Patent GB-1076827-A (GB)
Title: Photographic camera
IPC: G03B7/083
Filed: 1964-11-23
Abstract: 1,076,827. Shutter mechanisms. AGFA A. G. Nov.23, 1964 [Nov.23, 1963], No.47651/64. Heading G2A. In a photographic camera set for a bulb exposure and of the type in which a first shutter member (a disc 8 and a blade 6) runs down to open the shutter aperture 62 and after a delay a second shutter member (a disc 9 and a blade 7) runs down to shut the aperture, a release lever 22 is moved anti-clockwise to open an auxiliary control switch 29 and to release a pawl 18 to close a control switch 26, no current flowing since an auxiliary switch 28 is also open. This disc 8, free to rotate since the pawl 18 has been released, is prevented from running down by mechanism 57-59 while a relay is being energized. When the mechanism has caused the required delay, the first shutter member runs down and exposes the aperture 62 which remains open until a manual shutter release is liberated. The lever 22 then rotates in the direction of the arrow a closing the switch 29 and allowing current to flow, thus energizing the relay 33 after a short delay depending on the resistance of a photo-resistor 34. When the relay is energized, a pawl 51 is pivoted to release the second shutter member which runs down to close the aperture 62, the pawl also opening a switch 39 to break the circuit. For a flashlight exposure, a ring 45 is rotated thus allowing the aim 32b of a contact lever 32 to enter a recess 47, a contact 29b to meet a surface 44 and open the switch 29, and a switch 36 to rotate to cut out the photoresistor 34 and cut in a fixed resistor 35. When the lever 22 is rotated counter-clockwise, the pawl 18 is released as before and the lever 32 follows a projection 22c to close the switch 28. The first shutter member runs down after a delay, as before. On closing the switches 26, 28 the relay 33 is energized, the resistor 35 delaying building up of the field in the relay so that an exposure of about <SP>1</SP>/ 30 th second occurs before the second shutter member runs down and the interrupter switch 39 is opened. An automatic exposure is effected in the same way as a flash exposure, except that the photo-resistor 34 is used instead of the fixed resistor 35. In another embodiment Fig.2 (not shown), a multiple auxiliary control switch (71) replaces the switches 28, 29 and a capacitor (81a) is provided. Relay (80) is initially energized preventing run down of the second shutter member by rotating a pawl (97) into its path. When the manual release lever is actuated after run down of the first shutter member, the relay (80) is de-energized, pawl (97) released and the second member allowed to run down. For flash exposure a fixed resistor is now connected in the circuit delays the deenergization of the relay (80) for a suitable time to allow of an exposure. For automatic exposure the photo-resistor (81) is used as for the bulb exposure. In a still further embodiment Fig.3  (not shown) two relays (100), (101) are used for liberating the first and second blade driving discs 8, 9 respectively. Other forms of shutters, apart from the blade shutters shown, may be used. The invention is not restricted to a flywheel retarding mechanism 57-59. The manual changeover control may be arranged as a diaphragm setting means.