Light-emitting devices providing improved visual comfort

Abstract

The light-emitting device 100 includes a light-transmitting bulb 101 having a bulb wall 110 surrounding a cavity 120 of the bulb 101. An LED filament 102 is disposed within the cavity 120 of the bulb 101, and a connecting means 103 is attached to the bulb 101 and configured to connect the LED filament 102 to a power source 150. The bulb wall 110 has an outer shell 111, an inner shell 112, and an intermediate structure 113. The intermediate structure 113 is disposed between the outer shell 111 and the inner shell 112, and the intermediate structure 113 is textured on a spatial scale such that a portion of light 160 emitted by the LED filament 102 is reflected as diffuse light 161 towards the cavity 120.

Description

[Technical Field]

[0001] The present invention relates generally to light emitting devices, and more particularly to a light emitting device having a translucent bulb surrounding a cavity within which a light emitting diode (LED) filament is disposed. [Background technology]

[0002] The original electrically powered light bulb lamps were of the type that had a metal wire filament enclosed in a more or less evacuated glass bulb. This type of light bulb lamp was the ubiquitous choice of light source for over a century until the introduction of LEDs. LED-based light sources are now replacing light bulbs as a source of light in homes and many other places. Initially, primarily due to the inherent structural characteristics of LEDs, early LED light sources (i.e., LED lamps) did not resemble previous light bulbs and were often considered aesthetically inferior to previous types of light bulbs. Thus, once it became technically possible to create light sources using LED filaments, the desire for light sources that had the appearance of traditional light bulb-shaped filament lamps returned for aesthetic reasons.

[0003] In today's LED filament light sources, many small LEDs are closely mounted on a wire or thin strip, and these LEDs are embedded in phosphor, which, when powered, provides a light output that looks to a large extent similar to early metal wire filament light bulbs.

[0004] However, a disadvantage of current LED filament lamps is that they can be uncomfortable to look into due to the high contrast between the brightness of the LED filament and the background. Summary of the Invention [Problem to be solved by the invention]

[0005] It would be interesting to provide a light source that improves viewing comfort, thereby overcoming the disadvantages of current LED filament light sources. [Means for solving the problem]

[0006] This and other objects are achieved in a first aspect by providing a light emitting device having the features of the accompanying independent claims. Preferred embodiments are defined in the accompanying dependent claims.

[0007] Therefore, according to the present invention, there is provided a light emitting device including a light transmissive bulb having a bulb wall surrounding a cavity of the bulb. An LED filament is disposed within the cavity of the bulb, and connection means are attached to the bulb and configured to connect the LED filament to a power source. The bulb wall has an outer shell, an inner shell, and an intermediate structure. The intermediate structure is disposed between the outer shell and the inner shell, and the intermediate structure is textured on a spatial scale so that a portion of the light emitted by the LED filament is reflected as diffuse light toward the cavity.

[0008] For example, the intermediate structure may be configured as a texture on the inside of the outer shell. Additionally or alternatively, the intermediate structure may be configured as a texture on the outside of the inner shell.

[0009] Thereby, the intermediate structure is applied to the inside of the outer shell or to the outside of the inner shell and is therefore part of the inner and / or outer shell, and in a preferred embodiment, the intermediate structure forms a monolithic part of the outer and / or inner shell.

[0010] In other words, the internal structure of the translucent bulb wall diffusely reflects a portion of the light emitted by the LED filament. This has the effect of reducing the contrast between the direct light from the LED filament and the diffusely reflected light, as experienced by an observer looking at the LED filament through the bulb. At the same time, the view of the LED filament itself, as experienced by the observer, is not significantly blurred. Furthermore, because the reflected light undergoes further reflections and exits the bulb, no light is lost. Therefore, assuming low absorption, most of the light exits the bulb as useful light. This effect has the advantage of improving the observer's visual comfort and thus overcoming the aforementioned disadvantages of current LED filament light sources.

[0011] In some embodiments, the intermediate structure has essentially the same spatial extent as the spatial extent of the outer shell and the inner shell in terms of surrounding the cavity.

[0012] Such a configuration provides improved visual comfort regardless of the direction from which the observer is looking at the LED filament through the bulb.

[0013] In some embodiments, the intermediate structure has a spatial extent, in terms of surrounding the cavity, that is smaller than the spatial extent of the outer shell and the inner shell.

