DRIVING APPARATUS OF DISPLAY DEVICE, DISPLAY DEVICE INCLUDING THE SAME, AND METHOD OF DRIVING DISPLAY DEVICE

• US 20080246779A1
• Filed: 12/10/2007
• Published: 10/09/2008
• Est. Priority Date: 04/03/2007
• Status: Active Grant

• Current Assignee: Postech Academy-Industry Foundation, Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Postech Academy-Industry Foundation, Samsung Electronics Co. Ltd.
• Inventors: PARK, Jae-Byung, PARK, Cheol-Woo, LEE, Il-Pyung, JANG, Ung-Jin, LEE, Sung-Gu, LEE, Min-Gu, KIM, Hak-Gyu
• Granted Patent: US 8,035,661 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G06T 5/009 Global, i.e. based on properties of the image as a whole applied in cameras using an electronic image sensor H04N23/80, H04N23/70
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 5/026 Control of mixing and/or overlay of colours in general G09G5/022 and G09G5/024 take precedence

Abstract

The driving apparatus of a display device calculates a slope using a minimum gray, a maximum gray, a gray average of frame data in a current frame, and a gray average of frame data in a previous frame, and corrects and outputs the input frame data according to the slope, using frame data of one frame. As a result, a gray range of the input image signal can be extended, thereby improving visibility. Further, in a case of a motion picture, even when a difference of a gray range of images of adjacent frames is large, an original image is not distorted due to extension of a gray range. Also, even when noise is included in the input image signal, a gray range can be extended after removing the noise.

Claims

1. A driving apparatus of a display device, the driving apparatus comprising:

a gray range calculation unit which calculates a minimum gray and a maximum gray of a current image signal, which is an image signal of a current frame, or a signal that filters the current image signal with a low band;

a conversion variable calculation unit which calculates a conversion variable based on the minimum gray, the maximum gray, a gray average of a current image signal, and a gray average of a previous image signal, which is an image signal of a previous frame; and

an output signal generator which generates an output image signal by converting the current image signal according to the conversion variable.

2. The driving apparatus of a display device of claim 1, wherein conversion is linear conversion that uses the conversion variable as a slope.

3. The driving apparatus of a display device of claim 2, wherein the slope changes according to a slope of the previous image signal.

4. The driving apparatus of a display device of claim 3, wherein the slope Sc is given by

5. The driving apparatus of a display device of claim 4, wherein the slope Sc has a value of about 1 to about 2.5.

6. The driving apparatus of a display device of claim 4, wherein the conversion is defined by D′

=(D−

Min)Sc+c, where D is a current image signal, D′

is an output image signal, and c is a constant.

7. The driving apparatus of a display device of claim 6, wherein the constant c is identical to the gray minimum value of the current frame Min.

8. The driving apparatus of a display device of claim 3, wherein the conversion variable calculation unit comprises:

an average gray calculation unit which calculates a gray average of an image signal;

a first memory which stores the gray average calculated by the average gray calculation unit;

an α

-value calculation unit which calculates an α

-value by dividing a difference between a gray average of the current image signal and a gray average of the previous frame by a maximum gray value that can be displayed;

a basic slope computation unit which computes a basic slope in which a maximum gray that can be displayed is divided by a difference between the maximum gray and the minimum gray;

a slope computation unit which computes the basic slope, a slope of the previous image signal, and a slope of the current image signal based on the α

-value; and

a second memory which stores a slope that is computed in the slope computation unit and provides a slope of the previous image signal to the slope computation unit.

9. The driving apparatus of a display device of claim 8, wherein the output signal generator comprises:

a frame memory which stores the current image signal; and

a data correction unit which generates the output image signal by linearly converting the current image signal that is received from the frame memory according to the slope that is received from the slope computation unit.

10. The driving apparatus of a display device of claim 9, wherein the gray range calculation unit comprises:

a low band filter which removes noise by filtering the current image signal with a low band; and

a minimum gray and maximum gray calculation unit which calculates the minimum gray and the maximum gray of the current image signal that passes through the low band filter.

11. The driving apparatus of a display device of claim 10, wherein the low band filter corrects a current image signal of each pixel by providing and adding a predetermined weight to a current image signal of a pixel adjacent to the current image signal of each pixel.

12. The driving apparatus of a display device of claim 1, wherein low band filtration comprises correcting a current image signal of each pixel in consideration of a current image signal of adjacent pixels.

13. A method of driving a display device, the method comprising:

calculating a minimum gray and a maximum gray of a current image signal, which is an image signal of a current frame;

calculating a gray average of the current image signal;

calculating a slope based on the minimum gray, the maximum gray, the gray average of a current image signal, and a gray average of a previous image signal, which is an image signal of a previous frame; and

linearly converting the current image signal based on the slope.

14. The method of claim 13, wherein calculating the slope comprises:

calculating an α

-value in which a difference between the gray average of the current image signal and the gray average of the previous image signal is divided by a maximum gray value that can be displayed;

computing a basic slope in which the maximum gray value is divided by a difference between the maximum gray and the minimum gray; and

calculating the slope based on the α

-value, the basic slope, and a slope of the previous image signal.

15. The method of claim 14, wherein the slope Sc is given by Sc=1−

α

×

Sp+α

×

Sb, where Sp is the slope of the previous image signal and Sb is the basic slope.

16. The method of claim 15, wherein linearly converting satisfies D′

=(D−

min)Sc+c, where D is the current image signal, D′

is an output image signal, min is the minimum gray, and c is a constant.

17. The method of claim 16, wherein the constant c is identical to the minimum gray min.

18. The method of claim 13, further comprising removing noise existing in the current image signal before calculating the minimum gray and the maximum gray.

19. The method of claim 18, wherein removing noise comprises removing noise of each current image signal by providing and adding a weight to an image signal adjacent to the each current image signal.

20. A display device comprising:

a signal controller which generates an output image signal by correcting a current image signal, which is an image signal of a current frame, based on a gray average, a minimum gray, and a maximum gray of the current image signal, and a gray average of a previous image signal, which is an image signal of a previous frame;

a data driver which converts the output image signal to a data voltage; and

a display panel which receives the data voltage to display an image.

21. The display device of claim 20, wherein the signal controller linearly converts the current image signal to the output image signal based on a slope Sc that is calculated based on the minimum gray, the maximum gray, the gray average of the current image signal, and the gray average of the previous image signal.

22. The display device of claim 21, wherein the slope Sc changes according to a slope of the previous image signal.

23. The display device of claim 22, wherein the slope Sc is given by

24. The display device of claim 23, wherein conversion is defined by D′

=(D−

min)Sc+min, where D is the current image signal and D′

is the output image signal.