Projection screen
First Claim
1. A projection screen for a rear projection type television set, having a plurality of lens sheets arranged in the order of a lenticular lens sheet, a linear Fresnel lens sheet, and a circular Fresnel lens sheet when seen from a viewer'"'"'s side, wherein a lens angle ψ
- of said linear Fresnel lens sheet is obtained in accordance with the following expressions;
##EQU5## where;
θ
.sub. ;
Incident light angleθ
;
Outgoing light angleψ
;
Linear Fresnel lens anglenL ;
Linear Fresnel lens refractive indexφ
;
Circular Fresnel lens anglev;
Vertical coordinate value of linear Fresnel lensnc ;
Circular Fresnel lens refractive indexf1 ;
Projection distancef2 ;
Vertical light converging distancePJ;
Vertical coordinate value of light source (A) (CRT)hf ;
Vertical coordinate value of image formation point.
1 Assignment
0 Petitions
Accused Products
Abstract
In a projection screen for a rear projection type television set, three lens sheets are arranged in the order of a lenticular lens sheet, a linear Fresnel lens sheet, and a circular Fresnel lens sheet when seen from a viewer'"'"'s side toward a projector tube. As compared with the arrangement in which the linear and circular Fresnel lens sheets are exchanged with each other, it is possible to obtain a higher brightness and a more uniform brightness, and color uniformity in the picture plane. Further, when the light incident surface of the linear Fresnel lens sheet is matted, it is possible to eliminate white bands (seen from the viewer'"'"'s side) effectively.
49 Citations
9 Claims
-
1. A projection screen for a rear projection type television set, having a plurality of lens sheets arranged in the order of a lenticular lens sheet, a linear Fresnel lens sheet, and a circular Fresnel lens sheet when seen from a viewer'"'"'s side, wherein a lens angle ψ
- of said linear Fresnel lens sheet is obtained in accordance with the following expressions;
##EQU5## where;
θ
.sub. ;
Incident light angleθ
;
Outgoing light angleψ
;
Linear Fresnel lens anglenL ;
Linear Fresnel lens refractive indexφ
;
Circular Fresnel lens anglev;
Vertical coordinate value of linear Fresnel lensnc ;
Circular Fresnel lens refractive indexf1 ;
Projection distancef2 ;
Vertical light converging distancePJ;
Vertical coordinate value of light source (A) (CRT)hf ;
Vertical coordinate value of image formation point. - View Dependent Claims (2)
- of said linear Fresnel lens sheet is obtained in accordance with the following expressions;
- 3. A projection screen for a rear projection type television set, having a plurality of lens sheets in the order of a lenticular lens sheet, a linear Fresnel lens sheet, and a circular Fresnel lens sheet when seen from a viewer'"'"'s side, said circular Fresnel lens sheet having a refractive index larger than that of said linear Fresnel lens sheet.
-
5. A projection screen for a rear projection type television set, having a plurality of lens sheets arranged in the order of a lenticular lens sheet, a linear Fresnel lens sheet in the form of a film, and a circular Fresnel lens sheet when seen from a viewer'"'"'s side, wherein at least said lenticular lens sheet and said circular Fresnel lens sheet are curved, and said linear Fresnel lens sheet is sandwiched between said circular Fresnel lens sheet and said lenticular lens sheet.
- 6. A projection screen for a rear projection type television set, having a plurality of lens sheets arranged in the order of a lenticular lens sheet, a linear Fresnel lens sheet in the form of a film, and a circular Fresnel lens sheet when seen from a viewer'"'"'s side, wherein said linear Fresnel lens sheet is composed of a base film and a lens group formed on said base film, said lens group comprising at least one of ultraviolet-ray hardening type resins and electron-beam hardening type resins.
Specification