WO2022144633A1

WO2022144633A1 - Devices and systems including an electronic display, recycling light cavity, and uvc light source, and methods of disinfecting

Info

Publication number: WO2022144633A1
Application number: PCT/IB2021/061259
Authority: WO
Inventors: Timothy J. Hebrink; John A. Wheatley; Bharat R. Acharya; Tao Liu
Original assignee: 3M Innovative Properties Company
Priority date: 2021-01-04
Filing date: 2021-12-02
Publication date: 2022-07-07

Abstract

Devices (100, 200, 300) are provided, including an article (110, 210, 310) shaped to form a recycling light cavity (116, 216, 316), a UVC light source (120, 220, 320), and an electronic display (130, 230, 330). The recycling light cavity (116, 216, 316) is disposed on at least a portion of the electronic display (130, 230, 330). The article (110, 210, 310) includes an ultraviolet mirror (5) containing at least a plurality of alternating first and second optical layers (12A, 13A, 12B, 13B, 12N, 13N). The ultraviolet mirror (5) reflects ultraviolet light directed towards the ultraviolet mirror (5) from the UVC light source (120, 220, 320) in a wavelength range from 190 nm to 290 nm and transmits visible light in a wavelength range from 380 nm to 800 nm. Systems (100, 200, 300) are also provided including the article (110, 210, 310), a portable electronic device, and a UVC light source (120, 220, 320). Methods of disinfecting are further provided, including obtaining a device or system (100, 200, 300), directing UVC light at the ultraviolet mirror (5), and exposing the ultraviolet mirror (54) to ultraviolet light in a wavelength range from 190 nm to 290 nm.

Description

DEVICES AND SYSTEMS INCLUDING AN ELECTRONIC DISPLAY, RECYCLING LIGHT CAVITY, AND UVC LIGHT SOURCE, AND METHODS OF DISINFECTING

Field

[0001] The present disclosure generally relates to the use of selected wavelengths of ultraviolet (UV) light.

[0002] Ultraviolet (UV) light is useful, for example, for initiating free radical reaction chemistries used in coatings, adhesives, and polymeric materials. Ultraviolet light is also useful, for example, for disinfecting surfaces, fdters, bandages, membranes, articles, air, and liquids (e.g., water). Examples where UVC (i.e., ultraviolet C includes wavelengths in a range from 100 nanometers to 290 nanometers) disinfection could be applied include medical offices and supplies, airplane restrooms, hospital rooms and surgical equipment, schools, air and water purification, and consumer applications (e.g., toothbrush and cell phone disinfection). Prevention of infection and spread of disease, especially in high-risk environments and populations, has become increasingly more critical as pathogens mutate and develop antibiotic resistance. The availability and speed of global human travel elevates risks of rapidly developed epidemics/pandemics. Air and water disinfection is paramount to human health and preventing infectious disease. Benefits of UVC disinfection include touch-free application, and the mechanical disruption of cells at non-gene specific targets is unlikely to be overcome by pathogens via mutation to develop resistance. Surfaces being disinfected with ultraviolet light other than metal, ceramic, or glass surfaces will need protection from ultra-violet light. UVC irradiation can be applied to effectively inactivate or kill prokaryotic and eukaryotic microorganisms alike, including bacteria, viruses, fungi and molds. Bacterial strains with developed resistance to one or more antibiotics are also susceptible to UVC light. Some examples of pathogens of heightened interest include hospital acquired infections (e.g., C. diff, E. coli, MRSA, Klebsiella, influenza, mycobacteria, and enterobacteria), water and soil borne infections (e.g., giardia, legionella, and Campylobacter) and airborne infections (e.g., influenza, pneumonia, and tuberculosis).

[0003] UV light, however, can also be harmful to people and animals in varying degrees. For example, UV light sources that emit 400 nm to 500 nm wavelength light may cause long term damage to the eyes. Summary

[0004] In a first aspect, the present disclosure provides a device. The device includes a) an article shaped to form a recycling light cavity including at least two opposing reflectors; b) a UVC light source disposed within or adjacent to a first reflector of the at least two opposing reflectors of the recycling light cavity; and c) an electronic display. The recycling light cavity is disposed on at least a portion of the electronic display. The article includes an ultraviolet mirror comprised of at least a plurality of alternating first and second optical layers collectively reflecting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light having at least a 30 nm reflection band in a wavelength range from 190 nanometers (nm) to 290 nm (in some embodiments from 190 nm to 260 nm, from 200 nm to 250 nm, or from 240 nm to 290 nm), and collectively transmitting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident visible light in a wavelength range from greater than 380 nm to 700 nm, greater than 400 nm to 700 nm, or even greater than 400 nm to 800 nm. The UVC light source is configured to direct light at the ultraviolet mirror.

[0005] In a second aspect, the present disclosure provides a system. The system includes a) an article shaped to form a recycling light cavity including at least two opposing reflectors; b) a portable electronic device including an electronic device display. The electronic device display is foldable or the portable electronic device further comprises a keyboard or a cover, and a first reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of the electronic display. The system further includes c) a UVC light source disposed within or adjacent to the first reflector of the at least two opposing reflectors of the recycling light cavity. The article includes an ultraviolet mirror comprised of at least a plurality of alternating first and second optical layers collectively reflecting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light having at least a 30 nm reflection band in a wavelength range from 190 nanometers to 290 nanometers, and collectively transmitting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident visible light in a wavelength range from greater than 380 nm to 700 nm, greater than 400 nm to 700 nm, or even greater than 400 nm to 800 nm. The UVC light source is configured to direct light at the ultraviolet mirror.

[0006] In a third aspect, the present disclosure provides a method of disinfecting. The method comprises a) obtaining a device according to the first aspect or a system according to the second aspect; and b) directing UVC light from the UVC light source at the ultraviolet mirror. The method is useful, for example, for disinfecting surfaces of an electronic display, keyboard, etc., that a user typically touches when operating the device or system.

Brief Description of the Drawings

[0007] FIG. 1A is a schematic perspective view of an exemplary device preparable according to the present disclosure.

[0008] FIG. IB is a schematic cross-sectional view of an exemplary device preparable according to the present disclosure.

[0009] FIG. 2A is a schematic perspective view of an exemplary system preparable according to the present disclosure.

[0010] FIG. 2B is a schematic cross-sectional view of an exemplary system preparable according to the present disclosure.

[0011] FIG. 3 is a schematic cross-sectional view of another exemplary system preparable according to the present disclosure.

[0012] FIG. 4A is a schematic cross-sectional view of a multilayer article according to the present disclosure.

[0013] FIG. 4B is a schematic cross-sectional view of a device according to the present disclosure.

[0014] FIG. 5 is a schematic cross-sectional view of an UVC light collimator according to the present disclosure.

[0015] FIG. 6 is a flow chart of an exemplary method according to the present disclosure.

[0016] FIG. 7 is a schematic bottom view of a portion of a prototype box used in the examples.

[0017] FIG. 8A is a schematic top view of a portion of a design configuration for modeling in Example 4.

[0018] FIG. 8B is a schematic cross-sectional view of a portion of a design configuration for modeling in Example 4.

[0019] FIG. 9A is a schematic top view of a portion of a design configuration for modeling in Example 5.

[0020] FIG. 9B is a schematic cross-sectional view of a portion of a design configuration for modeling in Example 5. Detailed Description

[0021] Glossary

[0022] As used herein, “fluoropolymer” refers to any organic polymer containing fluorine.

[0023] As used herein, “incident” with respect to light refers to the light falling on or striking a material.

[0024] As used herein, the term or prefix “micro” refers to at least one dimension defining a structure or shape being in a range from 1 micrometer to 1 millimeter. For example, a microstructure may have a height or a width that is in a range from 1 micrometer to 1 millimeter.

[0025] As used herein, the term or prefix “nano” refers to at least one dimension defining a structure or a shape being less than 1 micrometer. For example, a nano-structure may have at least one of a height or a width that is less than 1 micrometer.

[0026] As used herein, “radiation” refers to electromagnetic radiation unless otherwise specified.

[0027] As used herein, “absorption” refers to a material converting the energy of light radiation to internal energy.

[0028] As used herein, “absorb” with respect to wavelengths of light encompasses both absorption and scattering, as scattered light also eventually gets absorbed.

[0029] As used herein, “scattering” with respect to wavelengths of light refers to causing the light to depart from a straight path and travel in different directions with different intensities.

[0030] As used herein, “reflectance” is the measure of the proportion of light or other radiation striking a surface at normal incidence which is reflected off it. Reflectivity typically varies with wavelength and is reported as the percent of incident light that is reflected from a surface (0 percent - no reflected light, 100 - all light reflected. Reflectivity and reflectance are used interchangeably herein.

[0031] As used herein, “reflective” and “reflectivity” refer to the property of reflecting light or radiation, especially reflectance as measured independently of the thickness of a material.

[0032] As used herein, “average reflectance” refers to reflectance averaged over a specified wavelength range.

[0033] Absorbance can be measured with methods described in ASTM E903-12 "Standard Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres". Absorbance measurements described herein were made by making transmission measurements as previously described and then calculating absorbance using Equation 1.

[0034] As used herein, the term “absorbance” with respect to a quantitative measurement refers to the base 10 logarithm of a ratio of incident radiant power to transmitted radiant power through a material. The ratio may be described as the radiant flux received by the material divided by the radiant flux transmitted by the material. Absorbance (A) may be calculated based on transmittance (T) according to Equation 1 :

A = -log₁₀ T (1)

[0035] Emissivity can be measured using infrared imaging radiometers with methods described in ASTM E 1933- 14 (2018) “Standard Practice for Measuring and Compensating for Emissivity Using Infrared Imaging Radiometers.”

[0036] The present disclosure provides devices and systems, e.g., devices including an electronic display and systems including a portable electronic device, with integrated UVC light sources for disinfecting touch surfaces covered by a visible light transparent ultraviolet mirror to more efficiently disinfect those surfaces. A visible light transparent ultraviolet mirror covering at least a portion of the display (and optionally keyboard or cover) of electronic devices advantageously decreases absorption of the UVC light and thus increases the UVC light available for disinfection. Portable electronic devices may have carrying case covers and/or keyboards also covered by visible light transparent ultraviolet mirrors and UVC light sources for disinfecting the touch surfaces when the cover is closed.

[0037] In a first aspect, a device is provided. The device comprises:

[0038] a) an article shaped to form a recycling light cavity comprising at least two opposing reflectors, the article comprising:

[0039] an ultraviolet mirror comprised of at least a plurality of alternating first and second optical layers collectively reflecting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light having at least a 30 nm reflection band in a wavelength range from 190 nanometers (nm) to 290 nm, and collectively transmitting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident visible light in a wavelength range from greater than 380 nm to 700 nm, greater than 400 nm to 700 nm, or even greater than 400 nm to 800 nm;

[0040] b) a UVC light source disposed within or adjacent to a first reflector of the at least two opposing reflectors of the recycling light cavity, wherein the UVC light source is configured to direct light at the ultraviolet mirror; and [0041] c) an electronic display, wherein the recycling light cavity is disposed on at least a portion of the electronic display.