[0014] For example, the intermediate structure may be spatially subdivided to have a plurality of intermediate structure subdivisions, and in some embodiments of such a configuration, the intermediate structure subdivisions may have at least a first type of texture and a second type of texture.

[0015] Such a configuration provides enhanced visual comfort in viewing directions determined by the spatial extent of the diffusely reflecting intermediate structure. Thus, for example, it is possible to configure the intermediate structure to be textured only in one or more desired specific portions of the bulb, such that this specific portion provides diffuse reflection of light only in the desired specific direction.

[0016] In some embodiments, the intermediate structure includes a material that provides the intermediate structure with spectral selectivity with respect to the wavelength interval of the diffused light that is reflected.

[0017] For example, in an embodiment having an intermediate structural section, the intermediate structural section may have at least a first type of material and a second type of material, the first type of material and the second type of material having different spectral selectivities with respect to the wavelength interval of the reflected diffused light.

[0018] For example, such materials may include multiple dielectric layers and / or semi-transparent metal layers.

[0019] By providing the intermediate structure with spectral selectivity for the reflected diffuse light, it is possible to construct a light-emitting device with a desired color contrast: the light emitted by the LED filament and viewed directly through the bulb has a first color, and the diffusely reflected light has a second color, thereby providing enhanced visual comfort. Thus, embodiments with intermediate structural sections may provide an enhanced viewer experience, in that the appearance of light in terms of color may change depending on the viewer's position.

[0020] In some embodiments, the intermediate structure comprises a micro-optical structure, and in some embodiments, the intermediate structure comprises a surface roughness.

[0021] By choosing a particular type of texture, it is possible to determine the properties of the reflected diffuse light. For example, using micro-optical structures, the reflected diffuse light can be shaped into a narrow or wide beam of light, or even into multiple images of the LED filament.

[0022] In some embodiments, the outer shell and the inner shell have the same refractive index.

[0023] By configuring the light emitting device so that the outer shell and the inner shell have the same refractive index, the remaining portion of the light emitted by the LED filament that is not diffusely reflected by the textured intermediate structure is transmitted through the outer and inner shells largely unaffected in terms of being unblurred, which means that the view of the LED filament within the bulb, as seen by the observer, is not obstructed by the inner and outer shells.

[0024] The object of providing a light source that improves visual comfort and thereby overcomes the disadvantages of current LED filament light sources is further achieved in a further aspect by a method for manufacturing a light emitting device, the method comprising a texturing step, a surrounding step, and a connecting step. The texturing step includes providing an intermediate structure on the inside of an outer shell and / or providing an intermediate structure on the outside of an inner shell. The surrounding step includes joining the inner shell and the outer shell to form a bulb wall that surrounds a light-transmitting bulb cavity. The connecting step includes disposing an LED filament in the cavity and attaching connecting means to the bulb, the connecting means being configured to connect the LED filament to a power source.

[0025] In some embodiments, the texturing step further comprises providing the intermediate structure with a material that imparts spectral selectivity to the intermediate structure with respect to a wavelength interval of the reflected diffuse light.

[0026] The method of this further aspect provides effects and advantages corresponding to those summarized above in relation to the first aspect.

[0027] Other objects, features, and advantages of the present invention will become apparent upon study of the following detailed disclosure, drawings, and appended claims. Those skilled in the art will appreciate that different features of the present invention may be combined to create embodiments other than those described below. [Brief explanation of the drawings]

[0028] This and other aspects of the invention will now be described in more detail with reference to the accompanying drawings, in which embodiments of the invention are shown. [Figure 1] 1 shows a schematic side view of a light emitting device; [Figure 2a] 1 shows a schematic representation of a micro-optical structure. [Figure 2b] 1 shows a schematic representation of a micro-optical structure. [Figure 2c] 1 shows a schematic representation of the surface roughness structure. [Figure 3] 1 shows a schematic side view of a light emitting device; [Figure 4] 1 shows a schematic side view of a light emitting device; [Figure 5] 1 is a flowchart of a method for manufacturing a light emitting device. DETAILED DESCRIPTION OF THE INVENTION

[0029] Figure 1 shows a light emitting device 100 including a light transmissive bulb 101 having a bulb wall 110 that encloses a cavity 120 of the bulb 101. As illustrated in Figure 1, the bulb 101 is essentially spherical, as indicated by the circular outline of the bulb 101. Note that a particular shape of the bulb 101 is not required, and to illustrate this fact, alternative bulb shapes are illustrated below in connection with Figure 3.

