JP7599111B2 - Light-emitting devices for mesopic environments, outdoor lighting devices, and emergency lighting devices - Google Patents

Description

The present invention relates to a light-emitting device, an outdoor lighting device, and an emergency lighting device, and in particular to a light-emitting device, an outdoor lighting device, and an emergency lighting device for use in mesopic vision environments.

Light-emitting devices that use LEDs (Light Emitting Diodes) as a light source are becoming more and more popular due to the increasing power output of LEDs. Illumination devices using LEDs for use in street spaces and the like were designed with priority given to luminous efficiency in order to ensure illuminance. In recent years, as the power output of LEDs has increased, light-emitting devices are being required to emit white light that makes the colors of objects in the illumination space appear natural, that is, with high color rendering properties. In light-emitting devices that achieve such high color rendering properties, the mainstream method is to combine LEDs with multiple types of phosphors to obtain white light, but in this case, there is an issue that the luminous efficiency decreases and it is difficult to achieve both luminous efficiency and color rendering properties.

In response to the problem of the difficulty of achieving both high luminous efficiency and high color rendering, it has been proposed to combine Mn-activated fluoride complex phosphors, including KSF phosphors, as red phosphors among the multiple phosphors used in light-emitting devices (Patent Document 1). KSF phosphors exhibit line-shaped luminous characteristics and emit little light in the long-wavelength region where visibility is low, making it possible to realize a light source that achieves both high luminous efficiency and high color rendering.

Patent No. 5840540

Meanwhile, street spaces at night are mesopic vision environments, and in such mesopic vision environments, different photoreceptor cells are stimulated than in photopic vision environments, which are bright environments. Specifically, in mesopic vision environments, the peak value of the spectral luminous efficiency that humans perceive as bright is 555 nm, and in addition to stimulating the cone cells that are primarily stimulated in photopic vision environments, rod cells, which have a peak value of the spectral luminous efficiency that humans perceive as bright at 507 nm, are also stimulated. Therefore, in order to improve visibility in mesopic vision environments, a lighting design different from that in photopic vision environments is required.

The present invention has been made in consideration of the above-mentioned reasons, and aims to provide a light-emitting device etc. that improves visibility in mesopic vision environments.

In order to achieve the above object, a light emitting device according to one aspect of the present invention comprises a solid-state light emitting element that emits light having an emission peak wavelength of 430 nm to 480 nm, a yellow-green phosphor having a half-width of 100 nm to 120 nm and an emission peak wavelength of 535 nm to 565 nm, and a fluorescent member that contains at least a KSF phosphor and emits light when excited by light from the solid-state light emitting element, and emits a composite light of the light emitted by the solid-state light emitting element and the light emitted by the fluorescent member, and in the spectrum of the composite light, the ratio of the light intensity at a wavelength of 480 nm to the light intensity at a wavelength of 580 nm is 65% to 80%, the correlated color temperature of the composite light is 4600 K to 5500 K, and the average color rendering index of the composite light is 80 or more.

In addition, a light emitting device according to one aspect of the present invention includes a solid-state light emitting element that emits light having an emission peak wavelength of 430 nm to 480 nm, and a fluorescent member that is excited by light from the solid-state light emitting element and contains at least a yellow-green phosphor and a KSF phosphor having a half-width of 100 nm to 140 nm and an emission peak wavelength of 550 nm to 580 nm, and emits light of a different wavelength. The light emitting device emits a composite light of the light emitted by the solid-state light emitting element and the light emitted by the fluorescent member, and in the spectrum of the composite light, the ratio of the light intensity at a wavelength of 480 nm to the light intensity at a wavelength of 590 nm is 30% to 50%, the correlated color temperature of the composite light is 2600 K to 3250 K, and the average color rendering index of the composite light is 80 or more.

An outdoor lighting device according to one aspect of the present invention is disposed at a height of 2 m to 15 m from the ground, irradiates the ground with the composite light, and includes a light-emitting unit having the light-emitting device described above, and the average horizontal illuminance of the irradiation surface on the ground onto which the composite light is irradiated is 5 lx to 30 lx.

An emergency lighting device according to one aspect of the present invention is an emergency lighting device that is installed in a structure, is placed at a height of 2 m or more from the floor surface of the structure, and is equipped with a light-emitting unit having the above-mentioned light-emitting device.

The light-emitting device according to the present invention improves visibility in mesopic environments.

FIG. 1 is a perspective view of the appearance of a white light source according to a first embodiment. FIG. 2 is a schematic cross-sectional view of the white light source taken along line II-II in FIG. FIG. 3 is a diagram showing an example of the spectrum of white light emitted by the white light source according to the first embodiment. FIG. 4 is a diagram showing the spectrum of white light emitted by the white light source in Comparative Example 1. FIG. 5 is a diagram showing the spectrum of white light emitted by the white light source in the first embodiment. FIG. 6 is a diagram showing the spectrum of white light emitted by the white light source in the second embodiment. FIG. 7 is a diagram showing the spectrum of white light emitted by the white light source in the third embodiment. FIG. 8 is a diagram showing the spectrum of white light emitted by the white light source in Comparative Example 2. FIG. 9 is a diagram showing the spectrum of white light emitted by the white light source in Comparative Example 3. FIG. 10 is a perspective view of an external appearance of a white light source according to a modification of the first embodiment. FIG. 11 is a schematic cross-sectional view of the white light source taken along line XI-XI in FIG. FIG. 12 is a diagram illustrating an example of the spectrum of white light emitted by a white light source according to a modification of the first embodiment. FIG. 13 is a diagram showing the spectrum of white light emitted by the white light source in Comparative Example 4. FIG. 14 is a diagram showing the spectrum of white light emitted by the white light source in Example 4. FIG. 15 is a diagram showing the spectrum of white light emitted by the white light source in Example 5. FIG. 16 is a diagram showing the spectrum of white light emitted by the white light source in Example 6. FIG. 17 is a diagram showing the spectrum of white light emitted by the white light source in Comparative Example 5. FIG. 18 is an external view of an outdoor lighting device according to the second embodiment. FIG. 19 is an external view of an emergency lighting device according to the third embodiment.

