Switchable format 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 advance mechanism for engaging the perforations and for advancing the film frame-by-frame past an aperture in the projector;
• a pair of constant speed sprockets, one on each side of the aperture and the intermittent advance mechanism, having teeth for engaging the perforations and for moving the film through the projector in cooperation with the intermittent advance mechanism;
• a first motor having a rotational output for rotating the pair of constant speed sprockets;
• a second motor having a rotational or reciprocating output for actuating the intermittent advance mechanism;
• a third motor having a rotational output for rotating a shutter;
• a first controller that controls and coordinates the rotational output of the first motor, wherein the first controller is adapted to change or maintain the rotational output of the first motor, without substantially interrupting projector operation, to thereby change or maintain the rotational speed of the pair of constant speed sprockets 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;
• wherein the first controller also controls and coordinates the third motor and is responsive to a trigger signal for changing the output of the third motor and thus the rotational speed of the third motor, wherein the trigger signal indicates when the film in the projector changes from a mode in which the film advances at a first predetermined frame-rate to a mode in which the film advances at a second predetermined frame-rate;
• and
• a second controller which, in response to the trigger signal, controls the output of the second motor to execute a first indexing film advance, the span of which is determined by the frame-heights of the outgoing and incoming film formats, followed by an output of successive film advances with a span corresponding to the frame-height of the incoming 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 and an intermittent movement device for moving the film through the projector;
• motor means for rotating the sprockets and actuating the intermittent movement device at selected speeds and for intermittently positioning the film frame-by-frame past an aperture in the projector;
• control means for controlling the motor means and for either maintaining or changing the movement of the intermittent movement device, the rotational speed of the sprockets and the movement of the film based on the format of the film in terms of the number of perforations spanned by each frame on the film and based on the projection frame-rate in terms of frames per second;
• and
• control means for controlling the motor means and for providing a first indexing move, based on the frame-heights of the outgoing and incoming film formats, to provide proper framing of the incoming film format.

A method of transporting film through a projector having a pair of constant speed sprockets that engage perforations on the film to advance the film at a uniform rate and an intermittent advance device to advance the film frame-by-frame past an aperture in the projector, wherein a first motor has a rotational output that rotates the constant speed sprockets, a second motive element has an output that positions the intermittent advance device, and a third motor has a rotational output that rotates a shutter, comprised of:

• determining the incoming film frame-height in terms of the number of perforations spanned by each frame on the film;
• determining a first indexing move based on the frame heights of the outgoing and incoming film formats;
• determining the film frame-rate in terms of frames per second passing through the aperture;
• controlling the rotational output of the first motor and the rotational speed of the constant speed sprockets based on the film format;
• controlling the output of the second motive element and the positioning of the intermittent advance device based on said first indexing move and the incoming film format;
• and
• controlling the output of the third motor and also the movement of the intermittent advance device based on the film frame-rate.