Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
1997-04-03
2003-01-21
Couso, Jose L. (Department: 2621)
Facsimile and static presentation processing
Static presentation processing
Attribute control
C358S502000, C358S515000, C358S518000, C358S520000, C345S603000, C345S604000, C347S043000, C347S100000, C347S105000, C347S171000
Reexamination Certificate
active
06509979
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to a method for printing a variety of colors on an absorbent substrate with a limited number of colorants. More specifically, this invention relates to a method to extend the perceived range of colors that can be printed on a substrate beyond those that are available using conventional printing methods. This method has particular utility when used with patterning systems that produce an image made up of a number of individual pixels to which individual quantities of colorants can be applied in accordance with a pre-defined patterning scheme.
To assist in the explanation of the operation and utility of this invention in its various embodiments, the following terms and definitions shall be used. As used herein, the term “color” shall encompass the concepts of hue, value or lightness, and chroma or saturation. The term “perceived color” shall mean the color perceived by a human observer at a distance at which individual pixels (as that term is defined herein) are not readily discernable. The term “pixel” shall be defined herein as the smallest area on the substrate onto which a controlled amount of colorant can be assigned with precision. This term is distinguishable from the term “pattern element.” As used herein, the term “pattern element” shall refer to a single pixel, but shall also refer to a group of two or more pixels that are used, as a group, to form a pattern. Pattern elements may be arranged on a substrate surface in a tiled configuration (i.e., in abutting relationship with adjacent elements, with no gaps and no overlaps between adjacent elements) to form a pattern or image. The term “pixel area” shall refer to a specific area on a substrate that comprises a pixel. The term “colorant” shall mean a liquid, readily flowable ink, dye, or other liquid coloring agent. This term is also intended to include a diluent that has no intrinsic color of its own. Accordingly, the term “color” as applied to a colorant used to practice this invention can include a “colorless” colorant that is used as an in situ diluent on the substrate. The term “available color” shall mean the perceived color resulting from the application of a single colorant to a set of pixels on an uncolored (white) absorbent substrate. The term is intended to distinguish these perceived colors, which can be obtained by using readily available colorants and no blending processes, from physically or optically blended colors. The term “physically blended color” refers to a color that is the result of a physical mixing of two or more different available colorants on the substrate, resulting in the in situ formation of a colorant with a color different from the constituent colorants. A perceived color that is produced using a diluent is a physically blended color. The term “optically blended color” refers to the perceived color that is generated by the juxtaposition or arrangement (including overlap) on the substrate of different colorants, none of which are individually distinguishable at a distance. The term “blended color” refers to either or both of these types of colors. The term “compound pixel” refers to at least two adjacent pixels, each of which are differently colored (either with an available color or with a color resulting from the physical mixing of two or more colorants applied to that pixel). The term “metapixel” refers to a group of two or more adjoining or contiguous pixels, in which at least one of the pixels has been oversaturated with colorant (i.e., the quantity of colorant within the substrate area defining that pixel—the pixel area—exceeds the absorptive capacity of the substrate within that pixel area) and at least one other pixel in the group has been undersaturated with a different colorant (i.e., the quantity of colorant within the substrate area defining that pixel area is less than the absorptive capacity of the substrate within that pixel area). As a result, colorant migration occurs within the metapixel from an oversaturated pixel area to one or more adjoining or contiguous pixel areas that were undersaturated. This pixel-to-pixel migration leads either to physical blending with, or displacement of, colorants in the adjacent pixel areas, and is a characteristic of the metapixels of this invention. Other terms shall be introduced and defined as required.
Imaging or printing systems that use the concept of pixels to place images on substrates are in common use in the printing and textile industries, and have been the subject of numerous research and development efforts. Among such systems are those capable of patterning substrates using discrete points of colorant. These points are familiar to many as the small “dots” that make up the illustrations found in newspapers and magazines printed using the gravure printing process. In that process, the printed images are comprised of many small dots of colorant, each assigned to a separately defined, specific area or pixel. The larger the colorant dot assigned to that pixel, the more effectively that pixel will influence the overall perceived color of the image containing that pixel. By varying the dot size assigned to the various pixels, it is possible to reproduce colors that are not directly represented by the available colorants. For example, a green area on a substrate can be effectively reproduced using only blue and yellow dots, or an orange area using only magenta and yellow dots. Use of this technique is not limited to gravure, but is also commonly employed in lithographic and other systems using half-tone imaging.
In these cases, the different colored dots are readily seen at very close range as separate blue, yellow, or magenta dots, but at a distance are perceived as the desired color, even though that color exists nowhere on the substrate. Alternatively, the dots may overlap and visually mix—perhaps a blue or magenta dot is seen “through” an overlapping yellow dot—so that some dots actually appear on the substrate at very close range as an optically blended color. It is important to note, however, that even in these cases where the dots overlap to form an optically blended color (similar to making colors using overlapping transparent films of different colors), the individual colorants applied to the substrate remain in discrete, intact units that can be visually identified. No physical mixing or blending takes place between the contiguous or overlapping dots, and no migration or displacement of colorant takes place between adjacent pixels.
The textile industry has been using pixel-based printing techniques for a number of years for the purpose of generating multi-colored images on various absorbent textile substrates. Examples of such printing techniques used by the assignee are described in U.S. Pat. Nos. 3,942,342; 3,969,779; 4,894,169; 5,128,876; 5,136,520; 5,142,481; 5,195,043; and 5,208,592, all of which are hereby incorporated by reference as if expressly set forth herein. These latter systems use a plurality of liquid colorant applicators that selectively apply pulsed streams of colorants onto a moving absorbent substrate. The applicators are arranged along one of several linear arrays that are positioned in parallel relationship across the path of the moving substrate. A different liquid colorant is supplied to each array. As the substrate passes under a given array, the liquid colorant associated with that array is delivered to the substrate from one or more applicators in the form of a metered stream that is directed to an individual pixel on the substrate. Colors that require blending (e.g., the green or orange discussed above, assuming those colors are not among the available colorants) are reproduced by placing the appropriate colors in adjacent pixels, so as to generate an optical blend of the proper color, or by placing separately two (or more) different colorants within the same pixel, so as to generate a physical blend within the same pixel.
Each applicator in a given array is equipped to deliver no colorant, or a variable amount of the colorant associat
Couso Jose L.
Desire Gregory
Fisher George M.
Milliken & Company
Moyer Terry T.
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