JP2019087691A - Light-emitting device and image display device - Google Patents

Abstract

To provide a light-emitting device which can achieve both of a wide color gamut and a high mass productivity.SOLUTION: A light-emitting device (10a) comprises: a light-emitting element (11) operable to emit blue light; an Mnactivated γ-AlON fluorescent material (12) which emits green light when excited by the blue light; and a dispersant (13) for dispersion of the Mnactivated γ-AlON fluorescent material. The concentration of Mn included in crystal of the Mnactivated γ-AlON fluorescent material (12) is 1 wt.% or more and less than 3 wt.%. The shortest distance of a length of an optical path of the blue light formed when passing through the dispersant (13) is larger than 1 mm and equal to or smaller than 5 mm.SELECTED DRAWING: Figure 1

Description

  The following disclosure relates to a light emitting device and an image display device provided with the light emitting device.

  In recent years, (i) a light emitting element such as a light emitting diode (LED) and (ii) a wavelength conversion member which converts excitation light from the light emitting element into fluorescence (for example, phosphor particles dispersed in a resin) 2. Description of the Related Art A light emitting device in which a member) is combined is put to practical use. The light-emitting device has an advantage in that the load on the environment is lower than that of a fluorescent lamp using mercury, and the power consumption is lower than that of an incandescent lamp. Therefore, the light emitting device is widely put to practical use as a backlight source of various image display devices.

  Heretofore, the trend of improving the performance of image display devices such as liquid crystal displays has mainly been high resolution and low power consumption, and the color reproduction range of the image display device satisfies the color gamut standard of sRGB (standard RGB) Was the mainstream. This is because the color gamut of terrestrial digital broadcasting conforms to the color gamut of sRGB.

  However, in recent years, as a new competitive axis of image display devices, widening of the color gamut has begun to be rapidly realized. For example, commercialization of a wide color gamut image display device corresponding to a color gamut standard wider than sRGB such as Adobe RGB is rapidly advancing. Furthermore, next generation digital broadcasting standards for which practical broadcasting will be started in 2018 include BT. A standard called "Broadcasting Service (television) 2020", which greatly expands the conventional color gamut standard, is newly adopted. On the other hand, as a backlight source used for an image display device, BT. There is a need for light emitting devices that are compatible with the new broad color gamut standard of 2020.

  Here, the color gamut of sRGB means (CIEx, CIEy) = (0.640, 0.330), (0.300, 0. 600) on CIE (Commission Internationale de l'Eclairage) 1931 chromaticity coordinates. ), (0.150, 0.060) is a color gamut defined by a triangle surrounded by three chromaticity points. On the other hand, the color gamut of Adobe RGB means (CIEx, CIEy) = (0.640, 0.330), (0.210, 0.710), (0.150, 0.060) on the CIE 1931 chromaticity coordinates. ) Is a color gamut defined by a triangle surrounded by three chromaticity points. Furthermore, BT. The color gamut of 2020 is (CIEx, CIEy) = (0.708, 0.292), (0.170, 0.797), (0.131, 0.046) on the CIE 1931 chromaticity coordinates. It is a color gamut defined by a triangle surrounded by certain three chromaticity points. Assuming that the area of the color gamut of sRGB is 1, the area of the color gamut of Adobe RGB is 1.35, BT. The color gamut of 2020 is 1.89. In other words, compared to the display corresponding to the color gamut of sRGB, the display corresponding to Adobe RGB can express 1.35 times the color, and the BT. The display corresponding to 2020 can express 1.89 times the color.

  BT. As a light emitting device used as a backlight of a wide color gamut liquid crystal display corresponding to 2020, one having a configuration using a combination of two-color phosphors of a green phosphor and a red phosphor is suitable. Furthermore, it is preferable that the half value width of the emission spectrum of those phosphors is narrow.

For example, Patent Document 1 discloses a light emitting device using a combination of an Eu ²⁺ -activated β sialon phosphor (green phosphor) and an Mn ⁴⁺ -activated fluoride complex phosphor (red phosphor). In Table 10 and FIG. 11 of Patent Document 1, (CIEx, CIEy) = (0.685, 0.305), (0.210, 0.712), as an image display device showing a color gamut wider than AdobeRGB. What shows the color gamut of (0.156, 0.034) is illustrated. This color gamut is BT. The coverage rate is 79.8% over 2020.

Patent Document 2 discloses a light emitting device using a combination of Mn ²⁺ activated γ-AlON phosphor (green phosphor) and Mn ⁴⁺ activated fluoride complex phosphor (red phosphor). The image display device of Example D10 of Patent Document 2 has colors of (CIEx, CIEy) = (0.675, 0.298), (0.176, 0.730), (0.155, 0.030). Indicates the area. This color gamut is BT. The coverage rate is 82.8% over 2020, and a coverage rate of 80% or more can be realized.

WO / 2016/056485 JP 2017-050523 A JP, 2017-183362, A

Kenichi Yoshimura, Hiroshi Fukunaga, Makoto Izumi, Kohsei Takahashi, Rong-Jun Xie and Naoto Hirosaki “Achieving superwide-color-gamut display by using narrow-band green-emitting γ-AlON: Mn, Mg phosphor” Japanese Journal of Physics, Volume 56, Issue 4, pp. 041701 (2017)

Since the Mn ²⁺ activated γ-AlON phosphor used in the light emitting device of Patent Document 2 is a phosphor of forbidden transition, it is necessary to disperse a large amount of phosphor in a resin in order to obtain a desired white color. (Non-Patent Document 1). In such a case, the yield of the light emitting device may be reduced, and the mass productivity may be reduced.

In order to address this problem, it has been studied to improve the light absorptivity of the phosphor and reduce its dispersion amount by increasing the amount of Mn in the Mn ²⁺ -activated γ-AlON phosphor (Patent Document 3).

However, when the amount of Mn in the Mn ²⁺ -activated γ-AlON phosphor increases, the half width of the emission spectrum widens and the color gamut of the image display device decreases. It can be difficult to support extremely wide color gamut standards such as 2020.

Therefore, one embodiment of the present disclosure is a light emitting device capable of achieving both wide color gamut (high BT.2020 coverage) and high mass productivity when using Mn ²⁺ activated γ-AlON phosphor as a green phosphor. Intended to provide.

In order to solve the above problems, a light emitting device according to an aspect of the present disclosure includes: a light emitting element that emits blue light; an Mn ²⁺ activated γ-AlON phosphor that is excited by the blue light to emit green light; comprising a dispersing agent for dispersing the Mn ²⁺ activated gamma-AlON phosphor, a concentration of the ^{Mn 2+} activated gamma-AlON Mn contained in the phosphor crystals are less than 1 wt% and 3 wt%, the The shortest distance of the optical path length of the blue light formed when transmitting the dispersion material is greater than 1 mm and 5 mm or less.

  According to one embodiment of the present disclosure, it is possible to provide a light emitting device capable of achieving both wide color gamut and high mass productivity.

(A) is sectional drawing which shows the light-emitting device which concerns on Embodiment 1, (b) is sectional drawing which shows the light-emitting device which concerns on Embodiment 2. FIG. (A) and (b) are emission spectra and excitation spectra of green phosphors of Production Examples P1 and P2, and (c) and (d) are emission spectra and excitation spectra of green phosphors of Comparative Production Examples RP1 and RP2. Is a graph showing In the green phosphors of Production Examples P1 and P2 and Comparative Production Examples RP1 and RP2, the mixing ratio of raw material powder, half value of emission spectrum, peak wavelength, chromaticity coordinates, Mn concentration and measurement result of average particle diameter is there. It is a graph which shows the emission spectrum and excitation spectrum of the red fluorescent substance of manufacture example R1. (A)-(d) is a graph which shows the emission spectrum of the light-emitting device of Example DW1-DW4. Depth of resin frame, shortest distance of height of light emitting element and optical path length, and mixing ratio of green phosphor and red phosphor in light emitting devices of Examples DW1 to DW4 and Comparative Example RDW1, dispersing material (resin (resin 6 is a table showing the measurement results of the mixing ratio of the phosphor and the total amount of phosphors, mass productivity and chromaticity coordinates. The light emitting devices of Examples DW1 to DW4 and Comparative Examples RDW1 and RDW3 to RDW7 show the relationship among the shortest distance of the optical path length of blue light, the type of green phosphor, and the reduction ratio of the amount of phosphor dispersed in the dispersing material. It is a table. Depth of resin frame, shortest distance of height of light emitting element and light path length, and mixing ratio of green phosphor to red phosphor in the light emitting device of Examples DW2 and DW5 and Comparative Examples RDW2 and RDW8, Dispersing material It is a table | surface which shows the measurement result of the mixing ratio of (resin) and fluorescent substance total amount, the brightness of a light-emitting device, mass productivity, and a chromaticity coordinate. (A) is a disassembled perspective view of the image display apparatus based on Embodiment 3, (b) is a disassembled perspective view of the liquid crystal display device with which the image display apparatus shown by (a) is provided. It is a graph which shows the transmission spectrum of a color filter. It is a table | surface which shows the coverage, area ratio, and chromaticity coordinate in the image display apparatus of each Example and comparative example which concern on Embodiment 3. FIG.

