Switchable pulldown film projection system

In a motion picture film projector, a film projector movement for transporting film having a series of frames with images thereon, and a plurality of perforations along edges of the film, comprising:

• an intermittent sprocket having teeth for engaging the perforations and for advancing the film frame-by-frame past an aperture in the projector;
• a pair of sprockets, one on each side of the aperture and the intermittent sprocket, having teeth for engaging the perforations and for moving the film through the projector in cooperation with the intermittent sprocket;
• a first motor having a rotational output adapted to selectively rotate the pair of sprockets at a plurality of different constant speeds;
• a second motor having a rotational output adapted to intermittently rotate the intermittent sprocket;
• and
• a controller that controls and coordinates the rotational outputs of the first and second motors, wherein the controller is adapted to change the rotational output of the first and second motors, without substantially interrupting projector operation, to thereby change the rotational speed of the pair of sprockets and the intermittent rotational movement of the intermittent sprocket when the film in the projector changes from a first film format in which each frame spans a first predetermined number of perforations on the film to a second film format in which each frame spans a second predetermined number of perforations on the film, and wherein the frames of the film are recentered with respect to the aperture each time there is a change in the film format.

A film projector movement for transporting film through a projector, wherein the film has perforations along its edges and frames between the perforations, comprising:

• a plurality of sprockets that engage the film and move it through the projector;
• a motive element having a first output coupled to one of said sprockets for selectively rotating said sprocket at a plurality of different rotational speeds and a second output for intermittently rotating another of said sprockets and registering the film frame-by-frame with respect to an aperture in the projector;
• and
• a controller coupled to the motive element for controlling the motive element, wherein the controller is responsive to a trigger signal for changing the outputs of the motive element and thus the rotational movement of the sprockets, wherein the trigger signal indicates when the film in the projector changes from a format in which each frame spans a first predetermined number of perforations on the film to a format in which each frame spans a second predetermined number of perforations on the film, and wherein the frames of the film are recentered with respect to the aperture each time there is a change in the film format.

A method of transporting film through a projector having an intermittent sprocket and a pair of sprockets that engage perforations on the film and advance and register the film frame-by-frame with respect to an aperture in the projector, wherein a first motor has a rotational output that selectively rotates the pair of sprockets at a plurality of different constant rotational speeds and a second motor has a rotational output that rotates and positions the intermittent sprocket, comprised of:

• determining the film format in terms of the number of perforations spanned by each frame on the film;
• controlling the rotational output of the first motor and the rotational speed of the pair of sprockets based on the film format;
• controlling the rotational output of the second motor and the positioning of the intermittent sprocket based on the film format;
• generating a trigger signal that changes the rotational outputs of the first and second motors and thus the rotational speed of the pair of sprockets and the positioning of the intermittent sprocket, wherein the trigger signal is based on a change in the film format;
• and
• recentering the frames of the film with respect to the aperture each time there is a change in the film format.

A film projector movement for transporting film through a motion picture projector, wherein the film has a series of frames and plurality of perforations along edges of the film, comprising:

• a plurality of sprockets that engage the film and move it through the projector;
• a motive element having an output coupled to the sprockets for rotating the sprockets and advancing and registering the film frame-by-frame with respect to an aperture in the projector;
• a controller coupled to the motive element for controlling and coordinating the output of the motive element;
• and
• wherein the controller is responsive to a signal generated automatically during operation of the projector that commands the controller to change the output of the motive element when the film in the projector changes from a first format in which each frame spans a first predetermined number of perforations to a second format in which each frame spans a second predetermined number of perforations, and wherein the frames of the film are recentered with respect to the aperture each time there is a change in the film format.

A method of transporting film through a projector having a plurality of sprockets that engage perforations on the film and a motive element that has an output that rotates the sprockets and registers the film frame-by-frame with respect to an aperture in the projector, comprised of:

• determining a first format of the film in which the film has frames spanning a first predetermined number of perforations on the film;
• controlling the output of the motive element based on the first format to register and properly center the frames with respect to the aperture;
• sensing a change in film format during operation of the projector from the first format to a second format in which the film has frames spanning a second predetermined number of perforation on the film;
• and
• changing the output of the motive element based on the second format to register and properly center the frames with respect to the aperture.

A film projector movement for transporting film through a motion picture projector, wherein the film has a series of frames and plurality of perforations along edges of the film, comprising:

• a plurality of sprockets that engage the film;
• an intermittent sprocket that engages the film;
• a motive element having a first output coupled to the plurality of sprockets for rotating the sprockets and controlling loops of film on opposite sides of an aperture in the projector, and having a second output coupled to the intermittent sprocket for registering the film frame-by-frame with respect to the aperture;
• a controller coupled to the motive element for controlling and coordinating the first and second outputs of the motive elements;
• wherein the controller is responsive to a signal generated automatically during operation of the projector that commands the controller to change the outputs of the motive element when the film in the projector changes from a first format in which each frame spans a first predetermined number of perforations to a second format in which each frame spans a second predetermined number of perforations;
• and
• recentering means for recentering the frames of the second format with respect to the aperture when the film in the projector changes from the first format to the second format.