JP6544082B2 - Light emitting device - Google Patents

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. ing. Such light emitting devices are used in a wide range of fields such as general lighting, vehicle lighting, displays, backlights for liquid crystals, and the like.

  On the other hand, yellow fluorescent lamps having a small amount of light components from ultraviolet to blue have generally been used for special lighting, particularly for illumination in an exposure room, and insect and low insecticidal lighting. In recent years, a yellow light with a polycarbonate yellow cover, an inexpensive silicone yellow film, or the like that cuts ultraviolet light to blue light is used for a white light emitting device using LEDs. In addition, a high-intensity light emitting device that emits a deep yellow light by using an LED is known (see, for example, Patent Document 1).

JP 2007-234877 A

When using a light emitting device of white light emission as a light source of yellow illumination, it is necessary to prepare a member such as a yellow cover and a yellow film separately from the light emitting device, and materials of those members (for example, resin) There was a problem such as deterioration. Further, in the light emitting device described in Patent Document 1, a member serving as a filter is essential in addition to the phosphor.
An embodiment of the present disclosure aims to provide a light emitting device in which blue light emission is suppressed and the light emission characteristic is excellent.

The specific means for solving the said subject is as follows, and the embodiment which concerns on this indication includes the following aspects.
The first embodiment has a light emitting element having an emission peak wavelength in a wavelength range of 430 nm to 485 nm, and a composition represented by the following formula (I), and is excited by light from the light emitting element to 500 nm to 580 nm And a fluorescent member containing a first phosphor that emits light having a light emission peak wavelength in the following wavelength range and a binder, wherein the content of the first phosphor in the fluorescent member is relative to the binder Of at least 80% by weight, and in the CIE 1931 chromaticity diagram, the first point where the chromaticity coordinates (x, y) are (0.444, 0.555), (0.416, 0.499) For the second point that is the third point that is (0.340, 0.570) and the fourth point that is (0.373, 0.624), the first point and the second point A first straight line connecting the second point and a second straight line connecting the second point and the third point; A third straight line connecting the point and the fourth point, a light emitting device that emits light in the range enclosed by the curve of the chromaticity diagram connecting the fourth point and the first point.
(Lu, Y, Gd, Tb) ₃ (Al, Ga) ₅ O ₁₂ : Ce (I)

The second embodiment has a light emitting element that emits light having an emission peak wavelength in a wavelength range of 430 nm to 485 nm, and a composition represented by the following formula (I), and is excited by light from the light emitting element A first phosphor that emits light having a light emission peak wavelength in the wavelength range of 500 nm to 580 nm, a composition represented by (II) below, a wavelength of 500 nm to 580 nm excited by light from the light emitting element And a fluorescent member containing a second phosphor that emits light having a light emission peak wavelength in the range and a binder, and the chromaticity coordinate (x, y) in the chromaticity diagram of CIE 1931 is (0.512, A fifth point which is 0.487), a sixth point which is (0.467, 0.448), a third point which is (0.340, 0.570) and (0.373, 0. 6). 624) to the fourth point And a fourth straight line connecting the fifth point and the sixth point, a fifth straight line connecting the sixth point and the third point, and a third line connecting the third point and the fourth point The light emitting device emits light in a range surrounded by a straight line and a curve of a chromaticity diagram connecting the fourth point and the fifth point.
(Lu, Y, Gd, Tb) ₃ (Al, Ga) ₅ O ₁₂ : Ce (I)
_{(Ca, Sr, Ba) 8} MgSi 4 O 16 (F, Cl, Br) 2: Eu (II)

  According to an embodiment of the present disclosure, it is possible to provide a light emitting device in which blue light emission is suppressed and the light emission characteristic is excellent.

