Diffusion coating for lighting devices
By using diffuse coatings of fluoropolymers and barium sulfate particulate materials in LED lighting devices, the problems of spots and glare in LED lighting devices are solved, and transmission and UV resistance to specific UV wavelengths are achieved.
Patent Information
- Application Number
- CN202380070255.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-09-29
- Filing Date
- 2023-09-26
- Publication Date
- 2025-05-23
AI Technical Summary
The prior art is difficult to effectively reduce spots and glare generated by a single LED in LED lighting devices, while also requiring material degradation that prevents UV radiation and resists UV light.
Fluoropolymer material is used as the coating, combined with barium sulfate particulate material, to form a coating with a diffusive effect, allowing UV and visible light to be transmitted at a specific wavelength and preventing foreign matter and debris from entering.
The effect of reducing spots and glare in LED lighting devices is achieved, while providing transmission capabilities to UV-A, UV-B and UV-C wavelengths, enhancing the UV resistance and anti-shatter properties of the coating.
Smart Images
Figure CN120035778A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to coatings for light emitting diode (LED) lighting tubes and the like to diffuse and reduce the speckle and glare produced by the individual LEDs within the device. When placed on a board or strip, the speckle is caused by the spacing between the individual LEDs. The coating is particularly intended for use with LED light sources and allows the transmission of radiation in the ultraviolet (UV) range of 315nm to 400nm (UV-A), 280nm to 315nm (UV-B) and 100nm to 280nm (UV-C) wavelengths, and is also suitable for visible light LEDs of 400nm to 700nm wavelengths. Other benefits of this durable and versatile coating are that it prevents foreign matter or contaminants from entering the tube, while also preventing all internal components or fragments of these components from entering the environment in the event of accidental breakage. Background Art
[0002] In the manufacture of conventional incandescent or fluorescent lighting fixtures, the lighting fixture has a transparent housing surrounding a light source in the form of a bulb, tube, etc. that produces light radiation. Coatings are typically applied to one or both of the inner or outer surfaces of the housing. Coatings are used to reduce glare and provide more uniform light to the surroundings, as well as to protect people near the light from UV radiation emitted by the light source. Depending on the housing material, there are a variety of materials that can be used as coatings.
[0003] For example, in the case of a glass housing, one method of forming a coating on the outside of the tube is to dissolve an acrylic monomer or resin in an organic solvent, optionally with transparent silicone particles suspended therein. The solvent is then removed and the necessary polymerization reaction is carried out to form the coating. The disadvantage of using this method is that many of the most suitable solvents are toxic and equipment is required to safely remove and capture the removed solvent. Alternatively, a water-based system can be used, but this generally requires a higher energy cost to remove the water compared to organic solvents and generally also requires polymerization of the monomers to form the coating.
[0004] In a similar solution to the above problem, a preformed tube or film material is secured around the housing. A material such as polyethylene terephthalate (PET) can be slid onto the glass housing as a preformed tube, or wrapped around the housing. This material can be incorporated with particulate material to help diffuse the light toward the user. One disadvantage of this coating is that the PET material is susceptible to degradation by heat or UV light. In this case, the transmission of the coating can be reduced, and the coating can become brittle and peel off, leading to environmental pollution and malfunctioning lamps.
[0005] Prior art coatings are also typically designed to filter out any radiation that emits UV wavelengths, as this can be harmful to people near the lighting fixture. This is typically achieved by converting ultraviolet (UV) radiation into radiation in the visible range (400nm to 700nm) by fluorescence or phosphorescence. Even in cases where a coating does allow UV light to be transmitted, it is difficult to produce a coating that allows transmission of a specific wavelength or set of wavelengths (UV-A transmission is reduced by up to 60%), or to control the thickness of the applied coating.
