Patent GB-782237-A (GB)
Title: Flashlight synchronisation device for photographic cameras wirh roller blind shutter
IPC: G03B9/70
Filed: 1955-11-18
Abstract: 782,237. Photographic flashlight synchronization apparatus. AGFA CAMERA-WERK AKT.-GES. Nov. 18, 1955 [Nov. 22, 1954], No. 33137/55. Class 98(1) A flashlight synchronization device of the kind having an ignition contact controlled by a running- down shutter part and particularly for use with a rollerblind shutter comprises a setting contact member adapted to move in conjunction with the shutter setting means to explore a series of contact elements and to remain in contact, according to the shutter setting, with one of them, each of such contacts being separately electrically connected to a corresponding alternative contact, and the alternative contacts being positioned for exploration by an ignition contact member moving in conjunction with a running-down shutter part, the ignition circuit being closed when the ignition contact member contacts that alternative contact which is connected to that contact element at that movement contacting the setting contact member. As shown, the shutter speed setting knob 2 controls through a spindle 3 and cam 4, the speed setting of a roller-blind shutter having a roller 5 for the first blind and a roller 6 for the second blind, a cam 7 for the release of the second blind being fixed on the spindle 8 of the roller 5. The cam 7 controls mechanism for regulating the movement of a disc 26 rotatable on the spindle 8 and connected to the roller 6 by a pin 27 projecting through a circular slot 28 in the roller 5. Coaxial with the spindle 8 is an insulating contact carrier 9 carrying contact elements 10 and alternative contacts 11, each element 10 being connected with a contact 11 by a cable 12. The carrier 9 is coupled to the fixed member 15 by screws 13 passing through slots 14 in the carrier 9, the carrier having a milled projection 16 enabling it to be turned through an angle determined by the length of the slots 14. A current - conducting ring 18 fixed to the insulating bush 17 fixed to the spindle 3 carries a contact spring 19 sliding over the elements 10 when the knob 2 is turned, the ring 18 being connected by the contact spring 20 to a contact 21 paired with a contact 23, following the movement of the shutter release, connected to the flash-bulb socket 22. A bush 24 fixed to the spindle 8 carries a spring-urged contact pin 25 sliding over the contacts 11 and connected to the earth side of the ignition circuit. When the shutter speed is selected by turning the knob 2 the contact spring 19 is placed on the appropriate contact element 10 (Fig. 2)., and the pin 25 takes up the position shown. Operation of the shutter release closes the contacts 23, 21, and as the first blind roller 5 turns the pin 25 turns clockwise to wipe over the contacts 11 until it reaches that connected via contact element 10 and spring 19 to the contact 23, when the flash-bulb is ignited. By suitable location of the contacts 11 on the carrier 9, the maximum amount of light is always emitted when the exposure slit between the blinds is symmetrical with respect to the centre line of the image opening. Adjustment to suit flash-bulbs of different characteristics is performed by turning the carrier 9. The contact elements 10 may be further elongated to ensure good contact even when the knob 2 is not accurately set. The device may be adjusted for any distances between. the markings on the speed dial by suitable arrangement of the contacts 10, 11. In the reverse movement of the pin 25 during setting, firing of flashbulb cannot take place because the contacts 23, 21 are open. In a modification, the pin 25 reaches its initial position at the end of the running-down movement of the shutter, and since in this case the coupling between the pin 25 and the spindle 8 is operative only in one direction of movement, the contact spring 20 is directly connected to the socket 22, the contacts 23, 21 being omitted. The contacts 11 and the contact elements 10 may be arranged in straight lines and the pin 25 and the spring 19 caused to slide longitudinally.