JP2018018931A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce high-energy light of 435nm or less in wavelength while suppressing the reduction in light emission intensity.SOLUTION: A light-emitting device comprises: a light-emitting element having light emission peak wavelength in a range of 420 to 470 nm; and a fluorescent member including a first phosphor having a light emission peak wavelength in a range of 450-470 nm, of which the relative reflectance is 55% or less to a reflectance of calcium hydrogen phosphate in a range of 380-435 nm.SELECTED DRAWING: Figure 7B

Description

  The present disclosure relates to a light emitting device.

  As a light emitting device using a light emitting element such as a light emitting diode (hereinafter referred to as “LED”), a white light emitting device using a blue light emitting element and a yellow light emitting phosphor is well known. It has been. Such light emitting devices are used in a wide range of fields such as general lighting, in-vehicle lighting, displays, and backlights for liquid crystals. As a light-emitting device that emits monochromatic blue light, a light-emitting device including a light-emitting element with an emission wavelength of 390 to 420 nm and a blue-emitting phosphor with a wavelength of 410 to 480 nm has been proposed (see, for example, Patent Document 1).

JP 2002-171000 A

  In recent years, there is a concern that, for example, short-wavelength light emitted from such a light-emitting device, particularly high-energy light having a wavelength of 435 nm or less, adversely affects human eyes. When a color filter is used as a method for reducing such high-energy light, the light emission intensity of the light-emitting device also decreases because the light emission intensity in the blue region decreases. On the other hand, in a method of manufacturing a light emitting device, a method of selecting a light emitting element having a long emission peak wavelength is not practical because the emission peak wavelength is out of a desired range.

  Therefore, an embodiment according to the present disclosure aims to provide a light emitting device capable of reducing high energy light having a wavelength of 435 nm or less while suppressing a decrease in light emission intensity.

  The first aspect according to the present disclosure is a light emitting device having an emission peak wavelength in a range of 420 nm or more and 470 nm or less, and a relative reflectance with respect to a reflectance of calcium hydrogen phosphate in a range of 380 nm or more and 435 nm or less is 55% or less, And a fluorescent member including a first phosphor having an emission peak wavelength in a range of 450 nm to 470 nm.

  According to an embodiment of the present disclosure, it is possible to provide a light emitting device capable of reducing high energy light having a wavelength of 435 nm or less while suppressing a decrease in light emission intensity.

It is a schematic sectional drawing which shows an example of the light-emitting device which concerns on this embodiment. It is a schematic sectional drawing which shows another example of the light-emitting device which concerns on this embodiment. It is a figure which shows an example of the emission spectrum which shows the relative light emission intensity with respect to the wavelength of 1st fluorescent substance. It is a figure which shows an example of the spectral reflectance with respect to the wavelength of a 1st fluorescent substance. It is a figure which shows the emission spectrum which shows the relative light emission intensity with respect to the wavelength of the light-emitting device obtained by Comparative Examples 1-3. It is a figure which shows the emission spectrum which shows the relative light emission intensity with respect to the wavelength of the light-emitting device obtained in Example 1-3. It is a figure which shows the emission spectrum which shows the relative light emission intensity with respect to the wavelength of the light-emitting device obtained in Example 4-6. It is a figure which shows the emission spectrum which shows the relative light emission intensity with respect to the wavelength of the light-emitting device obtained in Example 7 and 8. It is a figure which shows the emission spectrum which shows the relative light emission intensity with respect to the wavelength after the color filter permeation | transmission of the light-emitting device obtained by the comparative example 4 and Example 9 and 12. It is the elements on larger scale of FIG. 6A. It is a figure which shows the emission spectrum which shows the relative light emission intensity with respect to the wavelength after the color filter permeation | transmission of the light-emitting device obtained by the comparative example 5, Example 10, 13 and 15. It is the elements on larger scale of FIG. 7A. It is a figure which shows the emission spectrum which shows the relative light emission intensity with respect to the wavelength after the color filter permeation | transmission of the light-emitting device obtained by the comparative example 6, Example 11, 14, and 16. FIG. It is the elements on larger scale of FIG. 8A.

