Patent GB-497302-A (GB)
Title: Improvements in or relating to foldable or collapsible photographic cameras and shutters therefor
IPC: G03B19/04
Filed: 1937-10-21
Abstract: 497,302. Shutter mechanism for collapsable cameras. KODAK, Ltd. Oct. 21, 1937, No. 28719. Convention date, Oct. 30, 1936. [Class 98 (i)] In a foldable or collapsable photographic camera, parts of the shutter mechanism are mounted at the camera front and other parts thereof are mounted in a casing movable relatively to the camera front, the arrangement being such that when the camera front is in picture-taking position, the two groups of parts are in operative relation. The invention is described as applied to a camera, Fig. 1, constructed for folding in the manner set forth in Specification 464,781. The shutter operating and control mechanism are now contained in a casing 39 pivoted to the camera case and adapted, with the camera in folded condition, to overlie the lens portion 36 and shutter housing 34. These mechanisms include a master driving member ; setting means therefor, including a crank 64, Fig. 4, that may also wind the film; trigger mechanism, and means to prevent actuation of the trigger until the setting means has returned to home position ; escapement means for controlling the shutter speed and adjusting means therefor, comprising a wheel 94 adapted to traverse a scale beneath a window 101; and means under the control of a handle 150 to utilize the escapement means for delaying exposure until after a predetermined interval. The camera case is provided with a rangefinder 37 and exposure-determining means 38, not described in detail. The shutter. The shutter 45, Fig. 4, is of the multi-blade type and is situated in a housing 34 connected to the pivoted casing 39, Fig. 1, by studs 43 slidable in channels 42. An arm 49 extends upwardly from the shutter ring 48 and is normally held by a spring detent secured to the housing. As the housing reaches its foremost position, during the opening of the camera, the detent is disabled by abutment with a lug on the pivoted casing and the arm enters a notch in an actuating link 50. This link is spring-urged counterclockwise about its pivot on a toothed disc 52 meshing with teeth 56 on a master driving member 57, the notch in the link being so shaped that the clockwise setting movement of the driver is ineffective to actuate the shutter, whereas the subsequent counterclockwise movement of the driver causes the shutter to open and close. The driver is ring-shaped and rotatable about an upstanding cylindrical support 58 adapted to receive the lens when the camera is collapsed. Setting and trigger mechanisms. The means for setting the master driving member 57, Figs. 4, 8, and 13, comprises a slide 67 connected by a cord 66 to the film winding-crank 64 and adapted, upon operative movement of the crank, to abut a stud 61 on the driver and rotate the latter clockwise against the action of a spring 62. The driver is retained in set position by the engagement of its shoulder 69, with a trigger 70 that is spring-urged clockwise about the left-hand end of a lever 72, pivoted on a stud 73 and spring-urged counterclockwise. The trigger is actuated by a finger piece (not shown) that extends through the casing 39 and is carried by a fork 75 at the left-hand end of lever 72. Actuation of the trigger is prevented until the setting slide 67 has been spring-restored to home position. For this purpose, the fork 75, Fig. 13, is connected by a rod 105 to a lever 104, clockwise rotation of which about its pivot 104<1> is normally prevented by a lug 106 extending downwardly from the lever into a circular recess 103a in the disc 52. However, upon the return of the setting slide, a projection 107 cams the lever 104 upwardly to remove the lug from the recess and thus release the lever and trigger. Shutter-speed control. The speed of the shutter is adjustable from " Bulb " to 1 /200 of a second by a wheel 94, Fig. 1, extending through the casing 39. Rotation of the wheel, by a pinion 93, Fig. 19, sets a ring 86, Fig. 24, angularly with respect to the cylindrical support 58, whereby peripheral cams on the ring are positioned relatively to the members of the control mechanism. In addition, a cam 96 projecting inwardly of the disc positions a scale 100 beneath a window 101 in the casing to indicate the shutter speed selected. To maintain the shutter in open condition for the selected period, means are provided to arrest the driver 57 midway of its operative travel. For