The term “IOWA” relates to Image On Web Array as used in duplexing marking systems. While the present invention will be described as used in direct marking printing systems, it is equally applicable and useful in electrophotographic duplexing systems.
The use of an array of print heads in ink-jet printing is well known in the art as disclosed in co-pending application Ser. No. 11/773,549. Briefly, direct marking printing comprises ejecting ink droplets from orifices in a print head onto some type of receiving media to form a desired image. Generally, this formed image comprises a grid-like pattern of drop locations usually referred to as pixels. Often, the image resolution is indicated by the number of ink drops or dots per inch (dpi) commonly having a resolution of from about 300 dpi to about 600 dpi. The disclosure of above application Ser. No. 11/773,549 details this ink-jet process precisely and is totally incorporated by reference into the present disclosure.
U.S. Pat. No. 5,389,958, assigned to the assignee of the present application, is an example of an indirect or offset printing architecture that utilizes phase change ink. The ink is applied to an intermediate transfer surface in molten form having been melted from its solid form. The ink image solidifies on the liquid intermediate transfer surface by cooling to a malleable solid intermediate state as the drum continues to rotate. When the imaging has been completed, a transfer roller is moved into contact with the drum to form a pressurized transfer nip between the roller and the curved surface of the intermediate transfer surface/drum. A final receiving web such as a sheet of paper media is then fed into the transfer nip and the ink image is transferred to the final receiving web.
Inks usable in the present invention are like those described in U.S. Pat. Nos. 5,389,958 and 4,889,560. The disclosures of U.S. Pat. Nos. 5,389,950 and 4,889,560 are also incorporated by reference into the present disclosure. U.S. Pat. No. 5,389,958 indicates “the ink used to form the ink image preferably must have suitable specific properties for viscosity”. Initially, the viscosity of the molten ink must be matched to the requirements of the ink-jet device utilized to apply it to the intermediate transfer surface and optimized relative to other physical and rheological properties of the ink as a solid, such as yield strength, hardness, elastic modulus, loss modulus, ratio of the loss modulus to the elastic modulus and ductility. The viscosity of the phase change ink carrier composition has been measured on a Ferranti-Shirley Cone Plate Viscometer with a large cone. At about 140° C. (older version of ink, the current is 120° C.), a preferred viscosity of the phase change ink carrier composition is from about 5 to about 30 centipoises, more preferably from about 10 to about 20 centipoises and most preferable from about 11 to 15 centipoises. The surface tension of suitable inks is between about 23 and about 50 dynes/centimeters.
As noted in the above-referenced prior art patents, the usable ink also used in the present invention is in a solid phase at ambient temperature and in a liquid phase at elevated operating temperatures.
Cleaning webs for toner-using marking systems are known in the art such as those disclosed in U.S. Pat. No. 6,799,000, patent application Ser. No. 12/512,279 and Ser. No. 12/336,791. The cleaning web used in the present invention can have the same or similar compositions and forms as these prior art cleaning webs.
Duplexing marking systems are also known such as those disclosed in U.S. Pat. No. 5,991,564. All of the above patents and patent applications are incorporated by reference into the present disclosure.
While running the web (paper) in duplex or mobius mode, ink transferring from the web onto the IOWA backup roll has been observed. This creates a condition of annular streaks buildup onto the roll. The IOWA sensor which is located directly over the roll has the ability to read through the web media which results in detection of these annular streaks promoting false registration measurements into the system. Current strategy for resolution requires cleaning or replacement of the roll when this scenario occurs creating undesirable downtime to the customer and added costs.