| 摘要 |
A motion picture projector having selectively operable means for intermittently moving film through a projection gate in either forward or reverse directions and for continuously moving film through the gate for rewind operation includes a device for advancing film between a supply roll and the gate in forward projection, reverse projection and rewind modes of operation of the projector. Film is advanced by the device through a channel defined by at least one rotatable roller and wall means spaced apart sufficiently to permit an excess of film to build up ahead of the gate. The channel defining means may be coated with a high friction material so that during forward projection when film is pushed into the channel from the supply roll by a tendency drive mechanism, contact between the film and the high friction material coating prevents movement of more film into the channel by the tendency drive than is withdrawn from the other end of the channel by the intermittent film moving means. During reverse projection operation of the projector, contact of the film with the high friction material attenuates the force applied to the film by the tendency drive and prevents that force from reaching the film in the gate. The force attenuating effect is reduced during threading and rewind operation by permitting the roller to be rotated by the film passing thereover.
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