[0006] The present invention aims to provide a coating that solves the above problems and enables the production of products that reduce the "spot" effect, i.e., scattering that causes lighter or darker areas on the lamp tube depending on the position of the LED lamp in the lighting fixture. The coating provided herein also acts as an anti-shatter coating or glass shard containment coating, complying with the requirements of IEC 61549 shatterproof safety lamps, which is applicable to food processing and related industries and aims to ensure a glass-free environment and stipulates that all glass fluorescent lamps must be coated with an anti-shatter coating. Summary of the invention
[0007] According to a first aspect of the present invention, there is provided a lighting device, comprising a light source housed in a housing, the housing having an outer coating comprising a polymer material, the coating having a particulate material distributed therein for diffusing the light emitted by the light source. The coating functions to diffuse and / or prevent the transmission of light of a predetermined wavelength, and helps to contain debris and prevent the entry of water, insects and other substances harmful to the lighting device. For example, the coating can be selected to allow transmission of UV between wavelengths of 315nm to 400nm (UV-A), 280nm to 315nm (UV-B) and 100nm to 280nm (UV-C), and visible light of 400nm to 700nm, and the coating can diffuse the light radiation to make the light distribution in the peripheral area of the lighting device more uniform.
[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), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), etc. and mixtures thereof. Perfluorinated materials are preferred materials. Due to material degradation, materials such as polycarbonate (PC) and polyethylene terephthalate (PET) are less preferred choices on UVA emitting light sources, but they are feasible for white light LED lamps. The polymer is preferably an ethylene / propylene copolymer, particularly a perfluorinated ethylene / propylene copolymer, for example, the most preferred material is a tetrafluoroethylene-hexafluoropropylene copolymer.
[0009] The refractive index of the fluoropolymer coating is preferably between 1.30 and 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, magnesium oxide or mixtures thereof). The particulate material is preferably barium sulfate, and is further preferably present in an amount of 0.5% w / w to 5.0% w / w of the coating. The average particle size of the particulate material is preferably 3.0 μm to 30.0 μm, especially 0.7 μm. In an alternative embodiment, the average particle size of the particulate material is <0.02 nm.
[0011] The refractive index of the granular material is preferably 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), magnesium oxide (refractive index 1.00 to 111..734@632.nm), titanium dioxide (refractive index 1.55 to 2.3).
[0012] The light source is preferably an LED light source to provide energy efficiency and durability.
[0013] The thickness of the coating layer is preferably 180.0 μm to 500.0 μm.
[0014] According to a second aspect of the present invention, there is provided a coating for a lighting device, the coating comprising a fluorinated ethylene-propylene copolymer (FEP) having barium sulfate (BaSO 4 ) of a polymer material, which is located on the outer surface of the shell to diffuse the emitted light into a uniformly distributed visual appearance.
[0015] The barium sulfate is preferably present in the coating in an amount of 0.5% w / w to 5.0% w / w. The average particle size of the barium sulfate is preferably 3 μm to 30 μm, more preferably 0.7 μm. In an alternative embodiment, the average particle size of the barium sulfate is <0.02 nm. The thickness of the coating is preferably 180 μm to 500 μm, more preferably 200 μm to 300 μm.
[0016] According to a third aspect of the present invention, there is provided a method for coating a housing of a lighting device, the lighting device having a lamp housing, the method comprising the steps of blending a fluorinated ethylene-propylene (FEP) copolymer (preferably a perfluorinated ethylene-propylene (FEP) copolymer) with barium sulfate, and applying the blended material to the surface of the lamp housing to provide a diffuse coating transparent to visible light and UV-A. The blended material is optionally provided in film form.
[0017] Alternatively, the blended material is also optionally provided in the form of a direct extrusion coating.
[0018] Alternatively, the blended material is also provided in the form of heat shrink tubing.
