Patent GB-191008874-A (GB)
Title: Improvements in connection with Photographic Cameras having Exposure Shutters known as Self-closing Focal Plane Shutters.
Inventor: STUART JOHN
IPC: G03B9/34
Filed: 1910-04-12
Granted: 1911-04-12
Abstract: 8874. Stuart, J., and Jochumsen, G. April 12. Shutters, roller-blind. -The shutter is one in which both blinds are wound up together with no slit. For time exposures or for focusing, the lower blind is separately released, the upper blind being released subsequently. For bulb exposures, the trigger is operated to release the lower blind, holding the upper blind until, on letting go, the upper blind is released. For instantaneous exposures, the upper blind is further independently wound according to the slit required and, at the end of the exposure, follows up the lower blind to re - close the aperture. The lower and upper blinds are operated separately from wheels 1, 2, Figs. 1 and 3, which are mounted on the winding - spindle shaft 11. The lower blind 1 is on an outer sleeve 22 which extends to a disk 24. This is rotated by the winding-head 29 by a pin 30 on the head engaging a pin 26 mounted on the plate 24. The plate 25 carrying the pin 26 is mounted bv a pin 54 extending through a slot 55 in the disk 24. The upper-blind wheel 2 is on an inner sleeve 16, and is rotated by a projection 15, Fig. 6, on the wheel 1, which carries with it a pin 14, Fig. 7, of a pawl 13 pivoted on the wheel 2. The shutter is thus wound until a projection 31, Fig. 6, on the wheel, engages under a stop 32, Fig. 2, on the casing, and simultaneously the projection 15 engages behind a sliding bolt 33. The sliding bolts 33, 34 are adapted to engage alternately the wheels 1, 2. A pivoted cross-rod 39 engages between stops 41, 42 on the bolt 33 and presses on a pin 43 of the bolt 34. The rod 39 is controlled by a spring 44 against the action of a weaker spring 45 tending to raise the bolt. The bolt 33 is actuated from the release pin 51 through a lever 50 and a bell-crank lever 46. The bolt 33 can also be moved by a pin 59, Fig. 1, on a slide 57. In focusing and for time exposures, the slide 57 is depressed by sliding a knob 74, thereby releasing the bolt 33 from the wheel 1 and freeing the lower blind. Simultaneously the rod 39 tilts over, and the bolt 34 is raised by the springs 45 to engage a projection 36 on the wheel 2 and retain the upper blind. To release the upper blind, the slide 57 is raised, and the spring 44 pulls the rod 39 and bolts into their normal position. For bulb exposures, the shutter is wound and the release pin 51 is pressed, thereby actuating the lever 50 and bell-crank 46, and lowering the bolt 33. The lower-blind wheel 1 is thus released, and the bolt 33 under the influence of the spring 45 is raised to engage and retain the upper-blind wheel 2 until, on letting go the release pin 51, the bolts return to their normal position, and the bolt 33 disengages from the upper-blind wheel 2. For instantaneous exposures, the bolt 34 is retained in its lower position by a bell-crank lever 61, which engages a pin 63 on the bolt. The lever 61 is tilted by raising the slide 57 into its highest position. The wheel 2 is thus not stopped and the upper blind is free to follow on to close the aperture. For independently winding the upper blind, the sleeve 16 of the wheel 2 is provided with an arm 17, Figs. 3 and 5. When the lower blind is wound to the fullest extent and held by the bolt 34, the pin 54 projecting through the slot 55 rides on the upper surface 56 of the slide 57, and the pin 26 is tilted inwards free from the carrying - pin 30. On further winding of the head 29, the pin 30 engages the arm 17 and continues thus to turn the wheel 2. To adjust the width of the slit and to hold the upper blind when fully wound, a disk 19, Fig. 7, with a ratchet tooth 20 is mounted on an intermediate sleeve 18. The disk 19 is locked to the lowerblind wheel 1 by a pin 69, Fig. 3, on an adjusting-key 70. The pin extends through a hole 68 in an arm 21 of the sleeve 18. The adjusting- key 70 is loosely mounted on the sleeve 16, and is adapted to engage one of a series of notches 71 on the inner surface of the cylindrical piece 27, which is screwed on to the flange 24. The angular position of the disk 19 and ratchet 20 relatively to the lower-blind wheel 1 can thus be adjusted and determines the extent to which the upper blind is further wound before the pawl 13 on the wheel engages the ratchet 20 by which it is held. On actuating the release 51, both blinds rotate together until the lower blind has run down and is stopped by a pin 64, Fig. 6, coming against the stop 32 on the casing. The upper blind is now released by means of an angular lever 66 pivoted at 67 on the wheel 1, which is tilted by the stop 32 and lifts the pin 14, Fig. 7, on the pawl 13, thus disengaging the pawl from the tooth 20. The pin 26, Fig. 1, is replaced in position for re-winding the shutter by a bent spring 25<1>, Fig. 5, which acts on the arm 25. The slide 57 can be moved into its respective positions by a disk 74 with a pin 75 engaging a recess 76 in the slide.