Articles exhibiting patterned appearance in reflection and associated methods

Abstract

Described herein are article comrpsing a substrate and an assembly disposed on a major surface of the substrate. The assembly includes a first ink layer disposed proximate to the major surface and an intermediate layer. The first ink layer is printed with a randomized droplet distribution, while the intermediate layer is configured to reflect ambient light transmitted through the first ink layer to render a pattern in reflection when the article is viewed from the first major surface. The pattern comprises a color boundary that extends a distance of at least 5 mm and is visible to a naked eye when the first major surface is illuminated by a D65 light source. The first ink layer is printed such that, when a display panel is positioned behind the assembly and powered on to emit light through the assembly and substrate, no interference pattern is visible through the assembly and substrate.

Description

Attorney Docket No. : SP24-261PCTARTICLES EXHIBITING PATTERNED APPEARANCE IN REFLECTION AND ASSOCIATED METHODSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § Chinese Patent Application Serial No. 202411582548.1 filed on November 7, 2024, the content of which is relied upon and incorporated herein by reference in its entirety.FIELD

[0002] The disclosure relates to articles exhibiting a patterned appearance in a reflection mode via an ink layer deposited on a substrate via methods described herein to mitigate an interference pattern that can appear in a transmission mode.BACKGROUND

[0003] In various applications, it is desirable to provide an article having a patterned appearance in reflection but yet still allow for some light transmission to facilitate some level of functionality. For example, such a patterned appearance in reflection may be used to provide a seamless transition between display and non-display areas of an article in cover material applications. Deadfronting techniques may be used, for example, to hide the edges of a display panel or the like when the article is viewed from a cover surface (e.g., of a plastic or glass display cover material). It is desirable from an aesthetic or design standpoint to have a deadfronted appearance such that, when the display is off, the display and non-display areas present as indistinguishable from one other and the cover surface presents a unified appearance. Such a unified appearance is desirable in automotive interiors, including in-vehicle displays or touch interfaces, as well as other applications in consumer mobile or home electronics, including mobile devices and home appliances.

[0004] Existing deadfronting techniques typically involve the application of films or layers that lower the overall optical transmission of the entire assembly (e.g., including the display panel and cover material). It is possible, through application of such existing films or layers, to provide articles with sufficiently low optical transmission to hide various components of the assembly while also providing a unified appearance by blending a pattern exhibited by the article with surrounding materials (e.g., the article may be patterned to exhibit a woodgrain or fabric pattern in reflection). However, certain existing assemblies may fail to provide a desired appearance in reflection without adversely impacting optical transmission performance of the article to a significant extent.Attorney Docket No. : SP24-261PCT

[0005] Accordingly, an alternative deadfronting approach that provides a uniform or deadfronted appearance in reflection with improved performance in transmission is desired.SUMMARY

[0006] An aspect (1) pertains to an article comprising: a substrate comprising a first major surface and a second major surface opposite the first major surface; and an assembly disposed on the second major surface, the assembly comprising: a first ink layer disposed proximate the second major surface; and an intermediate layer positioned such that the first ink layer is disposed between the intermediate layer and the second major surface, wherein: the first ink layer is printed with a randomized droplet distribution, the intermediate layer is configured to reflect ambient light transmitted through the first ink layer back through the first ink layer and substrate to render a pattern in reflection from the ambient light when the article is viewed from the first major surface, the pattern comprises a color boundary that extends a distance of at least 5 mm and is visible to a naked eye when the first major surface is illuminated by a D65 light source, and when the display panel is positioned behind the assembly and powered on to emit light through the assembly and substrate, no interference pattern is visible through the assembly and substrate.

[0007] An aspect (2) pertains to an article according to the aspect (1), wherein the randomized droplet distribution does not exhibit linear tracks corresponding to a raster pattern of a printhead used to deposit the first ink layer.

[0008] An aspect (3) pertains to an article according to any of the aspects (l)-(2), wherein the pattern is a wood grain pattern.

[0009] An aspect (4) pertains to an article according to the aspect (3), wherein the pattern comprises a wood grain structure and a backround, the wood grain structure comprising a width of less than or equal to 500 pm.

[0010] An aspect (5) pertains to an article according to any of the aspects (l)-(4), wherein the pattern comoprises a plurality of color boundaries where the pattern transitions between different color hues at different spatial locations.

[0011] An aspect (6) pertains to an article according to any of the aspects ( l)-(5), wherein: the assembly further comprises a second ink layer positioned such that the intermediate layer is disposed between the first ink layer and the second ink layer, and the second ink layer is configured to cancel out the pattern in transmission such that the color boundary is not visible when the light is transmitted through the assembly and substrate.Attorney Docket No. : SP24-261PCT

[0012] An aspect (7) pertains to an article according to the aspect (6), wherien the second ink layer is printed with a randomized droplet distribution.

[0013] An aspect (8) pertains to an article according to any of the aspects (6)-(7), wherein the first ink layer is directly disposed on the second major surface of the substrate.

[0014] An aspect (9) pertains to an article according to the aspect (8), wherein the second ink layer is disposed either: (a) directly on the intermediate layer; or (b) on a second substrate positioned between the first ink layer and the display panel.

[0015] An aspect (10) pertains to an article according to the aspect (9), wherein the intermediate layer is one of an air gap, a layer of material exhibiting a refractive index contrast with the first ink layer, and a stack of layers of materials.

[0016] An aspect (11) pertains to a method comprising: printing a first ink layer on a second major surface of a glass substrate according to a pattern using an inkjet printhead, wherein the printing of the first ink layer occurs with at least one of a head gap that is greater than 1.5 mm, a resolution that is greater than 720x1440, and a droplet size including some droplets having a volume above 10 pL to provide a randomized droplet distribution; and positioning an intermediate layer such that the first ink layer is disposed between the intermediate layer and the second major surface to form an article, wherein: when ambient light is transmitted through substrate and the first ink layer, the ambient light reflects off the intermediate layer and is transmitted back through the first ink layer and substrate to render a pattern in reflection from the ambient light when the article is viewed from the first major surface, the pattern comprises a color boundary that extends a distance of at least 5 mm and is visible to a naked eye when the first major surface is illuminated by a D65 light source, and when a display panel is positioned behind the intermediate layer such that the intermediate layer is disposed between the first ink layer and the display panel, light emitted by the display panel is transmitted through the intermediate layer, the first ink layer, and the substrate to exhibit an appearance in transmission that is devoid of an interference pattern.

[0017] An aspect (12) pertains to a method according to the aspect (11), further comprising subjecting the second major surface to a plasma treatment prior to the printing.

[0018] An aspect (13) pertains to a method according to the aspect (11)-(12), wherein the printing occurs with a pass count that is less than or equal to 24.

[0019] An aspect (14) pertains to a method according to the aspect (13), wherein the pass count is less than or equal to 16.Attorney Docket No. : SP24-261PCT

[0020] An aspect (15) pertains to a method according to any of the aspects (11)-( 12), wherein the printing occurs with a head gap that is greater than or equal to 2.0 mm.

[0021] An aspect (16) pertains to a method according to the aspect (15), wherein the printing occurs with a resolution that is 1440x1440.

[0022] An aspect (17) pertains to a method according to any of the aspects (11)-( 16), wherein the printing occurs with the varying droplet size.

[0023] An aspect (18) pertains to a method according to any of the aspects (11)-( 17), wherein the printing occurs when the glass substrate is heated to a temperature that is greater than or equal to 25°C and less than or equal to 30°C.

[0024] An aspect (19) pertains to a method according to any of the aspects (11)-(18), further comprising printing a second image layer on the intermediate layer or a second substrate aligned with the glass substrate, wherein the second ink layer is configured to cancel out the pattern in transmission such that the color boundary is not visible when the light is transmitted through the intermediate layer, first ink layer, and substrate.

