Filament-based solid-state lighting devices

Abstract

A lighting device 1 is disclosed, comprising a transparent housing 3 and a filament 10 within the transparent housing. The filament comprises a transparent substrate 20 supporting a plurality of solid state lighting elements 30, and a phosphor-containing resin coating 40 surrounding the filament. The resin coating includes at least one region 42 through which light generated by the solid state lighting elements that is not converted by the phosphor escapes, and the transparent housing supports, for each of said regions of the resin coating, a further phosphor layer 7 covering a portion of the transparent housing, each further phosphor layer being arranged to receive the unconverted light that escapes from at least one of said regions. Also disclosed is a method of manufacturing such a lighting device.

Description

Technical Field

[0001] The present invention relates to a lighting device including a transmissive housing, a filament within the transmissive housing, the filament including a transmissive substrate supporting a plurality of solid-state lighting elements, and a phosphor-containing resin coating surrounding the filament.

[0002] The present invention further relates to a method of manufacturing such a lighting device.

Background Art

[0003] Solid-state lighting devices, such as lighting devices based on light emitting diodes (LEDs), are rapidly replacing other forms of lighting devices, such as incandescent lighting devices, halogen lighting devices, fluorescent lighting devices, etc., due to the excellent lifespan, robustness, and energy efficiency of the solid-state lighting devices. Despite the clear advantages of solid-state lighting devices over other types of lighting devices, several challenges still need to be overcome for solid-state lighting devices to be widely accepted as replacements for such other types of lighting devices.

[0004] For example, it is not easy to manufacture a solid-state lighting device that emulates the appearance and light output of a conventional lighting device, such as a filament-based lighting device. For this purpose, solid-state lighting devices have been manufactured in which a plurality of solid-state lighting elements, such as LEDs, are mounted on an elongated support that mimics a filament. For example, International Publication No. 2020 / 069723 (A1) discloses a linear LED light source comprising a plurality of LED units electrically connected to a metallic support frame, the metallic support frame being configured to function as a supply conductor through which power for driving the LED units can be supplied to the LED units.

[0005] Such filament assemblies may be coated with a phosphor-containing resin coating, thereby allowing light generated by an LED, such as blue light, to be spectrally converted by phosphor particles in the resin to produce, for example, white light. As is well known, the color temperature of the white light thus produced may be controlled by the composition and amount of phosphor in the resin. In such filament assemblies, the elongated support is typically made of a light-transmitting material so that light can pass through the filament from substantially every part of the resin surface, thereby emulating the complete 360° emission distribution of conventional filament-based incandescent lighting devices. However, even when such an emission distribution can be successfully emulated to a considerable extent, achieving uniformity in the spectral composition of the light emitted from the resin surface surrounding the elongated support that supports the solid lighting element remains challenging. Such differences can be very noticeable, for example, when light is projected onto a surface or onto a moving observer, and the observer receives emission outputs from different areas of the resin surface as they move relative to the lighting device. In particular, when such light output is projected onto a surface such as a work surface, the spectral variations of the projected light output can be quite bothersome to people who need appropriate lighting to perform a specific task.

[0006] One specific solution to this problem would be to provide a diffusive coating on the light-transmitting housing of the filament assembly. For example, U.S. Patent Application Publication 2018 / 0299080(A1) discloses an LED lamp comprising a substrate, an LED light source optically communicating with the housing of the LED lamp, a diffusive coating applied to the housing, and a luminescent coating at least partially disposed on the diffusive coating. The luminescent coating is located between the LED light source and the diffusive coating. The luminescent coating has a composition selected to achieve a specific color temperature according to the characteristics of the LED light source. However, such a solution significantly reduces the luminous efficiency of the lighting device, resulting in a loss of luminescent power. This is undesirable, for example, from the standpoint of achieving compliance with energy efficiency regulations, which typically require that a minimum amount of lumens per watt be generated. For example, in order for a (tubular) lighting device to achieve Class A certification in the European Union, it needs to achieve a light output of 210 lm / W or more, which is difficult to achieve, especially when light loss occurs in the translucent housing due to the presence of, for example, a diffusion layer. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention seeks to provide a lighting device that addresses at least some of the aforementioned problems, comprising a transparent housing and a filament within the transparent housing having a transparent substrate supporting a plurality of solid lighting elements.

