Patent GB-698409-A (GB)
Title: Improvements relating to photographic cameras
Inventor: STUDDART MAURICE EYRE PERSSE
IPC: G03B9/34
Filed: 1949-07-13
Abstract: 698,409. Photographic cameras. WRAY (CAMERAS), Ltd. July 13, 1950 [July 13, 1949], No. 18535/49. Class 98 (i). In a photographic camera, the successive release of the two blinds of a roller-blind shutter is effected by a spring actuated release member which has a part engaging at an unvarying stage in the revolution of the release member, a member to release one shutter blind and another part for engaging a member, which can be moved to vary the stage in the revolution at which it is engaged, to release the second shutter blind. In the reflex camera shown in Fig. 3, the movable mirror 17 and the focusing screen 20, which has a small magnifying lens 25 cemented thereto, are carried by a frame 18 supported by a rotatable shaft 19 bearing similar projecting arms 28, 29, Figs. 1 and 8. Arm 28 carries a pin 30 which, when the mirror is in the receiving position, is engaged by a hook 31 on a pivoted member 32, spring urged at 39. When an exposure is to be made, a trigger 35 is depressed against the action of a spring 36, Fig. 2, so that a conical portion 37 thereof contacts a lip 38 on member 32 to rock the latter against the action of spring 39 and release hook 31. Thereupon mirror 17 and screen 20 swing to the inoperative position under the action of a. spring 41 coiled round a rod 40 which slides in a plate 42 and is connected to the arm 29 of rod 19. The shutter consists of a first blind 6 connected to a spring roller 7, Fig. 6, and by tapes to pulleys 9, 10, and a second blind 12 connected by tapes to a spring roller 16 and to a roller 13, Fig. 2, which lies between pulleys 9 and 10 and is freely rotatable on the shaft carrying them. Mounted on a fixed rod 44, Fig. 1, is a cam member 45 having integral therewith a gear 46 and forming at 47 a housing in which there is a spring 48, secured to member 45 and to a sleeve 49. This sleeve is freely rotatable on rod 44 and has its upper end formed as a disc 50 bearing a radial projection 51, a pin 58 on its underside and an inclined ramp 65 on its upper surface, Fig. 8. When spring 48 is fully wound, the projection 51 contacts an arm 52 of a member 53, pivoted at 53a and having another arm 56 with a slot 55 in which rides a pin 54 on the arm 29 carried by shaft 19. Thus, when the mirror is moved to the inoperative position on depression of trigger 35, movement of the arm 29 rocks member 53 and thereby moves the arm 52 thereof out of the path of projection 51. Spring 48 thereupon rotates disc 50 and during such rotation, pin 58 on this disc contacts one arm 59 of a spring urged lever 60, Fig. 8, pivoted at 61 and having another arm 62 with a downwardly extending part 63 contacting a stop 64 on pulley 9 so that lever 60 is rotated to release pulley 9 and hence the first blind 6. Thereafter, ramp 65 rotates a tapper 66, mounted on a horizontal axis in a slot 68 in a cam plate 69, so that a spring biased member 78 pivots about a rod 81 and an arm 83 on said member is released from a stop 84 on roller 13 whereby the second blind is released. The cam plate 69 is freely rotatable about rod 44 and has a central boss which projects through the top 70 of the camera body 1 and a squared hole in a finger wheel 73, Figs. 1 and 8. Rod 44 also passes through this hole and terminates in a plate 74 between which and the finger wheel is a compression spring 75, Fig. 1. Several holes are provided in the lower surface of wheel 73 and a pin 76 on the surface 70 of the camerabody can be made to engage any one of themby lifting and then turning the finger wheel. Hence, the position of the tappet 66 and thereby the exposure time can be altered, the exposure time selected being indicated by graduations on plate 74. After the tappet 66 has been actuated and an exposure completed, disc 50 continues to rotate until the projection 51 thereon engages an upturned nose 88 on member 53 which was positioned in the path of this projection when member 53 was rocked on release of the mirror 17. The mechanism necessary to effect an exposure is set by a single half-turn of a knob 89, Fig. 3. This knob is carried by a shaft 90 having integral therewith a spur wheel 91 and a hollow cylindrical drum 92 having diametrically opposed slots 93 therein and terminating in a disc 94 formed with two diametrically opposite radial teeth 95, engageable by a hook 96 on a bell crank 97 which is pivoted at 99, Fig. 6. The other arm 98 of this bell crank is spring urged at 100 into contact with the lower end of blind roller 13 which has a dimple-like