Patent GB-461968-A (GB)
Title: Improvements in or relating to photographic cameras
IPC: G03B9/08
Filed: 1935-08-23
Abstract: 461,968. Photographic shutters. BAKER, W. E. W., and RUSHTON, R. H. Aug. 23, 1935, No. 23680. [Class 98 (i)] A camera is provided with a focal plane shutter comprising two longitudinallymoving blades 43, 44, Figs. 2 and 4, separately movable in the same direction to expose the film but movable in contact with one another in the reverse direction to set the shutter, latches 53, 60 associated with the respective blades to hold them in the set position against the action of springs 49, 67, and a release member 71 movable into engagement with the latches to release the blades in succession. Means are provided so that while the shutter is being set a release pin 83, Fig. 1, is projected from the camera, and an escapement mechanism is provided to regulate the time of exposure of the film. The shutter is set by moving a film-feeding rack 99 which carries a dog 100 to move the shutter blades so that pins 58, 81 engage the latches 60, 53. At the same time the dog 100 engages a block 72, Fig. 1, on a longitudinally-moving rod 73 carrying a block 75 formed with cam surfaces 76, 77. The surface 76 engages a pin 78, Figs. 7 and 8, on a bell-crank 79, the other end of which disengages an arm on the spring-pressed pin 81 to allow the release button 83 to rise. Further movement of the block causes the cam 77 to engage and depress a pin 93 on a lever 91 whereby a pin 97 rises out of contact with a cam 96 on an L-shaped lever 94. The axle of the lever 94 carries a coiled spring 101, Fig. 2, to bias the lever in a clockwise direction, Fig. 7, so that a V-shaped projection 98 engages the cam 77 and latches the block 75 and retains the rod 73. During the rotation of the lever 91, a cam 89 on the vertical arm 90 raises the spindle 81 whereby the button 83 is protruded ready to release the shutter. On depressing the button 83, for release of the shutter, a pin 85 engages the cam 89 and releases the lever 91 to its original position. Downward movement of the pin 97 results, which depresses the cam 96 and raises the projections 98 from the recess in the block 75 and allows the rod 73 to return under the action of the spring 74. Return of the rod 73 may be checked by an escapement. On the return movement of the rod 73 a cam 71 engages first a tappet 69, Fig. 4, to release the latch 52 and afterwards a tappet 70 to release the latch 60 thus releasing the shutter plates 43, 44 in succession. During this movement the pin 93 is raised and the arm 84 turned to lock the operating pin 83 in its depressed position. The escapement mechanism comprises a vertical spindle 104, Figs. 2 and 6, which carries a coiled spring biassing it in the direction of the arrow and carrying an arm 105 and toothed sector 106 meshing a pinion 107 on a gear wheel 108 driving a non- circular wheel 110. Mounted on a second spindle 111 is an oscillating lever 112, 113. The arm 112 carries a pin 114 adapted to be struck by the non-circular wheel when the gear train is driven. The lever 112, 113 is spring-pressed in a counter-clockwise direction, its movement being limited by a bob 115 abutting against an adjustable stop 106, Fig. 2. The spindle and arm 117 co-operate with a cam 118, Fig. 2, operable by a knob 120, Fig. 1, to hold the pin 119 out of contact with the wheel 110 to allow rapid operation of the shutter. The end of the rod 73 carries a block 121 bearing against the arm 105, movement of which is checked by the escapement when the pin 114 is in engagement with the wheel 110. To adjust the timing of the shutter, the distance between the tappets 69, 70 is variable. For this purpose the tappet 70 is carried on a rod 65 which bears against the arm 64 and is adjusted by means of a boss 123, Fig. 2, engaging a slot in an arm 125 mounted on a spindle 126 which also carries an arm 127 co-operating with a cam 128, Fig. 1, formed on the underside of the cam 118 so that rotation of the knob 120 shifts the boss 124 and thus alters the timing of the shutter. The film feed is as described in Specification 462,018.