Patent GB-1184758-A (GB)
Title: A Photographic Shutter with a Reciprocating Shutter Actuating Part and an Electronic Timing Device
IPC: G03B9/58
Filed: 1968-06-25
Abstract: 1,184,758. Camera shutters. PRONTORWERK ALFRED GAUTHIER G.m.b.H. June 25, 1968 [July 21, 1967], No.30125/68. Heading G2A. In a camera having a shutter which is opened and closed by means of reciprocal movement of a driving member, and which has a device for delaying the opening movement to compensate for time lag of the shutter mechanism, the driving member is latched open during the exposure period. An electronic timing device de-energizes an electromagnet at the end of this period, which then releases a spring-loaded lever which unlatches the driving member. Fig.1 shows the mechanism in the cocked position. The spring-loaded driving disc 5, held in the cocked position shown by a stop lever 10, is connected by a drive pawl 7 to a lug 8a of the shutter blade driving ring 8, so that rotation of disc 5 in the direction of the arrow causes pawl 7 to execute a reciprocating movement, which opens and then closes the shutter blades. The driving ring 8 has another lug 80 and when the ring has rotated clockwise into the "shutter open" position Fig.2, (not shown), a spring-loaded catch 14 engages behind lug 8b, and locks it against return. During the "opening" movement, lug 8a also engages a spring-loaded brake lever 29 cooperating with a heavy rotatable disc 30, which forms the compensating mechanism referred to below. A spring-loaded actuating lever 17 and a spring-loaded lever 19 are both pivoted on a pin 13. Lever 19 is locked, against its spring, in the cocked position of Fig.1, by a pawl 18. Lever 19 has pivoted to it at one end an armature 20 which, in the cocked position shown, abuts against the electromagnet 21. The mechanism is set in the cocked position by two levers 35, 36, both pivoted on a pin 34, and inter-engaging so that they move together. As driving disc 5 is rotated in the cocking movement, a pin 5a thereon engages against the end of lever 36, thus pivoting levers 35 and 36 clockwise, and hence levers 17 and 19 anticlockwise. When shutter release 12 is pressed, movement is transmitted via a lever 11 to stop lever 10, which disengages from driving disc 5, so allowing it to run down clockwise. At the same time an electronic timing device 23 is switched into circuit, and the electromagnet 21 is energized, so holding the armature 20. The shutter blades are now locked in the "open" position Fig. 2, (not shown) by the latch 14 falling into place behind the lug 8b of the shutter driving ring. After the set time has elapsed, the electromagnet 21 is de-energized, and the armature 20 released. Lever 19 is now free to pivot clockwise, a pin 27 thereon engaging pawl 18 and disengaging it from lever 17. This in turn is thus free to move under the action of spring 16. An arm 17b of lever 17 then strikes against a pin 14a on catch 14, knocking it free of lug 8b, so that ring 8 is free to rotate anticlockwise once more and so close the shutter blades. As the catch 14 is not released directly by the magnet armature but by the lever 17 as an intermediate element, variations in time lag of the movement of the actual mechanical parts is reduced, and spring 16 is made as strong as possible so as to reduce the movement time of catch 14 in disengaging from lug 8b to as near zero as possible. Variations due to different shutter time settings are compensated for by the mechanism 28-30.