Method for fabricating fresnel lenses by selective application and removal of films on lens surfaces
First Claim
1. A method for fabricating a Fresnel lens having a lens main body for converging light passed through a lens surface comprising the steps of:
- preparing the Fresnel lens main body with a plurality of prisms having lens surfaces and non-lens surfaces facing different directions from each other;
forming a primary film on each lens surface by depositing a material of said primary film only on said lens surfaces;
forming an invalid light absorbing film for restraining transmission of light on said lens surfaces and said non-lens surfaces; and
removing said primary film and the invalid light absorbing film from said lens surfaces.
1 Assignment
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Accused Products
Abstract
Particles of a lens coating material for forming a primary film are deposited from a direction toward which the surfaces of the lens prisms of a Fresnel lens face. Next, a light absorbing film is formed, conventionally, by sputtering, on both the lens surfaces on which the previously deposited primary film was formed and on the non-lens surfaces (on which no primary film was formed). This light absorbing film is intended to absorb types of undesirable or "invalid" light (e.g., "flaring light"). Subsequently, the films are removed from only the lens surfaces. Accordingly, a Fresnel lens having "invalid" light absorbing films only on the non-lens surfaces is more easily fabricated within a shorter time and at a reduced cost. Moreover, it is also possible to reduce the generation of "cone" and "rainbow" effects caused by "flaring light" when the Fresnel lens is used as a field lens of a projection-type image display device.
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Citations
16 Claims
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1. A method for fabricating a Fresnel lens having a lens main body for converging light passed through a lens surface comprising the steps of:
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preparing the Fresnel lens main body with a plurality of prisms having lens surfaces and non-lens surfaces facing different directions from each other; forming a primary film on each lens surface by depositing a material of said primary film only on said lens surfaces; forming an invalid light absorbing film for restraining transmission of light on said lens surfaces and said non-lens surfaces; and removing said primary film and the invalid light absorbing film from said lens surfaces. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for fabricating a Fresnel lens having a lens main body for converging light passed through a lens surface comprising the steps of:
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preparing the Fresnel lens main body with a plurality of prisms having lens surfaces and non-lens surfaces facing different directions from each other; forming a primary film on each lens surface by depositing a material of said primary film only on said lens surfaces; forming an invalid light absorbing film for restraining transmission of light on said lens surfaces and said non-lens surfaces; removing said primary film and the invalid light absorbing film from said lens surfaces; selecting the material of said primary film from the group consisting of iron oxides, Si and Ti; the material of said invalid light absorbing film being selected from the group consisting of metal, oxide, carbon, sublimation pigment, and sublimation dye; and the material of said primary film and the material of said invalid light absorbing film being soluble in different types of solvents.
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16. A method for fabricating a Fresnel lens having a lens main body for converging light passed through a lens surface comprising the steps of:
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preparing the Fresnel lens main body with a plurality of prisms having lens surfaces and non-lens surfaces facing different directions from each other; forming a primary film on each lens surface by depositing a material of said primary film only on said lens surfaces; forming an invalid light absorbing film for restraining transmission of light on said lens surfaces and said non-lens surfaces; removing said primary film and the invalid light absorbing film from said lens surfaces; the material of said primary film being selected from the group consisting of aluminum metal; the material of said invalid light absorbing film being selected from the group consisting of sublimation pigment, sublimation dye, metal, oxide and carbon, said metal, oxide and carbon being insoluble in alkaline solvents; the material of said primary film and the material of said invalid light absorbing film being soluble in different types of solvents; and said primary film being caused to dissolve in said alkaline solvents in the step of removing said primary film from said lens surfaces.
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Specification