this purpose, the driver has pivoted to it a latch 130, Figs. 8 and 13, adapted to co-operate with abutments 85b, 85c, Fig. 25, on a detent ring 85 rigidly connected to a gear ring 78, Fig. 23, urged counterclockwise about the cylindrical support 58 by a spring 80. The arrangement is such that, during the clockwise setting movement of the driver, the latch 130 encounters the abutment 85b and carries the rings 85, 78 with it, thus stressing the spring 80. Now, upon the actuation of the trigger, the driver is released and is rotated by its spring until arrested by the engagement of the latch with the abutment 85c, in which position of the driver the shutter is open. Both the springs 56, 80 now tend to rotate the rings 85, 78 counterclockwise. This movement is retarded by an escapement mechanism 110, gearing with one of a pair of toothed segments 83, 84 on the gear ring 78. After an interval predetermined by the setting of the cam ring 86, Figs. 19 and 24, the latch rides up one of the cams 88, 89 on the cam ring and thus escapes from the abutment 85c, allowing the driver to proceed freely to shutter-closing position. The escapement mechanism comprises a gear train terminating in a star wheel that co-operates with an anchor escapement 123, Figs. 13, and 19, in usual manner. This mechanism is mounted. in a frame 114 spring-urged clockwise about a pivot 115 to cause a pin 121 on the frame to bear against the periphery of the cam ring 86. For slow shutter speeds, the escapement frame is rocked counterclockwise by a cam 92 on the ring 86 to engage the first wheel 116 of the gear train with segment 83 of the gear ring, the escapement mechanism being thus enabled to exert its maximum retarding effect and the time of exposure being proportional to the distance between the set positions of cam 89 and abutment 85c. For rapid shutter speeds, the escapement frame is permitted to rock clockwise by the part 90<1> of the cam ring, whereby the second wheel 117 of the gear train is meshed with segment 84 of the gear ring and the escapement mechanism thus exerts a lesser retarding effect, the time of exposure being now related to the distance between the set positions of cam 88 and abutment 85c. For the fastest shutter speed, a cam 90 rocks the escapement frame to an intermediate position in which neither of the wheels 116, 117 is engaged with the gear ring which, with the detent ring and driver, is now unretarded. For " Bulb " exposures, the escapement mechanism is engaged and the escapement locked by a lever 140, Fig. 19, under the control of the trigger. The adjustment of the cam ring 86 to "Bulb" position engages the escapement mechanism as for slow shutter speeds and positions a notch 137 beneath the nose of a spring-urged arm 134. Now, upon the actuation of the trigger, a lug 72a on the lever 72 frees the locking lever 140 to the action of arm 134, which rocks it clockwise into engagement with the escapement 123. Upon the release of the trigger, the lug 72a restores the locking lever and permits the shutter to close in the manner already described. To enable the driver to be set without operating the escapement mechanism, the pivot 115 of the escapement supporting-frame 114 is mounted on a bell-crank 111, Fig. 13, pivoted at 112 and capable of limited rocking movement to enable the gear segments 83, 84 to chaster past the selected escapement wheel 116, 117. Delaying exposure. The escapement means described above is utilized to delay exposure until after a predetermined interval. The rotation of the driver 57, Figs. 8 and 13, to set position, aligns a recessed part 57a of its periphery with a mutilated disc 146 that is thus freed for rotation by a lever 148, Fig. 4, terminating in a handle 150, Fig. 1. The disc is held in rotated position by a latch 155 urged outwardly of the disc by a spring to engage an abutment 57b on the driver, and in this position locks the driver by engagement of its convex periphery within the recess 57a. During this locking movement of !the disc, a toothed arm 151, pivoted thereto, chatters past a pinion 153 of the escapement mechanism. Now, upon the actuation of !the trigger, the driver moves sufficiently to disengage the abutment 57b from the latch and the disc is restored to home position by a spring, the movement being retarded by the escapement mechanism. On reaching home position, the disc releases the driver and the shutter is actuated in usual manner. This delay action device forms the subject-matter of Specification 24764/38.