The following embodiments are described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept are described as optional components. Furthermore, the diagrams are schematic diagrams in which emphasis, omissions, or ratios have been appropriately adjusted to illustrate the present invention, and are not necessarily strictly illustrated, and may differ from the actual shapes, positional relationships, and ratios.

(Embodiment 1)
[composition]
First, the configuration of the light emitting device according to the first embodiment will be described.

Figure 1 is an external perspective view of a white light source 100 according to embodiment 1. Figure 2 is a schematic cross-sectional view of the white light source 100 taken along line II-II in Figure 1. In this specification, the white light source 100 is an example of a light-emitting device.

As shown in Figs. 1 and 2, the white light source 100 according to the first embodiment is realized as a surface mount device (SMD) type light emitting device. As described below, the white light source 100 can emit white light that is perceived as bright in a mesopic vision environment. For this reason, the white light source 100 is suitable for outdoor lighting devices used in dark environments such as at night.

The white light source 100 may be a remote phosphor type light emitting device. The white light source 100 may be a chip on board (COB) type light emitting device.

The white light source 100 comprises a container 111 having a recess, a sealing member 112 sealed in the recess, a solid-state light-emitting element 113 mounted in the recess, and a fluorescent member 116 dispersed in the sealing member 112. In Figs. 1 and 2, the white light source 100 has a rectangular parallelepiped shape, but is not limited to this and may have other shapes such as a cylindrical shape or a hemispherical shape.

The container 111 is a container that houses the solid-state light-emitting element 113 and the sealing member 112. The container 111 also has an electrode 114, which is a metal wiring for supplying power to the solid-state light-emitting element 113. The solid-state light-emitting element 113 and the electrode 114 are electrically connected by a bonding wire 115. The material of the container 111 is, for example, a metal, a ceramic, or a resin.

As the ceramic, aluminum oxide (alumina) or aluminum nitride is used. As the metal, for example, an aluminum alloy, an iron alloy, or a copper alloy with an insulating film formed on the surface is used. As the resin, for example, glass epoxy made of glass fiber and epoxy resin is used. The container 111 may be made of a combination of the above materials.

The sealing member 112 is a translucent resin material that seals at least a portion of the solid-state light-emitting element 113, the bonding wire 115, and the electrode 114, and has the fluorescent material 116 dispersed therein. The translucent resin material is not particularly limited, but examples thereof include silicone resin, epoxy resin, and urea resin.

The solid-state light-emitting element 113 is a light-emitting element having a peak emission wavelength of 430 nm or more and 480 nm or less. The peak emission wavelength of the solid-state light-emitting element 113 may be 440 nm or more and 460 nm or less. By setting the peak emission wavelength of the solid-state light-emitting element 113 to 430 nm or more, the light emission efficiency of the fluorescent member 116 is likely to be high, and the light emission efficiency of the white light source 100 is likely to be high. By setting the peak emission wavelength of the solid-state light-emitting element 113 to 480 nm or less, the light emission efficiency of the solid-state light-emitting element 113 is likely to be high, and the light emission efficiency of the white light source 100 is likely to be high. For example, a blue LED that emits blue light is used as the solid-state light-emitting element 113. For example, a gallium nitride LED made of an indium gallium nitride material is used as a specific blue LED.

The fluorescent member 116 contains yellow-green phosphor 117a and KSF phosphor 117b, and is excited by a portion of the light emitted from the solid-state light-emitting element 113 to emit light.

The yellow-green phosphor 117a is a phosphor that is excited by a portion of the light emitted from the solid-state light-emitting element 113 and emits yellow-green light having a half-width of 100 nm or more and 120 nm or less and an emission peak wavelength of 535 nm or more and 565 nm or less. By making the half-width 100 nm or more, the color rendering of the light emitted by the white light source 100 is improved. By making the half-width 120 nm or less, the luminous efficiency of the white light source 100 is improved. As the yellow-green phosphor 117a, one type of yellow-green phosphor may be used, or a combination of multiple types of phosphors that emit wavelengths from blue-green to yellow may be used. Specifically, examples of the yellow-green phosphor 117a include (Y,Lu) ₃ (Al, _Ga ) _5O12 : _Ce , (Y _, Gd) ₃ (Al _, Ga) _5O12 :Ce, _CaSc2O4 :Ce, _Ca3Sc2Si3O12 : _Ce , ₍ La,Y) _{3Si6N11 :} Ce, (Sr,Ca _{,Ba)2SiO4:Eu, (Sr,Ca,Ba)3SiO5 : Eu ,} and _β -sialon phosphor. Among these, the yellow-green phosphor 117a _may preferably contain a phosphor having a Ce-activated garnet structure such as (Y,Lu) ₃ (Al,Ga) _5O12 :Ce, (Y,Gd) ₃ (Al,Ga) _5O12 :Ce, etc. When the yellow-green phosphor _117a contains a phosphor having a Ce-activated garnet structure, a white light source 100 having high luminous efficiency is easily obtained, and when the white light source 100 is used in a lighting device, the luminous efficiency of the lighting device is also increased.

The KSF phosphor 117b is excited by a part of the light emitted from the solid-state light-emitting element 113 to emit red light. The KSF phosphor 117b is a red phosphor represented by the general formula (M1) ₂ ((M2) _1-x Mn _x ) F _6. M1 is at least one alkali metal element selected from Li, Na, K, Rb, and Cs, M2 is at least one tetravalent metal element selected from Ge, Si, Sn, Ti, and Zr, and x satisfies 0.00<x≦0.5. A representative composition formula of the KSF phosphor 117b is K ₂ (Si, Mn) F _6. The KSF phosphor 117b has a bright line-shaped red emission peak with an emission wavelength of 625 nm or more and 635 nm or less in the emission spectrum.

As the red phosphor of the fluorescent member 116, the KSF phosphor 117b may be used alone, or a phosphor that combines the KSF phosphor 117b with another red phosphor (such as an Eu-activated nitride phosphor or an Eu-activated oxynitride phosphor) may be used.

The mixing ratio and amount of the yellow-green phosphor 117a and the KSF phosphor 117b contained in the fluorescent member 116 are adjusted so that the white light emitted by the white light source 100 has the spectrum, correlated color temperature, and average color rendering index described below.

[Action]
Next, the operation of white light source 100 according to the first embodiment will be described.

