Color signal generating device

1. A color signal generating device for converting signals from a first color signal for forming a number of input pixels representing a combination of colors to be displayed on a position of each pixel of a display device to a second color signal for forming a number of output pixels driving the display device, comprising:

storage for storing information of a combination of colors of sub-pixels included in said each pixel of the display device,

a detector circuit for detecting a difference of signal values of colors of the first color signal, displayed on two adjacent pixels which are adjacent across a reference pixel,

wherein a first one of the adjacent pixel has a higher signal value and a second one of the adjacent pixel has a lower signal value, and

a distributor circuit for distributing a signal value of a color for the reference pixel,

wherein the combination of the colors of the sub-pixels of the reference pixel does not have a first color of the first color signal,

wherein said first color is in the combination of the colors of the sub-pixels of each of the two adjacent pixels and is displayed on the two adjacent pixels using the second color signal,

wherein a value added to said higher signal value of the first one of the adjacent pixels is more than a value added to said lower signal value of the second one of the adjacent pixels; and

wherein the value added to the higher signal value of the first one of the adjacent pixels and the value added to said lower signal value of the second one of the adjacent pixels add up to total a signal value of the reference pixel.

2. The color signal generating device according to claim 1 , comprising a memory means for storing image data having said number of input pixels the first color signal.

3. The color signal generating device according to claim 1 ,

wherein said combination of colors represented by said first color signal is a color signal having three colors: includes red, green and blue, and

said second color signal is a color signal having four colors: said combination of colors of said sub-pixels is one or two colors selected from red, green, and blue and achromatic color.

4. The color signal generating device according to claim 1 ,

further comprising an adding circuit for adding a signal value of a signal value of said color which the combination of the colors of the sub-pixels does not have in the reference pixel in the first color signal to a signal value of a color which is different from said color which the combination of the colors of the sub-pixels does not have, and is displayed on said reference pixel of said second color signal.

5. The color signal generating device according to claim 1 ,

wherein said color which the combination of the colors of the sub-pixels does not have, and is displayed on said reference pixel is an achromatic color.

6. The color signal generating device according to claim 1 ,

wherein said combination of colors represented by said first color signal is a color signal consisting of red, green and blue, and wherein said second color signal is a color signal that has a first color, a second color, a third color and a fourth color, wherein said combination of colors of the sub-pixels comprises one or two colors selected from the group consisting of red, green, blue and an achromatic color.

7. The color signal generating device according to claim 1 ,

wherein the increases signal value for pixels Xi and Xk which are adjacent to reference pixel Xj, is set by the distributor circuit according to the following formula:

Xi*=Xi+Xj×Di

Xk*=Xk+Xj×Dk

wherein color signals Xi and Xk are for pixels Xi and Xk respectively, which are adjacent to reference pixel Xj, and Di and Dk are distribution coefficients, and Xi* and Xk* are the calculated signal value for pixels Xi and Xk.

8. The color signal generating device according to claim 1 , wherein a gradient of signal value is calculated for said adjacent pixels.

9. The color signal generating device according to claim 8 ,

wherein according to the gradient of signal value, a distribution ratio is calculated for determining a ratio of signal value to add to each of said adjacent pixels.

10. A display device comprising:

the color signal generating device according to claim 1 , a liquid crystal display panel,

and a backlight.

11. A color signal generating device comprising:

storage for storing information of a combination of colors of sub-pixels included in each pixel of a display device,

a detector circuit for detecting a difference of signal values of colors of a first color signal, displayed on two adjacent pixels, a first pixel and a second pixel, which are adjacent across a reference pixel,

wherein the first pixel has a higher signal value and the second pixel has a lower signal value,

a distributor circuit for distributing a signal value of a color for the reference pixel to the first and second pixels,

wherein the combination of the colors of the sub-pixels of the reference pixel does not have a first color of the first color signal,

wherein said first color is in the combination of the colors of the sub-pixels of each of the first and second pixels and is displayed on the first and second pixels using a second color signal,

wherein a value added to said first pixels is more than a value added to said second pixel, and

wherein the value added to said first pixel and the value added to said second pixel combines to equal a signal value of said reference pixel.