| 摘要 |
PURPOSE:To effectively utilize light radiated from a lamp bulb, by disposing a bulb at the first focal point of a reflector having disposed in a lamp housing, and by disposing an inner lens composed of two-kinds of prisms, between the bulb in the lamp housing and an outer lens. CONSTITUTION:A lamp housing 12 storing a socket for holding a reflector 14 and a bulb 16 is provided in a room lamp 10, and an outer lens 18 is attached to the lamp housing 12 so that the lens 18 covers the opening of the housing 12, an inner lens 22 having an opening 20 in its center section being disposed between the bulb 16 and the outer lens 12. In this arrangement, the reflector 14 is constructed such that a reflecting layer 14 is formed on an elliptic surface in the lamp housing 12. Further, the bulb 16 is located at the first focal point F1. Further, the inner lens 22 is composed of fresnel type first prisms 22a, and second prisms 22b refracting right lays which are converted to the second focal point F2 of the reflector 14 to form a secondary light source of the bulb 16, into a specific direction.
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