Importance

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Abstract

A device is described for compensating for the movement of a cinematographic films through a camera or projector. By using the device, so intermittent film motion through the gate of the camera or projector can be dispensed with and the film can be moved continuously therethrough the camera or projector. The invention lies in the use of a plurality of inverting reflectors typically Amici prisms (70) moving in the same direction as the film (20) but at one half the speed of the film. The path of the prisms (70) is determined by a straight line segment (74) of a track (72), the straight line segment (74) being parallel to the direction of movement of the film (20). By illuminating the film over a width of at least one and a half frames using a condenser lens (18) so a number of partial images are obtained which are reconstituted in the optics so as to form in the projected image a composite frame which in general will be made up of two or three images of frame parts from two or three adjoining frames. Different devices for achieving the same end comprise a helically grooved drum formed with a 90.degree. included angle helical groove having a mirrored finish, an array of prisms mounted on a caterpillar track part of which is straight and arranged parallel to a straight film path, a disc having corner cube indents or optical roofs formed in a plane surface thereof and circularly arranged therearound, and a disc having slots therein and prisms slideable within the slots with a guide arranged to extend tangentially so as to interact with plane faces of the prisms to cause the latter to be constrained to move in a straight line over an appropriate part of the rotation of the disc.

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First Claim