Patent GB-426915-A (GB)
Title: Improvements relating to film feed mechanism for photographic roll film cameras
IPC: G03B19/04
Filed: 1934-09-06
Abstract: 426,915. Photographic roll - film cameras. FRANKE, P., 32, Wolfenbuttlerstrasse, and HEIDECKE, R., 7, Seesenerstrasse, both in Brunswick, Germany. Sept 6, 1934, No. 25686. [Class 98 (i)] When loading into a camera a film provided with a leader strip, the ridge at the join of the film and leader strip actuates, during the initial winding movement, mechanism to lock the take-up spool or to operate visual means for indicating that the first exposure area of the film is in the focal window. The take-up spool may then be unlocked by hand, and counting mechanism, which has been held inoperative during this initial movement, may be coupled to the film feeding mechanism. The film b with paper tab a joined at 25 is fed from the delivery spool 1 to the take-up spool 2 past the camera window 3. A slide 11 supports upon pillars 13, 14, the counting wheel 15 and the gear wheels 16, 17 respectively, and is urged to the left by a spring 12. When a roll of film is placed in the delivery spool 1, the nose 5 of a lever 6 is raised, displacing the rod 9 out of engagement with the tooth 11<a>. The slide 11 then moves to the left under the action of spring 12 so that the gear wheel 17 is out of gear with the take-up spool. A bell-crank lever 20 is pivoted to the slide 11 and to a rocker 23 with a frictional end, so that the latter is urged by the movement of the slide into engagement with the film. The other end of the rocker 23 is connected by a stud 27 and slot 28 to the shank of a pawl 24 upon which is a stud 26 in the path of the arm 22 of the bellcrank lever. When the take-up spool is rotated and the ridge 25 engages the rocker 23, the latter is actuated drawing down the pawl 24 into engagement with the teeth of the gear wheel 19 of the take-up spool to lock the mechanism. The lever 20 is then rotated by hand, and moves the slide to the right where it is held by the catch 11<a>. The counting wheel 15 is then in gear with the take-up spool, whilst the pawl 24 has been restored to its original freed position by engagement of the arm 22 with the pin 26. The means for rotating the take-up spool comprises a crank 29 attached to a cam 30 with a raised portion 31. The cam is connected by a free wheel device to a toothed wheel 32, so that there is positive engagement in a clockwise direction only. The wheel 32 is connected through gear wheels 33, 34, 35, 36, to a toothed sector 37 having a hooked extension 38 which is adapted to engage with the raised part 31 of the cam 30. The latter also engages a double-armed lever 40 which is held against a fixed abutment 32 by a spring 42. When a fresh section of film is to be moved into position, the crank is rotated until the raised portion 31 of the cam engages the extension 38. In view of the rotation of the sector 37, each successive swing of the crank is shorter than the one before, thus keeping uniform the length of film wound on. Instead of actuating the bell-crank lever 20 by hand, the crank 29 can be used for this purpose by engagement of the cam 30 with the lever 40 with sufficient force to overcome the spring 42.