Patent GB-709462-A (GB)
Title: Improvements in or relating to photographic roll film cameras
IPC: G03B1/66
Filed: 1952-03-24
Abstract: 709,462. Photographic roll-film cameras. KODAK, Ltd. March 24, 1952 [March 28, 1951], No. 7517/52. Class 98(1) In a camera in which a film is unwound from a supply spool upon rotation in one direction of a film-winding member and is coiled up after crossing the camera exposure aperture into a loose coil and in which exposure of the film is effected between rewinding movements of the film on to the supply spool, a film metering tape is connected at one end to a tape-driving member rotatably mounted on a film-winding shaft for receiving and rotating a film spool, and means controlled by the film in the final part of the rewinding movement thereof release a connection between the tapedriving member and said shaft and hold the connecting means disengaged to permit a final rewinding movement of the film relatively to the metering tape. Preferably the unwinding movement of the film is limited by a latch controlled by the metering tape, and, during rewinding, movement of the film and tape is arrested at the end of every exposure frame fed. As shown, a film winding shaft 25 having flats 26 engaged by a spool having a corresponding apertured flange is rotatable in a journal 35 by a knob 7 and is provided with a ratchet wheel 27 engaged by a pawl on a spring-urged manually releasable lever 29 pivoted in the camera body at 30 so as normally to prevent clockwise rotation. One end of a spring metal tape 18, which extends from a supply chamber 17 to a take-up chamber 21 in which the free end is retained by engagement between a projection 56 on the tape and a shoulder 57 in the chamber, is secured to a sheave 36 freely rotatable on the shaft 25, a friction clutch being arranged to drive the sheave from the shaft and comprising a disc 38 urged by a spring 46 to engage a disc 43 having a downturned lug 44 engaging in a notch 45 in the sheave, both discs 38, 43 being slidably keyed to the shaft 25 by means of the flats 26. A pawl 41 is mounted in a radial slot in the sheave to pivot in a notch therein on a pawl projection 61 and is held in the slot by the outer end 95 of a spring 98 fixed in a groove in the sheave, said spring urging the pawl into latching engagement with the toothed rim of the disc 38 but said pawl initially being held out of engagement with the disc by a lug 53 on a clockwise urged lever 50. By pressing the lever 29 clockwise to release the ratchet 27, the knob 7 may be rotated clockwise to feed the film and the tape into their take-up chambers, the sheave and shaft 25 being connected by the friction clutch. When the film engages the 'arm 55 of the lever 50, this pivots anticlockwise releasing the pawl 41 to re-engage the disc 38, whereafter the tape and film are fed together with a predetermined distance between the leading ends. When all the tape convolutions have unwound from the sheave, a vertical arm 73 of a spring 74 fixed in a groove in the sheave and held in the position shown by the tape convolutions so as normally to move along a circular groove 70 moves outwardly to engage in an eccentric recess in the groove and thereby arrest the tape and film, whereupon the lever 29 is released by the operator to re-engage the ratchet 27. Preparatory to an exposure, the film is wound back on to the spool by anticlockwise rotation of the knob until the tape is arrested by movement of a slidable plate 87 having a tooth 88 engaging in the first aperture 19 in the tape to bring the right-hand end of a slot 89 therein against a stop pin 90. After an exposure has been made, a push button 84 on the camera back is depressed against a return spring 82 to engage a flange 86 on the plate 87 and pivot the latter about the pin 90, disengaging the tooth 88 from the aperture 19 so that a spring 91 returns the plate 87 to the initial position shown, the tooth 88 riding along the tape. The film may then be wound on until the tooth 88 again engages in a further aperture 19 in the tape and arrests it as before. When the last exposure has been made, the film and tape may be wound on continuously, no more apertures being provided in the tape. Prior to or just as the film passes from beneath the end 55 of the lever 50, the tape is finally arrested by the engagement of the projection 56 with the shoulder. 57 in the chamber 21, so that the lever 50 pivots clockwise to its full line position and hence on continued winding of the knob 7 the friction clutch slips and the shaft 25 rotates only the spool to wind up the trailing end of the film. Exposure numbers 118 on the tape may be viewed through a window 119 in the camera back at each arrest of the film during the rewinding operation. To avoid missed and double exposures, the button 84 may be replaced by means interconnected with the shutter release as described and claimed in Specification 709,460.