JP2007103511A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device capable of adjusting a ratio of visible light of wavelengths of 400 to 760 nm and middle and near ultraviolet rays of wavelengths of 290 to 380 nm, and of outputting light near solar light in a light emitting device using a light emitting element such as an LED chip. <P>SOLUTION: The light emitting device comprises the light emitting element 3 for generating light including middle and near ultraviolet rays of wavelengths of 290 to 380 nm; and a wavelength converter 4 for converting at least part of light emitted from the light emitting element 3 to visible light of wavelengths of 400 to 760 nm. The wavelength converter 4 contains phosphors of the average particle diameter in a range of 0.5 to 70 nm. Besides the visible light of the wavelengths of 400 to 760 nm converted by the wavelength converter 4, there is emitted light involving the middle and near ultraviolet rays of the wavelengths of 290 to 380 nm emitted by the light emitting element 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting device such as an LED light emitting device.

  The indoor lighting device is required to have higher power efficiency, lower cost, and emit light with sufficient color rendering. Light with high color rendering properties means light that can be reproduced better by the color that a person feels when the light is applied to an object and when the natural light (sunlight) is applied to the object. . In order to meet these requirements, fluorescent lamps are currently most commonly used for general lighting.

  On the other hand, currently, a light emitting device (LED light emitting device) using a light emitting element (hereinafter sometimes referred to as an LED chip) made of a semiconductor material is used as a backlight light source such as a liquid crystal. The LED light emitting device has excellent characteristics such as high power efficiency, long product life, and resistance to repeated on / off lighting. For this reason, the development which improves the price of an apparatus and the hue of the light to light-emit so that this LED light-emitting device can be utilized for illumination in the future is actively promoted.

  For example, if a blue LED chip and a phosphor that converts blue light into yellow light are combined, a part of the blue light generated by the LED chip is converted to yellow with the phosphor, The remainder of the unconverted blue light can be mixed. White LED light emitting devices that emit white light obtained by such mixing have been commercialized and are being applied to simple lighting, flashlights, and the like.

  However, although the color of light emitted from these white LED light emitting devices is white, this white light includes only blue and yellow light. For this reason, the light emitted by this light-emitting device has low color rendering properties, and the light reflected by a green or red object greatly deviates from the color of the light that natural white light (sunlight) reflects from these objects. When used for indoor lighting, there is a problem that the color of an object cannot be perceived correctly.

  In order to solve this problem, as described in the following Patent Document 1 or Patent Document 2, three types of red, green, and blue from ultraviolet rays emitted by this LED chip on an ultraviolet LED chip (400 nm or less) have recently been developed. A white LED light emitting device that emits white light that can correctly reflect the color of an object with a phosphor emitting light, that is, a white light emitting device that emits white light with high color rendering properties, has been developed, and the white LED light emitting device has been applied to lighting sources such as indoor lighting. The groundwork is getting ready.

  By the way, in recent interior lighting, in addition to the above-mentioned high power efficiency, low cost of the apparatus, and emission of light having sufficient color rendering properties, mid-ultraviolet rays (wavelength of 290 to 380 nm) Is being sought. The reason for this is as follows.

  The sunlight contains visible light having a wavelength of 400 to 760 nm and mid-ultraviolet light having a wavelength of 290 to 380 nm in a ratio of 90 to 10. This mid- and near-ultraviolet rays have the effect of activating the activity of animal and plant cells and helping animals produce the necessary vitamin D. For this reason, in order for animals and plants to maintain health, it is indispensable to receive a necessary amount of mid-ultraviolet rays. However, with the aging of today's society, the number of elderly people who have to go out due to poor footing is increasing. For these people, being able to receive near-ultraviolet rays from room lighting that emits near-ultraviolet rays while staying indoors without going out is an effective means for maintaining health.

