Patent GB-922482-A (GB)
Title: Photographic camera
IPC: G03B9/22
Filed: 1959-07-20
Abstract: 922,482. Photographic cameras. AGFA A.G. July 20, 1959 [July 30, 1958], No. 24902/59. Class 98 (1). In a photographic camera having a pivoted blade shutter, with shutter speed setting means incorporated in the objective and with shutter blades and shutter-operating mechanism combined in a unit accommodated in the camera housing, said blades and mechanism are so associated with the shutter speed setting means that the said unit is detachable from the camera without disturbing the objective, the latter being attached to the camera housing either directly or by way of an objective mount. As shown (Fig. 1) the blades 16 and operating mechanism 14 of a shutter are contained in a detachable unit which fits into a recess 24 in the base of the camera. The unit is secured in position by screws 57, and is covered by a cap 26. Before removing or inserting the unit, a pin and slot connection formed by a pin carried by a shutter speed setting ling 29 on the objective 21 and a slot 28 in the shutter speed setting disc 27 must be aligned. Fig. 4 shows the shutter operating mechanism 14 in a ready-forexposure condition. On depression of a release 46, a double-armed lever 45 is moved out of locking engagement with a recess 44 in a driving disc 41 whereby this disc is freed to run down in an anticlockwise direction through 180 degrees under loading by a main driving spring 42. The opening and closing of the shutter blades 16 as the disc 41 runs down is effected by a lever 63 which is pivoted at a normally stationary point 66, has a finger 67 engaging in a slot in a shutter blade operating disc 68 and is connected by a rod 65 to the disc 41. In order to provide for different exposure times, a retard mechanism 36 of known construction is mounted on a fixed bracket 37 with an abutment 39 thereof in the path of movement of a projection 40 on the disc 41, the retard provided by the mechanism 36 being adjusted according to the position of a setting disc 27 by way of a rotatable segment 33 in toothed engagement with the rim of said disc 27 and having a speed cam 34 in engagement with a setting pin 35 of the mechanism 36. Recocking of the shutter as the film is wound on for the next exposure is effected as follows. A disc 52 is coupled to a shaft (Figs. 2 and 3, not shown) of a known type of counting mechanism and is rotated once during each film advance. During each such rotation, by way of a link 51 and a slidably mounted rack 49, a pinion 48 is made to rotate first in a clockwise direction through 180 degrees and then in an anticlockwise direction through 180 degrees. During said clockwise rotation and by way of a nowengaged lost-motion coupling between stop 48a of pinion 48 and pin 41a of disc 41, the disc 41 is also rotated through 180 degrees in a clockwise direction, and the shutter disc 41 and spring 42 are thereby recocked. In order that the shutter blades are not opened by this cocking movement of disc 41 and rod 65, a spring-urged slide 60 is arranged to be compensatingly displaced first to the left and then to the right on its guide pins 61 by a cam disc 58 connected to disc 52. A modified shutter mechanism for a single lens reflex camera is shown in Fig. 8 in the ready for exposure condition with a spring-urged shutter blade operating disc 68a in its blade-open position for viewing, which position is defined by the engagement between a projection 100 of the disc 68a and a fixed pin 102. In this embodiment, the link pivot pin 66 of a lever 63a is guided in a slot 70 of a slide 60a and a tension spring 71 tends to draw the pin 66 to the left-hand end of this slot. In the cocked position shown, however, a projection 72 of the lever 63a is held against the tension of the spring 71 by a spring-urged latch 73. The cycle of events leading to exposure after depression of a body release 75 is as follows. As soon as lever 63a is released by latch 75, it pivots in the clockwise direction about pin 64 and by means of the engagement between lug 103 of disc 68a and tip 67 of lever 63a the shutter blades are closed. In the course of its movement, the lever 63a engages a spring-urged slide 76 and by way of a further slide 81 (in engagement with a sloping surface 80 of the slide 76) a spring-urged latch for the viewing mirror 87 is released. This mirror then pivots under spring loading (not shown) out of the path of the exposure beam and is followed after the mirror has reached its end position by a pivoted spring- urged cover flap 88. At the end of its movement, this flap engages a lever 96 which, by way of a slide 92, actuates a lever 45a to release the disc 41. The shutter mechanism then operates as in the previous embodiment. During recocking of the mechanism, discs 41 and 58 are respectively rotated through one half and one whole revolution-as before-but slide 60a is arranged to move oppositely to the previous case (i.e. right and then left), the lever 63a being re-engaged by the latch 73 during this movement. As a result, the engagement between lever 63a and lug 103 is broken for a short time while said lever moves through the position 104 and back to the shutter open position shown. If desired, however, the movements of disc 41 and slide 60a can be staggered so that positive connection between parts 67 and 103 is always retained.