[0008] The present invention further seeks to provide a method for manufacturing such lighting devices. [Means for solving the problem]

[0009] According to an embodiment of one aspect of the present invention, a lighting device is provided, comprising a transparent housing, a filament within the transparent housing including a transparent substrate supporting a plurality of solid-state lighting elements, and a phosphor-containing resin coating surrounding the filament, the resin coating including at least one region having a reduced thickness that allows light generated by the solid-state lighting elements, which has not been converted by the phosphor, to leak out, wherein the transparent housing supports a further phosphor layer covering a portion of the transparent housing, which is optically aligned with each of the regions of the reduced-thickness resin coating, and each of the further phosphor layers is arranged to receive unconverted light leaking from at least one of the aforementioned regions. The present invention is based on the insight that variations in the spectral composition of the luminescence output of a filament having solid-state lighting elements are caused by variations in the thickness of the phosphor-containing resin coating surrounding a transparent substrate supporting the solid-state lighting elements, such as LEDs. Therefore, by providing an additional phosphor layer on the housing for each region of the phosphor-containing resin coating with reduced thickness, and by optically aligning such additional phosphors with such regions of the phosphor-containing resin coating with reduced thickness, the spectral uniformity of the light output of the lighting device can be improved. At the same time, the remaining portion of the filament housing remains transparent, and light loss caused by a diffusion layer is avoided because there is no such diffusion layer covering the entire surface of the housing, thus improving the luminous efficiency of the lighting device.

[0010] For example, the transparent substrate may include a mounting surface supporting at least some of the solid-state lighting elements, and a pair of sides on either side of the mounting surface, each of which is covered by one of the aforementioned regions of the resin coating. The phosphor-containing resin coating may have a reduced thickness on the sides of the transparent substrate, so that the light emitted through the regions of the phosphor-containing resin coating on these sides has a different spectral composition from the light emitted through other regions of the phosphor-containing resin coating, for example, the region covering the mounting surface of the transparent substrate, and this difference in spectral composition is compensated for by an additional phosphor layer on the housing, as described above.

[0011] The transparent substrate may include a single mounting surface, i.e., the solid-state lighting element may be mounted on only one surface of the transparent surface. In such a scenario, the solid-state lighting element may be dual-emitting, configured to emit light both toward and away from the transparent substrate. This has the advantage of achieving an emission distribution that closely emulates a complete 360° emission distribution, while allowing for relatively simple thermal management of the filament. Alternatively, the transparent substrate may further include additional mounting surfaces opposite to the aforementioned mounting surface, with the sides extending between the mounting surface and the additional mounting surface, and the solid-state lighting element may be distributed across the mounting surface and the additional mounting surface.

[0012] The permeable substrate may be made of any suitable material. In certain embodiments, the permeable substrate is a sapphire substrate, but alternative materials such as permeable ceramic materials or flexible polymer materials such as polyimide are also feasible.

[0013] Each of the additional phosphor layers is preferably located on the inner surface of the transparent housing to protect it from accidental damage, such as scratching. Alternatively, each of the additional phosphor layers may be located on the outer surface of the transparent housing, which has the advantage that the additional phosphor layers can be applied to the housing in a particularly simple manner.

[0014] The transparent housing may be made of any suitable transparent material. For example, the transparent housing may be a transparent housing made of glass or plastic. In a particular series of embodiments, the transparent housing is molded as a tubular body, and for example, the lighting device may be a tubular LED (TLED) device that produces a light output of at least 210 lm / W. In this particular series of embodiments, the transparent housing may include a pair of further phosphor layers, each extending along the tubular body and having a radial width in the range of 60 to 90°, so that 50 to 67% of the surface of the transparent housing remains uncovered by the further phosphor layers, which ensures that the lighting device can achieve excellent light output efficiency.

[0015] The lighting device may comprise a pair of electrode rails, each electrode rail being electrically connected to the other by a corresponding support arm extending between one of the electrode rails and the filament. This allows the filaments to be connected in parallel, which limits the resistance along the filament chain and thus ensures that the filaments can be driven by a sufficiently compact driver that can be mounted inside the lighting device, for example, inside the end cap of the lighting device.

[0016] If the tubular body is made of plastic, the plastic body may include a pair of channels within its inner surface, each of which extends along the tubular body and accommodates one of the electrode rails. This ensures that the filament assembly is securely mounted within the tubular body, thereby providing a particularly robust lighting device.

[0017] Alternatively, the filament may extend along the tubular body, that is, substantially along the entire length of the tubular body, in which case the lighting device may further include a driver at the first end of the tubular body, the driver having a first connection to a first terminal portion of the filament adjacent to the first end for electrically connecting the filament to the driver, and a second connection to a second terminal portion of the filament adjacent to a second end of the tubular body opposite to the first end. In this case, the lighting device may further include a support structure extending from the second terminal portion of the filament to the second end of the tubular body for fixing the filament within the tubular body.