Embodiment 1
<Light Emitting Device 10a>
FIG. 1A is a cross-sectional view showing the light emitting device 10a. As shown in (a) of FIG. 1, the light emitting device 10 a includes a light emitting element 11 that emits blue light, a green phosphor 12 that is excited by blue light to emit green light, and a dispersion material that disperses the green phosphor 12. A printed circuit board 14 and a resin frame 15 are provided.

  More specifically, in the light emitting device 10a, the light emitting element 11 and the resin frame 15 surrounding the light emitting element 11 are placed on the printed wiring board 14 forming the bottom surface, and the dispersion material 13 is a resin frame inside the resin frame 15. It is filled to a height of 15 to form a dispersing agent layer, whereby the light emitting element 11 is sealed. In addition, the green phosphor 12 is dispersed in the dispersing agent layer. The blue light emitted from the surface of the light emitting element 11 and the green light emitted from the green phosphor 12 excited by the blue light pass through the dispersing material layer, and the side opposite to the side where the printed wiring board 14 is located The light is emitted from the surface of the light emitting device 10a.

In one aspect of the present disclosure, Mn ²⁺ activated γ-AlON phosphor is used as the green phosphor 12 of the light emitting device 10a.

  In the present specification, the size of the light emitting device 10 a is defined by the shortest distance of the optical path length formed when blue light emitted from the light emitting element 11 passes through the dispersion material 13. The shortest distance of the optical path length means the blue light emitting surface of the light emitting element 11 (surface opposite to the surface facing the printed wiring board 14) and the light emitting surface of the dispersing material layer (printed wiring substrate 14 and It refers to the shortest distance between the opposite surface to the opposite surface, that is, the surface of the light emitting device 10 opposite to the side on which the printed wiring board 14 is located. More specifically, assuming that the depth of the resin frame 15 is L and the height of the light emitting element 11 is H as shown in FIG. 1A, in the light emitting device 10a, the shortest distance of the optical path length is (L-H).

In the light emitting device 10a including the Mn ²⁺ activated γ-AlON phosphor as the green phosphor 12, the shortest distance (L−H) of the optical path length of blue light formed when transmitting through the dispersion material 13 is larger than 1 mm, And 5 mm or less. By adjusting the size of the light emitting device (the height of the light emitting element and the height of the resin frame) such that the shortest distance of the optical path length is larger than 1 mm, the dispersing material is maintained while maintaining the desired brightness as the light emitting device. The amount of phosphor per unit volume, that is, the concentration of phosphor dispersed in the dispersing agent can be effectively reduced. Thereby, the flowability of the dispersion material in which the phosphors are dispersed is improved, and the light emitting device can be manufactured with high yield.

  Although the light emitting device in which the shortest distance of the optical path length of blue light is in the above range can be applied to various applications, it is particularly suitably used for a large image display device such as a liquid crystal television. However, if the shortest distance of the optical path length of blue light is too large, it becomes difficult to accurately install the light emitting element 11 in the resin frame 15, and the mass productivity of the light emitting device decreases or the cost of the light emitting device is high. It is not preferable because it

<Light-emitting element 11>
The light emitting element 11 is a light emitting element that emits blue light. The light emitting element 11 is not particularly limited as long as it emits blue light as primary light (excitation light) that is absorbed by the fluorescent substance and causes the fluorescent substance to emit fluorescence. For example, a gallium nitride (GaN) -based semiconductor can be used as the light emitting element 11.

The peak wavelength of the primary light (excitation light) emitted from the light emitting element 11 is preferably 440 nm or more and 460 nm or less, and more preferably 440 nm or more and 450 nm or less. Primary light having a peak wavelength in this range has good wavelength matching with the excitation spectrum of the green phosphor 12 (Mn ²⁺ -activated γ-AlON phosphor) as shown in FIG. Therefore, when the peak wavelength of the primary light is in this range, the excitation efficiency of the green phosphor 12 is enhanced, and the light emission efficiency of the light emitting element 11 is enhanced. In addition, the increase in excitation efficiency can reduce the amount of green phosphor 12 necessary to obtain the desired brightness, that is, reduce the amount of green phosphor 12 dispersed in dispersing agent 13. . Therefore, it is possible to suppress the decrease in the yield and the mass productivity of the light emitting device 10a due to the decrease in the fluidity of the dispersion material 13.

  In addition, primary light having a peak wavelength in the above range exhibits good wavelength matching with the transmission spectrum of the blue color filter 126b as shown in FIG. Therefore, it is preferable also from the point which can implement | achieve high luminous efficiency, when the light-emitting device 10a provided with the said light emitting element 11 is applied to the image display apparatus using such a color filter.

<Green phosphor 12>
The green phosphor 12 is a wavelength conversion member that emits green light by being excited by blue light emitted from the light emitting element 11, and in the present disclosure, is Mn ²⁺ activated γ-AlON phosphor.

The Mn ²⁺ activated γ-AlON used as the green phosphor 12 in the present embodiment has a composition formula M _a A _b Al _c O _d N _e (where M is Mn, Ce, Pr, Nd, Sm, Eu, GD, Tb, Among Dy, Tm, and Yb, it is one or more metal elements containing at least Mn, A is one or more metal elements other than M and Al, and in the formula, a + b + c + d + e = 1). As Mn ²⁺ -activated γ-AlON, the following (1) to (5), that is, 0.00001 ≦ a ≦ 0.1 (1)
0 ≦ b ≦ 0.40 (2)
0.10 ≦ c ≦ 0.48 (3)
0.25 ≦ d ≦ 0.60 (4)
0.02 ≦ e ≦ 0.35 (5)
Those showing a composition in a range selected from values satisfying all of the above conditions are preferably used.

In the present disclosure, the concentration of Mn contained in the crystal of the Mn ²⁺ activated γ-AlON phosphor is 1 wt% or more and less than 3 wt%. By controlling the Mn concentration in the crystal within this range, it is possible to narrow the half width of the emission spectrum of the Mn ²⁺ -activated γ-AlON phosphor and widen the color reproduction range of the image display device. When the Mn concentration in the crystal is too low, the peak wavelength of the emission spectrum of Mn ²⁺ -activated γ-AlON becomes short, and the brightness of the light emitting device decreases. Conversely, when the Mn concentration is too high, the half-width of the emission spectrum tends to be wide.

In order to stably incorporate Mn into the γ-AlON crystal, _a divalent metal element such as Mg, Zn, or Ca may be added as A of the above-mentioned composition formula M _a A _b Al _c O _d N _e Among these, Mg is particularly preferable. The inclusion of Mg in the Mn ²⁺ -activated γ-AlON phosphor stabilizes the crystal structure of the γ-AlON crystal and facilitates the incorporation of Mn into the crystal. Therefore, it becomes easy to control the Mn concentration in the crystal in a desired range, and it is possible to further improve the luminous efficiency of the Mn ²⁺ -activated γ-AlON phosphor.

