Patent Publication Number: US-9907168-B2

Title: Ribbed large-format imprinting method

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Reference is made to commonly-assigned U.S. patent application Ser. No. 14/475,854 (now U.S. Publication No. 2016/0062003), filed Sep. 3, 2014, entitled Filled Large-Format Imprinted Structure by Cok; to commonly-assigned U.S. patent application Ser. No. 14/475,869 (now U.S. Publication No. 2016/0062004), filed Sep. 3, 2014, entitled Filled Large-Format Imprinting Method by Cok; to commonly-assigned U.S. patent application Ser. No. 14/475,878 (now U.S. Publication No. 2016/0062176), filed Sep. 3, 2014, entitled Ribbed Large-Format Imprinted Structure by Cok; to commonly-assigned U.S. patent application Ser. No. 14/475,917 (now U.S. Publication No. 2016/0062006), filed Sep. 3, 2014, entitled Multi-Layer Large-Format imprinted Structure by Cok; to commonly-assigned U.S. patent application Ser. No. 14/475,934 (now U.S. Publication No. 2016/0062181), filed Sep. 3, 2014, entitled Multi-Layer Large-Format Imprinting Method by Cok; to commonly-assigned U.S. patent application Ser. No. 14/475,955 (now U.S. Pat. No. 9,545,000), filed Sep. 3, 2014, entitled Stacked Large-Format Imprinted Structure by Cok; to commonly-assigned U.S. patent application Ser. No. 14/475,974 (now U.S. Publication No. 2016/0062008), filed Sep. 3, 2014, entitled Stacked Large-Format Imprinting Method by Cok; to commonly-assigned U.S. patent application Ser. No. 13/784,866 (now U.S. Publication No. 2014/0251660), filed Mar. 5, 2013 entitled Variable Depth Micro-Channel Structure by Cok; and to commonly-assigned U.S. patent application Ser. No. 13/784,869 (now U.S. Pat. No. 8,895,429), filed Mar. 5, 2013 entitled Micro-Channel Structure with Variable Depths by Cok; the disclosures of which are incorporated herein. 
     FIELD OF THE INVENTION 
     The present invention relates to multi-layer imprinted structures having micro-cavities filled with cured materials. 
     BACKGROUND OF THE INVENTION 
     Color filter arrays are widely used with liquid crystal displays (LCDs) to provide color pixels. In such displays, each pixel is arranged to emit or reflect light through a color filter. The pixels are typically substantially rectangular with sides having lengths ranging from tens of microns to hundreds of microns, depending on the display size and resolution. For example, a pixel and corresponding color filter can have a size of 100 microns by 200 microns and a thickness of approximately a micron to tens of microns. A typical display can have a fill factor (the percentage of the display area covered by pixels and color filters) of 50% or even more. 
     The color filters are typically made using photolithographic processes in which surfaces are coated with a material (for example by evaporation, thermal transfer, or by a liquid coating containing dyes or pigments). The coated layer is then cured, if necessary, and photolithographically patterned, for example by coating a photoresist, exposing the resist to light such as ultra-violet (UV) light through a mask to develop a pattern in the resist corresponding to the mask, and etching the patterned resist and the underlying coated layer to form a color filter pattern corresponding to the mask. This process is expensive and time consuming because it is a subtractive process that is wasteful of etched materials, uses additional, expensive materials such as photoresists and masks, and requires expensive optical alignment equipment. 
     U.S. Pat. No. 6,497,981 describes a method of forming a color filter array. A substrate having a passivation layer thereon is provided. A negative color photoresist layer is formed over the passivation layer. A photolithographic exposure process is conducted using a light source with a wavelength less than or equal to 248 nm so that a pattern for forming a color filter array is imprinted on the negative color photoresist layer. In an alternative method, U.S. Patent Application Publication No. 20130038958 discloses a manufacturing method of a color filter array including providing a substrate; forming a light shielding layer on the substrate, the light shielding layer having a plurality of openings, the openings exposing a surface of the substrate, the light shielding layer having a height H; 
     performing an inkjet printing process to inject color filter ink into the openings of the light shielding layer; and performing a solidifying process to solidify the color filter ink to form a plurality of color filter patterns. In yet another approach, EP0365219 teaches a method of making an array of a repeating mosaic pattern of colorants carried on a support using (a) a plurality of donor materials each comprising respectively a sublimable dye of a different color, and (b) a receiver element comprising a support having thereon a dye-receiving layer, wherein each donor material is in turn brought into face-to-face contact with the receiver and heated patternwise by contact with a heated embossed surface to transfer the desired pattern of dye to the dye-receiving layer. 
     It is also known to form small-scale features in thin layers of curable materials such as cross-linkable polymers using an embossing or imprinting process. In such processes, a curable layer is coated over a substrate, the curable layer is imprinted with a stamp having desired relief features that project from the stamp surface into the curable layer, the curable layer is cured using heat or radiation depending on the attributes of the cross-linkable polymer, and the stamp is removed. Such processes can be fast, cover large areas, and are applicable to inexpensive roll-to-roll manufacturing processes. However, the area that is imprinted with a relief pattern is typically much smaller than the area that is not imprinted, since the imprinting process displaces material that must flow to another location in the imprinted layer. Thus, the imprinted area is relatively small compared to the total area of the cured material and the size of the features in the relief pattern is likewise relatively small, for example less than 20 microns in width. Thus, imprinted structures over a substrate typically have a small fill factor. 
     Methods for filling imprinted features in a layer are known, for example coating curable material over an imprinted substrate with relief features, removing excess curable material from the surface of the imprinted substrate but not the imprinted relief features, and curing the curable material in the relief features. However, as with the imprinting process itself, it is difficult to uniformly fill a large, imprinted area with a liquid that is subsequently cured. For example, the coffee-ring effect is widely known to compromise the uniformity of a dried coating because of capillary flow induced by differential evaporation rates over the extent of the coating. 
     Therefore, because of such imprinting and drying problems, it is difficult to form large fill-factor substrates, such as color filter substrates, using imprint-and-fill processes. 
     SUMMARY OF THE INVENTION 
     There is a need, therefore, for improved methods and materials for forming filled large-format imprinted structures including color filters with a large fill factor that provide improved uniformity and size, increases manufacturing speed, and requires less material and equipment. 
     In accordance with the present invention, a method of making a filled large-format imprinted structure comprises: 
     providing a substrate; 
     locating a curable layer over the substrate, imprinting the curable layer, and curing the curable layer to form a cured layer including a layer surface and one or more imprinted micro-cavities, wherein each micro-cavity has a micro-cavity depth and a micro-cavity width and one or more ribs extending from the bottom of the micro-cavity toward the top of the micro-cavity, each rib having a rib width that is less than one half of the micro-cavity width, a rib height that is less than the micro-cavity depth, and each rib separating the micro-cavity into portions, each portion having a portion width less than or equal to 20 microns; and 
     locating a curable material in each micro-cavity and curing the curable material to form cured material in each micro-cavity, thereby defining a filled large-format imprinted structure. 
     Structures and methods of the present invention provide color filters on a large fill-factor substrate and, more generally, provide filled large-format imprinted structures having improved uniformity and size using a process that decreases material requirement, increases manufacturing speed, and requires less material and equipment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of the present invention will become more apparent when taken in conjunction with the following description and drawings wherein identical reference numerals have been used to designate identical features that are common to the figures, and wherein: 
         FIG. 1  is a cross-sectional view of a multi-layer filled large-format imprinted structure in an embodiment of the present invention; 
         FIG. 2  is a plan view of the multi-layer filled large-format imprinted structure of  FIG. 1  in an embodiment of the present invention; 
         FIG. 3  is a cross-sectional view of a multi-layer filled large-format imprinted structure with separated micro-cavities in an embodiment of the present invention; 
         FIG. 4  is a cross-sectional view of an another multi-layer filled large-format imprinted structure with overlapping micro-cavities in an embodiment of the present invention; 
         FIG. 5  is a cross-sectional view of yet another multi-layer filled large-format imprinted structure with multiple micro-cavities per display pixel in an embodiment of the present invention; 
         FIGS. 6A and 6B  are enlarged cross-sectional views of a portion of a multi-layer filled large-format imprinted structure with multiple multi-layer micro-cavities per display pixel in an embodiment of the present invention; 
         FIG. 7  is a cross-sectional view of an alternative multi-layer filled large-format imprinted structure with ribs in an embodiment of the present invention; 
         FIG. 8  is a cross-sectional view of an alternative multi-layer filled large-format imprinted structure with variable width ribs in an embodiment of the present invention; 
         FIG. 9  is a cross-sectional view of an alternative multi-layer filled large-format imprinted structure with short ribs in an embodiment of the present invention; 
         FIG. 10  is a representation illustrating a wide micro-cavity useful in understanding the present invention; and 
         FIGS. 11-12  are flow diagrams illustrating various methods of the present invention. 