When power is supplied to the white light source 100, the solid-state light-emitting element 113 emits blue light. A portion of the blue light emitted by the solid-state light-emitting element 113 is absorbed by the yellow-green phosphor 117a and wavelength-converted to yellow-green light. Similarly, another portion of the blue light emitted by the solid-state light-emitting element 113 is absorbed by the KSF phosphor 117b and wavelength-converted to red light. Then, the blue light not absorbed by the yellow-green phosphor 117a and the KSF phosphor 117b, the yellow-green light emitted by the yellow-green phosphor 117a, and the red light emitted by the KSF phosphor 117b are diffused and mixed in the sealing member 112, and white light, which is a composite light, is emitted. In other words, the white light source 100 emits white light, which is a composite light of the light emitted by the solid-state light-emitting element 113 and the light emitted by the fluorescent member 116 containing the yellow-green phosphor 117a and the KSF phosphor 117b. By using this configuration to produce white light of the desired chromaticity, the output ratio of each light becomes constant, making it possible to obtain white light with little chromaticity deviation. The color deviation of the white light is preferably in the range of -10 to +2, and more preferably in the range of -7 to +0. By having the color deviation of the white light in this range, it is possible to make the irradiated object in the lighting space stand out more while still maintaining a natural white color. In addition, the correlated color temperature of the white light is 4600K to 5500K, and the average color rendering index of the white light is 80 or more. This results in a white light source 100 that emits daylight white light with high color rendering properties.

FIG. 3 is a diagram showing an example of the spectrum of white light emitted by the white light source 100. As shown in FIG. 3, in the spectrum of white light, the ratio (Xa/Xb) of the light intensity Xa at a wavelength of 480 nm to the light intensity Xb at a wavelength of 580 nm is 65% or more and 80% or less. Xa/Xb may be 65% or more and 75% or less. By making Xa/Xb 65% or more, the white light contains a lot of light with wavelengths from blue to blue-green that easily stimulate rod cells, so that visibility in a mesopic vision environment is improved. Furthermore, since the effect of making things look vivid is improved, if the irradiated object is a colored object, the colored object becomes more noticeable, so that the presence of the colored object becomes easier to notice. In addition, by making Xa/Xb 80% or less, the illuminance is increased even with the same amount of input current, and visibility in a mesopic vision environment is improved. Therefore, by setting Xa/Xb in this range, it is possible to achieve both the effect of making the irradiated object stand out and the illuminance in a mesopic vision environment. In addition, the spectrum of the white light has a bright line-shaped red emission peak derived from the KSF phosphor 117b, which improves color rendering and increases the visibility of colored objects. Therefore, the lighting device using the white light source 100 has high luminous efficiency, and even in a mesopic vision environment such as a street space at night, the color appearance of the irradiated object in the lighting space is good, and visibility is improved. Therefore, it is preferable that the white light source 100 is a light-emitting device for mesopic vision environments. In this specification, mesopic vision refers to a brightness in which the adaptation luminance is in the range of 0.005 cd/m ² or more and 5 cd/m ² or less.

[Examples and Comparative Examples]
Examples and comparative examples of the white light source according to the first embodiment are described below. In the following Examples 1 to 3 and Comparative Examples 1 to 3, the white light sources were caused to emit light with the same amount of input current, and evaluations were performed. Furthermore, the white light sources in each of Examples 1 to 3 and Comparative Examples 1 to 3 are white light sources that include a solid-state light-emitting element and a fluorescent member composed of a yellow-green phosphor and a KSF phosphor.

<Visibility in mesopic environments>
The visibility in a mesopic environment in the Examples and Comparative Examples was evaluated according to the following criteria in terms of visibility in an environment where a white light source in each Example or Comparative Example was irradiated, in a dark room in which a colored object was placed, and where a white light source in Comparative Example 1 was irradiated as a reference light source. In Examples 1 to 3 and Comparative Examples 1 to 3, the white light source was emitted so as to create a mesopic environment.

Good: The surroundings appear brighter than the reference light source, making it easier to find colored objects.

Equivalent: The surroundings are visible with the same brightness as the reference light source, and colored objects are equally easy to find.

Poor: The surroundings appear darker than the reference light source, and colored objects are difficult to find.

<Evaluation items>
In addition to the visibility in the mesopic vision environment described above, the chromaticity x and chromaticity y in the CIE xy chromaticity diagram, the general color rendering index, Xa/Xb, and luminous flux of the white light emitted by the white light source in each of the examples and comparative examples were also evaluated.

<Comparative Example 1>
First, a description will be given of the white light source in Comparative Example 1. In Comparative Example 1, the solid-state light-emitting element is an LED having an emission peak at 450 nm, and the yellow-green phosphor is a phosphor having a Ce-activated garnet structure with an emission peak wavelength of 550 nm and a half-value width of 110 nm.

Figure 4 shows the spectrum of white light emitted by the white light source in Comparative Example 1. The spectrum shown in Figure 4 is achieved by adjusting the mixing ratio and amount of the yellow-green phosphor and the KSF phosphor. Table 1 shows the evaluation results of the white light source in Comparative Example 1 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, general color rendering index, Xa/Xb, and luminous flux. The white light source in Comparative Example 1 is designed to have high color rendering and luminous efficiency in a photopic environment. As shown in Table 1, the Xa/Xb of the white light source in Comparative Example 1 is 24%.

Example 1
Next, a white light source in Example 1 will be described. In Example 1, the solid-state light-emitting element is an LED having an emission peak at 450 nm, and the yellow-green phosphor is a phosphor having an emission peak wavelength at 540 nm and a half-value width of 110 nm, and having a Ce-activated garnet structure.

Figure 5 is a diagram showing the spectrum of white light emitted by the white light source in Example 1. The spectrum shown in Figure 5 is realized by adjusting the mixing ratio and mixing amount of the yellow-green phosphor and the KSF phosphor. Table 1 shows the evaluation results of the white light source in Example 1 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, average color rendering index, Xa/Xb, luminous flux, and visibility in a mesopic vision environment. In addition, compared to the white light source in Comparative Example 1, the white light source in Example 1 has a 20% increase in S/P ratio and a 15% increase in FCI (Feeling of Contrast Index). The S/P ratio is the ratio of luminous flux in scotopic vision to luminous flux in photopic vision, and is a numerical value that evaluates the visibility of light, where the higher the S/P ratio, the higher the visibility in a mesopic vision environment. The higher the S/P ratio, the easier it is to see the periphery brightly in a mesopic vision environment. FCI is an index that indicates the vividness of a color, and the higher the FCI, the more vividly an illuminated object stands out. Specifically, FCI indicates the ratio of perceived brightness to standard light D65, which is determined by color appearance. The higher the FCI, the more noticeable a colored object tends to be, making it easier to find its presence.

