GB174747A - Improvements in or relating to the projection of coloured light - Google Patents

Abstract

174,747. Klein, A. B. Nov. 3,1920 Lighting, systems of; projectors; lantern shutters.-A method of projecting coloured light especially for stage lighting consists in dispersing the light from an artificial source into a spectrum and selecting one or more portions of the spectrum for projection by one or more lenses. Light from a source 1, Fig. 1, passes through a condenser 2, a slit 3, a collimator 4 and a constant deviation or dispersion prism 5. The spectrum formed is received by a collimator 6 having an adjustable slit 7. The light passing through the slit 7 is projected by a condensing lens 8 on the object 9 to be illuminated. The prism 5 is preferably mounted on a rotary table 10 with a micrometer adjustment 12, by adjusting which and the movable edge of the slit 7 any desired portion of the spectrum may be employed. Instead of the prism being rotatable, both edges of the slit may be adjustable. In a modification, Fig. 2, the slit 7 is replaced by a number of parallel shutters a-k which are hinged to a rod L and arranged so as to fall in alternate directions, bars m, n, o carried by end nieces p, q acting as stops. The lower end of each shutter is provided with a short crank pivotally connected to a vertical arm which is pivoted at its lower and to one end of a spring M carrying the armatures N of one of a series of electromagnets a<1>-k<1>. The coils of each electromagnet are connected to a common brass strip s and to one of the terminals a<2>-k<2>. The controlling-apparatus for the shutters comprises a short piano keyboard with keys P, Q, which are pivoted at R and supported by springs S, and have at their undersides a brass or copper strip T connected by a wire U to terminals connected by wires to the corresponding terminals a<2>-k<2>. Beneath the keys P, Q is a continuous bar V connected by a wire W to a battery X. To enable a particular colour to be projected for a long period without continually holding down a key P or Q, each key has a corresponding switch A having a stem carrying a blade B adapted to bridge contacts C, D, which are connected in parallel with the strip T and bar V. The coloured light may be diluted with white light from an ordinary projecting lantern, and the shutters may be operated by mechanical means without the use of electrical apparatus. A number of sets of projecting-apparatus may be operated from a single keyboard. Specification 166,028, [Class 98 (ii), Photographic processes &c.], is referred to.