[0018] According to an embodiment of another aspect of the present invention, a method for manufacturing a lighting device is provided, comprising the steps of: preparing a transparent substrate; mounting a plurality of solid-state lighting elements on the transparent substrate to create a filament; surrounding the filament with a phosphor-containing resin coating, wherein the resin coating includes at least one region having a reduced thickness that allows light generated by the solid-state lighting elements, which has not been converted by the phosphor, to leak out; preparing a transparent housing for the filament; forming a further phosphor layer on a portion of the transparent housing over each of the regions of the resin coating having the reduced thickness; and mounting the filament within the transparent housing by optically aligning each of the regions of the resin coating having the reduced thickness with one of the further phosphor layers, wherein each of the further phosphor layers is positioned to receive unconverted light leaking from the region of the resin coating aligned with the further phosphor layer. Lighting devices manufactured in this manner benefit from improved luminous efficiency due to the use of a translucent housing, and the presence of one or more additional phosphor layers on the translucent housing to convert light generated by the solid lighting element that is not converted by the phosphor-containing resin layer surrounding the filament reduces the variability in the spectral output of the light-emitting device.

[0019] Preferably, the transparent housing is formed as a tubular body, each of which further phosphor layers extends along the tubular body, and the method further includes forming a filament assembly by mounting a plurality of filaments to a pair of electrode rails such that corresponding regions of each filament that leak out light generated by a solid lighting element and not converted by the phosphor are aligned with each other, wherein each filament is electrically connected to each electrode rail by a corresponding support arm extending between one of the electrode rails and the filament, and the step of mounting the filaments in the transparent housing includes mounting the filament assembly in the tubular body such that the electrode rails extend along the tubular body. This has the advantage that each filament can be driven in parallel, thereby making it easier to achieve a desired light emission output, such as a uniform light emission output, along the tubular housing, and fixing the electrode rails in or to the tubular housing further provides a particularly robust filament assembly in the tubular body.

[0020] Alternatively, the transparent housing is formed as a tubular body, each of which further phosphor layers extends along the tubular body, and the method further includes the steps of forming a first connection between a driver and a first terminal portion of the filament, and forming a second connection between a driver and a second terminal portion of the filament opposite to the first terminal portion, and the step of mounting the filament in the transparent housing includes mounting the filament such that the driver is located at the first end of the tubular body and the second terminal portion of the filament is located close to the second end of the tubular body opposite to the first end, and the method further includes the step of mounting a support structure between the second terminal portion of the filament and the second end of the tubular body. In this way, a robust assembly of a single elongated filament can be achieved within the tubular housing.

[0021] These and other aspects of the present invention will become apparent from the embodiments described hereinafter and will be elucidated with reference to those embodiments.

Brief Description of the Drawings

[0022] For a better understanding of the present invention and to more clearly show how the present invention can be carried out, reference will now be made, by way of example only, to the accompanying drawings. [Figure 1] A cross-sectional view of a resin-coated filament is schematically shown. [Figure 2] A cross-sectional view of a lighting device according to one embodiment is schematically shown. [Figure 3] A perspective view of a lighting device according to another embodiment is schematically shown. [Figure 4] A cross-sectional view of the lighting device of FIG. 3 is schematically shown. [Figure 5] A perspective view of the lighting device of FIG. 3 is schematically shown. [Figure 6] A cross-sectional view of a lighting device according to at least some embodiments is schematically shown. [Figure 7] A perspective view of the lighting device of FIG. 6 is schematically shown. [Figure 8] A cross-sectional view of a design aspect of a lighting device according to at least some embodiments is schematically shown. [Figure 9] A cross-sectional view of a lighting device according to at least some alternative embodiments is schematically shown. [Figure 10] An exploded view of a lighting device according to at least some embodiments is schematically shown. [Figure 11] A cross-sectional view of a lighting device according to yet another embodiment is schematically shown. [Figure 12] A flowchart of an exemplary assembly method of an exemplary lighting device.

Modes for Carrying Out the Invention

[0023] The present invention will be described with reference to the drawings.

[0024] The detailed descriptions and specific examples illustrate exemplary embodiments of the apparatus, system, and method, but should be understood to be for illustrative purposes only and not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, system, and method of the invention will be better understood from the following description, the appended claims, and the appended drawings. Please understand that these figures are schematic and not drawn to the correct scale. Also, please understand that the same reference numerals are used throughout these figures to indicate the same or similar parts.

[0025] Figure 1 schematically shows one embodiment of a filament 10 that may be used in various embodiments of the lighting device of the present invention. The filament 10 comprises a transparent substrate 20 for supporting one or more solid-state lighting elements 30. The transparent substrate 20 may be, for example, a transparent sapphire substrate or a transparent ceramic substrate if a relatively rigid filament 10 is required, or a polymer substrate such as a polyimide substrate if the filament 10 is required to be more flexible. The solid-state lighting element 30 may take any suitable shape or form, and may be, for example, one or more LEDs such as blue light-emitting LEDs. The solid-state lighting element 30 may be mounted on a single main surface 22 of the transparent substrate 20, in which case the solid-state lighting element 30 preferably emits light from at least two emission surfaces, for example toward the mounting surface 22 of the transparent substrate 20 and toward away from this surface, in order to provide a filament 10 that exhibits an emission distribution that emulates the emission distribution of an incandescent light bulb filament. Alternatively, a further main surface 26 of the transmissive substrate 20, opposite to the main surface 22, may also support one or more solid-state lighting elements 30 (not shown) to achieve a desired emission distribution of the filament 10. In this case, the solid-state lighting elements 30 may emit light from only a single surface, for example, in a direction away from the surface on which they are mounted.