[0019] According to a fourth aspect of the present invention, there is provided a coating for a single lighting device, the coating for the single lighting device is provided as a length of 0.01 m to 2.00 m, preferably 0.20 m to 1.90 m for direct extrusion, applied as a continuous coating during the manufacturing process, and then divided into lamp lengths for application units. For films and heat shrink tubing, the total length of the roll is 10 m to 500 m, and each roll is most preferably 50 to 150 m. Customized cut lengths within the above ranges can also be optionally provided. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The invention will now be described with reference to the accompanying drawings, which show, by way of example only, embodiments of the coating on a lighting tube. In the drawings:
[0021] Figure 1 An orthogonal side view of the first embodiment showing an uncoated LED lighting lamp as a standard; and
[0022] Figure 2 An orthogonal side view of a second embodiment of an LED lighting lamp coated with the polymer diffuser material of the present invention is shown. DETAILED DESCRIPTION
[0023] In conventional photoluminescent light sources, commonly referred to as fluorescent lamps, a low-pressure gas mixture of mercury and rare gases generates light energy through the excitation of electrons. Due to the nature of these transitions, at least part of the light is in the UV range - which is not only irrelevant to conventional white light illumination needs, but can also be potentially harmful to users near the light source. To ensure that such light sources are safe for use in domestic and industrial environments and produce light in the visible wavelength range, one or more layers of material are usually coated on the inner or outer wall of the lamp tube - the specific application location depends on the nature of the coating and its optical function. The material absorbs the UV light and re-emits light at visible wavelengths. In addition, the coating acts to emit light in all directions, thereby providing a more comfortable diffuse light for the user.
[0024] Similarly, coatings can be applied to lighting devices, such as bulbs with incandescent elements, to diffuse the light produced by the filament and remove any residual UV light. Recently, the rise of commercial LED light sources has also utilized a material layer, such as a coating or film of material, between the LED light source and the user. LEDs emit a narrow range of wavelengths, and in order to convert them into white light, the emitted light passes through a layer of photoluminescent material. The present invention provides a coating that produces diffuse light to the surrounding environment, but allows the transmission of UV radiation, most preferably UV-A radiation. UV radiation is used, for example, in tanning beds, where UV-B can make people tan and naturally produce vitamin D. As a further non-limiting example of the use of UV transmissive lighting devices, it can be used in the pest or insect control industry. UV light acts to attract insects, which can then be captured or destroyed in a suitable trap, such as in conventional UV light found in most food institutions. This can provide better protection for food crops. In addition, UV light is used to cure materials (monomers are polymerized to form polymers), such as for inks, adhesives, coatings, and 3-D materials such as those formed in dentistry. The behavior of pets and livestock, such as reptiles and poultry, can also be controlled through the use of UV light.
[0025] refer to Figure 1 and Figure 2 , these figures show a lighting device including a tube housing a plurality of LED light sources which, in combination, emit light across the visible and UV spectrum, including 315nm to 400nm (UV-A), 280nm to 315nm (UV-B) and 100nm to 280nm (UV-C) - each LED emitting light of a very narrow wavelength. In use, existing or activated diodes will be selected according to the purpose of the lighting device. Unlike conventional lamps, the lamp housing is configured to allow emission and transmission of UV light. This poses a special problem because in order to produce diffuse light on the outside of the lamp tube, the applied coating needs to be more resistant to UV radiation and able to resist material degradation caused by UV radiation.
[0026] exist Figure 1 and Figure 2 In the embodiment, a generally tubular, linear LED lamp housing 10 is provided with LED light sources (generally labeled 14, 15) inside. LED light source elements (or LEDs) 11 are mounted in a linear array on a circuit board 12 to supply power to the LEDs 11. Power is supplied to the circuit board 12 through pins 13 at the ends of the tubes 14 and 15 and a driver 16, which controls the illumination of the LEDs 11. The linear LED lamp housing 10 provides a sealed space that prevents air from entering the LEDs 11 and the driver 16, thereby maintaining a low-pressure environment.