[0042] In a second aspect, a system is provided. The system comprises:

[0043] a) an article shaped to form a recycling light cavity comprising at least two opposing reflectors, the article comprising:

[0044] an ultraviolet mirror comprised of at least a plurality of alternating first and second optical layers collectively reflecting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light having at least a 30 nm reflection band in a wavelength range from 190 nm to 290 nm, and collectively transmitting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident visible light in a wavelength range from greater than 380 nm to 700 nm, greater than 400 nm to 700 nm, or even greater than 400 nm to 800 nm;

[0045] b) a portable electronic device comprising an electronic device display, wherein the electronic device display is foldable or the portable electronic device further comprises a keyboard or a cover, wherein a first reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of the electronic display; and

[0046] c) a UVC light source disposed within or adjacent to the first reflector of the at least two opposing reflectors of the recycling light cavity, wherein the UVC light source is configured to direct light at the ultraviolet mirror.

[0047] The disclosure below relates to components of each of the device and system of the first and second aspects, respectively.

[0048] In many embodiments, the electronic display comprises a portable electronic device display. Some examples of typical electronic displays include a laptop display, a tablet display, and a smartphone display. In certain embodiments, a smartphone display comprises a foldable display. When the electronic display is a foldable display, preferably the recycling light cavity is disposed on at least a portion of two folding portions of the foldable display.

[0049] Referring to FIGS. 1A and IB, a schematic perspective view (FIG. 1A) is provided of an exemplary device or system 100 and a schematic cross-sectional view (FIG. IB) is provided of an exemplary device or system 100. To be concise, the term “device” will be used with respect to FIGS. 1A and IB but should be understood to also encompass a “system”. For instance, a device 100 comprises an article 110 shaped to form a recycling light cavity 116 comprising at least two opposing reflectors, namely a first reflector 112 and a second reflector 114. The device 100 further comprises a UVC light source 120 disposed adjacent to the first reflector 112 of the recycling light cavity 116. In this embodiment, four separate UVC light sources 120 can be seen in FIG. 1A and two separate UV light sources 120 can be seen in FIG. IB. The UVC light source 120 is configured to direct light (e.g., depicted by solid arrows coming from the UVC light source 120) at the ultraviolet mirror of the article 110. Dotted arrows going between the first reflector 112 and the opposing second reflector 114 depict light being recycled in the recycling light cavity 116.

[0050] In any device or system according to the present disclosure, the UVC source optionally comprises a plurality of individual UVC sources each disposed within or adjacent to a first reflector or a second reflector of the at least two opposing reflectors of the recycling light cavity. In some embodiments, the UVC source emits light having wavelengths between 200 nm and 285 nm, such as between 260 nm and 285 nm. A suitable UVC source includes, for instance, a light emitting diode (UED). In some embodiments, the UVC source comprises two or more (e.g., an array) of EEDs that emit at different 10 nm to 20 nm wavelength bands. Another suitable UVC light source is a mercury bulb that emits a peak irradiance at 254 nm. Typically, the UVC light source is configured to turn off when a device or system (e.g., a portable electronic device) is moved from a fully closed position to an at least partially open position. This is designed to minimize exposure to UVC light outside of the device or system.

[0051] Each of the first reflector 112 and the second reflector comprises at least an ultraviolet mirror. In particular an ultraviolet mirror comprised of at least a plurality of alternating first and second optical layers collectively reflecting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light having at least a 30 nm reflection band in a wavelength range from 190 nm to 290 nm, and collectively transmitting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident visible light in a wavelength range from greater than 380 nm to 700 nm, greater than 400 nm to 700 nm, or even greater than 400 nm to 800 nm.

[0052] The device 100 further comprises an electronic display 130 and the recycling light cavity 116 is disposed on at least a portion of the electronic display 130. In these embodiments, the electronic display 130 comprises a foldable display (e.g., including a hinge 150) and the recycling light cavity 116 is disposed on at least a portion of two folding portions of the foldable display 130, i.e., a first portion 132 and a second portion 134. When the foldable display 130 is in a folded position, as shown in FIG. IB, the first reflector 112 disposed on the first portion 132 of the (foldable) electronic display 130 is positioned opposite the second reflector 114 disposed on the second portion 134 of the electronic display 130. In these embodiments, the device 100 further comprises a first portion 142 of a portable electronic device having a major surface on which the first portion 132 of the electronic display 130 is disposed. Likewise, the device 100 further comprises a second portion 144 of a portable electronic device having a major surface on which the second portion 134 of the electronic display 130 is disposed.

[0053] In certain embodiments, a second reflector 114 of the at least two opposing reflectors of the recycling light cavity 116 is disposed on at least a portion of a second portion 134 of the foldable display 130, and the UVC light source 120 directs light at the ultraviolet mirror 112 and 114 only when the foldable display 130 is in a fully folded position.

[0054] Additionally, the device 100 of FIG. IB is disposed inside a container 160 that is shaped to define an interior cavity 162 sized to hold a portable electronic device 100. The container 160 is formed of a material that transmits no detectable amount of ultraviolet light out of the interior cavity 162, e.g., metal, plastic, ceramic (including glass), concrete, or wood. In certain embodiments, the container is formed of a heat-resistant or heat-transfer material that can withstand heat generated by absorption of certain wavelengths of light from the broadband UVC light source within the container. Often, the container is configured to be enclosed to contain the wavelengths of light reflected within the chamber, such as by including an access port or door that can be opened to insert or remove a device and closed to shut and/or seal the container. The use of such a container 160 can be advantageous in minimizing any emission of ultraviolet light out of the device 100 when the UVC light source 120 is emitting light. A container sized to hold a portable electronic device can be used with any device according to the present disclosure.

[0055] In certain embodiments, a suitable electronic display comprises a smartphone display (e.g., that is not foldable). Referring to FIGS. 2A and 2B, a schematic top view (FIG. 2A) is provided of an exemplary device or system 200 and a schematic cross-sectional view (FIG. 2B) is provided of an exemplary device or system 200. To be concise, the term “device” will be used with respect to FIGS. 2A and 2B but should be understood to also encompass a “system”. For instance, a device 200 comprises an article 210 shaped to form a recycling light cavity 216 comprising at least two opposing reflectors, namely a first reflector 214 and a second reflector 212.

[0056] In the embodiment shown in FIG. 2B, the article 210 further comprises two additional opposing reflectors, namely a third reflector 213 and a fourth reflector 215. As illustrated in FIG. 2B, each of the third reflector 213 and the fourth reflector 215 is adjacent to each of the first reflector 214 and the second reflector 212, and collectively the four reflectors form a four-sided recycling light cavity 216. An advantage to including more than two opposing reflectors can be to minimize loss of UVC light out of the device in a direction normal to the two opposing reflectors. Typically, the larger a surface that is located adjacent to and in between the two opposing reflectors, the more useful it is to include at least a third reflector on the surface. In this embodiment of a device 200 comprising a smartphone 240 comprising a smartphone display 230 and a smartphone case cover 270, the smartphone case cover 270 comprises a main cover 272, a cover side piece 274, and a cover hinge 276. Not only is there available area on each of the cover side piece 274 and the cover hinge 276, but also a reflector (or a portion of a reflector) may readily be attached to a major surface of each of the cover side piece 274 and the cover hinge 276. The recycling light cavity 216 is disposed on at least a portion of the smartphone case cover 270.

[0057] The device 200 further comprises a UVC light source 220 disposed adjacent to the second reflector 212 of the recycling light cavity 216. In this embodiment, six separate UVC light sources 120 can be seen in FIG. 2A and two separate UV light sources 220 can be seen in FIG. 2B. The UVC light source 220 is configured to direct light (e.g., depicted by solid arrows coming from the UVC light source 220) at the ultraviolet mirror of the article 210. Dotted arrows going between two or more of the first reflector 214, the opposing second reflector 212, the third reflector 213, and the opposing fourth reflector 215, depict light being recycled in the recycling light cavity 216.

[0058] The device 200 further comprises an electronic display 230 and the recycling light cavity 216 is disposed on at least a portion of the electronic display 230. When the smartphone case cover 270 is in a fully closed position, as shown in FIG. 2B, the first reflector 214 disposed on the electronic display 230 is positioned opposite the second reflector 212 disposed on the main cover 272 of the smartphone case cover 270. In some embodiments, the second reflector 212 of the at least two opposing reflectors of the recycling light cavity 216 is disposed on at least a portion of the smartphone case cover 270, and the UVC light source 220 directs light at the ultraviolet mirror 212 and 214 only when the smartphone 240 is in a fully closed position with the smartphone display 230 adjacent to the smartphone case cover 270.

[0059] The same general construction shown in FIG. 2B also applies to a tablet 240 comprising an electronic display 230 and a cover or keyboard 270. Accordingly, the recycling light cavity 216 can be disposed on at least a portion of the tablet keyboard or cover 270. Similarly, preferably the second reflector 212 of the at least two opposing reflectors of the recycling light cavity 216 is disposed on at least a portion of the tablet keyboard or cover 270, and the UVC light source 220 directs light at the ultraviolet mirror 212 and 214 only when the tablet 240 is in a fully closed position with the tablet display 230 adjacent to the tablet keyboard or cover 240.

[0060] In these embodiments, the device 200 further comprises comprising a visible light source 225 configured to emit visible light when the UVC light source 220 is emitting light. UVC light is not visible to the human eye, thus having visible light emitted has the safety benefit of informing a user that the UVC light is being emitted at that time. [0061] In these embodiments, the device 200 further comprises an activation switch 280 that causes the UVC light source 220 to emit light or to halt emitting light when a user engages the activation switch 280. For instance, the activation switch 280 can be positioned on the device 200 in a location that is accessible to a user when a system is in a fully closed position or is configured to cause the UVC light source to turn on only when the system is in a fully closed position to minimize UVC light from exiting the system. An activation switch may be useful with any device or system according to the present disclosure.

[0062] In these embodiments, the device 200 further comprises a timer 290 that causes the UVC light source 220 to turn off or halt emitting light when the timer 290 reaches a predetermined amount of time. The timer 290 is optionally a separate component of the device 200. The timer is optionally present as a program or application available, for instance, in a portable electronic device, configured to control operation of the UVC light source 220. Advantageously, a timer can save battery life for a portable electronic device by turning off the UVC light source following sufficient time to disinfect surfaces of the article 210 exposed to the UVC light. A timer may be useful with any device or system according to the present disclosure.

[0063] Referring to FIG. 3, a schematic cross-sectional view is provided of an exemplary device or system 300. To be concise, the term “device” will be used with respect to FIG. 3 but should be understood to also encompass a “system”. For instance, a device 300 comprises an article 310 shaped to form a recycling light cavity 316 comprising at least two opposing reflectors, namely a first reflector 312 and a second reflector 314. The device 300 further comprises a UVC light source 320 disposed within the first reflector 312 of the recycling light cavity 316. In this embodiment, two separate UV light sources 320 can be seen. The UVC light source 320 is configured to direct light (e.g., depicted by solid arrows coming from the UVC light source 320) at the ultraviolet mirror of the article 310. Dotted arrows going between the first reflector 312 and the opposing second reflector 314 depict light being recycled in the recycling light cavity 316.