[0026] The transparent support 20 supporting the solid-state lighting element 30 is typically enclosed within a resin 40 containing a phosphor, for example, in the form of suspended particles in the resin, which converts the light emitted by the solid-state lighting element 30 into light having different spectral compositions. For example, the phosphor may convert the light emitted by the solid-state lighting element 30 into white light having a specific color temperature, which may be controlled by the chemical composition of the phosphor. Any suitable phosphor may be used for this purpose. For example, one or more phosphors that convert blue light into yellow / green light, e.g., YAGaG:Ce, LuAGaG:Ce, or A3B5O 12 Garnets such as :Ce (wherein A represents a chemical element such as Y, Lu, or La, and B represents a chemical element such as Al, Ga, or Fe), and phosphors that convert blue light to orange / red light, such as aluminonitride silicates, or calsin phosphors such as CaAlSiN3:Eu phosphors, or nitride silicates may be used for this purpose. However, it should be understood that the present invention is not limited to these exemplary phosphors, and phosphors having any suitable composition may be used. The resin may be any suitable permeable resin, preferably a transparent resin. Examples of suitable resins include ethyl and phenyl type silicones. Other suitable resins will be immediately apparent to those skilled in the art.

[0027] A problem associated with surrounding the transparent substrate 20 with a resin coating 40 is that the thickness of the resin coating 40 around the transparent substrate 20 is not uniform. As shown in Figure 1, the resin coating 40 typically has thicknesses r1 and r2 on the main surface 22 and the main surface 26, respectively, while the resin coating 40 has a significantly smaller thickness r3 on the side surface 24 of the transparent substrate 20, which extends between the opposite main surface 22 and the main surface 26. This reduced thickness r3, which is typically a function of the thickness d of the transparent substrate 20, stems from the fact that when coating the transparent substrate 20 supporting the solid-state lighting element 30, it is difficult to achieve the same thickness of resin coating 40 on the side surface 24 compared to the main surface 22 and 26. As a result, the light emitted by the solid-state lighting element 30, traveling through the transparent substrate 20 and exiting the substrate through the side surface 24, typically exits the filament 10 through a window 42 defined by a dashed line extending from the side surface 24. Because this light passes through a relatively thin layer of resin coating 40, there is not enough phosphor in the optical path of the light rays passing through this part of the resin coating 40. Therefore, at least a portion of the light rays that thus exit the filament 10 are not converted, and thus retain their original spectral composition as they were when generated by the solid-state lighting element 30. Consequently, this can cause spatial variations in the spectral composition of the luminescence output generated by the filament 10.

[0028] Such spatial variations may be compensated for by diffusing the light output, for example, by mounting the filament 10 in a diffusion housing. However, this causes light loss and therefore impairs the optical efficiency of the lighting device including the filament 10. On the other hand, when a transmissive housing is used with the filament 10, the optical efficiency of the lighting device is improved at the cost of producing a light output with spatial variations in spectral composition. According to the teachings of the present invention, a lighting device 1 is provided, such as the lighting device 1 schematically shown in Figure 2, in which case the housing 3 is made of an optically transparent material such as glass or an optically transparent polymer, and the housing 3 supports an additional phosphor layer 7 on one of its surfaces, i.e., on the inner surface or the outer surface of the housing 3, and the additional phosphor layer 7 is optically aligned with the emission window 42, so that unconverted light escaping from the filament 10 mounted in the fixture or end cap 5 of the lighting device 1 is converted by the additional phosphor layer 7, improving the uniformity of the spectral composition of the light emitted from the lighting device 1 and also improving the perceived light efficiency of the lighting device 1, because the human eye is less sensitive to blue light, for example, light with a wavelength of 400-450 nm, than to yellow-green light, for example, light with a wavelength of 500-550 nm, and so the luminous flux as perceived by the sensitivity of the human eye is increased by the additional phosphor layer 7.

