Patent GB-267125-A (GB)
Title: Improvements in or relating to continuous-feed cinematograph apparatus
IPC: G03B41/10
Filed: 1927-03-01
Abstract: 267,125. Soc. des Etablissements Gaumont. March 4, 1926. [Convention date]. Kinematograph apparatus. - Continuous-feed cameras or projectors are provided with two objectives, with two reflectors which reciprocate before the gate to divert the projection beam alternately upwards and downwards so that successive film images are projected through different objectives, and with two reflectors which direct the diverted beams through the objectives and are rocked to compensate optically for the film movement; means for adjusting the movements of the compensating prisms in accordance with the pitch of the film, for centering the film, and for adjusting the registration of the projected images are provided. As shown in Figs. 1 and 2, the film is fed by a sprocket 1 through the gate 2 of a projector, and prisms 4, 3 are placed before the gate to reflect the beam alternately to prisms 5, 6 behind objectives 7, 8. The prisms 3, 4 are reciprocated horizontally across the gate aperture by a lever which is pivoted at O<2>, is linked at B<2> to the prism carrier, and is moved by a link connected to it at C<2> and to a crank which is rotated by bevel gearing from the driving shaft O<4>. The prisms 5, 6 are rocked about axles O, O<1> by vertical arms connected, as shown in Fig. 11, by links to pivots F, F<1> on levers A B, A<1> B<1> carrying rollers riding on a cam C on the shaft O<4>. The levers are connected bv links M<1> K, M<2> K<2> to fixed pivots M'. M<2>, and their ends slide in sleeves 34, 35 pivoted in forks 38, 39, so as to obtain substantially vertical movements of the rollers on the cam. The forks 38, 39 are carried by a member 36 which is movable to and from the cam, so as to adjust the movement of the prisms in accordance with the pitch of the film, by a wedge member 42 adjusted in position by a unit 47. The gate has a vertical height somewhat greater than that of two film images, and the visible projection of parasitic images is prevented by the provision of a rotating glass disc having an opaque covering arranged to form clear tracks 32, and of a dark border round the projection screen. The shaft O<5> of the sprocket 1 is driven from the shaft O<4> by gears 11, 12, Fig. 11, the gear 12 being loose on the shaft O<5>, and being secured to a bevel wheel 14 forming part of a differential gear of which the planet pinions 15, 16 are carried by a spindle secured to the shaft O<5>. Film-centring is effected by rotating the normally fixed bevel wheel 13 of the differential gear by means of a knob 29 on the shaft of a worm 30 gearing with a worm wheel 31 connected to the wheel 13. Registration of the images projected by the two objectives is effected approximately by means of a right and left hand screw connection in one of the vertical arms operating the compensating prisms, and more accurately by adjusting the positions of diverging lens elements in front of the objectives. Means for moving such elements vertically, and for moving them to right or left about a pivot above, and parallel to, the optical axis, are described.