Film clamp for flattening image frames in a scanning gate

A method of clamping the longitudinal and transverse edges of a filmstrip image frame with respect to a fixed aperture of a stationary base, said fixed aperture defined by longitudinal and transverse opening edges formed in a surface of said stationary base and spaced apart to allow scanning of the filmstrip image frame therethrough, in a flattening mode when filmstrip transport is halted, and, in a transport mode, of unclamping and allowing transport of the filmstrip past the fixed aperture through a transport gap by a filmstrip transport mechanism, said method comprising the steps of:

• pivotally mounting and supporting a pair of spaced apart, longitudinally extending, clamping elements with respect to a movable carrier on the free ends of a respective pair of support arms in a retracted position extending toward, while spaced apart from, said base surface and forming said transport gap through which said filmstrips are transported longitudinally in said transport mode by said transport mechanism;
• supporting a pair of spaced apart, transversely extending clamping elements with respect to said movable carrier in a retracted position spaced apart from said surface of said stationary base sufficiently to avoid contact with said filmstrips transported longitudinally in said transport mode by said transport mechanism;
• in said transport mode, operating said transport mechanism to advance said filmstrip image frames longitudinally through said transport gap in relation to said fixed aperture;
• and,
• in said flattening mode, moving said carrier and said longitudinally and transversely extending clamping elements from said retracted position into said transport gap and into a contact position with the longitudinal and transverse edges of said image frame, and in the course of such movement into the contact position:
• applying normal compressing force through the longitudinally extending clamping elements to compress the longitudinal edges of said filmstrip image frame against said surface of said stationary base;
• applying laterally directed tensioning force through the longitudinally extending clamping elements as said longitudinally extending clamping elements pivotally spread apart and move away from the longitudinal edges of said image frame to laterally tension the longitudinal edges of said filmstrip image frame apart;
• and
• applying normal compressing force through the transversely extending clamping elements to compress the transverse edges of said filmstrip image frame against said surface of said stationary base,
• whereby in said contact position said filmstrip image frame is flattened by normal compression force applied along the longitudinal and transverse edges of the filmstrip image frame and tensioned laterally by said laterally applied force as said longitudinally extending clamping elements are fully moved and spread apart transversely.

Apparatus for clamping the longitudinal and transverse edges of a filmstrip image frame with respect to a fixed aperture of a stationary base, said fixed aperture defined by longitudinal and transverse opening edges formed in a surface of said stationary base, in a flattening mode when filmstrip transport is halted, and unclamping and allowing transport of the filmstrip past the fixed aperture in a transport path by a filmstrip transport mechanism in a transport mode, said apparatus comprising:

• first and second pairs of spaced apart, longitudinally and transversely extending clamping elements, respectively;
• a movable carrier;
• means operable in said for moving said movable carrier from a retracted position to a contact position with respect to said base;
• first supporting means for supporting said first pair of spaced apart, longitudinally extending, clamping elements for pivotal movement with respect to said movable carrier upon movement of said carrier into said contact position from said retracted position;
• first biasing means for biasing said longitudinally extending clamping elements away from said movable carrier and toward, while spaced apart from, said surface of said stationary base and forming a transport path gap through which said filmstrips are transported longitudinally in said transport mode by said transport mechanism;
• second supporting means for supporting said second pair of spaced apart, transversely extending clamping elements for normal movement with respect to said movable carriage upon movement of said carrier into said contact position from said retracted position;
• second biasing means for biasing said transversely extending clamping elements toward, while spaced apart from, said surface of said stationary base, whereby said transport path gap is sufficient to avoid contact with said filmstrips transported longitudinally in said transport mode by said transport mechanism;
• means operable in said flattening mode for moving said first pair of spaced apart, longitudinally extending, clamping elements from said retracted position into said gap and into a contact position for applying compression force on the longitudinal edges of said filmstrip image frame and against said surface of said stationary base and for applying tensioning force transversely across said image frame on the longitudinal edges of said filmstrip image frame and against said surface of said stationary base;
• means operable in said flattening mode for moving said second pair of spaced apart, transversely extending, clamping elements from their retracted position into said gap and into a contact position for applying compression force on the transverse edges of said filmstrip image frame and against said surface of said stationary base,
• whereby said filmstrip image frame is flattened by tensioning and compression forces applied along said longitudinal and transverse edges of the filmstrip image frame as said clamping elements are advanced fully to their respective contact positions.