Patent GB-949847-A (GB)
Title: Photographic diaphragm-shutter
IPC: G03B7/12
Filed: 1960-09-30
Abstract: 949,847. Photographic cameras, shutters for. AGFA A. G. Sept. 30, 1960 [Oct. 3, 1959], No. 33728/60. Heading G2A. A photographic diaphragm-shutter comprises pivoted shutter blades which act as diaphragm leaves, said shutter including means for variable aperture and shutter speed setting by which the shutter blades can be prevented from opening to expose an aperture greater than required for the prevailing light value at the set shutter speed, said means providing for simultaneous aperture reduction and shutter speed increase to take into account light value increase. The shutter shown in Fig. 1 comprises blades 7 operated in known manner by rings 3, 4, loaded by springs 8, 9 and initially held by means of lugs 11,10 which engage pin 38. When a setting lever 15 is rotated clockwise a swingle 14 is also rotated to engage a pin 12 of ring 4 and to move both rings anti-clockwise, thereby tensioning springs 8, 9 and enabling lug 36 on a lever 23 to engage a recess 37 in ring 3. Therefore, when swingle 14 leaves pin 12, ring 3, but not ring 4, rotates until a lug 13 thereon engages a predetermined step on a cam 26, to open the blades by a predetermined amount. The cam 26 is positioned by a pin 33 on a lever 29 to which it is coupled, being urged against a cam 34 of a setting ring by means of a spring 31, when a pin 17 on swingle 14 is moved away from cam 32 on lever 29. The impact of lug 13 on cam 26 causes lever 25 and lever 23, on which it is mounted, to move forward and enable the lug 36 to release ring 3. Ring 3 rotates to close the blades until its lug 11 engages lug 10 on ring 4. When lever 5 and swingle 14 are to be returned by spring 18 to their initial positions pin 17 returns lever 29 to its initial position thereby removing by means spring 35 lever 25 from the path of lug 13 so that both rings are rotated by springs 8,9 until lugs 10, 11 abut pin 38. The variation in the distance moved by ring 4 to open blades causes a variation in the exposure time. The swingle 14 may be replaced by a setting lever and a release lever. Fig. 6 shows a shutter which may be controlled by a light meter 128 or by a "flash" setting means. For setting by the light meter: When operating slide 115 is depressed a lever 125 is pivoted and moves a stop 124 thereon away from a lever 116, which carries the cam portion 126, so that it can be moved by a spring until one of the steps of a cam 127 engages the light meter pointer 129, thereby setting cam 126. Simultaneously a pawl 144 on lever 115 moves both blade rings by means of a lug on ring 104, to tension their springs 108, 109. The operation of the various parts is then similar to the above shutter. Allowance can be made for the film sensitivity by rotating a knob 135 and thereby rotating a knob 123 and pointer 129 by a predetermined amount. During this shutter operation a setting ring 151 is arranged with a mark A on a scale opposite an index 157. For flash exposures the setting ring is rotated so that index 157 moves over a scale 156 of light values and this varies the position (a) of a stepped cam 159 on the ring relative to a follower pin 164 on the lever 116 to vary the shutter diaphragm aperature and (b) a cam 158 which, through lever 152, moves the pointer 129 out of the path of lever 116. A third cam 160 controls, by means of a pin 168, a lever 154, on which another lever 155 is pivoted so that for flash exposure lever 155 is situated between a pin 165 on lever 116 and a lug 173 on blade ring 103. Thus, when blade ring103 is released for its blade closing movement lug 173 moves, through lever 155 and pin 165, the stepped cam 126 from the path of lug 114 so that for a time both blades rings move simultaneously and the shutter blades are kept open. The electronic flash apparatus may be operated by movement of lever 119 which closes the contact and a second contact may be connected in series with the first and be subsequently closed by means of slide 115. The shutter blades instead of being of the type shown may be arranged as for an iris diaphragm, i.e. they are never completely closed and require a cover blade. The shutter of Fig. 12 has only one blade ring 505, which is moved to and fro by links 502, 503 controlled by master member 501. A swingle 502 is pivoted at 516 and is fixed to link 502 but has a slot 507 in which a pin 506 on link 503 engages. The position of the pin in the link controls the shutter aperture and speed. The pin also engages a slot in a lever 509 which is pivoted at 513 so that on moving a slide 510 and therefore lever 509 downwards pin 506 is moved in slot 507 until a cam 511 engages a light meter pointer. A projection 522 on rod 510 releases the master member 501. A lever 517 is moved by lever 509 a variable distance into the path of a pin 521 and thereby the shutter speed is further controlled.