The index of the Mn concentration in the crystal is an index different from the concentration of Mn in the design composition calculated from the mixing ratio of the raw material powder. That is, the concentration of Mn contained in the ^{Mn 2+} activated gamma-AlON phosphor refers to the concentration of Mn being incorporated into the crystal of ^{Mn 2+} activated gamma-AlON phosphor as a final product. Since Mn is highly volatile, it easily volatilizes during the high temperature firing process and is easily incorporated into the glass phase or heterophase outside the γ-AlON crystal. Therefore, with regard to the concentration of Mn actually incorporated into the γ-AlON crystal and contributing to light emission, the value calculated from the design composition is not used as the above index, and, for example, a crystal of Mn ²⁺ -activated γ-AlON It is preferable to use the value obtained by directly measuring the concentration of Mn in the cross section as the index. That is, it is preferable to use what calculated the density | concentration of Mn actually taken in into the crystal | crystallization as said parameter | index.

The concentration of Mn contained in the crystal of the Mn ²⁺ -activated γ-AlON phosphor can be calculated, for example, as follows. First, Mn ²⁺ activated γ-AlON phosphor powder is dispersed in an epoxy resin (manufactured by JEOL Ltd .: G-2). Next, the phosphor embedded in the epoxy resin by irradiating Ar ion beam to the epoxy resin in which the phosphor powder is dispersed, using a cross-section processing apparatus (manufactured by Nippon Denshi Co., Ltd .: SM-09010) Cut the powder. Next, an EDX (Energy dispersive X-ray spectroscopy) detector (energy dispersive X-ray analyzer) attached to the SEM apparatus (energy dispersive X-ray analyzer; manufactured by Ametech Co., Ltd .: G for a cut surface of a plurality (for example, 50 or more) phosphor powders The concentration of Mn is measured using -XM2), and the average value is calculated as the concentration of Mn.

In order to realize a wide color gamut, the half width of the emission spectrum of the Mn ²⁺ -activated γ-AlON phosphor is preferably less than 40 nm, and for example, the half width is preferably 35 nm or more and less than 40 nm.

Moreover, in order to obtain the brightness of a suitable light emitting device, the peak wavelength of the emission spectrum of the Mn ²⁺ -activated γ-AlON phosphor is preferably 516 nm or more, and for example, the peak wavelength is 516 nm or more and 526 nm or less Is preferred.

In addition, the particle diameter of the Mn ²⁺ activated γ-AlON phosphor used as the green phosphor 12 is preferably 5 μm or more and 40 μm or less in average particle diameter from the viewpoint of suppression of yield loss, and further, average particle diameter More preferably, the diameter is 10 μm or more and 30 μm or less.

  In the present disclosure, the average particle diameter is a value calculated based on a scanning electron microscope (SEM) photograph. Specifically, the area of the particle image of the electron micrograph is measured, and the particle diameter of the particle is determined as the diameter of a circle having the same area. The average particle diameter of the particles is a 50% particle diameter in a volume-based integrated fraction calculated as an average value of particle diameters determined for 100 or more randomly selected particles, and a commercially available image analyzer It can be calculated using

<Dispersing material 13>
The dispersing material 13 disperses the green phosphor 12 and is filled inside the resin frame 15 to seal the light emitting element 11.

As shown in (a) of FIG. 1, at least the green phosphor 12 composed of Mn ²⁺ activated γ-AlON phosphor is dispersed in the dispersion material 13, and the light emitting element 11 disperses the green phosphor 12. It is sealed by the dispersion material 13.

The material of the dispersing material 13 is not particularly limited. For example, a resin material having translucency such as methyl silicone resin, phenyl silicone resin, epoxy resin, acrylic resin, glass material such as low melting point glass, organic-inorganic hybrid glass Etc. can be used as appropriate. In particular, when the dispersing material 13 is made of a resin material, the temperature at the time of manufacturing the dispersing material 13 is lower than other materials, which is preferable.
<Mixing ratio of dispersing agent and phosphor>
In the present embodiment using a Mn ²⁺ activated γ-AlON phosphor in which Mn ²⁺ having a low probability of light emission and absorption transition is activated as a light emitting element as the green phosphor 12, the fluidity of the dispersing material is secured and mass productivity is achieved. In order to improve, it is preferable to control the mixing ratio of the green phosphor 12 and the dispersing agent 13 appropriately.

  Specifically, the mixing ratio of the green phosphor 12 and the dispersing agent 13 is preferably such that the ratio of the weight of the phosphor to the weight of the dispersing agent 13 is 1.2 or less, and is 1.0 or less. More preferable. In other words, (weight of green phosphor 12) / (weight of dispersion material 13) ≦ 1.2 is preferable, and (weight of green phosphor 12) / (weight of dispersion material 13) ≦ 1.0 It is more preferable that When the mixing ratio of both is in this range, it is possible to suppress the decrease in the fluidity of the dispersing material 13 in which the phosphors are dispersed, and to improve the yield and mass productivity of the light emitting device 10a. If the ratio of the green phosphors 12 is too high, the flowability of the dispersion material in which the phosphors are dispersed may be reduced, and the mass productivity of the light emitting device may be reduced.

  Moreover, it is preferable that the said weight ratio is (weight of the green fluorescent substance 12) / (weight of the dispersing material 13)> 0.3. When the mixing ratio of both is in this range, the chromaticity point of the light emitted from the light emitting device 10a can be controlled within a suitable range when applied to the image display device.

<Other members constituting light emitting device 10a>
The printed wiring board 14 is a substrate on which the light emitting element 11 is mounted and an electric circuit for driving the light emitting element 11 is formed. The resin frame 15 is a resin frame placed on the printed wiring board 14.

Second Embodiment
The light emitting device 10 b of the present embodiment differs from the light emitting device 10 a of the first embodiment in that the red phosphor 16 is dispersed together with the green phosphor 12 in the dispersion material 13. The configurations of the light emitting element 11, the green phosphor 12, the dispersion material 13, the printed wiring board 14, and the resin frame 15 are the same as the configurations described in the first embodiment.

<Light Emitting Device 10b>
(B) of FIG. 1 is a cross-sectional view showing a light emitting device 10b of the present embodiment. In the light emitting device 10b, the light emitting element 11 and the resin frame 15 surrounding the light emitting element 11 are placed on the printed wiring board 14 forming the bottom surface, and the dispersion material 13 is filled to the height of the resin frame 15 inside the resin frame 15. Thus, the light emitting element 11 is sealed. Further, the green phosphor 12 and the red phosphor 16 are dispersed in the dispersion layer. The blue light emitted from the surface of the light emitting element 11 and the green light and red light emitted from the phosphors excited by the blue light pass through the dispersing material layer and are opposite to the side where the printed wiring board 14 is located The light is emitted from the surface of the light emitting device 10b on the side.

  In the light emitting device 10 b, the shortest distance (L−H) of the optical path length of blue light formed when transmitting the dispersion material 13 is the same as the configuration described in the light emitting device 10 a of the first embodiment. I omit explanation.

<Light-emitting element 11>
The light emitting element 11 is the same as the configuration described in the light emitting device 10 a of the first embodiment.

  Also in the present embodiment, the peak wavelength of the primary light (excitation light) emitted from the light emitting element 11 is preferably 440 nm or more and 460 nm or less, and more preferably 440 nm or more and 450 nm or less. Primary light having a peak wavelength in this range is shown in FIG. 4 as well as the excitation spectrum of the green phosphor 12 as shown in FIG. 2 and the transmission spectrum of the blue color filter 126 b as shown in FIG. The wavelength matching is good also with the excitation spectrum of the red phosphor 16 which Therefore, the peak wavelength of 440 nm or more and 460 nm or less, preferably 440 nm or more and 450 nm or less is preferable from the viewpoint of improving the light emission efficiency of the light emitting device 10 b that emits white light.

<Dispersing material 13>
The dispersion material 13 disperses the green phosphor 12 and the red phosphor 16 and is filled inside the resin frame 15 to seal the light emitting element 11.

As shown in (b) of FIG. 1, the green phosphor 12 composed of Mn ²⁺ activated γ-AlON phosphor and the red phosphor 16 are dispersed in the dispersion material 13, and the light emitting element 11 Is sealed by the dispersion material 13 in which the phosphors of the above are dispersed.

