This invention relates in general to controlling gloss in a printing system and more specifically to controlling gloss having a color hue. The printing system further includes a finishing system that is capable of printing with some specified level of gloss with a color hue in one or more areas of the final product.
Printing, such as electrophotography (EP), has become more and more capable of reproducing pictorial subject matter, especially in three or four colors in addition to a clear toner so that now users often desire to print textural material, graphics and/or pictorial subject matter. Users of office copiers and printers have an increasing demand for a combination of text and photo quality images in one print. Users are also demanding results similar to those achieved by professional print shops. Professional print shops produce documents such as brochures, certificates, pamphlets, and the like with spot gloss or spot varnish gloss with a color hue. This treatment can be a regional or image-wise coating of clear ink or toner.
In addition new printers have scanners associated with them to enhance functionality. These All-in-One printers have created the need for on-demand finishing functionality along with the development of a more energy efficient, quicker starting, lower cost, and more reliable fusing processes, that can deliver both quality text and proper image quality.
To meet the proper image quality in today's market, control of the image gloss, luster and other surface finishes has become more important. A user selectable gloss level and coverage in association with a specific color hue is also needed to satisfy end user demands. This is especially apparent when using a special need print, such as one including a watermark.
This invention is directed to a method of controlling gloss and differential gloss in a printing system and more specifically to controlling gloss and differential gloss having a color hue. The printing system further includes a finishing system that is capable of printing with some specified level of gloss with a color hue in one or more areas of a final product using a clear toner in combination with a very low color density toner screen pattern to produce glossy areas, for example watermarks (with a slight color hue), glossy highlighted patterns, or glossy images of any sort. For dramatic effects a large intentional differential gloss (or gloss contrast) can also be applied to specific areas of a page (e.g. glossy watermark with matte images and text).
Professional print shops produce documents, such as brochures, certificates, pamphlets, and the like with spot gloss or spot varnish. This treatment can be a regional or image-wise coating of clear ink or toner. Clear ink or toner can also be printed as a watermark such as a single or repeating phrase of logo that is barely visible on the document and appears as a an area or pattern of increased differential gloss relative to the unprinted area of the document as described in U.S. Pat. No. 7,228,006 entitled Method and system for detecting a geometrically transformed copy of an image and U.S. Pat. No. 6,888,647 entitled Proofing with watermark information created by a raster imaging processor. With the advent of a 5th station and clear toner in on-demand printing systems such as the Kodak NexPress 2500, it is now possible to add digitally addressable spot differential gloss to individual documents.
Multi function printers (MFP) are discussed in this description and include both scanning and printing functionality and equipment in one integrated unit. The integrated printer and scanning functionality can be physical, such that the printing systems the scanner and printer hardware are mechanically attached to each other. Alternatively the printing system can be a standalone printer that does not include a scanner.
The marking engine of the MFP system can be toner or ink jet based. One type of marking engine is an electrophotographic (EP) printer that uses EP toner. Toner is meant to include many types of marking materials including pigmented toner and dye based toners as well as other toner with and without a color. Typically, the image data file is processed by an image writing unit and printed onto receiver sheets that are picked by a paper handing unit, sometimes referred to as a paper picking unit, from a tray in the MFP all under control of a Central Control Unit [CCU]. In most MFP systems such printing is done with no regard for the gloss characteristics of the original or the receiver sheets resulting in copies of the original that do not reproduce the gloss level of the original.
In such systems featuring a scanner and printer, a major application is the copying of documents. This is done by first scanning the document using the scanning function. This may be a single page scan, usually done using a flat bed scanner or a multi-page scan, usually done using an automated document feeder (ADF). Then the scanned document is converted into digital data that can be used to produce a replica of the original document. Such copies are limited today to replicate the image content information. Other qualities of the original, such as the gloss of the original document, are not reproduced. This results in customer dissatisfaction because image gloss is an important component of the overall document's appearance.
This method for controlling gloss and/or differential gloss of a printed image includes determining pigmented toner type, transparent toner type and media type, also referred to as gloss input data to determine a final desired gloss 352 and/or a differential gloss of a fused image 354 before applying a small amount of pigmented toner to produce a low-color-density image from the four-color lay-down section 320 onto the media of the media type to form an image 356. The transparent toner is applied over at least a portion of the media substrate including the image 356 and fusing said image to form the fused image or print having the final desired gloss and the differential gloss of a fused image.
