Patent GB-727437-A (GB)
Title: Improvements in or relating to photographic roll film cameras
IPC: G03B1/66
Filed: 1953-01-08
Abstract: 727,437. Photographic roll film cameras. KODAK, Ltd. Jan. 8, 1953 [Jan. 8, 1952], No. 612/53. Class 98 (1). The camera includes a manually-operable film winding shaft for receiving and rotating a spool of film; a peripherally notched disc forming part of a film metering and/or exposure counting mechanism, another part of which mechanism comprises an indexing lever slidably and pivotally mounted in the camera and having a driving element for successively engaging the notches of the notched disc; a projection extending radially of and movable with the film winding shaft for engaging one end of the indexing lever, whereby upon rotation of the film winding shaft to move the film across an exposure aperture of the camera, the lever executes a limited sliding movement in one direction and causes the notched disc to be indexed by the driving element; and a manually operable shutter releasing member which is operable, after such indexing movement, to pivot the indexing lever so as to release the driving element from the notch engaged thereby and to remove the said end of the lever from the radial projection, whereupon the lever is spring- urged in the opposite direction so as to engage the driving element with the succeeding notch in the notched disc and to position the said end of the lever into the path of the radial projection in readiness for a further film winding operation, said indexing lever simultaneously moving into locking engagement with the shutter release member to prevent a successive shutter release movement thereof prior to a further film winding operation which releases the indexing lever from interlocking engagement with the shutter releasing member. As shown, in a camera in which the film is unwound from a supply spool and pushed through the camera gate by rotation of the supply knob 4 to a take-up chamber in which it coils loosely and which it is fed back in frame lengths for exposure, the knob 4 is normally locked against unwinding movement by a ratchet-engaging pawl 45 which is manually released for unwinding. As the film is unwound it engages the tail 40 of a lever 82 which is secured on a pin 41 capable of pivotal and radial movement in a bearing in the body under action of a spring 43 and which when there is no film in the gate lies against a stop pin 37 so that the nose 81 thereof bears against the film. When the nose 81 engages in a stop perforation in the film, an arm of a lever 42 fixed to the lever 82 strikes a lug 50<SP>1</SP> on the pawl 45 so that the knob 4 is arrested. Simultaneously a notch 91 in lever 42 moves out of the path of a pin 37 on a notched metering disc or wheel 39 carrying an exposure counter dial 19 (Fig. 2, not shown), and the springy end 85 of the lever 42 moves clear of a lug 38 on the notched wheel 39 which due to a one-way spring brake can move only anticlockwise so that the disc may be rotated during film-rewinding, and the arm 142 of lever 42 moves away from a lug 35 on a lever 27 slidably and pivotally mounted on a pin 27<SP>1</SP> and urged towards the left by a spring 28. On rotating the knob 4 anticlockwise, the film cams the nose 81 anticlockwise out of the stop perforation in the film, also moving the pivot 41 inwardly whereupon the spring end 85 of the lever 42 engages the pin 38 on the notched wheel 39 to turn this slightly anticlockwise so that the long projection 19<SP>1</SP> passes clear of a lug 31 on the lever 27 and the lug enters the notch 19<SP>n</SP> simultaneously with the nose 34 of the lever 27 entering the path of lugs 96<SP>1</SP>, 96<SP>2</SP> on a disc 95 on the winding shaft. Continued rotation of the knob causes the lug 96<SP>1</SP> to move the lever 27 to the right and so to disengage the edge 155 on it from a notch 154 in the plunger trigger 53 to free this for operation while also moving the wheel 39 so that the exposure counter dial 19 indicates the first exposure. The trigger is now depressed to make the first exposure and in so doing a bevel on the trigger cams the lever 27 outwardly so that the lug 31 on the lever leaves the first notch 19<SP>n</SP> in the wheel 39 and the lever is moved to the left so that its nose passes behind the lug 96<SP>1</SP> which previously drove it into the path of the lug 96<SP>2</SP>. In so doing, the lug 31 engages in the next notch and the edge 155 on the lever moves into the recess 154 in the trigger to lock it, so that the film wind knob must next be rotated. Such action causes the lug 96<SP>2</SP> to drive the lever 27 to the right rotating the wheel 39 and counter dial and releasing the trigger lock so that a further exposure may be made. Except when the film has been wound after an exposure, the operator is warned that a further exposure cannot be made by an unobscured recess beneath the field of the front lens of a view finder which is occupied by a lug 30 on the lever 27 after winding. When the twentieth and last exposure has been made, the lever 27 again locks the shutter trigger but is held clear of the lugs 961, 96<SP>2</SP> by its lug 31 resting on the long projection 19<SP>1</SP> so that the light-excluding leader strip may be wound back on to the spool without interruption, a spring arm 200 on the lever 27 engaging a lug 219 on the counter dial to prevent clockwise movement of the dial and wheel 39. As the film passes from under the tail 40 of lever 82, the spring arm 85 moves back over the lug 38 on the notched wheel 39 which thereby is locked against anticlockwise movement by engagement of the notch 91 in the lever 42 with the pin 37.