  Hereinafter, a light-emitting device according to the present disclosure will be described based on embodiments. However, the embodiment described below exemplifies a light emitting device for embodying the technical idea of the present invention, and the present invention does not specify the light emitting device as follows. The relationship between the color name and the chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, and the like comply with JIS Z8110. In the present specification, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. means. The average particle diameter is a numerical value called Fisher Sub Sieve Sizer's No., and is measured using an air permeation method. The full width at half maximum of the phosphor means the wavelength width of the emission spectrum showing the emission intensity of 50% of the maximum emission intensity in the emission spectrum.

The light emitting device 100 according to the present embodiment will be described in detail with reference to FIG. The light emitting device 100 is an example of a surface mount type light emitting device.
The light emitting device 100 emits light on the short wavelength side of visible light (for example, a range of 380 nm to 485 nm), and the light emitting device 10 of a gallium nitride compound semiconductor having an emission peak wavelength in a range of 420 nm to 470 nm, And a molded body 40 on which the light emitting element 10 is disposed. The molded body 40 is formed by integrally molding the first lead 20 and the second lead 30 and the resin portion 42. The molded body 40 forms a recess having a bottom surface and side surfaces, and the light emitting element 10 is disposed on the bottom surface of the recess. The light emitting element 10 has a pair of positive and negative electrodes, and the pair of positive and negative electrodes are electrically connected to the first lead 20 and the second lead 30 through wires 60, respectively. The light emitting element 10 is covered with a fluorescent member 50. The fluorescent member 50 includes, for example, a phosphor 71 (first phosphor) that converts the wavelength of light from the light emitting element 10 and a resin.

  In the light emitting device 200 shown in FIG. 2, the fluorescent member 50 includes, as the phosphor 70, at least three kinds of phosphors of a first phosphor 71, a second phosphor 72, and a third phosphor 73 and a resin.

  The first phosphor 71 has a relative reflectance of 55% or less with respect to the reflectance of calcium hydrogen phosphate in the range of 380 nm to 435 nm, and has an emission peak wavelength in the range of 450 nm to 470 nm. The light emitting device 100 is configured by combining the light emitting element 10 having the specific emission peak wavelength with the fluorescent member 50 including the first phosphor 71 having the specific reflectance and the emission peak wavelength, thereby suppressing a decrease in emission intensity. However, it becomes possible to reduce high energy light having a wavelength of 435 nm or less.

Light emitting element 10
The light emission peak wavelength of the light emitting element 10 is in the range of 420 nm or more and 470 nm or less, and is preferably in the range of 430 nm or more and 460 nm or less from the viewpoint of light emission efficiency and the color tone of the entire light emitting device to be finally obtained. By using a part of the light of the light emitting element 10 having the emission peak wavelength in this range as the excitation light of the phosphor 70, a part of the light of the light emitting element 10 is effectively used as a part of the light emitted to the outside. Therefore, a highly efficient light-emitting device can be obtained. Furthermore, since the emission peak wavelength is on the longer wave side than the near-ultraviolet region and there are few ultraviolet components, the safety as a light source is excellent.

The half width of the emission spectrum of the light emitting element 10 can be set to 30 nm or less, for example.
The light emitting element 10 is preferably a semiconductor light emitting element such as an LED. As an excitation light source, for example, nitride semiconductor _{(In X Al Y Ga 1-} X-Y N, where X and Y, 0 ≦ X, 0 ≦ Y, X + satisfy Y ≦ 1) semiconductor light emitting device using By using this, it is possible to obtain a stable light-emitting device that is highly efficient, has high output linearity with respect to input, and is resistant to mechanical shock.

Fluorescent member 50
The fluorescent member 50 includes at least one first phosphor 71 that absorbs light emitted from the light emitting element 10 and emits blue light, and may include other phosphors, resins, and the like as necessary. When the fluorescent member 50 includes the first phosphor 71, at least a part of the high energy light having a wavelength of 435 nm or less is absorbed among the light emitted from the light emitting element 10. For example, the light from the light emitting element 10 and the fluorescence from the first phosphor 71 overlap in the range of 450 nm to 470 nm to form light having a single light emission peak wavelength, thereby reducing the light emission intensity. Thus, it is possible to configure the light emitting device 100 having an emission spectrum in which high energy light having a short wavelength of 435 nm or less is reduced.

