Patent GB-603993-A (GB)
Title: Improvements in or relating to photographic cameras
IPC: G03B39/04
Filed: 1945-11-20
Abstract: 603,993. Photographic cameras. LUCK, G. A. Nov. 20, 1945, No. 31176. [Class 98 (i)] A camera in which the film is exposed by wrapping it around a drum and continuously rotating the drum past a shutter-controlled aperture has supply and take-up spools mounted within the drum and adapted to rotate both with and relatively to the drum, and means for winding the film without stopping the drum from rotating. As shown, the camera comprises a drum 1 mounted on a driven shaft 2 within alight-tight casing 6, and a shutter 8 mounted within a lens tube 7. The film is led from the supply spool 9 over a sprocket 12 and around the drum via exit and entry slots 10, beneath a jockey pulley 13 and back to the opposite side of the sprocket 12 and thence to the take-up spool 11. On the drum shaft 2 is freely mounted a gear wheel 14 constantly in mesh with a gear 15 on the spindle of the take-up spool, and adjacent to the gear 14 is a clutch gear 16 spring connected to, and hence capable of only limited rotation on, an arm 17 pivoted on the standard 3. To wind on the film the solenoid 19 is energized attracting the arm 17 against the action of a spring 18 and so bringing the gear 16 into mesh with the gear 14. When the spring connecting the gear 16 to the arm 17 tightens the gears 14 and 15 are stopped and the take-up spool driven round relatively to the drum 1. The complete sequence of the exposure and film winding operations is as follows: On closing the self-opening switch 36, the contacts 31 being closed, the solenoid 33 is energized closing contacts 35 and the hold-on contacts 34. As a timing cam 24 on the drum shaft closes contacts 20, solenoid 32 is energized opening the shutter, and solenoid 29 is energized closing hold-on contacts 30, opening contacts 31, and closing contacts 31a. After an interval of somewhat less than one revolution of the shaft 2 a second timing cam 24 opens contacts 21 de-energizing the solenoid 33 which causes the opening of contacts 35 which in turn de-energizes the solenoids 32, 29, closing the shutters and opening contacts 30, 31a and closing contacts 30. Just before the contacts 31a open, a third timing cam 24 closes contact 22 energizing the solenoid 19, which starts the film winding, said operation itself causing a cam 26 to close hold-on contacts 25, the cam being mounted on the spindle of a gear 27 meshing with a gear 28 on the spindle of the sprocket 12 which is rotated by the film. The ratio between gears 27 and 28 is such that when a length of film equal to that of the portion of the drum circumference between the slots 10 has been wound on the cam 26 has made one complete revolution and allows the contacts 25 to open, stopping the film feed. The cycle of operations is then complete and the start of a fresh cycle awaits the actuation of the push button 36. When the film is completely exposed the light tight shield is removed and the spools, which are of the daylight loading type, changed. To compensate continuously for the mass of the spools and the film, an equal mass 1a is mounted so as to be adjustable by a lead screw geared to the take-up spool, whereby the centre of gravity of the spools and counter-balancing mass is maintained at the centre of rotation of the drum. If desired, the spools may be mounted axially in the drum when the compensating mass is not required.