| 摘要 |
PROBLEM TO BE SOLVED: To provide a vehicle-mounted cabin lighting device that eliminates thermal damage to a Fresnel lens, capable of illuminating arbitrary positions within a cabin, by causing light radiated from LED to penetrate the entire surface of the Fresnel lens without providing a reflecting plate, and causing a concave lens or a convex lens to achieve their functions depending on usage purposes, and thus has fulfilled more compactness than before.SOLUTION: The vehicle-mounted cabin lighting device includes an LED mounted on a substrate, a case of which base is fixed to an peripheral edge of the substrate on which the LED has been mounted, and a Fresnel lens in a flat plate shape with uniform plate thickness formed of translucent thermoplastic resin on a top surface of the case. The Fresnel lens is formed by varying a vertical height of a lens cut of the Fresnel so that it gradually increases from flat zero state in the center part toward an outermost circumference, in the respective coaxial circle regions formed toward the outermost circumference at equal pitches, taking a specific position of an inner surface of a flat plate with the uniform plate thickness as the center part. |
