Patent GB-284351-A (GB)
Title: Improvements relating to shutter devices for photographic apparatus
IPC: G03B9/22
Filed: 1928-01-28
Abstract: 284,351. Wolf, J. Jan. 20, 1927, [Convention date]. Shutters with pivoting blades. -In diaphragm shutter mechanism means are provided whereby the spring barrel 5, Fig. 4, operating the shutter blades can be arrested as shown with the blades open by a lever 12 which automatically moves to its effective position during the winding of the barrel 5 from the position in Fig. 1 to that in Fig. 2, and is held there by a detent 13<d> which is moved to effective position when the barrel is fully wound and may be held there for a period determined by the exposure time control mechanism A. The latter is wound up automatically to an adjustable extent on winding the barrel 5. The shutter may also be provided with a delay mechanism B controlling a lever 8 which will delay the commencement of the running down movement of the barrel 5 for an adjustable period after the barrel is released from the lever 4 by operating the trigger 1. On winding the barrel 5 anticlockwise the crank arm 6a reciprocates without engaging the pin 6<c> controlling the blades, and the spring lever 12 moves into position when released by the flange 5a so that the shaped projection 12<c> can engage the flange 5<a> and hold the barrel 5 on the return movement. The barrel 5 is held set by the lever 4 pivoted at 4<a> which springs behind the flange 5<a> under the action of the spring 4b on the pin 4<c>. This movement of the pin 4<c> rocks the curved short end of the lever 15 which is pivoted at 15<a>, the other end engaging a pin 13<c> on the pawl 13 to bring the pawl out of engagement with a notch 14<a> of the disc 18, and thereby also rocking the tail detent 13<d> into position to hold the lever 12, Fig. 4. During the winding of the barrel 5 the flange 5<a> also rocks a lever 16 which tensions a spring 17<a> and thereby rocks an arm 17 having a sector which winds the disc 18 of the control mechanism. The extent of this winding is determined by an adjustable stop pin 24 on a sector 24<b>, Fig. 1, which pin limits the movement of a toothed ring 22 in gear with the disc 23 coaxial with the disc 18. Also at the end of the winding movement of the barrel 5, Fig. 2, the clockwise movement of the lever 15 rocks a spring arm 21 on which the escapement 20 is mounted, retracting the latter from engagement with the mechanism A. This escapement controls the longer exposures, a second adjustable escapement 35 being provided for shorter exposures. The effective engaging action of escapement 20 can be controlled by a pin 21<c>, or the escapement held inoperative by an outside setting pin 21<d>. On actuating the trigger 1, thereby releasing the lever 4 indirectly through a pivoted lever 3, the return anticlockwise movement of the lever 15 releases the escapement-arm 21, and the lever 16 is freed. The spring disc 18 rotates under control of the escapement mechanism until the notch 14<a> allows the spring pawl 13 to rock and free the lever 12, so that the barrel 5 pushes past the projection 12<c> and completes the exposure. For bulb or time exposures a spring-controlled shaped disc 25 has a projection 25b adapted to prevent the lever 15 returning immediately the trigger 1 is operated. The disc 25 also has a resilient leaf spring 25<c>, Fig. 6, on which is a wedge-shaped pin 25e passing through the disc; and also a pin 25<g> with which one or both of two spring levers 26, 27 engage. These levers are normally held retracted by a stronger spring arm 28 acting on the levers 26, 27 through a pin 27<a> on the lever 27, the lever itself holding a pin 26<c> on the lever 26. The lever 28 can be set to bring either or both of the levers 26, 27 into operation by a pin 24a on the exposure setting ring 24, and in such position the pin 24 will prevent the spring disc 18 being wound. When the lever 26 only is set, for bulb exposures, it abuts against a pin 3<d> on the lever 3. On actuating the trigger 1 a projection 3<i> on the lever 3 first engages the resilient pin 25e and rotates the disc 25 against its spring 25<h>. Instead of tha disc returning completely after the projection 3<i> passes the pin 25<e>, the disc is arrested by the projection 25<g> engaging the lever 26 before the end 3<c> of the lever 3 operates the release lever 4. In this position the nose 25b prevents the lever 15 returning and the pawl 13 is held in operative position until the trigger 1 is let go. The projection 3d on the lever 3, which is spring- returned, then forces the lever 26 out of engagement with the stop 25<g> and the disc 25 returns and releases the lever 15, the pawl 13, and the holding lever 12. When the lever 28 is set to release both levers 27, 28, the first return action of the lever 3 releases the lever 26 from the projection 25<g>, but the latter engages a notch in the lever 27. On the second actuation of the trigger 1 the projection 3d on the lever 3 engages an inclined face 27<c> of the lever 27 and thereby releases the disc 25. Specifications 275,462 and 284,329, the latter describing the delay mechanism B, are referred to.