Method and system for compensating for paper shrinkage and misalignment in electrophotographic color printing

A system for controlling the alignment of images successively printed on a sheet of print media which comprises:

• a. means for printing a first image on a sheet of paper,
• b. means for fusing said first image into said sheet of paper and thereby producing a contraction or expansion of said sheet of paper and a shift in the position or orientation or both of a predetermined print area thereon with respect to a predefined size, position and orientation of a reference print area,
• c. means for comparing the position and size of said fused print area with the position and size of said reference print area for thereby generating one or more error signals indicative of the expansion or contraction of said fused print area with respect to said reference print area, and
• d. means connected to said comparing means for processing said one or more error signals in such a manner as to cause each successively printed single color image to be physically aligned on said print media with each preceding printed image.

A method for controlling the alignment of color images successively printed on paper or the like which comprises the steps of:

• a. providing a reference area on a print medium, such as paper, with reference dimensions, positions and orientation, respectively of X, and Y, and x, y, and .THETA., wherein Y is defined as the original and preferred direction of paper motion, X is defined as the direction of paper width perpendicular the Y direction, x and y define the coordinate positions of one corner of a sheet of paper, and .THETA. is the skew angle of the paper with respect to the Y direction,
• b. printing a color image in said reference area,
• c. fusing the color image into the print medium to thereby introduce a dimensional change in one or more of the original said X, Y, x, y, and .THETA. reference dimensions positions and orientation to obtain one or more new dimensions positions, and orientation of said X', Y', x', y', and .THETA.,
• d. measuring any changes between the original said X, Y, x, y, and .THETA. values and the new said X', Y', x', y', and .THETA.' values to thereby in turn generate corresponding said X', Y', x', y',and .THETA.' error signals, and
• e. processing said X', Y', x', y', and .THETA.' error signals in a closed loop feedback arrangement in such a manner as to write the next succeeding latent color image on a photoconductive drum with the new dimensions X', and Y', the new position x' and y' and the new orientation .THETA.'.

A system for controlling the alignment of color images successively printed on paper or the like which comprises:

• a. means for providing a reference area on a print medium, such as paper, with reference dimensions, positions and orientation, respectively of X, and Y, and x, y, and .THETA., wherein Y is defined as the original and preferred direction of paper motion, X is defined as the direction of paper width perpendicular the Y direction, x and y define the coordinate positions of one corner of a sheet of paper, and .THETA. is the skew angle of the paper with respect to the Y direction,
• b. means for printing a color image in said reference area,
• c. means for fusing the color image into the print medium to thereby introduce a dimensional change in one or more of the original said X, Y, x, y, and .THETA. reference dimensions positions and orientation to obtain one or more new dimensions positions, and orientation of said X', Y', x', y', and .THETA.',
• d. means for measuring any changes between the original said X, Y, x, y, and .THETA. values and the new said X', Y', x', y', and .THETA.' values to thereby in turn generate corresponding said X', Y', x', y',and .THETA.' error signals, and
• e. means connected to said measuring means for processing said X', Y', x', y', and .THETA.' error signals in a closed loop feedback arrangement in such a manner as to write the next succeeding latent color image on a photoconductive drum with the new dimensions X', and Y', the new position x' and y' and the new orientation .THETA.'.