[0025] An aspect (20) pertains to a method according to the aspect (19), wherein the printing of the second ink layer occurs with at least one of a head gap that is greater than 1.5 mm, a resolution that is greater than 720x1440, and a varying droplet size to provide a second randomized droplet distribution.

[0026] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are comprised to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:

[0028] FIG. l is a perspective view of a vehicle interior with vehicle interior systems having displays, according to one or more embodiments of the present disclosure;Attorney Docket No. : SP24-261PCT

[0029] FIG. 2 schematically depicts a view of a display of a vehicle interior system through the line 2-2 depicted in FIG. 1, according to one or more embodiments of the present disclosure;

[0030] FIG. 3 A schematically depicts a view of a deadfront assembly of the display depicted in FIGS. 1-2, according to one or more embodiments of the present disclosure;

[0031] FIG. 3B schematically depicts a first plurality of regions of a first ink layer of the deadfront assembly depicted in FIG. 3 A, according to one or more embodiments of the present disclosure;

[0032] FIG. 3C schematically depicts a second plurality of regions of a second ink layer of the deadfront assembly depicted in FIG. 3B, according to one or more embodiments of the present disclosure;

[0033] FIG. 4A depicts an image of a first ink layer disposed on a transparency, according to one or more embodiments of the present disclosure;

[0034] FIG. 4B is a magnified microscope image of the first ink layer depicted in FIG. 4A, according to one or more embodiments of the present disclosure;

[0035] FIG. 4C depicts an appearance of the first ink layer depicted in FIG. 4A in transmission when a display panel transmits an image therethrough, according to one or more embodiments of the present disclosure;

[0036] FIG. 5 schematically depicts an apparatus for printing an ink layer on a substrate, according to one or more embodiments of the present disclosure;

[0037] FIG. 6 is a flow diagram of a method of providing an assembly including a first ink layer and an intermediate layer on a substrate;

[0038] FIGS. 7A, 7B, and 7C are images representing a pattern exhibited by an Example first ink layer printed in accordance with the method depicted in FIG. 6 when overlaid on three different displays, according to one or more embodiments of the present disclosure;

[0039] FIG. 7D is a magnified microscope image of the Example first ink layer, according to one or more embodiments of the present disclosure; and

[0040] FIG. 7E is an image of the appearance of the Example first ink layer when placed in an assembly with an intermediate layer and a second ink layer, according to one or more embodiments of the present disclosure.DETAILED DESCRIPTION

[0041] Referring generally to the figures, described herein are articles exhibiting a patterned appearance in a reflection mode via an ink layer deposited on a substrate with a randomized droplet distribution to mitigate an interference pattern that can appear in a transmission mode.Attorney Docket No. : SP24-261PCTThe articles include a substrate and an assembly disposed on a second major surface of the substrate. The assembly includes a first ink layer disposed proximate the second major surface and an intermediate layer positioned such that the first ink layer is disposed between the intermediate layer and the second major surface. The first ink layer is printed (e.g., on the second major surface of the substrate) with a randomized droplet distribution to render a pattern in reflection from ambient light when the article is viewed from the first major surface. As described in greater detail herein, the randomized droplet distribution is configured to prevent an interference pattern when the article is used in a transmission mode to convey an image (e.g., from a display panel) to a viewer through the assembly and substrate without substantially degrading the appearance of the article in the reflection mode. The articles described herein may find use in any application where it is desired to provide an article that deviates in appearance depending on whether the article is viewed in reflection and transmission.

[0042] Applicant has found that an interference pattern can arise when a display panel is positioned behind articles with semi-transparent ink layers (e.g. exhibiting an average transmittance from 10% to 80% from 400 nm to 700 nm). Particularly, it has been found that the arrangement of pixels in the display panel can cause an interference pattern if the distribution of droplets with which the semi-transparent ink layer is printed exhibits features (e.g., lines, gaps, and the like) that repeat in a substantially period fashion in at least one direction. For example, Applicant has found that if the ink layer exhibits a droplet distribution that exhibits linear tracks corresponding to a printhead raster pattern used to deposit the ink layer, that the interference pattern can arise. The nature of the interference pattern varies in appearance depending on the display panel, the ink layer, and any additional components present along the optical path of the light emitted by the display panel.

[0043] Accordingly, an investigation has revealed a printing technique using an inkjet printhead that can be used to print the first ink layer with a randomized droplet distribution that does not exhibit such features that repeat in a substantially periodic fashion so as mitigate the visibility of the interference pattern while maintaining the vividness in the pattern exhibited by the first ink layer in reflection from ambient light. Particularly, Applicant has found that printing of the first ink layer occurs with at least one of a head gap that is greater than 1.5 mm, a resolution that is greater than 720x1440, and a varying droplet size can provide the randomized droplet distribution described herein. As described in greater detail herein, other printing process parameters, such as keeping the number of printing passes relatively low (e.g., less than or equal to 24 passes), a plasma treatment of the surface upon which the first ink layerAttorney Docket No. : SP24-261PCT is disposed, and a relatively low process temperature (e.g., less than or equal to 30°C), can also aid in mitigating the interference pattern. Certain ones of these parameters, such as the relatively low pass count and large head gap, may tend to degrade the pattern or image rendered by the first image layer. However, Applicant has found a combination of printing parameters that mitigates the interference pattern when the article is used in a transmission mode without significantly degrading the sharpness or vividness of the image or pattern rendered by the first image layer in reflection. The printing technique described herein has been found to successfully produce ink layers rendering images with relatively fine details (e.g., a wood grain pattern exhibiting a grain structure with features on a scale of less than 500 pm has been demonstrated) in reflection without exhibiting an interference pattern in transmission with a pixelated light source.

[0044] A particular application where the articles described herein can find use is as cover materials is in automotive interior displays. In this context, it is desired to provide displays that are concealed or blend in with surrounding objects (e.g., the center console, dashboard, seat backs) when the display is off, and to present clear images to users when the display is on. The first ink layer and intermediate layer described herein aid in providing the glass article a desired appearance in reflection (e.g., from ambient light), while a second ink layer, positioned between the display panel and the intermediate layer, is configured to cancel out the pattern rendered by the first ink layer in transmission such that the pattern is not visible when light from the display panel is transmitted through the assembly and substrate. The second ink layer suppresses the appearance of the first ink layer in images transmitted through the article. Effects in the perceived color of the image rendered by the display caused by the first ink layer can be suppressed or even eliminated by incorporating a second ink layer in accordance with the present disclosure. Moreover, the articles described herein may also provide an overall optical transmission (measured from the substrate and deadfront assembly in combination) that is suitably low (e.g., an average optical transmittance from 400 nm to 700 nm of less than or equal to 60%, less than or equal to 50%, less than or equal to 50%, less than or equal to 40%, less than or equal to 30%, less than or equal to 20%, but greater than or equal to 5% or greater than or equal to 10% to allow a suitable portion of an image emitted by the display to be transmitted) so that the article hides various components of the display (e.g., display boundaries, electrical connections) from view, thereby effectively concealing the display when not in operation.Attorney Docket No. : SP24-261PCT

[0045] As used herein, the term “interference pattern” refers to a Moire pattern resulting from an ink layer being overlaid on a pixel array (e.g., associated with an LCD or OLED display panel) such that an image generated by the pixel array is transmitted through the ink layer.

[0046] The terms “optical transmission,” “percent transmission,” and “transmittance” are used interchangeably and refer to a percentage of light transmitted through an article over a wavelength range of interest. An “average transmittance” for light in a particular wavelength range is determined by averaging a measured optical transmission at all of the whole number wavelengths within that wavelength range.

[0047] As used herein, the terms “optical reflectance,” “percent reflectance,” and “reflectance” are used interchangeably and refer to a percentage of light reflected from an article over a wavelength range of interest. When a reflectance of a particular surface is mentioned, the referred-to value only applies to a single surface of the glass article (e.g., of a surface of a variable transmittance component). An “average optical reflectance” for light in a particular wavelength range is determined by averaging a measured optical reflectance at all of the whole number wavelengths within that wavelength range.

