Patent Application
20050169680
The present invention generally relates to controlling gloss and differential gloss, and more specifically, controlling gloss and differential gloss while maintaining flexibility in media selection, reducing differential gloss and image relief, improving fuser reliability and lifespan, and enhancing overall gloss control.
In high-speed, high-quality electrophotographic printing applications, it may be desirable to get high gloss on the pictorial areas of an image but not on the text areas (i.e., differential gloss). As described in U.S. Pat. No. 5,234,783, issued to Ng, herein incorporated in its entirety by reference, this may be accomplished by selectively putting a transparent toner overcoat on the pictorial area. One example described in the Ng patent makes use of a lower viscosity toner so that there can be a higher gloss in the pictorial areas.
However, with high speed and high quality printing, there still can be disadvantages from the viewpoint of achieving higher gloss with heated roller fusing. For example, too much total toner coverage on the media may stress the fusing subsystem. Moreover, at the higher temperatures required to fuse a transparent toner overcoat along with the color toner lay-down, roller reliability as well as artifacts from the fuser roller oiler may become problematic. Additionally, there may also be problems relating to image relief differences between toner-covered areas versus adjacent areas without the transparent toner overcoat.
Other conventional systems to increase image gloss include an ultraviolet (UV) curable overcoat that may be applied over the total image or over, for example, only pictorial portions of the image. The UV curable overcoat may be applied by a conventional commercial printing coater or by ink jet printing, wherein a specific area may be coated selectively. However, with UV curable inks, even though image protection may be achieved over a wide variety of media, only certain types of coated media can benefit from the UV coating to lower differential gloss. In some cases, with uncoated matte media for example, differential glass can get worse with UV coating. Moreover, because most UV curable ink layers are a few microns thick, image relief may be quite visible on the dry electrophotographic prints.
As can be seen, there is a need for improved control of differential gloss on a wide variety of media substrates while minimizing image relief that may result from certain conventional differential gloss control methods.
As will be discussed in more detail below, a variety of technologies may be used to maintain flexibility in media selection, reduce differential gloss and relief, and improve fuser reliability and lifespan. These technologies include, for example, transparent toner overcoat, negative transparent toner masks, variable transparent toner screen mask, UV coater (off-line or ink jet), belt fusing, and transparent toner compensation for height relief. These technologies, when appropriately selected and applied, may be used to achieve overall appearance control for high quality and high-speed images.
The term “appearance” as used herein refers to those qualities well known in the art to those in the printing field. Such qualities include, for example, gloss, color density, differential gloss, and image relief.
The term “differential gloss” as used herein refers to the differences in image gloss among different portions of the same printed page.
The term “image relief” as used herein refers to differences in image surface heights along the same printed page.
The term “low differential gloss” as used herein refers to a difference in gloss value along a printed page of less than about 30 (in G60 units, for reference, please see Yee Ng, et al, “Standardization of Perceptual based Gloss and loss Uniformity for Printing Systems (INCITS W1.1)”, IS&T's 2003 PICS Conference Proceedings, pp. 88-93, 2003), in some instances less than about 20, and in other instances less than about 10.
The term “in-line” as used herein refers to a process occurring without user intervention, usually within the same apparatus as a previous process, while the term “off-line” as used herein refers to a process occurring after a break in the overall process, usually requiring the user to continue the process on a different apparatus or at a different location on the same apparatus.
In one aspect of the present invention, a method for controlling gloss and/or differential gloss of a printed image provides applying a color toner lay-down onto a media substrate to form a pre-fused image; applying a transparent toner over at least a portion of the pre-fused image to form a coated pre-fused image; fusing the coated pre-fused image to form a fused print; and finishing the fused print to increase a gloss value of the fused print.
In another aspect of the present invention, a method for controlling gloss and/or differential gloss of a printed image provides applying a color toner lay-down onto a media substrate to form a pre-fused image; applying a transparent toner over at least a portion of the pre-fused image as a negative mask to form a coated pre-fused image; selecting parameters for the negative mask to obtain a desired level of at least one of gloss, differential gloss and image relief; fusing the coated pre-fused image to form a fused print; and finishing the fused print to increase a gloss value of the fused print.
In yet another aspect of the present invention, a method for controlling gloss and/or differential gloss when creating a printed image on a printing device provides applying a color toner lay-down onto a media substrate to form a pre-fused image; fusing the coated pre-fused image to form a fused print; and finishing the fused print to increase a gloss value of the fused print.
In a further aspect of the present invention, a color image printing device provides a four-station color lay-down section for applying color toner to a media substrate to form a pre-fused image; a fifth station section for applying transparent toner to the pre-fused image; a fuser for fusing the pre-fused image into a fused image; and at least one of an in-line ink jet overcoat application device, an off-line ink jet overcoat application device, an in-line ultraviolet overcoat application device, and an off-line ultraviolet overcoat application device for increasing a gloss value of the fused image.
In still another aspect of the present invention, a computer readable media for controlling at least one of gloss and differential gloss of a printed image on a substrate provides a code segment for obtaining a desired level of gloss and differential gloss from a user; a code segment for reading an original image from which the printed image is to be made and calculating a color toner lay-down of the original image; a code segment for calculating an appropriate negative mask application of transparent toner based on at least one of the color toner lay-down of the original image, the desired level of gloss and differential gloss and the substrate.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and claims.
The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Broadly, the present invention provides for the controlling of differential gloss of a printed image while minimizing the negative effects of image relief. Conventional methods may use a transparent toner overcoat to achieve low differential gloss, high overall gloss, and image protection. However, often times conventional methods result in image relief that is unacceptable to the end customer. Further, the amount of transparent toner overcoat needed may stress the heated fuser roller, as an increase in the amount of transparent toner overcoat results in an increase in the amount of heat needed to fuse the toner (color lay-down plus transparent overcoat) onto the media substrate. By using a variety of technologies according to the present invention, such as transparent toner overcoat, negative transparent toner masks, variable transparent toner screen masks, UV coater (off-line or ink jet), belt fusing, and transparent toner compensation for height relief, one may achieve high overall image gloss and low differential gloss as well as protection for the fused image.
