GB926258A - Photographic camera - Google Patents

Abstract

926,258. Photographic cameras. AGFA A.G. March 2, 1962 [March 3, 1961], No. 8276/62. Class 98 (1). A camera having film-advancing means operated by an electric motor has a switch in the motor circuit actuable by the film-advancing means to break the circuit after film advance by one full frame, and a further switch in the motor circuit actuable by means other than the film-advancing means to break the circuit after a film-advancing movement has terminated, whether by a complete frame or not. In the form shown, the film is advanced by a motor 3 driven by a battery 2. After the shutter is operated to make an exposure, the switch 4 is closed to contact 5, completing the motor circuit, which advances the film by one frame, and re-sets the shutter; on completion of one film frame advance, switch 4 breaks from contact 5, closing contact 6 to short-circuit the motor. If the film were not advanced by a full frame, as might happen at the end of the film, or for some other reason such as damaged perforations, the connection of switch 4 with contact 5 would not be broken, and the battery would be rapidly discharged. Accordingly, a further switch 7, 8 is provided in series with the contact 4, 5, which in the form shown is operated by an arm 10 of the camera release lever 12, turning on a pivot 11, shown when ready to make an exposure. At this moment the contacts 7, 8 are held apart by arm 10. When release lever 12 is pressed, contacts 7, 8 are released to close together. A rack portion 15 on lever 12 engages with a pinion 16 forming part of a gear train and escapement system 26, the whole acting as a retarding mechanism. When the release lever 12 is pressed, pinion 16 rotates without entraining the rest of the mechanism, which acts to retard only the return motion of the lever. Thus contacts 7, 8 remain closed for a predetermined period while the return of lever 12 is retarded. This period is made long enough for the normal advancement of one film frame to take place. As lever 12 reaches the end of its retarded return motion, arm 10 breaks the connection between contacts 7, 8. Thus, whether the motor circuit has been broken by separation of contacts 4, 5 or not, the circuit is in any case positively broken by separating contacts 7, 8. In the arrangement of Fig. 3 (not shown), instead of a mechanical retarding mechanism, an electrical regulator is used, controlled by a governor on the motor shaft.