Diffusion coating for lighting units

Abstract

A lighting unit (14, 15) is disclosed. The lighting unit (14, 15) includes a light source (11) held within a housing (10). The housing has an outer coating (17) including a polymeric material having dispersed therein a particulate material that diffuses light emitted from the light source. Preferably, the particulate material is selected from polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), and mixtures thereof. The particulate material is selected from titanium dioxide, glass beads, or white inorganic powders such as barium sulfate and magnesia.

Description

[Technical Field]

[0001] This invention relates to a coating for light-emitting diode (LED) lighting tubes and similar devices that diffuses and reduces the spotlight and glare (sometimes called dazzle) generated by individual LEDs within the unit. The spotlight is generated by the spacing between individual LEDs when they are arranged on a substrate or strip. This coating is specifically intended for use with LED light sources, allowing transmission of ultraviolet (UV) light in the wavelength ranges of 315-400 nm (UV-A), 280-315 nm (UV-B), and 100-280 nm (UV-C). It is also suitable for visible light LEDs in the wavelength range of 400-700 nm. [Background technology]

[0002] Traditional lighting fixtures, such as incandescent and fluorescent lamps, have a transparent housing surrounding a light source (such as a bulb or tube). During the manufacturing process, coatings are often applied to either or both of the interior and exterior surfaces of the housing. Coatings reduce glare, provide uniform light, and protect people near the light source from ultraviolet light emitted by the light source. Various materials are known to be used as coatings depending on the housing material. For example, in the case of glass housings, one method of forming a coating on the outside of the tube is to dissolve acrylic monomers or resins in an organic solvent. Transparent silicone particles can also be dispersed in this solvent, if desired. The solvent is then removed, accompanied by the necessary polymerization reaction, leaving behind the coating. Summary of the Invention [Problem to be solved by the invention]

[0003] The drawbacks of this method are that many of the most suitable solvents are toxic and require equipment to safely remove and recover the removed solvent. Alternatively, water-based systems can be used, but the energy costs for removing the water are often higher compared to organic solvents, and they often require the polymerization of monomers to form the coating.

[0004] A similar solution to the above problem involves fastening a preformed tube or film of material around the housing. Materials such as polyethylene terephthalate (PET) are available as preformed tubes that slide over the glass housing or are wrapped around the housing. This material can contain particulate materials that help diffuse light to the user. One drawback of such coatings is that PET materials are susceptible to degradation from heat and UV light. Under these conditions, the coating's transmittance decreases, and it can become brittle and flake off, potentially causing lamp failure and environmental pollution.

[0005] Traditional coatings also aim to block ultraviolet (UV) wavelength radiation, which can be harmful to people around lighting devices. This is often achieved by converting UV radiation into visible light (400nm-700nm) through fluorescence or phosphorescence. Even when coatings transmit UV light, it is difficult to produce coatings that transmit specific wavelengths or multiple wavelengths (reducing UV-A transmission by up to 60%) and to control the thickness of the coating applied.

[0006] The present invention addresses the above-mentioned challenges by providing a coating that enables the production of products that reduce the effects of "spotting," a phenomenon in which scattered light creates bright or dark areas on the LED lamp depending on its location within the lighting unit. The coating provided by the present invention also functions as a shatterproof or glass-shard-retaining coating that meets the requirements of IEC 61549, "Shatterproof Safety Lamps," which requires all glass fluorescent lamps to have a shatterproof coating to ensure a glass-free environment in food processing and related industries. [Means for solving the problem]

[0007] According to a first aspect of the present invention, there is provided a lighting unit comprising a light source held within a housing, the housing having an outer coating comprising a polymeric material, the coating having dispersed therein a particulate material that diffuses light emitted from the light source. The coating acts to diffuse and / or prevent transmission of light of selected wavelengths, as well as aid in retaining debris and preventing the ingress of water, insects, and other substances harmful to the lighting unit. For example, the coating can be selected to transmit wavelengths of 315-400 nm (UV-A), 280-315 nm (UV-B), and 100-280 nm (UV-C), as well as visible light from 400 nm to 700 nm, and can also act to diffuse light radiation to more uniformly distribute radiation in the vicinity of the lighting unit.