[0027] The coating material 17 is applied to the outer surface or the like of the linear LED lamp housing 10, which gives the linear LED lamp housing 10 an opaque visual appearance, which is more noticeable in the powered mode because light from within the linear LED lamp is thereby diffused, compared to the transparent visual appearance of a standard uncoated lamp in both the powered and powered off modes. Figure 1 In the example, the linear LED lamp housing 10 is shown as a standard uncoated lamp for reference, while in Figure 2 In FIG. 1 , the lamp is shown as being completely coated over the entire cylindrical outer surface, with only the end being trimmed flush with the end cap so that the pin 13 is exposed.
[0028] The coatings particularly involved in the present invention are polymer resins blended with white particulate solids to help diffuse light without reducing the transmittance of the coating material to visible light and UV light. In the broadest sense, the present invention comprises a coating of a polymer material formed by a fluorinated polymer. The polymer material is preferably selected from a fluoropolymer coating, such as polyvinylidene fluoride (PVDF), polytrifluorochloroethylene (PCTFE), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), etc. and mixtures thereof. Due to material degradation, materials such as polycarbonate (PC) and polyethylene terephthalate (PET) are less preferred choices on UVA emitting light sources, but they are feasible for white light LED lamps. The most preferred material is tetrafluoroethylene-hexafluoropropylene copolymer (FEP).
[0029] The refractive index of the fluoropolymer coating is preferably between 1.30 and 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).
[0030] The copolymer is blended with uniformly distributed light diffusing particles such as metal oxide particles (such as titanium dioxide), glass beads, white inorganic powders (such as barium sulfate, magnesium oxide). The particulate material is preferably present in 0.5% to 5.0% by weight of the total mixture. The particle size of the particulate material is selected according to the application, which can be 3μm to 30μm, especially about 0.7μm. The preferred particulate material is barium sulfate (barytes and some synthetic grades), which has a particle size of 3μm to 30μm, especially about 0.7μm (precipitated barium sulfate (blanc-fixe)). For some uses, the particle size of the particulate material is <0.02nm. The amount of barium sulfate is selected to suit a specific application. The preformed polymer is fed into an extruder, and the polymer is softened by the extrusion process and blended with the barium sulfate to form a suitable coating material.
[0031] The refractive index of the granular material is preferably 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), magnesium oxide (refractive index 1.00 to 111..734@632.nm), titanium dioxide (refractive index 1.55 to 2.3).
[0032] The resulting material can be used in a variety of ways. The mixing density of the diffuse coating is controlled by the maximum allowable UV transmittance block, which will not exceed ≥10% of the original output of the UV light source. When the transmittance blockage is >10%, the system will not be able to achieve the desired output level. First, the material can be formed into a tube used as a light source housing. The thickness of the material can be 180μm to 500μm, preferably 200μm to 300μm, with a tolerance of + / -30μm. The tube can be extruded directly onto the lamp, or it can be used as a separate tube (in which case it needs to be processed into a heat shrink tube through a secondary expansion process).
[0033] Second, the material can be formed into a film applied to the surface of the housing, with a thickness of 180 μm to 500 μm. Using a film or sleeve can simplify the process flow because it is applied at the end of the process, which allows for more efficient assembly of the base lamp with less scrap or defects (no scratches on the internal diffuser layer when the LED component is inserted into the glass envelope). The external coating helps prevent foreign matter (contaminants such as water, dust and grease) from entering the glass housing, thereby avoiding the resulting short service life / early failure.
[0034] Third, the resulting mixture can be extruded as a melt to form a tube or film of material for direct application to a flat or tubular cylindrical surface of a lamp housing. For materials containing a mixture of 2.5% barium sulfate (e.g. for pest / fly control), the optimum material thickness is 180 μm to 210 μm (micrometers) to maximize UV transmission while effectively reducing "spots".
Claims
1. A lighting device (14, 15) comprising a light source (11) housed within a housing (10), the housing having an outer coating (17) comprising a polymeric material, the coating having particulate material distributed therein for diffusing light emitted by the light source.
