Patent GB-637508-A (GB)
Title: Improvements in or relating to cinematographic projection apparatus
IPC: G03B21/40
Filed: 1946-07-31
Abstract: 637,508. Kinematograph apparatus. MOLLIER, E. N. July 31, 1946, No. 22783. Convention date, Aug. 10, 1945. [Classes 97 (i) and 98 (ii)] A kinematograph projector whereby a picture, disposed in one of two rows on a film and spaced from a picture in the other row by a known number of film frames, is projected immediately after the picture in the other row, comprises a film guiding channel with two exposure apertures therein, each positioned for registry with the pictures in one row and spaced apart by a distance one film frame less than said known number of film frames, sprocket rollers positioned one at each end of the channel and rotated alternatively and intermittently in one or other of two opposite directions so that one picture is held in projection position while the next picture to be projected is being moved into projection position, a film tensioning roller which is spring-urged through an opening between said apertures to form a loop in the film when one sprocket roller is stationary and means for illuminating the picture in either row which is registered with the exposure aperture corresponding thereto and for stopping gradually the illumination of the picture which is so registered, while gradually increasing the illumination of the picture which is next to be projected. In the form shown, the projector includes a platform 3, Figs. 2 and 6, to which is hinged a gate 10 having two spaced apertures which, when the gate is closed, register with the apertures 2a, 2b in a channel 2 in the platform. The spacing between apertures 2a, 2b is equal to five frames of a film 1 which is fed through the channel by sprocket rollers 4, 5. Each sprocket roller is driven by a Maltese cross operated by a stud 50 or 49, Fig. 3, on members 23, 20 which are rotated continuously in one direction or the other by a handle 17 and a chain drive. Between the apertures 2a, 2b an opening 22 is provided in the channel and a spring- tensioned roller 6 is mounted to pass therethrough. Thus, when the picture which is being projected is registered with aperture 2b, sprocket roller 5 is being rotated to move the picture in the other row which is next to be projected into register with aperture 2a and roller 6 forms a loop in the film until roller 4 starts to rotate. Registering with the apertures in the hinged gate 10 and carried by said gate are separate projection lens and mirror arrangements as shown at 41, 42 in Fig. 6 for one arrangement. Each aperture 2a or 2b is provided with a separate illuminating means, one of which is shown in Fig. 6 and comprises a lamp 35, light from which passes through a condenser 36 and a condenser and mirror arrangement 38, 39 and 40 and on to the picture registering with the corresponding aperture. The condenser 36 of each illuminating arrangement forms an image of the light source corresponding thereto at a window 37 or 37a, Fig. 5, and adjacent each window is positioned one of two interconnected shutters. One shutter comprises pivoted plates 26, 27 interconnected by a link 59 and the other shutter comprises pivoted plates 28, 29 interconnected by a link 33 and of which plate 28 is urged in an anti-clockwise direction by a spring 60. The plates 27 and 28 are interconnected by a link 34 and the shutters are actuated by means of a cam 24 on the axis of handle 17 and a rod 32 so that one shutter is opening at the same time as the other is closing. Hence, the illumination of the picture which is being projected is gradually decreased as the illumination of the picture next to be projected is gradually increased. The film 1 is threaded through the channel with the gate 10 open and a hole in the film is engaged with a locating lug 7, Fig. 2, riveted on a spring 8 secured to the platform. When the gate is closed, a part thereof contacts another lug 9 on the spring and this moves the lug 7 out of engagement with the hole in the film. Premature movement of the film after threading is prevented by an arrangement of levers.