First phosphor 71
The first phosphor 71 has a relative reflectance of 55% or less, preferably 45% or less, more preferably 40% or less, with respect to the reflectance of calcium hydrogen phosphate in the range of 380 nm to 435 nm. When the relative reflectance is 55% or less, a light-emitting device in which at least part of high-energy light having a wavelength of 435 nm or less is absorbed and adverse effects on the human body are reduced can be obtained. Here, the relative reflectance of the first phosphor 71 is the first when the spectral reflectance at each wavelength of 380 nm to 435 nm of calcium hydrogen phosphate (CaHPO ₄ , average particle size 2.7 μm) is 100%. It is measured as the spectral reflectance of the phosphor 71. The relative reflectance being 55% or less means that the maximum value of the relative reflectance in the range of 380 nm to 435 nm is 55% or less.

  The emission peak wavelength of the first phosphor 71 is in the range of 450 nm to 470 nm, and preferably in the range of 455 nm to 465 nm. The full width at half maximum in the emission spectrum of the first phosphor 71 is, for example, 20 nm to 60 nm, and preferably 20 nm to 50 nm.

  Further, by positioning the emission peak wavelength of the first phosphor 71 in the vicinity of the emission peak wavelength of the light emitting element 10, a light emitting device having an emission spectrum having a single emission peak can be configured. In order to narrow the half width of the single emission peak wavelength, the difference between the emission peak wavelength of the first phosphor 71 and the emission peak wavelength of the light emitting element 10 is, for example, 30 nm or less, preferably 20 nm or less. be able to. In this case, the first phosphor 71 can be used as a phosphor excitation light source in the same manner as the light emitting element 10.

The first phosphor 71 preferably has, for example, a composition represented by the formula (I) from the viewpoint of maintaining emission intensity and reducing high energy light having a wavelength of 435 nm or less, and is represented by the formula (Ia) or (Ib). It is more preferable to have a composition.
(I) (Ca, Sr, Ba, Mg) ₁₀ (PO ₄ ) ₆ (F, Cl, Br, I, OH) ₂ : Eu
(Ia) Ca ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu
(Ib) Ca ₁₀ (PO ₄ ) ₆ (Cl, Br) ₂ : Eu

  The average particle diameter of the first phosphor 71 is, for example, 3 μm or more and 40 μm or less, and preferably 5 μm or more and 30 μm or less. The emission intensity can be increased by setting the average particle size to a predetermined value or more. By setting the average particle size to a predetermined value or less, workability in the manufacturing process of the light emitting device can be improved.

  The content rate of the 1st fluorescent substance 71 in the fluorescent member 50 is 1 mass% or more with respect to resin contained in the fluorescent member 50, for example, and 5 mass% or more is preferable. Moreover, the content rate of the 1st fluorescent substance 71 is 40 mass% or less with respect to resin which the fluorescent member 50 contains, for example, and 35 mass% or less is preferable. By setting the content of the first phosphor 71 in the fluorescent member 50 within the above range, the light emitting device 100 having an emission spectrum in which high energy light having a wavelength of 435 nm or less is reduced while maintaining the light emission intensity of the light emitting device. Can be configured.

  Since the light emitting device 100 includes the fluorescent member 50 including the first phosphor 71, high energy light having a wavelength of 435 nm or less emitted from the light emitting device 100 is reduced. The reduction rate of high energy light having a wavelength of 435 nm or less in the light emitting device 100 is, for example, 10% or more, and preferably 20% or more. Here, the reduction rate of the high energy light having a wavelength of 435 nm or less is not provided with the fluorescent member 50 including the first phosphor 71 while having the same light emitting element 10 for the integrated value of the emission intensity in the range of 380 nm to 435 nm. The light emitting device is used as a reference (reduction rate 0%), and details will be described later in the embodiment, but the calculation is based on an integral value corrected with a radiant flux measured by an integrating sphere.

Second phosphor 72
The fluorescent member 50 may include a second phosphor 72 in addition to the first phosphor 71. When the fluorescent member 50 includes the second phosphor 72, a light emitting device that emits a mixed color of light emitted from the light emitting element 10, the first phosphor 71, and the second phosphor 72 can be configured. The second phosphor 72 has an emission peak wavelength in the range of 500 nm to 600 nm, and preferably in the range of 510 nm to 580 nm. The half width in the emission spectrum of the second phosphor 72 is, for example, not less than 20 nm and not more than 130 nm. The second phosphor 72 preferably has an emission peak wavelength in the range of 510 nm to 550 nm and a half width of 20 nm to 80 nm.

