Patent GB-770634-A (GB)
Title: Improvements in and relating to photographic cameras
Inventor: WILLIAMSON STUART
IPC: G03B15/00
Filed: 1953-06-03
Abstract: 770,634. Photographic cameras. WILLIAMSON MANUFACTURING CO., Ltd. June 3, 1954 [June 3, 1953], No. 15359/53. Class 98(1) A roll film camera includes means for clamping the film in the appropriate form over the whole of its area on which the image falls and means, including a cam making one cycle of movement per exposure cycle and acting through an adjustable ratio linkage for moving the clamping means with the film as a whole during exposure by an amount and at a speed which will substantially compensate for the movement of the image during exposure due to relative movement between the camera and object. In one form, as applied to an aircraft camera, the magazine shown in Fig. 1 and containing film spools and pressure plate is secured by screws 22 to a gearbox as shown in Fig. 3 containing the glass plate, not shown, to which the film is clamped by the pressure plate. A pivoted lever 39 carries a roller 41 engaging a slot in a carriage in which the glass plate is mounted, whereby pivoting of the lever moves the glass plate in its own plane. The lever is coupled by a link 43 to a pivoted lever 45 carrying a follower 46 for a cam 26 on a shaft 24 rotated by a motor 23. The point of attachment of the link 43 is movable along the lever 45, in accordance with the conditions of exposure by a leadscrew, not shown, actuated by a motor 48 through gearing 49. The motor 48 is energized from a remote point, its movement being controlled by a limit switch 51 itself controlled by a remotely operated step-by-step motor 52 driving through gearing 50. To take account of changes in camera constants due, for example, to lens changes the link 43 is attached to the lever 39 through a dovetail slide movable along the lever and secured in a selected position thereon by a set-screw engaging one of a number of holes in the lever. The shaft 24 also carries a cam 25 which, through a follower 27, actuates a plunger 28 in line with a plunger 29 in the magazine to lift the pressure plate when required. The pressure plate 14 is carried, at points near its four corners by links 16 pivoted to pairs of bell cranks interconnected by shafts 18 and acted on by springs 34. Springs about the pivots of the links 16 urge the pressure plate towards one end of its travel. These springs are stressed as the pressure plate and film are moved by the glass plate and return the pressure plate to its initial position when it is lifted by the plunger 29. This acts on a bell crank lever 31 on the shaft 18 the other arm of the lever being pivoted to a link 32 pivoted to a similar arm on the other shaft 18. This link also has pin and slot engagement with levers 35 pivoted at 36 and carrying the anchorages of the springs 34. This arrangement prevents the pressure of the plate 14 rising unduly as it is lifted. The plate may be lifted for film threading, independently of the plunger 29, by a pivoted handle 77 actuating a link 78 coupled to the bell crank 31. In the film threading position the link is held by a sprng 79 with a notch 81 engaging a plate 82. When the magazine cover is in position a pin thereon engages the inclined end 83 of the link 78 to prevent the notch engaging the plate. . The film from the feed spool 56 passes round guide rollers 61, 62 and a measuring roller 66 to the exposure position. The roller 62 is carried on spring loaded arms 63 on a shaft 64 and forms a loop containing enough film for each feed. When the film is fed by rotation of the take-up spool 57 by the motor 58 the loop shortens and a roller 69 on an arm 68 on the shaft 64 engages the operating arm 71 of a brake 72 to allow the feed spool to be rotated by the 'film tension. To allow for the film movement during exposure the roller 67 is carried on arms 74 acted on by springs 75. The movement of the arms to the left in Fig. 1, under the action of film tension is limited by an adjustable stop 76. These features form the subject-matter of Specification 770,635. Specification 654,233 also is referred to.