| 摘要 |
For position-correctly stopping a film which is provided with film frames and can be moved forward or backward by a drive mechanism, on the film there are provided markings which are detected and evaluated by a detector device. The detector device is arranged at a predetermined distance ahead of the optical axis of the film trap. The selected film frame is moved in fast mode to the detector device by means of a drive mechanism influenced by a control circuit. Upon detection of a selected film frame marking in the detector device, the drive mechanism is switched over for reverse film running and the film with the selected marking, which continues to be moved on account of the inertia of the system, is moved back in fast mode in front of the detector device. After renewed detection of the film frame marking, the drive mechanism is switched over to slow mode. When slow mode is switched on, a film-length pulse generator is activated, the pulses of which are read in in a memory device in a manner similar to a shift register and are compared with a pulse comparison value for the distance between detector device and optical axis. During the slow mode, any further markings detected by the detector device are read in and their position is determined.
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