The second phosphor 72 preferably includes at least one phosphor having a composition represented by any of the following formulas (IIa), (IIb), (IIc) and (IId), for example. Among these, for example, when applied to an image display device, the range of the color reproducibility of the light emitting device is expanded, and in the formula (IIa), (IIc) or (IId) having an emission spectrum with a relatively narrow half width. More preferably, it comprises at least one phosphor having the composition represented. In addition, by including at least one phosphor having a composition represented by the formula (IIb), a light emitting device having good light emission efficiency can be configured.
_{(IIa) Si 6-z Al} z O z N 8-z: Eu (0 <z ≦ 4.2)
_{(IIb) Ln 3 Al 5-} p Ga p O 12: Ce
In the formula (IIb), Ln is at least one selected from the group consisting of Y, Lu, Gd and Tb, and p satisfies 0 ≦ p ≦ 3.
(IIc) (Sr _1-xy , M ¹ _y , Eu _x ) Ga ₂ S ₄
In formula (IIc), M ¹ represents at least one element selected from the group consisting of Be, Mg, Ca, Ba, and Zn, and x and y are 0.03 ≦ x ≦ 0.25, 0 ≦ Satisfy y <0.97 and x + y <1.
(IId) M ¹¹ ₈ MgSi ₄ O ₁₆ X ₂ : Eu
In formula (IId), M ¹¹ is at least one selected from the group consisting of Ca, Sr, Ba and Zn, and X is at least one selected from the group consisting of F, Cl, Br and I It is.

  The average particle diameter of the second phosphor 72 is, for example, 1 μm or more and 40 μm or less, and preferably 5 μm or more and 30 μm or less. The emission intensity can be increased by setting the average particle size to a predetermined value or more. By setting the average particle size to a predetermined value or less, workability in the manufacturing process of the light emitting device can be improved.

  When the fluorescent member 50 includes the second fluorescent material 72, the content rate of the second fluorescent material 72 is, for example, 5% by mass or more with respect to the resin included in the fluorescent member 50, and preferably 10% by mass or higher. Moreover, the content rate of the 2nd fluorescent substance 72 is 90 mass% or less with respect to resin contained in the fluorescent member 72, for example, and 80 mass% or less is preferable.

Third phosphor 73
The fluorescent member 50 may include a third phosphor 73 in addition to the first phosphor 71 and the second phosphor 72. When the light emitting device 200 in which the fluorescent member 50 includes the first phosphor 71, the second phosphor 72, and the third phosphor 73 is applied to, for example, an image display device, a wider color reproduction range can be achieved. The third phosphor 73 has an emission peak wavelength in the range of 620 nm to 670 nm, and preferably in the range of 625 nm to 660 nm. The half width in the emission spectrum of the third phosphor 73 is, for example, 5 nm to 100 nm, and preferably 5 nm to 30 nm.

The third phosphor 73 preferably includes at least one phosphor having a composition represented by any of the following formulas (IIIa) to (IIIf), for example. Among these, in order to expand the color reproducibility range of the light emitting device, it has an emission spectrum having a relatively narrow half width, and has a composition represented by (IIIa), (IIIb), (IIId) or (IIIf) It is preferable to include at least one phosphor.
(IIIa) A ₂ [M _1-a Mn _a F ₆ ]
In formula (IIIa), A represents at least one selected from the group consisting of alkali metals and ammonium, and M represents at least one selected from the group consisting of Group 4 elements and Group 14 elements. , A satisfies 0.01 <a <0.2.
(IIIb) (i-j) MgO. (J / 2) Sc ₂ O ₃ .kMgF ₂ .mCaF _2. (1-n) GeO _2. (N / 2) M ^t ₂ O ₃ : zMn
In formula (IIIb), M ^t is at least one selected from the group consisting of Al, Ga and In, and i, j, k, m, n and z are 2 ≦ i ≦ 4 and 0 <k, respectively. <1.5, 0 <z <0.05, 0 ≦ j <0.5, 0 <n <0.5, and 0 ≦ m <1.5.
_{(IIIc) (Ca 1-p} -q Sr p Eu q) AlSiN 3
In formula (IIIc), p and q are numbers satisfying 0 ≦ p ≦ 1.0, 0 <q <1.0 and p + q <1.0.
^{_{(IIId) M a v M b}} w M c x Al 3-y Si y N z
In formula (IIId), M ^a is at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and M ^b is at least one selected from the group consisting of Li, Na and K And M ^c is at least one element selected from the group consisting of Eu, Ce, Tb and Mn, and v, w, x, y and z are each 0.80 ≦ v ≦ 1.05, 0.80 ≦ w ≦ 1.05, 0.001 <x ≦ 0.1, 0 ≦ y ≦ 0.5, 3.0 ≦ z ≦ 5.0.
_{(IIIe) (Ca 1-r} -s-t Sr r Ba s Eu t) 2 Si 5 N 8
In formula (IIIe), r, s, and t are numbers that satisfy 0 ≦ r ≦ 1.0, 0 ≦ s ≦ 1.0, 0 <t <1.0, and r + s + t ≦ 1.0.
(IIIf) (Ca, Sr) S: Eu