[0030] An LED filament 102 is disposed within the cavity 120 of the bulb 101. Although not apparent from Figure 1, the LED filament 102 is in the form of many small LEDs closely attached to a wire or thin strip.

[0031] The bulb 101 is fitted with a connection means 103, which is configured to connect the LED filament 102 to a power source 150. Details regarding such electrical connection between the LED filament 102 and the power source 150 are outside the scope of this disclosure.

[0032] The bulb wall 110 has an outer shell 111, an inner shell 112, and an intermediate structure 113. The outer shell 111 and the inner shell 112 are made of any suitable material known to those skilled in the art, such as transparent glass or polymer. The intermediate structure 113 is disposed between the outer shell 111 and the inner shell 112. The intermediate structure 113 is textured on a spatial scale so that a portion of the light 160 emitted by the LED filament 102 is reflected as diffuse light 161 toward the cavity 120.

[0033] The manner in which the actual arrangement of intermediate structures 113 is made between outer shell 111 and inner shell 112 is described below in connection with Figures 2a-2c. In some embodiments, intermediate structures 113 are configured as a texture on the inside of outer shell 111, and in some embodiments, intermediate structures 113 are configured as a texture on the outside of inner shell 112.

[0034] 1, the intermediate structure 113 has essentially the same spatial extent as the spatial extent of the outer shell 111 and the inner shell 112 in terms of surrounding the cavity 120. Other embodiments in which the intermediate structure 114 has a spatial extent that is smaller than the spatial extent of the outer shell 111 and the inner shell 112 in terms of surrounding the cavity 120 are illustrated below in connection with Figures 3 and 4. As described below in connection with Figure 4, the intermediate structure 114 may, in some embodiments, be spatially subdivided to have a plurality of intermediate structural sections 115, and these intermediate structural sections 115 may have at least a first type of texture and a second type of texture.

[0035] During operation, the power supply 150 supplies power to the LED filament 102, which then emits light. The spatial distribution of the light emission is determined by the orientation of the LED filament 102. Most of the light is emitted transversely to the direction in which the LED filament 102 extends, and a small amount of light is emitted longitudinally of the LED filament 102. This is illustrated in FIG. 1 by emitted light 160. An observer 170 views the lighting device 100 from a location outside the bulb 101. The emitted light 160 is partially reflected by the intermediate structure 113 as diffuse light 161, and a portion of the emitted light 160 reaches the observer 170 directly through the bulb 101 without being diffusely reflected, as illustrated by direct light 162. Note that the arrows representing the diffuse light 161 and the direct light 162 are not intended to indicate any relative amounts of light, but only to qualitatively indicate the respective portions of light.

[0036] From the point of view of the observer 170, the effect is that direct light 162 passes through the bulb 101 towards the observer 170 without being affected by the interfaces formed by the shells 111, 112, 113, causing the observer 170 to get a clear image of the LED filament 102. However, part of the light 160 that reaches the intermediate structure 113 is scattered in reflection and diffusely reflected back into the cavity 120, thereby observable by the observer 170 in the form of diffuse light 161, so that the LED filament 102 appears less bright to the observer 170. As a result, the observer 170 sees both a clear, less bright image of the LED filament 102 and a blurred background glow.

[0037] In some embodiments, the outer shell 111 and the inner shell 112 may have the same refractive index. In that case, the direct light 162 resulting from the transmission of the emitted light 160 through the shells 111, 112, 113 is substantially unaffected. This means that the view of the LED filament 102, as seen by the observer 102, is not obscured by the inner shell 112 and the outer shell 111.

[0038] The intermediate structure 113 may include a material that provides the intermediate structure 113 with spectral selectivity with respect to the wavelength interval of the reflected diffuse light 161. For example, such material may be in the form of multiple dielectric layers or semi-transparent metal layers. Such multiple dielectric layers or semi-transparent metal layers may be applied during manufacture, for example in the form of a coating, to either the inside of the outer shell 111 or the outside of the inner shell 112, or to both the inside of the outer shell 111 and the outside of the inner shell 112.

[0039] For example, in an embodiment in which the intermediate structure 114 is spatially subdivided to have multiple intermediate structure sections 115, the intermediate structure sections 115 may have at least a first type of material and a second type of material, where the first type of material and the second type of material have different spectral selectivities with respect to the wavelength interval of the reflected diffused light 161.