[0048] FIG. 1 shows a vehicle interior 1000 that includes three different vehicle interior systems 100, 200, 300, according to an exemplary embodiment. Vehicle interior system 100 includes a center console base 110 with a curved surface 120 including a display 130. Vehicle interior system 200 includes a dashboard base 210 with a curved surface 220 including a display 230. The dashboard base 210 typically includes an instrument panel 215 which may also include a display. Vehicle interior system 300 includes a dashboard steering wheelbase 310 with a curved surface 320 and a display 330. In one or more embodiments, the vehicle interior system may include a base that is an arm rest, a pillar, a seat back, a floorboard, a headrest, a door panel, or any portion of the interior of a vehicle that includes a curved surface. In embodiments, the displays 130, 230, 330 are flat and comprise cover glass with planar major surfaces. In embodiments, one or more of the displays 130, 230, 330 are curved, and the curved display may include curved cover glass that may be hot-formed or cold-formed to possess such curvature. For example, such embodiments may incorporate the assemblies described herein disposed on cold-formed glass substrates (e.g., either prior to or after the glass is cold-formed). Such cold-forming may involve any of the techniques described in U.S. Pre-Grant Publication No. 2019 / 0329531 Al, entitled “Laminating thin strengthened glass to curved molded plastic surface for decorative and display cover application,” U.S. Pre-Grant Publication No. 2019 / 0315648 Al, entitled “Cold-formed glass article and assembly process thereof,” U.S. Pre-Attorney Docket No. : SP24-261PCTGrant Publication No. 2019 / 0012033 Al, entitled “Vehicle interior systems having a curved cover glass and a display or touch panel and methods for forming the same,” and U.S. Patent Application No. 17 / 214,124, entitled “Curved glass constructions and methods for forming same,” which are hereby incorporated by reference in their entireties.

[0049] The embodiments of the glass articles described herein can be used in any or all of vehicle interior systems 100, 200 and 300. While FIG. 1 shows an automobile interior, the various embodiments of the vehicle interior system may be incorporated into any type of vehicle such as trains, automobiles (e.g., cars, trucks, buses and the like), seacraft (boats, ships, submarines, and the like), and aircraft (e.g., drones, airplanes, jets, helicopters and the like), including both human-piloted vehicles, semi-autonomous vehicles and fully autonomous vehicles. Further, while the description herein relates primarily to the use of the glass articles in vehicle displays, it should be understood that various embodiments discussed herein may be used in any type of display application. The present disclosure is also not limited to display applications but could be used in any deadfronting application.

[0050] FIG. 2 schematically depicts a side view of the display 230 shown in FIG. 1, according to an example embodiment where the display 230 is flat. While FIG. 2 depicts an example of the display 230, it should be understood that the displays 130, 330 described herein with respect to FIG. 1 may have structures and incorporate the articles described herein in a similar manner. The display 230 is shown to include a, article 400 comprising a substrate 450 and an assembly 460 disposed on the substrate 450. While the display 230 is flat in the embodiment depicted in FIG. 2, embodiments are also envisioned where the display 230 is curved and the article 400 comprises one or more curved surfaces (e.g., as a result of being cold-formed or hot-formed to have a suitable curved shape).

[0051] As shown in FIG. 2, the article 400 comprises at least a substrate 450, an assembly 460, and optionally includes an opaque layer 500. The substrate 450 has a first major surface 470 facing a viewer and a second major surface 480 upon which the assembly 460 is disposed. In embodiments, the assembly 460 may be attached to the second major surface 480 using a suitable optically clear adhesive. In embodiments, at least a portion of the assembly 460 (e.g., the first ink layer 602 depicted in FIG. 3A) can be disposed (e.g., using an inkjet printer) directly onto the second major surface 480 of the substrate 450. As used herein, the term "dispose" includes coating, depositing and / or forming a material onto a surface using any known method in the art. The disposed material may constitute a layer, as defined herein. As used herein, the phrase "disposed on" includes the instance of forming a material onto a surfaceAttorney Docket No. : SP24-261PCT such that the material is in direct contact with the surface and also includes the instance where the material is formed on a surface, with one or more intervening material(s) is between the disposed material and the surface. The intervening material(s) may constitute a layer, as defined herein. The term "layer" may include a single layer or may include one or more sublayers. Such sub-layers may be in direct contact with one another. The sub-layers may be formed from the same material or two or more different materials. In one or more alternative embodiments, such sub-layers may have intervening layers of different materials disposed therebetween. In one or more embodiments, a layer may include one or more contiguous and uninterrupted layers and / or one or more discontinuous and interrupted layers (i.e., a layer having different materials formed adjacent to one another). A layer or sub-layers may be formed by any known method in the art, including discrete deposition or continuous deposition processes. In one or more embodiments, the layer may be formed using only continuous deposition processes, or, alternatively, only discrete deposition processes.

[0052] In embodiments, the substrate 450 is a glass substrate that is optionally chemically strengthened and comprises a thickness of from 0.05 to 2.0 mm. Details of such glass substrates will be described herein with respect to FIG. 7. Although embodiments are preferred where the substrate 450 is a glass substrate, alternative embodiments may include a substrate constructed of an alternative material, such as a transparent plastic, such as PMMA, PMMA / PC, PMMA / PC / PMMA, polycarbonate and the like. As will also be discussed more fully below, in embodiments, when included, the opaque layer 500 is printed onto the second major surface 480 of the substrate 450. In embodiments, the opaque layer 500 is printed onto the assembly 460.

[0053] In embodiments, the article 400 comprises a functional surface layer 490. The functional surface layer 490 can be configured to provide one or more of a variety of functions. For example, the functional surface layer 490 may be optical coating configured to provide easy-to-clean performance, anti-glare properties, and / or antireflection properties. Such optical coatings can be created using single layers or multiple layers. In the case of anti-reflection functional surface layers, such layers may be formed using multiple layers having alternating high refractive index and low refractive index. Additionally, in embodiments, the functional surface layer 490 that provides easy-to-clean performance also provides enhanced feel for touch screens and / or coating / treatments to reduce fingerprints. In some embodiments, functional surface layer 490 is integral to the first surface of the substrate. For example, such functional surface layers can include an etched surface in the first surface of the substrate 450Attorney Docket No. : SP24-261PCT providing an anti-glare surface (or haze of from, e.g., 2% to 10%). In embodiments, both the first major surface 470 and the second major surface 480 of the article 400 comprise any of the functional layers described herein.

[0054] In embodiments, the opaque layer 500, when included, is constructed of a suitable ink (e.g., thermally curable ink, photocurable ink) and comprises a relatively high optical density (from 400 nm to 700 nm), e.g., an optical density of greater than 3, greater than or equal to 4, greater than or equal to 5, in order to block light transmittance. In embodiments, the opaque layer 500 is used to block light from transmitting through certain regions of the article 400. In embodiments, the opaque layer 500 obscures functional or non-decorative elements provided for the operation of the article 400. In embodiments, the opaque layer 500 is provided to outline backlit icons and / or other graphics (not depicted) so as to increase the contrast at the edges of such icons and / or graphics. The opaque layer 500 can be any color; in particular embodiments, though, the opaque layer 500 is black or gray. In embodiments, the opaque layer 500 is applied via inkjet printing, screen printing, coating, or other suitable technique over the assembly 460 and / or over the second major surface 480 of the substrate 450. Generally, the thickness of the opaque layer 500 is less than or equal to 25 pm (e.g., greater than or equal to 1.0 pm and less than or equal to 25.0 pm, greater than or equal to 5.0 pm and less than or equal to 25.0 pm, greater than or equal to 5.0 pm and less than or equal to 20.0 pm, greater than or equal to 5.0 pm and less than or equal to 10.0 pm).

