# US 4,399,455 A · Television viewer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,399,455 A - Document ID: US4399455A - Status: Granted - Kind: A - Application number: 06/274,760 - Filed: 1981-06-18 - Granted: 1983-08-16 - Earliest claimed: 1979-07-09 - Inventors: Luis W. Alvarez - Web page: https://patentgrep.com/patent/US4399455A ## CPC - H04N 9/31: Projection devices for colour picture display {, e.g. using electronic spatial light modulators [ESLM]} - G03B 21/62: Translucent screens - G03B 21/625: Lenticular translucent screens - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D) ## Abstract A viewing system for use with a cathode ray tube display comprising an objective lens which focuses the display image onto a limited light diverging screen having orthogonally arranged lenticular lenses on its opposite planar surfaces and which diverts the projected light to produce an image of maximum brightness in a hypothetical ellipse having a major dimension of six inches and minor dimension of two inches at a viewing distance of sixteen inches. ## Claims ### Claim 1 A viewing system for use by a single viewer of a single electronic display comprising a projection lens having an aperture, a limited, light diverging screen viewed by the viewer, the screen having a Fresnel lens means incorporated therein with a front face and a rear face which optically faces the projection lens, wherein the projection lens projects the light image from the single electronic display onto the Fresnel lens means, the Fresnel lens means comprising a first set of parallel, straight lens Fresnel lens elements on the rear face and a second set of parallel, straight line Fresnel lens elements on the front face which are arranged orthogonal to the first elements, at least some of said first and second elements being contoured to act as a combined simple field lens for focusing an image of the projection lens aperture at an exit pupil located at a predetermined viewing distance from the screen while simultaneously spreading the image over an oval shaped area having predetermined minor and major axial dimensions and which is contained in a plane, parallel to the screen and located at the predetermined viewing distance from the screen, with substantially all of the light image passing through the projection lens hitting the exit pupil. ### Claim 2 (depends on 1) A viewing system as recited in claim 1 wherein the projection lens is bifurcated into separate halves and further comprising a rotatable, color filter wheel mounted to rotate in a plane located between the halves of the projection lens. ### Claim 3 (depends on 2) A viewing system as recited in claim 2 wherein the bifurcated projection lens comprises a pair of Cook triplet lenses taken back to back. ### Claim 4 (depends on 2) A viewing system as recited in claim 2 wherein the bifurcated objective lens comprises a double Gauss lens. ### Claim 5 (depends on 1) A viewing system as recited in claim 1 wherein the predetermined viewing distance is sixteen inches and the predetermined minor and major axial dimensions are two inches and six inches, respectively. ### Claim 6 (depends on 1) A viewing system as recited in claim 1 further comprising a rotatable, color filter wheel mounted to rotate in a plane which is perpendicular to, and intersected by the optical axis, with the diameter of the wheel being smaller than the height of the screen, and with the term height being taken in respect to a viewer of the screen. ### Claim 7 (depends on 1) A viewing system as recited in claim 1 wherein the predetermined viewing distance is sixteen inches and the predetermined minor and major axial dimensions are two inches and six inches, respectively. ### Claim 8 (depends on 1) A viewing system as recited in claim 1 wherein the maximum width of the straight line Fresnel lens elements is 0.0047 inches. ### Claim 9 (depends on 1) A viewing system as recited in claim 1 in combination with a field sequential, cathode ray tube display means for displaying black and white images in a predetermined sequence corresponding to predetermined colored images and further comprising a rotating color wheel having a plurality of individual colored segments, the rotating wheel being synchronized in its rotation with the predetermined color fields being displayed and being located near the projection lens such that the display image passes through the corresponding colored individual segments of the wheel as it rotates. ### Claim 10 (depends on 9) The combination recited in claim 9 wherein the diameter of the color wheel does not exceed the height of the screen, with the term height being taken with respect to the viewer of the screen. ### Claim 11 (depends on 1) A viewing system as recited in claim 1 wherein both the first and second sets of Fresnel lens elements are stepped grooves, the risers of which have plane front surfaces, are of progressively decreasing slope toward the center of the rear and front faces of the screen, face away from the center of the rear and front faces of the screen, and have superimposed thereon a concave cylindrical lens surface. ### Claim 12 (depends on 1) A viewing system as recited in claim 1 wherein both the first and second sets of Fresnel lens elements are stepped grooves, the risers of which have plane front surfaces, are of progressively decreasing slope toward the center of the rear and front faces of the screen, face away from the center of the rear and front faces of the screen, and have superimposed thereon a convex cylindrical lens surface.