2. The lighting device according to claim 1, wherein the polymeric material is selected from fluoropolymers.
3. The lighting device according to claim 2, wherein the polymeric material is selected from polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), and mixtures thereof.
4. The lighting device according to claim 2 or 3, wherein the polymeric material is a perfluoropolymer material.
5. The lighting device according to claim 2, wherein the polymeric material is an ethylene / propylene copolymer.
6. The lighting device according to claim 5, wherein the polymeric material is a tetrafluoroethylene-hexafluoropropylene copolymer.
7. The lighting device according to claim 1, wherein the polymeric material is polycarbonate or polyethylene terephthalate.
8. The lighting device according to claim 2, wherein the refractive index of the fluoropolymer coating is from 1.30 to 1.
60.
9. The lighting device according to any one of the preceding claims, wherein the particulate material is a metal oxide.
10. The lighting device according to claims 1 to 8, wherein the particulate material is selected from titanium dioxide, glass beads, or white inorganic powders such as barium sulfate, magnesium oxide.
11. The lighting device according to claim 10, wherein the particulate material is barium sulfate.
12. The lighting device according to claim 11, wherein the barium sulfate is present in the coating at 0.5 wt / wt% to 5.0 wt / wt% of the coating.
13. The lighting device according to any one of the preceding claims, wherein the average particle size of the particulate material is from 3.0 μm to 30.0 μm.
14. The lighting device according to claim 13, wherein the average particle size of the particulate material is 0.7 μm.
15. The lighting device according to claims 1 to 11, wherein the average particle size of the particulate material < 0.02 nm.
16. The lighting device according to any one of the preceding claims, wherein the refractive index is from 1.00 to 2.
30.
17. The lighting device according to any one of the preceding claims, wherein the light source is an LED light source.
18. The lighting device according to any one of the preceding claims, wherein the thickness of the coating is preferably from 180.0 μm to 500.0 μm.
19. A coating for a lighting device, the coating comprising a fluorinated ethylene-propylene copolymer (FEP) having barium sulfate (BaSO 4 ) of a polymer material, which is located on the outer surface of the shell to diffuse the emitted light into a uniformly distributed visual appearance.
20. The coating for a lighting device according to claim 19, wherein the barium sulfate is present in the coating in an amount of 0.5 wt / wt% to 5.0 wt / wt%.
21. The coating for a lighting device according to claim 19 or 20, wherein the particle size of the barium sulfate is selected from 3 μm to 30 μm.
22. The coating for a lighting device according to claim 21, wherein the average particle size of the particulate material is 0.7 μm.
23. The coating for a lighting device according to claim 19, wherein the average particle size of the particulate material is <0.02 nm.
24. The coating for a lighting device according to claims 19 to 23, wherein the coating has a thickness of 180 μm to 500 μm. 25 . The coating for a lighting device according to claim 24 , wherein the coating has a thickness of 200 μm to 300 μm.
26. A method for coating a housing of a lighting device, the lighting device having a lamp housing, the method The following steps are involved: A fluorinated ethylene-propylene (FEP) copolymer is blended with barium sulfate and the blended material is applied to the surface of the lamp housing to provide a diffuse coating that is transparent to visible light and UV-A.
27. The method of coating a lighting device according to claim 26, wherein the copolymer is a perfluoroethylene-propylene (FEP) copolymer.
28. A method of coating a lighting device according to claim 26 or 27, wherein the blended material is provided in the form of a film.
29. A method of coating a lighting device according to claim 26 or 27, wherein the blended material is provided in the form of a direct extrusion coating.
30. The method of coating a lighting device according to claim 26 or 27, wherein the blended material is provided in the form of a heat shrink tubing.
31. A coating for a single lighting device provided in lengths of 0.01 to 2.00 meters for direct extrusion, applied as a continuous coating during the manufacturing process and then divided into lamp lengths for application units.
32. The coating of a single lighting device according to claim 31, wherein the length of the coating is 0.20 meters to 1.90 meters.