Film tensioning and controlling transport mechanism for a cinematograph film projector. The film take-up mechanism has a torque motor drive separate from the projector mechanism drive motor. The torque motor is energised first to tension film before the projector drive motor is energised. The torque motor is first energised with a series temperature-sensitive resistor so that torque, and film-tension, increases before the projector mechanism starts up. Film between the projector mechanism and the take-up spool is formed into a loop over a movable roller, which is spring-tensioned in the loop-lenghtening direction but is restrained by a dashpot in the loop-shortening direction. Film-tension reduces the loop length, but the projector drive motor is energised before the whole loop is taken up.
展开▼