[0008] The polymer material is preferably selected from fluoropolymers such as polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), including mixtures thereof. Preferred polymer materials are perfluorinated materials. Materials such as polycarbonate (PC) and polyethylene terephthalate (PET) are less suitable for UAV light sources due to material degradation, but are suitable for white LED lamps.

[0009] The polymer material is preferably an ethylene / propylene copolymer, particularly a perfluorinated ethylene / propylene copolymer, most preferably a tetrafluoroethylene-hexafluoropropylene copolymer. The fluoropolymer coating preferably has a refractive index of 1.30 to 1.60, such as PVDF (1.443), PCTFE (1.435), ETFE (1.4), FEP (1.344), PFA (1.34), PTFE (1.356), THV (1.35), PC (1.586), and PET (1.575).

[0010] The particulate material is selected from light-diffusing particles such as metal oxide particles such as titanium dioxide, glass beads, white inorganic powders such as barium sulfate and magnesia, or mixtures thereof. The particulate material is preferably barium sulfate, and is more preferably present in the coating at 0.5 to 5.0% w / w. The average particle size of the particulate material is preferably 3.0 μm to 30.0 μm, and particularly preferably 0.7 μm. In another embodiment, the average particle size of the particulate material is less than 0.02 nm. The particulate material preferably has a refractive index of 1.00 to 2.30, such as titanium dioxide particles (refractive index 2.65), glass beads (refractive index 1.5 to 2.4), white inorganic powder barium sulfate (refractive index 1.64), magnesia (refractive index 1.00 to 111.734 at 632 nm), and titania (refractive index 1.55 to 2.3).

[0011] The light source is preferably an LED light source from the viewpoint of energy efficiency and durability. The thickness of the coating is preferably 180.0 to 500.0 μm.

[0012] According to a second aspect of the present invention, there is provided a coating for a lighting unit. The coating comprises a polymeric material formed from fluorinated ethylene propylene copolymer (FEP) having barium sulfate (BaSO4) dispersed therein, and is applied to the exterior surface of the housing to diffuse emitted light and give it a uniformly distributed appearance. The barium sulfate is preferably present in the coating at a concentration of 0.5 to 5.0% w / w. The average particle size of the barium sulfate is preferably selected from the range of 3 to 30 μm, more preferably 0.7 μm. In another embodiment, the average particle size is less than 0.02 nm. The thickness of the coating is preferably 180 to 500 μm, more preferably 200 to 300 μm.

[0013] According to a third aspect of the present invention, there is provided a method for coating a housing of a lighting unit. The lighting unit has a lighting housing, the method comprising the steps of mixing a fluorinated ethylene propylene (FEP) copolymer, preferably a perfluoroethylene propylene (FEP) copolymer, with barium sulfate and applying the mixed material to a surface of the lighting housing to form a diffusive coating that is transparent to visible light and UV-A. The mixed material may be provided as a film, a direct extrusion coating, or even heat shrink tubing.

[0014] According to a fourth aspect of the present invention, single lighting unit coatings having lengths of 0.01 to 2.00 meters, and most preferably 0.20 to 1.90 meters, are provided for direct extrusion, applied as a continuous coating during manufacturing, and then separated into lamp lengths for service units. For film and heat shrink tubing applications, the total length of the reel is 10 to 500 meters, and most preferably 50 to 150 meters per reel. Custom cut lengths within the above ranges are also optionally available. [Effects of the Invention]

[0015] The present invention addresses the above-mentioned challenges by providing a coating that enables the production of products that reduce the effects of "spotting," a phenomenon in which scattered light creates bright or dark areas on the LED lamp depending on its location within the lighting unit. The coating provided by the present invention also functions as a shatterproof or glass-shard-retaining coating that meets the requirements of IEC 61549, "Shatterproof Safety Lamps," which requires all glass fluorescent lamps to have a shatterproof coating to ensure a glass-free environment in food processing and related industries.