[0029] The additional phosphor layer 7 preferably has a minimum width W to ensure that a wide area of ​​the housing 3 remains transparent so that the optical efficiency of the lighting device 1 is not excessively impaired by the addition of the additional phosphor layer 7. The width W is preferably selected so that only light emitted from the window 42 enters the additional phosphor layer 7, in order to ensure that the width of the additional phosphor layer remains minimal. The additional phosphor layer 7 may have any suitable chemical composition. In certain embodiments, the phosphor in the additional phosphor layer 7 has the same chemical composition as the phosphor in the resin coating 40, but it is also possible for the phosphor in the additional phosphor layer 7 to have a different chemical composition than the phosphor in the resin coating 40. As will be readily understood by those skilled in the art, the thickness of the additional phosphor layer 7 should preferably be selected so that all unconverted light emitted by the filament 10 is converted as it passes through the additional phosphor layer 7. The additional phosphor layer 7 may be a resin layer in which phosphor particles are suspended. The resin layer may have the same composition as the resin coating 40, or it may have a different composition. Naturally, other support materials for the phosphors in the further phosphor layer 7 can also be considered.

[0030] A particular class of lighting devices that can benefit from the teachings of the present invention is a tubular lighting device. Figure 3 schematically shows such a lighting device 1, in which the housing 3 has a tubular body 6 and a filament 10 (not shown) extends in the elongation direction of the tubular body 6. In such a scenario, further phosphors 7 also extend in the elongation direction of the tubular body 6, typically, for example, on the inner or outer surface of the tubular body 6, and the tubular body 6 may support a plurality of such further phosphor layers 7, typically one for each window 42 of the filament 10. For example, if the filament 10 has two such windows 42, such as when using a rectangular transparent substrate 20, then two further phosphor layers 7 will extend along the elongation direction of the tubular body 6 such that each window 42 is optically aligned with one of the further phosphor layers 7. The use of a filament 10 within such a tubular lighting device 1 ensures that the lighting device can generate a 360° emission distribution, in contrast to tubular lighting devices that deploy a solid-state lighting element where the solid-state lighting element is mounted on a support, and the support itself is mounted on a portion of the surface of the tubular body 6, thereby preventing this portion of the tubular body 6 from transmitting light generated by the solid-state lighting element. To make such an emission distribution more omnidirectional, the tubular body 6 typically supports a diffusion layer or the like, but this reduces the optical efficiency of such a tubular lighting device, as mentioned above.

[0031] Figure 4 schematically shows one embodiment of how the filament 10 may be mounted within the permeable housing 3. The permeable housing 3 may include a pair of channels 9 into which electrode rails 62, 63 can be mounted, and the electrode rails are conductively coupled to the filament 10 via support arms 64, 65, such as support wires, which suspend the filament 10 within the permeable housing 3. For example, each electrode rail 62, 63 may be slid into the channels 9 when mounting the filament 10 into the tubular body 6, i.e., into the permeable housing 3. This is shown more clearly in Figure 5, which shows that the channels 9 include slots 99 through which the support arms 64, 65 can extend from the electrode rails 62, 63 embedded in the channels 9 to the filament 10. The channels 9 may be formed within the permeable housing 3 in any preferred manner. For example, if the permeable housing 3 includes a plastic tubular body 6, the channel 9 may be formed inside the plastic tubular body 6 when the plastic tubular body 6 is molded.

[0032] Naturally, the electrode rails 62 and 63 may be mounted within the tubular body 6 in any preferred manner. For example, if it is difficult to realize such a channel 9, for example, in the case of a glass tubular body 6, the electrode rails 62 and 63 may instead be bonded to the inner surface of the tubular body 6. This may be achieved, for example, using a UV-activated adhesive or any other suitable type of adhesive. In the case of a UV-activated adhesive, the electrode rails 62 and 63 may be coated with such adhesive and positioned within the tubular body 6, after which the tubular body 6 is exposed to UV radiation to activate the adhesive and fix the electrode rails 62 and 63 to the tubular body 6. Alternatively, at least a portion of the inner surface of the tubular body 6 may be coated with such adhesive and activated with UV light after the electrode rails 62 and 63 have been positioned within the tubular body 6. Other preferred methods for fixing the electrode rails 62 and 63 to the tubular body 6 will become apparent to those skilled in the art.

[0033] In some embodiments, the filament 10 may consist of multiple filaments 10, as schematically shown in Figures 6 and 7, in which case each filament 10 is connected to the electrode rails 62 and 63 via corresponding support arms 64 and 65. For example, each filament 10 may extend between a pair of support arms 64 and 65. This has several advantages. Firstly, it allows each filament 10 to be connected in parallel to the electrode rails 62 and 63, thus reducing the resistance encountered when driving the solid-state lighting element 30 along each filament 10. As a result, for example, the voltage drop between the ends of the solid-state lighting element 30 extending along the tubular body 6 is smaller due to this parallel connection of the filaments 10, and therefore the requirements for the driver of the solid-state lighting element 30 are not so stringent. This means that the driver can be smaller, which makes it easier to mount the driver inside the end cap of the tubular body 6. Secondly, using multiple smaller filaments 10 instead of a single filament 10 extending along the entire length of the tubular body 6 makes it easier to create a robust lighting device 1.