  The average particle diameter of the third phosphor 73 is, for example, 1 μm or more and 40 μm or less, and preferably 5 μm or more and 30 μm or less. The emission intensity can be increased by setting the average particle size to a predetermined value or more. By setting the average particle size to a predetermined value or less, workability in the manufacturing process of the light emitting device can be improved.

  When the fluorescent member 50 includes the third fluorescent material 73, the content of the third fluorescent material 73 is, for example, 5% by mass or more with respect to the resin included in the fluorescent member 50, and preferably 10% by mass or higher. Moreover, the content rate of the 3rd fluorescent substance 73 is 90 mass% or less with respect to resin contained in the fluorescent member 50, for example, and 80 mass% or less is preferable.

Resin The fluorescent member 50 can include at least one resin in addition to the phosphor 70. The resin may be either a thermoplastic resin or a thermosetting resin. Specific examples of the thermosetting resin include an epoxy resin and a silicone resin.

Other Components The fluorescent member 50 may include other components as needed in addition to the first phosphor 71 and the resin. Examples of other components include fillers such as silica, barium titanate, titanium oxide, and aluminum oxide, light stabilizers, and colorants. For example, when a fluorescent member contains a filler as another component, the content can be 0.01 mass% to 20 mass% with respect to resin.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

As the first phosphor 71, two types of halophosphate phosphors having the following compositions were prepared.
Ca ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu (hereinafter also referred to as “CCA”)
Ca ₁₀ (PO ₄ ) ₆ (Cl, Br) ₂ : Eu (hereinafter also referred to as “CBA”)

FIG. 3 shows emission spectra of CCA and CBA. In FIG. 3, the emission spectrum with respect to the wavelength of the relative light emission intensity when each maximum light emission intensity is set to 1 is shown. FIG. 4 shows the spectral reflectance of CCA and CBA. FIG. 4 shows the relative reflectance when the reflectance of calcium hydrogen phosphate (CaHPO ₄ , average particle diameter of 2.7 μm) at each wavelength is 100% with respect to the wavelength. The maximum relative reflectance of the first phosphor 71 in the range of 380 nm to 435 nm was 33% CCA and 43% CBA as values at 435 nm, both of which were 55% or less.

  3 that CCA and CBA have an emission peak wavelength in the vicinity of 460 nm. Further, FIG. 4 shows that CCA has a lower reflectance than CBA in the range of 380 nm to 480 nm, that is, CCA absorbs more light from the light emitting element than CBA in this wavelength region. .

Example 1
A silicone resin and 10% by mass of CCA with respect to the silicone resin were mixed and dispersed, and then defoamed to obtain a phosphor-containing resin composition. Next, a molded body 40 having a recess is prepared, and after the light emitting element 10 having an emission peak wavelength of 443 nm is disposed on the bottom surface of the recess, a phosphor-containing resin composition is injected and filled on the light emitting element 10. Furthermore, the resin composition was hardened by heating. The light emitting device 100 was manufactured through such steps.

(Example 2)
A light emitting device 100 was manufactured in the same manner as in Example 1 except that the light emitting element 10 was changed to a light emitting element having an emission peak wavelength of 447 nm.

(Example 3)
A light emitting device 100 was manufactured in the same manner as in Example 1 except that the light emitting element 10 was changed to a light emitting element having an emission peak wavelength of 455 nm.

Example 4
A light emitting device 100 was produced in the same manner as in Example 1 except that 30% by mass of CCA was used with respect to the silicone resin.

(Example 5)
A light emitting device 100 was produced in the same manner as in Example 2 except that 30% by mass of CCA was used with respect to the silicone resin.

(Example 6)
A light emitting device 100 was produced in the same manner as in Example 3 except that 30% by mass of CCA was used with respect to the silicone resin.