As shown in Table 1, the Xa/Xb of the white light source in Example 1 is 65%, and the evaluation result of visibility in a mesopic vision environment is good. Compared to the white light source in Comparative Example 1, the white light source in Example 1 has a luminous flux lower by 10 lm, but the S/P ratio and FCI are increased, so the visibility in a mesopic vision environment is improved.

Example 2
Next, a description will be given of a white light source in Example 2. The white light source in Example 2 has the same basic configuration as that in Example 1, but differs in the blending ratio and blending amount of the yellow-green phosphor and the KSF phosphor.

Figure 6 shows the spectrum of white light emitted by the white light source in Example 2. The spectrum shown in Figure 6 is achieved by adjusting the mixing ratio and amount of the yellow-green phosphor and the KSF phosphor. Table 1 shows the evaluation results of the white light source in Example 2 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, general color rendering index, Xa/Xb, luminous flux, and visibility in a mesopic vision environment. Furthermore, compared to the white light source in Comparative Example 1, the white light source in Example 2 has an S/P ratio that is increased by 20% and an FCI that is increased by 15%.

As shown in Table 1, the Xa/Xb of the white light source in Example 2 is 66%, and the evaluation result of visibility in a mesopic vision environment is good. Compared to the white light source in Comparative Example 1, the white light source in Example 2 has a lower luminous flux of 15 lm, but the S/P ratio and FCI are increased, so the evaluation result of visibility in a mesopic vision environment is improved.

Example 3
Next, a description will be given of a white light source in Example 3. The white light source in Example 3 has the same basic configuration as Example 1, but differs in the blending ratio and blending amount of the yellow-green phosphor and the KSF phosphor.

Figure 7 shows the spectrum of white light emitted by the white light source in Example 3. The spectrum shown in Figure 7 is achieved by adjusting the mixing ratio and amount of the yellow-green phosphor and the KSF phosphor. Table 1 shows the evaluation results of the white light source in Example 3 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, general color rendering index, Xa/Xb, luminous flux, and visibility in a mesopic vision environment. Furthermore, compared to the white light source in Comparative Example 1, the white light source in Example 3 has a 20% increase in S/P ratio and a 20% increase in FCI.

As shown in Table 1, the Xa/Xb of the white light source in Example 3 is 72%, and the evaluation result of visibility in a mesopic vision environment is good. Compared to the white light source in Comparative Example 1, the white light source in Example 3 has a luminous flux lower by 15 lm, but the S/P ratio and FCI are increased, so the visibility in a mesopic vision environment is improved.

<Comparative Example 2>
Next, a white light source in Comparative Example 2 will be described. In Comparative Example 2, the solid-state light-emitting element is an LED having an emission peak at 450 nm, and the yellow-green phosphor is a phosphor having a Ce-activated garnet structure with an emission peak wavelength of 540 nm and a half-value width of 105 nm.

Figure 8 shows the spectrum of white light emitted by the white light source in Comparative Example 2. The spectrum shown in Figure 8 is achieved by adjusting the mixing ratio and amount of the yellow-green phosphor and the KSF phosphor. Table 1 shows the evaluation results of the white light source in Comparative Example 2 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, general color rendering index, Xa/Xb, luminous flux, and visibility in a mesopic vision environment. Furthermore, compared to the white light source in Comparative Example 1, the white light source in Comparative Example 2 has an S/P ratio that is increased by 20% and an FCI that is also increased by 20%.

As shown in Table 1, the Xa/Xb of the white light source in Comparative Example 2 is 82%, and the evaluation result of visibility in a mesopic environment is poor. Compared to the white light source in Comparative Example 1, the white light source in Comparative Example 2 has an increased S/P ratio and FCI, but the luminous flux is reduced by 25 lm and the entire surface irradiated with white light becomes dark, resulting in reduced visibility in a mesopic environment.

<Comparative Example 3>
Next, a white light source in Comparative Example 3 will be described. In Comparative Example 3, the solid-state light-emitting element is an LED having an emission peak at 450 nm, and the yellow-green phosphor is a phosphor having a Ce-activated garnet structure with an emission peak wavelength of 545 nm and a half-value width of 110 nm.

Figure 9 shows the spectrum of white light emitted by the white light source in Comparative Example 3. The spectrum shown in Figure 9 is achieved by adjusting the mixing ratio and amount of the yellow-green phosphor and the KSF phosphor. Table 1 shows the evaluation results of the white light source in Comparative Example 3 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, average color rendering index, Xa/Xb, luminous flux, and visibility in a mesopic vision environment. Furthermore, compared to the white light source in Comparative Example 1, the white light source in Comparative Example 3 has an S/P ratio that is increased by 10%.

As shown in Table 1, the Xa/Xb of the white light source in Comparative Example 3 is 41%, and the evaluation results of visibility in a mesopic environment are the same. Compared to the white light source in Comparative Example 1, the white light source in Comparative Example 3 has a slightly increased S/P ratio, but the luminous flux is reduced by 15 lm, so the visibility in a mesopic environment remains unchanged.

<Summary>
As described above, the white light sources in Examples 1 to 3, in which the ratio Xa/Xb of the light intensity at wavelength 480 nm to the light intensity at wavelength 580 nm is in the range of 65% to 80%, have good evaluation results for visibility in a mesopic vision environment. On the other hand, when Xa/Xb exceeds 80% as in the white light source in Comparative Example 2, the evaluation results for visibility in a mesopic vision environment are poor, and when Xa/Xb is lower than 65% as in the white light source in Comparative Example 3, the evaluation results for visibility in a mesopic vision environment are equivalent. In addition, the white light sources in Examples 1 to 3 have an average color rendering index of 80 or more, and the color temperature is 4600K to 5500K based on the results of chromaticity x and chromaticity y.