The material of the dispersion material 13 is the same as the configuration described in the light emitting device 10 a of the first embodiment, and thus the description thereof is omitted.
<Mixing ratio of dispersing agent and phosphor>
The mixing ratio of the green phosphor 12 and the red phosphor 16 to the dispersing material 13 is preferably such that the ratio of the weight of the phosphor to the weight of the dispersing material 13 is 1.2 or less, and is 1.0 or less. More preferable. In other words, (weight of green phosphor 12 + weight of red phosphor 16) / (weight of dispersion 13) ≦ 1.2 is preferable, and (weight of green phosphor 12 + red phosphor 16 It is more preferable that weight / weight of the dispersing agent 13 ≦ 1.0. When the mixing ratio of both is in this range, it is possible to suppress the decrease in the fluidity of the dispersing material 13 in which the phosphors are dispersed, and the yield and mass productivity of the light emitting device 10b can be improved. If the proportion of the phosphor is too high, the flowability of the dispersing agent in which the phosphor is dispersed may be reduced, and the mass productivity of the light emitting device may be reduced.

  Further, the weight ratio is preferably (weight of green phosphor 12 + weight of red phosphor 16) / (weight of dispersing material 13)> 0.3. When the mixing ratio of both is in this range, the chromaticity point of light (for example, white light) emitted from the light emitting device 10 b can be controlled within a suitable range when applied to the image display device.

<Red phosphor 16>
The red phosphor 16 is a wavelength conversion member that is excited by the blue light emitted by the light emitting element 11 to emit red light. As such a red phosphor, an Mn ⁴⁺ activated phosphor can be suitably used.

The Mn ^{4 +} activated phosphor can be appropriately selected from the Mn ^{4 +} activated fluorine complex phosphor, the Mn ^{4 +} activated oxide phosphor, the Mn ^{4 +} activated acid fluoride phosphor, etc., among which the Mn ^{4 +} activated fluorine complex phosphor is preferable . The Mn ⁴⁺ activated fluorine complex phosphor has high excitation efficiency to blue light, and a half width of emission spectrum of emitted red light is narrow as 10 nm or less, for example, and is excellent in color reproducibility in the red region.

As the Mn ⁴⁺ activated fluorine complex phosphor used as the red phosphor 16, for example, a phosphor represented by the following general formula (A) or (B) can be used. As described above, the half width of the emission spectrum of the Mn ⁴⁺ activated fluorine complex phosphor is extremely narrow, about 10 nm or less, as described above, regardless of which of the general formula (A) and the general formula (B). This is due to the nature of the light emitting ion Mn ^{4 +} .

General formula (A): MI ₂ (MII _1-h Mn _h ) F ₆
In the above general formula (A), MI is at least one alkali metal element selected from the group consisting of Li, Na, K, Rb and Cs. MII is at least one tetravalent metal element selected from the group consisting of Ge, Si, Sn, Ti and Zr. Further, it is preferable that 0.001 ≦ h ≦ 0.1.

  In the general formula (A), MI is preferably K because of high emission intensity and high stability of the phosphor crystal. Also, for the same reason, MII preferably contains Ti or Si.

In the general formula (A), the value of h indicates the composition ratio (concentration) of Mn, that is, the concentration of Mn ⁴⁺ . If the value of h is less than 0.001, the concentration of the light emitting ion, Mn ⁴⁺ , is insufficient, and there is a problem that sufficient brightness can not be obtained. On the other hand, when the value of h exceeds 0.1, there is a problem that the brightness is largely reduced due to concentration quenching and the like.

That is, the Mn ⁴⁺ -activated fluorine complex phosphor represented by the general formula (A) is K ₂ (Ti _{1 -h} Mn _h ) F ₆ or K ₂ (Si _{1 -h} Mn _h ) F ₆ , and h is It is preferable that it is 0.001 or more and 0.1 or less.

General formula (B): MIII (MII _1-h Mn _h ) F ₆
In the above general formula (B), MIII is at least one alkaline earth metal element selected from the group consisting of Mg, Ca, Sr and Ba. MII is at least one tetravalent metal element selected from the group consisting of Ge, Si, Sn, Ti and Zr. Further, it is preferable that 0.001 ≦ h ≦ 0.1.

  In the general formula (B), MIII preferably contains at least Ba, because the luminous efficiency of the phosphor is high and the phosphor is unlikely to deteriorate due to heat and external force. For the same reason, MII preferably contains Ti or Si.

In particular, even if the Mn ^{4 +} activated fluorine complex phosphor is represented by any of the general formulas (A) and (B), if MII is Si, the solubility of the phosphor in water is low and the fluorescence It is more preferable because the water resistance of the body is enhanced. Further, in the general formula (B), the value of h indicating the composition ratio (concentration) of Mn is preferably 0.001 ≦ h ≦ 0.1, similarly to h in the above-mentioned general formula (A).

<Production of Green Phosphor 12>
Next, a production example and a comparative example of the green phosphor 12 will be described using FIGS. 2 and 3.

  (A) and (b) of FIG. 2 is a graph which shows the emission spectrum and excitation spectrum of the green fluorescent substance of manufacture example P1 and P2, respectively. On the other hand, (c) and (d) of FIG. 2 are graphs showing the emission spectrum and the excitation spectrum of the green phosphors of Comparative Production Examples RP1 and RP2, respectively.

  FIG. 3 shows the mixing ratio of the raw material powder, the half value of the emission spectrum, the peak wavelength, the chromaticity coordinates, and the incorporation into the crystals of each green phosphor in the green phosphors of Production Examples P1 and P2 and Comparative Production Examples RP1 and RP2. It is a table showing the measurement results of the Mn concentration and the average particle size of each green phosphor.

(Production Example P1)
(Firing process)
As raw material powder, 10.70% by weight of aluminum nitride powder, 79.86% by weight of aluminum oxide powder, 4.68% by weight of magnesium oxide powder, and manganese fluoride powder 4 as raw material powders in order to produce Mn ²⁺ activated γ-AlON phosphor We weighed .76 wt%. Next, these were mixed for 10 minutes or more using the mortar and pestle made from a silicon nitride sintered compact, and the powder aggregate was obtained. The obtained powder aggregate was dropped naturally into a crucible made of boron nitride having a diameter of 20 mm and a height of 20 mm.

  Next, the crucible was set in a graphite resistance heating pressurized electric furnace. Then, nitrogen having a purity of 99.999% by volume is introduced into the pressurized electric furnace, the pressure in the pressurized electric furnace is set to 0.5 MPa, and the temperature is raised to 1800 ° C. at a temperature increase rate of 500 ° C. per hour. did. Then, the crucible was held in the pressurized electric furnace at 1800 ° C. for 2 hours to obtain a phosphor sample.

(Crushing and classification process)
In a state where a small amount of pure water was added to the obtained phosphor sample, wet grinding was carried out using a mortar of agate, and coarse particles were removed while grinding the phosphor sample by passing through a sieve with an opening of 48 μm multiple times. . Thereafter, the phosphor sample from which the coarse and large powder has been removed is dispersed in an aqueous solution in which 0.1% by weight of hexametaphosphoric acid is dissolved in pure water and left for a predetermined time, and then the supernatant is removed to remove fine powder. , The particle size was adjusted to obtain a phosphor powder.

(Measurement process)
The obtained phosphor powder was subjected to powder X-ray diffraction measurement (XRD; X-ray diffraction) using a Kα ray of Cu. As a result, it was confirmed that all the charts obtained from the phosphor powder show that the phosphor powder has a γ-AlON structure. Moreover, as a result of irradiating the light of wavelength 365nm to the said fluorescent substance powder, it has confirmed that it light-emits green. That is, through the above steps, Mn ²⁺ activated γ-AlON phosphor powder was obtained.

The resulting Mn ²⁺ -activated γ-AlON phosphor is excited by irradiation with light of 445 nm using a spectrophotometer (manufactured by Otsuka Electronics: MCPD-7000), and the emission spectrum shown in FIG. I got Further, by monitoring the peak wavelength of this emission spectrum, the excitation spectrum shown in (a) of FIG. 2 was obtained.

  As a result of analyzing the obtained emission spectrum, as shown in FIG. 3, the peak wavelength of the emission spectrum of the green phosphor according to Production Example P1 was 522 nm, and the half width was 38 nm. Moreover, when the chromaticity coordinate was calculated from the said emission spectrum, it was (CIEx, CIEy) = (0.204,0.721) in CIE1931 chromaticity coordinate.