(Example 7)
A light emitting device 100 was manufactured in the same manner as in Example 5 except that CBA was used instead of CCA.

(Example 8)
A light emitting device 100 was fabricated in the same manner as in Example 6 except that CBA was used instead of CCA.

(Comparative Example 1)
A light emitting device was produced in the same manner as in Example 1 except that CCA was not blended and only the silicone resin was injected into the recess.

(Comparative Example 2)
A light emitting device was fabricated in the same manner as in Comparative Example 1 except that the light emitting element 10 was changed to a light emitting element having an emission peak wavelength of 447 nm.

(Comparative Example 3)
A light emitting device was manufactured in the same manner as in Comparative Example 1 except that the light emitting element 10 was changed to a light emitting element having an emission peak wavelength of 455 nm.

  Table 1 below shows configurations of Examples 1 to 8 and Comparative Examples 1 to 3. FIG. 5A shows an emission spectrum showing the relative emission intensity with respect to the wavelength of the light emitting devices obtained in Comparative Examples 1 to 3. FIG. 5B shows an emission spectrum showing the relative emission intensity with respect to the wavelength of the light emitting device 100 obtained in Examples 1 to 3. FIG. 5C shows an emission spectrum showing the relative emission intensity with respect to the wavelength of the light emitting device 100 obtained in Examples 4 to 6. FIG. 5D shows emission spectra indicating relative emission intensities with respect to wavelengths of the light emitting devices 100 obtained in Examples 7 and 8, respectively. The emission spectra shown in FIGS. 5A to 5D are relatively drawn with the emission intensity at the emission peak wavelength of Comparative Example 1 shown in FIG. 5A as a reference (100%). As shown in FIGS. 5B to 5D, the emission spectra of the light emitting devices 100 of Examples 1 to 8 have a single emission peak. It can also be seen that the emission peak wavelength in the emission spectrum of the light emitting device 100 becomes longer as the emission peak wavelength of the light emitting element 10 becomes longer.

  With respect to the light emitting devices 100 obtained in Examples 1 to 8 and the light emitting devices obtained in Comparative Examples 1 to 3, the radiant flux was measured using an integrating sphere, and the radiation of each comparative example was classified according to the emission peak wavelength of the light emitting element 10. The radiant flux of the light emitting device 100 according to the example was calculated as a relative value (%) with the bundle as 100%. The emission intensity reduction rate of 435 nm or less was calculated from the radiant flux and emission spectrum as follows. The results are summarized in Tables 2 to 4 for each of emission peak wavelengths 443 nm, 447 nm, and 455 nm of the light emitting device 10.

For each emission peak wavelength of the light-emitting element 10, a coefficient that makes the radiant flux of the light-emitting device 100 of the example equal to the radiant flux of the comparative example was obtained based on the comparative example. In the range of 380 nm or more and 435 nm or less, the integral value of the emission intensity multiplied by the previously obtained coefficient was calculated. Using the integrated value of the light emitting device of the comparative example as a reference (0%), the emission intensity reduction rate of 435 nm or less in the light emitting device 100 of the example was calculated by the following formula.
Reduction rate of emission intensity below 435nm (%)
= {1- (Integral value of Example / Integral value of Comparative Example)} × 100

  In the light emitting device 100 obtained in Examples 1 to 8, the emission peak wavelengths of 443 nm, 447 nm, and 455 nm of the light emitting element 10 are in the range of 435 nm or less as compared with the light emitting devices obtained in Comparative Examples 1 to 3, respectively. The emission intensity is reduced by 20% or more. At this time, the radiant flux is maintained at 90% or more. Specifically, for example, in Example 1 where the emission peak wavelength of the light-emitting element 10 is 443 nm, which is a relatively short wavelength, the content of the first phosphor (CCA) 71 is 10% by mass with respect to the silicone resin. The emission intensity reduction rate of 435 nm or less with respect to Comparative Example 1 is 24%, but the radiant flux is maintained at 99%. In Example 4, the CCA content was 30% by mass with respect to the silicone resin, and the emission intensity reduction rate of 435 nm or less reached 48%, while the radiant flux maintained 94%.

