Patent GB-652607-A (GB)
Title: Improvements in or relating to focal plane shutters
IPC: G03B9/34
Filed: 1947-07-30
Abstract: 652,607. Roller-blind shutters. KODAK, Ltd. July 30, 1947, No. 20684. Convention date, July 30, 1946. [Class 98 (i)] Each of the two co-axial rollers on to which the two curtains are adapted to be wound against the action of spring rollers is provided with a gear, these gears are interconnected by at least two movably mounted intermeshing gears, means operative during the winding movement of the curtains shift the axis of the movably mounted gears to predetermined positions, while maintaining all the gears in mesh, for the purpose of adjusting the width of the exposure slot between the curtains prior to an exposure, and the said positions are set by a mechanism rendered operative by actuating a shutter speed-setting member. The shutter shown comprises two curtains 25, 26, Fig. 8, of which curtain 26 is wound on a drum 34 and is also connected to a spring roller 30, while curtain 25 is wound on pulleys 28 and is connected to a spring roller 31. Each pulley has one flange with peripheral teeth meshing with a pinion on a rotatable shaft so that the pulleys rotate together. One pulley 28 is mounted on a sleeve shaft 35, Fig. 20, geared at 36 to a gear 37, mounted on a movable stud 38 carried by a link 46. Gear 37 meshes with a gear 39 mounted on a movable stud 40, which is linked at 48 to stud 38 and at 47 to a fixed shaft 42 carrying a gear 41 that meshes with the gear 39 and a gear 43 on the shaft 44 of drum 34. Thus, movement of studs 38, 40 would effect differential rotation of the gears 36, 43 and consequent variation of the width of the exposure slot E between the curtains 25 and 26. Before setting the shutter, a knurled knob on the camera body is rotated so that cams 86, 110 and 120, Fig. 6, carried on the shaft 121 thereof position various shutter elements so that an exposure slot of required width is formed when the shutter is set and so that an exposure of the desired duration will result upon release of the shutter. Thus, rotation of this knob causes cam 86 to rotate and position the surface 87, 88 or 89 thereof against which is to bear, on release, the end 85 of the shutter release lever 71, which is pivoted at 73, Fig. 6, and spring-urged clockwise at 72. On release, the end 85 of lever 71 contacts the cam surface 87 for bulb exposures, cam surface 88 for slow exposures and cam surface 89 for fast exposures. The rotation of cam 110 results in rotation of a lever 99 about a pivot 100, Figs. 6 and 7 ; this lever is connected by a web 99a, Fig. 7, to a lever 98a which is thus moved to position a stud 101 thereon so that, for slow and bulb exposures, this stud will enter a slot 131, Fig. 20, in the link 46 and bear on a cam surface 102 thereof, when the shutter is set ; lever 98a is at one end in the form of a gear segment 98 meshing with the gear 97 of a retard mechanism 93-97, Figs. 6 and 7. The cam 120 contacts a stud 126 on a bell-crank lever 123, which is pivoted at 124, spring-urged clockwise at 125 and carries, on a pivot 83, a latching arm 58 that is spring-urged anticlockwise at 59, has a lug 57 riding on the cam surface 56 of lever 54 pivoted at 55 and has a stop 60 ; rotation of cam 120 by means of the knurled knob on the camera body thus causes the lever 123 to position the stop 60 on latch 58 relatively to a lug 61, Fig. 20, on the link 46 whereby the exposure slot formed during setting of the shutter is determined. The shutter is set by clockwise rotation of the shaft 42, Fig. 20, by means of an external knob carried by a shaft that can be clutched to shaft 42 upon depression of the knob against spring action. Such rotation of shaft 42 causes rotation of the gears 41-36 and movement of the curtains 25, 26 across the exposure aperture of the camera in overlapping relationship. During such movement, pulleys 28 rotate clockwise and, when they have almost completed one revolution, a pin 50 (Fig. 4, not shown), on one pulley strikes the upper side of a flange 52 on an arm 53 of the lever 54, the curtain 25 having at this time been fully wound up. Lever 54 is thus caused to rotate anticlockwise about its pivot 55 whereby (1) a spring latch 130 on a lever 132 pivoted at 133 to the arm 53 is moved out of the slot 131 in the link 46, and (2) latch 58 is allowed to pivot anticlockwise under the action of spring 59 and position the stop 60 in the path of the lug 61 on the link 46. Since curtain 25 is fully wound, further clockwise rotation of pulleys 28 is prevented and an arm 75 of release lever 71 engages a notch 79, Fig. 7, in the pulley adjacent gear 36 to prevent anticlockwise rotation of the pulleys under the action of spring roller 31. Further rotation of shaft 42 thus causes movement of curtain 26 only and, during such further rotation, the axes of the planet gears 37, 39 move and the lug 61 on link 46 snaps past the stop 60 of latch 58. When the knob on shaft 42 is released, the curtain 26 moves under the action of spring roller 30 until the lug 61 on link 46 is arrested by the stop on latch 58. At this time, the curtains 25, 26 define therebetween the required slot for the next exposure. Release of the shutter is effected by depression of a trigger on the camera body causing anticlockwise rotation of lever 71 against the action of spring 72 so that the arm 75 of lever 71 leaves the notch in the pulley 28 and the end 85 of lever 71 abuts the appropriate surface 87, 88 or 89 of the cam 86. For a bulb exposure, the rotation of lever 71 is such that an arm 76 thereof, Fig. 6, holds a pallet 91, pivoted on an arm 105 which is rockable by another arm 77 of lever 71, in engagement with a star wheel 92 of the retard mechanism so that the latter is locked and the exposure cannot be completed until the lever 71 is again released. During the exposure movement, the curtains 25, 26 move together across the exposure aperture until curtain 25 has fully run down. At this time, the pulleys will have almost completed one revolution in the anticlockwise direction and the pin 50 (Fig. 4, not shown) on one pulley strikes the under side of the lug 52 of arm 53 and causes the lever 54 to rotate clockwise whereby the stop 60 of latch 58 is moved out of the path of lug 61 on link 46 and curtain 26 continues to move under the action of its spring roller 30 to close the slot E after a time, determined by the retard mechanism and the position of the stud 101 on the arm 98a of gear segment 98 in the cam slot 131 of the link 46. Further operation of release lever 71 is prevented by a lug 154, Fig. 6, carried by the arm 53 of lever 54 and engaging over or in a notch of an extension of the arm 75 of the lever 71, this lug being moved to its operative position when the lug 52 on arm 53 is struck by the pin 50 (Fig. 4, not shown) on pulley 28.