  Next, the average particle diameter of the obtained phosphor sample was measured using an electron microscope image obtained by an SEM (Scanning Electron Microscope) apparatus (manufactured by Keyence: VE-8800), and it was 13.5 μm. .

  Furthermore, the concentration of Mn incorporated into the crystals of the green phosphor according to Production Example P1 can be measured by the above-mentioned measurement method using an EDX (Energy dispersive X-ray spectrometry) detector (energy dispersive X-ray analyzer; manufactured by Ametec Co., Ltd.) It was 2.4 weight% when it measured using: G-XM2).

(Production Example P2)
Production example except that 13.53 wt% of aluminum nitride powder, 78.55 wt% of aluminum oxide powder, 5.05 wt% of magnesium oxide powder and 2.88 wt% of manganese carbonate powder were used as raw material powder In the same manner as P1, the Mn ²⁺ -activated γ-AlON phosphor of Production Example P2 was produced.

In the same manner as in Production Example P1, the obtained Mn ²⁺ -activated γ-AlON phosphor was excited to obtain the emission spectrum and the excitation spectrum shown in (b) of FIG. The peak wavelength, half value, chromaticity coordinates of this emission spectrum, and the average particle diameter and Mn concentration of the obtained phosphor sample were also measured in the same manner as in Production Example P1. The results are shown in FIG.

(Comparative Production Example P1)
Manufactured with the exception of using 10.31% by weight of aluminum nitride powder, 76.93% by weight of aluminum oxide powder, 4.5% by weight of magnesium oxide powder and 8.26% by weight of manganese fluoride powder as raw material powders. In the same manner as Example P1, the Mn ²⁺ -activated γ-AlON phosphor of Comparative Preparation Example P1 was produced.

In the same manner as in Production Example P1, the obtained Mn ²⁺ -activated γ-AlON phosphor was excited to obtain the emission spectrum and the excitation spectrum shown in (c) of FIG. The peak wavelength, half value, chromaticity coordinates of this emission spectrum, and the average particle diameter and Mn concentration of the obtained phosphor sample were also measured in the same manner as in Production Example P1. The results are shown in FIG.

The Mn ²⁺ -activated γ-AlON phosphor of Comparative Production Example P1 had an Mn concentration of 3.45% by weight incorporated into crystals.

(Comparative Production Example P2)
Comparative production in the same manner as in Production Example P1 except that 13.2% by weight of aluminum nitride powder, 85.3% by weight of aluminum oxide powder and 5.8% by weight of manganese carbonate powder were weighed and used as raw material powders. The Mn ²⁺ activated γ-AlON phosphor of Example P2 was prepared.

In the same manner as in Production Example P1, the obtained Mn ²⁺ -activated γ-AlON phosphor was excited to obtain the emission spectrum and the excitation spectrum shown in (d) of FIG. The peak wavelength, half value, chromaticity coordinates of this emission spectrum, and the average particle diameter and Mn concentration of the obtained phosphor sample were also measured in the same manner as in Production Example P1. The results are shown in FIG.

The Mn ²⁺ -activated γ-AlON phosphor of Comparative Production Example P2 had an Mn concentration of 0.45 wt% incorporated into crystals.

<Production of Red Phosphor 16>
Next, a production example of the red phosphor 16 will be described with reference to FIG. FIG. 4 is a graph showing the emission spectrum and excitation spectrum of the red phosphor of Production Example R1. In Production Example R1, an Mn ^{4 +} activated K ₂ SiF ₆ phosphor was produced as the red phosphor 16.

Production Example R1: Production of Mn ^{4 +} Activated K ₂ SiF ₆ Phosphor
In the composition formula (A) represented by MI ₂ (MII _1-h Mn _h ) F ₆ above, an Mn ^{4 +} -activated fluorine complex phosphor where MI is K, MII is Si and h = 0.06 Were prepared by the following procedure.

  First, a partition (diaphragm) of a fluorine resin-based ion exchange membrane is provided at the center of a reaction vessel made of vinyl chloride resin, and an anode and a cathode each comprising a platinum plate are provided in each of two chambers sandwiching the ion exchange membrane. did. An aqueous solution of hydrofluoric acid in which manganese (II) fluoride was dissolved was placed on the anode side of the reaction vessel, and an aqueous solution of hydrofluoric acid was placed on the cathode side.

The anode and the cathode were connected to a power supply, and electrolysis was performed at a voltage of 3 V and a current of 0.75 A. After completion of the electrolysis, when a solution of potassium fluoride saturated with an aqueous solution of hydrofluoric acid was added in excess to the reaction solution on the anode side, K ₂ MnF ₆ was produced as a yellow solid product. The resulting yellow solid product was filtered off and collected to obtain K ₂ MnF ₆ .

Next, 4.8 g of silicon dioxide was dissolved in 100 cm ³ of 48 wt% aqueous hydrofluoric acid to prepare an aqueous solution containing silicon fluoride. The aqueous solution was allowed to cool to room temperature, then placed in a resin container with a lid, kept in a water bath maintained at 70 ° C. for 1 hour or more, and warmed. In the aqueous solution containing silicon fluoride, 1.19 g of the above prepared K ₂ MnF ₆ powder was added and stirred to dissolve it, thereby preparing an aqueous solution (first solution) containing silicon fluoride and K ₂ MnF ₆ .

In addition, 13.95 g of potassium fluoride was dissolved in 40 cm ³ of a 48 wt% aqueous hydrofluoric acid solution, and allowed to cool to room temperature to prepare an aqueous solution (second solution) containing potassium fluoride.

Thereafter, the second solution was added little by little over about 2.5 minutes to the stirred first solution, and stirred for about 10 minutes to form a pale orange solid. The solid product was filtered off and the filtered solid product was washed with a small amount of 20 wt% aqueous hydrofluoric acid. The solid product was then further washed with ethanol and dried under vacuum. As a result, Mn ^{4 +} activated K ₂ SiF ₆ phosphor powder according to Production Example R1 was obtained.

The obtained phosphor powder was subjected to powder X-ray diffraction measurement (XRD) using Cu Kα ray. As a result, all the charts obtained from the phosphor powder were able to confirm that the phosphor powder had a K ₂ SiF ₆ structure. Moreover, as a result of irradiating the said fluorescent substance powder with the light of wavelength 365nm, it has confirmed that it light-emits red.

The obtained Mn ^{4 +} activated K ₂ SiF ₆ phosphor was excited by irradiating light of 445 nm using a spectrophotometer (manufactured by Otsuka Electronics: MCPD-7000) to obtain the emission spectrum shown in FIG. 4 . Further, by monitoring the peak wavelength of this emission spectrum, an excitation spectrum was obtained.

  It can be understood from FIG. 4 that the emission spectrum of the red phosphor 16 of Production Example R1 has good wavelength matching with the red color filter 126r shown in FIG. Moreover, as a result of analyzing the emission spectrum shown in FIG. 4, the peak wavelength of the emission spectrum of the red phosphor 16 of Production Example R1 was 630 nm, and the half width was 8 nm. Moreover, when the chromaticity coordinate was calculated from the said emission spectrum, it was (CIEX, CIEy) = (0.691, 3.307) in the CIE1931 chromaticity coordinate.

<Manufacture of light emitting device 10b>
Next, Examples and Comparative Examples of the light emitting device 10b will be described with reference to FIGS. 5 and 6. FIG.

  (A)-(d) of FIG. 5 are graphs which respectively show the emission spectrum of the light-emitting device of Example DW1-DW4. In the graph of FIG. 5, the vertical axis represents emission intensity (arbitrary unit), and the horizontal axis represents wavelength (nm). Here, the emission spectrum of the comparative example RDW1 is identical to that of the examples DW1 to DW4.

  6 shows the resin frame depth, the height of the light emitting element and the shortest distance of the optical path length in the light emitting device of Example DW1 to DW4 and Comparative Example RDW1 according to Embodiment 2. FIG. The mixing ratio, the mixing ratio of the dispersing material (resin) to the total amount of phosphor, the mass productivity of the light emitting device, and the chromaticity coordinates of the white point of the white point of the light emitted from each light emitting device after passing through the liquid crystal panel It is a table showing a measurement result.

