Intermittent mechanism

An intermittent mechanism or intermittent movement is a device or movement which regularly advances an object, web, or plastic film and then holds it in place. This process is commonly used in industry and manufacturing.

This motion is critical to the use of film 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.