[0055] In embodiments, the opaque layer 500, when included, may be directly deposited onto the second major surface 480 of the substrate 450 or assembly 460 using a suitable inkjet process. In embodiments, prior to deposition of the opaque layer 500, the second major surface 480 or assembly 460 may be primed using a suitable primer (e.g., an acryloxy silane primer) to facilitate adhesion of the opaque layer 500 to the substrate 450 or assembly 460. Any suitable treatment to the second major surface 480 may be used to facilitate adhesion of the opaque layer 500 to the substrate 450. As described herein, in embodiments, the article 400 does not include the opaque layer 500.

[0056] In embodiments, as shown in FIG. 2, the article 400 is placed over or in front of a light source 540, such that the light source 540 is placed behind the article 400 from the perspective of a viewer. The light source 540 is generally configured to emit light that is transmitted through the substrate 450 for viewing from the first major surface 470. The light source 540 comprises a pixel array and may be in the form a display panel. Exemplary display panelsAttorney Docket No. : SP24-261PCT include LED display, a quantum dot display, a laser display, a DLP MEMS chip, LCDs, OLEDs, transmissive displays, and the like.

[0057] In embodiments, the high optical density of the opaque layer 500, when included, causes the areas of the article 400 incorporating the opaque layer 500 to have relatively low optical transmission (e.g., an average transmittance of less than or equal to 1.0%, less than or equal to 0.5%, or less than or equal to 0.1% in the visible spectrum). Accordingly, the boundaries of the opaque layer 500 may define an image region 520, where the article 400 can exhibit a relatively high optical transmission to facilitate visibility of the light generated by the light source 540 when the article 400 is viewed from the first major surface 470, and a peripheral region 530, where the article 400 generally exhibits a lower optical transmission than in the image region 520 to facilitate concealment of various components (e.g., electrical connections, mechanical housings, and the like).

[0058] In the depicted embodiment, the image region 520 is circumferentially surrounded by the peripheral region 530. For example, in embodiments, the peripheral region 530 forms a border of the image region 520 and completely surrounds the image region 520. The border may comprise a uniform width around an entirety of the image region 520. Alternative embodiments, where the peripheral region 530 is non-uniform and / or does not completely surround the image region 520, are also contemplated and within the scope of the present disclosure. For example, in embodiments, the peripheral region 530 may be disposed adjacent to the image region 520 and only extend along a single side of the image region 520. The present disclosure is not limited to applications where the image region 520 of relatively high optical transmission is centrally disposed in the article 400.

[0059] In embodiments, the opaque layer 500 is omitted and the article 400 exhibits consistent optical properties (in terms of reflectance and transmittance) over an entirety of the surface area thereof. For example, in embodiments, the assembly 460 is configured such that the article 400 exhibits a uniform appearance when viewed from the first major surface 470 and the light source 540 is not emitting light. In embodiments, for example, the optical transmission of the article 400 may be low enough to hide the components of the light source 540 from view. In embodiments, the article 400 exhibits an average transmission over the wavelength range of 400 nm to 700 nm (when the light is normally incident on the substrate 450) of less than or equal to 60% (e.g., less than or equal to 50%, less than or equal to 50%, less than or equal to 40%, less than or equal to 30%, less than or equal to 20%, but greater than or equal to 5% or greater than or equal to 10%). As a result, the assembly 460 may prevent the light source 540Attorney Docket No. : SP24-261PCT from being visible to viewers when the light source 540 is not emitting light, thereby providing the article 400 a favorable appearance.

[0060] FIG. 3A schematically depicts a cross-sectional view of the assembly 460 depicted in FIG. 2, according to an example embodiment. As shown, the assembly 460 comprises an intermediate layer 600, a first ink layer 602 disposed on a first side of the intermediate layer 600, and a second ink layer 604 disposed on a second side of the intermediate layer 600. The first ink layer 602 is disposed more proximate to the second major surface 480 of the substrate 450 (see FIG. 2) than the intermediate layer 600 and the second ink layer 604. In embodiments, the first ink layer 602 is printed directly on the second major surface 480 of the substrate 450. In embodiments, the first ink layer 602 is printed on the intermediate layer 600 and the intermediate layer 600 is subsequently laminated onto the second major surface 480 such that a layer of a suitable optically transparent adhesive (not depicted) is disposed between the substrate 450 and the first ink layer 602.

[0061] The first ink layer 602 is generally configured to provide the article 400 with a desired appearance from light that is initially incident on the substrate 450, transmitted through the first ink layer 602, reflected via the intermediate layer 600, and transmitted back through the first ink layer 602 and substrate 450. The first ink layer 602 may determine an appearance of the article 400 in reflection from ambient light. That is, the intermediate layer 600 is configured to reflect ambient light transmitted through the first ink layer 602 back through the first ink layer 602 and substrate 450 to render a pattern in reflection from the ambient light when the article 400 is viewed from the first major surface 470.

[0062] In embodiments, the appearance of the article 400 in reflection is selected so that the article 400 blends in with other components surrounding the article 400 (see FIG. 2). For example, with reference to FIG. 1, the first ink layer 602 may be selected to form a pattern that matches that of the dashboard base 210 or other component surrounding the display 230 (e.g., an interior trim element). In embodiments, the pattern formed by the first ink layer 602 comprises two or more colors when light transmitted therethrough is perceived by a viewer from the side of the first major surface 470. In embodiments, the pattern formed by the first ink layer includes a relatively fine structure so that the appearance of the article 400 in reflection is selected so that the article 400 blends in with other components surrounding the article 400. For example, other components of the dashboard base 210 may exhibit a wood grain pattern, and the pattern rendered by the first ink layer 602 may include a woodgrain structure, with said woodgrain structures comprising substantially (e.g., gray) areas surroundedAttorney Docket No. : SP24-261PCT by a brown color. Such woodgrain structures may include lines or striae of the gray color having relatively narrow width (e.g., less than or equal to 500 gm) and having lengths of greater than or equal to 5 mm. As used herein, the term “length,” when referencing a pattern element, refers to a dimension of the element along a central axis of the pattern element (the central axis is an imaginary line at the midpoint between edges of the element). As used herein, the term “width,” when referencing a pattern element, refers to a minimum dimension of that pattern element taken in a direction perpendicular that in which the length is measured. Other patterns may include other fine features (e.g., a brushed metal pattern may include a brush pattern of linear features of observably different color). A leather grain design may exhibit fine structures in the form leather grain separated by narrow dark regions.

[0063] In embodiments, the first ink layer 602 is printed onto the substrate 450 or the intermediate layer 600 using a subtractive color model, such as a CMY or a CMYK color model. In such embodiments, the first ink layer 602 generally comprises a printed image where a pattern of inks is printed onto the substrate 450 or the intermediate layer 600 using a suitable printing device (e.g., an inkjet printing device) in accordance with a pixel pattern. Each pixel may be associated with a region of the first ink layer 602 where a plurality of dots of CMY inks are combined to provide a desired color appearance for that region of the first ink layer 602. The ink used for printing the first ink layer 602 (and the second ink layer 604, as described herein) can be thermal or UV cured ink. In particular, the ink may be composed of at least one or more colorants and a vehicle. The colorants can be soluble or insoluble in the vehicle. In embodiments, the colorants are dry colorants in the form of a fine powder. Such fine powders have particles that are, in embodiments, from 10 nm to 500 nm in size. Using the CMYK color model, the colorant provides cyan, magenta, yellow, and / or key (black) colors. The colorants are dissolved or suspended in the vehicle. The vehicle can serve as a binder to create adhesion to the surface upon which the ink is applied. Further, in embodiments, additives are included in the vehicle specifically for the purpose of improving adhesion to glass / plastic surfaces. Nonlimiting examples of vehicles for the colorant include propylene glycol monomethyl ether, diethylene glycol diethyl ether, dimethylacetamide, and toluene. Generally, such vehicles solidify at temperatures from 80 °C to 200 °C. In embodiments, the ink includes from 0.5% - 6% by volume of the colorant and 94% - 99.5% by volume of the vehicle.