[0016] The spot-like light is generated by the spacing between the individual LEDs when they are arranged on a substrate or strip. This coating is specifically intended for use with LED light sources, allowing the transmission of ultraviolet (UV) light in the wavelength ranges of 315-400 nm (UV-A), 280-315 nm (UV-B), and 100-280 nm (UV-C). It is also suitable for visible light LEDs in the wavelength range of 400-700 nm. An added benefit of this robust and versatile coating is that it protects the lamp from the intrusion of foreign objects and contaminants, while also preventing the release of internal components or debris into the environment in the event of breakage. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is an orthogonal side view of a first embodiment of a standard uncoated LED lighting lamp. [Figure 2] FIG. 2 is an orthogonal side view of a second embodiment of an LED lighting lamp coated with a polymeric diffusing material of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described with reference to the drawings. It should be noted that the accompanying drawings merely illustrate embodiments of coatings on lighting tubes. Conventional phosphorescent lamps, such as those traditionally referred to as fluorescent lamps, emit light by high-energy excitation of a low-pressure mixture of mercury and rare gases with electrons. Due to the nature of the transition, at least a portion of this light is in the ultraviolet range, which is not only unnecessary for traditional white light applications but also potentially dangerous to users in the vicinity of the lighting fixture. To ensure safe use in domestic and industrial environments and to produce light in the visible wavelength range, lighting fixture tubes are typically coated with one or more materials on the inside or outside of the tube, depending on the nature and function of the coating. These materials absorb ultraviolet light and re-emit visible wavelengths. Furthermore, coatings allow light to radiate in all directions, providing a more diffused light that is more comfortable for users. Similarly, coatings can be applied to lighting units, such as incandescent light bulbs, to diffuse the light emitted from the filament and eliminate residual UV radiation.

[0019] In recent years, with the advent of commercially available LED light sources, a material layer, such as a coating or film, has been used between the LED light source and the user. LEDs emit a narrow wavelength range, and to convert this light into white light, the emitted light is transmitted through a layer of phosphorescent material. This invention provides a coating that transmits ultraviolet light, particularly UV-A, while producing diffused light in the surrounding area. UV light is used, for example, in tanning salons, while UV-B light promotes tanning and helps with the natural production of vitamin D. Applications of UV-transmitting lighting units include, but are not limited to, applications in the pest control industry. UV light attracts insects, which can be captured with appropriate traps or eradicated using traditional UV lights, as used in many food facilities. This provides enhanced protection for food crops. Furthermore, UV light is also used to harden materials (polymerize monomers to form polymers), for example, in inks, adhesives, coatings, and 3D dental materials. UV light can also be used to control the behavior of pets and livestock, such as reptiles and poultry.

[0020] Figures 1 and 2 show a lighting unit with a tube containing multiple LED light sources. While each LED emits light in a very narrow wavelength range, when combined, the LED light source emits light across the entire visible and ultraviolet spectrum, including 315-400 nm (UV-A), 280-315 nm (UV-B), and 100-280 nm (UV-C). The diodes to be installed or driven are selected based on the purpose of the lighting unit. Unlike conventional lighting, the lighting housing is configured to allow UV radiation and transmission. This configuration creates a unique challenge: the diffuse light generated on the outside of the tube requires that the applied coating be UV-resistant and resistant to UV degradation.

[0021] 1 and 2, a generally tubular linear LED lighting housing 10 houses LED lights (generally designated 14 and 15) and houses LED light source elements (LEDs) 11 arranged in a linear configuration on a circuit board 12. This allows power to be supplied to the LEDs 11. Power is supplied to the circuit board 12 via pins 13 and drivers 16 attached to the ends of the tubular portions 14 and 15, which control the illumination of the LEDs 11. The linear LED lighting housing 10 has an enclosed space, preventing air from entering the LEDs 11 and driver 16 and maintaining a low-pressure environment. A coating material 17 is applied to the exterior of the linear LED lighting housing 10, etc., giving the linear LED lighting housing 10 an opaque appearance both when powered and when not powered, compared to the transparent appearance of a standard uncoated lamp. When powered, the light from within the linear LED lamp is diffused, creating a more opaque appearance. In FIG. 1, the linear LED lighting housing 10 is shown as a standard uncoated lamp for reference, while in FIG. 2 the lamp is fully coated over its entire cylindrical exterior and trimmed flush with the end caps removed to expose the contact pins 13.