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 schematic sectional drawing which shows another example of the light-emitting device which concerns on this embodiment. It is a figure which shows the example of the emission spectrum which shows the relative emission intensity with respect to the wavelength of the fluorescent substance which concerns on this embodiment. It is a figure which shows the example of the reflection spectrum which shows the reflectance with respect to the wavelength of the fluorescent substance which concerns on this embodiment. It is a figure which illustrates the emission spectrum which shows the relative luminescence intensity with respect to the wavelength of the light-emitting device concerning Example 1 and 2. FIG. It is the elements on larger scale of the emission spectrum which shows the relative luminescence intensity to the wavelength of the light-emitting device concerning Example 1 and 2. FIG. It is a figure which illustrates the emission spectrum which shows the relative emission intensity with respect to the wavelength of the light-emitting device concerning Example 3 and 4. It is the elements on larger scale of the emission spectrum which shows the relative emission intensity with respect to a wavelength about the emission spectrum of the light-emitting device concerning Example 3 and 4. FIG. It is the elements on larger scale of the emission spectrum which shows the relative emission intensity to a wavelength about the emission spectrum of the light-emitting device concerning Example 1 and 5 to 8. It is a figure which illustrates the emission spectrum which shows the relative emission intensity to a wavelength about the emission spectrum of the light-emitting device concerning Example 1 and 13 to 15. It is the elements on larger scale of the emission spectrum which shows the relative emission intensity with respect to a wavelength about the emission spectrum of the light-emitting device which concerns on Example 1 and 13-15. It is the elements on larger scale of the chromaticity diagram for showing the color tone of the light-emitting device concerning this embodiment.

Hereinafter, the light emitting device according to the present disclosure will be described based on the embodiment and the examples. However, the embodiments shown below exemplify light emitting devices for embodying the technical concept of the present invention, and the present invention does not specify the light emitting devices as the following.
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, etc. conform to JIS Z8110.
In the present specification, when there are a plurality of substances corresponding to each component in the composition, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless otherwise specified. means.

Light Emitting Device The light emitting device of the first aspect has a light emitting element having an emission peak wavelength in a wavelength range of 430 nm to 485 nm and a composition represented by the following formula (I), and is excited by light from the light emitting element And a fluorescent member containing a first phosphor that emits light having a light emission peak wavelength in the wavelength range of 500 nm to 580 nm and a binder, and the content of the first phosphor in the fluorescent member is The first point at which the concentration is 80% by weight or more with respect to the binder and in the chromaticity diagram of CIE 1931 the chromaticity coordinates (x, y) are (0.444, 0.555), (0.416 , 0.499), the third point (0.340, 0.570) and the fourth point (0.373, 0.624), the first point and the second point Connect the first straight line connecting the second point and the second and third points The range enclosed by the second straight line, the third straight line connecting the third point and the fourth point, and the curve of the chromaticity diagram connecting the fourth point and the first point It emits light with a range of
(Lu, Y, Gd, Tb) ₃ (Al, Ga) ₅ O ₁₂ : Ce (I)

The light emitting device of the second aspect has a light emitting element that emits light having a light emission peak wavelength in the wavelength range of 430 nm to 485 nm and a composition represented by the following formula (I); A first phosphor that emits light having an emission peak wavelength in the wavelength range of 500 nm to 580 nm when excited by light, has a composition represented by (II) below, and is 500 nm when excited by light from the light emitting element And a fluorescent member containing a second phosphor and a binder that emits light having a light emission peak wavelength in the wavelength range of not less than 580 nm, and in the chromaticity diagram of CIE 1931, the chromaticity coordinates (x, y) are The fifth point which is (0.512, 0.487), the sixth point which is (0.467, 0.448), the third point which is (0.340, 0.570) and (0 .373, 0.624) For a fourth point, a fourth straight line connecting the fifth point and the sixth point, a fifth straight line connecting the sixth point and the third point, a third point and a fourth point Emits light in a range (hereinafter, also referred to as a “second chromaticity coordinate range”) enclosed by the third straight line connecting the four points and the curve of the chromaticity diagram connecting the fourth point and the fifth point.
(Lu, Y, Gd, Tb) ₃ (Al, Ga) ₅ O ₁₂ : Ce (I)
_{(Ca, Sr, Ba) 8} MgSi 4 O 16 (F, Cl, Br) 2: Eu (II)

  Each of the light emitting devices according to the present embodiment has a light emitting element having a specific light emission peak wavelength and a composition represented by the formula (I), and a first phosphor having a light emission peak wavelength in a specific range and a binder And a light emission characteristic in the blue region is suppressed without requiring any other member such as a filter by being configured to emit light in the first chromaticity coordinate range. An excellent light emitting device can be configured. FIG. 9 shows the chromaticity coordinate range of light emitted by the light emitting device according to the present embodiment. FIG. 9 is a partially enlarged view of the chromaticity diagram, in which the first chromaticity coordinate range is included in the second chromaticity coordinate range.