[0064] In embodiments, the first ink layer comprises a thickness that is greater than or equal to 1 pm and less than or equal to 6 pm to provide sufficient visibility of the color pattern without inhibiting optical transmission to such an extent to prevent the light from the lightAttorney Docket No. : SP24-261PCT source 540 from being transmitted through the deadfront article in a sufficient amount. In embodiments, the optical density of the first ink layer is from 0.1 to 0.7 (e.g., from 0.1 to 0.5, from 0.3 to 0.5) so as to provide sufficient color visibility in reflection without overly obscuring the light source 540 so as to degrade display performance. The refractive index (at 550 nm) for the inks used to form the first ink layer 602 may be between 1.30 and 1.60 (e.g., greater than or equal to 1.45 and less than or equal to 1.55).

[0065] It is believed that the perceived color of the first ink layer 602 is caused by light passing through the first ink layer 602, being reflected, and again passing through the first ink layer 602. The intermediate layer 600 is configured to provide reflected light that is transmitted through the first ink layer 602 to render the pattern in the first ink layer 602 visible when ambient light is incident on the first major surface 470. The intermediate layer 600 exhibits an average reflectance of greater than or equal to 1.0% (preferable greater than or equal to 2.0 %, more preferably greater than or equal to 3.0%, and even more preferably greater than or equal to 4.0%) over a wavelength range from 400 nm to 700 nm for light initially incident on a surface of the intermediate layer 600 most proximate to the substrate (at normal incidence). In embodiments, the average reflectance of the intermediate layer 600 is less than or equal to 10.0% (e.g., less than or equal to 9.0%, less than or equal to 8.0%, less than or equal to 7.0%). It has been found that such a reflectance provides adequate light to render the pattern in the first ink layer 602 visible without overly obscuring the light source 540.

[0066] A variety of constructions for the intermediate layer 600 are contemplated and within the scope of the present disclosure. In embodiments, the intermediate layer 600 comprises a single layer of material to provide reflections at interfaces with layers adjacent thereto (e.g., the first and second ink layers 602 and 604, optically transparent adhesives). In embodiments, the first and second ink layers 602 and 604 are formed of inks comprising refractive indices (at 550 nm) that are greater than or equal to 1.45 and less than or equal to 1.55. Based on modelling , Applicant has determined that providing an intermediate layer 600 with a material having a refractive index (at 550 nm) that is greater than or equal to 1.7 or less than or equal to 1.3 (preferably greater than or equal to 1.8 and less than or equal to 1.2) provides a sufficient refractive index contrast to provide a suitable reflectance. Materials having a refractive index of greater than or equal to 1.7 can include high index glasses and metals or metallic oxides in either thin films or nanocomposite dispersions in lower-index resins. Suitable materials for such high index embodiments include, but are not limited to, Nb2Os, Nb2Os, Ta2Os, ZrCh, HfCh, SisN , SiON, Y2O3, TiC>2, and transparent conductive oxides (such as indium tin oxide).Attorney Docket No. : SP24-261PCTMaterials having a refractive index of less than 1.2 include MgF or other suitable materials (e.g., material composites, meta-materials, porous materials, such as the silica-based porous materials disclosed in Paolo Falcaro et al., “Hierarchical Porous Silica Films with Ultralow Refractive Index,” Chem. Mater. 2009, 21, 10, 2055-2061, hereby incorporated by reference in its entirety.)

[0067] Other structures for the intermediate layer 600 are also contemplated and within the scope of the present disclosure. For example, the intermediate layer can include an air gap, and the assembly 460 can include a second substrate 607 upon which the second ink layer 604 is disposed. The assembly 460 can include a support structure 605 configured to hold the first and second ink layers 602 and 604 in fixed relation relative to one another (e.g., so that the spacing between the first and second ink layers 602 and 604 is constant to aid in reducing wavefront tilting in the reflected light caused by the air gap). The second substrate 607 may be a suitable transparent material (e.g., having an average transmittance greater than or equal to 80% or greater than or equal to 90%) such as a glass (e.g., soda lime, aluminosilicate, boroaluminosilicate) or polymeric material.

[0068] In embodiments, the intermediate layer 600 comprises an additional layer of ink, or a multilayer stack including one or more layers of higher index materials 603a and one or more layers of lower index materials 603b. In embodiments, the stack can include from 2 to 20 layers of alternating ones of the layers of the one or more higher index materials 603a and the one or more lower index materials 603b. The one or more layers of lower index materials 603b can have a refractive index of less than 1.6 at 550 nm. Some examples of suitable materials for use as the one or more lower index materials 603b include glasses, polymeric materials, SiO2, AI2O3, GeO2, SiO, A10xNy, SiOxNy, SiuAlvOxNy, MgO, MgAl2O4, MgF2, BaF2, CaF2, DyFs, YbFs, YF3, CeFs, or a Ni, Cr, NiCr, or Ti-doped nanocomposite. The one or more layers of higher index materials 603a can have a refractive index of greater than 1.6 at 550 nm. Suitable materials for use as the one or more higher refractive index materials 40 include, Ta2Os, Nb2C>5, AIN, Si3N4, A10xNy, SiOxNy, HfO2, TiO2, ZrO2, Y2C>3, AhOs, MoOs, indium tin oxide and diamond-like carbon. Such an alternating stack may aid in providing a relatively flat reflection band over the wavelength range of 400 nm to 750 nm and therefore have minimal effects on the perceived color of light transmitted through the article 400.

[0069] In embodiments, the intermediate layer 600 further comprises a reflector layer 609 disposed on the second substrate 607. The reflector layer 609 may be a metallic layer or an alternating stack of high or low index materials, as described herein. The reflector layer 609Attorney Docket No. : SP24-261PCT may facilitate the utilization of a second substrate 607 that matches the refractive indices of the first and second ink layers 602 and 604, while still providing suitable reflectance to render the desired appearance in reflection.

[0070] The structure of the of the intermediate layer 600 is not particularly limiting. Any of the intermediate layer structures described in International Patent Application Number PCT / US2023 / 033693, published as WO 2024 / 072788 Al, entitled “Deadfront Articles with Multi-Layer Optical Structures and Associated Methods,” filed on September 23, 2023, hereby incorporated by reference in its entirety, may be used.

[0071] Referring still to FIG. 3A, irrespective of the particular structure used for the intermediate layer 600, the pattern in the first ink layer 602 generally provides a desired appearance in reflection by altering the optical transmission properties of the substrate 450. Light reflected from the intermediate layer 600 is transmitted through the first ink layer 602 to provide a desired appearance in reflection. More specifically, the particular spectrum of light transmitted through the first ink layer 602 may vary as a function of position to achieve a particular appearance in reflection. Such transmission variations may alter the appearance of images rendered by the light source 540 when the article 400 is viewed in transmission by introducing color distortions in the images. If the first ink layer 602 forms a pattern of two or more colors, for example, different regions of the first ink layer 602 associated with the different colors will have different transmission spectra. Such different transmission spectra can alter the perceived color of light emitted by the light source 540 in different ways so that the pattern formed in the first ink layer 602 is visible in the images rendered by the light source 540. To illustrate, in an example where the first ink layer 602 forms a woodgrain pattern, the woodgrain pattern may be visible when images generated by the light source 540 are transmitted through the article 400, which may distract viewers and degrade image quality. Put differently, while the pattern formed by the first ink layer 602 is desired to appear from reflections of ambient light when the light source 540 is off, the appearance of such a pattern within light transmitted through the article 400 is generally not desired. Changes in the optical transmission performance of the substrate 450 caused via the incorporation of the first ink layer 602 causes at least a portion of the substrate 450 (when the first ink layer 602 is disposed therein) to deviate from a desired appearance in transmission.

