Patent GB-284404-A (GB)
Title: Improvements in or relating to roller blind shutter mechanism for cameras
IPC: G03B9/34
Filed: 1926-10-28
Abstract: 284,404. Reh, H. Oct. 28, 1926. Shutters, roller-blind. -Relates to shutters of the kind comprising two blinds which, on actuation of the releasing device, are adapted to be coupled to each other to move across the focal aperture only after one of them has moved through an adjustable distance to form the exposure slot, and consists in setting the shutter by means of a disc which, when turned in one direction from its initial position to set the shutter for rapid exposure, actuates means which varies the interval which elapses before the blinds are coupled together, and also actuates means which alters the tension of the springs of the rollers which drive the the blinds; and which, when turned in the other direction, throws into action a timing mechanism for slow timed exposures. When the disc rests in its initial position, the shutter is set for time exposures. In the form shown, the blinds are actuated during exposure by spring-tensioned rollers 6, adapted to draw the blinds from upper rollers carrying gears 55, 56 meshing with gears 53, 54 loose on a spindle 50 rotatable, against the action of a spring 52, by a lever 51 for winding up the blinds. A toothed sector 57 on the spindle 50 engages a gear 58 loose on a spindle 17 and fast with a gear 59 having a pin 59<1> engaging an arcuate groove 60 in a gear 15 loose on the spindle 17, upon which spindle a gear 12 also rides loosely, the gears 12, 15 meshing respectively with the gears 53, 54. On rotating the lever 51, the pin 59<1> engages one end of the groove 60 and drives the wheel 15 to wind the lower blind, and a projection 16<1> on a catch 16 pivoted at 15<1> on the wheel 15 engages a pin 19 on the wheel 12 so that the wheel 15 takes with it the wheel 12 which winds the upper blind. At the end of the winding movement, the pin 19 and projection 16<1> snap into a notch 18' in the shutter releasing lever 18 pivoted at 18<2> to the casing, and on releasing the winding lever 51 the spring 52 returns the parts 50, 51, 57, 58, 59 to their initial positions, determined by the engagement of the pin 59<1> with the other end of the groove 60 in the wheel 15. The shutter is set for different exposures by a disc 1, mounted on a spindle 2, which is set for time exposures so that a mark on the disc registers with a fixed mark on the casing, and is turned clockwise from this setting to set the shutter for rapid timed exposures, and counterclockwise to set it for slow timed exposures. Rapid timed exposures. The spindle 2 carries two mutilated gears 3, 4 which are adapted, when the disc 1 is turned to set the shutter for rapid exposures, respectively to rotate two gears 5 and 24. Rotation of the gear 24, through gearing 24<1>, 25, 26 rotates the blind rollers 6 to vary the tension of the driving springs. Rotation of the gear 5 turns a gear 7 which is loose on the spindle 17 and is connected by pins 8, 8<1> with a wheel 9 which is loose on the spindle 17 and is provided with a peripheral cam portion 10. Loose on the wheel 9 is a ring 11 which has notches 11<1> round a portion of its periphery, and is coupled to the wheel 12 by a pin 11<11> engaging a short slot 12<1> in the wheel 12. The pin is constrained normally to engage one end of this slot by a spring 13 on the wheel 12 engaging a notch 14 in the ring 11. The wheel 12 being held, after winding the blinds, by the engagement of the pin 19 in the notch 18<1> of the releasing lever, the ring 11 is therefore also held, except for a limited movement, by the coupling 11<11>, 12'. When, therefore, the disc 1 is turned to set the shutter for a rapid exposure, the wheel 9 turns over the ring 11 so that its cam portion 10 uncovers a certain number of the notches 11<1> in the ring 11, the number depending on the setting of the disc 1. If, now, the releasing lever 18 is actuated, its notch 18<1> releases the projection 16' of the catch 16 pivoted on the wheel 15, and also releases the pin 19 on the wheel 12. The wheel 15 is then free to turn, but the wheel 12 and the ring 11 are held by a locking-lever 20 pivoted at 18<2>, which is caused by a spring rendered operative by the movement of the lever 18, to engage a pin 22 on the wheel 12 and also a notch 21 in the ring 11. The wheel 15 therefore turns alone, under the action of the driving roller of the lower blind, so that this commences to move over the focal aperture to open the slot between the blinds. During the movement of the wheel 15 a projection on the catch 16 is caused to ride on the cam surface 10 of the wheel 9 by a spring on the pivot 15<1> and when the projection reaches the end of this surface, it drops into the first uncovered notch 11' thereby locking the wheel 15 to