     
    
    
     The Figures are not necessarily to scale, since the range of dimensions in the drawings is too great to permit depiction to scale. 
     DETAILED DESCRIPTION OF THE INVENTION 
     According to various embodiments and methods of the present invention, filled large-format imprinted structures such as color filters having improved uniformity and size are provided by using structures and processes that decrease material requirements, increase manufacturing speed, and require less equipment. As is described more fully below, imprinting processes form relief features or structures such as micro-cavities in a curable layer. Once the curable layer is cured, the micro-cavities are filled with a curable material and dried to form, for example, color filters. Multiple stacked cured layers, arrangements of micro-cavities in the stacked cured layers, and structures formed in the micro-cavities in the cured layers mitigate problems found in structures and methods of the prior art. 
     Additive imprinting processes are known to form small features such as micro-cavities in cured layers at a relatively high rate compatible with inexpensive roll-to-roll processes with less waste than other processes such as photo-lithographic processes. Multiple cured layers reduce the relative quantity of imprinted material in a given layer and structures within the imprinted micro-cavities improve the distribution of curable material, such as color filter material, within the micro-cavities. 
     Referring to  FIG. 10 , it has been discovered through experimentation that materials dried within a large area, for example a wide micro-cavity having a width greater than 20 microns does not dry evenly within the micro-cavity. Furthermore, when a liquid material coated over the surface and micro-cavities of the cured layer is removed from the surface of the cured layer, for example by wiping, to leave the liquid material only in the micro-cavities, if the micro-cavity is too wide the liquid material is also removed from the micro-cavity by the wiping device. Even repeated coatings of the liquid material will not solve this wiping problem, since the coated liquid material is repeatedly wiped from the wide micro-cavities. 
     As is readily observed in  FIG. 10 , the dried material is thinner in the center than at the edges of the micro-cavity. If the dried material is a color filter that is uniformly illuminated, the result would be a non-uniform color transmitted through and across the color filter, since a thinner color filter does not saturate light as a thicker color filter does, thereby providing a display with less saturated colors and pixels that are not uniform. 
     According to embodiments of the present invention, a filled large-format structure  5  includes a layer of cured material having imprinted micro-cavities that are filled with a cured material, for example forming color filters. Referring to  FIG. 1 , the filled large-format imprinted structure  5  includes a substrate  8  and a first cured layer  10  located over the substrate  8 . First micro-cavities  12  are imprinted in the first cured layer  10  and a first cured material  14  of a first color is located in the first micro-cavities  12 . A second cured layer  20  is located over the first cured layer  10 , the first micro-cavities  12 , and the first cured material  14 . Second micro-cavities  22  are imprinted in the second cured layer  20  and a second cured material  24  of a second color is located in the second micro-cavities  22 . A third cured layer  30  is located over the second cured layer  20 , the second micro-cavities  22 , and the second cured material  24 . Third micro-cavities  32  are imprinted in the third cured layer  30  and a third cured material  34  of a third color is located in the third micro-cavities  32 . The first, second, and third colors can all be different colors, for example red, green, or blue, corresponding to the primary colors of a display. 
     In an embodiment, the substrate  8  is a transparent substrate and the first, second, and third cured layers  10 ,  20 ,  30  are transparent layers. In another embodiment, the substrate  8  is a component of a display  6  such as an LCD or OLED display, for example the cover or substrate of the display  6  through which light from an array of pixels is emitted, reflected, or transmitted. The display  6  includes an array of pixels such as a first pixel  16 , a second pixel  26 , and a third pixel  36 , each of which independently controls emitted, transmitted, or reflected light and corresponds, for example, to colored pixels such as red, green, and blue pixels. As is well known in the art, some LCD and OLED displays use a white-light backlight whose light is patterned according to pixels controlled by a display controller (not shown) and colored by color filters. The display  6  in the present invention can emit white light that is colored by color filters provided by the large-format imprinted structures  5  of the present invention. The large-format imprinted structures  5  are filled with dyes or pigments to color light from the display pixels transmitted through the filled large-format imprinted structures  5 . According to the present invention, the large-format imprinted structures  5  filled with dyes or pigments are referred to as color filters, but the present invention is not limited to color filter applications only. 
     According to another embodiment of the present invention, the large-format imprinted structure  5  further includes the display  6  having at least the first, second, and third pixels  16 ,  26 ,  36  located beneath the first cured layer  10 , the first pixel  16  located at least partially beneath the first micro-cavity  12 , the second pixel  26  located at least partially beneath the second micro-cavity  22 , and the third pixel  36  located at least partially beneath the third micro-cavity  32 . 
     As used herein, the first, second, and third micro-cavities  12 ,  22 ,  32  are structures imprinted in the first, second, and third cured layers  10 ,  20 ,  30 , respectively, and can also be referred to as micro-channels or micro-structures. The term micro-cavity is used in other arts to refer to an optical cavity with reflective surfaces that cause constructive optical interference at particular optical frequencies corresponding to the depth of the micro-cavity. However, in the present invention, reflective surfaces are not necessarily present in the micro-cavities and the term micro-cavity simply refers to a small imprinted cavity, opening, indentation, or channel in a cured layer and does not imply any optical interference or constructive resonant effects. The micro-cavities can have any useful shape, regular or irregular, for example rectangular, polygonal, or with curved edges. The micro-cavities can be immediately adjacent in a layer or layers, for example having a common edge in a direction orthogonal to a surface of the substrate  8 . The micro-cavities can form long, thin structures that are termed micro-channels. Alternatively, each micro-cavity is separated from other micro-cavities by a gap in one or two dimensions. 
     Referring to the plan view of  FIG. 2 , the first, second, and third micro-cavities  12 ,  22 ,  32  form an array of micro-channels that extend a length L across the substrate  8 . Each micro-channel can correspond to a row (or column) of display pixels and the first cured material  14 , the second cured material  24 , and the third cured material  34  form color filters in the micro-channels associated with the rows (or columns) of display pixels. The cross section of  FIG. 1  is taken along the cross section line A of  FIG. 2 . Although it is the cured materials that filter light, the cured materials are located in the micro-cavities and it is understood that the micro-cavities with cured materials located therein filter light and are also referred to as color filters. Therefore, references to a micro-cavity can also refer to the corresponding cured material located in the micro-cavity and vice versa. 
     Referring to both  FIGS. 1 and 2 , an embodiment of the filled large-format imprinted structure  5  of the present invention includes the first, second, and third micro-cavities  12 ,  22 ,  32  having widths of W 1 , W 2 , and W 3  formed in the first, second, and third cured layers  10 ,  20 ,  30  having depths of D 1 , D 2 , and D 3 , respectively. The first micro-cavities  12  and the corresponding cured materials  14  located in the first cured layer  10  are separated by a first gap  51  and have a depth D 4 . The second micro-cavities  22  and the corresponding second cured materials  24  located in the second cured layer  20  are separated by a second gap S 2  and have a depth D 5 . The third micro-cavities  32  and the corresponding cured materials  34  located in the third cured layer  30  are separated by a third gap S 3  and have a depth D 6 . 
     As shown in  FIG. 1 , the first cured material  14  in the first cured layer  10  is aligned with the first pixel  16 , the second cured material  24  in the second cured layer  20  is aligned with the second pixel  26 , and the third cured material  34  in the third cured layer  30  is aligned with the third pixel  36 . In this illustration, there is no separation gap between the first, second, and third pixels  16 ,  26 ,  36  or the first, second, and third cured materials  14 ,  24 ,  34  within the group G. Thus, an embodiment of the present invention includes the first micro-cavity  12  adjacent to the second micro-cavity  22  adjacent to the third micro-cavity  32  forming the first group G, a different first micro-cavity  12  adjacent to a different second micro-cavity  22  adjacent to a different third micro-cavity  32  forming a second group G in a direction parallel to a surface of the substrate  8 . 
     In an embodiment, the groups G correspond to full-color pixels and each individual first, second, or third pixel  16 ,  26 ,  36  is a single-color pixel or sub-pixel. Thus, the first pixel  16  and corresponding first cured material  14  aligned with the second pixel  26  and corresponding second cured material  24 , and the third pixel  36  and corresponding third cured material  34  forms a full-color pixel and is separated from a neighboring full-color pixel by the separation gap S, at least in a direction orthogonal to the extent of the imprinted micro-channels and parallel to a surface of the substrate  8 . Such an arrangement can enable efficient filling of the micro-cavities with liquid curable materials. Although the illustration of  FIG. 2  shows imprinted micro-channels extending a length L across the substrate  8 , in other embodiments, imprinted elements forming micro-cavities are separately formed in an array so that no pixel or micro-cavity is in contact with a neighboring pixel or micro-cavity and each micro-cavity is separated from each other micro-cavity. 
