Patent GB-518222-A (GB)
Title: Photographic roll film cameras
IPC: G03B19/04
Filed: 1938-08-12
Abstract: 518,222. Photographic roll - film cameras. VOIGTLANDER & SOHN AKT.-GES., and BAUMGARTNER, W. Aug. 12, 1938, No. 23887. [Class 98 (i)] Relates to roll-film cameras having shutters at the ends of the exposure opening to vary the size of picture and film feeding means which may be selectively set to feed correspondingly long or short sections of film, and consists in a camera in which the mechanism controlling the feed. of film comprises a member moved by the film being fed which operates, through mechanism adapted to be set for different transmission ratios, a movable member which is locked by an arresting element when the required feed movement has occurred, together with means for varying the amount of film feed at each feeding operation immediately following a change in the picture size. This variation is such that the feed of film immediately following a setting from the large to the small size of picture exceeds the normal feed for the small picture by an amount sufficient to move the trailing edge of the preceding large picture out of the exposure aperture, whilst the feed of film immediately following a setting from the small to the large picture size is less than the normal for a large picture to avoid the waste of film which would otherwise occur between the small and large pictures. In the camera shown, the turning of a control disc 62, Fig. 5, causes, through gears 61, 72, 73 the partial rotation of a gear 74, Fig. 3, which through pin-and-slot connections 76, 77 moves two slides 59, 78 in opposite directions. Fingers 58 on these slides engage arms 81 on shutters 11, 12 pivoted at the upper and lower edges of the exposure opening, the movements of the slides closing the shutters to the position shown in dotted lines for small-sized pictures, or allowing them to open under the action of springs to the full-line position for large pictures. The film passes over and rotates a toothed roller 20, on the spindle 24 of which is a gear 23 which rotates, through two alternative gear trains used respectively when taking large and small picures, a measuring disc 28 having a notch 30 in which engages the nose 32 of a lever 31 to lock the mechanism when the correct length of film has been fed. Figs. 4 and 5 show the mechanism adjusted for small pictures, the gear train in use comprising the gears 23, 37, 39, 41 43, 45 and 29. The train employed when taking large pictures, for which the parts are adjusted as shown in Fig. 1, consists of the gears 23, 50, 52, 54, 45 and 29. Spring-opened toothed clutches between the gears 37, 39 and 50, 52 are alternately closed, to put the corresponding train into gear, by cam members 64, 65 on a substantially triangular plate 63 which is mounted on the shaft 60 of the control disc 62 and rotated between the positions shown in Figs. 1 and 2 to cause the depression of either the gear 50 or the gear 37 by the corresponding cam. In order, after setting the camera for small pictures, that the first length of film wound may be sufficient to remove the previous large - sized exposed portion wholly from the exposure aperture, a lost-motion drive is provided by a pin-and-slot connection 44, 48 between the. gears 41, 45, the disc 28 not being driven until the pin has moved the length of the slot. Subsequently, normal lengths of film for the small picture size are wound, the pin 44 being at the other end-of the slot and the drive being transmitted without lost motion. In changing to a large-size picture, the plate 63 is rotated clockwise to the positon shown in Fig. 1, during which operation a pawl 67 pivoted to it runs off a large on to a small diameter segment of a fixed cam 69 and so engages a ratchet wheel 66 secured to the gear 54 which is thus rotated with the plate 63. This gives a lead to the setting of the measuring disc 28, so that the first length of film wound is less than the normal for the large-size picture, thereby avoiding a waste strip of film between the small and large size picture. At the same time the gear 45 rotates the gear 43 in the direction of the arrow y, so bringing the trailing end of the slot 48 again into contact with the pin 44, and thereby again introducing the lost-motion drive above referred to when the camera is re-adjusted for small pictures. To wind off the film backing paper, the disc 62 is adjusted to an intermediate position in which the clutch of neither gear train is engaged. When the film is in position for the first exposure the disc 28, which projects slightly through a slot in the camera wall is turned by hand until it is locked by the lever 31, which also at the same time locks the film delivery spool by means of a tooth 33 engaging a ratchet wheel 15. The shutter-telease and film-wind are interlocked so that they can be performed only alternately. The shutter release comprises a trigger 115 projecting beneath the base board, and movable transversely of it to operate a slide 114 having a pin-and-slot connection to the end of a lever 107 which is pivoted at 108 and engages the shutter release 109. A transverse rockshaft 99 carries arms 101, 102, a spring maintaining the arm 101 in contact with a finger 96 projecting laterally from the lever 31. When the lever 31 is not in locking position, as in Fig. 1, the finger 96 holds the arm 101 in. a position such that the arm 102 is positioned in front of the turned-over upper end of a finger 117 on the slide 114 which is therefore locked and prevents operation of the shutter release. When the film has been advanced the lever 31 turns clockwise to lock the disc 28, and in so doing depresses the arm 101 and raises the arm 102, freeing the slide 114. When the release is operated, the slide moving to the left in Fig. 9, the arm 102 rides up the inclined upper face of the finger 117 until it is turned downwardly behind it by the spring. On the return movement of the slide, the arm 102 is engaged by the lower inclined face of the finger and depressed thereby, causing the arm 101 to move the lever 31 out of locking engagement with the slot in the disc 28. At this moment a masking plate 120, Fig. 12, carried on the disc 28 is moved by a spring 124 to cover the slot 30, so that when the finger 117 releases the arm 101 the nose 32 of the lever 31 cannot enter the slot, and the lever moves only sufficiently to allow the arm 102 to rise and lock the slide 114 of the shutter release. When the film has been wound, the nose 32 engages the edge of the masking plate and moves it to one side, the nose thereafter engaging in the slot, locking the film wind and unlocking the shutter release as above described. In a modification, means are provided for holding the lever 31 out of locking engagement with the disc 28 while the leading and tail ends of the film backing paper are being wound; during these periods a cam which is concentric with the disc 28 is rotated through gears from the gear 23 engages the nose 23 to hold it from the disc 28.