Optical sheet
An optical sheet includes a substrate, a light diffusion layer formed on the substrate, and a light gathering layer formed on the light diffusion layer. The light diffusion layer includes a polymeric resin having a plurality of bubbles mixed therein. The light gathering layer has at least one microstructure. The optical sheet of the subject invention can be used in LCD's as a photo-diffusive brightness enhancement film.
1. An optical sheet, comprising:
a plastic substrate;
a light diffusion layer formed on said substrate, and comprising a UV curable resin having bubbles mixed therein; and
a light gathering layer formed on said light diffusion layer by applying a composition on said light diffusion layer, said light gathering layer having at least one microstructure, that is selected from a group consisting of a regular prismatic pattern, an irregular prismatic pattern, an annular prismatic pattern, and a cube corner pattern,
wherein the UV curable resin is an acrylic UV curable resin selected from the group consisting of methacrylate resin, urethane acrylate resin, polyester acrylate resin, and mixtures thereof, and wherein said composition is made from polyacrylate resin,
and wherein the bubbles have an irregular distribution of volumes within the light diffusion layer.
2. The optical sheet of claim 1 , wherein the microstructure is the regular prismatic pattern.
3. The optical sheet of claim 1 , wherein said plastic substrate is selected from the group consisting of polyethylene terephthalate (PET) resin, polymethyl methacrylate (PMMA) resin, polyethylene (PE) resin, polypropylene (PP) resin, polyimide resin, polycarbonate resin, polyurethane (PU) resin, and mixtures thereof.
4. The optical sheet of claim 3 , wherein said plastic substrate is selected from the group consisting of polyethylene terephthalate (PET) resin, polymethyl methacrylate (PMMA) resin, and mixtures thereof.
5. The optical sheet of claim 1 , wherein said UV curable resin includes a blowing agent which when activated foams the UV curable resin to form the bubbles.
6. The optical sheet of claim 5 , wherein said blowing agent is activated by heat or UV-irradiating.
7. The optical sheet of claim 1 , wherein said composition includes a photoinitiator and a cross-linking agent.
8. The optical sheet of claim 1 , wherein said composition is applied to said light diffusion layer in an uncured form.
9. The optical sheet of claim 8 , wherein said at least one microstructure is molded onto said uncured composition during a curing process.
10. The optical sheet of claim 1 , wherein said at least one light gathering layer is directly touching said light diffusion layer.
11. The optical sheet of claim 1 , wherein the microstructure is the annular prismatic pattern.