Forward-reverse multi speed film transport mechanism

Abstract

The disclosure relates to a forward-reverse and variable speed film transport mechanism for use in a motion picture projector. The mechanism includes an integrally formed multiple bladed shutter and up-and-down cam which are rotatable in unison on a driven shaft and an in-out cam having a plurality of surface dwelled concentric cam tracks which is rotatable about a fixed axis in response to the rotation of the shutter and up-and-down cam. The mechanism also includes a shuttle having at least one tooth for engaging the perforations of the film and a first cam follower communicating with the up-and-down cam for causing the tooth to travel in a forward direction through a predetermined stroke and in a reverse direction through a predetermined stroke. The mechanism further includes a second follower coupled to the shuttle and communicating with the dwelled cam tracks and arcuately displaceable about the fixed axis between a first and second position so that when in the first position, the second follower causes the shuttle tooth to engage the film perforations during the forward stroke and to disengage the film perforations during the reverse stroke for forward film transportation, and when in the second position, the second follower causes the shuttle tooth to engage the film perforations during the reverse stroke and to disengage the film perforations during the forward stroke for reverse film transportation. The second follower is also radially displaceable for communicating with selected one of the dwelled surface cam tracks to vary the frequency of shuttle tooth engagement with the film perforations and to thus vary the film transportation rate.