Patent GB-773003-A (GB)
Title: Improvements in or relating to photographic shutters having coupled expesure meters
IPC: G03B7/06
Filed: 1955-06-03
Abstract: 773,003. Photographic cameras with exposure meters. GAUTHIER GES., A. June 3, 1955 [June 5, 1954], No. 15991/55. Class 98(1) [Also in Group XL(b)] In a photographic shutter having a coupled exposure meter arranged externally of the shutter casing, a flexible motion-transmission device operating on the principle of a Bowden cable is provided for operatively connecting the shutter speed member and/or the diaphragm setting member of the shutter to the exposure meter. As shown in Fig. 1, a photo-electric exposure meter has a housing 1 with a honeycomb window 2 for the admission of light. A setting disc 4 is pivoted about a stud 3 on the housing, and is fast with a gear wheel 5 meshing with a gear wheel 7. A spring 8 acts on a stop 7a on the wheel 7 to urge the setting disc 4 to rotate in a clockwise direction. A spindle 19, which may bear against the stop 7a, slides in a socket 10 fixed to the exposure meter housing. A cable, similar to a Bowden cable, may be fixed to the socket 10 as by a bayonet connection, and a return spring within the cable urges the spindle 19 into contact with stop 7a. The other end of the flexible cable is connected to a between-lens shutter mechanism as shown in Fig. 4. The shutter speed setting ring 21 of the shutter has an opening therein one edge 21a of which is stepped to form a cam surface for co-operation with a control pin 22 connected to the shutter speed determining mechanism (not shown). A cam slot 21b of correspondingly stepped formation is formed in another part of the shutter ring 21, and cooperates with a pin 25 carried on a lever 23 pivoted at 24 to the shutter casing. As the shutter speed setting ring is rotated to set a particular shutter speed, the position of the lever 23 varies. A sleeve 26 is formed on the shutter casing, and is formed with means whereby the flexible cable can be connected to it. For example, the sleeve may have a conical thread for receiving the corresponding 'thread on the outer sleeve of the cable. The inner member of the flexible cable is spring urged forwardly to engage a pin 27 sliding the sleeve 26, causing it to bear against the lever 23. Thus movements of the lever corresponding to the shutter speed setting are communicated to the inner member of the flexible cable, and thence to the spindle 19. Movement of this spindle causes a rotation of the setting disc 4 of the exposure meter, so that the shutter speed set is indicated on a scale 29 of the setting member 4 by an index mark 28 on the body of the exposure meter. A ring 30, which is rotatably mounted on the setting disc 4, carries a scale 31 of diaphragm apertures and also has a window 30a overlying a film speed scale 32 on the setting member 4. The disc 30 is so adjusted that the speed corresponding to the film in use is visible through the window 30a. The shutter speed setting disc 21 is then adjusted, with corresponding movement of the setting disc 4, until the pointer 34 of the photo-electric exposure meter indicates on the scale 31 the diaphragm aperture set on the camera. A connecting scale 35 facilitates this setting. Alternatively, a desired shutter speed may be set, and the diaphragm stop is read off from the scale 31. The camera is then adjusted accordingly. In alternative arrangements, the setting disc may be coupled to the diaphragm setting member instead of to the shutter speed setting member, or to an element which is connected to both the shutter speed setting member and the diaphragm setting member in accordance with the light value. The form of the shutter setting disc shown in Fig. 4 may be modified by forming the cam surface 21a as a smooth cam surface, instead of a stepped cam surface, and by forming the slot 21b as a smooth slot, in this case part of the cam surface 21a, and the corresponding part of the slot 21b, may be formed as parts of a circle, so that, when the shutter speed setting ring has been turned to the position for a "bulb" exposure is reached, the shutter setting,ring 21 may be further rotated without effecting the shuter setting. Such rotation, however, allows the shutter speed setting ring 4 to be rotated so that the required time of exposure may be indicated, even though it is beyond the range of shutter speeds which can be set on the ring 21. The cam slot 21 can be replaced by a cam surface formed on the end surface of a cylindrical extension range, for example, on the annular shutter speed setting member.