To control the gloss of a special mark such as a watermark the melt flow and solidification properties of the toner can be used as a control factor. The melt viscosity can be chosen based on the amount of contrast desired with the dominant marked images. For example: a gloss contrast of 30 units is desired between the dominant images and a watermark with a slight magenta hue: where the watermark has the higher gloss of the two. One can use a higher viscosity toner, around 16 kPoise for the colors, and a lower viscosity clear toner, around 10 kPoise for the watermark.
Viscoelastic properties that also influence the final gloss product are typically described by the property ratio tan δ. Tan δ is a ratio of the storage modulus (elastic modulus) and the loss modulus (viscous modulus),
In addition to using a specific set a viscosities to control the gloss contrast, toner area mass lay-down can be used. In general, as the toner area mass lay-down increases the gloss response increases. At low area mass lay-downs, less than 100% coverage, the scattered toner particles do not form a continuous film, after being sintered and glossed (or fused).
In conjunction with the toner properties and the toner area mass lay-down, the fusing process and operating set-points can produce a variety of gloss contrast levels. This allows the toner properties to be designed for the fusing process. Defining the fusing process and toner properties then set the possible operating window for gloss response with respect to each of the five toners: four primary colors and a clear (or transparent). This leaves the fuser operating set-points and the toner mass lay-down scheme to gain control over the gloss response for a certain desired (or specified) range with a specific fusing system and toner material set.
Referring back to
To achieve a high gloss a low viscosity toner with a toner area coverage greater than or equal to 100% can be used. This gloss can be placed locally, in a spot wise fashion, for an accentuated gloss contrast. This can be done with clear toner directly deposited onto the substrate, or it can be deposited over a stack of color toner. When deposited onto a stack of color toner, the clear toner may be deposited with an inverse mask that levels the height of the toner stack to the maximum level of the color toner, or it can be deposited in a uniform thickness (following the topography of the color toner stacks). Using the inverse mask can reduce the toner usage as long as the intended effects are achieved. The inverse mask may also be needed if fusing power is constrained. With higher toner stacks more energy is needed due to the increased thermal mass: therefore an inverse mask can maintain the smallest possible toner stack height for manipulating the gloss response.
When depositing clear toner particles in a uniformly thick layer over pigmented toner particles, varying the layer thickness (also known as stack height, which is directly proportional to area mass lay-down and toner % coverage) of the clear toner particles can modulate the gloss response. The gloss response shape will still behave in the manner shown in
In the case of a 163° F. initial temperature, shown in
According to one embodiment, an operator of a printer or a copier determines which portion of an image the operator wishes to have at a gloss area, for example, a watermark. The location of that gloss portion is input to the copier or printer, which creates an image of a gloss enhancing toner corresponding to that watermark. The electrostatographic printer uses toners to produce a background mark that is low in gloss, or nearly matches the paper gloss using a low area mass lay-down such that the toner particles are spaced apart enough to cause light to scatter (resulting in a low gloss).
If the spot gloss is to be produced using one of two clear toner options 604 where one of two clear toners are to be used for spot glossing 614 the options are to use a low viscosity toner 616 for a high spot gloss or a high viscosity toner 618 for a low spot gloss as discussed in more detail in the examples. For the high spot gloss option the % toner coverage laid down will need to be set so that it is greater then or equal to 100% before the job is run 620. For the low spot gloss option there are two toner coverage sub options shown. In the first when the % toner coverage laid down is estimated at less then 100% then there will be a very low toner spot gloss. In the second option 624 when the % toner coverage laid down will be greater then or equal to 30% then the job is run 620 will give a higher spot gloss then the first option.
For image enhancement, image relief elimination, and toner deposit mass control (or stack height control), a process using toner viscosity, fuser settings, and toner inverse mask techniques can be used. An illustration of this process can be seen in
If the enhanced image is to be produced using one of two clear toner options 704 where one of two clear toners will be used then first an image is selected 714 to be enhanced and it is determined whether the user wants to match the color toner gloss 716. If the color toner gloss is to match the color toner gloss 718 then the options are to use a low viscosity toner 720 for a high enhanced image gloss or a high viscosity toner 722 for a low enhanced image gloss before applying an inverse mask of the image 724, as discussed in detail above, before running the job 770.
