Patent GB-480891-A (GB)
Title: Improvements in or relating to photographic cameras
IPC: G03B7/04
Filed: 1936-10-21
Abstract: 480,891. Photo-electric control of photographic shutters. ZEISS IKON AKT.-GES. Oct. 21, 1936, No. 28656. Convention date, Nov. 6, 1935. [Class 98 (i)] In a focal-plane shutter con. trolled by the resistance of a photo-electric exposure meter, the slit-adjusting and resistance control knob is connected by means of toothed gear and a displaceable coupling member, with the drive for winding and releasing the shutter so as to influence the adjustment of the drive whilst the adjustment of the knob remains uninfluenced by the movement of the drive. In Fig. 1, the slit-adjustment knob 24 moving over a resistance 25 is rigidly connected to an arm 26 carrying the common shaft of planet wheels 17, 18. The wheel 18 acts on a wheel 19 carrying the disc 15, whilst the wheel 17 is connected through a wheel 16 to gear and bevel wheels 7, 8. A wheel 22 loosely mounted on the slit-adjusting shaft co-operates with the disc 15 through a pin 21 and projection 20, the pin being deflectable when under pressure. The disc 22 acts on the release lever 23 for the upper curtain of the shutter and is movable between two stops determining a small angle. The shutter winding knob 1 acts through gears 2, 3, coupling pins 4, 5, and gears 6, 7, 8, 9 on the band roller 10 of the lower curtain. The shutter releases knob, 13, is coaxial with the knob 1 and when pressed against a spring, acts on a lever 14 to move the gear 3 and release the coupling pins 4, 5 thus allowing the shutter to run down. The slit adjustment is set by the knob 24 which rotates the wheel 19 through the planet gearing to vary the distance between the projection 20 and the pin 21. When the shutter runs down, the planet gear 16, 17, 18, 19 and disc 15 are rotated and by means of the projection 20 and pin 21 carry the lever 23 along to free the upper curtain. Thereupon, the pin 21 is pressed laterally and allows the disc 15 to complete its motion. In a modification, the slit-adjusting and resistance-controlling knob acts through planet gearing to vary the relative angular position of the coupling pins which in turn determine the amount of difference in the winding up of the shutter blinds and hence the slit width. In a further modification, the upper blind release is effected by a lever which has a projection engaging a gear connected to the blind, the catch being released by a cam member or lug on a rotating gear acting on the lever. The position of the cam member is determined by the slit adjustment. In Fig. 3, the slit-adjustment and winding knobs are combined as a unit. The slit-adjusting knob is screwed to a sleeve 42 which is held from rotation by guide pins engaging axial slots in the hub of the winding knob 41. On this hub is rotatably mounted a gear 49 which rotates the curtain shaft through gears 50, 51, 52 and is itself driven by a disc 46. This disc is mounted on a tube 45 which moves in a sleeve 42 under the action of a pin 44 and groove 43. The slit width is adjusted by moving the sleeve 42 in an axial direction and varying the distance apart of the pins 47, 48 by the coaction of the pin 44 and groove 43. When the release knob is depressed, the disc 46 breaks the connection between the coupling pins 47, 48. In a modification, the coupling pins are replaced by a double-ended spring-pressed pin-and-slot engagement of the driving disc with the shutter drive and shutter adjustment. The resistance adjusted is connected in a circuit including a photo-electric cell, a resistance connected to the objective diaphragm adjustment and an instrument in which the pointer is brought to the zero position. The Specification as open to inspection under Sect. 91 also describes the connection of a sliding contact to the iris diaphragm positioning ring and to the resistance in the circuit. The lead goes also to the measuring instrument mounted on the camera body. This subjectmatter does not appear in the Specification as accepted.