  In the light emitting device according to the present embodiment, light emission in the blue region is suppressed. The blue region is, for example, a wavelength range of 460 nm or less. With respect to the emission spectrum of the light emitting device, the maximum emission intensity in the wavelength region is preferably less than 5%, more preferably 3.0% or less, with respect to the maximum emission intensity in the wavelength range of 500 nm or more. % Or less is more preferable, 2.0% or less is more preferable, and 1.5% or less is more preferable.

  The type of the light emitting device is not particularly limited, and can be appropriately selected from commonly used types. As a type of light emitting device, a pin penetration type, a surface mounting type, etc. can be mentioned. In general, the through-pin type refers to one in which a light emitting device is fixed by penetrating a lead (pin) of the light emitting device in a through hole provided in a mounting substrate. The surface mount type refers to one that fixes the leads of the light emitting device on the surface of the mounting substrate.

An example of a light emitting device according to the present embodiment will be described based on the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a light emitting device according to the present embodiment. This light emitting device is an example of a surface mounted light emitting device.
The light emitting device 100 emits light of a short wavelength side of visible light (for example, in the range of 380 nm to 485 nm), and a light emitting element 10 of gallium nitride compound semiconductor having an emission peak wavelength of 430 nm to 485 nm; And a molded body 40 on which is placed. The molded body 40 has a first lead 20 and a second lead 30, and is integrally molded of a sealing resin which is a thermoplastic resin or a thermosetting resin. The molded body 40 forms a recess having a bottom surface and a side surface, and the light emitting element 10 is mounted 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 the wire 60, respectively. The light emitting element 10 is covered by a fluorescent member 50. The fluorescent member 50 contains a first fluorescent substance 71 for converting the wavelength of light from the light emitting element 10 and a binder. As a binder constituting the fluorescent member 50, thermosetting resin such as epoxy resin, silicone resin, epoxy modified silicone resin, modified silicone resin, etc. can be used.

The fluorescent member 50 is formed by being filled with a translucent resin so as to cover the light emitting element 10 placed in the recess of the light emitting device 100. In consideration of the easiness of production, the binder contained in the fluorescent member is preferably a translucent resin. It is preferable to use a silicone resin composition as the translucent resin, but an insulating resin composition such as an epoxy resin composition or an acrylic resin composition can also be used. The fluorescent member 50 may contain glass instead of the translucent resin.
Although the first phosphor 71 is contained in the fluorescent member 50, other materials may be added as appropriate. For example, by including a light diffusing material, directivity from the light emitting element can be relaxed and a viewing angle can be increased.

  The fluorescent member 50 functions not only as a member for protecting the light emitting element 10 and the first fluorescent substance 71 from the external environment, but also as a wavelength conversion member. In FIG. 1, the first phosphor 71 is partially localized in the fluorescent member 50. By arranging the first phosphor 71 close to the light emitting element 10 as described above, the light from the light emitting element 10 can be efficiently wavelength-converted, and a light emitting device with excellent luminous efficiency can be obtained. The arrangement of the fluorescent member 50 including the first fluorescent substance 71 and the light emitting element 10 is not limited to the form in which the fluorescent substance 50 and the light emitting element 10 are arranged close to each other, considering the influence of heat on the first fluorescent substance 71 Alternatively, in the fluorescent member 50, the light emitting element 10 and the first fluorescent body 71 can be spaced apart. In addition, by mixing the first fluorescent substance 71 in the whole of the fluorescent member 50 at a substantially uniform ratio, it is possible to obtain light in which color unevenness is further suppressed.