     As shown, the first micro-cavity  12  has a first depth D 4  that is less than the first cured layer  10  thickness D 1 , the second micro-cavity  22  has a depth D 5  that is less than the second cured layer  20  depth D 2 , or the third micro-cavity  32  has a depth D 6  that is less than the third cured layer  30  thickness D 3 . The depth is taken in a direction orthogonal to a surface of the substrate  8 . For clarity, as used herein the thickness of a layer or material is also referred to as the depth of the layer or material and refers to the thickness of the layer or material in a direction perpendicular to a surface of the substrate  8 . Generally, micro-cavities are referred to as having a depth and layers and materials are referred to as having a thickness. By ensuring that the thickness of a layer is greater than the depth of a micro-cavity imprinted in the layer, the amount of material that is displaced by imprinting relative to the total amount of material in the layer is reduced. At the same time, it is useful to employ relatively thin layers, for example less than 20 microns, less than 10 microns, less than five microns, less than two microns, or even less than one micron to reduce the total amount of material in the imprinted cured layers. However, those skilled in the art will appreciate that the depth of the micro-cavities will depend, at least in part, by the desired thickness of the first, second, and third cured materials,  14 ,  24 ,  34  necessary to filter the light from the first, second, and third pixels  16 ,  26 ,  36  to a desired color saturation. This thickness will depend on the nature of the cured materials (e.g. dye or pigment load and material type) and the spectrum of light from the corresponding pixel. 
     In other embodiments, the first cured layer  10  has a thickness D 1  that is different from the thickness D 2  of the second cured layer  20 , the first cured layer  10  has a thickness D 1  that is different from the thickness D 3  of the third cured layer  30 , or the second cured layer  20  has a thickness D 2  that is different from the thickness D 3  of the third cured layer  30 . Correspondingly, the first micro-cavity  12  has a depth D 4  that is different from the depth D 5  of the second micro-cavity  22 , the first micro-cavity  12  has a depth D 4  that is different from the depth D 6  of the third micro-cavity  32 , or the second micro-cavity  22  has a depth D 5  that is different from the depth D 6  of the third micro-cavity  32 . Similarly, the first cured material  14  has a thickness D 4  that is different from the thickness D 5  of the second cured material  24 , the first cured material  14  has a thickness D 4  that is different from the thickness D 6  of the third cured material  34 , or the second cured material  24  has a thickness D 5  that is different from the thickness D 6  of the third cured material  34 . Since different color filters require different materials providing different amounts of saturated light from a white-light source with a variable-intensity spectrum, it is useful to employ different thicknesses of materials in differently colored filters. 
     In another useful embodiment illustrated in  FIG. 1 , the first micro-cavity  12  has a spatial area that is different from the spatial area of the second micro-cavity  22 , the first micro-cavity  12  has a spatial area that is different from the spatial area of the third micro-cavity  32 , or the second micro-cavity  22  has a spatial area that is different from the spatial area of the third micro-cavity  32 . In this way, each pixel or corresponding color filter can have a different area. As shown in  FIG. 1  (but not in the lower resolution plan view of  FIG. 2 ), the width W 1  of the first micro-cavity  12  is greater than the width W 2  of the second micro-cavity  22  and less than the width W 3  of the third micro-cavity  32 . The area of a micro-cavity is directly related to the width of the micro-cavity. A micro-cavity can have a different size than another micro-cavity in any spatial dimension, including width, length, or, as noted above, depth. Such differently sized arrangements are useful, for example to provide different amounts of colored light from each pixel, and are used to improve a display with respect to the response of the human visual system. 
     As noted above and illustrated in  FIGS. 1 and 2 , the first, second, and third cured materials  14 ,  24 , and  34  are aligned in groups G and a separation gap S separates the groups G. First, second, and third cured materials  14 ,  24 ,  34  within a group G are located in separate layers but are aligned with edges in a common line in a plan view of the substrate  8 . In an alternative embodiment, as illustrated in  FIG. 3 , the first, second and third cured materials  14 ,  24 ,  34  in different cured layers  10 ,  20 ,  30  are separated by the gap S in a direction parallel to a surface of the substrate  8 . Referring to  FIG. 3 , according to an embodiment of present invention, the filled large-format imprinted structure  5  forming color filters includes the substrate  8  and the first cured layer  10  located over the substrate  8 . First micro-cavities  12  are imprinted in the first cured layer  10  and the first cured material  14  of a first color is located in the first micro-cavities  12 . The second cured layer  20  is located over the first cured layer  10 , first micro-cavities  12 , and first cured material  14 . Second micro-cavities  22  are imprinted in the second cured layer  20  and a second cured material  24  of a second color is located in the second micro-cavities  22 . The third cured layer  30  is located over the second cured layer  20 , second micro-cavities  22 , and second cured material  24 . Third micro-cavities  32  are imprinted in the third cured layer  30  and the third cured material  34  of a third color is located in the third micro-cavities  32 . The first, second, and third colors can all be different colors, for example red, green, and blue, corresponding to the primary colors of a display. 
     As shown in  FIG. 3  (and  FIG. 2 ), the first micro-cavities  12  are spaced apart by first gaps  51 , the second micro-cavities  22  are spaced apart by second gaps S 2 , and the third micro-cavities  32  are spaced apart by third gaps S 3  ( FIG. 2 ) in a direction parallel to a substrate surface. In one embodiment, the first, second, and third gaps S 1 , S 2 , S 3  are the same (as shown); in another embodiment the first, second, and third gaps S 1 , S 2 , S 3  are different. As shown in  FIG. 3 , the first, second, and third micro-cavities  12 ,  22 ,  32  and the first, second, and third cured materials  14 ,  24 ,  34  in a group G are separated by a gap P in a direction parallel to a surface of the substrate  8 . The groups G of first, second, and third cured materials  14  are separated by the gap S. The gaps P are useful for routing control and power signals to the display pixels. In a useful embodiment, S is larger than P so that groups G of full-color pixels are separated by a gap S greater than the separation gap P separating single-color pixels within a group forming a full-color pixel. This assists the human visual system to blend the separate, differently colored first, second, and third pixels  16 ,  26 ,  36  into one full-color pixel (corresponding to a group G) while providing room to route power and control signals in the display. 
     The arrangement of  FIG. 3  leaves gaps P between the pixels that could decrease the perceived saturation of pixels since white light from a display backlight can travel between the first, second, and third cured materials  14 ,  24 ,  34  without traveling through them. In an embodiment, this is mitigated by providing another, fourth cured layer  40  with fourth micro-cavities  42  having cured material  44  located at least partly above the first gaps S 1  between first micro-cavities  12 , the second gaps S 2  between the second micro-cavities  22 , the third gaps S 3  between the third micro-cavities, above the gaps P between the first and second micro-cavities  12 ,  22 , above the gaps P between the second and third micro-cavities  22 ,  32 , or above the gaps P between the first and third micro-cavities  12 ,  32 . In an embodiment, the fourth cured material  44  is black (for example including carbon black), so that the fourth cured layer  40  serves as a black matrix for the display  6 . 
     Although the fourth cured layer  40  is shown on a side of the first, second, and third cured layers  10 ,  20 ,  30  opposite the display  6 , it can be located between any of the first, second, or third layers  10 ,  20 ,  30  or, in a useful embodiment, between the first, second, and third layers  10 ,  20 ,  30  and the display  6  (not shown). Likewise, the order of the first, second, or third layers  10 ,  20 ,  30  relative to the substrate  8  are interchangeable. Thus, the words above or below are relative and can be interchanged depending on the relative orientation and location of the substrate  8 , the first layer  10 , the second layer  20 , the third layer  30 , and the fourth layer  40 . Moreover, when a micro-cavity or cured material is located above or below a pixel or other micro-cavity, a line directed orthogonally to a surface of the substrate  8  passes through the micro-cavity or cured material and the pixel or other micro-cavity. Thus, light emitted or reflected by the pixel orthogonally to the substrate will pass through the micro-cavity or cured material. Similarly, when a layer is located above or below another layer, a line directed orthogonally to a surface of the substrate  8  passes through the two layers. 
     In the arrangement of  FIG. 3 , the first micro-cavities  12  are located beneath the second gaps S 2  or the third gaps S 3 , or both. Likewise, the second micro-cavities  22  are located above the first gaps  51  or beneath the third gaps S 3 , or both. Similarly, the third micro-cavities  32  are located above the first gaps  51  or above the second gaps S 2 . In a useful embodiment, the fourth micro-cavities  42  are located above or below the gaps P between the first, second, or third micro-cavities  12 ,  22 ,  32  in a group G, or above or below the gaps S between the groups G of the first, second, or third micro-cavities  12 ,  22 ,  32 . Such an arrangement permits the fourth cured material  44  to absorb light emitted from a display that does not pass through any of the first, second, or third cured materials  14 ,  24 ,  34 . 