  Also, in modern society, living spaces that are not exposed to sunlight, such as buildings and underground malls, are increasing, and it is only for human beings to irradiate light containing mid-ultraviolet rays from lighting devices in these places. It is also effective for long-lasting foliage plants. Today, there are an increasing number of cases where pets are raised indoors in apartments and apartments. In this case, pets tend to be unhealthy because the amount of received near-ultraviolet rays is reduced compared to the case where they are kept outdoors. For this reason, irradiating light including mid-ultraviolet rays from the lighting device in these places is effective not only for human beings but also for maintaining the health of pets.

  Thus, for example, some fluorescent lamps are sold under the name “true light”, which is designed so that the ratio of emitted mid-ultraviolet rays and visible rays is close to that of sunlight.

  However, in general, in an LED illumination device that combines a mid-ultraviolet ray and a phosphor, when the mid-ultraviolet ray leaks from the wavelength converter, a resin component that is installed in the LED illumination device by the mid-ultraviolet ray, for example, Since protective covers and the like are deteriorated, it is desirable to suppress mid-ultraviolet rays. For example, the following Patent Documents 1 and 2 relating to an LED lighting device that combines a light emitting element that generates mid-ultraviolet light and a phosphor describe that it is desirable that the mid-ultraviolet light generated by the light-emitting element should not leak from the wavelength converter. ing. Among these, in Patent Document 1 below, a technique for increasing the efficiency of visible light having a wavelength of 400 to 760 nm is taken, and mid-ultraviolet rays (wavelength of 290 to 380 nm) are completely converted to visible light. Moreover, in the following patent document 2, it is described that the near-ultraviolet light from the semiconductor light-emitting element should be sufficiently absorbed by optimizing each material and amount of the fluorescent layer or adding an ultraviolet absorber to the sealing body. Has been. In other words, there is no LED illumination device that effectively uses near-ultraviolet rays by intentionally releasing it from the LED illumination device.

JP 2003-298116 A JP 2002-76445 A

  An object of the present invention is to adjust the ratio of visible light having a wavelength of 400 to 760 nm and near ultraviolet light having a wavelength of 290 to 380 nm in a light emitting device using a light emitting element such as an LED chip, and outputs light close to sunlight. An object of the present invention is to provide a light emitting device capable of performing the above.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the ratio of visible light and mid-ultraviolet rays is determined by a specific light-emitting element and a wavelength converter that converts light emitted from the light-emitting element into visible light. As a result, it was found that light close to sunlight could be output, and the present invention was completed.

That is, the light emitting device according to the present invention has the following configuration.
(1) A light emitting element that generates light including at least ultraviolet light having a wavelength of 290 to 380 nm, and a wavelength converter that converts at least part of light emitted from the light emitting element into visible light having a wavelength of 400 to 760 nm. The wavelength converter contains a phosphor having an average particle diameter of 0.5 to 70 nm, and the light emitting element is generated in addition to visible light having a wavelength of 400 to 760 nm converted by the wavelength converter. A light-emitting device that outputs light including near-ultraviolet rays having a wavelength of 290 to 380 nm.
(2) The ratio of visible light having a wavelength of 400 to 760 nm and near ultraviolet light having a wavelength of 290 to 380 nm in the light output from the light emitting device is 1 to 15% of the middle ultraviolet light with respect to 85 to 99% of visible light. (1) The light-emitting device according to (1).
(3) The light emitting device according to (1) or (2), wherein the wavelength converter contains 0.5 to 20% by mass of the phosphor.
(4) The light emitting device according to any one of (1) to (3), wherein a peak wavelength of excitation light emitted from the light emitting element is 380 to 410 nm.
(5) The wavelength converter has the phosphor dispersed in a transparent solid matrix, and the solid matrix is made of at least one resin selected from the group consisting of polyethylene, polyisopropylene and silicone resin. The light emitting device according to any one of (1) to (4).