[0022] A coating specifically contemplated by the present invention is a polymer resin blended with a white particulate solid to promote light diffusion without reducing the coating material's transmittance to visible and ultraviolet light. In its broadest aspect, the present invention contemplates a coating comprising a polymeric material formed from a fluorinated polymer. The polymeric material is preferably selected from fluoropolymer coatings such as polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), including mixtures thereof. Materials such as polycarbonate (PC) and polyethylene terephthalate (PET) are less preferred for UVA-emitting light sources due to potential material degradation, but are suitable for white LED lamps. The most preferred material is tetrafluoroethylene-hexafluoropropylene copolymer (FEP). The fluoropolymer coating preferably has a refractive index of 1.30 to 1.60, such as PVDF (1.443), PCTFE (1.435), ETFE (1.4), FEP (1.344), PFA (1.34), PTFE (1.356), THV (1.35), PC (1.586), PET (1.575), etc.

[0023] This copolymer is mixed with uniformly dispersed light-diffusing particles, such as metal oxide particles such as titanium dioxide, glass beads, or white inorganic powders such as barium sulfate or magnesia. The particulate matter preferably comprises 0.5 to 5.0% by weight of the total mixture. The particle size of the particulate matter is selected depending on the application, but can be in the range of 3 to 30 μm, particularly about 0.7 μm. A preferred particulate matter is barium sulfate (barite and some synthetic grades), which can have a particle size in the range of 3 to 30 μm, particularly about 0.7 μm (precipitated barium sulfate, blanc-fixe). For certain applications, the particle size of the particulate matter is less than 0.02 nm. The amount of barium sulfate is selected depending on the specific application envisioned. The preformed polymer is fed into an extruder, where the extrusion process softens the polymer and mixes it with the barium sulfate to form a suitable coating material.

[0024] The particulate material preferably has a refractive index of 1.00 to 2.30, such as titanium dioxide particles (refractive index 2.65), glass beads (refractive index 1.5 to 2.4), white inorganic powders such as barium sulfate (refractive index 1.64), magnesia (refractive index 1.00 to 111.734 @632 nm), and titania (refractive index 1.55 to 2.3).

[0025] The resulting material can be used in a variety of applications. The blend density of the diffusion coating is controlled by the maximum allowable UV transmittance block, which must not exceed 10% of the UV light source's original output. A transmittance block greater than 10% will not meet the required output level. First, the material can be molded into a tube and used as a light source housing. The thickness of the material ranges from 180 to 500 μm, preferably 200 to 300 μm, with a tolerance of ±30 μm. This tube can be directly extruded into a lamp, or it can be used as a standalone tube with a secondary expansion process to form a heat-shrinkable tube.

[0026] Second, the material can be formed into a film and applied to the surface of the housing. The film thickness also ranges from 180 to 500 μm. When applied as a film or sleeve, it is applied at the end of the process, simplifying the application process, improving the assembly efficiency of the base lamp and reducing rejects and defects (the internal diffusion layer is not damaged when the LED component is inserted into the glass envelope). The external coating prevents the ingress of foreign matter (water, dust, oil, and other contaminants) into the glass envelope, reducing lifespan and premature failure.

[0027] Third, the resulting mixture can be extruded in the molten state to form a tubular or film-like material that can be applied directly to the flat or cylindrical surface of a lighting housing. For applications such as pest control and flying insect control, the optimum thickness for a 2.5% barium sulfate blend is 180-210 microns to maximize UV ​​transmittance while minimizing spotting.

Claims

1. A lighting unit (14, 15) comprising a light source (11) held in a housing (10), the housing has an outer coating (17) comprising a polymeric material; The coating has dispersed therein a particulate material that diffuses light emitted from the light source.

2. 2. The lighting unit according to claim 1, wherein the polymer material is selected from fluoropolymers.