(Modification)
[composition]
Next, a description will be given of a light emitting device according to a modification of embodiment 1. In the following description of the modification of embodiment 1, differences from embodiment 1 will be mainly described, and descriptions of commonalities will be omitted or simplified.

Figure 10 is an external perspective view of a white light source 200 according to a modified example of embodiment 1. Figure 11 is a schematic cross-sectional view of the white light source 200 taken along line XI-XI in Figure 10. In this specification, the white light source 200 is an example of a light-emitting device.

10 and 11, the white light source 200 is different from the white light source 100 according to the first embodiment in the fluorescent material provided therein. Specifically, the fluorescent material is changed so that the correlated color temperature of the white light emitted by the white light source 200 is lower than the correlated color temperature of the white light emitted by the white light source 100. The white light source 200 includes a container 111 having a recess, a sealing member 112 sealed in the recess, a solid-state light-emitting element 113 mounted in the recess, and a fluorescent member 216 dispersed in the sealing member 112. The container 111 includes an electrode 114, which is a metal wiring for supplying power to the solid-state light-emitting element 113. The solid-state light-emitting element 113 and the electrode 114 are electrically connected by a bonding wire 115.

The fluorescent member 216 contains yellow-green phosphor 217a and KSF phosphor 217b, and is excited by a portion of the light emitted from the solid-state light-emitting element 113 to emit light.

The yellow-green phosphor 217a is a phosphor that is excited by a portion of the light emitted from the solid-state light-emitting element 113 and emits yellow-green light having a half-width of 100 nm or more and 140 nm or less and an emission peak wavelength of 550 nm or more and 580 nm or less. By making the half-width 100 nm or more, the color rendering of the light emitted by the white light source 200 is improved. By making the half-width 140 nm or less, the luminous efficiency of the white light source 200 is improved. As the yellow-green phosphor 217a, one type of yellow-green phosphor may be used, or a combination of multiple types of phosphors that emit wavelengths from blue-green to red may be used. Specifically, the yellow-green phosphor 217a includes (Sr, Ca, Ba) ₂ Mg(SiO ₄ ) ₄ Cl ₂ :Eu, (Sr, Ca, Ba) Si ₂ O ₂ N ₂ :Eu, (Y, Lu) ₃ (Al, Ga) ₅ O ₁₂ :Ce, (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce, CaSc ₂ O ₄ : Ce, Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce, (La, Y) ₃ Si ₆ N ₁₁ : Ce, (Sr, Ca, Ba) ₂ SiO ₄ : Eu, (Sr, Ca, Ba) ₃ SiO ₅ :Eu, (Sr, Ca, Ba)AlSiN ₃ :Eu, β-sialon phosphor, α-sialon phosphor, etc. Among these, the yellow-green phosphor 217a may include a phosphor having a Ce-activated garnet structure such as (Y, Lu) ₃ (Al, Ga) ₅ O ₁₂ :Ce, (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ :Ce, etc. In addition, the yellow-green phosphor 217a may include a phosphor having a Ce-activated garnet structure and an Eu-activated nitride phosphor such as (Sr, Ca, Ba)AlSiN ₃ :Eu, etc. In addition, the yellow-green phosphor 217a may include a phosphor having a Ce-activated garnet structure and an Eu-activated oxynitride phosphor such as (Sr, Ca, Ba)Si ₂ O ₂ N ₂ , etc. The yellow-green phosphor 217a contains a phosphor having a Ce-activated garnet structure and an Eu-activated nitride phosphor or an Eu-activated oxynitride phosphor, so that the white light source 200 with high color rendering properties can be easily obtained. Therefore, when the white light source 200 is used in an illumination device, it is easy to realize an illumination space with good color reproducibility, and misrecognition of the color of the irradiated object can be suppressed.

The mixing ratio and amount of the yellow-green phosphor 217a and the KSF phosphor 217b contained in the fluorescent member 216 are adjusted so that the light emitted by the white light source 200 has the spectrum, correlated color temperature, and average color rendering index described below.

[Action]
Next, the operation of white light source 200 according to the modification of the first embodiment will be described.

The white light source 200 emits white light, which is a composite light of the light emitted by the solid-state light-emitting element 113 and the light emitted by the fluorescent member 216 containing the yellow-green phosphor 217a and the KSF phosphor 217b. By obtaining white light of the desired chromaticity with such a configuration, the output ratio of each light becomes constant, so that white light with small chromaticity deviation can be obtained. The color deviation of the white light is preferably in the range of -10 to +2, and more preferably in the range of -7 to +0. By having the color deviation of the white light in this range, it is possible to make the irradiated object in the illumination space more noticeable while still maintaining a natural white color. In addition, the correlated color temperature of the white light is 2600K to 3250K, and the average color rendering index of the white light is 80 or more. This results in a white light source 200 that emits incandescent white light with high color rendering.

Figure 12 is a diagram showing an example of the spectrum of white light emitted by the white light source 200. As shown in Figure 12, in the spectrum of white light, the white light source 200 has a ratio (Xc/Xd) of the light intensity Xc at a wavelength of 480 nm to the light intensity Xd at a wavelength of 590 nm, which is 30% or more and 50% or less. Xc/Xd may be 30% or more and 45% or less, or 30% or more and 40% or less. By making Xc/Xd 30% or more, the white light contains a lot of light with wavelengths from blue to blue-green, which are easy to stimulate rod cells, so visibility in a mesopic vision environment is improved. Furthermore, since the effect of making things look vivid is improved, if the irradiated object is a colored object, the colored object becomes more noticeable, making it easier to notice the presence of the colored object. In addition, by making Xc/Xd 50% or less, the illuminance is increased even with the same amount of input current, and visibility in a mesopic vision environment is improved. Therefore, by setting Xc/Xd in this range, it is possible to achieve both the effect of making the irradiated object stand out and illuminance in a mesopic vision environment. In addition, the spectrum of the white light has a bright line-shaped red emission peak derived from the KSF phosphor 217b, which improves color rendering and increases the visibility of colored objects. Therefore, an illumination device using a white light source 200 equipped with a solid-state light-emitting element 113 and a fluorescent member 216 has high luminous efficiency, and even in a mesopic vision environment such as a street space at night, the color appearance of the irradiated object in the illumination space is good, and visibility is increased. Therefore, it is preferable that the white light source 200 is a light-emitting device for mesopic vision environments.

