Transparent screen and video image projection system comprising same
[Problem] Provided is a transparent screen which satisfies both the visibility of the projection light and the transmission light by anisotropically scattering and reflecting the projection light emitted from a light source. [Solving means] A transparent screen according to the present invention comprises a light diffusion layer including a binder and microparticles, said transparent screen having a scattered light brilliance profile characterized to meet the following conditions A to C: A: the emitted light relative brilliance in the 0° direction is from 50 to 95, when the entered light relative brilliance is 100; B: the emitted light relative brilliance in the ±5° direction is 1.1 or less, when the emitted light relative brilliance in the 0° direction is 100; and C: the emitted light relative brilliance in the ±50° direction is 0.0005 or higher, when the emitted light relative brilliance in the 0° direction is 100; when the brilliance is Y from the XYZ color system measured with a goniophotometer.
1. A transparent screen comprising:
a light diffusion layer including a binder and microparticles, wherein
the microparticles are light scattering microparticles or light reflecting microparticles,
the light scattering microparticles have a median diameter of from 0.1 to 2500 nm, and the content of the light scattering microparticles in the light diffusion layer is from 0.0001 to 0.6% by mass,
the light reflecting microparticles are bright flake-form microparticles and have an average aspect ratio of from 3 to 800, and the content of the bright flake-form microparticles in the light diffusion layer is from 0.0001 to 5.0% by mass,
said transparent screen having a scattered light brilliance profile characterized to meet the following conditions A to C:
A: the emitted light relative brilliance in the 0° direction is from 50 to 95, when the entered light brilliance is 100;
B: the emitted light relative brilliance in the ±5° direction is 1.1 or less, when the emitted light relative brilliance in the 0° direction is 100; and
C: the emitted light relative brilliance in the ±50° direction is 0.0005 or higher, when the emitted light relative brilliance in the 0° direction is 100;
when the brilliance is Y from the XYZ color system measured with a goniophotometer.
2. The transparent screen according to claim 1 , wherein
when the thickness of the light diffusion layer is t (μm) and the concentration of the microparticles based on the binder is c (% by mass), t and c satisfy the following formula (I):
0.05≤( t×c )≤50 (I).
3. The transparent screen according to claim 1 , wherein
the absolute value of the difference between the refractive index n 1 of the binder and the refractive index n 2 of the light scattering microparticles is 0.1 or higher.
4. The transparent screen according to claim 1 , wherein
the light scattering microparticles are at least one selected from the group consisting of zirconium oxide, zinc oxide, titanium oxide, cerium oxide, barium titanate, strontium titanate, a crosslinkable acrylic resin, a styrene resin, and silica.
5. The transparent screen according to claim 1 , wherein
the light reflecting microparticles have a regular reflectance of from 12 to 100%.
6. The transparent screen according to claim 1 , wherein
the bright flake-form microparticles are metallic microparticles selected from the group consisting of aluminum, silver, platinum, gold, titanium, nickel, tin, tin-cobalt alloy, indium, chromium, titanium oxide, aluminum oxide, and zinc sulfide, a bright material of a glass coated with metal or metal oxide, or a bright material of natural or synthetic mica coated with metal or metal oxide.
7. The transparent screen according to claim 1 , wherein the binder is an organic binder or an inorganic binder.
8. The transparent screen according to claim 7 , wherein the organic binder is a thermoplastic resin or a self crosslinkable resin.
9. The transparent screen according to claim 8 , wherein the thermoplastic resin is at least one selected from the group consisting of an acrylic resin, a polyester resin, a polyolefin resin, a vinyl resin, a polycarbonate resin, and a polystyrene resin.
10. A member for a vehicle comprising the transparent screen according to claim 1 .
11. A member for a building comprising the transparent screen according to claim 1 .
12. A video image projection system comprising the transparent screen according to claim 1 and a projection device which projects an image from the degree of ±10° or higher to the normal direction of the screen surface of the transparent screen.
13. The transparent screen according to claim 1 , wherein the microparticles are the light scattering microparticles, and the content of the light scattering microparticles in the light diffusion layer is from 0.0001 to 0.5% by mass.
14. The transparent screen according to claim 1 , wherein the microparticles are the bright flake-form microparticles, and the content of the light bright flake-form microparticles in the light diffusion layer is from 0.0001 to 0.015% by mass.