[0064] The device 300 further comprises an electronic display 330 and the recycling light cavity 216 is disposed on at least a portion of the electronic display 330. In this embodiment, the device 300 comprises a laptop comprising a first portion 342 on which the electronic display is disposed and a second portion comprising a laptop keyboard 344. The recycling light cavity 316 is disposed on at least a portion of a laptop keyboard 344. When the laptop keyboard 344 is in a fully closed position, as shown in FIG. 3, the first reflector 312 disposed on the electronic display 330 of the laptop 342 is positioned opposite the second reflector 314 disposed on the laptop keyboard 344. Preferably, the second reflector 314 of the at least two opposing reflectors of the recycling light cavity 316 is disposed on at least a portion of a laptop keyboard 344, and the UVC light source 320 directs light at the ultraviolet mirror 312 and 314 only when the laptop is in a fully closed position with the laptop display 330 adjacent to the laptop keyboard 344.

[0065] In the embodiments shown in FIGS. IB, 2B, and 3, the ultraviolet mirror is depicted as a single layer. However, in addition to the ultraviolet mirror itself being formed of a plurality of first and second optical layers, in some embodiments one or more optional layers are included. Referring to FIG. 4A, a schematic cross-sectional view is provided of an exemplary article 100, including an ultraviolet mirror 5 comprising first optical layers 12A, 12B, 12N, second optical layers 13A, 13B, 13N and an optional absorbent layer 14 adjacent to the ultraviolet mirror 5. The article 100 optionally further comprises an adhesive layer 15 adjacent to the absorbent layer 14, wherein the absorbent layer 14 is disposed between the ultraviolet mirror 5 and the adhesive layer 15.

[0066] In some embodiments, a major surface of an optional absorbent layer 14 is in direct contact with a major surface of the ultraviolet mirror 5. In other embodiments, the article 100 comprises an air gap 11 disposed between the optional absorbent layer 14 and the ultraviolet mirror 5, as shown in the figure. For instance, an air gap can be achieved by taping the edges of the absorbent layer to the ultraviolent mirror. Attaching the two layers using adhesive tape also enables using an ultraviolet mirror having a shape that is different than the shape of the absorbent layer.

[0067] Additional optional features are provided. For instance, in some embodiments, an (e.g., outer) major surface of the ultraviolet mirror 5 may comprise a plurality of nonplanar features 19 protruding from the major surface. Any shape of nonplanar features may be suitable, (e.g., prisms, ridges, linear and/or curved polygons). In the embodiment shown, the nonplanar features 19 have a shape of a triangular prism. Such nonplanar features may be micro-structured and/or nanostructured over some or all of its surface; for example, as described in PCT International Application Publication No. WO 2019/130198 (Hebrink et al.). In some embodiments, the nanostructure may be superimposed on the micro-structure on the surface of the ultraviolet mirror. The micro-structures may be arranged as a series of alternating micro-peaks and micro-spaces. The size and shape of the micro-spaces between micro-peaks may mitigate the adhesion of dirt particles to the micro-peaks. The nano-structures may be arranged as at least one series of nanopeaks disposed on at least the micro-spaces. The micro-peaks may be more durable to environmental effects than the nano-peaks. Because the micro-peaks are spaced only by a microspace, and the micro-spaces are significantly taller than the nano-peaks, the micro-peaks may serve to protect the nano-peaks on the surface of the micro-spaces from abrasion. Moreover, the nonplanar features may act as light diffusive structures by scattering UVC light reflected from the ultraviolet mirror.

[0068] Referring to FIG. 4B, a schematic cross-sectional view is provided of an exemplary device 400. In some embodiments, the device 400 comprises a multilayer stack including an ultraviolet mirror 420 and one or more of an absorbent layer 430, an adhesive layer 440, or a protective layer 450. The one or more layers are disposed on at least a portion of an electronic display 410. As depicted in FIG. 4B, the optional protective layer 450 is an outer layer of the stack, the optional absorbent layer 430 is disposed between the electronic display 410 and the ultraviolet mirror 420, and the optional adhesive layer 440 adheres the stack of layers to the electronic display 410. Further optional adhesive layers (not shown) may be employed between any other two layers, such as between the ultraviolet mirror 420 and the optional absorbent layer 430 or between the optional protective layer 450 and the ultraviolet mirror 420. In some embodiments, an optional protective layer can be located between the ultraviolet mirror and the electronic display. Each of the ultraviolet mirror, absorbent layer, adhesive layer, and protective layer is described in detail below.

Ultraviolet Mirror

[0069] In some embodiments, the ultraviolet mirror reflects ultraviolet light having at least a 30 nm reflection band (in some embodiments, at least a 40 nm reflection band or at least a 50 nm reflection band) in a wavelength range of 190 nm to any of 270 nm, 280 nm, or 290 nm; such as from 190 nm to 280 nm, from 200 nm to 240 nm, from 250 nm to 260 nm, from 190 nm to 290 nm, or from 200 nm to 290 nm. In such embodiments, the ultraviolet mirror transmits ultraviolet light in a wavelength range greater than the upper limit of the wavelength range that is reflected, i.e., greater than 240 nm, 270 nm, greater than 280 nm, or greater than 290 nm, preferably in a wavelength range from greater than 380 nm to 700 nm, greater than 400 nm to 700 nm, or even greater than 400 nm to 800 nm. For each of these wavelengths / wavelength ranges, it is to be understood that the ultraviolet mirror is exposed to incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, and the optical layers collectively reflect at least 50, 60, 70, 80, 90, or 95 percent of the incident ultraviolet light having at least a 30 nm reflection band in the specified wavelength range; and collectively transmits at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light in the specified wavelength range.

[0070] It is to be understood that the percent of incident light absorbed refers to the amount absorbed integrated over a particular wavelength range (as opposed to the amount of a single wavelength that is absorbed). [0071] As indicated above, typically the absorption, transmission, and/or reflection is less than 100% of the total incident light. In most preferred embodiments, greater than 90 percent, 91, 92, 93, 94, 95, 96, 97, or 98 or greater, of incident light is absorbed, transmitted, and/or reflected. In some embodiments, the multilayer article has a UV reflectivity greater than 90% (in some embodiments, greater than 99%), specifically of at least a wavelength of 265 nm.

[0072] The ultraviolet mirror comprises multiple low/high index pairs of film layers, wherein each low/high index pair of layers has a combined optical thickness of 1/2 the center wavelength of the band it is designed to reflect. Stacks of such films are commonly referred to as quarterwave stacks. In some embodiments, different low/high index pairs of layers may have different combined optical thicknesses, such as where a broadband reflective optical film is desired.

Materials employed in the ultraviolet mirrors are preferably resistant to ultraviolet radiation. Many fluoropolymers and certain inorganic materials are resistant to ultraviolet radiation.

[0073] In some embodiments of the ultraviolet mirrors described herein, the at least first optical layer comprises inorganic material (e.g., at least one of zirconium oxynitride, hafhia, alumina, magnesium oxide, yttrium oxide, lanthanum fluoride, or neodymium fluoride), and wherein the second optical layer comprises inorganic material (e.g., at least one of silica, aluminum fluoride, magnesium fluoride, calcium fluoride, silica alumina oxide, or alumina doped silica). Exemplary materials are available, for example, from Materion Corporation, Mayfield Heights, OH, and Umicore Corporation, Brussels, Belgium.

[0074] In some embodiments of the ultraviolet mirrors described herein, the at least first optical layer comprises a polymeric material (e.g., at least one of polyvinylidene fluoride (PVDF), ethylene tetrafluoroethylene (ETFE)), and the second optical layer comprises polymeric material (e.g., at least one of a copolymer (THV,) or a polyethylene copolymer comprising subunits derived from tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidene fluoride (VDF), a copolymer (FEP) comprising subunits derived from tetrafluoro-ethylene (TFE) and hexafluoropropylene (HFP), or perfluoroalkoxy alkane (PF A)).

[0075] Second optical layers can comprise fluorinated copolymers materials such as at least one of fluorinated ethylene propylene copolymer (FEP); copolymers of tetrafluorethylene, hexafluoropropylene, and vinylidene fluoride (THV); copolymers of tetrafluoroethylene, hexafluoropropylene, or ethylene. Particularly useful are melt processible copolymers of tetrafluoroethylene and at least two, or even at least three, additional different comonomers.

[0076] In some embodiments, the first optical layer is a fluoropolymer and the second optical layer is a fluoropolymer. Examples of the materials that are desirable for such embodiments include ETFE/THV, PMMA/THV, PVDF/FEP, ETFE/FEP, PVDF/PFA, and ETFE/PFA. In select embodiments, the at least first optical layer comprises at least one of polyvinylidene fluoride or ethylene tetrafluoroethylene (ETFE) and the second optical layer comprises a copolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride (THV).

[0077] Exemplary melt processible copolymers of tetrafluoroethylene and other monomers discussed above include those available as copolymers of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride under the trade designations “DYNEON THV 220,” “DYNEON THV 230,” “DYNEON THV 2030,” “DYNEON THV 500,” “DYNEON THV 610,” and “DYNEON THV 815” from Dyneon LLC, Oakdale, MN; “NEOFLON EFEP” from Daikin Industries, Ltd., Osaka, Japan; “AFLAS” from Asahi Glass Co., Ltd., Tokyo, Japan; and copolymers of ethylene and tetrafluoroethylene available under the trade designations “DYNEON ET 6210A” and “DYNEON ET 6235” from Dyneon LLC; “TEFZEL ETFE” from E.I. duPont de Nemours and Co., Wilmington, DE; and “FLUON ETFE” by Asahi Glass Co., Ltd.

[0078] Ultraviolet mirrors described herein can be made using general processing techniques, such as by coextrusion of alternating polymer layers having different refractive indices, for example, as described in U.S Pat. Nos. 5,882,774 (Jonza et al.); 6,045,894 (Jonza et al.); 6,368,699 (Gilbert et al.); 6,531,230 (Weber et al.); 6,667,095 (Wheatley et al.); 6,783,349 (Neavin et al.); 7,271,951 B2 (Weber et al); 7,632,568 (Padiyath et al.); 7,652,736 (Padiyath et al.); and 7,952,805 (McGurran et al.); and PCT Publications WO 95/17303 (Ouderkirk et al.) and WO 99/39224 (Ouderkirk et al.).

[0079] Desirable techniques for providing an ultraviolet mirror with a controlled spectrum include the use of an axial rod heater control of the layer thickness values of coextruded polymer layers as described, for example, in U.S. Pat. No. 6,783,349 (Neavin et al.); timely layer thickness profile feedback during production from a layer thickness measurement tool such as an atomic force microscope (AFM), a transmission electron microscope, or a scanning electron microscope; optical modeling to generate the desired layer thickness profile; and repeating axial rod adjustments based on the difference between the measured layer profile and the desired layer profile.

