Patent GB-617156-A (GB)
Title: Improvements in photographic apparatus
IPC: G03B15/00
Filed: 1945-05-18
Abstract: 617,156. Photographic cameras. RABANIT, P. May 18, 1945, No. 12645. Convention date, Sept. 5, 1944. Addition to 604,681. [A Specification was laid open to inspection under Sect. 91 of the Acts, May 18, 1945.] [Class 98 (i)] In a modification of the apparatus described in the parent Specification, means is provided to interlock the drives of the unexposed and the exposed light-sensitive paper or film strip to prevent the feeding of a second length of film for exposure before the exposed strip has been wound off into the receiver, said means preferably comprising a lever pivoted on the body of the apparatus and having projections engaging cam means on the driving shafts of each crank, whereby after a predetermined number of revolutions of the unexposed film driving shaft its further rotation is arrested, and it is not again rotatable until after the exposed drive has been operated. Fig. 1 shows the apparatus after the strip has been exposed and cut off. On rotating by a crank the shaft 5 anti-clockwise to feed the exposed film into the light-tight receptacle (not shown), the nose of a cam 33 engages the projection 32 on the lever 31 which is pivoted on the body at 29, causing it to rock in a clockwise direction against the action of a spring, thus releasing the radial cam ledge 39 from the projection 38, the lever 31 being retained in its non- engaging position by the hooked end of lever 34. The shaft 3 of the unexposed strip driving mechanism is then rotated anti-clockwise, and the strip intermittently fed and exposed as described in the parent Specification, initial movement of the shaft 3 causing a cam 41 to engage a projection 42 tripping a lever 43 to release the knife 45 which moves back towards the stop 47 opening the film channel. A gear 15 on one of the mutilated feed roller shafts engages a gear 16, the combination having a 3 : 1 step down ratio. As the film is fed, the pin 21 on the lever 22, which is pivoted on the body at 23, follows the contour of the cam 18, thus withdrawing the forward tip of the bell-crank lever 26 pivoted at 25 on the lever 22 so as to engage behind the knife 45. At the end of the fifth exposure the pin 37 on the gear 16 trips the lever 34, thus releasing the lever 31, but allowing the shaft 3 to make one more revolution, after which the shaft is stopped by the projection 38 engaging the radial ledge 39. At the end of the sixth exposure, the pin 21 drops down the cam step 19, allowing the lever 22 to move clockwise, driving, through the lever 26, the knife sharply across to cut the strip and close the feed channel in light-tight manner. The cycle of operations is then repeated. The Specification as open to inspection under Sect. 91, shows in Fig. 5 (Cancelled) the exposed strip driving mechanism immediately prior to operation. On rotating the crank 4 clockwise a cam 54, fast with a gear wheel 53, rotates anti-clockwise, and the projection on the end of the arm 55 of a bell-crank lever pivoted at 56 slides down the sloping cam face, bringing the roller 58 on the other arm of the bell-crank lever into driving contact with the strip. As the gear 53 rotates farther, a pin 61 on an arm 62 follows the outer surface of a cam 59 which is fixed on the shaft of the gear 53, so that the arms 62 and 64 cause the strip to be pushed into the receiver by the foot 66 of the rod 65 after it has passed clear of the rollers 51, 58. When the cam 54 has completed one revolution its step prevents further rotation of the crank 4, and on releasing the crank the cam is returned to its original position by spring means (not shown). This subject-matter does not appear in the Specification as accepted.