  According to the above (1) and (2), at least a part of the light emitted from the light emitting element that generates light including at least ultraviolet light having a wavelength of 290 to 380 nm and visible light (wavelength 400) is generated. And a wavelength converter for converting to 760 nm), and outputs, as output light, light including both near-ultraviolet rays having a wavelength of 290 to 380 nm and visible light having a wavelength of 400 to 760 nm. Furthermore, the wavelength converter contains a phosphor having an average particle diameter of 0.5 to 70 nm. When the average particle diameter of the phosphor is 0.5 to 70 nm, the size of the phosphor is not more than a quarter of the mid-ultraviolet wavelength, so that the mid-ultraviolet is not scattered by the phosphor. As a result, a light-emitting device in which the amount of near-ultraviolet rays generated by the light-emitting element is converted into visible light by the phosphor and the amount of mid-ultraviolet rays emitted without being converted by the phosphor is manufactured. It is possible to output light close to sunlight by adjusting the ratio between the visible light and the mid-ultraviolet light.

  In this way, the light emitting element generates light including mid-ultraviolet rays, and a part of the light obtained from the light emitting element is converted by a wavelength converter to form white visible light. A light emitting device that generates light in which white visible light and mid-ultraviolet light are mixed can be manufactured. As a result, it is possible to receive near-ultraviolet rays necessary for humans, foliage plants, and pets while staying indoors without being exposed to sunlight. Note that light emitted from the light emitting element may include mid-ultraviolet rays having a wavelength of 290 to 380 nm, and the light intensity does not necessarily have a peak at the wavelength of 290 to 380 nm.

  According to said (3), the thickness of a wavelength converter can be made thin by making the density | concentration of a fluorescent substance 0.5 mass% or more. Moreover, it can prevent that the mechanical strength of a wavelength converter falls by the density | concentration of a fluorescent substance being 20 mass% or less.

  According to (4) above, by setting the peak wavelength of the excitation light to 380 to 410 nm, it is possible to use a light emitting element having a high output provided with a light emitting layer made of a semiconductor material. As a result, a light emitting device that generates high-output visible light and mid-ultraviolet rays can be obtained.

  According to the above (5), since the solid matrix is made of at least one resin selected from the group consisting of polyethylene, polyisopropylene and silicone resin, the solid matrix does not absorb near-ultraviolet rays, and is a phosphor. Unconverted mid-ultraviolet rays can be effectively output from the light emitting device.

  The light-emitting device of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an embodiment of the light emitting device of the present invention. According to FIG. 1, the light emitting device is provided on the substrate 2 on which the electrode 1 is formed so as to cover the light emitting element 3 that generates light including at least ultraviolet light having a wavelength of 290 to 380 nm, and the light emitting element 3. And a wavelength converter 4 made of a composite of the resin 42 and the phosphor 41. Moreover, in the light-emitting device, you may provide the protective layer 5 shown in FIG. 1 as needed. The protective layer 5 in FIG. 1 is made of glass, but may be made of a material other than glass.

  In addition to the visible light converted by the wavelength converter 4, the light emitting device of the present invention outputs light including near-ultraviolet rays having a wavelength of 290 to 380 nm generated by the light emitting element 3. At this time, the ratio of the output visible light and the near-ultraviolet ray is 1 to 15% for the near-ultraviolet ray with respect to 85 to 99% for the visible light. Note that the lower limit value of the ratio of mid-ultraviolet rays is 5% or more, preferably 8% or more, and the upper limit value of the ratio of mid-ultraviolet rays is 11% or less, preferably 13% or less. The reason why such a ratio is good is that, when the amount of mid- and near-ultraviolet rays is 1% or less, the effect of activating the animals and plants obtained by irradiating the mid- and near-ultraviolet rays is reduced. Next, when the amount of mid-ultraviolet rays exceeds 15%, the mid-ultraviolet rays are output more than necessary without being converted into visible light, so that the amount of visible light that is output is reduced and a large amount of light is emitted to keep the room bright. This is because it is necessary to install a device and use a lot of electric power.