[0080] The basic process for layer thickness profile control involves adjustment of axial rod zone power settings based on the difference of the target layer thickness profile and the measured layer profile. The axial rod power increase needed to adjust the layer thickness values in a given feedblock zone may first be calibrated in terms of watts of heat input per nanometer of resulting thickness change of the layers generated in that heater zone. For example, fine control of the spectrum is possible using 24 axial rod zones for 275 layers. Once calibrated, the necessary power adjustments can be calculated once given a target profile and a measured profile. The procedure is repeated until the two profiles converge. [0081] The layer thickness profile (layer thickness values) of ultraviolet mirrors described herein reflecting at least 50 percent of incident UV light over a specified wavelength range can be adjusted to be approximately a linear profile with the first (thinnest) optical layers adjusted to have about a 1/4 wave optical thickness (index times physical thickness) for 190 nm light and progressing to the thickest layers which would be adjusted to be about 1/4 wave thick optical thickness for 280 nm light or 290 nm light.

[0082] Dielectric mirrors, with optical thin film stack designs comprised of alternating thin layers of inorganic dielectric materials with refractive index contrast, are particularly suited for this. In recent decades they are used for applications in UV, Visible, NIR and IR spectral regions. Depending upon the spectral region of interest, there are specific materials suitable for that region. Also, for coating these materials, one of two forms of physical vapor deposition (PVD) are used: evaporation or sputtering. Evaporated coatings rely upon heating the coating material (evaporant) to a temperature at which it evaporates. This is followed by condensation of the vapor upon a substrate. For evaporated dielectric mirror coatings, the electron-beam deposition process is most commonly used. Sputtered coatings use energetic gas ions to bombard a material (“target”) surface, ejecting atoms which then condense on the nearby substrate. Depending upon which coating method is used, and the settings used for that method, thin film coating rate and structureproperty relationships will be strongly influenced. Ideally, coating rates should be high enough to allow acceptable process throughput and film performance, characterized as dense, low stress, void free, non-optically absorbing coated layers.

[0083] Exemplary embodiments can be designed to have peak reflectance at 275 nm, by both PVD methods. For example, coating discrete substrates by electron-beam deposition method, using HfCE as the high refractive index material and SiCE as the low refractive index material. Mirror design has alternating layers of “quarter wave optical thickness” (qwot) of each material, that are coated, layer by layer until, for example, after 9 layers the reflectance at 275 nm is > 95%. The bandwidth of this reflection peak is around 50 nm. Quarter wave optical thickness is the design wavelength, here 275 nm, divided by 4, or 68.75 nm. Physical thickness of the high refractive index layers (HfCf) is the quotient of qwot and refractive index of HfCf at 275 nm (2.25), or 30.55 nm. Physical thickness of the low refractive index layers (MgF2), with 275 nm refractive index at 1.4, is 49.1 nm. Coating a thin film stack, then, which is comprised of alternating layers of HfCf and SiCE and designed to have peak reflectance at 275 nm begins by coating layer 1 HfCf at 30.55 nm. In electron beam deposition a four-hearth evaporation source is used. Each hearth is cone-shaped and 17 cm³ volume of HfCf chunks fill it. The magnetically deflected high voltage electron beam is raster scanned over the material surface as filament current of the beam is steadily, in a pre-programmed fashion, increased. Upon completion of the preprogrammed step the HFO2 surface is heated to evaporation temperature, about 2500°C, and a source shutter opens, the HfCf vapor flux emerging from the source in a cosine-shaped distribution and condensing upon the substrate material above the source. For enhancement of coating uniformity, the substrate holders rotate during deposition. Upon reaching the prescribed coating thickness (23.2 nm) the filament current shuts off; the shutter closes and the HfCF material cools. For layer 2 the evaporation source is then rotated to a hearth containing chunks of MgF2 and a similar pre-programmed heating process begins. Here, the MgF2 surface temperature is about 950°C when the source shutter opens and, upon reaching the prescribed coating thickness (49. 1 nm), the filament current shuts off; the shutter closes and the HfCF material cools. This step-wise process is continued, layer by layer, until the total number of design layers is reached. With this optical design, as total layers are increased, from 3 to 9, the resulting peak reflectance increases accordingly, from 40% at 3 layers to > 95% at 9 layers.

[0084] Optionally, ultraviolet mirrors can be prepared in continuous roll to roll (R2R) fashion, using ZrON as the high refractive index material and SiO2 as the low refractive index material. The optical design is the same type of thin fdm stack, alternating qwot layers of the two materials. For ZrON, with refractive index at 275 nm of 2.4, the physical thickness target was 28.65 nm. For SiAlO2, here sputtered from an aluminum-doped silicon sputter target, with refractive index 1.55, the target thickness was 44.35 nm. Uayer one ZrON is DC sputtered from a pure zirconium sputter target in a gas mixture of argon, oxygen and nitrogen. Whereas argon is the primary sputtering gas, oxygen and nitrogen levels are set to achieve transparency, low absorptance and high refractive index. The fdm roll transport initially starts at a pre-determined speed, and the sputter source power is ramped to full operating power, followed by introduction of the reactive gases and then achieving steady state condition. Depending upon the length of fdm to coat, the process continues until total footage is achieved. Here, as the sputter source is orthogonal to and wider than the fdm which is being coated, the uniformity of coating thickness is quite high. Upon reaching the desired length of coated fdm the reactive gases are set to zero and the target is sputtered to a pure Zr surface state. The fdm direction is next reversed and silicon (aluminum doped) rotary pair of sputter targets has AC frequency (40 kHz) power applied in an argon sputtering atmosphere. Upon reaching steady state, oxygen reactive gas is introduced to provide transparency and low refractive index. At the pre-determined process setting and line speed the second layer is coated over the length which was coated for layer one. Again, as these sputter sources are also orthogonal to and wider than the fdm being coated, the uniformity of coating thickness is quite high. After reaching the desired length of coated film the reactive oxygen is removed and the target is sputtered in argon to a pure silicon (aluminum doped) surface state. Layers three to five or seven or nine or eleven or thirteen, depending upon peak reflectance target, are coated in this sequence. Upon completion, the film roll is removed for post-processing.

[0085] For manufacturing of these inorganic coatings, the electron beam process is best suited for coating discrete parts. Though some chambers have demonstrated R2R film coating, the layer by layer coating sequence would still be necessary. For R2R sputtering of film, it is advantageous to use a sputtering system with multiple sources located around one, or perhaps two, coating drums. Here, for a thirteen layers optical stack design, a two, or even single, machine pass process, with alternating high and low refractive index layers coated sequentially, would be feasible. How many machine passes needed would be contingent upon machine design, cost, practicality of thirteen consecutive sources, and so forth. Additionally, coating rates would need to be matched to a single film line speed.

[0086] Preferably, the ultraviolet mirror reflects at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 80 percent, 85, 90, 91, 92, 93, 94, 95, 96, 97, or at least 98 percent of incident ultraviolet light having at least a 30 nm reflection band in a wavelength range from 190 nanometers to 290 nanometers. The selection of the material combinations used in creating the ultraviolet mirror depends, for example, upon the desired bandwidth that will be reflected. Higher refractive index differences between the first optical layer polymer and the second optical layer polymer create more optical power thus enabling more reflective bandwidth per pair of layers. The number of optical layers is selected to achieve the desired optical properties using the minimum number of layers for reasons of film thickness, flexibility and economy. In the case of reflective films such as mirrors, the number of layers is preferably less than about 2,000, more preferably less than about 1,000, and even more preferably less than about 750. In some embodiments, the number of layers is at least 100, 125, 150, 175, or at least 200. The refractive index of zirconia, however, is so high that a much lower number of optical layers is needed when zirconia or zirconia oxynitride is employed, such as 50 optical layers or less, 40, 30, 20, or 15 optical layers or less; and 9 optical layers or more, 15, 17, or 20 optical layers or more, may be needed.

[0087] In some embodiments, the ultraviolet mirror has a reflection spectrum at an incident light angle of 0° (e.g., normal incidence) that shifts to shorter wavelengths at oblique angles (e.g., 15°, 30°, 45°, 60°, or 75°). One can thus prepare an ultraviolet mirror having a normal incidence spectrum such that at an intended angle of incidence, the ultraviolet mirror reflects ultraviolet light in a range of 190 nm to 290 nm. Optionally, an intervening optical element (e.g., prism, louver, or the like) is placed between the ultraviolet mirror and a UVC light source to change or limit the angle of incidence of the light emitted by the UVC light source before it reaches an exterior surface of the ultraviolet mirror. Moreover, one can form a shape of an exterior surface of the ultraviolet mirror such that the angle of incidence is maintained for various locations of the ultraviolet mirror.

Absorbent Layer

[0088] In some embodiments, the article comprises an absorbent layer that absorbs at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light over a wavelength bandwidth of at least 30 nanometers having a wavelength between at least 200 nanometers and 400 nanometers. Such an absorbent layer typically comprises a major surface and the ultraviolet mirror of the article is adjacent to the major surface of the absorbent layer. The optional absorbent layer preferably resists ultraviolet light-induced damage/degradation over time by absorbing ultraviolet light that may pass through the ultraviolet mirror. Ultraviolet light, in particular the ultraviolet radiation having wavelengths in a range from 280 nm to 400 nm, can induce degradation of plastics, which in turn results in color change and deterioration of optical and mechanical properties. Inhibition of photo-oxidative degradation is important, for instance, for maintaining long-term durability of the device or system. The absorption of ultraviolet light by polyethylene terephthalates, for example, starts at around 360 nm, increases markedly below 320 nm, and is very pronounced at below 300 nm. Polyethylene naphthalates strongly absorb ultraviolet light in the 310 nm to 370 nm range, with an absorption tail extending to about 410 nm, and with absorption maxima occurring at 352 nm and 337 nm. Chain cleavage occurs in the presence of oxygen, and the predominant photooxidation products are carbon monoxide, carbon dioxide, and carboxylic acids. Besides the direct photolysis of the ester groups, consideration has to be given to oxidation reactions, which likewise form carbon dioxide via peroxide radicals.

[0089] In general, the absorbent layer may include any polymeric composition (i.e., polymer plus additives) that is capable of withstanding ultraviolet light radiation for an extended period of time, while absorbing (including scattering) ultraviolet radiation that does not get reflected by the ultraviolet mirror. In some embodiments, the absorbent layer comprises a silicone thermoplastic, a fluoropolymer, copolymers thereof, or blends thereof. In some embodiments, the absorbent layer comprises a fluoropolymer (co)polymer comprising polymerized units derived from one or more monomers selected from tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, a perfluoroalkoxy alkylene, or a combination thereof. In this context, the term “polymer” will be understood to include homopolymers and copolymers, as well as polymers or copolymers that may be formed in a miscible blend, for example, by co-extrusion or by reaction, including transesterification. The terms “polymer” and “copolymer” also include both random and block copolymers. These polymers, suitable for the absorbent layer, tend to exhibit less degradation from exposure to ultraviolet radiation (e.g., wavelengths between 190 nm and 400 nm) than other polymers formed of different monomers.

[0090] In some embodiments, the absorbent layer comprises one or more of an ultraviolet radiation absorber, a hindered amine light stabilizer, a pigment, an anti-oxidant, or a combination thereof. Suitable ultraviolet radiation absorbers include titanium dioxide, zinc oxide, cesium dioxide, zirconium dioxide, or combinations thereof. These particular ultraviolet radiation absorbers tend to be stable to ultraviolet radiation in addition to absorbing the radiation. Suitable ultraviolet radiation absorbers further include a benzotriazole compound, a benzophenone compound, a triazine compound (e.g., including any combination thereof).