[Examples and Comparative Examples]
Below, examples and comparative examples of white light sources according to modifications of embodiment 1 will be described. In the following examples 4 to 6 and comparative examples 4 and 5, the white light sources were caused to emit light with the same amount of input current, and evaluations were performed. Furthermore, the white light sources in each of examples 4 to 6 and comparative examples 4 and 5 include a solid-state light-emitting element and a fluorescent member composed of a yellow-green phosphor and a KSF phosphor.

<Visibility in mesopic environments>
The visibility of the white light source in the Examples and Comparative Examples in a mesopic vision environment was evaluated according to the following criteria in a dark room in which a colored object was placed, in which the white light source in each Example or Comparative Example was irradiated, compared to an environment in which the white light source in Comparative Example 4 was irradiated as a reference light source. In Examples 1 to 3 and Comparative Examples 1 to 3, the white light source was emitted to create a mesopic vision environment.

Good: The surroundings appear brighter than the reference light source, making it easier to find colored objects.

Equivalent: The surroundings are visible with the same brightness as the reference light source, and colored objects are equally easy to find.

Poor: The surroundings appear darker than the reference light source, and colored objects are difficult to find.

<Evaluation items>
In addition to the visibility in the mesopic vision environment described above, the chromaticity x and chromaticity y in the CIE xy chromaticity diagram, the general color rendering index, Xc/Xd, and luminous flux of the white light emitted by the white light source in each of the examples and comparative examples were also evaluated.

<Comparative Example 4>
First, a description will be given of the white light source in Comparative Example 4. In Comparative Example 4, the solid-state light-emitting element is an LED having an emission peak at 450 nm, and the yellow-green phosphor is a phosphor having an emission peak wavelength at 550 nm and a half-value width of 110 nm, and having a Ce-activated garnet structure.

Figure 12 shows the spectrum of white light emitted by the white light source in Comparative Example 4. The spectrum shown in Figure 12 is achieved by adjusting the mixing ratio and amount of the yellow-green phosphor and the KSF phosphor. Table 2 shows the evaluation results of the white light source in Comparative Example 4 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, general color rendering index, Xc/Xd, and luminous flux. The white light source in Comparative Example 4 is designed to have high color rendering and luminous efficiency in a photopic environment. As shown in Table 2, the Xc/Xd of the white light source in Comparative Example 4 is 15%.

Example 4
Next, a white light source in Example 4 will be described. In Example 4, the solid-state light-emitting element is an LED having an emission peak at 450 nm, and the yellow-green phosphor is a phosphor having an emission peak wavelength at 545 nm and a half-value width of 110 nm, and having a Ce-activated garnet structure.

Figure 13 is a diagram showing the spectrum of white light emitted by the white light source in Example 4. The spectrum shown in Figure 13 is realized by adjusting the mixing ratio and amount of the yellow-green phosphor and the KSF phosphor. Table 2 shows the evaluation results of the white light source in Example 4 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, average color rendering index, Xa/Xb, luminous flux, and visibility in a mesopic vision environment. Furthermore, compared to the white light source in Comparative Example 4, the white light source in Example 4 has an S/P ratio increased by 15% and an FCI increased by 5%.

As shown in Table 2, the Xc/Xd of the white light source in Example 4 is 37%, and the evaluation result of visibility in a mesopic vision environment is good. Compared to the white light source in Comparative Example 4, the white light source in Example 4 has the same luminous flux and an increased S/P ratio and FCI, so that visibility in a mesopic vision environment is improved.

Example 5
Next, a white light source in Example 5 will be described. In Example 5, the solid-state light-emitting element is an LED having an emission peak at 450 nm. In Example 5, the yellow-green phosphor is a phosphor adjusted to have an emission peak wavelength of 560 nm and a half-value width of 135 nm by combining a phosphor having a Ce-activated garnet structure and an Eu-activated nitride phosphor.

Figure 14 shows the spectrum of white light emitted by the white light source in Example 5. The spectrum shown in Figure 14 is achieved by adjusting the mixing ratio and amount of the yellow-green phosphor and the KSF phosphor. Table 2 shows the evaluation results of the white light source in Example 5 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, average color rendering index, Xa/Xb, luminous flux, and visibility in a mesopic vision environment. Furthermore, compared to the white light source in Comparative Example 4, the white light source in Example 5 has an S/P ratio that is increased by 17% and an FCI that is increased by 5%.

As shown in Table 2, the Xc/Xd of the white light source in Example 5 is 38%, and the evaluation result of visibility in a mesopic vision environment is good. Compared to the white light source in Comparative Example 4, the white light source in Example 5 has a luminous flux lower by 15 lm, but the S/P ratio and FCI are increased, so the visibility in a mesopic vision environment is improved.

Example 6
Next, a white light source in Example 6 will be described. In Example 6, the solid-state light-emitting element is an LED having an emission peak at 450 nm. In Example 6, the yellow-green phosphor is a phosphor adjusted to have an emission peak wavelength of 545 nm and a half-value width of 125 nm by combining a phosphor having a Ce-activated garnet structure and an Eu-activated oxynitride phosphor.

Figure 15 shows the spectrum of white light emitted by the white light source in Example 6. The spectrum shown in Figure 15 is achieved by adjusting the mixing ratio and amount of the yellow-green phosphor and the KSF phosphor. Table 2 shows the evaluation results of the white light source in Example 6 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, general color rendering index, Xa/Xb, luminous flux, and visibility in a mesopic vision environment. Furthermore, compared to the white light source in Comparative Example 4, the white light source in Example 6 has an S/P ratio that is increased by 17% and an FCI that is increased by 5%.

As shown in Table 2, the Xc/Xd of the white light source in Example 6 is 31%, and the evaluation result of visibility in a mesopic environment is good. Compared to the white light source in Comparative Example 4, the white light source in Example 6 has a luminous flux that is 20 lm lower, but the S/P ratio and FCI are increased, so visibility in a mesopic environment is improved.

<Comparative Example 5>
Next, a white light source in Comparative Example 5 will be described. In Comparative Example 5, the solid-state light-emitting element is an LED having an emission peak at 450 nm, and the yellow-green phosphor is a phosphor having a Ce-activated garnet structure with an emission peak wavelength of 540 nm and a half-value width of 110 nm.

