Abstract: In a digital imaging system including an array of imaging devices that image a substrate in a lateral series of adjacent longitudinal swaths, methods and apparatus for correcting device offset and hiding between regions imaged by adjacent devices. Along the direction of imaging (i.e., the dimension along which the imaging device(s) and the substrate move relative to one another during an imaging pass), adjustments take the form of compensating increases or decreases to the normal intervals between discharges to adjacent image points. Transverse to the direction of imaging, the invention compensates for imprecise device orientation and "seam" artifacts by, first, commencing imaging with the device having the greatest offset from proper orientation, and second, as a fine adjustment, repeating at least one imaging swath to produce intentional transverse overlap between adjacent swaths.

Abstract: A method of reducing printing artifacts in a printing apparatus including a plurality of printing plates, each of which is produced by successive scans of an array of imaging devices wherein the printing artifacts are caused by defective operation of one or more of the imaging devices. Printing artifacts are visually minimized by staggering the imaging devices used to produce separation plates. By staggering the imaging devices, the distance between artifacts can be reduced thereby causing the artifact reproduced in the final composite image to be less accentuated.

Abstract: An apparatus and method for controlling discharge devices used to image a planographic printing plate are disclosed. Imaging information is stored in a first memory while discharge correction data is stored in a second memory. The correction data is used to vary the intervals between imaging discharges to compensate for error between the sensed position of the printing plate with respect to a writing head and the actual position. Printing artifacts are visually minimized by staggering the imaging devices used to produce separation plates.

Abstract: Printing apparatus has at least one print station including a blanket cylinder in rolling contact with an impression cylinder, a print cylinder for supporting a lithographic plate, the plate cylinder being in rolling contact with the blanket cylinder, at least one discharge source for applying an image to a plate supported by the plate cylinder, and a motor for moving the energy source relative to the plate cylinder so that when the plate cylinder is rotated, the discharge source scans a raster on the surface of the plate supported by the plate cylinder. The apparatus may be configured as an in-line or central-impression type press. A controller responsive to picture signals representing an original document repeatedly actuates each discharge source momentarily during the scan thereof so that the discharge source forms on the plate surface an image comprised of dots corresponding to the original document.

Abstract: A low cost press able to print high quality continuous tone color copies comprises a single large diameter impression cylinder rotatably mounted to the machine frame. A plurality of print stations are spaced around the impression cylinder, each print station including a blanket cylinder in rolling contact with the impression cylinder and a plate cylinder in rolling contact with the blanket cylinder, the diameters of all of said plate and blanket cylinders being substantially the same and said impression cylinder having a diameter that is the same as or an even number more than the product of the plate cylinder diameter multiplied by the number of plate stations in the press. The cylinders are all rotatably coupled together by correspondingly sized gears so that they all rotate in unison with the impression cylinder gear being composed of arcuate parallel-cut segments having identical tooth profiles.