[0091] Some suitable ultraviolet radiation absorbers are red shifted UV absorbers (RUVA) which absorb at least 70% (in some embodiments, at least 80%, or even greater than 90%) of the UV light in the wavelength region from 180 nm to 400 nm. Typically, it is desirable if the RUVA is highly soluble in polymers of the absorbent layer, highly absorptive, photo-permanent and thermally stable in the temperature range from 200°C to 300°C for extrusion process to form the absorbent layer.

[0092] RUVAs typically have enhanced spectral coverage in the long-wave UV region, enabling it to block the high wavelength UV light that can cause yellowing in polyesters. Typical UV protective layers have thicknesses in a range from 13 micrometers to 380 micrometers (0.5 mil to 15 mils) with a RUVA loading level of 2-10 wt.%. One of the most effective RUVA is a benzotriazole compound, 5 -trifluoromethyl-2-(2 -hydroxy-3 -alpha-cumyl-5 -tert-octylphenyl)-2H- benzotriazole (available under the trade designation “CGU-0139” from BASF, Florham Park, NJ). Other exemplary benzotriazoles include 2-(2 -hydroxy-3, 5-di-alpha-cumylphehyl)-2H- benzotriazole, 5-chloro-2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-2H-benzotiazole, 5-chloro-2- (2 -hydroxy-3, 5 -di -tert-butylphenyl)-2H-benzotriazole, 2-(2 -hydroxy-3, 5 -di -tert-amylphenyl)-2H- benzotriazole, 2-(2-hydroxy-3-alpha-cumyl-5-tert-octylphenyl)-2H-benzotriazole, 2-(3 -tert-butyl - 2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole. Further exemplary RUVAs includes 2(- 4, 6-diphenyl- 1-3, 5 -triazin-2 -yl)-5 -hexyloxy-phenol. Other exemplary UV absorbers include those available from BASF under the trade designations “TINUVIN 1577,” “TINUVIN 900,” “TINUVIN 1600,” and “TINUVIN 777.” Other exemplary UV absorbers are available, for example, in a polyester master batch under the trade designation “TA07-07 MB” from Sukano Polymers Corporation, Dunkin, SC. An exemplary UV absorber for polymethylmethacrylate is a masterbatch available, for example, under the trade designation “TAI 1-10 MB01” from Sukano Polymers Corporation. An exemplary UV absorber for polycarbonate is a masterbatch from Sukano Polymers Corporation, under the trade designations “TA28-09 MB01.” In addition, the UV absorbers can be used in combination with hindered amine light stabilizers (HALS) and antioxidants. Exemplary HALS include those available from BASF, under the trade designation “CHIMASSORB 944” and “TINUVIN 123.” Exemplary anti-oxidants include those obtained under the trade designations “IRGANOX 1010” and “ULTRANOX 626”, also available from BASF.

[0093] Other additives may be included in an absorbent layer. Small particle non-pigmentary zinc oxide and titanium oxide can also be used as blocking or scattering additives in a UV absorbing layer. For example, nano-scale particles can be dispersed in polymer or coating substrates to minimize UV radiation degradation. The nano-scale particles are transparent to visible light while either scattering or absorbing harmful UV radiation thereby reducing damage to thermoplastics. U.S Pat. No. 5,504,134 (Palmer et al.), the disclosure of which is incorporated herein by reference, describes attenuation of polymer substrate degradation due to ultraviolet radiation through the use of metal oxide particles in a size range of about 0.001 to about 0.2 micrometer (in some embodiments, about 0.01 micrometer to about 0.15) micrometer in diameter. U.S. Pat. No. 5,876,688 (Laundon), the disclosure of which is incorporated herein by reference, describes a method for producing micronized zinc oxide that are small enough to be transparent when incorporated as UV blocking and/or scattering agents in paints, coatings, finishes, plastic articles, cosmetics and the like which are well suited for use in the present invention. These fine particles such as zinc oxide and titanium oxide with particle size ranged from 10 nm to 100 nm that can attenuate UV radiation are available, for example, from Kobo Products, Inc., South Plainfield, NJ. Flame retardants may also be incorporated as an additive in an absorbent layer.

Adhesive Layer

[0094] One or more optional adhesive layers may comprise any adhesive (e.g., thermosetting adhesive, hot melt adhesive, and/or pressure-sensitive adhesive). If present, an optional adhesive layer preferably comprises a pressure-sensitive adhesive. In some embodiments, the adhesive may be resistant to ultraviolet radiation damage. Exemplary adhesives which are typically resistant to ultraviolet radiation damage include silicone adhesives and acrylic adhesives containing UV- stabilizing/blocking additive(s), for example, as discussed hereinabove.

[0095] In many embodiments, the optional adhesive is optically clear, which means that the adhesive has both transparency and clarity (e.g., low haze). In certain embodiments, an optically clear adhesive (OCA) is selected from an acrylate, a polyurethane, a polyolefin (such as a polyisobutylene (PIB)), a silicone, or a combination thereof. Illustrative OCAs include those described in International Pub. No. WO 2008/128073 (Everaerts et al.) relating to antistatic optically clear pressure sensitive adhesives, U.S. Pat. App. Pub. Nos. US 2009/089137 (Sherman et al.) relating to stretch releasing OCA, US 2009/0087629 (Everaerts et al.) relating to indium tin oxide compatible OCA, US 2010/0028564 (Cheng et al.) relating to antistatic optical constructions having optically transmissive adhesive, US 2010/0040842 (Everaerts et al.) relating to adhesives compatible with corrosion sensitive layers, US 2011/0126968 (Dolezal et al.) relating to optically clear stretch release adhesive tape, and U.S. Pat. No. 8,557,378 (Yamanaka et al.) relating to stretch release adhesive tapes. Suitable OCAs include acrylic optically clear pressure sensitive adhesives such as, for example, 3M OCA 8146, 8211, 8212, 8213, 8214, and 8215, each available from 3M Company, St. Paul, MN.

[0096] The optional adhesive layer may comprise thermally-conductive particles to aid in heat transfer, preferably by transferring heat transversely within the adhesive layer toward the side edges of the device or system. Exemplary thermally-conductive particles include aluminum oxide particles, alumina nanoparticles, aluminum trihydrate, aluminum coated glass beads, metal silicides, graphite, graphene, carbon nanotubes, hexagonal boron nitride particles and agglomerates (e.g., available as 3M BORON DINITRIDE from 3M Company), graphene particles, graphene oxide particles, metal particles, and combinations thereof. Further, optional releasable liners used with an optional adhesive layer may comprise, for example, a polyolefin film, a fluoropolymer film, a coated PET film, or a siliconized film or paper.

Protective Layer

[0097] An optional protective layer comprises a fluoropolymer, the protective layer disposed adjacent to a major surface of the ultraviolet mirror. The protective layer is an outer layer. In some embodiments, the protective layer comprises surface structures. In some embodiments, an outer surface of the protective layer is patterned and/or is textured, e.g., including a light matte finish. In certain embodiments, a textured surface is provided for aesthetic purposes, for instance, texturing could be employed to provide the layer with a certain desired appearance.

[0098] Any suitable fluoropolymer material may be used in the protective layer. Non-limiting examples of fluoropolymers that may be used include: a polymer of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidene fluoride (for example, available under the trade designation “3M DYNEON THV” from 3M Company), a polymer of TFE, HFP, vinylidene fluoride, and perfluoropropyl vinyl ether (PPVE) (for example, available under the trade designation “3M DYNEON THVP” from 3M Company), a polyvinylidene fluoride (PVDF) (for example, “3M DYNEON PVDF 6008” available from 3M Company), an ethylene chlorotrifluoroethylene (ECTFE) polymer (for example, available under the trade designation “HALAR 350LC ECTFE” from Solvay, Brussels, Belgium), an ethylene tetrafluoroethylene (ETFE) (for example, available under the trade designation “3M DYNEON ETFE 6235” from 3M Company), a perfluoroalkoxy alkane (PF A) polymer, a fluorinated ethylene propylene (FEP) polymer, a polytetrafluoroethylene (PTFE), a polymer of TFE, HFP, and ethylene (for example, available under the trade designation “3M DYNEON HTE1705” from 3M Company), or various combinations thereof. In general, various combinations of fluoropolymers can be used. In some embodiments, the fluoropolymer includes FEP. In some embodiments, the fluoropolymer includes PFA.

[0099] Examples of suitable fluoropolymers include those available, for example, from 3M Company under the trade designations “3M DYNEON THV221GZ” (39 mol% tetrafluoroethylene, 11 mol% hexafluoropropylene, and 50 mol% vinylidene fluoride), “3M DYNEON THV2030GZ” (46.5 mol% tetrafluoroethylene, 16.5 mol% hexafluoropropylene, 35.5 mol% vinylidene fluoride, and 1.5 mol% perfluoropropyl vinyl ether), “3M DYNEON THV610GZ” (61 mol% tetrafluoroethylene, 10.5 mol% hexafluoropropylene, and 28.5 mol% vinylidene fluoride), and “3M DYNEON THV815GZ” (72.5 mol% tetrafluoroethylene, 7 mol% hexafluoropropylene, 19 mol% vinylidene fluoride, and 1.5 mol% perfluoropropyl vinyl ether). Examples of fluoropolymers also include PVDF available, for example, under the trade designations “3M DYNEON PVDF 6008” and “3M DYNEON PVDF 11010” from 3M Company; FEP available, for example, under the trade designation “3M DYNEON FLUOROPLASTIC FEP 6303Z” from 3M Company; ECTFE available, for example, under the trade designation “HALAR 350LC ECTFE” from Solvay; “NEOFLON EFEP” from Daikin Industries, Ltd., Osaka, Japan; “AFLAS” from Asahi Glass Co., Ltd., Tokyo, Japan; and copolymers of ethylene and tetrafluoroethylene available under the trade designations “DYNEON ET 6210A” and “DYNEON ET 6235” from Dyneon LLC; “TEFZEL ETFE” from E.I. duPont de Nemours and Co., Wilmington, DE; and “FLUON ETFE” by Asahi Glass Co., Ltd.

[00100] In one embodiment of a device or a system, at least one angular control element may be provided in the recycling light cavity, e.g., disposed between the UVC light source and the article. Typically, such an optional (at least one) angular control element comprises at least one of a collimator, a retroreflector, a diffuser, or a reflecting diverter, for instance a lens. In some embodiments, the angular control element comprises a solid structure, while in others it comprises a hollow structure. The angular control element may be in the form a film and is often linearly continuous. Preferably, the angular control element has rotational symmetry. In select embodiments, the angular control element comprises a concave shape. In such embodiments, the UVC light source may be disposed between the first reflector of the at least two opposing reflectors and the concave shape formed by the angular control element. [00101] In one embodiment of a device or a system, the UVC collimator is a cuspate lens that redirects light laterally via total internal reflection. Such cuspate lenses generally have a depression in the center to form the cuspate, the shape of which ensures total internal reflection and lateral redirection for incident light. One suitable cuspate lens has a cuspate-torus combination and is as described in “The Black Hole™: Cuspated waveguide-injectors and illuminators for LEDs”, Parkyn et al., Proc. SPIE 3781, Nonimaging Optics: Maximum Efficiency Light Transfer V, (6 October 1999), in section 5 (“Lighthouse” Equatorial Outputs from Hemispheric Sources).

