Abstract: The invention refers to a method of shortening the closure time of shutters in cinema projectors of the type in which film is intermittently advanced one frame at a time into registry with an image window in the projector, and wherein each time the film is advanced a shutter in the projector closes the image window during the time that the film is being advanced. According to the invention, an optical compensation of the film motion is effected by determining the rate at which each image of the film begins and ends, respectively, its advance into registry with the image window of the projector, generating a control signal proportionate to the rate, and positioning between the image window and the associated projection screen a movable plane-parallel plate which is adjsuted by the control signal to shorten the closure time of the image window during each film advance, thereby to increase the luminous efficiency factor of the projector.

Abstract: Installation for driving and positionally controlling a film 7, including a device for etching of the film by a LASER beam F. The displacements of laser beam F are controlled by an X-Y optical deflection system S, this system itself being under the control of a computer including subtitles in its memory. This installation also includes: a motor M controlled by the said computer and capable of setting the film 7 in continuous motion, possibly with interruptions, however, for etching of the subtitles; a sprocket drive mechanism 1 coupled to the motor M for driving the film; a device T for memory-storage of the defects in concentricity of the drive mechanism 1; and a system V for compensation between the device T and the optical deflection system S, for correcting the position of the etching LASER beam F, depending on the defects, so that each subtitle is in exactly the desired position with respect to the relevant image of the film, notwithstanding the defects, which are inherent in any drive mechanism.

Abstract: When used for projecting or editing motion picture film the optical rectification apparatus produces a stationary image of a frame of a moving film and a succession of superimposed stationary images from successive frames of the moving film. The apparatus employs an optically transmissive hollow cylindrical prism having a cylindrical external surface and an internal surface consisting of a number of facets. Light from the moving film is passed outwardly through the wall of the rotating prism and through a stationary plano-concave cylindrical lens positioned with its concave surface adjacent the external surface of the prism, but spaced slightly from it. The prism is connected to the same shaft as the film sprocket wheel resulting in an isotransport system in which the prism rotates in synchronism with movement of the film to deviate the light through an angle sufficient at each instant to compensate for the angular deviation of the light caused by movement of the film.