GB401963A - Improved manufacture of multi-colour light filters - Google Patents

Abstract

401,963. Filters for colour photography. I. G. FARBENINDUSTRIE AKT.-GES., Frankfort-on-Main, Germany. April 7, 1933, No. 10465. Convention date, April 7, 1932. [Class 98 (ii).] Multicolour light filters having juxtaposed colour areas, e.g. in the form of parallel strips, are formed by casting at least one of the filter layers on to each of two cover glasses, drying the layer, and giving it the desired form. When several layers are used, the colours cast on each glass are those which, in the finished filter, alternate with those on the other glass. Fig. 3 shows a cover glass on which black layers s and a green layer g have been cast and dried, and then trimmed to shape as with a knife or scraper. Fig. 4 shows the other cover glass, on which blue and red layers b, r have been cast and trimmed so as to fit accurately the transparent areas a of the first glass. The two glasses, when superimposed, produce a tricolour band filter r, g, b with a black segment s on each side. A casting solution for a red filter layer is specified.