     Referring to  FIG. 4  in another embodiment of the present invention, the first, second, or third cured materials  14 ,  24 ,  34  overlap in a direction orthogonal to a surface of the substrate  8  to provide light absorption. As shown in  FIG. 4 , the first micro-cavities  12  are located at least partially beneath the second micro-cavities  24  and at least partially beneath the second gaps S 2  or are located at least partially beneath the third micro-cavities  32  and at least partially beneath the third gaps S 3  to form an overlap  80 . Likewise, the second micro-cavities  22  are located at least partially beneath the third micro-cavities  32  and at least partially beneath the third gaps S 3  to form the overlap  80  and the third micro-cavities  32  are located at least partially above the first micro-cavities  12  and at least partially above the first gaps  51  to form the overlap  80 . In a further embodiment of the present invention, the filled large-format imprinted structure  5  includes the display  6  having a plurality of pixels (e.g. first, second, and third pixels  16 ,  26 ,  36 ) separated by pixel gaps P located beneath the first cured layer  10 . The fourth micro-cavity  42  is located at least partly above the pixel gaps P. The overlapped portions of the first, second and third cured materials  14 ,  24 ,  34  effectively form a black filter when the first, second, and third cured materials  14 ,  24 ,  34  have different primary colors. For example, red light passed through the first cured materials  14  is absorbed by green second cured material  24  or by blue third cured material  34 . Similarly, green light passed through green second cured material  24  is absorbed by blue third cured material  34 . 
     According to embodiments of the present invention, the first micro-cavity  12  is less than or equal to 20 microns wide, the second micro-cavity  22  is less than or equal to 20 microns wide, or the third micro-cavity  32  is less than or equal to 20 microns wide. 
     The present invention is especially useful when relatively large areas are imprinted or filled. In particular as noted above with respect to  FIG. 10 , experimentation has shown that large imprinted areas, for example of the size corresponding to a pixel are difficult to fill and cure uniformly. Hence, according to another embodiment of the present invention and as illustrated in  FIG. 5 , a filled large-format imprinted structure  5  useful for color filters includes the substrate  8 . The first cured layer  10  is located over the substrate  8 . One or more first micro-cavities  12  are imprinted in the first cured layer  10 , each first micro-cavity  12  having a first micro-cavity width W 1  less than or equal to 20 microns. The second cured layer  20  is located over the first layer  10  and the one or more first micro-cavities  12 . One or more second micro-cavities  22  is imprinted in the second cured layer  20 , each of the second micro-cavities  22  having a second micro-cavity width W 2  less than or equal to 20 microns. A common cured material (e.g. first cured material  14 ) is located in the first micro-cavity  12  and in the second micro-cavity  22 , thereby defining the filled large-format imprinted structure  5 . In an embodiment, the cured material is a color filter. The first and second micro-cavities  12 ,  22 , and first cured materials  14  make up a first area  18  that corresponds to the area of the first pixel  16 . 
     In a further embodiment of the present invention, the third cured layer  30  is located over the second cured layer  20  and the one or more second micro-cavities  22 . One or more third micro-cavities  32  is imprinted in the third cured layer  30 , each third micro-cavity  32  having a third micro-cavity width W 3  less than or equal to 20 microns. A fourth cured layer  40  is located over the third layer  30  and the one or more third micro-cavities  32 . One or more fourth micro-cavities  42  is imprinted in the fourth cured layer  40 , each fourth micro-cavity  42  having a fourth micro-cavity width W 4  less than or equal to 20 microns. A common cured material (e.g. second cured material  24 ) is located in the third micro-cavity  32  and in the fourth micro-cavity  42 . The third and fourth micro-cavities  32 ,  42 , and second cured materials  24  make up a second area  28  that corresponds to the area of the second pixel  26 . 
     A fifth cured layer  50  is located over the fourth layer  40  and the one or more fourth micro-cavities  42 . One or more fifth micro-cavities  52  is imprinted in the fifth cured layer  50 , each fifth micro-cavity  52  having a fifth micro-cavity width W 5  less than or equal to 20 microns. A sixth cured layer  60  is located over the fifth cured layer  50  and the one or more fifth micro-cavities  52 . One or more sixth micro-cavities  62  is imprinted in the sixth cured layer  60 , each sixth micro-cavity  62  having a sixth micro-cavity width W 6  less than or equal to 20 microns. A common cured material (e.g. third cured material  34 ) is located in the fifth micro-cavity  52  and in the sixth micro-cavity  62 . The fifth and sixth micro-cavities  52 ,  62 , and third cured materials  34  make up a third area  38  that corresponds to the area of the third pixel  36 . 
     In yet another embodiment, a seventh cured layer  70  is located over the sixth cured layer  60  and the one or more sixth micro-cavities  62 . One or more seventh micro-cavities  72  are imprinted in the seventh cured layer  70  and include cured material (e.g. fourth cured material  44 ) therein. In an embodiment, the width of the seventh micro-cavities is less than 20 microns. Although not shown, in an embodiment an eighth layer with imprinted micro-cavities is also formed over the seventh cured layer  70  and includes the same cured material as in the seventh micro-cavities  72 . 
     As in other embodiments of the present invention, the substrate  8  can be the display  6  or element of the display  6  such as the display cover or display substrate. The display  6  can have first, second, and third pixels  16 ,  26 ,  36  arranged in groups G to form full-color pixels. The first cured material  14  in the first and second micro-cavities  12 ,  22  are associated with the first pixel  16  of the display  6  and can form a single effective color filter for the first pixel  16 . Likewise, the second cured material  24  in the third and fourth micro-cavities  32 ,  42  are associated with the pixel  26  of the display  6  and can form a single effective color filter for the pixel  26 . Similarly, the third cured material  34  in the fifth and sixth micro-cavities  52 ,  62  are associated with the pixel  36  of the display  6  and can form a single effective color filter for the pixel  26 . In a useful embodiment, the cured material in the seventh layer  70  (and eighth layer, if present) is a black fourth cured material  44  and serves as a black matrix for the display  6 . 
     Thus, in an embodiment of the present invention, the filled large-format imprinted structure  5  further includes the display  6  located beneath the first cured layer  10 . The display  6  has a single pixel (e.g. first pixel  16 ) located at least partially beneath the first and at least partially beneath the second micro-cavities  12 ,  22 . Thus, the cured material  14  in the first and second micro-cavities  12 ,  22  serve as a single effective color filter for the first pixel  16 . 
     Although  FIG. 5  illustrates two layers having the same cured material in separate micro-cavities in each of the two layers to form a single effective color filter, in other embodiments more than two layers are used and the cured material in each micro-cavity of the layers has a common material forming a single color filter. By locating the same cured material in two (or more) layers, a larger effective color filter in multiple layers is formed for a single pixel. Thus, effective color filters larger than the size of a single imprinted and filled micro-cavity are formed in a simple, repetitive coat, imprint, and fill process and associated in the display  6  with pixels that are larger than structures readily formed by imprinting processes. 
     Referring to  FIG. 6A  in an alternative embodiment of the filled large-format imprinted structure  5  the first cured layer  10  is formed on the substrate  8  or the display  6  having the single-color first pixel  16 . The first cured layer  10  includes two or more first micro-cavities  12  located above the single-color first pixel  16 . The second cured layer  20  is formed on the first cured layer  10  and includes two or more second micro-cavities  22  located above the single pixel  16 . The first and second micro-cavities  12 ,  22  in the two layers form the first area  18 . The cured material  14  is located in the first and second micro-cavities  12 ,  22  forming a single effective color filter having a size equal to four times the size of one of the first or second micro-cavities  12 ,  22 . Each cured layer can include more than two separated micro-cavities, for example having a width of 20 microns or less, to form a color filter of an arbitrary size. Thus, an advantage of the embodiment of  FIG. 6A  (and  FIG. 6B  described below) is that a larger effective area is filled without requiring additional cured layers or causing difficulties with imprinting relatively large areas in a layer. 
     As shown in  FIG. 6A , the two or more first micro-cavities  12  located in the first cured layer  10  are separated by a gap equal to or less than the width of the second micro-cavities  22 . Additionally, the two or more second micro-cavities  22  located in the second cured layer  20  are separated by a gap equal to or less than the width of the first micro-cavities  12 . 
