Intermittent mechanism
（重定向自Intermittent movement）
![](/Images/godic/202501/20/Geneva_mechanism_6spoke_animation1625.gif")
![Animation of a rotating shutter. The film is transported one frame when the shutter is blocking illumination of the film.](/Images/godic/202501/20/Moviecam_schematic_animation1625.gif")
![Film advance mechanism in the Soviet Luch-2 8mm film projector, based on a Reuleaux triangle.](/Images/godic/202501/20/Luch2_greifer1625.gif")
The intermittent mechanism or intermittent movement is the device by which film is regularly advanced and then held in place for a brief duration of time in a movie camera or movie projector. This is in contrast to a continuous mechanism, whereby the film is constantly in motion and the image is held steady by optical or electronic methods. The reason the intermittent mechanism "works" for the viewer is because of a phenomenon called persistence of vision.