Display device

1. A display device comprising:

a first substrate including a pixel circuit;

a second substrate disposed opposite to the first substrate;

an optical element layer including liquid crystal material and disposed between the first substrate and the second substrate;

a polarizer disposed between the second substrate and the optical element layer;

an alignment film contacting the liquid crystal material and disposed on the second substrate; and

a polyimide layer between the alignment film and the second substrate;

wherein the second substrate has strength greater than that of the first substrate, and

an outer surface of the second substrate is an outermost surface of the display device on a viewing side of the display device.

2. The display device of claim 1 , wherein the first substrate is an alkali-free glass substrate, and the second substrate is an alkali glass substrate or a sapphire substrate.

3. The display device of claim 1 , wherein the first substrate has a thickness of less than 0.3 mm, and the second substrate has a thickness of 0.3 mm or more.

4. The display device of claim 1 , wherein the polyimide layer is disposed between the polarizer and the optical element layer.

5. The display device of claim 4 , wherein the polyimide layer has a thickness of 0.5 to 20 μm.

6. The display device of claim 4 , wherein an inorganic layer is disposed between the polyimide layer and the optical element layer.

7. The display device of claim 4 , wherein the polyimide layer includes a first organic layer and a second organic layer, and the first organic layer is disposed closer to the second substrate than the second organic layer.

8. The display device of claim 1 , wherein a detection electrode is disposed between the second substrate and the polarizer.

9. The display device of claim 1 , wherein the first substrate and the second substrate do not include any other substrate therebetween.

10. The display device of claim 1 , further comprising:

a detection electrode between the second substrate and the polyimide layer.

11. A display device comprising:

a first substrate including a pixel circuit;

a second substrate disposed opposite to the first substrate;

an optical element layer disposed between the first substrate and the second substrate;

a polarizer disposed between the second substrate and the optical element layer;

a polyimide layer between the optical element layer and the second substrate; and

a detection electrode between the second substrate and the polyimide layer,

wherein the second substrate has strength greater than that of the first substrate, and

an outer surface of the second substrate is an outermost surface of the display device on a viewing side of the display device.

12. The display device of claim 11 , wherein the first substrate is an alkali-free glass substrate, and the second substrate is an alkali glass substrate or a sapphire substrate.

13. The display device of claim 11 , wherein the first substrate has a thickness of less than 0.3 mm, and the second substrate has a thickness of 0.3 mm or more.

14. The display device of claim 11 , wherein the polyimide layer is disposed between the polarizer and the optical element layer.

15. The display device of claim 11 , wherein an inorganic layer is disposed between the polyimide layer and the optical element layer.

16. The display device of claim 15 , wherein the inorganic layer has a thickness of 0.1 to 5 μm.

17. The display device of claim 11 , wherein the polyimide layer includes a first organic layer and a second organic layer, and the first organic layer is disposed closer to the second substrate than the second organic layer.

18. The display device of claim 11 , wherein a detection electrode is disposed between the second substrate and the polarizer.

19. The display device of claim 11 , wherein the first substrate and the second substrate do not include any other substrate therebetween.