projection 101 causing rotation of the bell crank and release of the hook 96 from a tooth 95 when an exposure has been completed. The spur wheel 91 drives a spur wheel 102 having half the number of teeth and wheel 102 drives a similar wheel 103 meshing with the wheel 46 so that spring 48 is wound up. Wheel 46 meshes with a spur wheel 104 on the shaft 128 of a film sprocket 105 so that film 3 is fed through one frame. Spur wheel 103 is slidable on a pin 205, Fig. 2, and a wedge-shaped projection 108 on its underside normally engages a socket 109 on the bottom of the camera body. A dog 110 provided on the upper surface of wheel 103 is adapted to engage a slot 111 on the underside of pulley 10. Such engagement occurs when knob 89 rotates wheel 103 anti-clockwise so that the projection 108 is cammed out of socket 109 and the wheel is raised. Thus the rotation of the wheel causes rotation of the pulley 10 so that the shutter blinds are wound up. Towards the end of a revolution of wheel 103, stops 64 and 84 move behind the spring urged levers 63, 83, Fig. 8, which prevent premature release of the shutter and, when wheel 103 has completed a revolution, wheel 103 descends under the action of a spring 106, Fig. 2, and the projection 108 re-engages socket 109. When the hook 96 engages a tooth 95, a spring loaded detent 112, Fig. 6, engages one slot 93 and a roller 192 carried by an arm 190 pivoted at 99 and spring biased at 191 engages the other slot 93. Rotation of disc 50 during movement of member 45 by knob 89 is prevented by engagement of nose 88 with projection 51. The housing 47 of cam member 45 has a helical ledge 113 thereon, Fig. 1, which bears on a roller 114 carried on the pin by which rod 41 is pivoted to arm 29 so that, in completing a revolution, cam member 45 moves mirror 17 and screen 20 into viewing position and fin 30 is engaged by hook 31. As arm 29 moves downwardly, the pin 54 thereon rocks member 53 so that nose 88 is moved away from projection 51 and the latter is moved into contact with the arm 52. The sprocket shaft 128 has a gear thereon meshing with a gear 117, Fig. 1, on a sleeve 120 which drives through friction by a spring 125 a take-up spool 116 in a cassette 5. Sleeve 120 extends through camera body 1 and carries a disc 121 formed with a rim 122 having a notched projection 123 and the gear ratio between shaft 128 and sleeve 120 is such that for each revolution of the shaft, the sleeve 120 turns through slightly less than a revolution and the projection 123 registers with a different one of a series of numbers on the camera body indicating the number of exposures made. Sprocket 105 is freely rotatable on the shaft 128 and is normally driven by engagement of a sleeve pin on the shaft with a notch on the sprocket. In order to wind the film independently of the shutter movement, this drive may be disengaged by pulling upwards a collar 124 on the take up spool 116 so that a pivoted member having a forked end acts between flanges on a sleeve carried by shaft 128 to move the sleeve downwardly against the action of a spring. The film may then be wound onto spool 116 by a handle attached thereto or may be rewound into a cassette 4 by another handle. Retardation of the disc 50 for longer exposures is effected by a mechanism comprising a flywheel 137, Fig. 4, geared to a shaft 144 which forms at its lower end a bearing for the sprocket shaft 128 and carries a pinion 145 meshing with a toothed segment 146 provided on an arm 147 pivoted at 148 and carrying a roller 149, Figs. 4 and 8, which is held in engagement with the periphery of the cam plate 69 by a bowed spring 150. This plate 69 is shaped so that for the longer exposures, the tip 153 of the segment 146, Fig. 4, lies in the path of the projection 51 of the disc 50 after the first blind 6 has been released. For a bulb exposure, cam plate 69 is turned by finger wheel 73 until a notch in the plate periphery comes beneath the turned down end 154 of a member 155 pivoted on the pin 81, Fig. 8. This member has a downwardly extending arm 156, Fig. 2, riding against a conical portion 157 on the trigger rod 35 so that the member 155 cannot turn under the action of spring 158 until the rod 35 is depressed. Member 155 has a second arm 159, Figs. 2 and 8, which, when the notch is beneath the end 154, lies in the path of the stop 84. Thus, when stop 84 is released by lever 83, it is immediately reengaged by the arm 159 and rotation of disc 50 is arrested until the trigger rod 35 is released whereupon the conical portion 157 on the rod displaces the arm 156 so that arm 159 releases the stop 84. Specification 656,548 and 691,103 are referred to.