[0040] 2a illustrates a close-up view of an embodiment of a light-emitting device 100 in which intermediate structures 113 include micro-optical structures 116 configured as a texture inside the outer shell 111. Such micro-optical structures 116 may be in the form of multiple microlenses as illustrated in FIG.

[0041] Figure 2b illustrates a close-up view of an embodiment of light-emitting device 100 in which intermediate structure 113 includes micro-optical structures 116 configured as a texture on the outside of inner shell 112. As in the example of Figure 2a, such micro-optical structures 116 may be in the form of multiple microlenses as illustrated in Figure 2b.

[0042] 2c illustrates a close-up view of an embodiment of light-emitting device 100 in which intermediate structure 113 includes a surface roughness 117 configured as a texture on the outside of inner shell 112. Although not shown, a similar intermediate structure 113 can be obtained by providing such a surface roughness 117 on the inside of outer shell 111.

[0043] By considering the reflective properties of the semi-reflective intermediate structure 113 and configuring such micro-optical structures 116 or surface roughness 117 with respect to their characteristic parameters, it is possible to configure the intermediate structure 113 with a reflectivity in the range of 10% to 80%, thereby obtaining a desired level of contrast between the direct light 162 and the diffused light 161, and thereby configuring the lighting device 100 to provide the desired visual comfort to the observer 170.

[0044] FIG. 3 illustrates a light-emitting device 100 similar to the lighting device 100 illustrated in FIG. 1. The lighting device 100 in FIG. 3 includes a light-transmitting bulb 101 having a bulb wall 110 surrounding a bulb cavity 120. Like the bulb 101 illustrated in FIG. 1, the bulb 101 is essentially spherical, as indicated by the circular outline of the bulb 101. An LED filament 102 is disposed within the bulb cavity 120, and a connecting means 103 is attached to the bulb 101 for connecting the LED filament 102 to a power source 150. The bulb wall 110 includes an outer shell 111, an inner shell 112, and an intermediate structure 114. The outer shell 111 and the inner shell 112 are made of any suitable material known to those skilled in the art, such as transparent glass or polymer. The intermediate structure 114 is disposed between the outer shell 111 and the inner shell 112, as described and illustrated above. In contrast to the intermediate structure 113 illustrated in FIG. 1, the intermediate structure 114 in FIG. 3 has a spatial extent that is smaller than the spatial extent of the outer and inner shells 111 and 112 in terms of enclosing the cavity 120 .

[0045] Generally, this means that the intermediate structures 114 are provided on only a portion of the outer shell 111 and / or inner shell 112. Specifically, in Figure 3, the intermediate structures 114 are hemispherical, thereby providing diffuse reflection of light only in a limited angular interval around the bulb 101.

[0046] FIG. 4 illustrates a light-emitting device 100 similar to the lighting device 100 illustrated in FIG. 1. The lighting device 100 in FIG. 4 includes a light-transmitting bulb 101 having a bulb wall 110 surrounding a bulb cavity 120. In contrast to the bulb 101 illustrated in FIG. 1, the bulb 101 in FIG. 4 is essentially elliptical. An LED filament 102 is disposed within the bulb cavity 120, and a connecting means 103 is attached to the bulb 101 for connecting the LED filament 102 to a power source 150. The bulb wall 110 includes an outer shell 111, an inner shell 112, and an intermediate structure 115. The outer shell 111 and the inner shell 112 are made of any suitable material known to those skilled in the art, such as transparent glass or polymer. The intermediate structure 114 is disposed between the outer shell 111 and the inner shell 112, as described and illustrated above. In contrast to the intermediate structure 113 illustrated in Figure 1, the intermediate structure 114 in Figure 4 has a spatial extent in terms of surrounding the cavity 120 that is smaller than the spatial extent of the outer shell 111 and the inner shell 112. Specifically, in Figure 4, the intermediate structure 114 is in the form of a plurality of intermediate structure sections 115, thereby providing diffuse reflection of light only in limited angular intervals around the periphery of the bulb 101.

[0047] 5 is a flow chart illustrating a method of manufacturing the light emitting device 100 described and illustrated above. The method comprises a texturing step 501, a surrounding step 503, and a connecting step 505.

