Large media proportional copying system

Abstract

A copying system with a large document feeder for making large copy sheet (or web) media copies by moving the document past an optical scanning slit at a preset speed proportional to the speed of the imaging surface, and transferring the image onto a selected large copy media, with an easily correctable image size. The disclosed system provides for accurately controlling and adjusting the size of the copy image relative to the document image, by controlled adjustment of the magnification or reduction without requiring anamorphic or other lens changes. It is accomplished by making a test copy of the document onto the selected large copy media in the copier; measuring the dimensional change in the image on that copy media relative to the document image, in the direction of movement; deriving a simple numerical correction factor corresponding to the measured dimensional change; entering the correction factor into a variable speed control for the large document feeder to reset the speed of movement of the document past the optical scanning slit by an amount proportional to the correction factor, to provide a corresponding image reduction or magnification dimensional change of the copy image; and making subsequent copies on that media with the document moving past the optical scanning slit at the reset speed. The correction factor derivation comprises a simple calculation also including the approximate overall length in the movement direction of the test copy media or the document, and may be derived with a simple numerical table. The system can provide an exact size copy image of the document image by compensating for varying dimensional changes of different copy media in the fuser, etc., or a selectable image size change. Different selectable preset nominal (initial, but resettable) correction factors for various copy media are desirably provided.