FIG. 2 is a schematic cross-sectional view showing another example of the light emitting device according to the present embodiment. The light emitting device shown in FIG. 2 has the same configuration as the light emitting device shown in FIG. 1 except that the fluorescent member 50 includes the first fluorescent substance 71 and the second fluorescent substance 72 as fluorescent substances. . In FIG. 2, the first phosphor 71 and the second phosphor 72 are included in the fluorescent member 50 in a mixed state.
FIG. 3 is a schematic cross-sectional view showing another example of the light emitting device according to the present embodiment. In FIG. 3, the first phosphor 71 and the second phosphor 72 are stacked and arranged. Furthermore, as shown in FIG. 3, the first fluorescent substance 71 and the second fluorescent substance 72 can be arranged in order from the side closer to the light emitting element 10. As a result, since the second phosphor 72 absorbs extra light in the blue region that has not been absorbed by the first phosphor 71, from the state where the first phosphor 71 and the second phosphor 72 are mixed Also, light in the more blue region can be prevented from leaking out of the light emitting device.

Light emitting element The light emission peak wavelength of the light emitting element is in a wavelength range of 430 nm or more and 485 nm or less. By using a light emitting element having a light emission peak wavelength in this wavelength range as an excitation light source, it is possible to configure a light emitting device that emits mixed color light of light from the light emitting element and fluorescence from a fluorescent substance. The emission peak wavelength of the light emitting element is preferably 440 nm or more and 470 nm or less, and more preferably 445 nm or more and 460 nm or less.

The half width of the emission spectrum of the light emitting element is not particularly limited. The half width can be, for example, 30 nm or less.
It is preferable to use a semiconductor light emitting element as the light emitting element. By using a semiconductor light emitting element as a light source, it is possible to obtain a stable light emitting device with high efficiency, high output linearity with respect to input, and resistance to mechanical shock.
As a light emitting element, for example, a blue using a nitride-based semiconductor (In _x Al _y Ga _1-x-Y N, where X and Y satisfy 0 ≦ X, 0 ≦ Y, and X + Y ≦ 1), A semiconductor light emitting element that emits green light can be used.

The fluorescent member constituting the first fluorescent substance light emitting device has a composition represented by the above-mentioned formula (I), and is excited by light from the light emitting element to have an emission peak wavelength in a wavelength range of 500 nm to 580 nm. It contains at least one kind of one phosphor. The first phosphor preferably has a composition represented by at least one of the following formulas (Ia) and (Ib).
(Y, Gd) ₃ Al ₅ O ₁₂ : Ce (Ia)
Y ₃ (Al, Ga) ₅ O ₁₂ : Ce (Ib)

  The emission peak wavelength of the first phosphor is preferably 520 nm or more and 580 nm or less, and more preferably 530 nm or more and 570 nm or less. The half width of the emission spectrum of the first phosphor is, for example, 140 nm or less, preferably 130 nm or less. The half width is, for example, 90 nm or more, and preferably 100 nm or more.

As for the reflectance of the first phosphor, when the reflectance of the reference sample is 100%, the minimum value in the wavelength range of 430 nm to 470 nm is preferably 30% or less, and more preferably 20% or less.
The reflectance of the phosphor is measured using a spectrofluorimeter F-4500 manufactured by Hitachi High-Technologies Corporation and calcium hydrogen phosphate (CaHPO ₄ ) as a reference sample. The reflectance at each wavelength was determined by calculating the measured light intensity with the following formula.
Reflectance (%) = (Intensity of reflected light by sample / Intensity of reflected light by reference sample) × 100

The average particle size of the first phosphor is not particularly limited, and is, for example, 5 μm to 10 μm, preferably 5 μm to 8 μm, preferably 5 μm to less than 8 μm, and more preferably 5 μm to 6 μm.
In the present specification, the average particle size of the phosphor is a numerical value called Fisher Sub Sieve Sizer's No., and is measured using an air permeation method.
The fluorescent member may contain the first fluorescent substance singly or in combination of two or more.