Figure 16 shows the spectrum of white light emitted by the white light source in Comparative Example 5. The spectrum shown in Figure 16 is achieved by adjusting the mixing ratio and amount of the yellow-green phosphor and the KSF phosphor. Table 2 shows the evaluation results of the white light source in Comparative Example 5 with respect to chromaticity x and chromaticity y in the CIE xy chromaticity diagram, general color rendering index, Xa/Xb, luminous flux, and visibility in a mesopic vision environment. Furthermore, compared to the white light source in Comparative Example 4, the white light source in Comparative Example 5 has an S/P ratio that is increased by 15% and an FCI that is increased by 5%.

As shown in Table 2, the Xc/Xd of the white light source in Comparative Example 5 is 58%, and the evaluation result of visibility in a mesopic environment is poor. Compared to the white light source in Comparative Example 4, the white light source in Comparative Example 5 has an increased S/P ratio and FCI, but the luminous flux is reduced by 25 lm and the entire surface irradiated with white light becomes dark, resulting in reduced visibility in a mesopic environment.

<Summary>
As described above, the white light sources in Examples 4 to 6, in which the ratio Xc/Xd of the light intensity at wavelength 480 nm to the light intensity at wavelength 590 nm is in the range of 30% to 50%, have good evaluation results for visibility in a mesopic vision environment. In contrast, when Xc/Xd exceeds 50% as in the white light source in Comparative Example 5, the evaluation result for visibility in a mesopic vision environment is poor. In addition, the white light sources in Examples 4 to 6 have an average color rendering index of 80 or more, and from the results of chromaticity x and chromaticity y, the color temperature is 2600K to 3250K.

(Embodiment 2)
In the second embodiment, an outdoor lighting device including a white light source will be described. Fig. 18 is an external view of an outdoor lighting device 300 according to the second embodiment.

As shown in FIG. 18, the outdoor lighting device 300 is installed so as to irradiate the street 400 with white light. In this specification, the street 400 is an example of the ground. The outdoor lighting device 300 is supported above the street 400 by a columnar member 320. The outdoor lighting device 300 is used, for example, on a residential street. The outdoor lighting device 300 includes a light-emitting unit 310 having a light-emitting device 311. As the light-emitting device 311, the white light source 100 in the first embodiment or the white light source 200 in the modified example of the first embodiment is used. By using the white light source 100 or the white light source 200 as the light-emitting device 311, the outdoor lighting device 300 irradiates white light that enhances visibility in a dim light environment such as a street space at night. When the white light source 100 is used, daylight white light is irradiated, and when the white light source 200 is used, incandescent white light is irradiated.

The outdoor lighting device 300 is installed so that the light emitting unit 310 has a height H1 from 2 m to 15 m from the street 400. Outdoor lighting devices 300 are often installed at regular intervals, which can easily result in low-illumination areas on the street 400. However, by setting the height H1 within the above range, the street 400 can be illuminated more uniformly. Therefore, the effect of improving visibility even in a mesopic vision environment is uniform on the street 400.

The light emitting unit 310 irradiates light onto the street 400. Specifically, the light emitting unit 310 irradiates white light onto the irradiated surface LA of the street 400 (the hatched area of the street 400 in FIG. 18). The light emitting unit 310 is set so that the average horizontal illuminance of the irradiated surface LA is 5 lx or more and 30 lx or less. Here, the average horizontal illuminance is the illuminance per unit area of white light irradiated onto a horizontal surface. In this specification, the average horizontal illuminance refers to the average illuminance of the irradiated surface LA that the light emitting unit 310 irradiates onto the street 400. By setting the average horizontal illuminance of the irradiated surface LA within the above range, it is possible to improve visibility in a mesopic vision environment while suppressing glare felt by passersby on the street 400.

The spread angle of the white light emitted from the light-emitting unit 310 is not particularly limited as long as the street 400 is illuminated so that the average horizontal plane illuminance is within the above range. The light-emitting unit 310 is designed so that the street 400 is efficiently illuminated.

There are no particular limitations on the light-emitting unit 310 as long as it has a structure capable of irradiating light onto the street 400, but for example, it may be housed in a housing together with a power supply unit that supplies power, and the light-emitting unit 310 housed in the housing may be covered with a translucent cover. The light-emitting unit 310 may also include a lens member for controlling the distribution of light emitted from the light-emitting device 311. The light-emitting unit 310 may include at least one light-emitting device 311, and the number and arrangement of the light-emitting devices 311 that are arranged are not limited. The light-emitting unit 310 may also include a light-emitting device other than the light-emitting device 311.

As described above, the outdoor lighting device 300 is placed at a height H1 from the street 400 of 2 m to 15 m, includes a light-emitting unit 310 having a light-emitting device 311, and has an average horizontal illuminance of 5 lx to 30 lx on the irradiation surface LA. By using the white light source 100 or the white light source 200 as the light-emitting device 311, natural white light with high visibility is uniformly and naturally irradiated in a dim vision environment such as a street space at night. This makes it possible to provide an illuminated space in which the surroundings can be effectively perceived as bright, thereby improving the safety of passers-by.

(Embodiment 3)
In the third embodiment, an emergency lighting device including a white light source will be described. Fig. 19 is an external view of an emergency lighting device 500 according to the third embodiment.

As shown in FIG. 19, the emergency lighting device 500 is installed on the ceiling of a structure. The location where the emergency lighting device 500 is installed is not particularly limited as long as it can illuminate the inside of the structure, and may be, for example, a wall or a pillar of the structure. The emergency lighting device 500 is an emergency light that is turned on by battery power even in the event of a power outage due to a disaster or the like. The emergency lighting device 500 is, for example, a ceiling-embedded lighting device as shown in FIG. 19, and may be a lighting device such as a base light, ceiling light, or downlight. The emergency lighting device 500 is used, for example, in stations, hospitals, commercial facilities, and common areas of apartment buildings.

The emergency lighting device 500 includes a light-emitting unit 510 having a light-emitting device 511. The white light source 100 in the first embodiment or the white light source 200 in the modified example of the first embodiment is used for the light-emitting device 511. By using the white light source 100 or the white light source 200 as the light-emitting device 511, the emergency lighting device 500 emits white light that enhances visibility in a dim light environment where normal lighting is turned off due to a power outage. This makes it easier to recognize the position of a door, etc., even during a power outage, for example. When the white light source 100 is used, daylight white light is emitted, and when the white light source 200 is used, incandescent white light is emitted.

