Flexible display device and method of driving the flexible display device

1. A flexible display device comprising:

a flexible display panel having a first display area that is adjacent to a first end of the flexible display panel and a second display area that is adjacent to a second end of the flexible display panel;

a data driver configured to output a data voltage to the flexible display panel; and

a driving controller configured to control the data driver, the driving controller including a YCbCr converter configured to convert input RGB data included in input image data into input YCbCr data, and an image processor 220 configured to receive the input YCbCr data and to compensate for a luminance and a color difference of the input YCbCr data to generate output YCbCr data for displaying the second image in the second display area that compensates for the first image;

wherein a second image displayed in the second display area is a compensation image that compensates for a luminance and a color difference of the first image displayed in the first display area, and

wherein the image processor is further configured to:

calculate a first effective constant and a second effective constant based on input luminance data included in the input YCbCr data;

calculate a first luminance parameter and a second luminance parameter by using a look-up table for defining a relation between the first effective constant and the first luminance parameter and a relation between the first effective constant and the second luminance parameter;

calculate a luminance compensation parameter based on the first luminance parameter and the second luminance parameter; and

calculate output luminance data based on the luminance compensation parameter and a luminance weight.

2. The flexible display device of claim 1 , wherein the first image displayed in the first display area compensates for the second image displayed in the second display area.

3. The flexible display device of claim 1 , wherein, in a first mode, the first image displayed in the first display area and the second image displayed in the second display area form one continuous image,

wherein, in a second mode, the first image displayed in the first display area and the second image displayed in the second display area are substantially symmetrical to each other with respect to a folding line of the flexible display panel, and

wherein, in the second mode, the second image displayed in the second display area is the compensation image that compensates for the luminance and the color difference of the first image displayed in the first display area.

4. The flexible display device of claim 3 , wherein the second image displayed in the second display area is the compensation image having one-to-one correspondence with the first image displayed in the first display area in a unit of a pixel.

5. The flexible display device of claim 3 , wherein the flexible display panel is configured to display the compensation image in the second display area when a folding angle between the first display area and the second display area is less than 90 degrees.

6. The flexible display device of claim 1 , wherein the driving controller further comprises:

an RGB converter configured to convert the output YCbCr data into a data signal including output RGB data.

7. The flexible display device of claim 1 , wherein the image processor is configured to:

calculate the first effective constant by using a mathematical formula “q=rounddown(Y_IN/32)”, wherein q is the first effective constant, Y_IN is the input luminance data, and rounddown(Y_IN/32) is an integer part of a value obtained by dividing the input luminance data by 32; and

calculate the second effective constant by using a mathematical formula “r=mod(Y_IN,32)”, wherein r is the second effective constant, and mod(Y_IN,32) is a remainder of a value obtained by dividing the input luminance data by 32.

8. The flexible display device of claim 1 , wherein the image processor is configured to: calculate the first luminance parameter by using a mathematical formula “cf1=LUT(q)*32” and calculate the second luminance parameter by using a mathematical formula “cf2=LUT(q+1)*32” when the first effective constant is less than a reference effective constant, wherein cf1 is the first luminance parameter, cf2 is the second luminance parameter, LUT(q) is a corresponding value corresponding to the first effective constant defined in the look-up table, and LUT(q+1) is a corresponding value corresponding to qt+1 defined in the look-up table; and calculate the first luminance parameter by using a mathematical formula “cf1=LUT(q)*32” and calculate the second luminance parameter by using a mathematical formula “cf2=LUT(q)*32” when the first effective constant is greater than or equal to the reference effective constant, wherein cf1 is the first luminance parameter, cf2 is the second luminance parameter, and LUT(q) is a corresponding value corresponding to the first effective constant defined in the look-up table.

9. The flexible display device of claim 1 , wherein the image processor is configured to:

calculate the luminance compensation parameter by using a mathematical formula “cf=rounddown((cf2−cf1)*r/32)+cf1” when the first luminance parameter is less than or equal to the second luminance parameter, wherein cf is the luminance compensation parameter, cf1 is the first luminance parameter, cf2 is the second luminance parameter, r is the second effective constant, and rounddown((cf2−cf1)*r/32) is an integer part of (cf2−cf1)*r/32; and

calculate the luminance compensation parameter by using a mathematical formula “cf=cf1−rounddown((cf1−cf2)*r/32)” when the first luminance parameter is greater than the second luminance parameter, wherein cf is the luminance compensation parameter, cf1 is the first luminance parameter, cf2 is the second luminance parameter, r is the second effective constant, and rounddown((cf1−cf2)*r/32) is an integer part of (cf1−cf2)*r/32.

10. The flexible display device of claim 1 , wherein the image processor is configured to calculate the output luminance data by using a mathematical formula “Y_OUT=Y_IN+cf*LW”, wherein Y_OUT is the output luminance data, Y_IN is the input luminance data, cf is the luminance compensation parameter, and LW is the luminance weight.

