Patent GB-689984-A (GB)
Title: Improvements in or relating to roll film photographic cameras
IPC: G03B17/42
Filed: 1950-09-29
Abstract: 689,984. Photographic roll film cameras. KODAK, Ltd. Sept. 29, 1950 [Sept. 30, 1949], No. 23923/50. Class 98 (i). A roll film camera having a film measuring roller is provided with locking mechanism between a film winding spindle and a slidably mounted shutter release plunger, said mechanism including a pair of levers mounted for rocking movement on a common axis, one of said levers being movable, at the end of a predetermined film winding operation, by a member rotatable with the film measuring roller into locking engagement with a ratchet wheel fixed to the film winding spindle, and the other of said levers being moved against spring action by another member rotatable with the film measuring roller into a position at which at the end of said film-winding movement it is held tensioned by a displaceable stop member positioned in the path of movement of the slidable release plunger, which upon being operated displaces the stop member from the tensioned lever, whereupon the tensioned lever is returned under spring action and causes the return of the other lever to a position at which at least one of them prevents a further release operation of the plunger until said levers are again moved to their respective ratchetengaging and tensioned positions at the end of a further film winding operation. As shown, on rotating clockwise the take-up spool shaft 12 which is provided with a reverse winding prevention ratchet wheel 17 engaged by a pawl 18, the film drives a sprocket 14 integral with a film metering roller carrying a cam 20 on which is arranged a pin 36. This pin strikes a lever 29 pivoted at 23 and moves it anticlockwise, tensioning its return spring 30 and moving the end 38 of the lever out of the path of the shutter operating plunger 21, the end of a springy member 33, which member tends to move towards the guide 45, moving downwardly so that its edge 39 is in the same plane as the lever end 38. When the pin 36 moves clear of the lever 29, the latter moves clockwise and the end 38 engages the edge 39 of the member 33 to press this member against the guide 41 when it holds the lever 29 with its spring 30 tensioned. Continued winding of the film brings a step 25. on the cam 20 into register with a claw 24 on a lever 22 pivoted coaxially with the lever 29 so that the lever 22 moves anticlockwise under its spring 42, and moves its end 50 clear of the plunger 21 and a pawl 26 to latch a ratchet wheel 16 on the takeup spool shaft 12, thereby preventing further winding. To make an exposure, the plunger 21 is caused to move upwardly carrying with it the end 35 of the springy member 33 which snaps over the lever 29 which bears against the plunger 21 until this is released and returns to its rest position freeing the lever 29. The lever is then moved clockwise by its tensioned spring 30 and a lug 48 on the lever carries the lever 22 with it so that the ends 39, 50 of the two levers block the path of the plunger and prevent a second exposure while the lever 22 also releases the film wind ratchet 16. If it is desired to make a double exposure on a single film frame, a finger piece 51 on one arm of the lever 29 is moved to the left, moving the ends 38, 50 out of the path of the plunger in the same way as the pin 36 does. For re-winding, a finger piece 53 is moved to the right so that the clockwise-urged pawl 18 engaging a ratchet wheel 17 on the spool shaft 12 is moved anti. clockwise freeing the wheel, and a lug 54 on the pawl arm engages an arm 55 on the lever 22 to disengage the pawl 26 from the ratchet wheel 16.