Patent GB-1014632-A (GB)
Title: Photographic camera
IPC: G03B7/12
Filed: 1961-12-04
Abstract: 1, 014, 632. Photographic cameras. VOIGTLANDER. A.G. Dec. 4, 1961 [Dec. 3, 1960], No. 43372/61. Heading G2A. In a photographic camera having a built-in photo-electric exposure meter, the pointer position of which is explored by a feeler device which thereby suitably adjusts the camera lens diaphragm, means are provided in gearing between the feeler member and the diaphragm setting member so that the feeler member can carry out an additional movement into an initial position outside the range of deflection of the pointer and beyond the range of the open position of the diaphragm coupled to the feeler. As shown in Fig. 1, the fully open position of the diaphragm attained when the setting ring index abuts the fixed stop 17 corresponds to an opening ¢ stop larger than the objective aperture which determined the effective maximum diaphragm aperture and is indicated by the index A<SP>1</SP> on the diaphragm setting ring scale 18 and by the index A on the meter scale 4. On operation of the camera release, a spring drive 12 moves the feeler 9 in the direction 140 until the feeler emerges and clamps the meter pointer 2 as described in Specification 878,797. Meter scale 4 is shown as having two zones 6, 7 indicating lighting conditions in which an exposure cannot be made satisfactorily. In the rest state the feeler lies opposite point C and in the absence of illumination the meter pointer lies at the zero point B in zone 6. When the feeler 9 moves in search of the needle 2 which is in the zone 5, ring 14 is rotated clockwise simultaneously by the drive 12. In the feeler movement C-A there occurs not only take-up of the lost motion movement of abutment 22 relative to abutment 23, during which the spring 15 between the rings 14, 16 is allowed to contract, but also allowance for play in the transmission. When, after an exposure has been made, the film is wound on, the spring drive 12 is rewound, returning the feeler to the position C and the diaphragm setting ring 16 to its fully open position determined by the stop 17, ring 16 being driven from ring 14 by the spring connection 15, whereafter further movement of ring 14 stretches the spring 15 and separates the abutments 22, 23. Play in the transmission is taken up by the feeler remaining initially stationary on movement of the ring 14. In an alternative arrangement, Fig. 2, the additional movement of the feeler 9 is provided by a toothed gear system with a transmission ratio which changes during movement of the feeler, Diaphragm setting ring 16 and feeler driving gear 300 are driven directly by spring drive 12. The teeth of gear 300 are interrupted so that, when the feeler is in a position outside the fully open position of the diaphragm, the gear 300 is out of engagement with a gear 301 meshing the feeler-carrying gear 19, but a lever 303 secured to gear 300 engages in a notched disc 304 secured to the gear 301. In a further arrangement, (Fig. 3, not shown), the additional movement is provided by axial displacement of a worm in the gearing, the worm being carried by a shaft axially displaceable against a spring and carrying a cam disc which engages a fixed pin to displace the shaft when the feeler is beyond the open position of the diaphragm setting range.