If the enhanced image is to be produced using one of two clear toner options 704 and it is determined whether the user does not want to match the color toner gloss 726 then is must be determined if the gloss is to be lower 728 then the rest of the image or higher then the rest of the image 730. For a gloss option where the final gloss level is higher then the enhanced image option 728, a high viscosity toner 722 is applied that will result in a lower image gloss after applying a “hyper” mask of the image 732 before running the job 770.
If the enhanced image is to be produced using one of two clear toner options 704 but it is determined that the user does not want to match the color toner gloss 726 wants a wow factor where the gloss is to be higher 730 then the decision is made on the amount of gloss contrast desired 734. For a gloss option where the final gloss contrast level is to add more contrast to the enhanced image 736, a low viscosity toner 738 is applied that will result in a greater gloss contrast after applying a “hyper” mask of the image 740 before running the job 770.
In a second option when the user does not want to match the color toner gloss 726 and desires a lower gloss contrast 742 a combination of both the low viscosity toner and the high viscosity toner can be used in specified combinations 744 to yield the desired lower contrast that differs from the image gloss before applying an inverse mask 746 of the image 724 and applying some additional viscosity toner 748 before running the job 770. When the % toner coverage for this low viscosity toner to be laid down is determined it will need to be set so that it is greater then or equal to 100% before the job is run so that the result will give the desired enhanced image with a lower contrast gloss level.
A pigmented polyester toner being put-down, with a screen pattern, to produce a color density range correlating to approximately 1% to 20% toner coverage would produce a range of hue that would produce a background effect.
Polyester toners posses the properties to have a low melt viscosity, at fusing temperatures, for producing medium to high gloss color images of, text, graphics, and photographs. Low viscosity clear toner is the best way to achieve a medium to high gloss clear image with any level of background color hue.
A pigmented styrene-acrylic toner being put-down, with a screen pattern, to produce a color tone scale range correlating to approximately 1% to 20% toner coverage would produce a range of hue that would produce a background effect. Over this layer of pigmented toner a layer of clear polyester toner, equal to 100% toner coverage or higher that can produce the high gloss or a specific level of gloss, can be put-down. To get a specific level of gloss the clear toner flow viscosity, storage modulus, and loss modulus can be adjusted chemically, along with the amount of toner put down.
Styrene-acrylic toner has a higher melt flow viscosity than polyester toners, which produces a low level of gloss (good for text documents). This situation, where the pigmented toner produces low gloss images, allows for a larger contrast in gloss (for the targeted area) when using a polyester clear toner for raising the gloss in the target area. The areas of the image that did not receive clear toner will have a much lower gloss.
A pigmented polyester toner being put-down, with a screen pattern, to produce a color tone scale range correlating to approximately 1% to 20% toner coverage would produce a range of hue that would produce a background effect. Over this layer of pigmented toner a layer of clear styrene-acrylic toner, equal to 100% toner coverage or higher that can produce the high gloss or a specific level of gloss, can be put-down. To get a specific level of gloss the clear toner flow viscosity, storage modulus, and loss modulus can be adjusted chemically, along with the amount of toner put down.
Using a polyester toner for the primary colors, and styrene-acrylic toner for the background mark or image highlighting clear coat will produce an area of lower gloss, with respect to the remainder of the image. This would be considered a de-glossing process, where the gloss is lowered in a spot wise fashion with respect to the main image or images.
For the most dramatic effect, a large differential gloss can be intentionally created. The pigmented toner can produce a low gloss by possessing relatively high melt viscosity, from 30 kPoise to ˜130 kPoise. A clear toner, with a very low melt viscosity near 2 kPoise, to be specially located on the page can produce a high gloss of around 70 units measured at a 60 degree angle, whereas the pigmented toner would produce a gloss around 10 or 20 units measured at a 60 degree angle. This contrast of approximately 50 (60 degree gloss units) produces the dramatic effect. Under the clear toner, a low color density toner coverage can be used to get the slight color hue effect, while maintaining the large gloss contrast.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. This invention is inclusive of combinations of the embodiments described herein. References to a “particular embodiment” and the like refer to features that are present in at least one embodiment of the invention. Separate references to “am embodiment” or “particular embodiments” or the like do not necessarily refer to the same embodiment or embodiments; however, such embodiments are not mutually exclusive, unless so indicated or as are readily apparent to one of skill in the art. The use of singular and/or plural in referring to the “method” or “methods” and the like are not limiting