Details:
Summary:
This study examined the color uniformity of six electrophotographic press systems across a single printed form in comparison to the color uniformity of a sheetfed lithographic press and the color uniformity of an inkjet color proofing device. The hypothesis of the study was that the electrophotographic presses would have color uniformity equal to that of a lithographic press. The study supported this hypothesis for one of the electrophotographic presses in the study with four of the other presses being close. One electrophotographic press in the study had significantly worse color uniformity than all the others. The inkjet proofing device had superior color uniformity compared to any of the other presses in the study, including the lithographic press.
It was found that the colors with the lowest uniformity for the electrophotographic presses were lighter than the least uniform colors for lithography. The colors of lowest uniformity for both electrophotography and lithography were similarly low in saturation. The colors of lowest uniformity for the inkjet proofer were notably lighter and more saturated than the least uniform colors for either lithography or electrophotography.
Analysis of the unprinted paper patch showed that the electrophotographic presses typically distributed tiny toner particles on these areas. Furthermore, some of the electrophotographic presses imaged small yellow dots on the unprinted substrate as well.
Examination of the star targets showed the resolution of lithographic printing to be substantially better than any of the electrophotographic presses. One electrophotographic press printed the black star target with three colors rather than only solid black. Some of the electrophotographic presses produced the solid star target images as screened images. The resolutions of the electrophotographic presses were commonly higher than the resolution of the inkjet proofing device that was used as a reference.