Patent GB-946559-A (GB)
Title: Photographic roll film camera
IPC: G03B1/66
Filed: 1960-07-04
Abstract: 946,559. Photographic cameras. AGFA A.G. July 4,1960 [July 7, 1959], No. 23361/60. Addition to 800,691. Heading G2A. In a photographic camera for roll film provided with a leading strip of backing paper, being an improvement in or modification of the invention of the parent Specification, a feeler responsive to the difference in penetrability between backing paper and film strip, rotatable by the film in passage thereof and displaceable in a radial plane by the film but not by the backing paper, is in operative connection with a driving pawl pivoted eccentrically thereof, the arrangement being such that when the feeler is displaced by the film the pawl is brought into driving engagement with a ratchet stop wheel of a mechanism both for advancing the film as required for successive film frames and for counting the film frames, and in subsequent movement of the film the driving pawl is operated by rotation of the feeler to turn the said ratchet stop wheel until the next stop position of the film, as defined by said mechanism, is reached. As shown, a camera 1 includes a feeler in the form of a star wheel 6 rotatably mounted at one end of a spring-urged two-armed lever 51 pivoted at 72. The feeler has eccentrically mounted thereon a driving pawl 42 having a tooth 43 for engagement with a ratchet wheel 45 of an exposure counting mechanism. The feeler is in a position to marginally engage the film or paper leader after its passage through the exposure aperture defined by a frame 3. A take-up spool 70 and ratchet wheel 69 are connected through a oneway coupling (not shown) to a quick feed lever 71. On opening a rear door 2 of the camera, a lever 64 having a feeler arm 65 is turned about its pivot 67 by its spring 66 and by means of the coupling 62, 74,pivots a feed lock lever 60 in the direction 76 against its spring 63. As a result, a tooth 68 of this lever 60 is removed from the ratchet wheel 69 (thereby freeing the feed mechanism) and a second tooth 61 of this lever is removed from the ratchet wheel 45. At the same time, the lever 60 raises a latch lever 54 by means of a pin 57 thereon and thereby releases end 53 of the lever 51 for pivotal movement under its spring 55 in the direction 77. As well as moving the feeler 6 towards the rear of the camera, by means of a guide lever 50 co-operating with a guide surface 44 on the pawl 42, this movement of the lever 51 results in removal from the ratchet wheel 45 of the tooth 43. The ratchet wheel 45 and counting mechanism are thus freed to return to their rest positions under loading of a spring 49. After inserting a film and closing the door 2 the feeler wheel 6 penetrates the paper backing and the counting mechanism thus remains inoperative whilst the leader is being wound up. When the leading end of the film proper arrives at the feeler 6, the feeler is displaced about its pivot 72 whereby the pawl 42 is able to drivingly engage with the ratchet wheel 45. At the same time the latch lever 54 drops down behind the end 53 to reliably maintain this position throughout exposure of the whole film. Also, on closing of the door 2, the lever 60 was released by the lever 64 and under loading of its spring 63 engaged with its two teeth 68 and 61 the ratchet wheels 69 and 45 respectively. Sequence of events when making an exposure is as follows. On actuating a shutter release button 73, the lever 60 is pivoted clockwise in known manner whereby the teeth 68 and 61 are withdrawn from their respective notches. Immediate return of tooth 61 into its notch (as at 46) is prevented by a known type of spring disc (not shown) having the property of slightly displacing the ratchet wheel 45 in a forward direction after its release. The feed lock is therefore rendered inoperative and -the film may be advanced by operating the lever 71. After two rotations of the wheel 6 and thus also two advances of the wheel 45 (the tooth 61 co-operates with the wheel 45 during these advances to prevent its return to its set position) a further notch 46 registers with the tooth 61 and the lever 60 is able to return to the position in which it locks both the film feed and the counting mechanism.