Image display device, rear projection type screen used in image display device, Fresnel lens sheet, and method of making Fresnel lens sheet

A method of making a Fresnel lens sheet used in a rear projection type screen for displaying a projection image projected from an optical part, said Fresnel lens sheet including:

• a total reflecting prism portion formed in an area in which the angle of incidence on said Fresnel lens sheet of a projection image projected from said optical part disposed on an image generation source side is at least about 40 degrees, said total reflecting prism portion causing incident light to be outputted as output light at a predetermined output angle by a total reflection phenomenon after a first refraction phenomenon;
• and
• a refracting prism portion formed in an area opposed to the portion where said total reflecting prism portion on an image monitoring side of said Fresnel lens sheet is not formed, said refracting prism portion causing incident light to be outputted as output light at a predetermined output angle by a second refraction phenomenon,
• wherein said refracting prism portion and said total reflecting prism portion are formed by thermocompression-molding both faces of a transparent base such as polymethyl methacrylate or methyl methacrylate/styrene copolymer simultaneously using two molds opposed to each other.

A method of making a Fresnel lens sheet used in a rear projection type screen for displaying a projection image projected from an optical part, said Fresnel lens sheet including:

• a total reflecting prism portion formed in an area where the angle of incidence on said Fresnel lens sheet of a projection image projected from said optical part disposed on an image generation source side is at least about 40 degrees, said total reflecting prism portion causing incident light to be outputted as output light at a predetermined output angle by a total reflection phenomenon after a first refraction phenomenon;
• and
• a refracting prism portion formed in an area opposed to the portion where said total reflecting prism portion on an image monitoring side of said Fresnel lens sheet is not formed, said refracting prism portion causing incident light to be outputted as output light at a predetermined output angle by a second refraction phenomenon,
• wherein said refracting prism portion on the image monitoring side is formed by thermocompression-molding a transparent base such as polymethyl methacrylate or methyl methacrylate/styrene copolymer and thereafter said total reflecting prism portion is formed on the opposite side with use of an ultraviolet curing resin.

A method of making a Fresnel lens sheet used in a rear projection type screen for displaying a projection image projected from an optical part, said Fresnel lens sheet including:

• a total reflecting prism portion formed in an area in which the angle of incidence on said Fresnel lens sheet of a projection image projected from said optical part disposed on an image generation source side is at least about 40 degrees, said total reflecting prism portion causing incident light to be outputted as output light at a predetermined output angle by a total reflection phenomenon after a first refraction phenomenon;
• and
• a refracting prism portion formed in an area opposed to the portion where said total reflecting prism portion on an image monitoring side of said Fresnel lens sheet is not formed, said refracting prism portion causing incident light to be outputted as output light at a predetermined output angle by a second refraction phenomenon,
• wherein a first transparent ultraviolet curing resin layer having the refracting prism portion is formed on a first transparent base, and a second transparent base including a second transparent ultraviolet curing resin layer having the total reflecting prism portion is bonded to the first transparent base using an adhesive layer, said second transparent base being formed on a face opposite to the face where the refracting prism portion is formed.

An image display device comprising:

• an image generation source;
• an optical part for projecting an image from said image generation source on a larger scale;
• and
• a rear projection type screen for displaying a projection image projected thereon from said optical part,
• said rear projection type screen including at least a Fresnel lens sheet disposed on the image generation source side and a diffusion sheet for diffusing an image light to the image monitoring side,
• said Fresnel lens sheet including:
• a total reflecting prism portion formed on the image generation source side of said Fresnel lens sheet, said total reflecting prism portion being formed in an area in which the angle of incidence of the projection image projected from said optical part on said Fresnel lens sheet is at least about 40 degrees, said total reflecting prism portion imparting a predetermined incidence surface output angle to incident light by a total reflection phenomenon after a first refraction phenomenon, and
• a refracting prism portion formed on the image monitoring side of said Fresnel lens sheet, said refracting prism portion outputting light having a predetermined output angle by a second refraction phenomenon.