[00102] In one embodiment of a device or a system, a UVC collimator may be provided as an angular control element in the recycling light cavity. Referring to FIG. 5, a light collimator 500 directs light 550 from the UVC light source 510 across a surface of, e.g., a portable electronic device. The UVC light collimator could be combined with a hollow light guide to more uniformly distribute light. Light collimators can be designed to collimate light from a point source can be collimated (focused) using a parabolic (elliptical) reflective optical element 520. This light collimator 500 further comprises a reflective shield 530 to minimize UVC light from the UVC light source from being initially directed away from the reflective optical element 520 so all the light gets collimated. Such UVC collimators are particularly beneficial when the UVC light source includes a cylindrical UVC lamp.

[00103] Generally, the main requirements for a light collimator are that the light source be located near the focal point of the optical element and that the source be relatively small compared with the size of the optical element. Light concentrators can be designed utilizing a surface of revolution generated from a section of an ellipse with the source at one focus and the target at the other focus of the ellipse. The source at one focus shines toward the closest vertex of the ellipse. The section of the ellipse used to generate the surface of revolution is the section defined by the latus rectum at the source and the closest vertex to the source. The latus rectum must be larger than the source so that the concentrator can collect most of the light from the source. If the source and target were points, all the light from the source would be collected at the target.

[00104] Light from a point source can be collimated (focused) using a parabolic (elliptical) reflective optical element, and one suitable collimator for the system comprises a parabolic collimator. The main requirements are that the source be located near the focal point of the optical element and that the source be relatively small compared with the size of the optical element. In most applications, the optical element must be designed for practical considerations such as the size of the light source and the allowed amount of space of the optical element. Given a source diameter Ds (width in ID) and a design volume consisting of a height Hv and diameter Dv (width in ID), it is possible to derive an equation for the shape of a near-optimum parabolic reflector:

[00106] We further need to select Hv and/or Dv such that the focus of the parabola coincides with the location of the light source at [x = Dv/2, y = 0], which is achieved by choosing:

Hv = ((Dv/2)² - (Ds/2)²) / Ds

[00107] The resulting optical element is near optimal given the physical constraints of the system. Following the etendue conservation principle, the amount of collimation is proportional to (Dv/Ds)², with higher design volumes resulting is greater collimation. The cut-off angle of this optical element is given by:

Theta = +/- atan( (Dv/2 + Ds/2) / Hv

[00108] In some embodiments, the ultraviolet mirror may comprise structures specifically for providing light diffusion. Preferably, the structures are smaller than 300 nm in each dimension, in order to be small enough to diffuse UVC light but not visible light. Such light diffusive structures may be provided by including inorganic particles. For example, each structure may correspond to one inorganic particle. The inorganic particles may be dispersed in or disposed on at least one layer of the ultraviolet mirror. The inorganic particles may comprise titania, silica, zirconia, or zinc oxide. The inorganic particles may be in the form of beads or microbeads. The inorganic particles may be formed of a ceramic material, glass, or various combinations of thereof. In some embodiments, the inorganic particles have an effective D90 particle size of at least 1 (in some embodiments, at least 3, 5, 6, 7, 8, 9, 10, or even at least 20) micrometers. In some embodiments, the inorganic particles have an effective D90 particle size of at most 40 (in some embodiments, at most 25, 20, 15, 14, 13, 12, 11, 10, 9, or even at most 8) micrometers. Surface structures may also include cross-linked polymer beads such as those under the tradename “CHEMISNOW” available from Soken Chemical & Engineering Company, Tokyo, Japan. As defined in NIST “Particle Size Characterization”, ASTM B 15-96 describes D90 as the intercept where 90% of the samples mass has particles with a diameter less than the value. For example, a D90 of 10 micrometers specifies that 90% of the samples mass includes particles with diameters less than 10 micrometers.

Methods

[00109] In a third aspect the present disclosure provides a method of disinfecting. The method comprises: [00110] a) obtaining a device according to the first aspect or a system according to the second aspect; and

[00111] b) directing UVC light from the UVC light source at the ultraviolet mirror.

[00112] In some embodiments, a system is obtained and the method further comprises placing the portable electronic device in a fully closed position to initiate step b).

[00113] As a safety measure, UVC light ceases to be emitted when the portable electronic device is not in a fully closed position, thus the method may further comprise c) halting emitting UVC light from the UVC light source by placing the portable electronic device in an at least partially open position at least one material.

[00114] FIG. 6 provides a flow chart of an exemplary method, including Step 610 to obtain a system or a device and Step 620 to direct UVC light from the UVC light source at the ultraviolet mirror. The method optionally includes Step 630 to halt emitting UVC light from the UVC light source by placing the portable electronic device in an at least partially open position.

[00115] The device is according to any of the embodiments of the device of the first aspect, described in detail above. The system is according to any of the embodiments of the system of the second aspect, described in detail above. The UVC light source is according to any of the embodiments of the UVC light source described in detail above.

[00116] In certain embodiments, step b) above is performed until achievement of a log 2, log 3, log 4, or greater reduction of at least one microorganism on or in the at least one material, as compared to an amount of the at least one microorganism present prior to step b). As used herein, the term “microorganism” refers to any cell or particle having genetic material suitable for analysis or detection (including, for example, bacteria, yeasts, viruses, and bacterial endospores). Uog reduction values (URV) may be determined by measuring the number of colonies of a microorganism present on or in a material prior to disinfection via an exemplary method, disinfecting the material using the method, measuring the number of colonies present on or in the material following disinfection, then calculating the URV based on colony counts obtained. The method of measuring the number of colony forming units (cfus) on or in a material will vary based on the form of the particular material. For instance, a solid may be swabbed, and a liquid or gas volumetrically sampled (and concentrated if necessary). The cfus may be measured, for instance, using a culture-based method, an imaging detection method, a fluorescence-based detection method, a colorimetric detection method, an immunological detection method, a genetic detection method, or a bioluminescence-based detection method. The URV is then calculated using the formula below: [00117] LRV= (Log of cfus/area or volume of pre-disinfected material) - (Log of cfus/area or volume of disinfected material)

Embodiments

[00118] In a first embodiment, the present disclosure provides a device. The device comprises a) an article shaped to form a recycling light cavity comprising at least two opposing reflectors; b) a UVC light source disposed within or adjacent to a first reflector of the at least two opposing reflectors of the recycling light cavity; and c) an electronic display, wherein the recycling light cavity is disposed on at least a portion of the electronic display. The article comprises an ultraviolet mirror comprised of at least a plurality of alternating first and second optical layers collectively reflecting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light having at least a 30 nm reflection band in a wavelength range from 190 nm to 290 nm, and collectively transmitting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident visible light in a wavelength range from greater than 380 nm to 700 nm, greater than 400 nm to 700 nm, or even greater than 400 nm to 800 nm. The UVC light source is configured to direct light at the ultraviolet mirror.

[00119] In a second embodiment, the present disclosure provides a device according to the first embodiment, wherein the electronic display comprises a portable electronic device display.

[00120] In a third embodiment, the present disclosure provides a device according to the first embodiment or the second embodiment, wherein the electronic display comprises a laptop display, a tablet display, or a smartphone display.

[00121] In a fourth embodiment, the present disclosure provides a device according to the third embodiment, wherein the smartphone display comprises a foldable display.

[00122] In a fifth embodiment, the present disclosure provides a device according to the fourth embodiment, wherein the recycling light cavity is disposed on at least a portion of two folding portions of the foldable display.

[00123] In a sixth embodiment, the present disclosure provides a device according to any of the first through third embodiments, wherein the electronic display comprises a laptop display and the recycling light cavity is disposed on at least a portion of a laptop keyboard. [00124] In a seventh embodiment, the present disclosure provides a device according to any of the first through third embodiments, wherein the electronic display comprises a tablet display and the recycling light cavity is disposed on at least a portion of a tablet keyboard or a tablet cover.

[00125] In an eighth embodiment, the present disclosure provides a device according to any of the first through third embodiments, wherein the electronic display comprises a smartphone display and the recycling light cavity is disposed on at least a portion of a smartphone case cover.

[00126] In a ninth embodiment, the present disclosure provides a device according to any of the first through eighth embodiments, wherein the UVC source comprises a light emitting diode (LED).

[00127] In a tenth embodiment, the present disclosure provides a device according to any of the first through ninth embodiments, wherein the UVC source emits light having wavelengths between 260 nanometers and 285 nanometers.

[00128] In an eleventh embodiment, the present disclosure provides a device according to any of the first through tenth embodiments, wherein the UVC source comprises a plurality of individual UVC sources each disposed within or adjacent to a first reflector or a second reflector of the at least two opposing reflectors of the recycling light cavity.

[00129] In a twelfth embodiment, the present disclosure provides a device according to any of the first through eleventh embodiments, wherein the UVC source is disposed within the first reflector of the recycling light cavity.

[00130] In a thirteenth embodiment, the present disclosure provides a device according to any of the first through eleventh embodiments, wherein the UVC source is disposed adjacent to the first reflector of the recycling light cavity.

[00131] In a fourteenth embodiment, the present disclosure provides a device according to any of the first through thirteenth embodiments, wherein the recycling light cavity is attached to the electronic display by an optically clear adhesive.

[00132] In a fifteenth embodiment, the present disclosure provides a device according to any of the first through fourteenth embodiments, wherein the article further comprises an absorbent layer that absorbs at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light over a wavelength bandwidth of at least 30 nanometers having a wavelength between at least 200 nanometers and 400 nanometers, the absorbent layer comprising a major surface, and wherein the ultraviolet mirror is adjacent to the major surface of the absorbent layer. [00133] In a sixteenth embodiment, the present disclosure provides a device according to the fifteenth embodiment, wherein the absorbent layer comprises a silicone thermoplastic, a fluoropolymer, copolymers thereof, or blends thereof.

[00134] In a seventeenth embodiment, the present disclosure provides a device according to the fifteenth embodiment or the sixteenth embodiment, wherein the absorbent layer comprises a fluoropolymer (co)polymer comprising polymerized units derived from one or more monomers selected from tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, a perfluoroalkoxy alkane, or a combination thereof.

[00135] In an eighteenth embodiment, the present disclosure provides a device according to any of the fifteenth through seventeenth embodiments, wherein the absorbent layer further comprises one or more of an ultraviolet radiation absorber, an ultraviolet radiation scatterer, a hindered amine light stabilizer, an anti-oxidant, a pigment, or a combination thereof.

[00136] In a nineteenth embodiment, the present disclosure provides a device according to any of the fifteenth through eighteenth embodiments, wherein the ultraviolet radiation absorber comprises one or more of titanium dioxide, zinc oxide, cesium dioxide, zirconium dioxide, or a combination thereof.

[00137] In a twentieth embodiment, the present disclosure provides a device according to any of the fifteenth through nineteenth embodiments, wherein the ultraviolet radiation absorber comprises a benzotriazole compound, a benzophenone compound, a triazine compound, or a combination thereof.

