GB589971A - Improvements in or relating to kinematographic projection with continuously moving film - Google Patents

Abstract

589,971. Kinematograph projectors. SCOPHONY, Ltd., WIKKENHAUSER, G., and ADAMS, A. E. Jan. 22, 1945, No. 1734. [Class 97 (i)] A kinematograph projector for continuously moving films comprises mechanism for advancing the film continuously and synchronized means for illuminating each frame of the film by a small plurality of flashes of duration so short that the movement of the projected picture produced by movement of the film during a flash is, without any compensation for such movement, within the definition required and compensating means for changing the optical path from the film to the projecting light beam to compensate for the movement of the film between successive flashes in each frame period. The flashes may be produced by a continuous light source and a shutter or a flashing light source such as a high pressure mercury vapour lamp with or without a shutter. The shutter may be a "wave slot " cell of the type described in Specification 474,970, [Group XL], operated by electrical impulses generated in synchronism with the film movement. The form shown in Fig. 2 comprises lamp 1, condenser 2 and projection lens 7. Two flashes per frame are used and the optical compensator comprises two parallel-sided blocks 3, 4 inclined to the optic axis and held in a frame 14 oscillated vertically by a cam 9 to bring them successively into the light path. The cam 9 is carried on the same shaft as the film feed sprocket and also carries a pair of diametrically opposite contacts 12 co-operating with brushes 13 to produce the flashes in the lamp. A number of alternative arrangements of prisms and mirrors for deflecting the light beam are described. Fig. 7 shows an arrangement for bringing three-light deflecting elements 24, 25, 26 in succession into the light beam. The elements are/mounted in a disc 27 carried on rotating cranks 28. In another arrangement, they are carried in a rotating disc and are rotatably mounted therein with gearing to keep them moving parallel to themselves. In the arrangement shown in Fig. 15, three mirrors 44, 45, 46 carried on slightly inclined shafts geared together move into succession into the light beams.