Patent GB-772441-A (GB)
Title: Improvements in and relating to photographic flat-film changing mechanism
IPC: G03B17/34
Filed: 1953-11-30
Abstract: 772,441. Photographic cameras; projectors. STRINGER, H. B., WILLIAMSON, S., and WILLIAMSON MANUFACTURING CO., Ltd Nov. 30, 1954 [Nov. 30, 1953], No. 33265/53. Classes 97(1) and 98(1) In a magazine and film-changing mechanism for flat cut films, the films are arranged in a stack, taken in turn from one end of the stack. flexed through 90 degrees, carried parallel with one side of the stack, then flexed back through 90 degrees to the other end of the stack, the film path including a position where the film may be exposed or projected. This position may be either at one end of the stack or at the side of the stack perpendicular to the plane of the films in the stack. Figs. 1 and 3 show film changing mechanism for a camera (Fig. 3 being a sectional view of Fig. 1). The films are stacked on a plate 23 and fill the space between the catches 25 and an idle roller 24, the space being made up if necessary by packing material 26. The film-change is effected by one rotation of the wheel 28 which is driven from the motor 29 by gears 31, 32, sprocket 33 and chain 34. The motor is started by an impulse from a remote control switch which is in parallel with a micro-switch 37 (initially open) and as soon as the wheel 28 begins to rotate, the pin 35 rides off lever 36 and closes the micro-switch 37 so that the motor continues to operate until the pin 35 again strikes lever 36 and opens microswitch 37. At the end of each cycle there will be a film in between guides 44, 45 in the focal plane of lens 14 and this will be exposed by a focal plane shutter 16 on rollers 17. 18. When the motor operates, the chain 34 drives roller 18 by sprocket 38 and rewinds the blinds, and the chain 34 drives also rollers 41, 57 by. means of sprockets 39, 56. The exposed film is thus drawn by the left-hand roller 41 (which is fitted with rubber tyres 42), round guides 43 into the nip of rollers 55, 57 which pass it up to the pressure plate 58 held on lever 59 pivoted at 61. By this time the pin 64 on wheel 28 is at the right-hand end of a slot 63 in an arm 62 connected to the pressure plate and the latter is thus pulled forward to force the exposed film past the catches 25 on to the end of the stack. Soon after the motor is started, and while the exposed film is being removed from the exposure gate, the pin 35 on wheel 28 strikes a plate 46 on a toothed sector 47 which rotates against the action of a spring 53 and turns a roller 52 fixed to the same shaft as ratchet 51 by means of a pinion 49 and pawl. This feeds the end film from the stack through guides 54. 43 until it is taken by the rotating right-hand roller 41 into the exposure plane 44, 45. As soon as the film enters the nip of the lefthand roller 41, the wheel 28 has completed one revolution and the motor is stopped by micro-switch 37. Before this as soon as pin 35 has ridden off plate 46, the latter returns to its initial position determined by stop 65, but roller 52 is not rotated due to the pawl and ratchet connection. In the apparatus shown in Figs. 4 and 6 the films are provided with holes in their four corners and are fed by pawls and claws. As before they are stacked on plate 69 and changed during one rotation of wheel 71. This wheel, which with the associated mechanism is duplicated on both sides of the apparatus, is rotated by pinions 78 driven by a motor 75. As before, the motor is controlled by a remote control and a micro-switch 74 operated by a pin 72. Fig. 4 shows the parts in their initial position with an exposed film in between guides 93 (Fig. 6) and claws 89 which are attached to arms 91 engaging the rear holes in the exposed film. The arms 91 are engaged by two pins 92 diametrically opposed so that they are swung across against the action of springs (not shown) twice per revolution of the wheel 71. During the first such swing the claws 89 remove the exposed film pushing it round guides 95 until the leading holes of the film engage claws 96 on the pressure plate 97 At the same time an unexposed film is fed from the end of the stack by pawls (not shown) attached to a cross-member which joins arms 81 at 80. The arms 81 are given a downward pull by arms 82 which carry rollers 84 and are operated on by the cam 85 in the first part of the revolution of wheel 71. The film is thus fed round guides 88 until its leading holes are in a position to be engaged by claws 89 when they return from removing the exposed film from the guides 93. The second movement of arms 91 then draws the film into the exposure gate 93 and the claws 87 return to engage the rear, holes ready for the next change cycle. Also during the second part of the film feed movement the large part of cam 85 operates on a roller 99 which pivots levers 90 and. via links 101 and 98, raises the pressure plate 97 carrying the exposed film and .presses it on the end of. the stack behind the catches 103.