Patent GB-190425383-A (GB)
Title: Improvements in Photographic Shutters.
Inventor: WRIGHT JOHN STRATTON
Filed: 1904-11-22
Granted: 1905-03-02
Abstract: 25,383. Wright, J. S. Nov. 22. Shutters. - Relates to a photographic shutter, with a roller blind, which may be used for instantaneous or time exposures, and which may be used when the curtain is moving in either direction, up or down. A further object is to provide means for varying the width of the slot in the curtain and for indicating this width. The shutter is an improvement on that described in Specification No. 9572, A.D. 1903. The curtain 21 is made in two parts separated by a slot 24, the two parts being fastened respectively to the rolls 25, 26. The roll 25 consists of a tube 27, to one end of which is fastened a disc 29, which in turn is fastened to the sleeve 30. On the end of this sleeve is an intermittent pinion gear 31 meshing into the intermittent stop gear 32, which has a stop tooth 34 for use in time exposures. Within the tube 27, and fastened to it, is a disc 35 free to rotate upon a spindle 36 journalled in the sleeve 30. A torsional spring 38 has one end fastened to a collar 39 fast on the spindle 36, and the other end to the disc 35. A clutch disc 40 fast on the spindle 36 is provided with recesses 41 adapted to engage a pin 42 carried on the disc 35, and thereby to lock the spindle to the tube 27 when the spindle is drawn toward the right from the position shown in Fig. 4. Fastened to this spindle are the wheels 43<11>, 44, and engaging with the latter is a pawl lever 45 pivoted at 46. The other arm 47 of this lever extends across one end of a pneumatic piston 48, which when forced out releases the ratchetwheel 44. The lower roll 26 is constructed in a similar manner, but with the torsional spring 61 wound in the opposite way. A lever 72 pivoted at 73 carries two stops 74, 75, which are alternately thrown into and out of line with the pneumatic pistons 48,71as the leverisrocked ; at the same time, the forked ends of the lever shown in Fig. 1 cause one spindle to be shifted to the left and the other to the right, thus unlocking one spindle and.locking the other to their respective rolls. The lever 72 is rocked by means of the slide 105, capable of moving up and down on the ways 106. This slide also carries a winding-gear 111 constructed to gear with the wheel 43<11> or the wheel 66<11> according as it is at the top or bottom of the slide. The operation is as follows :-The curtain being wound on the upper roll, the slide 105 is moved down till the wheel 111 gears with the wheel 66<11>, locking the spindle 36 to the roll 21 and releasing the roll 26 from its spindle 59. On the air bulb being pressed, the piston 48, which is free to move, moves and allows the upper roll and spindle to rotate together under the pull of the curtain, which has all the time been exerted by the lower spring, thus winding the curtain on the lower roll. By moving the slide up again, the action may be reversed. To adjust the width of the slot, the curtain is first wound on the upper roll 21, and the position shown in Fig. 4 is attained, with the lower spindle locked to its roll. This lower roll is then rotated, against the action of the upper spring, by means of the screw 66, until the rod 77 under the pressure of the spring 116 enters the hole 76 in the intermittent stop gear 55 and thus locks the roll against rotation. The curtain has then been partially unrolled. The rod 77, which is only permitted to move as above when the slide 134 has been previously drawn down, has a bevelled wheel 125 supporting a slide 123, which is drawn down from the slot 121 by the action of the spring 124 when the rod 77 moves to the right. The fall of the slide 123 permits the clutch slide 60 to be moved to the left, thereby disengaging its projections 81 from depressions in the disc 83, fast to the roll, and at the same time causing the wheel 126 to gear with the wheel 127 of the dial. Upon rotation of the thumb-disc 80, the two tape-wheels 85, 90 are rotated, the latter by aid of the two pinions 86, 88. A piece of tape is fastened to each tape-wheel and passes up through eyes 93,94, respectively, fastened to the upper half of the curtain, and then down, finally terminating at the eyes 96, 97 of the lower curtain. With the aid then of the upper spring 38, the slot may be either increased or decreased by rotating the disc 80, the amount being registered on the dial. The operation for time exposures is as follows :-The slot having been adjusted and the slides 60, 134 replaced, so that the rod 77 no longer locks the lower roll, a lever, carrying a slide 137, is rocked by a cam-plate. This slide is moved across the path of the stop tooth 34 of the intermittent stop gear 32 ; if, then, the slide 105 be moved to its lowest position and the air bulb pressed, the curtain unrolls till stopped by the slide 137 coming in contact with the tooth 34. Finally, on removal of this slide 137 and depression of the bulb again, the curtain is wound entirely upon the lower roll.