The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 08, 2000
Filed:
Aug. 10, 1998
James Brian Vrotacoe, Rochester, NH (US);
Edward Ellis Urquhart, Northboro, MA (US);
Heidelberger Druckmaschinen AG, Heidelberg, DE;
Abstract
An apparatus and method which reduces solid mottling in an offset printing press. One or more form rolls having a hard elastomeric outer surface, in the range of approximately 50-100 Shore A durometer hardness, preferably approximately 60-90 Shore A durometer hardness, are used to transfer ink to the plate cylinder. The use of a form roll of this type ensures a smoother application of ink to the plate cylinder, which in turn ensures smoother ink application to the blanket cylinder and printed web. If more than one form roll is used, it is preferable that, at a minimum, the final form roll, i.e., the last form roll the plate cylinder contacts in the direction of rotation, be a hard elastomeric form roll. In another aspect of the present invention, the form rolls can be made of a convex shape along their axial length, such that the diameter of the form rolls at their axial center is larger than the diameter of the form rolls at their axial ends. This is done to ensure proper contact between the form rolls and the plate cylinder. The present invention also encompasses a method of printing which reduces solid mottling and consumes less ink than in the prior art for an equivalent optical density.