[0072] In view of the foregoing, the assembly 460 can incorporate the second ink layer 604 to counteract the deviations from the desired appearance in transmission associated with the first ink layer 602. The structure of the second ink layer 604 may be further understood in view ofAttorney Docket No. : SP24-261PCTFIGS 3B and 3C. FIG. 3B schematically depicts a portion of an image 606 rendered by the first ink layer 602. As shown, the first ink layer 602 comprises a first plurality of regions 608. Each of the first plurality of regions 608 may be a portion of the image 606 that is configured to exhibit a consistent color from reflected light. In embodiments, for example, each of the first plurality of regions 608 corresponds to a pixel in an image that is input into a printing device (e.g., an inkjet printing device). The size of each of the first plurality of regions 608 may depend on the manner with which the first ink layer 602 is printed (e.g., drop size, printing resolution, etc.). While the first plurality of regions 608 are depicted as being the same size and shape, it should be understood that the first plurality of regions 608 may deviate from one another in terms of size and shape due to inherent properties of the printing process.

[0073] In embodiments, at least some of the first plurality of regions 608 may deviate from one another in terms of color. For example, a region 608a may exhibit a first color (or first transmission spectrum) when light from the light source 540 is transmitted therethrough, while a region 608b may exhibit a second color (or second transmission spectrum) when light from the light source 540 is transmitted therethrough. Even if the same light from the light source 540 is emitted through both of the regions 608a and 608b, the portions of the image overlapping the regions 608a and 608b may appear to be different colors from one another. This example demonstrates how the different absorption spectra associated with the inks used to form the various regions of the first ink layer 602 can introduce unwanted color variations in images transmitted by the light source 540 through the article 400.

[0074] FIG. 3C schematically depicts a portion of an image 610 rendered by the second ink layer 604 in accordance with this example. As shown, the second ink layer 604 comprises a second plurality of regions 612. Each of the second plurality of regions 612 may be a portion of the image 610 that is configured to exhibit a consistent color. The second plurality of regions 612 generally overlap with the first plurality of regions 608 of the first ink layer 602 along an alignment axis 620 (see FIG. 3A). In embodiments, the alignment axis 620 extends in a direction perpendicular to the first and second major surfaces 470 and 480 of the substrate 450. As shown, the second ink layer 604 includes a region 612a that overlaps the region 608a of the first ink layer 602. In an example, the inks used to form the region 612a are selected to provide based on the transmission spectrum of the region 608a to cancel out the appearance of the appearance of the region 608a in transmission. Processes for computing the color needed to cancel out the first image layer are described in International Patent Application Number PCT / US2023 / 033693. Repeating such a process for each region of the image 606 of the firstAttorney Docket No. : SP24-261PCT ink layer 602 provides a pattern for the second ink layer 604 so that the second ink layer 604 is selected to provide a target appearance in transmission without significantly effecting the appearance of the article 400 when viewing reflections of ambient light.

[0075] Issues encountered when printing the first ink layer 602 and the second ink layer 604 will now be described. FIG. 4 A depicts a first ink layer 630 printed on a transparency according to an example described herein. The first ink layer 630 was printed to exhibit a woodgrain pattern, with different regions of the first ink layer 630 having different transmission spectra so that, when the first ink layer 630 is illuminated with ambient light, the woodgrain pattern is visible through the first ink layer 630. As shown, the first ink layer 630 is configured to exhibit a pattern in reflection that comprises a color boundary that extends a distance of at least 5 mm and is visible to a naked eye when illuminated by a D65 light source. The color boundary 632 represents a boundary between the brown background image and the dark wood grain structure.

[0076] In embodiments, the first ink layer 630 is printed using a subtractive color model, such as a CMY or a CMYK color model. As such, each of the first plurality of regions 608 (see FIG. 3B) may include a combination of ink droplets exhibiting the CMYK colors to render the color associated with the woodgrain pattern. The distribution accuracy of the droplets is important for determining whether the woodgrain pattern exhibits a vivid appearance (e.g., so that the woodgrain structure is not blurred). As such, the first ink layer 630 is printed with a non-uniform distribution of ink droplets to render the desired woodgrain pattern.

[0077] Applicant printed a CMYK-based woodgrain pattern ink layer similar to the first ink layer 630 depicted in FIG. 4 A using default settings on a commercially available inkjet printhead. A 3X electron microscope image of the ink layer 634, revealing characteristics of the layer’s morphology, is shown in FIG. 4B. As shown, the ink layer 634 exhibits a regular, substantially periodic pattern in that tracks 636 are present. The tracks 636 have a linear shape and are believed to correspond to the raster pattern of the printhead used to print the ink layer 634. The tracks 636 represent surface height deviations of the ink layer 634 (e.g., as a result of a lesser volume of ink being deposited in the tracks 636). Such substantially periodic surface height deviations were found to interact with a display panel when the display panel was placed behind an assembly 460 including the ink layer 434 (see FIG. 2). The display panel emitted an image through the assembly 460 and a portion of the resultant appearance is depicted in FIG. 4C. As shown, the appearance in transmission, while not exhibiting the woodgrain pattern of the ink layer 634, exhibits an interference pattern that manifests itself in linear fringes 638. The linear fringes 638 are believed to result from the diffraction effects caused by the surfaceAttorney Docket No. : SP24-261PCT height variations caused by the tracks 636 being overlaid onto the pixel array associated with the display panel. It is also believed that regular non-uniformities in the second ink layer 604 (see FIG. 3 A) can contribute to the appearance of linear fringes 638.

[0078] In view of the foregoing, Applicant developed printing techniques that can mitigate regular features in ink layers without substantially reducing the quality of images rendered by the ink layers in reflection. That is, in the context of the article 400 described herein, the printing technique was developed to randomize the distribution of ink droplets used to print the first ink layer 602 to a greater extent than in the ink layer 634 depicted in FIG. 4B, to eliminate or reduce the effects of the tracks 636 without substantially degrading the appearance of the reflective pattern rendered by the first ink layer 602. Given that the patterns desired to be rendered by the first ink layer 602 in reflection have fine features, completely randomizing the droplet distribution would not be effective for this purpose, as this would eliminate the appearance of such fine features (e.g. the wood grain structure would blend into the brown background in a woodgrain pattern). Thus, Applicant utilized an approach that tended to result in the spreading of ink droplets upon disposal, without completely blending the colors of the different regions together.

[0079] FIG. 5 schematically depicts an apparatus 700 for depositing an ink layer on the substrate 450 described herein, according to an example embodiment. As shown, the apparatus 700 includes a support 702 supporting a media, which is the substrate 450 described herein. A printhead 704 comprises one or more nozzles 706 configured to emit a plurality of ink droplets 708 onto the second major surface 480 of the substrate 450. One aspect of printing the ink layers described herein that has been found to be important is increasing the head gap 710 to be above 1.5 mm. The head gap 710 is a distance between a highest point of the media (e.g., the second major surface 480 of the substrate 450 in this example) and the printhead 704. It is believed that increasing the head gap 710 randomizes the distribution of droplets disposed on the second major surface 480 to mitigate the appearance of tracks in the resultant ink layer. However, too high of a head gap 710 can lead to blending of colors and significantly reduce the fidelity of the image rendered by the ink layer. Accordingly, in aspects, the head gap 710 should less than or equal to 4.0 mm. In aspects, printing of the first ink layer 602 and / or the second ink layer 604 described herein may comprise utilizing a suitable CMYK printhead with a head gap 710 that is greater than 1.5 mm and less than or equal to 4.0 mm. For example, the head gap 710 can be 1.6 mm, 1.7 mm, 1.8 mm 1.9 mm, 2.0 mm, 2.5 mm 3.0 mm, 4.0 mm, or any value within a range bounded by any two of such values.Attorney Docket No. : SP24-261PCT

[0080] Another factor that has been found to have an effect on the interference pattern is the volume of the plurality of ink droplets 708. Particularly, printing with a fixed droplet size of relatively low volume (e.g., less than 10 pL) should be avoided, as such small droplet size prevents adequate spreading of the droplets to mitigate the tracks. As such, it is preferred that printing the any of the ink layers described herein includes utilizing a droplet size distribution for the plurality of ink droplets 708 that includes at least some droplets having a volume above 10 pL to facilitate spreading of the ink upon disposal and providing a relatively uniform surface height for the ink layer. The droplet size distribution can either be fixed to have such a volume above 10 pL or varied over the course of printing the ink layer. For example, the droplet size can be fixed so that the droplets have a fixed volume of 12 pL, 14 pL, 16 pL, 18 pL, 20 pL, 22, pL, 24 pL, or any volume in a range bounded by any two of such values. A variable droplet size distribution, wherein the volume of the plurality of ink droplets 708 varies between at least two values can also be used. For example, the plurality if inkjet droplets can have a volume that varies from a first value (e.g., 7 pL), to a second value (e.g., 14 pL), and to a third value (e.g., 22 pL) can be used to print the first ink layer 602. Such varying drop size may beneficially provide for droplet spreading and further randomization of the droplet distribution without blending colors to a great extent.

