Frame-rate converting film scanner with two-dimensional solid state

Abstract

A frame-rate converting film scanner includes means for continuously advancing film at a selected frame rate and for projecting an image of the moving film onto a solid state image sensor for producing a television signal at a standard television field rate. The solid state image sensor includes: (1) a two-dimensional array of image sensing elements having a width equal to the width of the projected image of a film frame and a height equal ot the projected image of 2+X/Y film frames, where X is the projection rate of the film in frames per second and Y is the field rate of the standard video signal in fields per second, (2) a two-dimensional frame storage array, (3) an output register, and (4) a 'drain gate' disposed between the image sensing array and the frame storage array and operable in a first mode to transfer signals from the image sensing array to the storage array and in a second mode to drain signals from the image sensing array. The image of the moving film is projected on the image sensing array to produce an imagewise pattern of photocharge and the sensing array is operated to move the pattern of photocharge accumulated in the array in synchronism with the moving image. As lines of photocharge are advanced to the top of the sensing array, they are dumped by the drain gate. After a predetermined exposure time, a full frame of photocharge is rapidly transferred to the temporary storage array from the image sensing array via the drain gate. The frame of photocharge is read out of the storage array at the standard video field rate via the output register while a new pattern of photocharge is accumulated in the image sensing array. The scanning apparatus includes timing means for keeping track of the location of moving film frames with respect to the image sensing array and clocking means associated with the timing means for rapidly shifting a complete frame's worth of charge into the temporary storage array.