How Movie Projectors Work

What is a Movie Projector?

A movie projector is a device that continuously moves film along a path so that each frame of the film is stopped for a fraction of a second in front of a light source. The light source provides extremely bright illumination that casts the image on the film through a lens onto a screen.

There are four major groups of parts that make up a projector:

  • Spool assembly (cambers, sprockets, claw, motor, platter)
  • Lamp assembly (bulb, condenser, fan, mirror)
  • Lens assembly (lens, aperture gate, shutter)
  • Audio assembly (optical and digital readers, infrared LED)

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In the following sections, we'll look at the first three assemblies. For information on the audio assembly, check out How Movie Sound Works.