     Referring to  FIG. 6B , since most displays  6  are viewed at a variety of angles, it is important that light Z emitted or reflected from the first pixel  16  at non-orthogonal angles pass through the color filters. To ensure such light filtering, it is useful for the common cured materials in adjacent layers to overlap. For example, referring to the filled large-format imprinted structure  5  of  FIG. 6B  the first and second micro-cavities  12 ,  22  on the substrate  8  or display  6  and the first cured material  14  in the first and second cured layers  10 ,  20  overlap so that light Z can pass through cured material in both cured layers. Although the amount of first cured material  14  through which light Z from the first pixel  16  passes will vary with the angle of emission or reflection, if the first cured material  14  in the first cured layer  10  overlaps with the first cured material  14  in the second cured layer  20 , it is more likely that light Z will pass through at least a portion of the first cured material  14 . 
     In this case, the two or more first micro-cavities  12  located in the first cured layer  10  are separated by the gap P less than the width W 2  of the second micro-cavities. Similarly, the two or more second micro-cavities  22  located in the second cured layer  10  are separated by the gap P less than the width W 1  of the first micro-cavities  12 . 
     The cured layers  10 ,  20 ,  30 ,  40 ,  50 ,  60 ,  70  are illustrated in a particular order in  FIG. 5 , but can be provided in any order above or below the substrate  8 . 
     According to embodiments of the present invention, the first and second cured layers  10  and  20  of the embodiments of  FIGS. 5, 6A, and 6B  serve as the single cured layer  10  of the embodiments of  FIGS. 1, 3 and 4 . Similarly, the third and fourth cured layers  30  and  40  of the embodiments of  FIG. 5  serves as the single cured layer  20  of the embodiments of  FIGS. 1, 3 and 4  and the fifth and sixth cured layers  50  and  60  of the embodiment of  FIG. 5  serves as the single cured layer  30  of the embodiments of  FIGS. 1, 3 and 4 . Thus, the structures discussed with reference to  FIGS. 1-4  above are also applicable to the structures of  FIGS. 5 and 6  so that in embodiments, the substrate  8  and the cured layers  10 ,  20 ,  30 ,  40 ,  50 ,  60 ,  70  are transparent or the cured layers  10 ,  20 ,  30 ,  40 ,  50 ,  60 ,  70  can have different thicknesses. Likewise, the micro-cavities  12 ,  22 ,  32 ,  42 ,  52 ,  62 ,  72  and the cured materials  14 ,  24 ,  34 ,  44  can have different thicknesses or spatial areas, are separated by gaps so that the cured materials  14 ,  24 ,  34 ,  44  are aligned and do not overlap, are separated by a gap and do not overlap, or overlap. Likewise in an embodiment, the first cured materials  14  are located between the second cured materials  24  or the second and third cured materials  24 ,  34  in a direction parallel to a surface of the substrate  8 . Similarly, in an embodiment, the second cured materials  24  are located between the first cured materials  14  or the first and third cured materials  14 ,  34  in a direction parallel to a surface of the substrate  8  and the third cured materials  34  are located between the first cured materials  14  or the first and second cured materials  14 ,  24  in a direction parallel to a surface of the substrate  8 . Additionally, the fourth cured material  44  is located between any or all of the first, second, or third cured materials  14 ,  24 ,  34  in a direction parallel to a surface of the substrate  8 . Alternatively, the first cured materials can overlap with the second or third cured materials  24 ,  34  and the second cured materials  24  can overlap with the third cured materials  34  in a direction orthogonal to a surface of the substrate  8 . 
     The embodiments of the present invention shown in  FIGS. 1-6B  illustrate large imprinted structures composed of multiple layers of smaller adjacent or overlapping structures. In another embodiment of the present invention, multiple structures are provided in a common layer and correspond to a single pixel. Referring to  FIGS. 7 and 8 , a filled large-format imprinted structure  5  includes the first cured layer  10  including a first cured layer surface  11  having one or more first areas  18 . The first cured layer  10  is formed on the substrate  8 , for example a cover or substrate of the display  6 . A plurality of first micro-cavities  12  are imprinted in each first area  18 , each of the first micro-cavities  12  having a micro-cavity width W 1  less than or equal to 20 microns. A rib  90  separates each first micro-cavity  12  from an adjacent first micro-cavity  12  by a rib width R that is less than the first micro-cavity width W 1 , the rib  90  extending from a bottom of the first micro-cavity  12  to the first cured layer surface  11 . The common first cured material  14  is in each first micro-cavity  12 , thereby defining the filled large-format imprinted structure  5 . In an embodiment, the common first cured material  14  is a color filter. 
     In a further embodiment of the present invention, the large-format imprinted structure  5  includes the second cured layer  20  having a second cured layer surface  21  having one or more second areas  28 . The second cured layer  20  is formed on the first cured layer  10 , the first micro-cavities  12 , and the first cured materials  14 . A plurality of second micro-cavities  22  are imprinted in each second area  28 , each of the second micro-cavities  22  having a micro-cavity width W 2  less than or equal to 20 microns. The rib  90  separates each second micro-cavity  22  from an adjacent second micro-cavity  22  by a rib width R that is less than the second micro-cavity width W 2 , the rib  90  extending from a bottom of the second micro-cavity  22  to the second cured layer surface  21 . In an embodiment, the plurality of second micro-cavities  22  and rib  90  are located at least partly between the first micro-cavities  12  in a direction parallel to a substrate surface. A common second cured material  24  is in each second micro-cavity  22 . In an embodiment, the common second cured material  24  is a color filter. 
     In another embodiment of the present invention, the large-format imprinted structure  5  includes the third cured layer  30  having a third cured layer surface  31  having one or more third areas  38 . The third cured layer  30  is formed on the second cured layer  20 , the second micro-cavities  22 , and the second cured materials  24 . A plurality of third micro-cavities  32  are imprinted in each third area  38 , each of the third micro-cavities  32  having a micro-cavity width W 3  less than or equal to 20 microns. The rib  90  separates each third micro-cavity  32  from an adjacent third micro-cavity  32  by a rib width R that is less than the third micro-cavity width W 3 , the rib  90  extending from a bottom of the third micro-cavity  32  to the third cured layer surface  31 . In an embodiment, the plurality of third micro-cavities  32  and rib  90  are located at least partly between the first micro-cavities  12  or second micro-cavities  22  in a direction parallel to a substrate surface. A common third cured material  34  is in each third micro-cavity  32 . In an embodiment, the common third cured material  34  is a color filter. 
     In yet another embodiment of the present invention, the large-format imprinted structure  5  includes the fourth cured layer  40  having a fourth cured layer surface  41  having one or more fourth areas  48 . The fourth cured layer  40  is formed on the third cured layer  30 , the third micro-cavities  32 , and the third cured materials  34 . A plurality of fourth micro-cavities  42  are imprinted in each fourth area  48 , each of the fourth micro-cavities  42  having a micro-cavity width W 4  less than or equal to 20 microns. The rib  90  separates each fourth micro-cavity  42  from an adjacent fourth micro-cavity  42  by a rib width R that is less than the fourth micro-cavity width W 4 , the rib  90  extending from a bottom of the fourth micro-cavity  42  to the fourth cured layer surface  41 . The common fourth cured material  44  is in each fourth micro-cavity  42 . 
     In other embodiments, the ribs  90  have a width that is less than or equal to 20 microns, for example 10 microns, 5 microns, two microns, or one micron. Alternatively, the ribs  90  have a rib width R that is less than or equal to one half, one quarter, one tenth, or one twentieth of the width (W 1 , W 2 , W 3 , W 4 ) of the micro-cavities ( 12 ,  22 ,  32 ,  42 ) that the ribs  90  separate. For example, in the first cured layer  10 , the rib  90  has a width R that is one tenth of the width W 1  of the first micro-channel  12 . The micro-cavities  12 ,  22 ,  32 ,  42  in each cured layer  10 ,  20 ,  30 ,  40  respectively can have a depth that is less than the cured layer thickness or less than 20 microns. Referring specifically to  FIG. 8  in a further embodiment, the rib widths R of ribs  90  separating the different micro-channels are different. As shown in  FIG. 8 , the rib width R separating the fourth micro-channels  42  and the fourth cured materials  44  in the fourth cured layer  40  is greater than the rib widths R separating the first, second, and third micro-cavities  12 ,  22 ,  32  and the first, second, and third cured materials  14 ,  24 ,  34  in the first, second, and third cured layer  10 ,  20 ,  30 . 
     In an embodiment, the common fourth cured material  44  is a color filter or a black material forming a black matrix and the first, second, and third cured materials are red, green, and blue cured materials. Although the cured layers  10 ,  20 ,  30 ,  40  are illustrated in a particular order in  FIG. 7 , they can be provided in any order above or below the substrate  8 . 
