Interlock (cinema)
Interlock is a projection system in cinemas in which several cinema halls can be used with one and the same film copy. The individual film projectors in the cinema halls have synchronous motors , so that even running is guaranteed. So-called compensation gallows are installed to compensate for small fluctuations .
The copy is unwound from the film platter, guided through the first film projector via pulleys , passed over further rollers to the second (and possibly third, or more) projector and then returned to the film platter for winding.
There are also systems that synchronize themselves via the frequency of the supply voltage of the projectors.
A disadvantage of these systems is that if one of the projectors fails during a performance, all other projectors that are in interlock mode cannot be used either.
Film plate system with three plates: the top is unwound, a second film is wound in the middle, and right at the bottom it is wound up
Various pulleys, over which the 35 mm film (gently, only the perforation is in contact) is guided through one or more projection rooms
