Patent GB-689376-A (GB)
Title: Improvements in or relating to photographic camera shutters
IPC: G03B9/14
Filed: 1951-10-29
Abstract: 689,376. Photographic shutters. KODAK, Ltd. Oct. 29, 1951 [Nov. 24, 1950], No. 25202/51. Class 98 (i). In a setting type shutter comprising a pair of blades which are pivoted on a support and which when the shutter is set occupy positions at which one blade serving as an opening blade covers the shutter aperture while the other blade serving as a closing blade is held clear of said aperture, the blades are retained in these " set " positions by latch elements on a pivotallymounted latch lever which upon operation of a shutter release member is moved initially a sufficient distance to release the opening blade, which thereupon is moved clear of the aperture by spring-action, and thereafter is moved a further distance to release the closing blade which then moves under spring action to end the exposure. As shown, the opening blade 3 is pivoted at 4 on the base-plate 1 and is urged anti-clockwise by a spring 5, while the closing blade 14, pivoted at 23 on the far side of the plate 1 and covering the exposure aperture 2 therein, is urged clockwise by a spring 24, a pin 13 on the blade' 14 extending through an arcuate slot 62 in the plate 1. Fig. 6 shows the shutter at the completion of an exposure but before the release of the trigger 40. When this is released, the lever 33 pivoted at 36 is urged to its normal position with its pin 37 against the inner end of a slot 38 in the plate 1 by a spring 31<SP>1</SP> between a lug 31 on a lever 16 and a flange 32 on the lever 33. To set the shutter, a manually-slidable member carrying a pin 65 is moved to the right and engages a projection 8 on the blade 3 to rotate the latter clockwise. As it closes over the aperture 2, a recess 12 on it engages the pin 13 on the blade 14, which is thereby rotated anti-clockwise to a position in which a pin 22, which is carried on a latching lever 16 pivoted at 17 and urged anti-clockwise by the spring 311 and projects through a slot in the plate 1, has ridden off the curved periphery 30 of the blade 14 into a latch recess 28. On releasing the slide carrying the pin 65, the blade 3 moves slightly anticlockwise so that the lug 10 on it is engaged by the latching finger 15 on the lever 16. On depressing the trigger 40 engaging the flange 32 on the lever 33, the " riser " of a stepped portion 39 of the lever engages a shoulder 20 on the latch lever 16, which is thereby pivoted clockwise, releasing the opening blade 3 which rapidly opens the aperture 2. After the aperture has been open for a major part of the selected exposure time, the continued movement of the blade 3 brings a lug 9 on it against a shoulder 19 on the lever 16, driving it clockwise to release the blade 14, which rotates rapidly to close the aperture. To effect a " bulb " exposure, a knob 70 carrying a pin 71 against which an arm 81 of a lever 80 pivoted at 84<SP>1</SP> on the far side of the plate 1 normally bears is rotated from the " instantaneous " setting 72 to the " bulb " position 73, allowing the lever 80 to be rotated by its spring 82 to move a finger 86 into a position on the opposite side of the path of the lug 29 on the blade 14 to that shown, when the arm 85 on the lever 80 bears against the pin 37 on the release lever 33. On now depressing the trigger 40 after setting the shutter, the .blade 3 is released as before, but simultaneously the finger 86 is moved into the path of the lug 29 on the blade 14, thereby preventing the blade from closing the aperture until the trigger is released, when the lever 33 moves clockwise and returns the lever 80 to its " bulb " rest position.