[0048] The texturing step 501 includes providing an intermediate structure on the inside of the outer shell 111. The intermediate structure may be any of the intermediate structures 113, 114, 115 in Figures 1, 2a-2c, and 3. Alternatively, or in addition, the texturing step 501 may include providing the intermediate structures 113, 114, 115 on the outside of the inner shell 112. In practice, providing the intermediate structures 113, 114, 115 may involve etching or molding a structure on the inside of the outer shell 111, and then applying a liquid to the textured inside of the outer shell 111 that hardens, thereby forming the inner shell 112. Alternatively, or in addition, providing the intermediate structures 113, 114, 115 may involve etching or molding a structure on the outside of the inner shell 112, and then applying a liquid to the textured outside of the inner shell 112 that hardens, thereby forming the outer shell 111.

[0049] The texturing step 503 may, in some embodiments, further include providing the intermediate structures 113, 114, 115 with a material that provides the intermediate structures 113, 114, 115 with spectral selectivity with respect to the wavelength interval of the reflected diffuse light 161. As exemplified above, such material may be in the form of multiple dielectric layers or semi-transparent metal layers. Accordingly, such layers may be applied to the inside of the outer shell 111 and / or the outside of the inner shell 112 prior to forming the inner or outer shell, respectively.

[0050] The enclosing step 503 involves joining the inner shell 111 and the outer shell 112 into a bulb wall 110 that encloses the cavity 120 of the light-transmitting bulb 101 .

[0051] The connecting step 505 includes disposing the LED filament 102 in the cavity 120 and attaching a connecting means 103 to the bulb 101 , the connecting means 103 being configured to connect the LED filament 102 to the power source 150 .

[0052] Those skilled in the art will appreciate that the present invention is in no way limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, the bulb 101 and the LED filament 102 may have different shapes, dimensions, and / or sizes than those shown / described.

Claims

1. a light-transmitting bulb having a bulb wall surrounding a bulb cavity; an LED filament disposed within the cavity of the bulb; a connection means attached to the bulb, the connection means being configured to connect the LED filament to a power source, the valve wall has an outer shell and an inner shell, and at least one of the outer shell and the inner shell has an intermediate structure disposed inside the outer shell and / or outside the inner shell; A light-emitting device, wherein the intermediate structure is configured as a spatial-scale texture such that a portion of the light emitted by the LED filament is reflected as diffuse light towards the cavity.

2. 10. The light emitting device of claim 1, wherein the intermediate structure forms a monolithic portion of at least one of the outer shell and the inner shell.

3. 3. A light-emitting device according to claim 1 or 2, wherein the intermediate structure has essentially the same spatial extent as the spatial extent of the outer and inner shells in terms of surrounding the cavity.

4. 4. A light-emitting device according to claim 1, wherein the intermediate structure has a spatial extent, in terms of surrounding the cavity, that is smaller than the spatial extent of the outer and inner shells.

5. The light emitting device of claim 4 , wherein the intermediate structure is spatially subdivided to have a plurality of intermediate structure sections.

6. The light-emitting device of claim 5 , wherein the intermediate structural section has at least a first type of texture and a second type of texture.

7. 7. A light-emitting device according to any one of claims 1 to 6, wherein the intermediate structure comprises a material that provides the intermediate structure with spectral selectivity with respect to the wavelength interval of the diffused light that is reflected.

8. A light-emitting device as described in claims 7 and 5, or claims 7 and 6, wherein the intermediate structural section has at least a first type of material and a second type of material, and the first type of material and the second type of material have different spectral selectivities with respect to the wavelength interval of the reflected diffused light.

9. The material is a plurality of dielectric layers; and 9. A light emitting device according to claim 7 or claim 8, comprising any semi-transparent metal layer.

10. 10. A light-emitting device according to any one of the preceding claims, wherein the intermediate structure comprises a micro-optical structure.

11. 11. The light-emitting device according to claim 1, wherein the intermediate structure has a surface roughness.

12. 12. The light-emitting device of claim 1, wherein the outer shell and the inner shell have the same refractive index.

13. 10. A method for manufacturing the light emitting device of claim 1, comprising the steps of texturing, surrounding, and connecting, comprising: the texturing step includes providing an intermediate structure on the inside of an outer shell and / or providing an intermediate structure on the outside of an inner shell; the surrounding step includes joining the inner shell and the outer shell to form a bulb wall that surrounds a light-transmitting bulb cavity; The method, wherein the connecting step includes disposing an LED filament within the cavity and attaching connecting means to the bulb, the connecting means configured to connect the LED filament to a power source.

14. 14. The method of claim 13, wherein the texturing step further comprises providing the intermediate structure with a material that imparts spectral selectivity to the intermediate structure with respect to the wavelength interval of the diffused light that is reflected.

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