Patent GB-268748-A (GB)
Title: Improvements in or relating to motion picture apparatus
IPC: G03B41/06
Filed: 1927-03-14
Abstract: 268,748. Lysle, E. H. April 2, 1926. [Convention date]. Kinematograph apparatus.-In continuous-feed apparatus having no shutter, optical compensation for the film movement is effected by a series of units, each comprising two reflecting surfaces fixed in relation to one another; the units are moved in a direction having components both in and normal to the direction of the film movement. As shown in vertical section in Fig. 1, and in horizontal section in Fig. 2, prisms 27, having two reflecting surfaces at right angles to one another, are carried by an endless chain so arranged and driven that the prisms move horizontally beneath the film gate 57 in a direction oblique to that of the film. A prism 70 is provided behind the lens 69, and, with each of the prisms 27 successively, reflects the light beam so that its axis takes the path indicated by the lines 71 - - 74. The line of intersection of the reflecting faces of each operative prism 27 is perpendicular to the direction of feed of the film, and the component of the velocity of the prisms in the direction of feed is half the velocity of feed so that the part 74 of the axis of the beam is caused to travel at the same velocity as the film. The dimensions and direction of movement of the prisms 27 are such that, when the part 74 of the axis of the beam has been moved by one of the prisms through the depth of one film image, it is received by the next prism and assumes its original position; the prism now operative again moves the part 74 through the depths of a film image, and so on. When the apparatus is used as a projector, each image on the screen becomes progressively replaced by the next, the line of division travelling laterally across the image area in correspondence with the travel of the adjacent edges of successive prisms across the film. The gate aperture 66 in the plate 57, Fig. 13. is shaped as a rhomboid of such size as to accommodate complementary parts of successive images at all stages of the film movement. The plate 57 is provided with slotted lugs 58, and is drawn upwards by springs 62, Fig. 1, so that shoulders 64 on the lugs engage stop pins 65; the film 54 may thus travel freelv between the plate and the rollers 55, 56, the shafts of which pass through the slots in the lugs. The plate 57 may also be provided with guideways 91, Fig. 13, through which-travels an endless belt 9-2 having substantially rectangular openings 94, one of which is caused to travel across each image area of the film during the time the film moves an image depth. The dimension of the openings 94 in the lateral direction of the film mav be the same as the width of an image, or may be chosen in accordance with the length of exposure desired when taking photographs, and a series of belts with openings of different widths may be provided for alternative use in the apparatus. The openings may be provided with colour screens for use both in taking and projecting images in natural colours. The mechanism of the apparatus may be driven by a handle 33 through bevel gears 28, 29. The shaft 8 of the wheel 28 carries driving gears 9 for the endless chain of prisms, and a spiral gear 35 meshing with a spiral gear 40 on a vertical shaft 39 driving film sprockets 52 through gears 49, 50. The chain of prisms is carried at its ends by idler wheels 16, 16<1>, 17. 17<1>. Toothed gear mechanism (not shown) is described, whereby the gear 35 mav also drive the endless belt 92. The film is illuminated, when the apparatus is used as a projector, bv light through an opening 77 reflected on to it by a mirror 80. The prisms 27 may have reflecting surfaces making greater or smaller angles than 90‹ with each other, the planes of movement of the prisms and film being not parallel to one another, and the prism 70 being dispensed with.