Unique prismatic element and projection system

Claim 2

A compact motion picture film handling cassette configured to be mounted in a projector to facilitate film projection operations, such projector having means for forming a beam of light tending to converge at a point a given distance therefrom, comprising: a housing having a pair of spaced apart substantially parallel external wall members connected together by a transverse external wall member adjacent juxtaposed edges thereof, one of said substantially parallel external wall members having an opening provided therethrough adjacent said transverse wall member, said transverse wall member being relatively short to provide a generally thin configuration to said housing and said housing defining a space in which a coiled strip of motion picture film may be initially positioned; a film gate provided in said transverse wall member adjacent said opening; means responsive to drive means of such projector for facilitating the advancement of such strip of film within said housing from said space across said film gate; and light reflecting means, mounted within said housing to be located behind the section of such strip of film disposed across said film gate during advancement of such strip of film within said housing and in operative relationship to said opening to receive substantially the entire converging beam of light from such light beam forming means through said opening when said cassette is mounted in such projector, for redirecting such beam of light through such section of such strip of film and said film gate and for increasing the geometrical distance between such light beam forming means and the point at which such beam of light converges, said light reflecting means including a prism formed of a material having an index of refraction greater thaN air and having a first transparent face disposed to receive such beam of light and a second convex transparent face disposed adjacent such section of such strip of film to minimize the dimensions of said prism in the plane normal to said external wall members and thus permit the thickness of said housing to be minimized.

Claim 3

The cassette of claim 1 wherein said first transparent face of said prism is concave in configuration.

Claim 4

The cassette of claim 2 wherein said prism has a low power factor.

Claim 5

The cassette of claim 1 wherein said prism folds said beam of light 90*.

Claim 6

The cassette of claim 1 wherein said convex transparent face of said prism is radially symmetric.

Claim 7

The cassette of claim 2 wherein said convex and concave transparent faces of said prism are radially symmetric.

Claim 8

A photographic system comprising: a cassette including: a housing having a pair of spaced apart substantially parallel external wall members connected together by a transverse external wall member adjacent juxtaposed edges thereof, one of said substantially parallel external wall members having an opening provided therethrough adjacent said transverse wall member, said transverse wall member being relatively short to provide a generally thin configuration to said housing and said housing defining a space in which a coiled strip of motion picture film may be initially positioned; a film gate provided in said transverse wall member adjacent said opening; first means responsive to drive means of a projector for facilitating the advancement of such strip of film within said housing across said film gate; a projector comprising: a projection lens; means for mounting means for forming a beam of light tending to converge at a point a given distance therefrom; means for mounting said cassette with its said opening in operative relationship with such light beam forming means and its said film gate in operative relationship with said projection lens; means for driving said first means of said cassette when said cassette is mounted in said projector; and light reflecting means positioned within said cassette at least when said cassette is mounted in said projector to be located behind the section of such strip of film disposed across said film gate during advancement of such strip of film within said housing and in operative relationship to said opening to receive substantially the entire converging beam of light from such light beam forming means through said opening when said cassette is mounted in said projector, for redirecting such beam of light through such section of such strip of film and said film gate and for increasing the geometrical distance between such light beam forming means and the point at which such beam of light converges, said light reflecting means including a prism formed of a material having an index of refraction greater than air and having a first transparent face disposed to receive such beam of light and a second convex transparent face disposed adjacent such section of such strip of film to minimize the dimensions of said prism in the plane normal to said external wall members and thus permit the thickness of said housing to be minimized.

Claim 9

A photographic system comprising: a cassette including: a housing having a pair of spaced apart substantially parallel external wall members connected together by a transverse external wall member adjacent juxtaposed edges thereof, one of said substantially parallel external wall members having an opening provided therethrough adjacent said transverse wall member, said transverse wall member being relatively short to provide a generally thin configuration to said housing and said housing defining a space in which a coiled strip of motion picture film may be initially positioned; a film gate provided in said transverse wall member adjacent said opening; first means responsive to drive means of a projector for facilitating the advancement of such strip of film within said housing across said film gate; a projector comprising: a projection lens; means for mounting means for forming a beam of light tending to converge at a point a given distance therefrom; means for mounting said cassette with its said opening in operative relationship with such light beam forming means and its said film gate in operative relationship with said projection lens; means for driving said first means of said cassette when said cassette is mounted in said projector; and light reflecting means positioned within said cassette at least when said cassette is mounted in said projector to be located behind the section of such strip of film disposed across said film gate during advancement of such strip of film within said housing and in operative relationship to said opening to receive substantially the entire converging beam of light from such light beam forming means through said opening when said cassette is mounted in said projector, for redirecting such beam of light through such section of such strip of film and said film gate and for increasing the geometrical distance between such light beam forming means and the point at which such beam of light converges, said light reflecting means including a prism formed of a material having an index of refraction greater than air and having a first transparent face disposed to receive such beam of light and a second convex transparent face disposed adjacent such section of such strip of film to minimize the dimensions of said prism in the plane normal to said external wall members and thus permit the thickness of said housing to be minimized.

Claim 10

The system of claim 7 wherein said first transparent face of said prism is concave in configuration.

Claim 11

The system of claim 7 wherein said convex transparent face of said prism is radially symmetric.

Claim 12

The system of claim 8 wherein said convex and concave transparent faces of said prism are radially symmetric.