     Referring further to  FIG. 8  and according to another embodiment of the present invention, fourth cured material  44  in fourth micro-cavities  42  in fourth cured layer  40  is located above or below the ribs  90  in a direction perpendicular to a surface of the substrate  8 . As noted above, in an embodiment the fourth cured material  40  is black and forms a black matrix layer. As shown in  FIG. 8 , at least some of the fourth cured material  44  acts as a light absorber for light that could otherwise be emitted through or reflected by the ribs  90 . 
     In another embodiment, not separately illustrated, the fourth cured layer  40  includes only fourth micro-cavities  42  aligned with the ribs  90  in the first, second, or third cured layers  10 ,  20 ,  30 . In such an arrangement, one or more fourth micro-cavities  42  are imprinted in the fourth cured layer  40 , each of the second micro-cavities  42  having a micro-cavity width and a micro-cavity height both less than or equal to 20 microns. The fourth cured material  44 , for example a black material, is located in each fourth micro-cavity  42 . The fourth micro-cavities  42  are located above or below the ribs  90  in a direction perpendicular to a surface of the substrate  8 . Although labeled as the fourth cured layer  40  in  FIG. 8 , the same structure is useful in combination with a single cured layer, such as first cured layer  10 , in which case the fourth cured layer  40 , the fourth micro-cavities  42  and the fourth cured material  44  become a second cured layer  20  with second micro-cavities  22  and second cured materials  24 . As noted above, the layers can be in any order and the numbering of the layers is arbitrary. 
     In an embodiment, the first, second, and third cured materials  14 ,  24 ,  34  have different colors, for example red, green, and blue and the fourth cured material  44  is black. In various embodiments, any of these colors could be provided in the cured materials of any of the cured layers. 
     In another embodiment, one of the plurality of micro-cavities imprinted in an area is a different size or a different shape than another of the plurality of micro-cavities imprinted in the area. 
     As shown in  FIGS. 7 and 8 , the large-format imprinted structure  5  further includes the display  6  beneath the first cured layer  10 , the display  6  having the first pixel  16  located at least partially beneath the first area  18 . In further embodiments, the large-format imprinted structure  5  further includes second and third pixels  26 ,  36  located at least partially beneath each of the second and third areas  28 ,  38 , respectively. Each plurality of first, second, or the third micro-cavities  12 ,  22 ,  32  and ribs  90  is located in the first, second, or third areas  18 ,  28 ,  38 , respectively and associated with the corresponding first, second, or third pixels  16 ,  26 ,  36 . The first, second, and third cured materials  14 ,  24 ,  34  are color filters for the corresponding first, second, or third pixels  16 ,  26 ,  36  and has one of the colors red, green, and blue, and the fourth cured material  44  is black. The pixel can have a shape and the plurality of micro-cavities imprinted in an area together has a shape that corresponds to the shape of a pixel. A corresponding shape is a similar shape or a shape that substantially or completely covers the pixel. 
     The embodiments of  FIGS. 7 and 8  provide an advantage of requiring fewer cured layers. 
       FIGS. 7 and 8  illustrate a micro-cavity structure that has a rib separating micro-cavities in an area that extends from the bottom of the micro-cavities to the surface of the cured layer in which the micro-cavities are formed. In an alternative embodiment illustrated in  FIG. 9 , first, second, third, and fourth cured layers  10 ,  20 ,  30 ,  40  are formed over the substrate  8  such as the display  6  or display component such as a cover or substrate. First, second, third, and fourth micro-cavities  12 ,  22 ,  32 ,  42  are formed in the first, second, third, and fourth cured layers  10 ,  20 ,  30 ,  40 , respectively. The rib  90  is formed within each micro-cavity that extends from the bottom of the micro-cavity to a location lower than the surface of the cured layer in which the micro-cavities are formed. In such an embodiment, a filled large-format imprinted structure  5  includes the first cured layer  10  including the first cured layer surface  11 . One or more first micro-cavities  12  are imprinted in the first cured layer  10 , each first micro-cavity  12  having a first micro-cavity width W 1  and a first micro-cavity depth D 1 . One or more ribs  90  are imprinted in each first micro-cavity  12  and extend from the bottom of the first micro-cavity  12  toward the top of the first micro-cavity  12 , each rib  90  having a rib width R that is less than one half of the first micro-cavity width W 1 , a rib height H that is less than the micro-cavity depth D 1 , and each rib  90  separating the first micro-cavity  12  into portions O, each portion O having a portion width OW less than or equal to 20 microns. The first cured material  14  is located in each portion O of the first micro-cavity  12  and extends over the top of the rib  90 , thereby defining a filled large-format imprinted structure  5 . 
     In various embodiments of the present invention (see also  FIG. 1 ), the first, second, third, or fourth cured material  14 ,  24 ,  34 ,  44  is a color filter or is black, the first, second, third, or fourth micro-cavity depth D 1 , D 2 , D 3 , D 4  is less than the cured layer thickness S 1 , S 2 , S 3 , S 4 , respectively, or the first, second, third, or fourth cured layer  10 ,  20 ,  30 ,  40  is substantially transparent or has different thicknesses. In an embodiment, one of the first, second, third, or fourth micro-cavities  12 ,  22 ,  32 ,  42  has a different spatial area than another of the first, second, third, or fourth micro-cavities  12 ,  22 ,  32 ,  42 . In another embodiment, at least one portion O of the first, second, third, or fourth micro-cavity  12 ,  22 ,  32 ,  42  has a different size, a different shape, or a different area than another portion O of the first, second, third, or fourth micro-cavity  12 ,  22 ,  32 ,  42 . The first, second, third, or fourth cured material  14 ,  24 ,  34 ,  44  can have different colors. 
     In a further embodiment, the large-format imprinted structure  5  further includes the display  6  beneath the first cured layer  10  and the display  6  has the first pixel  16  located at least partially beneath the first micro-cavity. The first pixel  16  can have a shape and the first micro-cavity  12  can have a shape that corresponds to the shape of the first pixel  16 . Further, the display  6  can have a second and third pixels  26 ,  36  located at least partially beneath the second and third micro-cavities  22 ,  32 , respectively. Each plurality of first, second, or the third micro-cavities  12 ,  22 ,  32  and ribs  90  is located in the first, second, or third areas  18 ,  28 ,  38 , respectively and associated with the corresponding first, second, or third pixels  16 ,  26 ,  36 . In an embodiment, the first, second, and third cured materials  14 ,  24 ,  34  are color filters having one of the colors red, green, and blue, and the fourth cured material  44  is black. Although not shown in  FIG. 9 , the light-absorbing fourth cured material  44  of  FIG. 8  located above the ribs  90  is usable above the ribs  90  in the embodiment of  FIG. 9 . 
     The embodiments illustrated in  FIGS. 7, 8, and 9  have an advantage in that the ribs serve to prevent a mechanical device that removes material from the surface of the cured layers from also removing material from the micro-cavities, or at least serve to reduce the amount of material removed from the micro-cavities. The full-height ribs  90  of  FIGS. 7 and 8  are more effective at reducing the impact of mechanical cured surface wiping but can permit light to pass through the ribs  90 . In contrast, the shorter ribs  90  of  FIG. 9  are less effective at reducing the impact of mechanical cured surface wiping but filter, at least somewhat, light passing through the ribs  90 . 
     In an embodiment, the cured layers  10 ,  20 ,  30 ,  40  of  FIGS. 7, 8 , and  9  correspond to the cured layers  10 ,  20 ,  30 ,  40  of  FIG. 1 , respectively. Thus, the structures discussed with reference to  FIGS. 1-4  above are also applicable to the structures of  FIGS. 7, 8, and 9  so that in embodiments, the substrate  8  and cured layers  10 ,  20 ,  30 ,  40  of  FIGS. 7, 8, and 9  are transparent or the cured layers  10 ,  20 ,  30 ,  40  of  FIGS. 7, 8, and 9  can have different thicknesses. Likewise, the micro-cavities  12 ,  22 ,  32 ,  42  of  FIGS. 7, 8, and 9  and the cured materials  14 ,  24 ,  34 ,  44  of  FIGS. 7, 8, and 9  can have different thicknesses or spatial areas, are separated by gaps so that the cured materials  14 ,  24 ,  34 ,  44  are aligned and do not overlap, are separated by a gap and do not overlap, or overlap. Likewise in an embodiment, the first cured materials  14  are located between the second cured materials  24  or second and third cured materials  24 ,  34  in a direction parallel to a surface of the substrate  8 . Similarly, in an embodiment, the second cured materials  24  are located between the first cured materials  14  or first and third cured materials  14 ,  34  in a direction parallel to a surface of the substrate  8  and the third cured materials  34  are located between the first cured materials  14  or first and second cured materials  14 ,  24  in a direction parallel to a surface of the substrate  8 . Additionally, the fourth cured material  44  is located between any or all of the first, second, or third cured materials  14 ,  24 ,  34  in a direction parallel to a surface of the substrate  8 . Alternatively, the first cured materials  14  can overlap with the second or third cured materials  24 ,  34  and the second cured materials  24  can overlap with the third cured materials  34  in a direction orthogonal to a surface of the substrate  8 . 