[0081] Another factor that has been found to contribute to the interference pattern is printing resolution. Trials were conducted at a relatively low printing resolution (720x720 DPI) and did not yield favorable results in terms of interference pattern and image vividness. In aspects, printing of the first ink layer 602 and the second ink layer 604 described herein may be performed using a printing resolution greater than 720x1440 DPI (e.g., 1080x1080 PPI 1440x1440 DPI) to facilitate providing a vivid image with relatively fine features in reflection.

[0082] Another factor that has been found to contribute to the interference pattern is the pass count used in the printing. Relatively high pass counts (e.g., 32 passes, 64 passes) were found to result in the appearance of visible interference patterns in transmission. Accordingly, in embodiments, printing of the first and second ink layers 602 and 604 described herein may occur with a pass count that that is less than or equal to 24 passes, or even less than or equal to 16 passes to facilitate providing a vivid image with relatively fine features in reflection. A relatively high temperature of the substrate 450 (e.g., by using a heat plate coupled to a support 702), of above 30°C, was found to lead to poor image quality. Accordingly, in aspects, printing of the first and second ink layers 602 and 604 described herein occurs when the substrate 450 is heated to a temperature that is greater than or equal to 25°C and less than or equal to 30°C.Attorney Docket No. : SP24-261PCT

[0083] It has also been found that increasing the wettability of the media via a plasma surface treatment can aid in spreading the ink droplets to provide a uniform ink layer to mitigate the intereference pattern. An atmospheric plasma treatment apparatus can be used to reduce the water contact angle of the media to facilitate such droplet spreading. For example, when the media is the substrate 450, and the substrate 450 is made of glass material, an atmospheric plasma treatment of using a power of 500 W was found to be sufficient to reduce the water contact angle of the second major surface 480 to less than or equal to 10°. Such wettability was found to aid in mitigating the appearance of the interference pattern. Treatment times will depend on the scan rate of the plasma trreatment apparatus. Scan rates of 15 m / min, 7.5 m / min, 3.7 m / min, 1.8 m / min, and 0.8 m / min have been found suitable when the plasma treatment apparatus is scanned in a single scan pass over the substrate 450.

[0084] FIG. 6 is a flow diagram of a method 800 of fabricating a deadfront article, according to an example embodiment. The method 800 may be used to fabricate the article 400 described herein with respect to FIGS. 2-3B and to attach the light source 540 thereto. Accordingly, reference to various components depicted in FIGS. 2-3B will be used to aid in describing the method 800. At block 802, the pattern for the first ink layer 602 is determined. As described herein, the pattern for the first ink layer 602 may be determined based on a context of the article 400. Any suitable pattern (e.g., wood grain, brushed metal, carbon fiber, fabric) may be used depending on the implementation. The pattern may be determined based on an image of another structural element (e.g., a component of a dashboard, seat, trim element) to be used in conjunction with the article 400. For example, an image of a wood grain trim element may be taken and used as a target pattern for the first ink layer 602 so that the article 400 will blend in with its surrounding components. The pattern may include a matrix of RGB values to be input into a printer device for conversion via an ICC file to CMYK values to facilitate deposition of inks in the pattern using a subtractive color model.

[0085] At block 804, a pattern for the second ink layer 604 is determined such that the second ink layer is designed to cancel out variations of the first ink layer from desired optical transmission characteristics. In embodiments, the desired optical transmission characteristics are target color coordinates (e.g., XYZ values or RGB values) measured from light transmitted through the assembly 460 and the substrate 450. The light may have an illumination spectrum associated with the light source 540. At least some of the first plurality of regions 608 of pattern for the first ink layer 602 may exhibit color coordinates that deviate from desired values when illuminated by light from the light source 540 (having a particular illumination spectrum). 1Attorney Docket No. : SP24-261PCTThe pattern for the second ink layer 604 may be determined by computing an inverse color for ones of the second plurality of regions 612 based on the transmission characteristics exhibited by overlapping ones of the first plurality of regions 608 and a target value. In embodiments, XYZ or RGB values associated with the first plurality of regions 608 may be inverted and multiplied by target values for the coordinates to compute inverse values for overlapping ones of the second plurality of regions 612 of the second ink layer 604.

[0086] At blocks 806 and 807, once the patterns for the first and second ink layers 602 and 604 are determined, the first and second ink layers 602 and 604 are printed and the assembly 460 and substrate are assembled such that the intermediate layer 600 is disposed between the first and second ink layers 602 and 604. At block 808, the light source 540 is attached to the substrate 450.

[0087] Printing of the first and second ink layers 602 and 604 and attachment of the light source 540 may take a variety of forms depending on the implantation. For example, in embodiments, the intermediate layer 600 comprises a second substrate 607. The intermediate layer 600 may consist or consist essentially of the second substrate 607 in some embodiments (such that the second substrate 607 is a monolithic layer formed of the same material, which may be a uniform composition or a composite). In such embodiments, one or more of the first and second ink layers 602 and 604 can be printed onto the second substrate 607 prior to attachment to the substrate 450 (e.g., via a layer of optically clear adhesive). The first and second ink layers 602 and 604, for example, may be inkjet printed on either side of the second substrate 607 using the parameters described herein with respect to FIG. 6. The second substrate 607 can then be subsequently laminated on the light source 540 and then attached to the substrate 450. In embodiments, the first ink layer 602 is printed directly on the substrate 450 and the second ink layer is printed directly on a surface of the second substrate 607 (e.g., the surface of the second substrate 607 that is further form the substrate 450). The second substrate may be laminated to the light source 540 and subsequently attached to the light source 540.

[0088] In embodiments, the intermediate layer 600 further comprises a reflector layer 609 disposed on the second substrate 607. The reflector layer 609 may be a metallic layer or an alternating stack of high or low index materials, as described herein. Accordingly, in such embodiments, the method 800 may include depositing the reflector layer 609 on the second substrate 607 prior to deposition of the first and second ink layers 602 and 604 thereon. In embodiments, the second ink layer 604 is deposited on a third substrate (not depicted) beneathAttorney Docket No. : SP24-261PCT the reflector layer 609, and the third substrate may be laminated to the light source 540 and subsequently attached to the second substrate 607 and the substrate 450.

[0089] In embodiments, the intermediate layer 600 comprises an ink layer (e.g., a diffuse white or grey ink or a metallic ink) that is disposed between the first and second ink layers 602 and 604. In such embodiments, the first and second ink layers 602 and 604 as well as the intermediate layer 600 may be disposed on the same substrate. For example, the first and second ink layers 602 and 604 as well as the intermediate layer 600 may be disposed on the substrate 450 in direct contact with one another. That is, the first ink layer 402 may be printed directly on the second major surface 480 using the parameters described herein, the intermediate layer 600 can be printed on the first ink layer 602, and then second ink layer 604 can be printed in the intermediate layer 600 using the parameters described herein.