  As can be seen from the evaluation results of Examples 2 and 5, and Examples 3 and 6, the emission intensity reduction rate of 435 nm or less decreases as the emission peak wavelength of the light-emitting element 10 increases. For example, when the content of the first phosphor 71 (CCA) is 10% by mass with respect to the resin, in Example 1 where the emission peak wavelength of the light emitting element 10 is 443 nm, the emission intensity reduction rate is 24%. In Example 3 where the emission peak wavelength of the light emitting element 10 is 455 nm, the emission intensity reduction rate is as low as 20%. This is presumably because the spectral reflectance of CCA or CBA, which is the first phosphor 71, increases as the wavelength increases in the blue region, that is, it becomes difficult to absorb the light emitted from the light emitting element 10.

  The first phosphor 71 used in Examples 7 and 8 is CBA having a higher reflectance in the blue region than CCA, and the emission intensity reduction rates in Examples 7 and 8 are 45% and 31%, respectively. Compared with 46% and 37% of the emission intensity reduction rates of Examples 5 and 6 in which the first phosphor 71 is CCA, the emission intensity reduction rate is slightly smaller. This is probably because CBA has a higher reflectance than CCA in the blue region of the light emission wavelength region of light emitting element 10, that is, CBA is less likely to absorb light emitted from the light emitting element than CCA.

Example 9
CCA as the first phosphor 71 is 10% by mass with respect to the silicone resin, β-sialon phosphor represented by the formula (IIa) is 27% by mass as the second phosphor 72, and the formula (IIIa) is as the third phosphor 73. After mixing and dispersing phosphor 70 blended so that the chromaticity coordinates are about x = 0.300 and y = 0.290 using 73% by mass of the KSF phosphor represented by The phosphor-containing resin composition was obtained by defoaming. Next, a compact 40 having a recess is prepared, and a light emitting element having an emission peak wavelength of 443 nm is disposed on the bottom surface of the recess, and then a phosphor-containing resin composition is injected and filled onto the light emitting element 10. The resin composition was cured by heating. The light emitting device 200 was manufactured through such a process.

(Examples 10 to 16)
The type of the first phosphor 71 and the content ratio with respect to the resin were changed as shown in Tables 5 to 7 below, and the emission peak wavelength of the light-emitting element 10 was changed to 447 nm in Examples 10, 13, and 15. 11, 14 and 16 were changed to 455 nm, and the content ratio of the second phosphor 72 and the third phosphor 73 with respect to the resin was such that the chromaticity coordinates were near x = 0.300 and y = 0.290. A light emitting device 200 was fabricated in the same manner as in Example 9 except that the change was made.

(Comparative Examples 4 to 6)
A light emitting device was produced in the same manner as in Example 9 except that the first phosphor 71 was not used. However, in Comparative Example 5, the emission peak wavelength of the light-emitting element 10 was changed to 447 nm, and in Comparative Example 6, it was changed to 455 nm.

  For the light emitting devices 200 obtained in Examples 9 to 16 and the light emitting devices obtained in Comparative Examples 4 to 6, the light emission characteristics after passing through any color filter, the NTSC content ratio (%), and the DCI coverage ( %) Was obtained by simulation. The relative luminance was calculated for each emission peak wavelength of the light emitting element 10 with the luminance of the light emitting device of the comparative example as a reference (100%). Further, the emission intensity reduction rate of 435 nm or less was calculated in the same manner as described above except that the correction was made with the relative luminance instead of the radiant flux. The results are shown in Tables 5 to 7.

  FIG. 6A shows an emission spectrum showing the relative emission intensity with respect to the wavelength after passing through the color filter of the light emitting device obtained in Comparative Example 4 and the light emitting device 200 obtained in Examples 9 and 12, and FIG. 6B shows a partially enlarged view thereof. Indicates. FIG. 7A shows an emission spectrum showing the relative emission intensity with respect to the wavelength after passing through the color filter of the light emitting device obtained in Comparative Example 5 and the light emitting device 200 obtained in Examples 10, 13 and 15, and FIG. An enlarged view is shown. FIG. 8A shows an emission spectrum showing the relative emission intensity with respect to the wavelength after passing through the color filter of the light emitting device obtained in Comparative Example 6 and the light emitting device 200 obtained in Examples 11, 14 and 16, and FIG. An enlarged view is shown.