[00138] In a twenty-first embodiment, the present disclosure provides a device according to any of the fifteenth through twentieth embodiments, wherein the ultraviolet mirror is directly attached to the absorbent layer.

[00139] In a twenty-second embodiment, the present disclosure provides a device according to any of the fifteenth through twentieth embodiments, wherein the ultraviolet mirror is separated from the absorbent layer by an air gap.

[00140] In a twenty-third embodiment, the present disclosure provides a device according to any of the first through twenty-second embodiments, wherein the at least first optical layer comprises at least one of zirconium oxynitride, hafhia, alumina, magnesium oxide, yttrium oxide, lanthanum fluoride, or neodymium fluoride and wherein the second optical layer comprises at least one of silica, aluminum fluoride, magnesium fluoride, calcium fluoride, silica alumina oxide, or alumina doped silica. [00141] In a twenty-fourth embodiment, the present disclosure provides a device according to any of the first through twenty-second embodiments, wherein the at least first optical layer comprises at least one of polyvinylidene fluoride or polyethylene tetrafluoroethylene and wherein the second optical layer comprises fluorinated ethylene propylene (FEP) or a copolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride.

[00142] In a twenty-fifth embodiment, the present disclosure provides a device according to any of the first through twenty-fourth embodiments, wherein the ultraviolet mirror reflects at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 80 percent, at least 90 percent, at least 95 percent, or at least 98 percent of incident ultraviolet light in a wavelength range from 190 nanometers, 195 nm, or 200 nm, to 230 nanometers, 260 nm, or 280 nm, preferably from 190 nm to 260 nm, from 200 nm to 260 nm, or from 200 nm to 280 nm.

[00143] In a twenty-sixth embodiment, the present disclosure provides a device according to any of the first through twenty-fifth embodiments, wherein a major surface of the ultraviolet mirror comprises a plurality of nonplanar features protruding from the major surface.

[00144] In a twenty-seventh embodiment, the present disclosure provides a device according to any of the first through twenty-sixth embodiments, further comprising at least one angular control element disposed in the recycling light cavity.

[00145] In a twenty-eighth embodiment, the present disclosure provides a device according to the twenty-seventh embodiment, wherein the at least one angular control element comprises a film.

[00146] In a twenty-ninth embodiment, the present disclosure provides a device according to the twenty-seventh embodiment or the twenty-eighth embodiment, wherein the at least one angular control element comprises a solid structure.

[00147] In a thirtieth embodiment, the present disclosure provides a device according to the twenty-seventh embodiment or the twenty-eighth embodiment, wherein the at least one angular control element comprises a hollow structure having rotational symmetry.

[00148] In a thirty-first embodiment, the present disclosure provides a device according to any of the twenty-seventh through thirtieth embodiments, wherein the at least one angular control element has rotational symmetry.

[00149] In a thirty-second embodiment, the present disclosure provides a device according to any of the twenty-seventh through thirtieth embodiments, wherein the at least one angular control element is linearly continuous. [00150] In a thirty-third embodiment, the present disclosure provides a device according to the twenty-eighth embodiment, wherein the at least one angular control element comprises a concave shape.

[00151] In a thirty-fourth embodiment, the present disclosure provides a device according to the thirty-third embodiment, wherein the UVC light source is disposed between the first reflector of the at least two opposing reflectors and the concave shape formed by the angular control element.

[00152] In a thirty-fifth embodiment, the present disclosure provides a device according to any of the twenty-seventh through thirty-fourth embodiments, wherein the angular control element is disposed between the UVC light source and the article.

[00153] In a thirty-sixth embodiment, the present disclosure provides a device according to any of the twenty-seventh through thirty-fifth embodiments, wherein the at least one angular control element comprises at least one of a collimator, a retroreflector, a diffuser, or a reflecting diverter.

[00154] In a thirty-seventh embodiment, the present disclosure provides a device according to the thirty-sixth embodiment, wherein the at least one angular control element comprises a lens.

[00155] In a thirty-eighth embodiment, the present disclosure provides a device according to any of the first through thirty-seventh embodiments, further comprising a visible light source configured to emit visible light when the UVC light source is emitting light.

[00156] In a thirty-ninth embodiment, the present disclosure provides a device according to any of the first through thirty-eighth embodiments, wherein the article further comprises a protective layer comprising a fluoropolymer, the protective layer comprising a major surface, and wherein the ultraviolet mirror is adjacent to the major surface of the protective layer.

[00157] In a fortieth embodiment, the present disclosure provides a device according to any of the first through thirty-ninth embodiments, further comprising an activation switch that causes the UVC light source to emit light or to halt emitting light when a user engages the activation switch.

[00158] In a forty-first embodiment, the present disclosure provides a device according to any of the first through fortieth embodiments, further comprising a timer that causes the UVC light source to halt emitting light when the timer reaches a predetermined amount of time.

[00159] In a forty-second embodiment, the present disclosure provides a system. The system comprises a) an article shaped to form a recycling light cavity comprising at least two opposing reflectors; b) a portable electronic device comprising an electronic device display, wherein the electronic device display is foldable or the portable electronic device further comprises a keyboard or a cover, wherein a first reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of the electronic display; and c) a UVC light source disposed within or adjacent to the first reflector of the at least two opposing reflectors of the recycling light cavity. The article comprises an ultraviolet mirror comprised of at least a plurality of alternating first and second optical layers collectively reflecting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light in a wavelength range from 190 nanometers, 195 nm, or 200 nm, to 230 nanometers, 260 nm, or 280 nm, and collectively transmitting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident visible light in a wavelength range from greater than 380 nm to 700 nm, greater than 400 nm to 700 nm, or even greater than 400 nm to 800 nm. The UVC light source is configured to direct light at the ultraviolet mirror.

[00160] In a forty-third embodiment, the present disclosure provides a system according to the forty-second embodiment, wherein the electronic device display comprises a smartphone comprising a foldable display, wherein a second reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of a second portion of the foldable display, and wherein the UVC light source directs light at the ultraviolet mirror only when the foldable display is in a fully folded position.

[00161] In a forty-fourth embodiment, the present disclosure provides a system according to the forty-second embodiment, wherein the portable electronic device comprises a laptop, wherein the electronic device display comprises a laptop display, wherein a second reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of a laptop keyboard, and wherein the UVC light source directs light at the ultraviolet mirror only when the laptop is in a fully closed position with the laptop display adjacent to the laptop keyboard.

[00162] In a forty-fifth embodiment, the present disclosure provides a system according to the forty-second embodiment, wherein the portable electronic device comprises a tablet comprising a keyboard or a tablet cover, wherein a second reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of the tablet keyboard or the tablet cover, and wherein the UVC light source directs light at the ultraviolet mirror only when the tablet is in a fully closed position with the tablet display adjacent to the tablet keyboard or the tablet cover.

[00163] In a forty-sixth embodiment, the present disclosure provides a system according to the forty-second embodiment, wherein the portable electronic device comprises a smartphone comprising a case cover, wherein a second reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of the smartphone case cover, and wherein the UVC light source directs light at the ultraviolet mirror only when the smartphone is in a fully closed position with the smartphone display adjacent to the smartphone case cover.

[00164] In a forty-seventh embodiment, the present disclosure provides a system according to any of the forty-second through forty-sixth embodiments, wherein the UVC light source is configured to turn off when the portable electronic device is moved from a fully closed position to an at least partially open position.

[00165] In a forty-eighth embodiment, the present disclosure provides a system according to any of the forty-second through forty-seventh embodiments, further comprising a container shaped to define an interior cavity sized to hold the portable electronic device, the container formed of a material that transmits no detectable amount of ultraviolet light out of the interior cavity.

[00166] In a forty-ninth embodiment, the present disclosure provides a method of disinfecting. The method comprises a) obtaining a device according to any of the first through forty-first embodiments or a system according to any of the forty-second through forty-eighth embodiments; and b) directing UVC light from the UVC light source at the ultraviolet mirror.

[00167] In a fiftieth embodiment, the present disclosure provides a method he method according to the forty-ninth embodiment, wherein a system according to any of the forty-second through fortyeighth embodiments is obtained, and further comprises placing the portable electronic device in a fully closed position to initiate step b).

[00168] In a fifty-first embodiment, the present disclosure provides a method he method according to the forty-ninth embodiment or the fiftieth embodiment, wherein step b) is performed until achievement of a log 2, log 3, log 4, or greater reduction of at least one microorganism on a major surface of the ultraviolet mirror, as compared to an amount of the at least one microorganism present prior to step b).

[00169] In a fifty-second embodiment, the present disclosure provides a method he method according to any of the forty-ninth through fifty-first embodiments, further comprising c) halting emitting UVC light from the UVC light source by placing the portable electronic device in an at least partially open position.

[00170] Advantages and embodiments of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. All parts and percentages are by weight unless otherwise indicated. Examples

[00171] Preparative Example 1

[00172] A UVC mirror film reflecting over the range 240-310 nm was created by sputter coating an inorganic optical stack having first optical layers comprising ZrO_xN_y and second optical layers comprising SiAl_xO_y onto 100 micrometers (4 mil) thick fluoropolymer film (obtained under the trade designation “NOWOFLON THV 815” from Nowofol Kunststoffprodukte GmbH & Co. KG, Siegsdorf, Germany). The NOWOFLON THV 815 film was laminated to a heat stable polyester film (obtained under the trade designation “MELINEX ST504” from Dupont Teijin Films, Chester, VA) with an optically clear adhesive, or “OCA”, (obtained under the trade designation “3M Optically Clear Adhesive 8171” from 3M, St. Paul, MN). The heat stable polyester film absorbs wavelengths of light in the range of 200 nm to 350 nm. Visible light transparent UVC mirror films were coated in continuous roll to roll (R2R) fashion, using ZrO_xN_y as the high refractive index material and SiAl_xO_y as the low refractive index material. The optical design was alternating quarter wave thickness layers of the two materials tuned to have a peak reflectance at 275 nm. For ZrO_xN_y, with refractive index at 275 nm of 2.40, the physical thickness target was 28.65 nm. For SiAl_xO_y, here sputtered from an aluminum-doped silicon sputter target, with refractive index 1.55, the target thickness was 44.35 nm. Layer one ZrO_xN_y was DC sputtered from a pure zirconium sputter target in a gas mixture of argon, oxygen and nitrogen. Whereas argon was the primary sputtering gas, oxygen and nitrogen levels were set to achieve transparency, low absorptance and high refractive index. The film roll transport initially started at a predetermined speed, and the sputter source power was ramped to full operating power, followed by introduction of the reactive gases and then by achieving steady state condition. The sputter source was orthogonal to and wider than the film which was being coated. Upon reaching the desired length of coated film the reactive gases were set to zero and the target was sputtered to obtain a pure Zr surface state. The film direction was next reversed and silicon (aluminum doped) from a rotary pair of sputter targets had AC frequency (40 kHz) power applied in an argon sputtering atmosphere. Upon reaching steady state, oxygen reactive gas was introduced to provide transparency and low refractive index. At the pre-determined process setting and line speed the second layer was coated over the length which was coated for layer one. The sputter sources were orthogonal to and wider than the film being coated. After reaching the desired length of coated film the reactive oxygen was removed and the target was sputtered in argon to obtain a pure silicon (aluminum doped) surface state. This stepwise process was continued, layer by layer, until a total number of 9 layers was reached. Resulting peak reflectance was measured to be 95% at 275 nm when measured with a spectrophotometer (obtained under the trade designation “LAMBDA 1050 UV-VIS” from PerkinElmer, Waltham, MA).