11. The flexible display device of claim 6 , wherein the image processor is configured to receive a color difference setting value and to calculate a color difference adjustment value and a threshold color difference adjustment weight based on the color difference setting value,

wherein the color difference setting value includes at least one of color difference control values, an input color difference weight, reference color difference weights, and input threshold color difference adjustment weights, and

wherein the image processor is configured to:

calculate the color difference adjustment value by using a mathematical formula “Interpolation_point=(reg_color_ctrl1-reg_color_ctrl0)*reg_color_weight/64+reg_color_ctrl0” and calculate the threshold color difference adjustment weight by using a mathematical formula “color_weight_th_i=reg_color_weight_th_i1” when the input color difference weight is less than or equal to a first reference color difference weight, wherein Interpolation_point is the color difference adjustment value, reg_color_ctrl0 is an initial color difference control value, reg_color_ctrl1 is a first color difference control value, reg_color_weight is an input color difference weight, color_weight_th_i is the threshold color difference adjustment weight, and reg_color_weight_th_i1 is a first input threshold color difference adjustment weight;

calculate the color difference adjustment value by using a mathematical formula “Interpolation_point=(reg_color_ctrl2-reg_color_ctrl1)*(reg_color_weight-w1)/64+reg_color_ctrl1” and calculate the threshold color difference adjustment weight by using a mathematical formula “color_weight_th_i=reg_color_weight_th_i2” when the input color difference weight is greater than the first reference color difference weight and less than or equal to a second reference color difference weight, wherein Interpolation_point is the color difference adjustment value, reg_color_ctrl1 is the first color difference control value, reg_color_ctrl2 is a second color difference control value, reg_color_weight is the input color difference weight, color_weight_th_i is the threshold color difference adjustment weight, and reg_color_weight_th_i2 is a second input threshold color difference adjustment weight;

calculate the color difference adjustment value by using a mathematical formula “Interpolation_point=(reg_color_ctrl3−reg_color_ctrl2)*(reg_color_weight-w2)/64+reg_color_ctrl2” and calculate the threshold color difference adjustment weight by using a mathematical formula “color_weight_th_i=reg_color_weight_th_i3” when the input color difference weight is greater than the second reference color difference weight and less than or equal to a third reference color difference weight, wherein Interpolation_point is the color difference adjustment value, reg_color_ctrl2 is the second color difference control value, reg_color_ctrl3 is a third color difference control value, reg_color_weight is the input color difference weight, color_weight_th_i is the threshold color difference adjustment weight, and reg_color_weight_th_i3 is a third input threshold color difference adjustment weight; and

calculate the color difference adjustment value by using a mathematical formula “Interpolation_point=(reg_color_ctrl4-reg_color_ctrl3)*(reg_color_weight-w3)/64+reg_color_ctrl3” and calculate the threshold color difference adjustment weight by using a mathematical formula “color_weight_th_i=reg_color_weight_th_i4” when the input color difference weight is greater than the third reference color difference weight and less than or equal to a fourth reference color difference weight, wherein Interpolation_point is the color difference adjustment value, reg_color_ctrl3 is the third color difference control value, reg_color_ctrl4 is a fourth color difference control value, reg_color_weight is the input color difference weight, color_weight_th_i is the threshold color difference adjustment weight, and reg_color_weight_th_i4 is a fourth input threshold color difference adjustment weight.

12. The flexible display device of claim 6 , wherein the image processor is configured to:

receive a color difference setting value and calculate a color difference adjustment value and a threshold color difference adjustment weight based on the color difference setting value;

calculate a Cb color difference compensation parameter based on input Cb color difference data included in the input YCbCr data, the color difference adjustment value, and an input threshold color difference weight included in the color difference setting value;

calculate effective Cb color difference data by using a mathematical formula “Cb_V=Cb_IN−MP”, wherein Cb_V is the effective Cb color difference data, Cb_IN is the input Cb color difference data, and MP is color difference middle data;

perform bit-conversion on the input threshold color difference weight to calculate a threshold color difference weight; and

calculate output Cb color difference data based on the effective Cb color difference data and the Cb color difference compensation parameter.

13. The flexible display device of claim 12 , wherein the image processor is configured to:

calculate the Cb color difference compensation parameter by using a mathematical formula “cb_interpolation_point=2{circumflex over ( )}28+interpolation_point*2{circumflex over ( )}20-interpolation_point*(abs(Cb_V)−color_weight_th)*color_weight_th_i” when an absolute value of the effective Cb color difference data is greater than the threshold color difference weight, wherein cb_interpolation_point is the Cb color difference compensation parameter, interpolation_point is the color difference adjustment value, abs(Cb_V) is the absolute value of the effective Cb color difference data, color_weight_th is the threshold color difference weight, and color_weight_th_i is the threshold color difference adjustment weight; and

calculate the Cb color difference compensation parameter by using a mathematical formula “cbinterpolation_point=2{circumflex over ( )}28+interpolation_point*2{circumflex over ( )}20” when the absolute value of the effective Cb color difference data is less than or equal to the threshold color difference weight, wherein cb_interpolation_point is the Cb color difference compensation parameter, and interpolation_point is the color difference adjustment value.