  The content of the first phosphor contained in the fluorescent member is, for example, 80% by weight or more, preferably 130% by weight or more, and more preferably 170% by weight or more based on the binder. The content of the first phosphor is, for example, 230% by weight or less, preferably 210% by weight or less, based on the binder.

Second phosphor The phosphor member constituting the light emitting device has a composition represented by the above formula (II) in addition to the first phosphor, and is excited by light from the light emitting element to have a wavelength of 500 nm to 580 nm You may include at least 1 sort (s) of 2nd fluorescent substance which has an emission peak wavelength in a range.
The second phosphor contains at least one selected from the group consisting of Ca, Sr and Ba, but preferably contains at least Ca, and the Ca content is at least 90 mol% with respect to the total amount of Ca, Sr and Ba It is more preferable that The second phosphor contains at least one selected from the group consisting of F, Cl and Br, but preferably contains at least Cl, and the Cl content is 90 mol% with respect to the total amount of F, Cl and Br It is more preferable that it is more than.
Furthermore, the second phosphor preferably has a composition represented by the following formula (IIa).
Ca ₈ MgSi ₄ O ₁₆ Cl ₂ : Eu (IIa)

510 nm or more and 530 nm or less are preferable, and 515 nm or more and 525 nm or less of the emission peak wavelength of 2nd fluorescent substance are more preferable.
The half width of the emission spectrum of the second phosphor is, for example, 75 nm or less, and preferably 65 nm or less. The half width is, for example, 45 nm or more, and preferably 55 nm or more.
As for the reflectance of the second phosphor, the maximum value in the wavelength range of 400 nm to 470 nm is preferably 30% or less, and more preferably 20% or less.

The average particle diameter of the second phosphor is not particularly limited, and is, for example, 5 μm to 20 μm, preferably 8 μm to 15 μm, and more preferably 9 μm to 13 μm.
The fluorescent member may contain the second phosphor singly or in combination of two or more.

  The content of the second phosphor contained in the fluorescent member is, for example, 45% by weight or less, preferably 40% by weight or less, and more preferably 30% by weight or less based on the first phosphor. The content of the second phosphor is, for example, 10% by weight or more, and preferably 20% by weight or more based on the first phosphor.

  The total content of the first phosphor and the second phosphor in the fluorescent member is, for example, 80% by weight or more, preferably 130% by weight or more, and more preferably 150% by weight or more based on the binder. Further, the total content is, for example, 230% by weight or less, preferably 210% by weight or less, with respect to the binder. If the amount of phosphors is too large, the viscosity of the binder containing the phosphors will increase, and in the process of manufacturing the light emitting device, the workability of arranging the binder containing the phosphors in a predetermined position will be worse. It is.

Other Phosphors The fluorescent member does not exclude the inclusion of a phosphor other than the first phosphor and the second phosphor, and the phosphors other than the first phosphor and the second phosphor are for the purpose of the present disclosure. You may contain to the extent which does not impair. Other phosphors include Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce, CaSc ₂ O ₄ : Ce, (La, Y) ₃ Si ₆ N ₁₁ : Ce, (Ca, Sr, Ba) ₃ Si ₆ O ₉ N ₄ : Eu, (Ca, Sr, Ba) ₃ Si ₆ O ₁₂ N ₂ : Eu, (Ba, Sr, Ca) Si ₂ O ₂ N ₂ : Eu, (Sr, Ca) AlSiN ₃ : Eu, (Ca , Sr, Ba) ₂ Si ₅ N ₈ : Eu, (Ca, Sr, Ba) S: Eu, (Ba, Sr, Ca) Ga ₂ S ₄ : Eu, K ₂ (Si, Ti, Ge) F ₆ : Mn, (Ca, Sr, Ba, Mg) ₁₀ (PO ₄ ) ₆ (F, Cl, Br, I, OH) ₂ : Eu, 3.5MgO · 0.5MgF ₂ · GeO ₂ : Mn, Sr ₄ Al ₁₄ O _25: citing Eu or the _{like: Eu, (Si, Al)} 6 (O, N) 8 It is possible. When the fluorescent member contains other phosphors, the content thereof can be appropriately selected according to the purpose and the like. The content of the other phosphors is, for example, 30% by weight or less in the total amount of phosphors, and may be 1% by weight or less.
When the fluorescent member includes the other phosphors in addition to the first phosphor 71 and the second phosphor 72, and the respective phosphors are disposed, the influence of the light absorption between the phosphors is made more effective. For example, (Sr, Ca) AlSiN ₃ : Eu, the first phosphor or the second phosphor can be disposed in order from the side of the light emitting element.

