GB320019A - Improvements in or relating to light condensers and projectors - Google Patents

Abstract

320,019. Soc. Anon. des Etablissements Ouvrard, Villars et Perez Reunis, (Assignees of Soc. des Etablissements Gaumont). Sept. 28, 1928, [Convention date]. Bulbs; residual gases.-The brightness of the field illuminated by a source of light is increased by the use of a trumpet shaped reflector by which the beam emitted is partially reflected so that it emerges as a slightly convergent or divergent beam. This reflector is used in conjunction with a source of light enclosed in a bulb the inner surface of which is also reflecting. The device is applied to optical projection apparatus, motor car head lights, &c. In the usual form, Fig. 1, the light source F is contained in a bulb having two inner reflecting surfaces A, B, C and A, F1, C the first being elliptical and the second spherical, so that the whole of the emitted rays is ultimately projected through a clear aperture L, K into the trumpet-shaped reflector L, M, N, K, part of the rays passing directly through it and part being reflected until their angle to the axis is less than that of the reflector. In connection with these reflectors electric bulbs are used in which channels C1, C2, Fig. 4, are provided for the flow of inert gases to prevent blackening near the source of light or the lamp may be formed as in Fig. 3. In a modified form of lamp the reflector 22 is incorporated in the bulb and the outer end 23 of the bulb is formed as a converging meniscus lens. A non-dazzling motor car light is formed by a reflector lamp, Fig. 10, and a flattened trumpet-shaped reflector giving a broad horizontal beam. The reflector may be made of a number of glass blocks, Fig. 8, having a curved end surface so that the beam is caused to converge. When used with an ordinary lamp the trumpet-shaped reflector is fitted at the lamp end with a conical reflector, and an additional curved reflector is provided at the back of the lamp so that a larger proportion of the rays are utilized by the principal reflector. Such an arrangement is used in connection with an ordinary optical projection apparatus, Fig. 9, the reflector 12 being fitted with the conical reflectoras shown.