Display device

Abstract

A display device includes a first substrate, a second substrate, and a first photocoupler. The first photocoupler includes a first-color liquid crystal grating, a second-color liquid crystal grating, and a third-color liquid crystal grating. The collimated projections of the first-color liquid crystal grating, the second-color liquid crystal grating, and the third-color liquid crystal grating on the first substrate overlap. Two of the first-color liquid crystal grating, the second-color liquid crystal grating, and the third-color liquid crystal grating are disposed on one of the first substrate and the second substrate, and the third-color liquid crystal grating is disposed on the other of the first substrate and the second substrate.

Claims

1. A display device, comprising: The first substrate has a first surface and a second surface; The second substrate has a third surface and a fourth surface, wherein the third surface faces the second surface; The first optical coupling element includes a first-color liquid crystal grating, a second-color liquid crystal grating, and a third-color liquid crystal grating, wherein the collimated projections of the first-color liquid crystal grating, the second-color liquid crystal grating, and the third-color liquid crystal grating on the first substrate overlap, and wherein two of the first-color liquid crystal grating, the second-color liquid crystal grating, and the third-color liquid crystal grating are disposed on one of the second surface and the fourth surface, and the other of the first-color liquid crystal grating, the second-color liquid crystal grating, and the third-color liquid crystal grating are disposed on the other of the second surface and the fourth surface.

2. The display device as claimed in claim 1, wherein the first color liquid crystal grating, the second color liquid crystal grating, and the third color liquid crystal grating are liquid crystal block gratings.

3. The display device as claimed in claim 2, wherein the first color liquid crystal grating, the second color liquid crystal grating, and the third color liquid crystal grating comprise a plurality of liquid crystal molecules, each liquid crystal molecule having a tilt angle in the range of 24° to 31.5°, and the tilt angles of the first color liquid crystal grating, the second color liquid crystal grating, and the third color liquid crystal grating are different from each other.

4. The display device as claimed in claim 2, wherein one of the first color liquid crystal grating, the second color liquid crystal grating, and the third color liquid crystal grating is a blue liquid crystal block grating, wherein when collimated blue light is incident on the blue liquid crystal block grating, the diffraction efficiency DE of the collimated blue light satisfies the condition DE=A+B*cos(x*d)+C*sin(x*d)+E*cos(2x*d)+F*sin(2x*d), where d is the thickness of the blue liquid crystal block grating, and the coefficients A, B, C, E, F, and x of the condition are 0.7209, 0.119, -0.06737, 0.04909, 0.1381, and 0.004807, respectively.

5. The display device as claimed in claim 2, wherein one of the first color liquid crystal grating, the second color liquid crystal grating, and the third color liquid crystal grating is a green liquid crystal block grating, wherein when collimated green light is incident on the green liquid crystal block grating, the diffraction efficiency DE of the collimated green light satisfies the condition DE=A+B*cos(x*d)+C*sin(x*d)+E*cos(2x*d)+F*sin(2x*d), where d is the thickness of the green liquid crystal block grating, and the coefficients A, B, C, E, F, and x of the condition are 0.4958, 0.1482, -0.04764, -0.00472, 0.09313, and 0.003966, respectively.

6. The display device as claimed in claim 2, wherein one of the first color liquid crystal grating, the second color liquid crystal grating, and the third color liquid crystal grating is a red liquid crystal block grating, wherein when collimated red light is incident on the red liquid crystal block grating, the diffraction efficiency DE of the collimated red light satisfies the condition DE=A+B*cos(x*d)+C*sin(x*d)+E*cos(2x*d)+F*sin(2x*d), where d is the thickness of the red liquid crystal block grating, and the coefficients A, B, C, E, F, and x of the condition are 0.4643, 0.03547, -0.1531, 0.06593, 0.02541, and 0.003276, respectively.

7. The display device as claimed in claim 2, wherein the thickness of any one of the first color liquid crystal grating, the second color liquid crystal grating, and the third color liquid crystal grating falls within the range of 500 nm to 1500 nm.

8. The display device as claimed in claim 1, wherein any one of the first color liquid crystal grating, the second color liquid crystal grating, and the third color liquid crystal grating is a reflective diffraction grating.

9. The display device as claimed in claim 1 further includes a second optical coupling element and a third optical coupling element, wherein the first optical coupling element is an input coupler, the second optical coupling element is a deflector, and the third optical coupling element is an output coupler.

10. The display device of claim 9, wherein the second optical coupling element includes a first liquid crystal grating and a second liquid crystal grating, the third optical coupling element includes a third liquid crystal grating and a fourth liquid crystal grating, the first liquid crystal grating and the third liquid crystal grating are disposed on the second surface, and the second liquid crystal grating and the fourth liquid crystal grating are disposed on the fourth surface.

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