GB1327940A - Shutter device - Google Patents

Abstract

1327940 Photographic shutters CANON K K 1 Dec 1970 [1 Dec 1969 12 Dec 1969 18 Dec 1969 27 Dec 1969] 57047/70 Heading G2A A shutter device has a blade ring 3 arranged to move so that the shutter blades 3' open at a constant rate, and a flash synchroniser switch which is closed by the blade ring when the blade opening reaches a value determined for an appropriate flash exposure. A shutter release lever 2 is depressed in the direction of arrow A so that a stepped portion 2b engages with and rotates a latch member 13 to free control lever 14. A main switch 12 is closed to energize an exposure control circuit and an electromagnet 28 and an anchor 18 of a delay device starts to move. A gear 17, with a pin 19, starts rotating in a clockwise direction under the action of a spring (not shown) and frees lever 16. The blade ring 3 thus rotates under action of a spring 30 and the shutter opens at a constant rate. For EE photography, opening of contacts 42 allows a condenser to charge at a rate determined by scene illumination incident upon a photo-conductor. At the end of the exposure interval, an electromagnet 28 is de-energized. Lock pawl 26 is freed for rotation (lever 20 having been previously rotated by bottom end portion 2c of shutter release 2) and a convex end 26a thereof engages and rotates lever 16 counter clockwise and thus closes the shutter. The maximum value of the opening of the shutter is indicated in a viewfinder 46 by a lever 44 which is frictionally pivoted and reset by member 47. For flash operation, a change-over ring 29 is positioned according to the film guide number, and at the same time switches a fixed resistance in place of the photo-conductor in the control circuit to give a fixed shutter time. A distance ring 39 is also adjusted to the object distance. An adder member 4 rotates about a pin 7 during these movement so that a contact member 40 thereon lies in the path of movement of a pin 41, the position of contact member 40 thus determining the aperture opening of the shutter and at the same time ensuring that the flash occurs when the shutter is at the maximum aperture. The shutter is designed to allow for the rather long time-to-peak characteristic of a flash bulb. Alternatively, a flash discharge tube is used, and arrangements are described, Fig. 9-12, (not shown), using a contactless synchronizer, either associated with the electronic timing circuit or using a lamp which illuminates a phototransistor in the discharge tube trigger circuit, the lamp being lit upon de-energization of the electromagnet 28.