GB1222167A - Method and apparatus for controlling colour temperature of an object - Google Patents

Abstract

1,222,167. Photo-electric colour temperature investigation. INSTITUT METALLURGII IM A. A. BAIKOVA. Dec. 18, 1968, No. 60189/68. Heading G1A. [Also in Division G3] A method for controlling the colour temperature of an object by its radiation from which at least two radiation fluxes of different spectral components are selected, comprises transforming the fluxes or corresponding signals so as to equalize them when the object reaches a determined temperature, deviation from this value being arranged to produce a signal controlling a heater in order to reduce such deviation. An optical input element 1 receives radiant flux from an object which is passed through a set point adjusting member 2 which adjusts the ratio of radiation fluxes dependent upon the colour temperature, the setting being effected manually by a mechanism 3 furnished with a scale 4, to a monochromator 5 which separates from the total flux irradiation fluxes having the requisite spectral composition. Irradiation fluxes are passed through a modulator 6, to a receiver 7 e.g. a photo or thermo electric or bolometer transducer which converts the fluxes into electric signals which are compared with a voltage-reference source 8 and pass to an output stage 10 which supplies a heater through terminals 11. The adjusting member 2 comprises a selective absorber i.e. a colour wedge 12 characterized by a Z-shaped spectral transmission factor/wave length curve, and a non-selective absorber 13 rigidly linked to the wedge, the absorber having a variable transmission factor. The modulator 6 is made in the form of a shutter having apertures and non- transmitting areas disposed between them. The member 2 may be adjusted manually or by a programme control arrangement (not disclosed).