3. 3. The lighting unit of claim 2, wherein the polymer material is selected from polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), and mixtures thereof.

4. 4. A lighting unit according to claim 2 or claim 3, wherein the polymer material is a perfluorinated material.

5. 3. The lighting unit according to claim 2, wherein the polymer material is an ethylene / propylene copolymer.

6. 6. The lighting unit according to claim 5, wherein the polymer material is a tetrafluoroethylene-hexafluoropropylene copolymer.

7. 2. The lighting unit of claim 1, wherein the polymer material is polycarbonate or polyethylene terephthalate.

8. 3. The lighting unit according to claim 2, wherein the coating containing a fluoropolymer has a refractive index of 1.30 to 1.

60.

9. 9. The lighting unit according to claim 1, wherein the particulate material is a metal oxide.

10. 9. The lighting unit according to any one of claims 1 to 8, wherein the particulate material is selected from titanium dioxide, glass beads, or white inorganic powders such as barium sulfate, magnesia, etc.

11. 11. The lighting unit of claim 10, wherein the particulate material is barium sulfate.

12. 12. The lighting unit of claim 11, wherein barium sulfate is present in the coating at 0.5 to 5.0% w / w.

13. 13. The lighting unit according to claim 1, wherein the particulate material has an average particle size of 3.0 μm to 30.0 μm.

14. 14. The lighting unit of claim 13, wherein the particulate material has an average particle size of 0.7 μm.

15. 12. The lighting unit according to claim 1, wherein the particulate material has an average particle size of less than 0.02 nm.

16. 16. The lighting unit according to any one of claims 1 to 15, wherein the particulate material has a refractive index of 1.00 to 2.

30.

17. The lighting unit according to any one of claims 1 to 16, wherein the light source is an LED light source.

18. A lighting unit according to any one of the preceding claims, wherein the coating has a thickness preferably between 180.0 and 500.0 μm.

19. Particulate material barium sulfate (BaSO ４ a polymeric material formed from fluorinated ethylene propylene copolymer (FEP) having dispersed therein A coating for lighting units that is applied to the exterior surface of the housing to diffuse the emitted light and give it an evenly distributed appearance.

20. 20. The coating for a lighting unit of claim 19, wherein the barium sulfate is present in the coating at a concentration of 0.5 to 5.0% w / w.

21. 21. The coating for a lighting unit according to claim 19 or 20, wherein the particle size of the barium sulfate is selected from the range of 3 to 30 μm.

22. 22. The coating for a lighting unit of claim 21, wherein the particulate material has an average particle size of 0.7 μm.

23. 20. The coating for a lighting unit of claim 19, wherein the particulate material has an average particle size of less than 0.02 nm.

24. The coating for a lighting unit according to any one of claims 19 to 23, wherein the coating has a thickness of 180 to 500 µm.

25. 25. The coating for a lighting unit according to claim 24, wherein the coating has a thickness of 200 to 300 μm.

26. 1. A method of coating a housing of a lighting unit having a lighting housing, comprising: mixing a fluorinated ethylene-propylene (FEP) copolymer with barium sulfate; applying the mixed material to a surface of the lighting housing to form a diffusing coating that is transparent to visible light and UV-A. A method for coating a housing of a lighting unit comprising:

27. 27. The method for coating a lighting unit according to claim 26, wherein the copolymer is a perfluoroethylene-propylene (FEP) copolymer.

28. 27. The method of coating a lighting unit according to claim 26, or the method of coating a lighting unit according to claim 1, wherein the mixed material is provided as a film.

29. 27. The method of coating a lighting unit according to claim 26, or the method of coating a lighting unit according to claim 1, wherein the mixed material is provided as a direct extrusion coating.

30. 27. The method of coating a lighting unit according to claim 26, or the method of coating a lighting unit according to claim 1, wherein the mixed material is provided as a heat shrink tube.

31. It is applied as a continuous coating during manufacturing and separated into lamp lengths for service units. Single lighting unit coatings available in lengths from 0.01 to 2.00 meters for direct extrusion.

32. 32. The single lighting unit coating of claim 31, having a length of 0.20 to 1.90 meters.

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