GB500759A - Studio lamp - Google Patents

Abstract

500,759. spot and Rood lamps mounting lenses and electric lamps. MOTION PICTURE ELECTRIC PRODUCTS. Dec. 28, 1937, No. 35884. Convention date, Dec. 28, 1936. [Classes 75 (ii) and 75 (iv)] A studio lamp, adapted for use both as a spot and Hood lamp, comprises a main reflector 24 and a Fresnel-type lens 40 disposed on a common optical axis respectively behind and In front of an electric lamp bulb 30 which has the centre of its filament f on the common axis, means being provided for effecting simultaneous relative movement between the bulb 30 and the reflector 24 and between the lens 40 and the reflector, the latter movement taking place at a greater speed than the former. In the form shown, the bulb 30 and lens 40 are mounted on carriages 31, 42 each having a three-bearing support 37, 39 and 43, 45 on a pair of parallel rods 34, 35 along which the carriages are traversed, towards or away from the fixed reflector 24, by operation of a knob 57 on the outer end of a shaft 50. The motion of the latter is transmitted to the lamp carriage 31 by arm 52 and link 53, while the mechanism for moving the lens carriage 42 in the same direction at a greater speed comprises a pivoted lever 70 connected at its upper end by a link 76 to the carriage 42 and, at a point intermediate its ends, by a link 80 to the carriage 31. The latter carriage has rigidly mounted thereon a bracket 48 carrying a small spherical reflector 49. To prevent leakage of light when the bulb 30 and lens 40 are moved to floodlighting position, the prism surfaces 94 on the outer face of the lens are rendered opaque. A modification is described in which the mechanism for traversing the carriages 31, 42 comprises a manually-operable screwed rod having two threads of different pitch engaging in internally screwed lugs depending from the two carriages.