  When the light emission element 10 has the shortest emission peak wavelength of 443 nm, in Example 12 in which the content of CCA as the first phosphor 71 is 30% by mass with respect to the silicone resin, the emission intensity reduction rate of 435 nm or less is 40%. %, And the relative luminance ratio is 93%. Regarding the NTSC ratio and DCI coverage for evaluating the color reproduction range, the NTSC ratios of Example 12 and Comparative Example 4 are 86.4% and 87.3%, respectively, and the DCI coverage is the same as 85.5%, respectively. It is a value and is in the same color reproduction range. Thus, in the light emitting device 200 of Example 12, the light emission intensity of 435 nm or less is reduced by 40% without reducing the numerical value of the color reproduction range. The relative luminance is maintained at 90% or higher.

  When the light emission element 10 has the longest emission peak wavelength of 455 nm, in Example 14 in which the CCA content of the first phosphor 71 is 30% by mass with respect to the silicone resin, the emission intensity reduction rate of 435 nm or less is 36%. And the relative luminance is 95%. Regarding the NTSC ratio and DCI coverage for evaluating the color reproduction range, the NTSC ratios of Example 14 and Comparative Example 6 are 83.5% and 84.0%, respectively, and the DCI coverage is 84.4% and 84.%, respectively. The color reproduction range is equivalent to 7%. Thus, in the light-emitting device 200 of Example 14, the emission intensity of 435 nm or less is reduced by 35% or more without reducing the numerical value of the color reproduction range. The relative luminance is maintained at 90% or higher.

Furthermore, in Examples 15 and 16, the first phosphor 71 is CBA having a spectral reflectance higher than CCA in the blue region, and the emission intensity reduction rates of 435 nm or less of Examples 15 and 16 are 39% and 35%, respectively. is there. Compared to 41% and 36% of the emission intensity reduction rates of Examples 13 and 14 in which the first phosphor 71 is CCA, the emission intensity reduction rate of 435 nm or less is slightly smaller. This is presumably because CBA has a higher reflectance than CCA in the blue region of the light emission wavelength region of the light emitting element 10, that is, it is difficult to absorb light emitted from the semiconductor light emitting element. However, the NTSC ratios at which the first phosphor 71 evaluates the color reproduction range in CCA Example 13 and CBA Example 15 are 86.1% and 86.2%, respectively, and the DCI coverage is 85.5%, respectively. It is the same value as%. The NTSC ratios of the first phosphor 71 in Example 14 of CCA and Example 16 of CBA are 83.5% and 83.6%, respectively, and the DCI coverage is the same value as 84.4%, respectively. When CBA is used as the first phosphor 71, the emission intensity reduction rate of 435 nm or less is slightly smaller than when CCA is used, but even if CBA is used, there is no practical problem as with CCA. it is conceivable that.
As described above, liquid crystal televisions, mobile devices, and the like that use the light-emitting device obtained according to the embodiment of the present invention as a backlight light source for liquid crystal can reduce the emission intensity of 435 nm or less without reducing the emission intensity. Can do. Therefore, the light emitting device according to the embodiment of the present invention can suppress, for example, adverse effects on the eyes.

  10: light emitting element, 50: fluorescent member, 70: phosphor, 71: first phosphor, 72: second phosphor, 73: third phosphor, 100, 200: light emitting device.

Claims (7)

A light emitting element having an emission peak wavelength in a range of 420 nm or more and 470 nm or less;
A fluorescent member including a first phosphor having a relative reflectance of 55% or less with respect to the reflectance of calcium hydrogen phosphate in a range of 380 nm to 435 nm and having an emission peak wavelength in a range of 450 nm to 470 nm;
A light emitting device comprising: The first phosphor has the following formula (Ca, Sr, Ba, Mg) ₁₀ (PO ₄ ) ₆ (F, Cl, Br, I, OH) ₂ : Eu
The light-emitting device according to claim 1, wherein the phosphor has a composition represented by: The first phosphor has the following formula Ca ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu
The light emitting device according to claim 1, having a composition represented by: The first phosphor has the following formula Ca ₁₀ (PO ₄ ) ₆ (Cl, Br) ₂ : Eu
The light emitting device according to claim 1, having a composition represented by:   5. The light emitting device according to claim 1, wherein the fluorescent member further includes a second phosphor having an emission peak wavelength in a range of 500 nm to 600 nm.   The light emitting device according to claim 5, wherein the fluorescent member further includes a third phosphor having an emission peak wavelength in a range of 620 nm to 670 nm.   The light emitting device according to claim 1, wherein the fluorescent member includes a resin, and a content ratio of the first phosphor to the resin is 1% by mass or more and 40% by mass or less.