[0034] The additional phosphor layer 7 is optically aligned with a window 42 on the side of the permeable support 20 within the filament 10. The additional phosphor layer 7 is shown on the outer surface of the permeable housing 3, but it should be reiterated that the additional phosphor layer 7 may also be located on the inner surface of the permeable housing 3, in which case the additional phosphor layer is less susceptible to accidental damage, for example, by scratching the outer surface of the permeable housing 3, but if the concern of such accidental damage is limited, positioning the additional phosphor layer 7 on the outer surface of the permeable housing 3 may be more cost-effective. In certain embodiments, each of the additional phosphor layers 7 covers a portion of the tubular body 6 having a radial width in the range of 60 to 90°. For example, Figure 8 schematically shows a cross-sectional view of the tubular lighting device 1, in which case the radial width of the additional phosphor layer 7 is 60°, as indicated by a pair of 30° sections on both sides of the horizontal plane separating the additional phosphor layer 7, whereas in Figure 9, each of the additional phosphor layers 7 has a radial width of 90°. As previously mentioned, the (radial) width W of each of the additional phosphor layers 7 is typically selected so that all unconverted light emitted through the window 42 facing the side surface of the transparent substrate 20 within the filament 10 is incident on such an additional phosphor layer 7, and the actual width W is a function of the dimensions and positioning of the filament 10 within the transparent housing 3, such as the thickness d of the transparent substrate 20.

[0035] Figure 10 schematically shows an exploded assembly diagram of an exemplary tubular lighting device 1 according to the present invention. One or more filaments 10 typically extend between opposing end caps 5 mounted on both ends 61, 67 of a translucent, or more preferably transparent, tubular body 6, with at least one of the end caps 5 housing a driver configuration 70 for one or more filaments 10. Preferably, as described above, if multiple filaments 10 are present in the transparent tubular housing 6, the filaments 10 are connected in parallel to electrode rails 62, 63 via support arms 64, 65, and the electrode rails 62, 63 may be mounted in channels 9 inside the tubular body 6. This reduces the voltage drop between the ends of the solid lighting element 30 on the filaments 10 along the tubular body 6, thereby reducing the voltage that the driver configuration 70 must supply, and thus making it easier to mount the driver configuration 70 in the end cap 5 by keeping the driver configuration 70 compact. Although the additional phosphor layer 7 is shown on the outer surface of the tubular body 6, it should be noted again that it is equally possible for the additional phosphor layer 7 to be located on the inner surface of the tubular body 6.

[0036] Figure 11 schematically shows an alternative embodiment of the tubular lighting device 1 of the present invention, in which a single filament 10 extends along a tubular body 6, so that a first end 11 of the single filament 10 is positioned close to the end portion 61 of the tubular body 6, and a second end 13 on the opposite side of the single filament 10 is positioned close to the opposite end portion 67 of the tubular body 6. The filament 10 may be supported within the tubular body 6 in any preferred manner. For example, the filament 10 may be pressed between opposing end caps 5, or the filament 10 may be supported by a driver configuration 70 at the first end 61 of the tubular body 6, and by a support member 75 extending from the end portion 13 of the filament and the end cap 5 at the opposite end 67 of the tubular body 6.

[0037] The driver configuration 70 may be mounted in any preferred location, for example, inside the end cap 5 of the end portion 61 of the tubular body 6. In this embodiment, the driver configuration 60 is electrically connected to the filament 10 via a first connector 72 at the first end 11 of the filament 10, and via a second connector 74 extending from the driver configuration 70 to the second end 13 of the filament 10. The second connector 74 may be a separate wire or the like, or a conductive track running on the transparent substrate 20 of the filament 10, for example, on the side 24, or on the main surface 26 opposite the mounting surface 22 supporting the solid-state lighting element 30. Alternatively, the conductive track may run on the inner surface of the tubular body 6, in which case the conductive track is preferably made of an optically transparent conductive material, such as indium tin oxide, so that the conductive track does not interfere with the light emission distribution of the tubular lighting device 1.

[0038] An illumination device 1 according to an embodiment of the present invention may be manufactured according to a manufacturing method 100, the flowchart of which is shown in Figure 12. Method 100 begins in operation 102 with preparing a transparent substrate 20, such as a transparent sapphire substrate, a transparent white ceramic substrate, a polymer substrate such as a polyimide substrate, and in operation 104 with mounting a plurality of solid illumination elements 30 on the substrate to create a filament 10. The solid illumination elements 30 may be mounted on the transparent substrate 20 in any preferred manner, and such mounting techniques are well known, so this will not be described in further detail for the sake of brevity.

[0039] Next, in operation 106, the filament 10 is surrounded with a phosphor-containing resin coating 40, for example, by immersing the filament 10 in a bath containing the coating, or by any other preferred method. As described in more detail above, the resin coating 40 typically includes at least one region 42, for example, two regions or windows 42 facing the side wall 24 of the transparent substrate 20, which will leak out the light produced by the solid-state lighting element 30 that has not been converted by the phosphor in the resin coating 40 when the filament 10 is in use. In a preferred embodiment, a transparent housing 3, for example, a glass housing or a plastic housing, which may take the shape of a tubular body 6, is prepared in operation 108 and the filament 10 is mounted therein.

