Patent GB-182814-A (GB)
IPC: G03B33/00
Filed: 1922-07-08
Abstract: 182,814. Diernhofer, H. July 9, 1921, [Convention date]. Colour photography.-In a shutter and plate-changing mechanism for cameras employed in the production of part negatives for multi-colour photography, the various times of exposure for the part negatives are all set on adjusting discs prior to exposure, and on releasing the mechanism the exposures and the necessary plate changes between them are made automatically in succession, and after each exposure the adjusting-disc for the next exposure is brought automatically into position to adjust the shutter mechanism for this exposure. In the form shown, the shutter 2, in addition to the usual adjusting- disc 3 carries auxiliary discs 5, 6 which are frictionally mounted on the same spindle 7 as the disc 3, and are each provided with a finger 10, 11 adapted to co-operate with a spring-controlled lever 21 mounted on a pin 20 on a slide 17 movable in a fixed vertical guide 15. The slide 17 carries a stepped cam 23, which turns on a pivot 24, and carries three pins 30 which coact with fixed projections 31, 32 respectively during the downward and upward movements of the slide to produce at each movement a rotation of the cam through one-sixth of a revolution. The stepped surfaces 25 to 29 of the cam are thereby caused to bear in turn against the pivoted lever 21 and incline it stepwise so that, as the slide reciprocates, the arm 21a of the lever moves (1) down past the arm 10, (2) up to rotate the arm 10 to adjust the shutter in accordance with the preliminary setting on the disc 5, (3) down between the arms 10, 11, (4) up to rotate the arm 11 to adjust the shutter in accordance with the preliminary setting of the disc 6, (5) down past the arm 11, and (6) up to the initial position again past the arm 10. During the downward movements, the tensioning-lever 73 of the shutter is depressed by a ledge 16 on the arm 17 to arm the shutter, and on the upward movements, the shutter is released by the engagement of the end of the ledge 16 with a pin 78 on a lever 75 connected by a pull-wire 76 with the release lever 77. The first downward movement of the slide 17 is produced by finger pressure, and the slide is locked by the engagement with the ledge 16 of a claw 34 which, in all subsequent movements, is held clear of the ledge by a catch 38. This movement stresses a spring in a casing 14, and, through a Bowden wire 49, rotates a clockwork control lever 48 anti-clockwise from the position shown in Fig. 1, to bring a pin 50 upon it under a lever 52 co-operating with the clockwork release gear. The first upward movement of the slide 17 is produced by pressing the usual wire release 58, which disengages the claw 34; the spring in the casing 19 then lifts the slide 17 to make the first exposure set on the disc 3, and change the shutter setting. During this movement, the Bowden wire rotates the lever 48 clockwise against the action of a spring 62, and the pin 50 rotates the release lever 52 and starts the clockwork mechanism to effect the necessary change of plates for the next exposure. The rotating clockwork shaft 41 carries with it a lever 64 having pins 63, one of which engages a lug 65 on the lever 48 and turns the lever back again anticlockwise, thus, through the Bowden wire, producing the second downward movement of the slide 17, and stressing the spring in the casing 19. When the lever 64 has completed half a revolution, the clockwork mechanism is automatically locked and the spring in the casing 19 is free to produce the second upward movement of the slide 17 and the exposure of the second plate. The same cycle of changes recurs for the third plate. After the third exposure, the broad end 70 of the lever 64 lifts the clockwork release lever 52 out of the path of the pin 50 on the lever 48, so that the clockwork is not again released ; and the lever 52 is returned into the path of the pin 50 only when the clockwork is rewound. Provision is made to ensure that the change of plates does not occur until each plate has been exposed.