  Here, the ratio of the amount of visible light and near-infrared rays can be determined as follows. First, the intensity of light output from the light emitting device is measured for each wavelength from 290 to 760 nm. Next, by integrating each of the measurement results at a wavelength of 290 to 380 nm and a wavelength of 400 to 760 nm, respectively, and setting each of them as an amount of near-ultraviolet rays of a wavelength of 290 to 380 nm and an amount of visible light of a wavelength of 400 to 760 nm. The ratio of the amount of visible light and mid-ultraviolet rays can be determined. Such measurement and integration can be performed using, for example, a total luminous flux measurement system SLMS-1011 manufactured by labsphere.

(electrode)
The electrode 1 has a function as a conductive path for electrically connecting the light emitting element 3 and is connected to the light emitting element 3 with a conductive bonding material. As the electrode 1, for example, a metallized layer containing metal powder can be used. Specifically, it is preferable to use a metallized layer of a metal powder such as W, Mo, Cu, or Ag.

(substrate)
In the light emitting device of FIG. 1, a ceramic substrate 2 is used. As the substrate 2, for example, a polymer resin in which metal oxide fine particles are dispersed may be used in addition to a ceramic material such as alumina or aluminum nitride. As shown in FIG. 1, the substrate 2 is provided with a recess, and the light emitting element 3 is provided in the recess.

(Light emitting element)
The light emitting element 3 preferably includes a light emitting layer made of a semiconductor material in terms of high external quantum efficiency. The semiconductor material is not particularly limited as long as it is a semiconductor material that can form the light-emitting element 3 that emits light including mid-ultraviolet rays having a wavelength of 290 to 380 nm. For example, ZnSe or nitride semiconductor And various semiconductors.

In the light emitting device of the present invention, it is desirable that the peak wavelength of the excitation light emitted from the light emitting element 3 is 380 to 410 nm. An example of the material of the light emitting element 3 that generates light in this range is GaN. When a light emitting layer made of GaN is used, materials such as sapphire, spinel, SiC, Si, ZnO, ZrB ₂ , GaN, and quartz are preferably used for the light emitting element substrate on which the light emitting layer is installed. The GaN light emitting layer can be formed as a light emitting layer on a light emitting element substrate such as sapphire by a crystal growth method such as metal organic chemical vapor deposition (MOCVD method) or molecular beam epitaxial growth.

(Phosphor)
As the phosphor, it is preferable to use a phosphor made of a compound semiconductor. Although the compound semiconductor here is not particularly limited, for example, Group Ib of the periodic table, Group II (excluding Be, Hg, Ra), Group III (however, Tl, Ac series elements are used) Excluding), Group IV (excluding Pb and Hf), Group V (excluding As and Pa series), and Group VI (excluding U) Compounds. Specifically, III-V group compound semiconductors such as BN, BP, BAs, AlN, AlP, AlSb, GaN, GaP, GaSb, InN, InP, and InSb, II-VI group compound semiconductors such as ZnO and ZnS, CuInS ₂ , CuGaS ₂ , CuAlS ₂ , Cu (In _1-x Al _x ) S ₂ (x is a value represented by 0 ≦ x ≦ 1), CuInS ₂ , Cu (In _1-x Ga _x ) S ₂ (x is The value represented by 0 ≦ x ≦ 1) is preferably used.

(Wavelength converter)
The wavelength converter 4 absorbs part of the light emitted from the light emitting element 3, converts it into visible light (wavelength 400 to 760 nm), and outputs it. In the light emitting device of the present invention, the wavelength converter 4 shown in FIG. 1 is coated with a phosphor paste so as to cover the light emitting element as shown in FIG. Filling and further forming a protective layer thereon, or forming a phosphor in ink form as shown in FIG. 3, wiping and applying to the recesses of the substrate 2 and the light emitting element part 3, and coating with resin However, as shown in FIG. 1, it is preferable that the wavelength converter 4 is a composite in which a phosphor 41 is dispersed in a transparent solid matrix 42. Moreover, it is preferable that the average particle diameter of fluorescent substance is 0.5-70 nm. Hereinafter, a composite which is an example of the wavelength converter 4 will be described with reference to FIG.