     In operation for each of the embodiments, a display controller (not shown) controls the first, second, and third pixels  16 ,  26 ,  36  of the display  6  to emit, reflect, or transmit light Z through the corresponding first, second, and third cured materials  14 ,  24 ,  34  to filter the light Z and provide colored-light pixels for the display  6  as illustrated in  FIG. 1 . Overlapping micro-cavities such as those illustrated in  FIGS. 4 and 6B , more effectively filter light Z emitted, transmitted, or reflected at a non-orthogonal angle. The first, second, and third cured materials  14 ,  24 ,  34  can serve as color filters to provide full-color pixels for display  6  in which the display  6  is a white-light emitter, for example with an LCD backlight or a white-light emitter in an OLED display. Black materials located between pixels ( FIG. 3 ), between groups of pixels ( FIG. 3 ), or above ribs separating micro-pixels in an area ( FIG. 8 ) absorb incident ambient light or emitted, transmitted, or reflected display white light so as to improve the contrast of the display  6 . 
     All of the embodiments illustrated in the figures and discussed above can be constructed using similar or the same methods and processes. Referring first to  FIG. 11 , in step  100  the substrate  8  is provided. In various embodiments, the substrate  8  is transparent, flexible, or rigid and has a substantially planar surface. Glass or plastic can both be used. In an embodiment, the substrate  8  is a component of the display  6 , such as a display substrate or display cover of an LCD or OLED display. Sequential steps  201  through  204  are similar steps for forming sequential cured layers on the substrate  8 . In step  201 , the first cured layer  10  is formed over the substrate  8 , patterned to make the first micro-cavities  12 , and the first micro-cavities  12  filled with the first cured material  14 . In step  202 , the second cured layer  20  is formed over the first cured layer  10 , the first micro-cavities  12 , and the first cured materials  14 . The second cured layer  20  is patterned to make the second micro-cavities  22 , and the second micro-cavities  22  are filled with the second cured material  24 . In step  203 , the third cured layer  30  is formed over the second cured layer  20 , the second micro-cavities  22 , and the second cured materials  24 . The third cured layer  30  is patterned to make the third micro-cavities  32 , and the third micro-cavities  32  are filled with the third cured material  34 . In step  204 , the fourth cured layer  40  is formed over the third cured layer  30 , the third micro-cavities  32 , and the third cured materials  34 . The fourth cured layer  40  is patterned to make the fourth micro-cavities  42 , and the fourth micro-cavities  42  are filled with the fourth cured material  44 . Although the steps  201 - 204  are illustrated in an order, these four steps can be performed in any desired order and still form effective structures of the present invention. The steps  201 - 204  can be repeated as many times as necessary to provide the number of imprinted layers desired, for example seven times as illustrated in the structure of  FIG. 5 . 
     Each of the steps  201 - 204  can be performed using the steps  205 - 235  of step  200  illustrated in  FIG. 12 . Referring to  FIG. 12 , in step  205  a curable layer is coated over a surface. The curable layer can be, for example, a cross-linkable resin known in the art. Alternatively, a layer of curable material is laminated over the surface. Coating methods can include slot coating, curtain coating, or spin coating and laminating methods are known in the art. The curable layer is mechanically imprinted (stamped or embossed) in step  210  with a stamp having a surface with relief features corresponding to the desired micro-cavities and any ribs at the desired locations. Mechanical imprinting methods and stamp construction methods are known in the art. The curable layer is cured in step  220 , for example with heat or ultra-violet radiation, to form a cured layer (e.g. first, second, third, or fourth cured layers  10 ,  20 ,  30 ,  40 ) having micro-cavities (e.g. first, second, third, or fourth micro-cavities  12 ,  22 ,  32 ,  42 ). In an embodiment, the curable layer is cured by exposure through the substrate  8 . In another embodiment, the curable layer is cured by exposure from a side of the curable layer opposite the substrate. Since the cured materials can include light filtering or absorbing materials, curing the curable layers and materials from a side of the curable layer opposite the substrate is advantageous in some embodiments. Such curing methods are known. The imprinting stamp is mechanically removed in step  220 . 
     In step  225 , the cured layer surface and the micro-cavities are coated with a curable material, for example a cross-linkable material in liquid form with dyes or pigments using coating methods known in the art, for example spray or curtain coating. Excess curable material is removed from the surface of the cured layer (but not the micro-cavities) in step  230 , for example by wiping the surface, using methods known in the art. In the prior art, this wiping step is problematic since it can remove curable material that is desirably located in the micro-cavities. The limitation of micro-cavity width to 20 microns or less and the use of ribs within or separating micro-cavities mitigate this wiping problem in various embodiments of the present invention. Once the excess curable material is removed, the remaining curable material in the micro-cavities is cured in step  235 , for example by drying, heating, or exposure to radiation, as is known in the art. As noted above with reference to  FIG. 10 , curable materials that have a proportion of liquid and that are located in relatively large micro-cavities such as those with a dimension greater than 20 microns, tend to dry non-uniformly, in particular the thickness of the dried, cured material tends to be thinner at the center of the micro-cavity than at the edges. The limitation of micro-cavity width to 20 microns or less and the use of ribs within or separating micro-cavities also mitigate this curing problem in various embodiments of the present invention. Although drying non-uniformity problems can also be addressed by other methods known in the art (by controlling the material composition and drying conditions, for example), the present invention provides an alternative simpler, easier, and lower-cost method for mitigating the problem. Alternatively, the curable material is deposited in the micro-cavities, for example using ink jet deposition devices. 
     In an embodiment, the steps  225  to  235  are repeated for each cured layer until the micro-cavities in the layer are satisfactorily filled with cured material. 
     The use of multiple layers having micro-cavities filled with cured material or ribs within or separating micro-cavities in a layer enable filled large-format imprinted structures  5  that are larger than those made by other methods known in the art. In turn, the filled large-format micro-cavity structures  5  enable color filters or black matrix structures that are useful with displays having pixels with a spatial dimension greater than 20 microns. 
     The different steps  201 - 204  of  FIG. 11  can be performed using the same equipment in the same way, reducing manufacturing costs. The cured layers (e.g. first, second, third, or fourth cured layers  10 ,  20 ,  30 ,  40 ) can have the same materials and can be coated in the same way (step  205  in  FIG. 12 ). The micro-cavities (e.g. first, second, third, or fourth micro-cavities  12 ,  22 ,  32 ,  42 ) are located in different locations in the corresponding cured layers and, if ribs  90  are employed have a different structure. These different locations and structures can be imprinted using different stamps (in step  210  of  FIG. 12 ), each stamp having a relief structure corresponding to the micro-cavity structure of the particular curable layer imprinted. In some cases, if the micro-cavities themselves are identical in different cured layers but have different locations, the same stamp can be used but is registered and aligned to a different location over the substrate  8 . In any case, the same imprinting and registration mechanism can be used. The stamps can be registered to align the micro-cavities with the location of display pixels, to align with the micro-cavities in other cured layers, or to provide desired overlap between micro-cavities in different cured layers. The curing and stamp removal steps (steps  215  and  220  in  FIG. 12 ) are identical for each curable layer, as is the coating step (step  225 ). However, in useful embodiments the curable material used for each layer is different, for example a common curable material (such as a cross-linkable resin) with different additives, such as colored pigments to form different color filters when cured. The remaining removal step (step  230 ) and curing step (stamp  235 ) can be the same. 
     Thus, the present invention provides a way to construct a variety of multi-layer micro-cavity structures using common steps and with differences for each layer only in the imprinting stamp and in the selection of curable materials for filling the imprinted micro-cavities in each layer. For example, in the embodiment of  FIG. 3 , the imprinting stamp for the first cured layer  10  has relief features corresponding to the first micro-cavities  12  aligned with the first pixels  16 , the imprinting stamp for the second cured layer  20  has relief features corresponding to the second micro-cavities  22  aligned with the second pixels  26 , the imprinting stamp for the third cured layer  30  has relief features corresponding to the third micro-cavities  32  aligned with the third pixels  36 , and the imprinting stamp for the fourth cured layer  40  has relief features corresponding to the gaps between the micro-cavities in the other layers.  FIGS. 5, 6A, and 6B  illustrate a structure that requires multiple cured layers for one pixel and an imprinting stamp that imprints micro-cavities at different locations in each cured layer. The same imprinting stamp with a different registration over the substrate  8  can be used for each cured layer or a commonly registered different imprinting stamp used for each cured layer with relief features in locations corresponding to the different locations of the desired micro-cavities. In this case, each of the steps  201 - 204  are repeated twice sequentially with the different imprinting stamps with a common cured material located in the micro-cavities of each cured layer associated with the same pixel. In step  240 , the display  6  with pixels (e.g. first, second, and third pixels  16 ,  26 ,  36 ) is aligned with the first, second, and third micro-cavities  12 ,  22 ,  32  and first, second, third, and fourth cured materials  14 ,  24 ,  34 ,  44 . 
