Patent GB-701564-A (GB)
Title: Improvements in or relating to photographic roll film cameras
IPC: G03B1/66
Filed: 1952-04-04
Abstract: 701,564. Photographic roll-film cameras. KODAK. Ltd. April 4, 1952 [April 4, 1951], No. 8626/52. Class 98(1) The camera has film metering means for operation in each direction of the film movement, including a ratchet-wheel carrying an exposure-indicating dial and rotatably mounted in the camera and a spring-controlled pawl device carried by a slide movable to and fro by rotation of the film winding member, the pawl device acting to rotate the ratchet-wheel step by step in one direction or the other according to the direction of rotation of the film winding member until a mutilated part of the ratchet-wheel becomes located at a position at which it permits the pawl device to idle during subsequent movements of the slide effected by continued operation of the film winding member. As shown, the mechanism is incorporated in a camera of the kind described in Specification 701,563 in which a film-winding knob 10 is mounted on a shaft 11 carrying a ratchet-wheel 57. A pawl 63 is normally spring-urged towards ratchet 57 to prevent rotation of the knob in a clockwise direction. A spool of film is placed on shaft 11, and pawl 63 is moved away from ratchet 57 by means of a finger piece 67 protruding from the camera. Knob 10 is then turned clockwise to move the film across the exposure gate into a chamber in which it becomes loosely rolled. A plate 45 is mounted to slide on a plate 46 in the camera by means of pins 47, 48 on plate 46 engaging slots in plate 45. Plate 45 carries a plate 110 with upturned flanges 111, 112 at each end and a slot 115 in the middle. A pin 116 on plate 45 engages slot 115 and is encircled by a spring 117 which presses plate 110 against pins 113 on plate 45. The ratchet 57 has pins 56 which engage a finger 55 of plate 45 which is thereby moved to the left, and, as pin 56 moves past finger 55, is returned by a spring 53 acting on a pin 51 on plate 45. At each reciprocation flange 112 engages a tooth of ratchet-wheel 104 rotatably mounted on a stud 104s on plate 46. The following tooth of the ratchet 104 pivots plate 110 about the pin 113 opposite flange 111, so that on return flange 112 clicks into engagement with the flank of the next tooth. Thus ratchet 104 is turned tooth by tooth, and a disc 100 fast with it also turns, displaying exposure numbers through a window 13 in the top wall 9 of the camera. The numbers decrease until 0 is reached. Flange 112 then encounters a gap 108 in ratchet 104, which is thus not turned while the last part of the film is wound in. Pawl 63 is then allowed to return, and the camera is ready to take photographs. Knob 10 is now turned anticlockwise. One of the pins 56 now moves plate 45 to the right; during this movement the shutter is set. In the return movement in which a spring 52 engages the pin 51 a lug 59 on a lever 60 engages a shoulder 58 on plate 45, holding the plate to form a stop for the next pin 56. In this position a flange 71 on the shutter release 12 is opposite a recess 70 in plate 45, so that the release can be depressed. The shutter action rocks a lever 82 connected to lever 60 so that plate 45 is released and completes its movement to the left. Recess 70 is now out of register with flange 71, so that another exposure cannot be made until the film has been wound. During this movement of plate 45 flange 111 engages ratchet 104 and moves it back one tooth. The numbers seen in window 13 thus indicate the number of exposures made. When all the exposures have been made, flange 111 encounters the gap 108, and a bump on a cam 109, fast with ratchet 104, engages a lug on lever 82, so that lug 59 on lever 60 is held out of engagement with shoulder 58. Thus the end of the film is wound back on to its spool without operation of the ratchet 104 or of the locking mechanism. Specification 689,376 also is referred to.