[00173] Comparative Example 2

[00174] An 8 cm wide by 16 cm long printed circuit board was fabricated having six 265 nm high performance UVC LEDs (obtained under the trade designation “KLARAN” from Crystal IS, Green Island, NY) that were spaced apart by 2.5 cm in the width direction and 5 cm in the length direction. A prototype “control” box was fabricated with poster foam core board (obtained from ULINE, Pleasant Prairie, WI) having interior dimensions of 8 cm wide by 16 cm long by 1 cm depth and exterior dimensions of 10 cm wide by 18 cm long by 2 cm depth. Referring to FIG. 7, two 1.5 cm diameter holes were drilled in the bottom 710 of the prototype box 700 for UVC intensity measurements with a UVC radiometer (Thorlab Model PM100D with a S120VC photodiode power sensor, obtained from Thorlabs, Inc., Newton, NJ). One of the holes 722 in the bottom of the prototype box was positioned directly under one of the UVC LEDs and the other hole 724 was centered between a first UVC LED 732 and a second UVC LED 734 as shown in FIG. 7. With 40 mA of power supplied to each of the LEDs, the Thorlabs sensor measured a UVC intensity at 265 nm of 119 uW (microWatts) directly below one of the UVC LEDs. With 40 mA of power supplied to each of the LEDs, the Thorlabs sensor measured 9.6 pW when centered between the LEDs. The bottom of the prototype box was intended to simulate the surface of a smartphone with the opposing printed circuit board with UVC LEDs as the cover of a case containing the smartphone. Holes in the bottom of the prototype box were intended to measure the minimum UVC intensity on the surface of a smartphone in a smartphone case with a UVC LED illumination cover.

[00175] Example 3

[00176] A similar prototype box to that of Comparative Example 2 was fabricated and the UVC Mirror Film described in Preparative Example 1 was attached to the interior surfaces with the optically clear adhesive OCA 8171. UVC Mirror Film described in Preparative Example 1 was also attached to the flat spaces on the printed circuit board between the UVC LEDs with the OCA 8171. With 40 mA of power supplied to each of the LEDs, the Thorlabs sensor measured a UVC intensity at 265 nm of 118 pW directly below one of the UVC LEDs. With 40 mA of power supplied to each of the LEDs, the Thorlabs sensor measured 33 W when centered between the LEDs. The bottom of the prototype box was intended to simulate the surface of a smartphone with the opposing printed circuit board with UVC LEDs as the cover of a case containing the smartphone. Holes in the bottom of the prototype box were intended to measure the minimum UVC intensity on the surface of a smartphone covered with transparent UVC mirror film in a smartphone case with a UVC UED illumination cover. Minimum UVC intensity of the simulated surface of the smartphone in the smartphone case having interior surfaces covered by UVC mirror film was 344% higher than the “control” smartphone case having no UVC mirror film on its interior surfaces.

[00177] Example 4

[00178] Commercially available ray trace software (obtained under the trade designation “EIGHTTOOES” from Synopsys Inc., Mountain View, CA) was used to simulate the device performance.

[00179] Referring to FIGS. 8a and 8B, dark squares represent an UED array and grey squares represent sensors. The structures enclosed by the dashed square represents the unit cell used in the optical model. In this Example, LEDs and sensors are located on the opposite sides of the cavity.

[00180] The UV LED was a 0.875 mm square with Lambertian output. The UV LED was assumed to absorb light perfectly. The sensors were 1 mm square and were located half-way between LEDs since this region is typically the most difficult to illuminate. The Reflectivity of UVC mirror film lined on the cavity top and bottom was set to 80% in the model.

[00181] The irradiance on the sensors, in units of W/mm², and normalized by the LED power, is shown in Table 1. Given LED power and UVC dose requirement, it can be easily calculated what LED pitch and cavity thickness are needed. FIG. 8a depicts the LED array (top view) and FIG. 8B depicts the model (side view). Table 1 provides the data for irradiance absorbed by the absorber vs. LED pitch and cavity height.

[00182] Table 1. UVC Irradiance (W/mm²)

[00183] Example 5

[00184] Example 5 was performed similarly to Example 4, except that the LEDs and sensors were located on the same side of the cavity, as shown in FIG. 9B. [00185] The irradiance on the absorbers, in units ofW/mm², and normalized by the LED power, is shown in Table 2. Given LED power and UVC dose requirement, it can be easily calculated what LED pitch and cavity thickness are needed. The irradiance of Example 5 is slightly lower than that in Example 4 because UVC light must bounce off the UVC mirror on the cavity top before it can reach the sensors between the LEDs on the same side. FIG. 9A depicts the LED array (top view) and FIG. 9B depicts the model (side view). Table 2 provides the data for irradiance absorbed by the absorber vs. LED pitch and cavity height. [00186] Table 2. UVC Irradiance (W/mm²)

[00187] Foreseeable modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention. This invention should not be restricted to the embodiments that are set forth in this application for illustrative purposes.

Claims

38 What is claimed is:

1. A device comprising: a) an article shaped to form a recycling light cavity comprising at least two opposing reflectors, the article comprising: an ultraviolet mirror comprised of at least a plurality of alternating first and second optical layers collectively reflecting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light having at least a 30 nm reflection band in a wavelength range from 190 nanometers (nm) to 290 nm, and collectively transmitting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident visible light in a wavelength range from greater than 380 nm to 700 nm, greater than 400 nm to 700 nm, or even greater than 400 nm to 800 nm; b) a UVC light source disposed within or adjacent to a first reflector of the at least two opposing reflectors of the recycling light cavity, wherein the UVC light source is configured to direct light at the ultraviolet mirror; and c) an electronic display, wherein the recycling light cavity is disposed on at least a portion of the electronic display.

2. The device of claim 1, wherein the electronic display comprises a portable electronic device display.

3. The device of claim 1 or claim 2, wherein the electronic display comprises a smartphone display, wherein the smartphone display comprises a foldable display and the recycling light cavity is disposed on at least a portion of two folding portions of the foldable display.

4. The device of any of claims 1 to 3, wherein the electronic display comprises a laptop display and the recycling light cavity is disposed on at least a portion of a laptop keyboard.

5. The device of any of claims 1 to 3, wherein the electronic display comprises a tablet display and the recycling light cavity is disposed on at least a portion of a tablet keyboard or a tablet cover. 39

6. The device of any of claims 1 to 3, wherein the electronic display comprises a smartphone display and the recycling light cavity is disposed on at least a portion of a smartphone case cover.

7. The device of any of claims 1 to 6, wherein the UVC source comprises a light emitting diode (LED).

8. The device of any of claims 1 to 7, wherein the UVC source emits light having wavelengths between 260 nanometers and 285 nanometers.

9. The device of any of claims 1 to 8, wherein the article further comprises an absorbent layer that absorbs at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light over a wavelength bandwidth of at least 30 nanometers having a wavelength between at least 200 nanometers and 400 nanometers, the absorbent layer comprising a major surface, and wherein the ultraviolet mirror is adjacent to the major surface of the absorbent layer.

10. The device of claim 9, wherein the absorbent layer further comprises one or more of an ultraviolet radiation absorber, an ultraviolet radiation scatterer, a hindered amine light stabilizer, an anti-oxidant, a pigment, or a combination thereof.

11. The device of any of claims 1 to 10, further comprising at least one angular control element disposed in the recycling light cavity, wherein the at least one angular control element comprises at least one of a collimator, a retroreflector, a diffuser, or a reflecting diverter.

12. The device of any of claims 1 to 11, further comprising a visible light source configured to emit visible light when the UVC light source is emitting light.

13. The device of any of claims 1 to 12, wherein the article further comprises a protective layer comprising a fluoropolymer, the protective layer comprising a major surface, and wherein the ultraviolet mirror is adjacent to the major surface of the protective layer.

14. The device of any of claims 1 to 13, further comprising an activation switch that causes the UVC light source to emit light or to halt emitting light when a user engages the activation switch.

15. The device of any of claims 1 to 14, further comprising a timer that causes the UVC light source to halt emitting light when the timer reaches a predetermined amount of time. 40 A system comprising: a) an article shaped to form a recycling light cavity comprising at least two opposing reflectors, the article comprising: an ultraviolet mirror comprised of at least a plurality of alternating first and second optical layers collectively reflecting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet light having at least a 30 nm reflection band in a wavelength range from 190 nm to 290 nm, and collectively transmitting at an incident light angle of at least one of 0°, 15°, 30°, 45°, 60°, or 75°, at least 50, 60, 70, 80, 90, or 95 percent of incident visible light in a wavelength range from greater than 380 nm to 700 nm, greater than 400 nm to 700 nm, or even greater than 400 nm to 800 nm; b) a portable electronic device comprising an electronic device display, wherein the electronic device display is foldable or the portable electronic device further comprises a keyboard or a cover, wherein a first reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of the electronic display; and c) a UVC light source disposed within or adjacent to the first reflector of the at least two opposing reflectors of the recycling light cavity, wherein the UVC light source is configured to direct light at the ultraviolet mirror. The system of claim 16, wherein the electronic device display comprises a smartphone comprising a foldable display, wherein a second reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of a second portion of the foldable display, and wherein the UVC light source directs light at the ultraviolet mirror only when the foldable display is in a fully folded position. The system of claim 16, wherein the portable electronic device comprises a laptop, wherein the electronic device display comprises a laptop display, wherein a second reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of a laptop keyboard, and wherein the UVC light source directs light at the ultraviolet mirror only when the laptop is in a fully closed position with the laptop display adjacent to the laptop keyboard. The system of claim 16, wherein the portable electronic device comprises a tablet comprising a keyboard or a tablet cover, wherein a second reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of the tablet keyboard or the tablet cover, and wherein the UVC light source directs light at the ultraviolet mirror only when the tablet is in a fully closed position with the tablet display adjacent to the tablet keyboard or the tablet cover. The system of claim 16, wherein the portable electronic device comprises a smartphone comprising a case cover, wherein a second reflector of the at least two opposing reflectors of the recycling light cavity is disposed on at least a portion of the smartphone case cover, and wherein the UVC light source directs light at the ultraviolet mirror only when the smartphone is in a fully closed position with the smartphone display adjacent to the smartphone case cover. The system of any of claims 16 to 20, wherein the UVC light source is configured to turn off when the portable electronic device is moved from a fully closed position to an at least partially open position. A method of disinfecting, the method comprising: a) obtaining a device of any of claims 1 to 15 or a system of any of claims 16 to 21; and b) directing UVC light from the UVC light source at the ultraviolet mirror. The method of claim 22, wherein a system of any of claims 16 to 21 is obtained and further comprises placing the portable electronic device in a fully closed position to initiate step b).