling an emission time of each frame; and

a photo sensor for detecting a brightness of the external environment of the display panel,

wherein the timing controller modulates the digital data to be applied to the data driver in response to a brightness signal from the photo sensor,

wherein the timing controller comprises;

a selection signal generator for generating a selection signal in response to a brightness signal detected from the photo sensor;

a first data converter for converting N-bit data (wherein N is an integer) inputted from the exterior thereof into a first M-bit data (wherein M is an integer larger than N) to be applied to the data driver;

a second data converter for converting said N-bit data inputted from the exterior thereof into a second M-bit data to be applied to the data driver, wherein a number of gray levels of the second M-bit data are less than that of the first M bit data; and

a selector for selectively applying said N-bit data to any one of the first and second converters in response to said selection signal.

2. The electro-luminescence display device according to claim 1, wherein the timing controller controls the number of sub-frames depending upon at least one of brightness of an external environment of the display panel and a selection of a user.

3. The electro-luminescence display device according to claim 1, wherein each of the pixels includes a pixel of a digital driving system in which a digital data signal is supplied.

4. The electro-luminescence display device according to claim 3, wherein each of the pixels includes:

a data line supplied with said data voltage;

a display gate line supplied with a gate pulse;

a non-display gate line supplied with an erasure pulse;

a light-emitting cell connected between a supply voltage source and a ground voltage source;

a driving switch connected between the supply voltage source and the light-emitting cell;

a first switching device connected to the data line, the display gate line and the driving switch;

a second switching device connected to a first node positioned between the driving switch and the first switching device, the non-display gate line and the supply voltage source; and

a storage capacitor connected between the first node and the supply voltage source.

5. The electro-luminescence display device according to claim 1, wherein the

second converter sets (M-K) bits (wherein k is an integer smaller than M) of said N bits to a value of ‘

0’

.

6. The electro-luminescence display device according to claim 5, wherein the selection signal generator generates a first logical state of selection signal when said brightness of the external environment of the display panel is relatively high while generating a second logical state of selection signal when said brightness of the external environment of the display panel is relatively low.

7. The electro-luminescence display device according to claim 6, wherein the selection signal generator applies said N-bit data to the first data converter in response to said first logical state of selection signal while applying said N-bit data to the second data converter in response to said second logical state of selection signal.

8. The electro-luminescence display device according to claim 5, wherein each of the first and second data converters converts said N-bit data into said M-bit data in such a manner to have any one of a binary code and a non-binary code.

9. The electro-luminescence display device according to claim 8, wherein a gray level value corresponding to said M-bit data converted by the first data converter is larger than a gray level value corresponding to said M-bit data converted by the second data converter.

10. The electro-luminescence display device according to claim 5, wherein each of the plurality of sub-frames has a light-emission time corresponding to each bit of said M-bit data.

11. The electro-luminescence display device according to claim 5, wherein the second data converter converts said N-bit data into a data having less than K bits, and sets (M-K) bits of M most significant bits to a value of ‘

0’

.

12. The electro-luminescence display device according to claim 5, wherein M is 12 and N is 6.

13. The electro-luminescence display device according to claim 1, wherein the timing controller divides one frame into a plurality of sub-frames having the emission time and a non-emission time and controls the emission time of each of the sub-frames.

14. The electro-luminescence display device according to claim 13, wherein each of the pixels includes a pixel of a digital driving system in which a digital data signal is supplied.

15. The electro-luminescence display device according to claim 14, wherein each of the pixels includes:

a data line supplied with said data voltage;

a display gate line supplied with a gate pulse;

a non-display gate line supplied with an erasure pulse;

a light-emitting cell connected between a supply voltage source and a ground voltage source;

a driving switch connected between the supply voltage source and the light-emitting cell;

a first switching device connected to the data line, the display gate line and the driving switch;

a second switching device connected to a first node positioned between the driving switch and the first switching device, the non-display gate line and the supply voltage source; and

a storage capacitor connected between the first node and the supply voltage source.

16. The electro-luminescence display device according to claim 15, further comprising:

a gate driver for sequentially applying said gate pulse to the display gate lines and for sequentially applying said erasure pulse to the non-display gate lines.

17. The electro-luminescence display device according to claim 16, wherein the timing controller includes:

a selection signal generator for generating a selection signal in response to a brightness signal detected from the photo sensor;

a data converter for converting N-bit data (wherein N is an integer) inputted from the exterior thereof into M-bit data (wherein M is an integer larger than N); and

a control signal generator for applying a gate control signal for reducing said emission time to the gate driver in response to said selection signal.

18. The electro-luminescence display device according to claim 17, wherein the selection signal generator generates a first logical state of selection signal when said brightness of the external environment of the display panel is relatively high while generating a second logical state of selection signal when said brightness of the external environment of the display panel is relatively low.

19. The electro-luminescence display device according to claim 18, wherein the control signal generator applies a first gate signal for allowing an emission time of each of the plurality of sub-frames to correspond to each bit of said M-bit data to the gate driver in response to said first logical state of selection signal, and applies a second gate control signal for allowing said emission time of each of the plurality of sub-frames corresponding to each bit of said M-bit data to be reduced to the gate driver in response to said second logical state of selection signal.

20. The electro-luminescence display device according to claim 19, wherein the gate driver applies said erasure pulse to the non-display gate lines such that said emission time of each of the plurality of sub-frames corresponds to each bit of said N-bit data, after applying said gate pulse to the display gate lines on a basis of said first gate signal.

21. The electro-luminescence display device according to claim 19, wherein the gate driver applies said erasure pulse to the non-display gate lines such that said emission time of each of the plurality of sub-frames is reduced, after applying said gate pulse to the display gate lines on a basis of said second gate signal.

22. The electro-luminescence display device according to claim 21, wherein each of said emission time reduced at each of the plurality of sub-frames is reduced at a ratio of J (wherein J is an integer) with respect to each emission time of each of the plurality of sub-frames corresponding to each bit of said M-bit data.

23. The electro-luminescence display device according to claim 17, wherein the data converter converts said N-bit data into said M-bit data in such a manner to have any one of a binary code and a non-binary code.

24. A method of driving an electro-luminescence display device including a display panel having pixels light-emitted by a supplied current and a data driver for applying a data voltage corresponding to said current to the pixels comprising steps of:

dividing one frame into a plurality of sub-frames;

generating a selection signal in response to a brightness signal detected from a photo sensor;

converting N-bit data (wherein N is an integer) inputted from the exterior thereof into a first M-bit data (wherein M is an integer larger than N) to be applied to the data driver, according to a first logic of the selection signal;

converting said N-bit data inputted from the exterior thereof into a second M-bit data to be applied to the data driver, wherein a number of gray levels of the second M-bit data are less than that of the first M bit data, according to a second logic of the selection signal;

applying the first and second M bit data corresponding to each of the plurality of sub-frames to the data driver; and

controlling an emission time of each frame.

25. The method according to claim 24, wherein the step of controlling an emission time of each frame includes controlling the number of the sub-frames included in each frame.

26. The method according to claim 25, wherein the step of controlling an emission time of each frame includes controlling the number of sub-frames included in each frame depending upon at least one of brightness of an external environment of the display panel and a selection of a user.

27. The method according to claim 24, wherein the step of controlling an emission time of each frame includes dividing one frame into a plurality of sub-frames having the emission time and a non-emission time and controlling the emission time of each of the sub-frames.