(Example DW1)
The light emitting device 10b of the example DW1 has a structure shown in (b) of FIG. The depth L of the resin frame is 1.15 mm, the height H of the light emitting element is 0.1 mm, and the value of the shortest distance (L−H) of the optical path length of blue light is 1.05. The light emitting element 11 is a blue LED (manufactured by Cree) having a light emission peak wavelength of 445 nm. The green phosphor 12 is the Mn ²⁺ -activated γ-AlON phosphor obtained in Production Example P1. The dispersing material 13 is a silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd .: KER-2500). The red phosphor 16 is the Mn ⁴⁺ activated K ₂ SiF ₆ phosphor obtained in Production Example R1.

As phosphors to be dispersed in a silicone resin, the Mn ^{4 +} activated K ₂ SiF ₆ phosphor of Production Example R 1 and the Mn ²⁺ activated γ-AlON phosphor of Production Example P 1 are mixed in a weight ratio of 1: 15.2, A body mixture was obtained.

  Next, a phosphor dispersed resin was obtained by mixing the silicone resin and the phosphor mixture at a weight ratio of 1: 1.11. Next, the obtained phosphor-dispersed resin is kneaded using a rotation and revolution mixer (manufactured by Shinky: AR-100), and the kneaded phosphor-dispersed resin is incorporated into a resin frame in a needle-like jig. The light-emitting device was obtained by using and applying manually, and hardening a silicone resin by heat processing at 150 degreeC.

  Thereafter, the obtained light emitting device was driven at a driving current of 20 mA, and the light emission spectrum was measured by a spectrophotometer (manufactured by Otsuka Electronics Co., Ltd .: MCPD-7000). As a result, the light emission spectrum shown in FIG.

In Examples DW1 to DW5 and Comparative Examples RDW1, RDW2 and RDW8, the dispersion amount of the Mn ⁴⁺ activated K ₂ SiF ₆ phosphor and the Mn ²⁺ activated γ-AlON phosphor is the light emitted from the light emitting device for the liquid crystal panel. When transmitted, the chromaticity point indicating the white point is adjusted to be white with a color temperature of 10,000 K near (CIEx, CIEy) = (0.281, 0.288). The white point is a chromaticity point on the display (on the screen) when all the light transmitted through the liquid crystal panel is displayed at the same time.

(Example DW2)
A light emitting device of Example DW2 was manufactured in the same manner as Example DW1. However, it differs from Example DW1 in the following points:
-Depth L of resin frame: 1.4 mm
· Height H of light emitting element: 0.1 mm
・ Shortest distance (L−H) of optical path length of blue light: 1.3 mm
・ Green phosphor / red phosphor weight ratio: 14.8
· Weight ratio of phosphor mixture / dispersant: 0.76
Further, in the same manner as in Example DW1, the emission spectrum shown in (b) of FIG. 5 was obtained.

(Example DW 3)
A light emitting device of Example DW3 was manufactured in the same manner as Example DW1. However, it differs from Example DW1 in the following points:
-Depth L of resin frame: 1.8 mm
· Height H of light emitting element: 0.1 mm
・ Shortest distance (L−H) of optical path length of blue light: 1.7 mm
· Weight ratio of green phosphor / red phosphor: 14.2
· Weight ratio of phosphor mixture / dispersant: 0.49
Further, in the same manner as in Example DW1, an emission spectrum shown in (c) of FIG. 5 was obtained.

(Example DW 4)
A light emitting device of Example DW4 was manufactured in the same manner as Example DW1. However, it differs from Example DW1 in the following points:
-Depth L of resin frame: 2.25 mm
· Height H of light emitting element: 0.1 mm
・ Shortest distance (L−H) of optical path length of blue light: 2.15 mm
· Weight ratio of green phosphor / red phosphor: 13.7
· Weight ratio of phosphor mixture / dispersant: 0.40
Further, in the same manner as in Example DW1, the emission spectrum shown in (d) of FIG. 5 was obtained.

(Example DW 5)
A light emitting device of Example DW5 was manufactured in the same manner as Example DW1. However, it differs from Example DW1 in the following points:
Green phosphor: Mn ²⁺ activated γ-AlON phosphor obtained in Production Example P 2 Depth of resin frame L: 1.4 mm
· Height H of light emitting element: 0.1 mm
・ Shortest distance (L−H) of optical path length of blue light: 1.3 mm
・ Weight ratio of green phosphor / red phosphor: 17.2
· Weight ratio of phosphor mixture / dispersant: 1.01
(Comparative Example RDW1)
A light emitting device of Comparative Example RDW1 was manufactured in the same manner as Example DW1. However, it differs from Example DW1 in the following points:
-Depth L of resin frame: 0.9 mm
· Height H of light emitting element: 0.1 mm
・ Shortest distance (L−H) of optical path length of blue light: 0.8 mm
· Weight ratio of green phosphor / red phosphor: 15.6
· Weight ratio of phosphor mixture / dispersant: 1.52
(Comparative Example RDW2)
A light emitting device of Comparative Example RDW2 was manufactured in the same manner as Example DW1. However, it differs from Example DW1 in the following points:
Green phosphor: Mn ²⁺ activated γ-AlON phosphor obtained in Comparative Production Example RP 1 Depth of resin frame L: 1.4 mm
· Height H of light emitting element: 0.1 mm
・ Shortest distance (L−H) of optical path length of blue light: 1.3 mm
· Weight ratio of green phosphor / red phosphor: 14.1
· Weight ratio of phosphor mixture / dispersant: 0.48
(Comparative Examples RDW3 to RDW7)
A light emitting device was produced in the same manner as in Examples DW1 to DW4 except that a commercially available Eu ²⁺ -activated β sialon phosphor (Denka company: GR series) was used as a green phosphor. The comparative examples RDW3 to RDW7 respectively have the same resin frame depth L, the height H of the light emitting element, and the shortest distance (L-H) of the optical path length of blue light as in the examples DW1 to DW4. The weight ratio of the green phosphor / red phosphor and the weight ratio of the phosphor mixture / dispersant are such that the chromaticity point indicating the white point is (CIEx, CIEy) when the light emitted from the light emitting device passes through the liquid crystal panel. The color temperature is adjusted to be white at a color temperature of 10,000 K around (0.281, 0.288).

(Comparative Example RDW 8)
A light emitting device of Comparative Example RDW8 was manufactured in the same manner as Example DW1. However, it differs from Example DW1 in the following points:
Green phosphor: Mn ²⁺ activated γ-AlON phosphor obtained in Comparative Production Example RP 2 Depth of resin frame L: 1.4 mm
· Height H of light emitting element: 0.1 mm
・ Shortest distance (L−H) of optical path length of blue light: 1.3 mm
Weight ratio of green phosphor / red phosphor: 21.6
· Weight ratio of phosphor mixture / dispersant: 1.53
<Evaluation of mass productivity of light emitting devices>
The mass productivity (yield) of the light emitting devices of Examples DW1 to DW4 and Comparative Example RDW1 was verified.

  For verification, the step of applying the phosphor-dispersed resin was carried out using a dispenser suitable for mass production of light emitting devices, not manually. Specifically, using a dispenser for mass production of light emitting devices (Musashi Engineering: SuPerΣ CMII) and a coating device (Musashi Engineering: SHOTMASTER (registered trademark) 300), phosphors are continuously dispersed for 100 light emitting devices. The resin was applied.

  As a result, in the light emitting devices of Examples DW1 to DW4 in which the shortest distance (L−H) of the optical path length of blue light is larger than 1 mm and the weight ratio of phosphor mixture / dispersion material is 1.2 or less It was possible to apply the phosphor-dispersed resin. Further, in the light emitting device 10b of Example DW1, the variation in chromaticity of light emitted from each of the manufactured 100 light emitting devices was in the range of ± 0.04 in CIEx and CIEy. Further, in the light emitting devices 10b of the examples DW2 to DW4, the variation of the chromaticity of light emitted from each of the 100 light emitting devices manufactured in each example is in the range of ± 0.02 by CIEx and CIEy. there were. This value indicates that, in the light emitting device of each example, the variation in chromaticity is small to the extent that it can be used as a practical product, and mass productivity is good.