Referring to
Referring to
In the case of glossy coated media 200, after color toners were laid down (step 202) by the four color stations, the toned image can be fused (step 204 in sub-process A or step 210 in sub-process B) by regular heated roller fusing at high speed to get to a certain degree of gloss. Alternatively, the toned image may be fused with a smooth belt fuser to get to even higher gloss. One example of heated roller fusing may be found in U.S. Pat. No. 5,956,543. Examples of belt fusing may be found in U.S. Pat. Nos. 5,666,592; 5,890,032; and 5,887,234. Each of these patents is herein incorporated in their entirety by reference.
Due to different gloss levels of coated media, only a small number of media types are able to produce a relatively uniform gloss (i.e., small differential gloss, for example a differential gloss less than about 20) with varying amounts of toner coverage.
One method, as shown in sub-process A, to enhance overall image gloss while minimizing differential gloss may include using an in-line or off-line UV overcoat, as shown in step 206, that may be applied to the fused images (after step 204). Due to the similar level of adsorption of the UV overcoat into the coated media with respect to the toner-covered area, high gloss with low differential gloss can be achieved. High adjustable gloss (for example, a gloss value greater than 60) can be achieved with the proper selection of UV curable ink while maintaining low differential gloss. Image protection may also be achieved by this method. UV curable inks are known in the art for both image protection and imparting gloss. Examples of UV curable ink may be found in U.S. Pat. No. 5,371,058, issued to Wittig et al., herein incorporated in its entirety by reference.
However, because the UV overcoat can be quite thin (˜2 μm) compared with the toner coverage (for example, 280% maximum total four-toner coverage), high relief images can be seen. An appearance of larger color gamut may be achieved due to the increase in gloss. Therefore, lower toner coverage may be used to obtain a similar gamut compared with the original four-color toned images with this overcoat technique, thereby reducing relief images.
Another method, as shown in sub-process B, to accomplish a similar result as above (i.e., high gloss, low differential gloss, high relief image, and image protection) may include using an ink jet with UV ink, as shown in step 212, in the fifth station of the high speed printer. Because an ink jet application method is used, this method has the added advantage of being able to selectively gloss some of the image elements on every page. With the proper selection of UV curable ink, high gloss, some adjustable gloss (from varying the locations and amounts of ink jet UV curable ink lay-down), and low differential gloss can be obtained on coated glossy media. Of course, like the UV overcoat method of sub-process A previously discussed, the method of sub-process B also may produce high relief images on the toner-covered images. However, lower toner coverage may be possible to obtain a similar gamut compared with the original four-color toned image with the ink jet overcoat technique. Inks other than UV curable ink, such as thermal cross-linkable ink, can also be used for this purpose.
As shown in sub-process D, transparent toner overcoat may be used in the fifth station of the high-speed printer as shown in step 230. Regular heated roller fusing (step 232) may then be used to obtain a certain degree of uniform (i.e., lower differential gloss as compared to the four-color images) adjustable gloss in the printed image. Lower relief, as compared with the UV overcoat methods (sub-processes A and B) previously discussed, can be achieved due to the larger layer thickness (for example, >2 μm) of the toner overcoat. However, due to the thick transparent toner overcoat layer, in-line heated roller fusing may not have sufficient power to achieve a high gloss image. Gloss enhancements, after fusing the transparent toner overcoat, may be accomplished by either in-line ink jet UV system/curer or an off-line UV ink coater/curer, as shown in step 224. In this case, a wide range of paper may be used without the problem of differential surface adsorption (between toner laid down areas and non-toner laid down areas), since now the adsorption surface onto which the UV curable ink is applied is defined by the transparent toner overcoat surface rather than the paper surface (which may have varying surface adsorptions). Gloss enhancement may also be achieved in the above-described sub-process D by using a belt fuser on the previously roller-fused image (also shown in step 224). Alternatively, as shown in sub-process D′, overall gloss may be enhanced by using a high gloss special paper that has a softenable, polymer-based overcoat that the toner can be buried within. Fusing (roller-fusing with optional belt fusing) of this special paper, as shown in step 234, with the transparent toner overcoat layer may achieve a printed image with low differential gloss and low relief image.
Referring still to
If higher gloss is desired, then an in-line or off-line ink jet UV system/curer or regular UV coater/curer can be used, as shown in step 228, to bring up the overall gloss of the image while still retaining the low differential gloss and low relief images. Another method for increasing the overall image gloss may include using a post-press belt fuser, as shown in step 224 and as previously described. A further method for obtaining in-line gloss enhancement of low differential gloss and low relief images at high speed is to use an in-line ink jet UV overcoat system, as shown in step 228.
While
Referring to
Referring now to
Alternatively, the determination of the negative mask calculations required in step 220 of
Line 420 shows the desired negative mask calculation to achieve minimum color impact while matching substrate gloss for a glossy coated paper of intermediate level of gloss. In other words, if the user desires a print that would have a gloss value similar to the substrate gloss value, the amount of transparent toner negative mask to use on the substrate varies with the amount of four-color ink based on this curve.
Referring to
It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
Reference is made to the co-pending, commonly assigned, U.S. Provisional Patent Application Ser. No. 60/532,162 filed on Dec. 23, 2003, entitled: GLOSS AND DIFFERENTIAL GLOSS CONTROL MEHODOLOGY, the disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60532162 | Dec 2003 | US |
