| 摘要 |
The invention relates to a circuit arrangement for controlling film advance in photographic cameras, which for the preferred use of film cartridges are constructed with electrically readable coding of the film length. The aim and object of the invention is to improve known devices of this type by means of a circuit which despite a low degree of complexity simplifies the film advance up to the rewound state and ensures that damage to the film and winding it back too far are excluded. In accordance with the invention, this object is achieved when use is made of a coding circuit for the maximum number of frames which can be read off electrically from the film cartridge as well as for pulses emitted by a frame counter independently of the direction of film movement, at the outputs of which there is connected a logic circuit for processing signal levels which characterise the maximum possible frame number, the actual frame number, twice the maximum frame number, the zero setting of the frame counter and fixed numbers and which forms the control element for initiating film rewinding when a maximum frame number has been reached, and for stopping rewinding when twice the maximum frame number recorded by the frame counter is reached. <IMAGE>
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