Patent GB-769081-A (GB)
Title: Improvements relating to photographic shutters
IPC: G03B7/00
Filed: 1955-05-18
Abstract: 769,081. Photographic shutters. DECKEL, H, and DECKEL. F.W. May 18, 1955 [May 19, 1954], No. 14356/55. Class 98(1) In a photographic shutter, the exposure time setting member and the diaphragm settingmember are releasably coupled by a member connected to one of the members and movable in the direction of the optical axis to engage the other member, the coupling member being formed as a coupling ring preferably coaxial, with the setting members. As shown in Figs. 1 and 2, a base-plate 14 carrying a forwardly extending lens tube 16 is mounted within a shutter casing 10 carrying a rearwardly extending lens tube 12. The diaphragm and shutter blades (not shown) are arranged in known manner in the space 18 between the base-plate 14 and the rear wall of the shutter casing 10. The annular space 20 witbin the shutter casing 10 accommodates shutter drive means of known construction. A shutter speed setting ring 22, mounted for rotation about the front lens tube 16 in the front part of the annular space 20, has a driving connection with an externally mounted actuating ring 28, which, together with the shutter speed setting ring 22, is retained in position on the shutter casing by an annular cover plate 30 and a ring member 32 screwed on tn the front lens tube 16. A release lever (not shown) and a shutter setting lever extend from the rear of the shutter casing. A cap-shaped graduated ring 36 is mounted between the shutter speed setting ring 22 and the actuating ring 28 and is connected to the ring 22. The ring 36 bears a shutter speed setting scale 42. A cap-shaped diaphragm setting member 46 is mounted for rotation on the rear surface of the.shutter casing 10. A coupling ring 48 surrounds the shutter casing and is slidably mounted on the cylindrical portion of the graduated ring 36. Coupling ring 48 has formed therein a radially inwardly projecting coupling tooth 50 (see also Fig. 3) which is engageable with any one of a number of coupling slots formed in the rear end face of the graduated ring 36. A key 54 formed on the inside of the coupling ring 48 engages a complementary groove 56 in the diaphragm setting member 46 so that the coupling ring 48 may slide axially with respect to member 46, but is rotatable therewith. This enables the coupling tooth 50 to be withdrawn from engagement with one slot 52 against action of a wavy annular spring 66, and to be engaged by another slot 52. Coupling ring 48 bears a scale 58 of diaphragm stops which is arranged opposite a shutter speed setting scale 42 on the member 36. Thus the coupling ring 48 may be moved back, turned until a selected pair of values on the scales 42, 58 are opposite each other. and then released. Either the actuating ring 28 or the coupling ring 48 may then be rotated to bring any required equivalent combination of shutter speed and diaphragm aperture opposite a mark 62 on the fixed part of the camera body. The tooth 50 and the notches 52, instead of being square as shown in Fig. 3, may be of triangular form. In an alternative the tooth is formed on the ring 36 and the notches are formed on the ring 48. In this case, a grip is provided on the coupling ring 48.having a sloping surface whereby. during rotation of the coupling ring 48, the user's fingers always exert a slight axial force on the ring to maintain the coupling device in engagement. In a further modification, the coupling ring 48 is slidable on and keyed to the diaphragm setting member 46, instead of to the ring 36. Further, the coupling ring 48 may bear an index mark which may be adjusted with respect to a scale of light values formed on the ring 36.