[0040] Further phosphor layers 7 are formed on a portion of the transparent housing 3 such that, in operation 110, each region or window 42 of the resin coating 40 can be optically aligned with the further phosphor layers 7. For example, in the case of a bulbous transparent housing 3, a single further phosphor layer 7 may be formed extending across the bulbous transparent housing 3, thereby allowing a pair of oppositely oriented regions or windows 42 of the resin coating 40 to be optically aligned with different sections of the single further phosphor layer 7. Alternatively, in the case of a tubular transparent housing 3, a pair of further phosphor layers 7 may be formed extending along the elongation direction of the tubular transparent housing 3, thereby allowing each region or window 42 of the resin coating 40 to be optically aligned with one of the further phosphor layers 7. As can be understood from the above, one or more further phosphor layers 7 are sized based on the dimensions of the filament 10, for example, the thickness d of the transparent substrate 20, and the positioning of the filament 10 within the transparent housing 3. The additional phosphor layer 7 may be formed on a section of the inner or outer surface of the transparent housing 3 by any preferred method, for example, using conventional masking techniques. For example, the tubular body 6 may be partially filled with a D-shaped plug, leaving the section where the additional phosphor layer 7 will be formed exposed. The exposed section is then filled with a liquid resin containing the additional phosphor until the liquid reaches the plug, as disclosed, for example, in Chinese Patent Application Publication No. 1763890, and the resin is then cured (for example, using a hot airflow or UV light, depending on the type of resin), and the plug is removed from the tubular body 6.

[0041] Finally, before method 100 ends in operation 114, in operation 112, the filament 10 is mounted in the transparent housing 3. In operation 112, the filament 10 may be mounted in the transparent housing 3 by aligning each of the regions 42 of the resin coating with the additional phosphor layers 7 on the transparent housing 3 such that each of the additional phosphor layers 7 is optically aligned with one or more of the regions 42 of the resin coating 42, thereby positioning the additional phosphor layers 42 to receive unconverted light leaking from the regions 42 of the resin coating 40. In the case of a bulbous transparent housing 3, the filament 10 may be supported by an end cap 5 and extend from this end cap 5 into the transparent housing 3.

[0042] If the transparent housing 3 is formed as a tubular body 6, and each of the additional phosphor layers 7 extends along the tubular body, method 100 may further include the step of forming a filament assembly by mounting a plurality of filaments 10 on a pair of electrode rails 62, 63 such that corresponding regions 42 of each filament that leak out light generated by the solid-state lighting element 30, which has not been converted by the phosphor, are aligned with each other. Each filament 10 in this filament configuration may be electrically connected to each of the electrode rails 62, 63 by corresponding support arms 64, 65 extending between the electrode rails 62, 63 and the filament 10. In this case, operation 112 further includes the step of installing the filament assembly in the tubular body 6 such that the electrode rails 62, 63 extend along the tubular body, for example by sliding the electrode rails 62, 63 in the channel 9, or by bonding the electrode rails 62, 63 to the inner surface of the tubular body 6 after the electrode rails 62, 63 have been positioned in the tubular body 6.

[0043] Alternatively, if a single filament 10, for example, a filament 10 that extends substantially along the length of a tubular body 6, is mounted inside such tubular body 6, the operation 112 of method 100 may further include the steps of forming a first connection 72 between the driver 70 and a first terminal portion 11 of the filament 10, and forming a second connection 74 between the driver 70 and a second terminal portion 13 of the filament 10 opposite to the first terminal portion 11. In this case, the step of installing the filament 10 inside the tubular body 6 may further include the step of installing the filament 10 such that the driver 70 is located at the first end 61 of the tubular body 6 and the second terminal portion 13 of the filament 10 is located close to the second end 67 of the tubular body 10 opposite to the first end 61 of the tubular body 6, and the step of installing a support structure 75 between the second terminal portion 13 of the filament 10 and the second end 67 of the tubular body 6, for example, between the second terminal portion 13 of the filament 10 and the end cap 5 of the second end 67 of the tubular body 6, in order to stabilize the filament 10 inside the tubular body 6.

[0044] By examining the drawings, this disclosure, and the appended claims, variations of the disclosed embodiments can be understood by those skilled in the art and carried out in the course of the claimed invention. In the claims, the word “comprising” does not preclude other elements or steps, and the indefinite article “a” or “an” does not preclude plural.

[0045] The mere fact that certain means are enumerated in different dependent claims does not indicate that combinations of these means cannot be used advantageously.

