Liquid crystal display device displaying a color mixing light and method for driving the same

1. A display device displaying a color by mixing light reflected by a first liquid crystal region and light reflected by a second liquid crystal region by additive color mixture, in which

a dominant wavelength of the light reflected by the first liquid crystal region is in one of a range of 450-500 nm and a range of 570-640 nm,

a dominant wavelength of the light reflected by the second liquid crystal region is in the other of the range of 450-500 nm and the range of 570-640 nm,

the light reflected by the first liquid crystal region, and the light reflected by the second liquid crystal region have a substantially mutually complementary color relationship, and

a reflection band of the first liquid crystal region and the second liquid crystal region, which reflects light on a side of shorter wavelengths being narrower than a reflection band of the first liquid crystal region and the second liquid crystal region which reflects light on a side of longer wavelengths.

2. A display device according to claim 1 , wherein at least one of the first liquid crystal region and the second liquid crystal region is formed of a liquid crystal material having a cholesteric phase.

3. A display device according to claim 1 , wherein the reflection band of the liquid crystal region which reflects light on the side of the shorter wavelengths has a full width at half maximum value of not more than 70 nm.

4. A display device according to claim 1 , wherein at least one of the first liquid crystal region and the second liquid crystal region is micro-capsuled.

5. A display device according to claim 1 , further comprising a pair of electrodes for applying an electric field to the first liquid crystal region and the second liquid crystal region to change a display state of at least one of the first liquid crystal region and the second liquid crystal region.

6. A display device according to claim 1 , further comprising:

a first pair of electrodes for applying an electric field to the first liquid crystal region to change a display state of the first liquid crystal region; and

a second pair of electrodes for applying an electric field to the second liquid crystal region to change a display state of the second liquid crystal region.

7. A display device according to claim 1 , wherein a first threshold voltage for changing a display state of the first liquid crystal region and a second threshold voltage for changing a display state of the second liquid crystal region are substantially equal to each other.

8. A display device according to claim 1 , further comprising:

a photoconductive layer which generates charges by an application of light, and

wherein a threshold voltage difference occurs between a light applied region and a light non-applied region, which has been produced by the charges emitted from the photoconductive layer being used to selectively change a display state of the light applied region of the first liquid crystal region or the second liquid crystal region.

9. A display device according to claim 1 , further comprising a partition layer of glass for spacing the first liquid crystal region and the second liquid crystal region from each other.

10. A display device according to claim 1 , wherein the second liquid crystal region reflects a circularly polarized light which has a polarized direction opposite to a circularly polarized light reflected by the first liquid crystal region.

11. A display device according to claim 1 , further comprising a partition layer of a film sheet, for spacing the first liquid crystal region and the second liquid crystal region from each other.

12. A display device according to claim 11 , wherein:

the first liquid crystal region is disposed nearer an observation side than the second liquid crystal region;

the second liquid crystal region reflects a circularly polarized light which has the same polarized direction as a circularly polarized light reflected by the first liquid crystal region; and

a phase difference between an ordinary ray and an extraordinary ray passing through the partition layer and entering the second liquid crystal region is substantially equal to odd multiples of λ/2 when a selective reflection wavelength of the second liquid crystal region is λ.

13. A display device according to claim 11 , wherein:

the first liquid crystal region is disposed nearer an observation side than the second liquid crystal region;

the second liquid crystal region reflects a circularly polarized light which has a polarized direction opposite to a circularly polarized light reflected by the first liquid crystal region; and

a phase difference between an ordinary ray and an extraordinary ray passing through the partition layer and entering the second liquid crystal region is substantially equal to even multiples of λ/2 when a selective reflection wavelength of the second liquid crystal region is λ.

14. A display device according to claim 1 , further comprising:

a third liquid crystal region for reflecting light at a selective reflection wavelength which is substantially equal to that of the first liquid crystal region;

a fourth liquid crystal region for reflecting light at a selective reflection wavelength which is substantially equal to that of the second liquid crystal region; and

wherein the third liquid crystal region reflects a circularly polarized light which has a polarized direction opposite to a circularly polarized light reflected by the first liquid crystal region, and the fourth liquid crystal region reflects circularly polarized light which has a polarized direction opposite to a circularly polarized light reflected by the second liquid crystal region.

15. A display device according to claim 1 , wherein a reflection state of one of the first liquid crystal region and the second liquid crystal region is changed to display a chromatic color.

16. A display device according to claim 15 , wherein the chromatic color is blue or yellow.