  The composite shown in FIG. 1 includes a phosphor 41 and a solid matrix 42. If the average particle diameter of the phosphor 41 is 0.5 to 70 nm, the size of the phosphor 41 is not more than a quarter of the mid-ultraviolet wavelength, so that mid-ultraviolet light may be scattered by the phosphor 41. Absent. For this reason, it is possible to manufacture a light emitting device capable of outputting a stable amount with respect to the amount of mid-ultraviolet rays output from the wavelength converter 4 to the outside.

  At this time, it is preferable to prepare a composite by mixing a plurality of types of phosphors 41, for example, three or more types of phosphors 41, so that white light with higher color rendering properties can be obtained from the light emitting device. A phosphor made of the above compound semiconductor is used. The size of the phosphor 41 is preferably set to an average particle size of 20 nm or less. In this case, by changing the size (average particle diameter) of the phosphor 41, it is possible to show various light emission from red (long wavelength) to blue (short wavelength), and the wavelength of light emitted from the phosphor 41 is wide. Can be set. For this reason, the color rendering properties of the light-emitting device can be greatly improved by combining several phosphors 41 having an average particle diameter of 20 nm or less and having different average particle diameters.

  As the solid matrix 42, for example, a curable resin such as a silicone resin, an acrylic resin, or an epoxy resin, polyethylene, polyisopropylene, or the like can be used. The solid matrix 42 made of polyethylene, polyisopropylene, or silicone resin can transmit mid-ultraviolet rays well. For this reason, the solid matrix does not absorb mid-ultraviolet rays, and mid-ultraviolet rays that are not converted by the phosphor can be effectively output from the light emitting device. In particular, the silicone resin has high light stability and heat resistance. Therefore, by using a silicone resin for the solid matrix 42, the light emitting device can be used stably for a long period of time without the wavelength converter 4 turning brown. This is because the silicon-oxygen bond, which is the main structure of the silicone resin, is about 1.5 times as strong as the carbon-carbon bond, so that decomposition by light or heat hardly occurs.

  The composite preferably includes 0.1 to 50% by mass of the phosphor 41 in the solid matrix 42 with respect to the total amount of the wavelength converter 4. More preferably, it is 0.5-20 mass%. Examples of the method of mixing the phosphor 41 with the solid matrix 42 at a concentration of 0.1 to 50% by mass include the following methods. First, the phosphor 41 is added to a resin such as an uncured silicone resin, acrylic resin, or epoxy resin, and kneaded with a stirrer. After kneading, the composite can be used for the wavelength converter 4 by curing it into a predetermined shape. At this time, if the phosphor 41 is treated with a dispersant, the phosphor 41 can be uniformly dispersed in the resin. The thus obtained composite wavelength converter 4 absorbs 85 to 99% of the mid-ultraviolet rays emitted from the light-emitting element 3 and converts them into visible light, and the remaining 1 to 15% of mid-ultraviolet rays. Therefore, the amount ratio of the visible light and the mid-ultraviolet ray output from the light emitting device can be set to 1-15% of the mid-ultraviolet ray to 85-99% of the visible light. The composite of the wavelength converter 4 preferably includes a phosphor 41 having a concentration of 3 to 6% by mass in the solid matrix 42.

  As a composite, phosphor 41 is kneaded with uncured resin, and this is molded by a sheet molding method such as a doctor blade and then cured, and this is cut or punched into a predetermined size to form a film. A thing may be used. In addition, the composite may be formed by potting so as to cover the light emitting element 3 installed on the substrate 2. At this time, the thickness of the composite is preferably in the range of 0.1 to 5 mm from the viewpoint of producing a stable light emitting device.