14. The flexible display device of claim 12 , wherein the image processor is configured to:

calculate middle Cb color difference data by using a mathematical formula “Cb_MIDDLE=Cb_V*(cb_interpolation_point)/2{circumflex over ( )}28”, wherein Cb_MIDDLE is the middle Cb color difference data, Cb_V is the effective Cb color difference data, and cb_interpolation_point is the Cb color difference compensation parameter; and

calculate the output Cb color difference data by using a mathematical formula “Cb_OUT=Cb_MIDDLE+MP”, wherein Cb_OUT is the output Cb color difference data, Cb_MIDDLE is the middle Cb color difference data, and MP is the color difference middle data.

15. The flexible display device of claim 6 , wherein the image processor is configured to:

calculate a Cr color difference compensation parameter based on input Cr color difference data included in the input YCbCr data, a color difference adjustment value calculated based on a color difference setting value, and an input threshold color difference weight included in the color difference setting value;

calculate effective Cr color difference data by using a mathematical formula “Cr_V=Cr_IN−MP”, wherein Cr_V is the effective Cr color difference data, Cr_IN is the input Cr color difference data, and MP is color difference middle data;

perform bit-conversion on the input threshold color difference weight to calculate a threshold color difference weight; and

calculate output Cr color difference data based on the effective Cr color difference data and the Cr color difference compensation parameter.

16. The flexible display device of claim 15 , wherein the image processor is configured to:

calculate the Cr color difference compensation parameter by using a mathematical formula “cr_interpolation_point=2{circumflex over ( )}28+interpolation_point*2{circumflex over ( )}20-interpolation_point*(abs(Cr_V)−color_weight_th)*color_weight_th_i” when an absolute value of the effective Cr color difference data is greater than the threshold color difference weight, wherein cr_interpolation_point is the Cr color difference compensation parameter, interpolation_point is the color difference adjustment value, abs(Cr_V) is the absolute value of the effective Cr color difference data, color_weight_th is the threshold color difference weight, and color_weight_th_i is the threshold color difference adjustment weight; and

calculate the Cr color difference compensation parameter by using a mathematical formula “cr_interpolation_point=2{circumflex over ( )}28+interpolation_point*2{circumflex over ( )}20” when the absolute value of the effective Cr color difference data is less than or equal to the threshold color difference weight, wherein cr_interpolation_point is the Cr color difference compensation parameter, and interpolation_point is the color difference adjustment value.

17. The flexible display device of claim 15 , wherein the image processor is configured to:

calculate middle Cr color difference data by using a mathematical formula “Cr_MIDDLE=Cr_V*(cr_interpolation_point)/2{circumflex over ( )}28”, wherein Cr_MIDDLE is the middle Cr color difference data, Cr_V is the effective Cr color difference data, and cr_interpolation_point is the Cr color difference compensation parameter; and

calculate the output Cr color difference data by using a mathematical formula “Cr_OUT=Cr_MIDDLE+MP”, wherein CLOUT is the output Cr color difference data, Cr_MIDDLE is the middle Cr color difference data, and MP is the color difference middle data.

18. A method of driving a flexible display device, the method comprising the steps of:

displaying a first image in a first display area that is adjacent to a first end of a flexible display panel;

displaying a second image in a second display area that is adjacent to a second end of the flexible display panel,

converting input RGB data included in input image data into input YCbCr data;

calculating a first effective constant and a second effective constant based on input luminance data included in the input YCbCr data;

calculating a first luminance parameter and a second luminance parameter by using a look-up table for defining a relation between the first effective constant and the first luminance parameter and a relation between the first effective constant and the second luminance parameter;

calculating a luminance compensation parameter based on the first luminance parameter and the second luminance parameter; and

calculating output luminance data based on the luminance compensation parameter and a luminance weight,

wherein, in a first mode, the first image displayed in the first display area and the second image displayed in the second display area form one continuous image,

wherein, in a second mode, the first image displayed in the first display area and the second image displayed in the second display area are substantially symmetrical to each other with respect to a folding line of the flexible display panel, and

wherein, in the second mode, the second image displayed in the second display area compensates for a luminance and a color difference of the first image displayed in the first display area.

19. The method of claim 18 , further comprising the steps of:

compensating for a luminance and a color difference of the input YCbCr data to generate output YCbCr data for displaying the second image in the second display area that compensates for the luminance and the color difference of the first image; and

converting the output YCbCr data into a data signal including output RGB data.