  On the other hand, in the light emitting device of Comparative Example RDW 1 in which the shortest distance (L−H) of the optical path length of blue light is smaller than 1 mm and the weight ratio of phosphor mixture / dispersion material is 1.2, clogging of the dispenser occurs halfway It occurred, and it was not possible to perform 100 continuous application. Further, in the light emitting device of Comparative Example RDW1, the variation in chromaticity was large among the manufactured light emitting devices, and exceeded ± 0.05 in CIE y. In the light emitting device of Comparative Example RDW1, since the shortest distance of the optical path length of blue light is less than 1 mm, it is necessary to disperse a large amount of phosphor in the dispersing agent, and the flowability of the phosphor dispersed resin is significantly reduced. it is conceivable that.

  From the above results, the light emitting devices of Examples DW1 to DW4 had better yields and better mass productivity than the light emitting devices of Comparative Example RDW1. Moreover, it turned out that the weight ratio of fluorescent substance mixture / dispersing agent is 1.0 or less, and the light emitting device of Example DW2-DW4 is excellent in the mass productivity of a light emitting device especially in this case.

<Verification of the relationship between the shortest distance of the optical path length of blue light and the reduction rate of the amount of phosphors>
With regard to the light emitting devices of Examples DW1 to DW4 and Comparative Examples RDW1 and RDW3 to RDW7, the relationship between the shortest distance of the optical path length of blue light and the reduction rate of the phosphor amount was verified.

  FIG. 7 shows the shortest distance of the optical path length of blue light, the type of green phosphor, and the reduction ratio of the amount of phosphor dispersed in the dispersing material for the light emitting devices of Examples DW1 to DW4 and Comparative Examples RDW1 and RDW3 to RDW7. Is a table showing the relationship of

  In a light-emitting device in which the shortest distance of the optical path length of blue light is 0.8 mm, the chromaticity point indicating the white point is white with a color temperature of 10,000 K near (CIEx, CIE y) = (0.281, 0.288) Amount of phosphor per unit volume of the dispersing agent (the concentration of the phosphor dispersed in the dispersing agent) is 1, and the amount of the phosphor by increasing the shortest distance of the optical path length of blue light The reduction rate was calculated.

In Examples DW1 to DW4 in which the green phosphor is a Mn ²⁺ -activated γ-AlON phosphor, the amount of phosphor per unit volume of the dispersing material is significantly reduced as the shortest distance of the optical path length increases. On the other hand, in Comparative Examples RDW3 to RDW7 in which the green phosphor is an Eu ²⁺ -activated β sialon phosphor, the reduction rate of the phosphor amount was smaller.

From this, it was found that the Mn ²⁺ activated γ-AlON phosphor is more suitable for a light emitting device with a long blue light path length. This is considered to be due to the fact that the Mn ²⁺ activated γ-AlON phosphor is a forbidden transition phosphor having a lower transition probability than the Eu ²⁺ activated β sialon phosphor.

<Verification of relationship between Mn concentration and brightness and mass productivity of light emitting device>
With regard to the light emitting devices of Example DW1 and DW5 and Comparative Examples RDW2 and RDW8, the relationship between the Mn concentration in the crystal of the Mn ²⁺ activated γ-AlON phosphor and the brightness and mass productivity of the light emitting device was verified.

  FIG. 8 shows the depth of resin frame, the shortest distance between the height of the light emitting element and the optical path length, and the mixture of the green phosphor and the red phosphor in the light emitting device of Example DW2 and DW5 and Comparative Examples RDW2 and RDW8. It is a table | surface which shows a measurement result of the mixing ratio of a dispersion material (resin) and the fluorescent substance total amount, the brightness of a light-emitting device, mass productivity, and a chromaticity coordinate.

  In FIG. 8, the brightness of the light emitting device is shown as a relative value to the total luminous flux value measured for the light emitting device of Example DW2 as 100.

  Further, mass productivity was evaluated in the same manner as the method described in the above-mentioned evaluation of mass productivity. A case where the phosphor dispersed resin can be applied continuously for 100 pieces, and the variation of the chromaticity of the emitted light is in the range of ± 0.02 in CIEx and CIEy is referred to as “◎”. Similarly, a case where it is possible to apply the phosphor-dispersed resin continuously for 100 pieces, and the variation in the chromaticity of the emitted light is in the range of ± 0.04 in CIEx and CIEy, is represented as “o”. . In the case where coating was not possible in 100 continuous samples, and the variation in chromaticity was more than ± 0.05 in CIEx and CIEy, it was regarded as “x”.

As a result, Example DW2 using the Mn ²⁺ -activated γ-AlON phosphor of Production Example P1 in which the Mn concentration in the crystal is 2.4% by weight showed excellent brightness and mass productivity. Good results were also obtained for the light emitting device of Example DW5 using the Mn ²⁺ -activated γ-AlON phosphor of Production Example P2 in which the Mn concentration in the crystal is 1.81% by weight.

On the other hand, in the light emitting device of Comparative Example RDW 8 using the Mn ²⁺ activated γ-AlON phosphor of Comparative Production Example RP2 in which the Mn concentration in the crystal is 0.45% by weight, the brightness of the light emitting device decreases. In addition, the weight ratio of the phosphor mixture / dispersant is high, and it has been difficult to manufacture a light emitting device with high yield.

Third Embodiment
The present embodiment describes an image display device 100 provided with a light emitting device 10. In addition, about the member which has the same function as the member demonstrated in the above-mentioned embodiment for convenience of explanation, the same code | symbol is written in addition and the description is abbreviate | omitted.

  In the present embodiment, any of the light emitting device 10 a according to the first embodiment and the light emitting device 10 b according to the second embodiment may be used as the light emitting device 10. When the light emitting device 10 b according to the second embodiment is used, the red color filter 126 r shown in FIG. 9B may not be provided.

<Image Display Device 100>
FIG. 9A is an exploded perspective view of an image display apparatus 100 which is an example of the image display apparatus according to the present embodiment. FIG. 9B is an exploded perspective view of a liquid crystal display device 120 a included in the image display device 100 shown in FIG. 9A. FIG. 10 is a graph showing the transmission spectrum of the color filter provided in the image display device 100.

  As illustrated in (a) of FIG. 9, the image display device 100 includes a light emitting device 10, a light guide plate 110, and a liquid crystal display unit 120. The light guide plate 110 is a transparent or translucent light guide plate. The liquid crystal display unit 120 is a display unit that displays an image, and includes a plurality of liquid crystal display devices 120a.

  In the image display device 100, a plurality of light emitting devices 10 are disposed so as to face the surface of the light guide plate 110 opposite to the surface facing the liquid crystal display unit 120. In the present embodiment, as shown in FIG. 9A, a plurality of light emitting devices 10 are arranged in a matrix. Further, a liquid crystal display unit 120 configured of a plurality of liquid crystal display devices 120 a is provided adjacent to the light guide plate 110. The emitted light 130 from the light emitting device 10 is scattered in the light guide plate 110 and is irradiated to the entire surface of the liquid crystal display unit 120 as the scattered light 140.

<Liquid Crystal Display Device 120a>
As shown in (b) of FIG. 9, the liquid crystal display device 120a constituting the liquid crystal display unit 120 includes a polarizing plate 121, a transparent conductive film 123a (having a thin film transistor 122), an alignment film 124a, and a liquid crystal layer 125. An alignment film 124b, an upper thin film electrode 123b, a color filter 126 for displaying color pixels, and an upper polarizing plate 127 are sequentially laminated.

  The color filter 126 is divided into portions of a size corresponding to each pixel of the transparent conductive film 123a. The color filter 126 further includes a red color filter 126r transmitting red light, a green color filter 126g transmitting green light, and a blue color filter 126b transmitting blue light.

  The image display apparatus 100 according to the present embodiment preferably includes filters that transmit red light, green light, and blue light, as in the color filter 126 illustrated in (b) of FIG. 9. In this case, as each color filter, for example, one showing a transmission spectrum shown in FIG. 10 can be suitably used.

