The disclosure relates to an improved form of vacuum-operated printing cylinder for a printing press, providing a practical means for holding the printing plate on the cylinder by vacuum alone, without requiring separate adhesive means and/or supplementary mechanical devices for clamping the plate. In...http://www.google.com.hk/patents/US4005653?utm_source=gb-gplus-share專利 US4005653 - Vacuum cylinder for printing presses
