Optical film

• US 5,903,391 A
• Filed: 03/27/1997
• Issued: 05/11/1999
• Est. Priority Date: 03/27/1996
• Status: Expired due to Term

• Current Assignee: Kimoto Company Limited
• Original Assignee: Kimoto Company Limited
• Inventors: Kato, Takaaki, Toshima, Yasumaro
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): SIKDER, MOHAMMAD YUNUS
• Application Number:
  US08/824,972
• Time in Patent Office: 775 Days
• Field of Search: 359/599, 359/883, 359/884, 359/531, 359/529, 359/530, 359/613, 359/614
• US Class Current: 359/599
• CPC Class Codes: G02B 5/0226 having particles on the surface
• CPC Class Codes: G02B 5/0242 by means of dispersed particles
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G03B 21/625 Lenticular translucent screens

Abstract

An optical film having high light transmittance and excellent light diffusibility is provided. The optical film comprises a transparent substrate 1 and a light diffusion layer 2 formed on one or both sides of the substrate 1. As the resin 3 of the light diffusion layer 2, an ionizing radiation curable resin is used in an amount of, preferably, not less than 50% of the resin and a small amount of the light diffusive agent is dispersed therein. The optical film exhibits excellent light diffusion effect even though the content of the light diffusive agent is small and also exhibits high light transmittance because of the small content of the light diffusive agent. Accordingly, this optical film is suitable for applications such as a color liquid crystal display which is required to have a sufficient brightness, and in combination with another optical material such as a prism lens.

Claims

1. An optical film comprising a transparent substrate and a light diffusion layer formed on at least one side of the substrate, wherein the light diffusion layer comprises an ionizing radiation cured resin as a binder and a light diffusion agent having an average particle size of 1 μ

m to 30 μ

m dispersed in the binder, and at least part of the light diffusion agent protrudes from a surface of the binder.

2. The optical film according to claim 1, wherein the ionizing radiation cured resin is included in an amount of not less than 25% by weight of the binder.

3. A light diffusion sheet comprising a transparent film and a light diffusion layer formed on at least one side of the film, wherein the light diffusion layer comprises an ionizing radiation cured resin as a binder and a light diffusion agent dispersed in the binder, and at least part of the light diffusion agent protrudes from a surface of the binder.

4. The light diffusion sheet according to claim 3, wherein the light diffusion agent has an average particle size of 1 μ

m to 30 μ

m.

5. The light diffusion sheet according to claim 3, wherein the ionizing radiation cured resin is included in an amount of not less than 25% by weight of the binder.