Display device comprising multifunction glass, production method and optical element having a fresnel structure

1. A multifunction optical element for a display device, the display device comprising an image-generating module which generates an image, the multifunction optical element comprising:

a coupling-in area and a coupling-out area, the coupling-in area being located separately from the coupling-out area, wherein a structure of the multifunction optical element is such that the image generated by the image-generating module that is coupled into the multifunction optical element via the coupling-in area, is guided in the multifunction optical element along a folded optical path by multiple total internal reflections from the coupling-in area to the coupling-out area and coupled out via the coupling-out area such that a user can perceive a coupled-out image superimposed on surroundings;

wherein the coupling-out area comprises a Fresnel structure which receives light from the coupling-in area via the folded optical path and couples the image out of the multifunction optical element; and

wherein the coupling-out area has an imaging property because the coupling out area corresponds to an imaginary optically effective surface that is curved.

2. The multifunction optical element according to claim 1 , wherein the Fresnel structure is at least partially reflective.

3. The multifunction optical element according to claim 2 , wherein the Fresnel structure further comprises a coating that is at least partially reflective.

4. The multifunction optical element according to claim 2 , wherein the Fresnel structure comprises a continuous Fresnel structure.

5. The multifunction optical element according to claim 1 , wherein the Fresnel structure presents facets defining cavities and further comprising a filling material applied to the Fresnel structure such that the cavities are filled by the filling material and the Fresnel structure together with the filling material presents a smooth continuous surface.

6. The multifunction optical element according to claim 5 , wherein the filling material and a material from which a bulk of the multifunction optical element is made are similar material.

7. The multifunction optical element according to claim 1 , wherein the Fresnel structure is formed at a material boundary surface of the multifunction optical element.

8. The multifunction optical element according to claim 1 , wherein optically effective facets of the Fresnel segments optically correspond to an imaginary optical effective surface which is curved and has neither mirror symmetry plane nor rotational symmetry.

9. The multifunction optical element according to claim 1 , wherein a shape of the facets is an approximation of a shape of the corresponding surface section of an imaginary effective surface.

10. A multifunction optical element for a display device, the display device comprising an image-generating module which generates an image, the multifunction optical element comprising:

a coupling-in area and a coupling-out area located separately from the coupling in area;

wherein a structure of the multifunction optical element is such that the image generated by the image-generating module that is coupled into the multifunction optical element via the coupling-in area, is guided in the multifunction optical element along a folded optical path by multiple total internal reflections from the coupling-in area to the coupling-out area and coupled out via the coupling-out area such that a user can perceive the coupled-out image superimposed on surroundings;

wherein the coupling-out area comprises a Fresnel structure which has an imaging property;

the Fresnel structure having several Fresnel segments; and

wherein optically effective facets of the Fresnel segments optically correspond to an imaginary optical effective surface which is curved and has neither mirror symmetry with relation to a center plane nor rotational symmetry with relation to a center axis.

11. The multifunction optical element according to claim 10 , wherein the Fresnel structure is at least partially reflective.

12. The multifunction optical element according to claim 11 , wherein the Fresnel structure further comprises a coating that is at least partially reflective.

13. The multifunction optical element according to claim 11 , wherein the Fresnel structure comprises a continuous Fresnel structure.

14. The multifunction optical element according to claim 10 , wherein the Fresnel structure presents facets defining cavities and further comprising a filling material applied to the Fresnel structure such that the cavities are filled by the filling material and the Fresnel structure together with the filling material presents a smooth continuous surface.

15. The multifunction optical element according to claim 14 , wherein the filling material and a material from which a bulk of the multifunction optical element is made are similar material.

16. The multifunction optical element according to claim 10 , wherein the Fresnel structure is formed at a material boundary surface of the multifunction optical element.

17. The multifunction optical element according to claim 10 , wherein a shape of the facets is an approximation of a shape of the corresponding surface section of an imaginary effective surface.

18. The multifunction optical element according to claim 10 , wherein the coupling-out area receives light from the coupling-in-area via a folded beam path and has an imaging property.