To prevent the sticking of dust, etc., to a central part by forming a region on which light from a light source arranged in the rear of a Fresnel lens is converged with a reflector and further, whose temp. becomes high with radiant heat, to a shape like consecutive curved surfaces or a plane.
The Fresnel lens 6 is fixed in a casing in the front surface of a light emitting part consisting of the reflector and the light source, the recessed and projection parts of the surface of the lens 6 subdivide the curved surface of the lens into concentric lens curved surface parts 1. Then, each gap between the curved surface parts 1 is connected with wall surface parts 2 and as a whole, formation to a plane shape is attained. Further, the central part 3 of the lens 6 being in the highest degree of a flash and in the positional relation nearest to the light source is constituted to be in the shape like the consecutive curved surfaces or the plane. Thus, the dust, soil, etc., are hardly stuck. Or even if they are stuck, they are easily removed, to prevent the generation of heat caused by the dust, soil, etc., in the conventional manner, the deformation of the lens 6 caused by the generation of the heat, etc.
KOBAYASHI KEIAI
IWAMOTO HIROSHI