Binder The fluorescent member contains at least one binder. As a binder which comprises a fluorescence member, a thermoplastic resin and a thermosetting resin are mentioned. Specific examples of the thermosetting resin include epoxy resins, silicone resins, and modified silicone resins such as epoxy-modified silicone resins.

  The fluorescent member may optionally contain other components in addition to the fluorescent substance and the binder. Examples of the other components include fillers such as silica, barium titanate, titanium oxide and aluminum oxide, light stabilizers, colorants and the like. When the fluorescent member contains other components, the content thereof is not particularly limited, and can be appropriately selected according to the purpose and the like. For example, when the filler is contained as another component, the content thereof can be 0.01 to 20 parts by weight with respect to 100 parts by weight of the binder.

  Examples according to the present disclosure will be specifically described below, but the present disclosure is not limited to these examples.

The following phosphors were prepared respectively.
Phosphors 1a and 1b having a composition represented by the following formula (Ia) as a first phosphor, and having an emission peak wavelength of 570 nm and an average particle diameter of 10 μm, 8 μm, 7 μm, 6 μm or 5 μm , 1c, 1d and 1e, and phosphor 2 having a composition represented by the following formula (Ib), an emission peak wavelength of 533 nm, and an average particle diameter of 9 μm.
(Y _0.81 Gd _0.19 ) ₃ Al ₅ O ₁₂ : Ce (Ia)
Y ₃ (Al _0.8 Ga _0.2 ) ₅ O ₁₂ : Ce (Ib)
Moreover, as a second phosphor, a phosphor 3 having a composition represented by the following formula (IIa), an emission peak wavelength of 520 nm, and an average particle diameter of 11 μm was prepared.
Ca ₈ MgSi ₄ O ₁₆ Cl ₂ : Eu (IIa)
The emission spectrum of the prepared phosphors 1a, 2 and 3 at an excitation wavelength of 450 nm is shown in FIG. 4A. In FIG. 4A, normalized emission spectra are shown showing the relative emission intensity versus wavelength for each phosphor. Also, the reflection spectra of those phosphors are shown in FIG. 4B. In FIG. 4B, a reflection spectrum is shown which shows the reflectance with respect to wavelength.

Evaluation Method (1) Average Particle Size The average particle size of the phosphor is F.I. S. S. S. No. It is a value called (Fisher Sub Sieve Sizer's No.) and obtained by an air permeation method. Specifically, after taking a sample of 1 cm ³ min at an ambient temperature of 25 ° C and humidity of 70%, packing it into a special tubular container, flowing dry air at a constant pressure, reading the specific surface area from the differential pressure And the average particle diameter. The average particle size was measured using Fisher Scientific's Fisher Sub-Sieve Sizer Model 95.

(2) Blue peak intensity From the emission spectrum of the light emitting device, the blue peak intensity was calculated as the ratio (%) of the maximum emission intensity in the wavelength range of 460 nm or less to the maximum emission intensity in the wavelength range of 500 nm or more.
(3) Relative luminous flux The total luminous flux of the light emitting device is measured using an integral type total luminous flux measuring device, and is shown as a relative luminous flux (%) when the total luminous flux of the light emitting device of Example 1 is 100%.