the ring 11, and terminating the opening of the slot between the blinds. The ring 11 is permitted by its pin and slot connection 11<11>, 12<1> with the locked wheel 12 to turn sufficiently far to cause the notch 21 in the ring to displace the locking-lever 20 out of engagement with the pin 22 on the wheel 12, so that this wheel is now set free, and the two blinds, coupled together by reason of the locking of the wheel 15 to the ring 11, now move together over the exposure aperture. At the end of its movement, the lower blind is arrested owing to the engagement of the catch 16 with a resilient stop 23, which also, by rotating the catch 16 unlocks the ring 11, and therefore also the wheel 12, from the wheel 15, so that the upper blind continues to move until the pin 19 reaches the catch 16, thereby closing the slot between the blinds. Slow timed exposures. On winding up the blinds by means of the lever 51, the wheels 15 and 12 are rotated and locked as before to the releasing lever 18. The gear 59 in the winding train is coupled, through gears 35, 36 to a gear 32 which is loose on the spindle 2 and carries a pin 33 adatped to engage a pin 31<1> on a disc 31 also loose on the spindle 2, so that the wheel 32 is rotated, and carries with it the disc 31 against the action of a spring 38 until a locking tooth on a spring-controlled lever 40 drops into a notch 31<c> in the disc 31. On releasing the winding lever 51, the spring 52 returns the parts 50, 51, 57, 58, 59, 36, 35, 32 to their initial positions. When the disc 1 is turned to set the shutter for slow-timed exposures, the mutilated gears 3, 4 do not engage the gears 5, 24 so that the notches 11<1> of the ring 11 remain uncovered, and no additional tension is imparted to the blind springs 6. The rotation of the disc 1 causes an arcuate cam 27 on the gear 4 to displace a lever 29, pivoted at 28, so that a lever 30 fast with the lever 29 is moved out of the path of the pin 31' on the disc 31. The rotation of the disc 31 also rotates a mutilated gear 41 mounted on the spindle 2 so that a portion of the toothed part of its periphery, greater or less corresponding to the setting of the disc 1, is adapted, when the shutter is released, to engage a gear 42 which is pivoted on the disc 31 and is fast with an escapement wheel 43 controlled bv an escapement lever 45 also mounted on the disc 31. On actuating the releasing lever 18 to make the exposure, the wheel 15 is released as before, and the lower blind moves over the exposure aperture. The notches 11<1> being entirely covered, the catch 16 cannot engage the ring 11 to couple the blinds together, and therefore the wheel 12 remains locked by the lever 20 until the lower blind has traversed entirely the exposure aperture. On completion of this movement, a pin 15<2> on the wheel 15 turns the locking lever 40 out of engagement with the notch 31<c> of the disc 31, so that this commences to move under the action of its spring 38, its movement being braked by the escapement 43, 45 until the gear 42 rides off the effective part of the toothed portion of the gear 41, whereafter the disc 31 moves rapidly until a cam 31<a> thereon engages and rotates the arm 44<1> of a two-armed lever mounted on the spindle 18<2>, and thereby causes the other arm 44<2> to rotate the locking- lever 20 out of engagement with the pin 22 on the wheel 12. This wheel is now set free, and the upper blind therefore runs down and is finally arrested by the engagement of the pin 19 with the catch 16 resting on the buffer 23. A device is provided for preventing the lever 18, if this should be released prematurely, from re-engaging the pin 19 and prematurely releasing the locking- lever 20. Time exposures. The blinds are wound up and held as before. The disc 1 is set in the central position in which the gears 3, 4, as in the case of slow timed exposures, do not engage with the gears 5, 24, and therefore the notches 11<1> are entirely covered by the cam 10 and no additional tension is imparted to the blind springs 6. On actuating the releasing lever 18, the wheel 15 moves until the lower blind has run down, entirely opening the exposure aperture, but the wheel 12 controlling the upper blind is held by the locking lever 20, which is caused to engage the pin 22 when the lever 18 is actuated. On releasing the lever 18, the lever 20 moves back out of engagement with the pin 22 and the notch 18' re-engages the pin 19, a slight rotation of the wheel 12 taking place, owing to the absence of the projection 16<1> from the notch 18<1>, sufficient to move the pin 22 out of line with the locking notch on the lever 20. On again actuating the lever 18, the pin 19 is released, and as the locking-lever 20 cannot now re-engage the pin 22, the wheel 12 is set free, and the upper blind runs down to close the exposure aperture.