[0090] In embodiments, at least one of the first ink layer 602 and the intermediate layer 600 is printed on the substrate 450, while the second ink layer 604 is printed on the second substrate 607. In embodiments, the intermediate layer 600 comprises an air gap disposed between the first ink layer 602 and the second ink layer 604. In such embodiments, attaching the light source 540 to the substrate 450 may include laminating the second substrate 607 (with the second ink layer 604 printed thereon) to the light source 540 and attaching the light source 540 and second substrate 607 to the substrate 450 with the support structure 605 such that the second ink layer 604 is held in spaced relation to the substrate 450 to form the air gap.Examples

[0091] Embodiments of the present disclosure may be further understood in view of the following Example.

[0092] An ink layer was deposited directly onto a glass substrate using the following printing parameters during single layer printing: (a)1440xl440 DPI resolution; (b) 16pass; (c) uni direction; (d) various droplets (7 pL, 12pL, 14 pL); (e) 30°C heat plate; (f) 2 mm head gap (f) horizontal loading; (g) plasma treatment prior to printing. Without any additional components of the assembly 460 described herein (i.e., without the intermediate layer 600 or the second ink layer 602), the decorated substate was overlaid onto three displays to evaluate the performance in transmission: (1) a 1920x720 LCD display; (2) a 2400x1080 LCD display; and (3) a 2556x1179 OLED display. The results are shown in FIGS. 7A, 7B, and 7C, respectively. No visible Moire pattern was observed over any of the displays, demonstrating the efficacy of the printing techniques described herein. Moreover, the samples exhibited a vivid brown wood pattern with visible wood grain structures. A color boundary 850, at the edge of a wood grainAttorney Docket No. : SP24-261PCT structure and the brown background, was sharp and visible to the naked eye. The color boundary 850 was also visible in reflection with the display off from ambient light.

[0093] A 3X electron microscope image of the ink layer is shown in FIG. 7D. As shown, compared to the ink layer 634 depicted in FIG. 4B, the ink layer in accordance with this Example has a more randomized droplet distribution, with less visible surface height variations associated with the raster pattern of the printhead. It is believed that such surface height uniformity aids in the lack of Moire patterns exhibited in FIGS. 7A, 7B, and 7C.

[0094] The ink layer printed in accordance with this example was also provided with an intermediate layer 600 (a multilayer stack) and a second ink layer 602 having an inverse image pattern of the ink layer to form an assembly 460, which was overlaid onto a 2556x1176, 6.1 inch OLED display as a light source 540. The display was operated at its white point. The result (in a D65 black house) is shown in FIG. 8. As shown, in the depicted portion (overlapping the area 900 depicted in FIG. 7C), the second ink layer 602 was able to cancel out the appearance of the wood grain structure in transmission. Further, no Moire pattern was visible despite multiple patterned ink layers being overlaid onto the display. This demonstrates the efficacy of the printing techniques described herein in providing ink layers capable of exhibiting an aesthetically pleasing pattern in reflection while also cancelling out the pattern in transmission without exhibiting an interference pattern.

[0095] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred. In addition, as used herein, the article “a” is intended to comprise one or more than one component or element and is not intended to be construed as meaning only one.

[0096] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the disclosed embodiments. Since modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the embodiments may occur to persons skilled in the art, the disclosed embodiments should be construed to comprise everything within the scope of the appended claims and their equivalents.

Claims

Attorney Docket No. : SP24-261PCTClaimsWhat is claimed is:

1. An article comprising: a substrate comprising a first major surface and a second major surface opposite the first major surface; and an assembly disposed on the second major surface, the assembly comprising: a first ink layer disposed proximate the second major surface; and an intermediate layer positioned such that the first ink layer is disposed between the intermediate layer and the second major surface, wherein: the first ink layer is printed with a randomized droplet distribution, the intermediate layer is configured to reflect ambient light transmitted through the first ink layer back through the first ink layer and substrate to render a pattern in reflection from the ambient light when the article is viewed from the first major surface, the pattern comprises a color boundary that extends a distance of at least 5 mm and is visible to a naked eye when the first major surface is illuminated by a D65 light source, and when the display panel is positioned behind the assembly and powered on to emit light through the assembly and substrate, no interference pattern is visible through the assembly and substrate.

2. The article of claim 1, wherein the randomized droplet distribution does not exhibit linear tracks corresponding to a raster pattern of a printhead used to deposit the first ink layer.

3. The article of any of claims 1-2, wherein the pattern is a wood grain pattern.

4. The article of claim 3, wherein the pattern comprises a wood grain structure and a backround, the wood grain structure comprising a width of less than or equal to 500 pm.

5. The article of any of claims 1-2, wherein the pattern comoprises a plurality of color boundaries where the pattern transitions between different color hues at different spatial locations.Attorney Docket No. : SP24-261PCT6. The article of any of claims 1-2, wherein: the assembly further comprises a second ink layer positioned such that the intermediate layer is disposed between the first ink layer and the second ink layer, and the second ink layer is configured to cancel out the pattern in transmission such that the color boundary is not visible when the light is transmitted through the assembly and substrate.

7. The article of claim 6, wherien the second ink layer is printed with a randomized droplet distribution.

8. The article of claim 7, wherein the first ink layer is directly disposed on the second major surface of the substrate.

9. The article of claim 8, wherein the second ink layer is disposed either: (a) directly on the intermediate layer; or (b) on a second substrate positioned between the first ink layer and the display panel.

10. The article of claim 9, wherein the intermediate layer is one of an air gap, a layer of material exhibiting a refractive index contrast with the first ink layer, and a stack of layers of materials.

11. A method comprising: printing a first ink layer on a second major surface of a glass substrate according to a pattern using an inkjet printhead, wherein the printing of the first ink layer occurs with at least one of a head gap that is greater than 1.5 mm, a resolution that is greater than 720x1440, and a droplet size including some droplets having a volume above 10 pL to provide a randomized droplet distribution; and positioning an intermediate layer such that the first ink layer is disposed between the intermediate layer and the second major surface to form an article, wherein: when ambient light is transmitted through substrate and the first ink layer, the ambient light reflects off the intermediate layer and is transmitted back through the first ink layer and substrate to render a pattern in reflection from the ambient light when the article is viewed from the first major surface,Attorney Docket No. : SP24-261PCT the pattern comprises a color boundary that extends a distance of at least 5 mm and is visible to a naked eye when the first major surface is illuminated by a D65 light source, and when a display panel is positioned behind the intermediate layer such that the intermediate layer is disposed between the first ink layer and the display panel, light emitted by the display panel is transmitted through the intermediate layer, the first ink layer, and the substrate to exhibit an appearance in transmission that is devoid of an interference pattern.

12. The method of claim 11, further comprising subjecting the second major surface to a plasma treatment prior to the printing.

13. The method of any one of claims 11-12, wherein the printing occurs with a pass count that is less than or equal to 24.

14. The method of claim 13, wherein the pass count is less than or equal to 16.

15. The method of any one of claims 11-12, wherein the printing occurs with a head gap that is greater than or equal to 2.0 mm.

16. The method of claim 15, wherein the printing occurs with a resolution that is 1440x1440.

17. The method of any of claims 11-12, wherein the printing occurs with the varying droplet size.

18. The method of any of claims 11-12, wherein the printing occurs when the glass substrate is heated to a temperature that is greater than or equal to 25°C and less than or equal to 30°C.Attorney Docket No. : SP24-261PCT19. The method of any of claims 11-12, further comprising printing a second image layer on the intermediate layer or a second substrate aligned with the glass substrate, wherein the second ink layer is configured to cancel out the pattern in transmission such that the color boundary is not visible when the light is transmitted through the intermediate layer, first ink layer, and substrate.

20. The method of claim 19, wherein the printing of the second ink layer occurs with at least one of a head gap that is greater than 1.5 mm, a resolution that is greater than 720x1440, and a varying droplet size to provide a second randomized droplet distribution.

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