(4) Reflectance For the measurement of the reflectance of the phosphor, a spectrofluorimeter F-4500 manufactured by Hitachi High-Technologies Corporation was used. The method of measuring the reflectance will be specifically described below. A xenon lamp was used as the light source and light from the light source was introduced into the first monochromator. Of the introduced light, only the target wavelength was selected by the first monochromator, and the sample for which the reflectance was to be determined was irradiated. The light reflected by the sample was introduced into the second monochromator, and the same wavelength as the wavelength selected by the first monochromator was also selected with the second monochromator. The light selected by the second monochromator was introduced into a photomultiplier to measure the light intensity. Subsequently, the wavelengths selected by the first monochromator and the second monochromator were synchronously changed, and the light intensity in the desired wavelength range was measured. Calcium hydrogen phosphate (CaHPO ₄ ) was used as a reference sample of reflectance, and the intensity of light reflected from the reference sample was measured in the same procedure as the above-described sample. The reflectance at each wavelength was determined by calculating the measured light intensity with the following formula.
Reflectance (%) = (Intensity of reflected light by sample / Intensity of reflected light by reference sample) × 100

Example 1
Production of Light-Emitting Device A surface-mounted light-emitting device was produced by combining the first light-emitting phosphor 1a with a blue light-emitting LED having an emission peak wavelength of 455 nm.
The phosphor-containing resin composition is prepared by blending the phosphor 1a and the silicone resin so that the content of the phosphor 1a is 180% by weight with respect to the silicone resin as the binder, mixing and dispersing, and further defoaming. I got a thing. Next, this phosphor-containing resin composition was injected onto the light emitting element, filled, and heated to cure the resin composition. A light emitting device was manufactured by such a process.
The chromaticity coordinates (x, y) of the light emission color, the blue peak intensity and the relative luminous flux were measured for the obtained light emitting device. The results are shown in Table 1 below. The emission spectrum of the obtained light emitting device of Example 1 is shown in FIGS. 5A and 5B. 5B is a partially enlarged view of the range of 400 nm to 500 nm in FIG. 5A. In FIGS. 5A and 5B, normalized emission spectra are shown that show relative emission intensities versus wavelength.

(Examples 2 to 4, Comparative Example 1)
A light emitting device was produced and evaluated in the same manner as in Example 1 except that the type and content of the phosphor were changed as shown in Table 1 below. The results are shown in Table 1 below. The emission spectrum of the obtained light emitting device of Example 2 is shown together with Example 1 in FIGS. 5A and 5B. The emission spectra of the obtained light emitting devices of Examples 3 and 4 are shown in FIGS. 6A and 6B. 6B is a partially enlarged view of the range of 400 nm to 500 nm in FIG. 6A. In FIGS. 6A and 6B, normalized emission spectra are shown which show relative emission intensities with respect to wavelength.

It is understood from Table 1 that the blue peak intensity increases to 5% or more when the content of the first phosphor is less than 80% by weight with respect to the binder. In addition, it can be seen that the blue peak intensity decreases as the content of the first phosphor increases.
The light emitting device using the phosphor 2 has a higher luminous flux than the light emitting device using the phosphor 1 a. This is considered to be because, for example, as shown in FIG. 4A, the phosphor 2 overlaps with the visibility curve more than the phosphor 1a.

(Examples 5 to 8)
A light emitting device was produced and evaluated in the same manner as in Example 1 except that as the first phosphor, different phosphors 1b to 1e were used as shown in Table 2 below as average particle diameter. The results are shown in Table 2 below. Further, a partially enlarged view of the emission spectrum of the light emitting device of Examples 5 to 8 is shown in FIG. 7 together with that of Example 1. FIG. 7 shows an emission spectrum showing relative emission intensity with respect to wavelength.

  As shown in Table 2, it can be seen that the blue peak intensity is reduced by using a phosphor having a small average particle diameter even if the content of the phosphor is the same. In other words, when the blue peak intensities are the same, the phosphor content can be reduced as much as possible by decreasing the average particle diameter of the phosphor to be used.

(Examples 9 to 12)
A light emitting device was produced and evaluated in the same manner as in Example 1 except that the type and content of the phosphor were changed as shown in Table 3 below. The results are shown in Table 3 below.

