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  Formation of retroreflective sheeting with controlled cap-yRelated Patent Categories: Stock Material Or Miscellaneous Articles, Structurally Defined Web Or Sheet (e.g., Overall Dimension, Etc.), Including Variation In Thickness, Composite Web Or SheetFormation of retroreflective sheeting with controlled cap-y description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070048501, Formation of retroreflective sheeting with controlled cap-y. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATION(S) [0001] This application is a division of U.S. application Ser. No. 10/815,366, filed Apr. 1, 2004. BACKGROUND OF THE INVENTION [0002] The present invention relates generally to reflective articles. The invention has particular application to retroreflective sheeting. [0003] Retroreflective materials are configured to receive light rays impinging upon a viewing surface and to alter the rays so that they are reflected back toward their sources. Retroreflective material is generally used to enhance the low-light visibility of an article to which the retroreflective material is attached. Such material is used in a variety of applications ranging from traffic signs to bicycle reflectors. By enhancing low-light visibility, retroreflective materials enhance safety, provide decoration, and increase conspicuity in general. [0004] Two known types of retroreflective material include microsphere-based sheeting and cube corner sheeting. Microsphere-based sheeting, sometimes referred to as "beaded" sheeting, employs a multitude of microspheres typically at least partially imbedded in a binder layer and having associated specular or diffuse reflecting materials (e.g., pigment particles, metal flakes, vapor coats) to retroreflect incident light. In general, however, such sheeting has a lower retroreflective efficiency than cube corner sheeting. [0005] Cube corner retroreflective sheeting comprises a body portion typically having a substantially planar viewing surface and a structured surface comprising a plurality of cube corner elements such as cube corner projections and cube corner cavities. Each cube corner element comprises three approximately mutually perpendicular optical faces that intersect at a cube apex or, where the cube apex is truncated, that otherwise converge at an uppermost portion. It is known to treat the structured surface with a specularly reflective coating to improve performance at high entrance angles. An example of this is vapor-coated retroreflective sheeting. [0006] Cube corner sheeting typically has a much higher retroreflectance than beaded sheeting, where retroreflectivity or brightness (these terms are used interchangeably herein) is expressed in units of candelas per lux per square meter. However, certain graphics applications require not only certain levels of retroreflectance but also particular levels of daytime "whiteness." The whiteness of an object is sometimes described in terms of the second of the tristimulus coordinates (X,Y,Z) for the object, and thus is referred to as "cap-Y." The cap-Y scale ranges from 0 for a perfectly black object to 100 for a perfectly white object. BRIEF SUMMARY OF THE INVENTION [0007] A retroreflective laminate sheeting has a viewing surface having a retroreflective layer which has a first cap-Y value of a viewing surface side thereof. A plurality of discrete pigmented indicia are disposed on the viewing surface side of the retroreflective layer. The pigmented indicia define a second cap-Y value of the viewing surface of the sheeting, the second cap-Y value being less than the first cap-Y value. One method of making a retroreflective sheeting includes forming a retroreflective layer on a web, the web moving in a web direction. The method includes applying a pigmented material proximate the retroreflective layer, the pigmented material preferably forming a plurality of parallel stripes oriented substantially in at least one of the web direction and a direction orthogonal to the web direction. BRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 is a perspective view of one embodiment of a retroreflective sheeting of the present invention. [0009] FIG. 2 is a perspective view of a second embodiment of a retroreflective sheeting of the present invention. [0010] FIG. 3 is a top plan view of one embodiment of a pigmented indicia distribution. [0011] FIG. 4a is a sectional elevation view of one embodiment of a retroreflective sheeting of the present invention. [0012] FIG. 4b is a sectional elevation view of a second embodiment of a retroreflective sheeting of the present invention. [0013] FIG. 5 is a top plan view of a portion of the retroreflective layer of FIG. 4. [0014] FIG. 6 is a sectional elevation view of a third embodiment of a retroreflective sheeting of the present invention. [0015] While the above-identified drawing figures set forth several embodiments of the invention, other embodiments are also contemplated. This disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this invention. The figures may not be drawn to scale. Like reference numerals have been used throughout the figures to denote like parts. DETAILED DESCRIPTION [0016] The present invention relates to a laminate and an article comprising a retroreflective layer having a retroreflective viewing surface and an opposing surface and a plurality of discrete pigmented indicia proximate the viewing surface. An overlay layer may optionally be disposed on the retroreflective layer. As used herein "retroreflective viewing surface" refers to the surface of the retroreflective layer (e.g. retroreflective sheeting), laminate or article that is viewed by an observer. The retroreflective viewing surface of the laminate or article may be the retroreflective sheeting, the overlay layer (if present), as well as either of these layers further comprising other transparent layers or coatings disposed between the retroreflective surface of the sheeting and the observer. [0017] Sheeting 10 shown in FIG. 1 is suitable for a number of applications including traffic and informational signs, clothing, vehicle markings, license plates, registration stickers, markers, flags, banners, tapes, decals, and any other applications where conspicuity or retroreflection is desired. While some applications benefit from sheeting with high levels of brightness and whiteness, in other applications, lower brightness or whiteness are desired. The present invention allows for the modification of existing retroreflective sheetings to meet the requirements of such latter applications without the need for developing new optical designs in the retroreflective layer. The present invention allows one to tailor the brightness and whiteness of a sheeting to the needed specification level by decreasing the brightness and/or whiteness of a particular retroreflective layer. The present invention allows for such customization in a much more cost effective and time efficient manner than developing new optical qualities for a retroreflective layer. Sheeting 10 includes a retroreflective layer 12 having a viewing surface side 14. Sheeting 10 also has a plurality of discrete pigmented indicia 16 disposed on the viewing surface side 14 of the retroreflective layer 12. Sheeting 10 can be formed from any retroreflective sheeting with the addition of pigmented indicia 16. The two most common types of retroreflective sheetings suitable for use are microsphere-based sheeting and cube corner-based sheeting. [0018] Sheeting 10 includes pigmented indicia 16 that are shown in the form of parallel markings in the illustrated embodiment. In an exemplary embodiment, indicia 16 are disposed over the entire viewing surface side 14 of sheeting 10. Indicia can include sets of dots, or other suitable shapes. In one example, indicia 16 are in the form of stripes having a uniform width ranging between about 0.1 mm (about 4 mils) and about 1.0 mm (about 39 mils), and more preferably between about 0.254 mm (about 10 mils) and about 0.508 mm (about 20 mils). In an exemplary embodiment, indicia 16 are in the form of stripes having a distribution density of from about 2 to about 10 stripes per centimeter (about 5 to about 25 stripes per linear inch). Additionally, it is preferred that pigmented indicia 16 cover a portion of the retroreflective viewing surface side 14 ranging from about 10% to about 25%, although other ranges are possible. [0019] In one method of producing retroreflective sheeting 10, sheeting 10 travels in web direction 18. In the illustrated embodiment, pigmented indicia 16 are oriented substantially in web direction 18. In the present application, "brightness" or "retroreflectivity" are measured by a coefficient of retroreflection. "Whiteness" is measured by a "cap-Y" scale. Pigmented indicia 16 can be disposed on sheeting 10 in numerous variations of orientations, indicia sizing, indicia density, indicia placement, and indicia pigmenting to achieve a desired brightness and whiteness of the viewing surface side 14 of sheeting 10. Pigmented indicia 16 effectively mask the retroreflectiveness and whiteness of retroreflective layer 12. Thus, if less brightness is desired in sheeting 10, pigmented indicia 16 can be configured to cover a greater area of the viewing surface side 14 of sheeting 10. This can be accomplished, for example, by increasing the size of each discrete pigmented element or by increasing the density of elements, or a combination of both. If decreased whiteness is desired, pigmented indicia 16 can be pigmented to a darker color to decrease the cap-Y value. Continue reading about Formation of retroreflective sheeting with controlled cap-y... Full patent description for Formation of retroreflective sheeting with controlled cap-y Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Formation of retroreflective sheeting with controlled cap-y patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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