     In an alternative method, the micro-cavities are formed in alignment with the first, second, and third pixels  16 ,  26 ,  36  of the display  6 . In the embodiment of  FIG. 5 , a pixel (e.g. first, second, or third pixels  16 ,  26 ,  36 ) is aligned with the micro-cavities (e.g. first, second, or third micro-cavities  12 ,  22 ,  32 ) and cured material (e.g. first, second, or third cured materials  14 ,  24 ,  34 ) in an area (e.g. first, second, or third areas  18 ,  28 ,  38 ) so that light from the pixel passes through any of the micro-cavities and cured material in the area. By aligned is meant that light Z ( FIG. 1 ) emitted, reflected, or transmitted by the first, second, or third pixels  16 ,  26 ,  36  passes through the first, second, or third micro-cavities  12 ,  22 ,  32  and first, second, or third, cured materials  14 ,  24 ,  34 , respectively. In an embodiment, the first, second, and third micro-cavities  12 ,  22 ,  32  and first, second, and third, cured materials  14 ,  24 ,  34  are located above or below at least a portion of the first, second, and third pixels  16 ,  26 ,  36  in a direction perpendicular to a surface of the substrate  8 . 
     The structures of  FIGS. 7, 8, and 9  can be formed using the same process as that used for  FIG. 3  but with different imprinting stamps. In the cases illustrated in  FIGS. 7, 8, and 9  the imprinting stamps contain relief features that form the ribs  90  when applied to a curable layer. 
     In a further embodiment of the present invention, the first cured material  14  is cross-linked to the first cured layer  10 , the second cured material  24  is cross-linked to the second cured layer  20 , the third cured material  34  is cross-linked to the third cured layer  30 , or the fourth cured material  44  is cross-linked to the fourth cured layer  40 . Alternatively, the first cured layer  10  is cross-linked to the second cured layer  20 , the second cured layer  20  is cross-linked to the third cured layer  30 , or the fourth cured layer  40  is cross-linked to the third cured layer  40 . More generally, any cured layer is cross linked to a cured layer with which it is in contact or the cured material in the cured layer. 
     In such embodiments, both the curable materials and the curable layers include cross-linkable materials that cross link when cured. For example, both the first curable material  14  and the first curable layer  10  can include a common curable resin, for example cured with ultra-violet radiation or heat, that cross links when cured. Such cross-linking between the first cured material  14  and the first cured layer  10  improves the strength and the scratch resistance of the imprinted structure. This is accomplished by only partially curing the curable layer and then more completely curing the curable layer at the same time as the curable material is cured. Similarly, two curable layers that are in contact can be cross-linked by only partially curing the first located curable layer or curable material and then more completely curing the curable layer or curable material when the second curable layer is cured. More generally, the curable layers or curable materials are only cured sufficiently at each step to enable the subsequent processing step (for example coating the second curable material over the first cured layer surface or coating the second curable layer over the first cured material). Each subsequent cure step then cures the layers present more completely until, at the end, the entire structure is completely cured. Such partial curing steps at each stage of the process also reduce processing time and intensity of radiation or heat in the curing steps. Thus, according to an embodiment of the present invention, the curing step is a partial curing step and layers or materials are repeatedly partially cured. By cross-linking the various curable layers and materials, the filled large-format imprinted structure  5  is strengthened. 
     According to various embodiments of the present invention, the substrate  8  is any material having a substrate surface on which the first curable layer  10  can be formed. For example, glass and plastic are suitable materials known in the art from which the substrates  8  can be made into sheets of material having substantially parallel opposed sides, one of which is the substrate surface. In various embodiments, substrate  8  is rigid, flexible, or transparent. The substrate  8  can have a wide variety of thicknesses, for example 10 microns, 50 microns, 100 microns, 1 mm, or more. 
     Methods for the preparation, coating, and curing of light-absorbing curable materials including pigments, dyes, or carbon black are known, as are ultra-violet and heat curable cross-linkable resins. In another embodiment, the curable material includes a colored dye or a colored pigment other than black. 
     In various embodiments, imprinted micro-cavities are holes, indentations, pits, grooves, trenches, or channels formed in the cured layers and extending from a surface of the cured layer (for example first, second, third, or fourth cured layer surface  11 ,  21 ,  31 ,  41 ) toward the substrate  8 . Micro-cavities can have a cross-sectional width W, for example less than or equal to 20 microns, 10 microns, 5 microns, 4 microns, 3 microns, 2 microns, 1 micron, or 0.5 microns. In an embodiment, the cross-sectional depth D of an imprinted micro-cavity is less than or equal to the width of the micro-cavity, less than or equal to twice the width of the micro-cavity, less than or equal to four times the width of the micro-cavity, or less than or equal to ten times the width of the micro-cavity. The micro-cavities can have a rectangular cross-section, as shown. Other cross-sectional shapes, for example trapezoids, are known and are included in the present invention. 
     Material compositions useful in the curable layer or the curable material can be provided in one state and then processed into another state, for example converted from a liquid state into a solid state. Such conversion can be accomplished in a variety of ways, for example by drying, heating, or exposure to radiation. Furthermore, useful material compositions can include a set of materials that, after deposition and processing, is reduced to a subset of the set of materials, for example by removing solvents from the material composition. For example, a material composition including a solvent is deposited and then processed to remove the solvent leaving a material composition without the solvent in place. Thus, according to embodiments of the present invention, a material composition that is deposited on a layer or in the imprinted micro-cavities is not necessarily the same composition as that found in the cured material composition. 
     Methods and device for forming and providing substrates, coating substrates and other layers, patterning coated substrates or layers, or pattern-wise depositing materials on a substrate or layer are known in the photo-lithographic arts. Hardware controllers for controlling displays and software for managing display systems are all well known. All of these tools and methods can be usefully employed to design, implement, construct, and operate the present invention. Methods, tools, and devices for operating displays can be used with the present invention. 
     The present invention is useful in a wide variety of electronic devices. Such devices can include, for example, photovoltaic devices, OLED displays and lighting, LCD displays, inorganic LED displays and lighting, electrophoretic displays, and electrowetting displays. 
     The invention has been described in detail with particular reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 
     PARTS LIST 
     
         
         A cross section line 
         D 1 -D 6  depth/thickness 
         G group 
         L length 
         H height 
         O portion 
         OW portion width 
         P, P 1 , P 2  gap 
         R rib width 
         S gap 
         S 1  first gap 
         S 2  second gap 
         S 3  third gap 
         S 4  fourth gap 
         W 1 -W 6  width 
         Z light 
           5  large-format imprinted structure 
           6  display 
           8  substrate 
           10  first cured/curable layer 
           11  first cured layer surface 
           12  first micro-cavity 
           14  first cured/curable material 
           16  first pixel 
           18  first area 
           20  second cured/curable layer 
           21  second cured layer surface 
           22  second micro-cavity 
           24  second cured/curable material 
           26  second pixel 
           28  second area 
           30  third cured/curable layer 
           31  third cured layer surface 
           32  third micro-cavity 
           34  third cured/curable material 
           36  third pixel 
           38  third area 
           40  fourth cured/curable layer 
           41  fourth cured layer surface 
           42  fourth micro-cavity 
           44  fourth cured/curable material 
           48  fourth area 
           50  fifth cured layer 
           52  fifth micro-cavity 
           60  sixth cured layer 
           62  sixth micro-cavity 
           70  seventh cured layer 
           72  seventh micro-cavity 
           80  overlap 
           90  rib 
           100  provide substrate step 
           200  form patterned cured layer over surface step 
           201  form first patterned cured layer on substrate step 
           202  form second patterned cured layer on first patterned cured layer step 
           203  form second patterned cured layer on first patterned cured layer step 
           204  form second patterned cured layer on first patterned cured layer step 
           205  coat curable layer over surface step 
           210  stamp curable layer to form micro-cavities step 
           215  cure curable layer step 
           220  remove stamp step 
           225  coat cured layer surface and micro-cavities with curable material step 
           230  remove excess curable material from cured layer surface step 
           235  cure curable material step 
           240  align display pixels with micro-cavities step