[0046] When the term "adapted to" is used in a claim or the text of the specification, it is intended to be equivalent to the term "configured to".

[0047] No reference numeral in the claims should be construed as limiting the scope.

Claims

1. A lighting device, Transparent housing and, The filament within the transparent housing includes a transparent substrate that supports a plurality of solid lighting elements, A phosphor-containing resin coating surrounding the filament, comprising a resin coating having a reduced thickness that allows light generated by the solid-state lighting element, which has not been converted by the phosphor, to leak out, A lighting device in which the transparent housing supports a further phosphor layer covering a portion of the transparent housing, the further phosphor layer being optically aligned with each of the regions of the resin coating having reduced thickness, each of the further phosphor layers being positioned to receive the unconverted light leaking from at least one of the regions, and the rest of the housing remains uncovered by the further phosphor layer.

2. The lighting device according to claim 1, wherein the transparent substrate includes a mounting surface for supporting at least some of the solid lighting elements and a pair of sides on both sides of the mounting surface, each of which is covered by one of the regions of the resin coating.

3. The transparent substrate further includes a further mounting surface opposite to the mounting surface, and the side surface extends between the mounting surface and the further mounting surface. The solid-state lighting elements are distributed across the mounting surface and the further mounting surface. The lighting device according to claim 2.

4. The lighting device according to claim 1, wherein the transparent substrate is a sapphire substrate.

5. The lighting device according to claim 1, wherein each of the further phosphor layers is disposed on the inner or outer surface of the transparent housing.

6. The lighting device according to claim 1, wherein the transparent housing is a transparent housing made of glass or plastic.

7. The lighting device according to any one of claims 1 to 6, wherein the transparent housing is formed as a tubular body.

8. The lighting device according to claim 7, wherein the transparent housing includes a pair of further phosphor layers, each extending along the tubular body and having a radial width in the range of 60 to 90°.

9. Multiple filaments extending within the tubular body, A pair of electrode rails extending within the tubular body, wherein each filament is electrically connected to each of the electrode rails by a corresponding support arm extending between one of the electrode rails and the filament, The lighting device according to claim 7 or 8, further comprising the above.

10. The lighting device according to claim 9, wherein the tubular body is a plastic body having a pair of channels within its inner surface, and each of the channels extends along the tubular body and accommodates one of the electrode rails.

11. The lighting device according to claim 7 or 8, wherein the filament extends along the tubular body, and the lighting device further comprises a driver at a first end of the tubular body, the driver having a first connection portion to a first terminal portion of the filament adjacent to the first end, and a second connection portion to a second terminal portion of the filament adjacent to a second end of the tubular body opposite to the first end.

12. The lighting device according to claim 11, further comprising a support structure extending from the second terminal portion of the filament to the second end of the tubular body.

13. A method for manufacturing a lighting device, The steps include preparing a transparent substrate and To create a filament, the steps include: attaching a plurality of solid-state lighting elements to the transparent substrate; A step of surrounding the filament with a phosphor-containing resin coating, wherein the resin coating includes at least one region having a reduced thickness that allows light generated by the solid-state lighting element, which has not been converted by the phosphor, to leak out; The steps include preparing a transparent housing for the filament, A step of forming an additional phosphor layer on a portion of the transparent housing over each of the regions of the resin coating having the reduced thickness, wherein the other portion of the housing remains uncovered by the additional phosphor layer. A method comprising the step of mounting the filament in the transparent housing by optically aligning each of the regions of the resin coating having the reduced thickness with one of the further phosphor layers, such that each of the further phosphor layers is positioned to receive unconverted light leaking from the region of the resin coating that is aligned with the further phosphor layer.

14. The permeable housing is formed as a tubular body, and each of the further phosphor layers extends along the tubular body, and the manufacturing method further, A step of forming a filament assembly by mounting a plurality of filaments to a pair of electrode rails such that the corresponding regions of each filament that leak out light generated by the solid-state lighting element, which has not been converted by the phosphor, are aligned with one another, wherein each filament is electrically connected to each of the electrode rails by a corresponding support arm extending between one of the electrode rails and the filament, The method according to claim 13, wherein the step of installing the filament in the permeable housing includes the step of installing the filament assembly in the tubular body such that the electrode rail extends along the tubular body.

15. The permeable housing is formed as a tubular body, and each of the further phosphor layers extends along the tubular body, and the manufacturing method further, The steps include forming a first connection between the driver and the first terminal portion of the filament, The process includes the step of forming a second connection between the driver and the second terminal portion of the filament opposite to the first terminal portion, The step of installing the filament in the transparent housing includes installing the filament such that the driver is located at the first end of the tubular body and the second terminal portion of the filament is located close to the second end of the tubular body opposite to the first end, and the method further includes, The method according to claim 13, further comprising the step of attaching a support structure between the second terminal portion of the filament and the second end of the tubular body.

Images