GB190108353A - Improvements in or relating to Photographic Shutters - Google Patents

Abstract

8353. Boult, A. J., [Bausch & Lomb Optical Co.]. April 23. Shutters.-The shutter, which may be operated by a trigger, or pneumatically, is enclosed in a casing formed of a front 1 and a back 3 attached to or formed integral with a circumferential ring 2, Fig. 8. Within the casing is a partition 4, on which the shutter and fittings are mounted. The shutter, which preferably consists of perforated leaves 26 pivoted at 27 to the rear of the partition 4, is actuated by pins 29 on a lever or arm 22 pivoted to the front of the partition, the pins passing through a slot in the partition and engaging with projections on the leaves. The lever 22 is lifted and lowered to open and close the shutter by means of a pawl 13 pivoted on a revolving ring 11 suitably mounted and guided on the partition, the pawl having an inclined inturned edge at the front, which, when the ring is rotated to effect an exposure, by means of a spring 16 connected with the pawl and with an adjusting-device 18, pivoted to the partition, engages with a pin 21 on the lever 22 and thus lifts it, the lever again falling under the action of a spring when the inclined edge of the pawl has passed the pin. On rotating the ring in the reverse direction to set the shutter, the pin engages with the inclined edge and lifts tne pawl. The ring is rotated to set the shutter by a pivoted device 38 having an actuating-arm or trigger 40, one edge 41 of the device serving to engage with a pin 42 on the ring, thus rotating it when the trigger is lifted, and a projection 32 on a spring-pivoted catch lever 33 engages with a shoulder 31 on the ring to hold the shutter in the set position. The ring may be released, to effect an exposure, by moving the trigger downwards when the surface 37 of the device 38 engages with the end of the lever 33, or the lever may be operated by actuating a plunger 35 pneumatically. To effect an instantaneous exposure, the pivoted retaining spring levers 45, 46, having shoulders or stops 48, 49, must be moved aside from a projection 30 on the ring, this movement being made by rotating the device 18 by means of a cam slide, the device 18 having cams 51, 52, by which one or both of the levers 45, 46 are actuated. The shoulder 48, or that and the shoulder 49 (one being a little in advance of the other), are allowed to remain in the path of the projection 30 for time exposures, the levers 45 and 46 being afterwards moved aside by the catch lever 33.