Patent GB-520477-A (GB)
Title: Photographic printing processes
IPC: G03C7/00
Filed: 1938-07-23
Abstract: 520,477. Photographic printing. GASPAR, B. July 23, 1938, No. 21934. [Class 98 (ii)] To enable an image to be printed from a coloured photographic record on to a light-sensitive silver halide emulsion printing layer sensitized to light other than that by which the record is illuminated for printing, use is made of either (1) a fluorescent or phosphorescent screen illuminated through the record with light substantially transmitted by the most transparent portions of the record and substantially absorbed by the least transparent portions, the screen being responsive to such light to emit light of a different spectral composition, including light to which the printing layer is sensitive, or (2) a device illuminated through the record with light substantially transmitted and absorbed as above and similarly responsive, e.g., through a photoelectric device, to emit light of a different spectral composition including light to which the printing layer is sensitive. Fig. 1 represents the printing by method (1) above of three superimposed part-images of, in layers 4, 3, 2, coloured yellow, magenta and blue-green respectively, an original film 1 into a printing material film 1<SP>1</SP> comprising three light-sensitive layers 2<SP>1</SP>, 3<SP>1</SP>, 4<SP>1</SP>, dyed yellow, magenta and bluegreen respectively, each film being moved intermittently in the direction of the arrow into the positions for printing the successive pictures. Picture I is positioned between a light source 6 with a blue filter 7 and the printing material 1<SP>1</SP> with a green filter 9, and a fluorescent screen 8. between the original 1 and the filter 9, carries 4-amino-fluoranthene which emits green light under the action of the incident blue light transmitted by filter 7 and absorbed and transmitted in accordance with part-image Y'. The green light so emitted acts on the green sensitive layer 2<SP>1</SP> of the printing material to produce therein a latent print of Y<SP>1</SP>. Pictures II and III are correspondingly positioned in relation to light sources 10 and 14 with filters 11 and 15 and in relation to filters 13 and 17 with interposed fluorescent screens 12 and 16 carrying Acid rhodamine and zaponechtblau 3G respectively and a latent print of M" is therefore produced in layer 3' and a latent print of G<SP>111</SP> in layer 4<SP>1</SP> of the printing material. When the films move into the next two printing positions a latent print is similarly produced successively in the second and third layers of the printing material for each picture and on developing, fixing and subjecting to local dye destruction where silver is present, e.g., as described in Specifications 395,718, 397,159, 397,188 and 397,192, a series of positive threecolour pictures is obtained. As illustrating method (2), above, the light passed through the record 1, Fig, 2, may be concentrated by a lens 23 on the image screen 18 of a cathode ray tube' to control a photoelectric device 20 controlling the illumination of the fluorescent screen 19 of a Braun tube, such illumination being concentrated by a lens 24 on the printing layer 1<SP>1</SP> and synchronized rotary colour filters 21, 22 being arranged as shown, the filter 21 comprising sectors transmitting blue, green and red in line with sectors of the filter 22 transmitting green, red and infra-red respectively. Specifications 406,294 and 408,991 also are referred to.