  FIG. 2 shows another embodiment of the light emitting device of the present invention. In the light emitting device of FIG. 2, an inner layer 45 is provided between the light emitting element 3 and the wavelength converter 4, and the light emitting element 3 is covered with the inner layer 45. Such an inner layer 45 can be formed by filling and curing a resin such as a silicone resin. The other parts are the same as those in FIG. 1 described above, and thus the same reference numerals are given and description thereof is omitted. By providing the inner layer 45, the wavelength converter 4 previously formed on the film can be used. Thereby, it becomes easy to control the thickness of the wavelength converter 4, and it is easy to control the timing of curing, so that it is easy to suppress precipitation of the phosphor.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited only to a following example.

[Example]
The light emitting device of FIG. 2 was produced as shown below.
(Production of phosphor)
Cadmium selenide (CdSe) nanoparticles were synthesized by a hot soap method. At this time, the surface of each CdSe nanoparticle was coated with a 1 to 2 nm zinc sulfide film. For the CdSe nanoparticles, three types of particles A to C having different fluorescence wavelengths as shown below were prepared by changing the average particle diameter.
CdSe nanoparticles A: average particle diameter, 2.1 nm; fluorescence wavelength, 520 nm
CdSe nanoparticle B: average particle diameter, 4.5 nm; fluorescence wavelength, 630 nm
CdSe nanoparticles C: average particle diameter, 5.5 nm; fluorescence wavelength, 700 nm
The average particle diameter of CdSe nanoparticles was measured as follows. A particle dispersion having a particle concentration of 0.002 to 0.02 mol / liter of CdSe nanoparticles dispersed in the solution was prepared. As the solvent, IPA or toluene is used.
Next, the microgrid for TEM observation is immersed in this particle dispersion to attach particles, and is left in a desiccator at room temperature to dry the particle dispersion, and the microgrid for TEM observation in which CdSe nanoparticles are attached to the surface. To prepare for measurement.
The magnification was 500,000 to 1,000,000 times, and focusing was performed so that the lattice fringes of the particles could be seen, and the particle diameter was measured using 200 or more particles as a sample on the enlarged photograph of the obtained TEM image. If the particle size is large and the entire particle does not enter the field of view, check the TEM image at a magnification that allows the entire particle to enter the field of view after confirming that it is a primary particle at a high magnification at which lattice fringes can be seen. Was measured. The particle diameter of the CdSe nanoparticles was observed with a transmission electron microscope (TEM) JEM2010F manufactured by JEOL at an acceleration voltage of 200 kV.
At this time, the CdSe nanoparticles to be photographed are intended only for the portion where the lattice stripes are visible, and organic substances such as organic ligands adsorbed on the particle surface are not included in the diameter of the lattice image.
The diameter of the measured lattice image was calculated statistically by writing a histogram to calculate the length average diameter. The length average diameter was calculated by counting the number of particles belonging to the diameter group and dividing the sum of the product of the center value and the number of the diameter group by the total number of particles measured (average particle size). Diameter shape and its calculation formula, “Ceramic Manufacturing Process” p.11-12, edited by Ceramic Industry Association Editorial Committee Lecture Subcommittee). The length average diameter thus calculated was treated as the average particle diameter of CdSe nanoparticles.
The image obtained by TEM observation was copied on a transparent resin film sheet, and it was confirmed that the measurement was possible by a method of obtaining the average particle diameter of the particles with an image analysis processor.