The emergency lighting device 500 is installed so that the light emitting unit 510 is at a height H2 of 2 m or more from the floor surface 600 of the structure. By setting the height H2 to a range of 2 m or more, the area below where the emergency lighting device 500 is installed can be uniformly illuminated.

The light-emitting unit 510 is housed in a housing together with a battery that supplies power during a power outage, for example, and the light-emitting unit 510 housed in the housing is covered with a translucent cover. The light-emitting unit 510 may also include a lens member for controlling the distribution of light emitted from the light-emitting device 511. The light-emitting unit 510 only needs to include at least one light-emitting device 511, and the number and arrangement of the light-emitting devices 511 are not limited. The light-emitting unit 510 may also include a light-emitting device other than the light-emitting device 511.

As described above, the emergency lighting device 500 is arranged in a range where the height H2 from the floor surface 600 of the structure is 2 m or more, and includes a light-emitting unit 510 having a light-emitting device 511. As a result, by using the white light source 100 or the white light source 200 as the light-emitting device 511, a natural white light with high visibility is uniformly and comfortably irradiated in a dim vision environment such as during a power outage. This makes it easier to recognize obstacles, fallen objects, doors, or signs that exist in the illuminated space, allowing people to act calmly when evacuating from the structure, and improving the safety of the evacuees.

Other Embodiments
Although the lighting device, outdoor lighting device, and emergency lighting device according to the present invention have been described based on the embodiments, the present invention is not limited to the above-described embodiments.

For example, in the above embodiment, the white light source 100 and the white light source 200 are respectively equipped with the solid-state light-emitting element 113, 213 and the fluorescent member 116, 216 having the yellow-green phosphor 117a, 217a and the KSF phosphor 117b, 217b, but this is not limited thereto. The white light sources 100 and 200 may further include a solid-state light-emitting element having an emission peak wavelength different from that of the solid-state light-emitting element 113, 213, or a fluorescent member of a different type from the fluorescent member 116, 216.

In addition, in the above embodiment, the solid-state light-emitting elements 113 and 213 are blue LEDs, but this is not limited thereto. The solid-state light-emitting elements 113 and 213 may be blue light-emitting elements capable of exciting the fluorescent members 116 and 216, respectively. For example, instead of blue LEDs, the solid-state light-emitting elements 113 and 213 may be solid-state light-emitting elements such as inorganic electroluminescence, organic electroluminescence, or semiconductor lasers.

In the above embodiment, the outdoor lighting device 300 is installed on the street 400, but this is not limited to the above. The outdoor lighting device may be installed on the ground in an outdoor space where people pass through at night, such as a park, a parking lot, a beach, a riverbank, a forest road, the grounds of an apartment complex, or the grounds of a factory.

In addition, the present invention also includes forms obtained by applying various modifications to the above-mentioned embodiments that would come to mind by a person skilled in the art, or forms realized by arbitrarily combining the components and functions of the above-mentioned embodiments without departing from the spirit of the present invention.

100, 200 White light source 113 Solid light emitting element 116, 216 Fluorescent member 117a, 217a Yellow-green phosphor 117b, 217b KSF phosphor 300 Outdoor lighting device 310, 510 Light emitting unit 311, 511 Light emitting device 400 Street 500 Emergency lighting device 600 Floor surface LA Irradiation surface

Claims (6)

A solid-state light-emitting element that emits light having an emission peak wavelength of 430 nm or more and 480 nm or less;
a fluorescent member including at least a yellow-green phosphor having a half-width of 100 nm or more and 120 nm or less and an emission peak wavelength of 535 nm or more and 565 nm or less, and a KSF phosphor which is a phosphor exhibiting a line-shaped emission characteristic , and which is excited by light from the solid-state light-emitting element to emit light;
Emitting a composite light of the light emitted by the solid-state light emitting element and the light emitted by the fluorescent member;
In the spectrum of the synthetic light, a ratio of a light intensity at a wavelength of 480 nm to a light intensity at a wavelength of 580 nm is 65% or more and 80% or less;
The correlated color temperature of the composite light is 4600 K or more and 5500 K or less,
The light emitting device for mesopic vision environments, wherein the average color rendering index of the synthetic light is 80 or more. A solid-state light-emitting element that emits light having an emission peak wavelength of 430 nm or more and 480 nm or less;
a fluorescent member including at least a yellow-green phosphor having a half-width of 100 nm or more and 140 nm or less and an emission peak wavelength of 550 nm or more and 580 nm or less, and a KSF phosphor which is a phosphor exhibiting a bright line-like emission characteristic , and which is excited by light from the solid-state light-emitting element to emit light of different wavelengths;
Emitting a composite light of the light emitted by the solid-state light emitting element and the light emitted by the fluorescent member;
In the spectrum of the synthetic light, a ratio of a light intensity at a wavelength of 480 nm to a light intensity at a wavelength of 590 nm is 30% or more and 50% or less;
The correlated color temperature of the composite light is 2600 K or more and 3250 K or less,
The light emitting device for mesopic vision environments, wherein the average color rendering index of the synthetic light is 80 or more. The light emitting device for a mesopic vision environment according to claim 1 or 2, wherein the yellow-green phosphor includes a phosphor having a Ce-activated garnet structure. The light emitting device for a dim vision environment according to claim 2 , wherein the yellow-green phosphor includes a phosphor having a Ce-activated garnet structure, and an Eu-activated nitride phosphor or an Eu-activated oxynitride phosphor. A light-emitting unit is disposed at a height of 2 m to 15 m from the ground, the light-emitting unit irradiates the ground with the synthetic light, and the light-emitting unit has the light-emitting device for mesopic vision according to any one of claims 1 to 4.
an average horizontal illuminance on an irradiation surface on the ground onto which the composite light is irradiated is 5 lx or more and 30 lx or less. An emergency lighting device installed in a structure,
An emergency lighting device, the device being disposed at a height of 2 m or more from a floor surface of the structure, the emergency lighting device comprising a light-emitting unit having the light-emitting device for mesopic vision according to any one of claims 1 to 4.

Images