Projection screen and projection system comprising the same
A projection screen includes a polarized-light selective reflection layer having a cholesteric liquid crystalline structure, capable of selectively diffuse-reflecting a specific polarized-light component; a substrate for supporting the polarized-light selective reflection layer; and an optical member provided on the observation side of the polarized-light selective reflection layer. The optical member diffuses imaging light which the polarized-light selective reflection layer diffuse-reflects, while maintaining the state of polarization of the imaging light. The optical member diffuses right-handed circularly polarized light that is projected on the projection screen, when the light travels from the observation side to the polarized-light selective reflection layer. The diffused light ( 31 a 1 ) enters the polarized-light selective reflection layer and is diffuse-reflected owing to the scattering property of the polarized-light selective reflection layer (the property of diffusing light that is selectively reflected, owing to structural non-uniformity in the cholesteric liquid crystalline structure containing a plurality of helical structure parts, the helical axes of which extend in different directions). The optical member further diffuses this diffused light ( 31 a 2 ) when the light travels from the polarized-light selective reflection layer toward the observation side. The thus diffused light ( 31 a 3 ) finally emerges toward the observation side.
1. A projection screen for displaying an image by reflecting imaging light that is projected from an observation side, the projection screen compnsing:
a polarized-light selective reflection layer that selectively diffuse-reflects a specific polarized-light component; and
a polarization-maintaining light-diffusing layer provided on an observation side of the polarized-light selective reflection layer, the polarization-maintaining light-diffusing layer diffusing imaging light which the polarized-light selective reflection layer diffuse-reflects, while maintaining a state of polarization of the imaging light,
wherein the polarized-light selective reflection layer itself has diffusing properties,
the polarized-light selective reflection layer has a cholesteric liquid crystalline structure and, owing to structural non-uniformity in the cholesteric liquid crystalline structure, diffuses the specific polarized-light component, and
the cholesteric liquid crystalline structure contains a plurality of helical structure parts whose helical axes extend in different directions.
2. The projection screen according to claim 1 , wherein the polarization-maintaining, light-diffusing layer has a roughened surface on a side of the observation.
3. The projection screen according to claim 1 , wherein the polarization-maintaining, light-diffusing layer has a roughened surface on a side of the polarized-light selective reflection layer.
4. The projection screen according to claim 1 , wherein the polarization-maintaining light-diffusing layer is at least one optical member selected from a group consisting of frosted glass and a holographic optical element.
5. The projection screen according to claim 1 , wherein the specific polarized-light component is right- or left-handed circularly polarized light.
6. The projection screen according to claim 1 , wherein the specific polarized-light component is linearly polarized light of one vibration direction.
7. The projection screen according to claim 1 , wherein the polarized-light selective reflection layer comprises a polarized-light selective reflection layer body that reflects the specific polarized-light component, and a diffusing element that diffuses light that is reflected from the polarized-light selective reflection layer body.
8. The projection screen according to claim 1 , further comprising a substrate that supports the polarized-light selective reflection layer.
9. The projection screen according to claim 8 , wherein the substrate is an absorptive substrate comprising a light-absorbing layer adapted to absorb light in a visible region.
10. The projection screen according to claim 8 , wherein the substrate is a transparent substrate adapted to transmit at least part of light in a visible region.
11. The projection screen according to claim 1 , wherein the polarized-light selective reflection layer comprises at least two partial selective reflection layers that are laminated to each other.
12. The projection screen according to claim 11 , wherein an intermediate layer having barrier properties is provided between each neighboring two of the partial selective reflection layers.
13. The projection screen according to claim 11 , wherein an intermediate layer having adherent properties is provided between each neighboring two of the partial selective reflection layers.
14. The projection screen according to claim 1 , further comprising a functional layer containing at least one layer selected from a group consisting of a hard coat layer, an anti-glaring layer, an anti-reflection layer, an ultraviolet-light-absorbing layer and an antistatic layer.
15. A projection system comprising:
a projection screen according to claim 1 ; and
a projector that projects imaging light on the projection screen.