(Example 1: Production of wavelength converter and light-emitting device)
CdSe nanoparticles A to C were mixed with a condensation type silicone resin so as to be 2.7% by mass, 2.2% by mass, and 1.1% by mass, respectively, with respect to the total amount of the wavelength converter 4 to be obtained. After being molded by the blade method, it was cured at 80 ° C. to form a composite film having a thickness of 2 mm.
At this time, the dispersion state and particle diameter of the CdSe nanoparticles inside the composite were confirmed by TEM.
After the composite is sliced to 100 nm or less by the ultrathin section method, a portion of about 30 nm is subjected to TEM observation as a guide. At this time, if the resin is too soft and thinning is difficult, the resin is frozen with liquid nitrogen and processed, and then subjected to TEM observation.
The particle diameter of the CdSe nanoparticles was observed with a transmission electron microscope (TEM) JEM2010F manufactured by JEOL at an acceleration voltage of 200 kV.
After confirming the presence / absence of aggregation of CdSe nanoparticles at 500,000 times again, the lattice image of CdSe nanoparticles was observed at a magnification of 4,000,000 times.
In addition, 200 nanophosphor particles having a confirmed lattice image were selected, and the diameter of the lattice image of each nanophosphor particle was measured. The diameter of the measured lattice image was statistically calculated by writing a histogram in the same manner as described above to calculate the length average diameter, and this was regarded as the particle diameter of the CdSe nanoparticles.
Next, this was punched out to a diameter of 2 mm to obtain a wavelength converter 4. Thereafter, the wavelength converter 4 was arranged on the light emitting element 3 mounted on the previously prepared ceramic (alumina) substrate to produce a light emitting device. The light emitting element 3 was a chip made of InGaN-GaN having a light emission wavelength of 395 nm and a size of 0.35 mm × 0.35 mm. When the intensity of light emitted from this light emitting device was measured in the wavelength range of 290 to 760 nm, light with a wavelength of 290 to 380 nm was 7.8%, and visible light with a wavelength of 400 to 760 nm was 92.2%. I was able to get it.

(Examples 2 to 14)
A light emitting device was produced in the same manner as in Example 1 except that the mixing ratio of the phosphors (CdSe nanoparticles A to C) was changed to the ratio shown in Table 1.

  According to the said Example, it turns out that the light-emitting device which light-emits the visible light of the ratio shown in Table 1, and a mid-ultraviolet ray was able to be manufactured. Moreover, as shown in Table 1, the ratio of visible light and mid-ultraviolet rays can be adjusted by the amount of phosphor added.

It is a schematic explanatory drawing which shows embodiment of the light-emitting device of this invention. It is a schematic explanatory drawing which shows embodiment of the light-emitting device of this invention provided with the inner layer. It is a schematic explanatory drawing which shows other embodiment in the light-emitting device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode 2 Board | substrate 3 Light emitting element 4 Wavelength converter 5 Protective layer 41 Phosphor 42 Solid matrix 45 Inner layer

Claims (5)

A light emitting element that generates light including at least ultraviolet light having a wavelength of 290 to 380 nm, and a wavelength converter that converts at least part of the light emitted from the light emitting element into visible light having a wavelength of 400 to 760 nm,
The wavelength converter contains a phosphor having an average particle size of 0.5 to 70 nm,
In addition to visible light having a wavelength of 400 to 760 nm converted by the wavelength converter, the light emitting device outputs light including near-ultraviolet rays having a wavelength of 290 to 380 nm generated by the light emitting element.   The ratio of visible light having a wavelength of 400 to 760 nm and mid-ultraviolet light having a wavelength of 290 to 380 nm in the light output from the light emitting device is 1 to 15% of mid-ultraviolet light with respect to 85 to 99% of visible light. The light-emitting device according to claim 1.   The light emitting device according to claim 1, wherein the wavelength converter contains 0.5 to 20% by mass of the phosphor.   The light emitting device according to claim 1, wherein a peak wavelength of excitation light emitted from the light emitting element is 380 to 410 nm. The wavelength converter disperses the phosphor in a transparent solid matrix,
The light-emitting device according to claim 1, wherein the solid matrix is made of at least one resin selected from the group consisting of polyethylene, polyisopropylene, and silicone resin.

Images