  As each color filter, a color filter having any transmittance generally used in an image display device can be used. In particular, as the green color filter 126g, the transmittance of light in the wavelength range of 470 nm or less is 10%. The following can be suitably used. In addition, as the green color filter 126g, one having a transmittance of 10% or less for light in a wavelength range of 600 nm to 680 nm and a half width of 90 nm or less of the transmission spectrum can be suitably used.

  Similarly, as the blue color filter 126b, one having a transmittance of 10% or less for light in a wavelength range of 520 nm or more and 680 nm or less and a half value width of 100 nm or less of the transmission spectrum can be suitably used.

  By using a color filter having such transmittance and transmission spectrum characteristics, BT. It is possible to realize an image display device that exhibits a high coverage ratio for the color gamut of 2020. Such a color filter can be manufactured by a conventionally known method, and its manufacturing method is described, for example, in Patent Document: JP-A-2015-87527.

<Example and Comparative Example of Image Display Device>
Next, an embodiment of the image display apparatus 100 and a comparative example thereof will be described with reference to FIG. FIG. 11 is a table showing the coverage, the area ratio, and the chromaticity coordinates in the image display devices of Example DIS1 and DIS2 according to the present embodiment and Comparative Example RDIS1.

(Example DIS1)
The image display apparatus of the embodiment DIS1 is an image display apparatus 100 having a structure shown in FIG. In the image display apparatus 100 of the embodiment DIS1, the light emitting device 10b of the embodiment DW2 was used as a backlight. Moreover, in the image display apparatus 100 of Example DIS1, as a color filter, what has the transmittance | permeability shown in FIG. 10 was used. That is, the color filter 126 including the red color filter 126r, the green color filter 126g, and the blue color filter 126b is used.

(Example DIS2)
An image display device of Example DIS2 was manufactured in the same manner as Example DIS1 except that the light emitting device 10b of Example DW5 was used as a backlight.

(Comparative example RDIS1)
An image display device of Comparative Example RDIS1 was manufactured in the same manner as Example DIS1 except that the light emitting device 10b of Comparative Example RDW2 was used as a backlight.

(Evaluation of each image display device)
The color coordinates of red point, green point and blue point in CIE 1931 chromaticity coordinates of display light on the display (on the screen) in the image display apparatus of the above-mentioned example DIS1 and DIS2 and comparative example RDIS1; The 2020 cover ratio and the area ratio are shown in FIG.

  Here, the red point, the green point, and the blue point are chromaticity points on the display when only light passing through the red color filter, the green color filter, and the blue color filter is displayed on the display. BT. The 2020 cover rate is BT. It is a ratio of the area covered by the color gamut surrounded by the red point, the green point and the blue point to the area of the color gamut of 2020. BT. The 2020 area ratio is BT. It is a ratio of the area of the color gamut surrounded by the red point, the green point, and the blue point to the area of the color gamut of 2020.

  In addition, the chromaticity point shown in FIG. 2020 cover rate and BT. The 2020 area ratio was calculated from the spectrum data measured using Otsuka Electronics MCPD-7000.

  As shown in FIG. 11, the image display devices of the embodiments DIS1 and DIS2 are BT. For the 2020 color gamut, it has a high coverage ratio and area ratio of 80% or more, and has a color gamut suitable as a next generation wide color gamut display. Thus, the light emitting devices of Example DW2 and Example DW5 not only have excellent luminous efficiency and mass productivity, but also realize an image display device having high color reproducibility.

On the other hand, the image display device of the comparative example RDIS1 is BT. The 2020 coverage rate was below 80%. It is presumed that this is because the color gamut of the image display device is narrowed because the Mn concentration in the crystal of the Mn ²⁺ activated γ-AlON phosphor used in the light emitting device of Comparative Example RDW 2 is too high.

  Note that the color reproduction range of the image display device is practically influenced by the numerical value of the coverage rate more than the area ratio. That is, the image display apparatus is BT. In order to actually improve the color reproduction range of the image display device when used as a display device conforming to the plan of 2020, BT. It is important to improve the coverage for the 2020 color gamut.

[Summary]
A light emitting device (10) according to aspect 1 of the present disclosure includes: a light emitting element (11) that emits blue light; an Mn ²⁺ activated γ-AlON phosphor (12) that is excited by the blue light to emit green light; dispersing agent for dispersing the Mn ²⁺ activated gamma-AlON phosphor (13), comprising a concentration of the ^{Mn 2+} activated gamma-AlON Mn contained in the phosphor crystals is less than 1 wt% or more and 3 wt% The shortest distance of the optical path length of the blue light formed when transmitting the dispersion material is greater than 1 mm and 5 mm or less.

  According to the above configuration, it is possible to realize a light emitting device in which a wide color gamut and high mass productivity are compatible. As a result, by using the light emitting device, an image display device in which a wide color gamut and high mass productivity are compatible can be realized.

In the light emitting device according to aspect 2 of the present disclosure, in the above aspect 1, the average particle diameter of the Mn ²⁺ -activated γ-AlON phosphor is preferably 5 μm or more and 40 μm or less.

  According to the above configuration, it is possible to prevent a decrease in the yield of the light-emitting device according to one embodiment of the present disclosure and to ensure mass productivity.

  The light emitting device according to aspect 3 of the present disclosure preferably further includes a red phosphor (16) which is excited by the blue light to emit red light.

  According to the above configuration, it is possible to improve the color reproducibility of the image display device provided with the light emitting device according to one aspect of the present disclosure.

In the light emitting device according to aspect 4 of the present disclosure, in the above aspect 3, the ratio of the total weight of the Mn ²⁺ -activated γ-AlON phosphor and the red phosphor to the weight of the dispersing material is 1.2 or less Is preferred.

  According to the above configuration, a decrease in yield can be prevented more reliably, and mass productivity can be further enhanced.

  In the light emitting device according to aspect 5 of the present disclosure, in any one of the aspects 1 to 4, the peak wavelength of the blue light is preferably 440 nm or more and 460 nm or less.

According to the above configuration, the excitation efficiency of the Mn ²⁺ -activated γ-AlON phosphor and the red phosphor can be enhanced. In addition, the wavelength matching with the blue color filter that transmits blue light is good. Therefore, the light emission efficiency of the light emitting device can be improved. In addition, the luminance (display brightness) of the image display device including the light emitting device can be improved.

  It is preferable that the image display apparatus (100) which concerns on aspect 6 of this indication is provided with the light-emitting device which concerns on any one of the said aspect 1-5.

  According to the above configuration, the same effects as the light emitting device according to one aspect of the present disclosure are obtained.

[Items to be added]
One aspect of the present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the technical means disclosed in the different embodiments can be combined as appropriate. These embodiments are also included in the technical scope of one aspect of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

DESCRIPTION OF SYMBOLS 10, 10a, 10b Light-emitting device 11 Light-emitting element 12 Mn ²⁺ activated gamma-AlON fluorescent substance 13 Dispersion material 16 Red fluorescent substance 100 Image display apparatus

Claims (6)

A light emitting element that emits blue light;
An Mn ²⁺ -activated γ-AlON phosphor that emits green light when excited by the blue light;
A dispersing agent for dispersing the Mn ²⁺ -activated γ-AlON phosphor,
The concentration of Mn contained in the crystal of the Mn ²⁺ activated γ-AlON phosphor is 1 wt% or more and less than 3 wt%,
A light emitting device, wherein a shortest distance of an optical path length of the blue light formed when transmitting the dispersion material is larger than 1 mm and 5 mm or less. The light emitting device according to claim 1, wherein an average particle diameter of the Mn ²⁺ activated γ-AlON phosphor is 5 μm or more and 40 μm or less.   The light emitting device according to claim 1, further comprising a red phosphor that is excited by the blue light to emit red light. The light emitting device according to claim 3, wherein a ratio of a total weight of the Mn ²⁺ -activated γ-AlON phosphor and the red phosphor to the weight of the dispersing material is 1.2 or less.   The peak wavelength of the said blue light is 440 nm or more and 460 nm or less, The light-emitting device of any one of Claims 1-4 characterized by the above-mentioned.   An image display apparatus comprising the light emitting device according to any one of claims 1 to 5.

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