Patent ID: 6985261
Filing Date: 2006-01-10
Classification: G03F,H04N

Abstract:
1. An apparatus for imaging a flexo sleeve, the apparatus comprising: a flexo sleeve mounted on a rotatable drum, the drum and sleeve combination having a seam at a seam location; a laser output scanner oriented to direct one or more imaging laser beams to the surface of the flexo sleeve at one or more corresponding focal spots, the laser output scanner including for each laser beam: a fast scan motion actuator to rotate the drum relative to the one or more laser beams; a slow scan motion actuator to provide relative motion between the focal points of the one or more laser beams and the sleeve surface in a slow scan direction parallel to the axis of rotation of the drum; and a controller receiving the image data and coupled to each modulator, the fast scan motion actuator, and the slow scan motion actuator, wherein the controller couples image data to each modulator and compensates for artifacts at the seam while exposing the flexo sleeve at a speed substantially the same as conventional spiral advance imaging with no seam compensation, wherein the image data is screened using a screen that diminishes the visibility of artifacts at the seam location, and wherein the screen includes pixel displacements in the slow scan direction, the pixel displacement dependent on the distance in the fast scan direction from a starting position, such that imaging using the pixel-displaced screen with spiral advance substantially corrects seam artifacts.