Optical element and display device
An optical element includes a plurality of reflectivity variation partially reflecting mirrors and a light-transmittance member, and the plurality of reflectivity variation partially reflecting mirrors have a plurality of regions having different reflectivity in an inclination direction. The plurality of regions include at least a low reflectivity region positioned on a side far away from an emission surface and a high reflectivity region positioned on a side close to the emission surface. An occupation area of the high reflectivity region of the reflectivity variation partially reflecting mirror positioned far away from an incidence portion is larger than an occupation area of the high reflectivity region of the reflectivity variation partially reflecting mirror positioned on a side close to the incidence portion.
1. An optical element comprising:
a plurality of reflectivity variation partially reflecting mirrors that are provided so as to be parallel to each other with a space therebetween, reflect a part of image light incident from an incidence portion, and make the other part of the image light transmit therethrough; and
a light-transmittance member that supports the plurality of reflectivity variation partially reflecting mirrors,
wherein the light-transmittance member includes an incidence surface on which the image light is incident and an emission surface from which the image light is emitted,
wherein each of the plurality of reflectivity variation partially reflecting mirrors is disposed to be inclined with respect to the incidence surface and the emission surface,
wherein the plurality of reflectivity variation partially reflecting mirrors include a plurality of regions having different reflectivity in an inclination direction,
wherein the plurality of regions of each of the plurality of reflectivity variation partially reflecting mirrors include at least a low reflectivity region that is positioned on a side far away from the emission surface in the inclination direction and a high reflectivity region that is positioned on a side closer to the emission surface than the low reflectivity region in the inclination direction and has a higher reflectivity than reflectivity of the low reflectivity region, and
wherein an occupation area of the high reflectivity region in the reflectivity variation partially reflecting mirror that is positioned on a side far away from the incidence portions is larger than an occupation area of the high reflectivity variation region of the reflectivity variation partially reflecting mirror that is positioned on a side close to the incidence portions in the plurality of reflectivity variation partially reflecting mirrors.
2. The optical element according to claim 1 , wherein the occupation area of each of the high reflectivity regions in the plurality of reflectivity variation partially reflecting mirrors gradationally increases from the side close to the incidence portion toward the side far away from the incidence portion.
3. The optical element according to claim 1 , wherein the occupation area of each of the high reflectivity regions in the plurality of reflectivity variation partially reflecting mirrors linearly increases from the side close to the incidence portion toward the side far away from the incidence portion.
4. The optical element according to claim 1 , wherein, when reflectivity of the high reflectivity region is referred to as R 1 , reflectivity of the low reflectivity region is referred to as R 2 , and a reflectivity difference parameter Φ is defined by following equation (1) of Φ=(R 1 −R 2 )/[(R 1 +R 2 )/2], the reflectivity difference parameter Φ satisfies 0.1<Φ<0.7 . . . (1).
5. The optical element according to claim 1 , further comprising:
a reflectivity constant partially reflecting mirrors that is provided in parallel with each of the plurality of reflectivity variation partially reflecting mirrors.
6. The optical element according to claim 5 , wherein the reflectivity constant partially reflecting mirror is disposed so as to be parallel to the plurality of reflectivity variation partially reflecting mirrors between two adjacent reflectivity variation partially reflecting mirrors among the plurality of reflectivity variation partially reflecting mirrors.
7. The optical element according to claim 1 , wherein the high reflectivity regions and the low reflectivity regions in the plurality of reflectivity variation partially reflecting mirrors linearly varies.
8. A display device comprising:
an image forming device; and
a light guiding device that guides image light that is generated by the image forming device,
wherein the light guiding device includes an incidence portion on which the image light is incident, a light guiding body which guides the image light incident from the incidence portion, and an emission portion from which the image light is emitted, and
wherein the emission portion includes the optical element according to claim 1 .
9. A display device comprising:
an image forming device; and
a light guiding device that guides image light that is generated by the image forming device,
wherein the light guiding device includes an incidence portion on which the image light is incident, a light guiding body which guides the image light incident from the incidence portion, and an emission portion from which the image light is emitted, and
wherein the emission portion includes the optical element according to claim 2 .
10. A display device comprising:
an image forming device; and
a light guiding device that guides image light that is generated by the image forming device,
wherein the light guiding device includes an incidence portion on which the image light is incident, a light guiding body which guides the image light incident from the incidence portion, and an emission portion from which the image light is emitted, and
wherein the emission portion includes the optical element according to claim 3 .
11. A display device comprising:
an image forming device; and
a light guiding device that guides image light that is generated by the image forming device,
wherein the light guiding device includes an incidence portion on which the image light is incident, a light guiding body which guides the image light incident from the incidence portion, and an emission portion from which the image light is emitted, and
wherein the emission portion includes the optical element according to claim 4 .
12. A display device comprising:
an image forming device; and
a light guiding device that guides image light that is generated by the image forming device,
wherein the light guiding device includes an incidence portion on which the image light is incident, a light guiding body which guides the image light incident from the incidence portion, and an emission portion from which the image light is emitted, and
wherein the emission portion includes the optical element according to claim 5 .
13. A display device comprising:
an image forming device; and
a light guiding device that guides image light that is generated by the image forming device,
wherein the light guiding device includes an incidence portion on which the image light is incident, a light guiding body which guides the image light incident from the incidence portion, and an emission portion from which the image light is emitted, and
wherein the emission portion includes the optical element according to claim 6 .
14. A display device comprising:
an image forming device; and
a light guiding device that guides image light that is generated by the image forming device,
wherein the light guiding device includes an incidence portion on which the image light is incident, a light guiding body which guides the image light incident from the incidence portion, and an emission portion from which the image light is emitted, and
wherein the emission portion includes the optical element according to claim 7 .
15. The display device according to claim 8 , wherein the emission portion is provided on a surface on a side on which the light guiding body is viewed.
16. The display device according to claim 9 , wherein the emission portion is provided on a surface on a side on which the light guiding body is viewed.
17. The display device according to claim 10 , wherein the emission portion is provided on a surface on a side on which the light guiding body is viewed.
18. The display device according to claim 11 , wherein the emission portion is provided on a surface on a side on which the light guiding body is viewed.
19. The display device according to claim 12 , wherein the emission portion is provided on a surface on a side on which the light guiding body is viewed.
20. The display device according to claim 13 , wherein the emission portion is provided on a surface on a side on which the light guiding body is viewed.