  It is understood from Table 3 that as the average particle diameter of the phosphor is smaller, the value of blue peak intensity is less than 5% even if the content of the phosphor is small. This can be described, for example, as follows. When the average particle size of the phosphors is small, the phosphors tend to be densely packed in the fluorescent member, that is, the gap between the phosphors is reduced. It is speculated that blue light of 460 nm or less emitted from the light emitting element is efficiently absorbed by the phosphor without passing through the gap between the phosphor and the phosphor, and it becomes difficult to be emitted outside the light emitting device Ru.

(Examples 13 to 15)
Using the phosphor 1a that is the first phosphor and the phosphor 3 that is the second phosphor in the compounding ratio shown in Table 4 so that the total content of the phosphor is 180% by weight with respect to the silicone resin A light emitting device was produced in the same manner as in Example 1 except for the above, and was evaluated in the same manner. The results are shown in Table 4 below. The emission spectra of the light emitting devices of Examples 13 to 15 are shown in FIGS. 8A and 8B together with that of Example 1. FIG. 8B is a partially enlarged view of the range of 400 nm to 500 nm in FIG. 8A. In FIGS. 8A and 8B, normalized emission spectra showing relative emission intensities with respect to wavelength are shown.

When the blending ratio of the second phosphor, phosphor 3, was increased, the blue peak intensity tended to decrease. For example, as shown in FIG. 4B, the reflectance of the second phosphor is lower in a short wavelength region (for example, 400 nm or more and around 450 nm or less) than that of the first phosphor, and It is presumed that it is easy to absorb light. This means that, for example, at the emission peak shown in FIG. 8B, the peak wavelength of emission shifts to a longer wavelength side as the compounding ratio of the second phosphor, phosphor 3, increases from Example 13 to Example 15 It can be confirmed from the fact that light in the shorter wavelength region is absorbed.
In addition, the luminous flux is improved by increasing the blending ratio of the second phosphor. It is presumed that the luminous flux is improved as a result of the emission spectrum approaching the peak of the visibility curve (around 555 nm).

  The light-emitting device according to the present disclosure is particularly useful for lighting applications.

  10: light emitting element, 50: fluorescent member, 71: first phosphor, 72: second phosphor, 100: light emitting device

Claims (4)

A light emitting element having an emission peak wavelength in a wavelength range of 430 nm to 485 nm;
It has a composition represented by the following formula (Ia) or (Ib) , has an average particle diameter of 10 μm or less, and has an emission peak wavelength in a wavelength range of 500 nm to 580 nm when excited by light from the light emitting element A first phosphor emitting light, having a composition represented by (IIa) below, and a second fluorescence emitting light having an emission peak wavelength in a wavelength range of 500 nm to 580 nm excited by light from the light emitting element And a fluorescent member containing a body and a binding agent,
The total content of the first phosphor and the second phosphor in the fluorescent member is 80% by weight or more with respect to the binder,
In the CIE 1931 chromaticity diagram, the fifth point where the chromaticity coordinates (x, y) are (0.512, 0.487), the sixth point where (0.467, 0.448), For a third point which is 0.340, 0.570) and a fourth point which is (0.373, 0.624), a fourth straight line connecting the fifth point and the sixth point; The fifth straight line connecting the sixth point and the third point, the third straight line connecting the third point and the fourth point, and the curve of the chromaticity diagram connecting the fourth point and the fifth point A light emitting device that emits light in the range enclosed by.
(Y, Gd) ₃ Al ₅ O ₁₂ : Ce (Ia)
Y ₃ (Al, Ga) ₅ O ₁₂ : Ce (Ib)
Ca ₈ MgSi ₄ O ₁₆ Cl ₂ : Eu (IIa) The content of the second phosphor, the light emitting device according to claim 1 wherein is 45 wt% or less with respect to the first phosphor. The light emitting device according to claim 1 or 2 , wherein a content of the second phosphor is 10% by weight or more with respect to the first phosphor. The light emitting device according to any one of claims 1 to 3 , having a light emission spectrum in which the maximum light emission intensity in the wavelength range of 460 nm or less is less than 5% with respect to the maximum light emission intensity in the wavelength range of 500 nm or more.