JP2018107418A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device which enables the suppression of color shift according to an angle at the time of visual recognition.SOLUTION: The present invention relates to a light-emitting device comprising: a light-emitting element 20 having an emission face and emitting light first light having an emission peak wavelength in a range of 380 nm or more and 430 nm or less; a phosphor layer 30 disposed on the emission face of the light-emitting element 20, and containing a phosphor which is excited by the first light and emits second light longer, in wavelength, than the first light; and a reflective film 40 provided on the phosphor layer 30, reflecting the first light, and allowing the second light to pass therethrough. According to reflection spectra of the reflective film 40, the reflective film 40 is 40% or more in reflectance to light in a range of 380 nm or more and 430 nm or less when an incident angle of the first light incident on the reflective film 40 is 0° to 85°.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light emitting device.

Light emitting devices using light emitting diodes (LEDs) are widely used as displays, warning lights, indicator lights, and illumination lights.
For example, illumination that forms a tail lamp and a brake lamp of an automobile that emits red light by a blue light emitting diode that emits blue light and a phosphor that converts light from the blue light emitting diode into red is known (for example, patents). References 1 and 2).

JP-A-2015-88220 Japanese Patent Laying-Open No. 2015-88483

  However, the light emitting devices disclosed in Patent Documents 1 and 2 may cause a color shift of red light depending on the angle at which the light emitting device is viewed.

  Therefore, the light emitting device according to the present embodiment aims to provide a light emitting device that can suppress a color shift due to a viewing angle.

  The light emitting device according to the present embodiment is arranged on the light emitting surface of the light emitting element, the light emitting element having a light emitting surface that emits first light having an emission peak wavelength of 380 nm to 430 nm, and the first light emitting device. A phosphor layer containing a phosphor that is excited by light and emits second light having a longer wavelength than the first light, and is provided on the phosphor layer, reflects the first light, and A reflection film that transmits the second light, and in the reflection spectrum of the reflection film, the reflection film has an incident angle of the first light with respect to the reflection film of 380 nm or more at 0 ° to 85 ° The reflectance of light of 430 nm or less is 40% or more.

  In another aspect, the light emitting device according to this embodiment is formed by sequentially stacking a first semiconductor layer, an active layer, and a second semiconductor layer that emits first light having an emission peak wavelength of 380 nm to 430 nm. A phosphor layer including a light emitting element, a phosphor disposed on the light emitting element and excited by the first light and emitting a second light having a longer wavelength than the first light; and the phosphor And a reflective film that is provided on the layer and reflects the first light and transmits the second light, and the reflection with respect to the center of the active layer in a plan view of the light emitting element The reflectance of light between 380 nm and 430 nm in the range of −85 ° to + 85 ° in the film direction is 40% or more.

  Accordingly, it is possible to provide a light emitting device that can suppress color misregistration due to a viewing angle.

It is a schematic sectional drawing which shows an example of the light-emitting device which concerns on embodiment. 3 is a chromaticity diagram illustrating chromaticity coordinates (CIE1931) of light emitted from the light emitting device according to Embodiment 1. FIG. It is a figure which shows the reflectance with respect to the wavelength of a reflecting film in case the light enters perpendicularly (incident angle 0 degree) in the light-emitting device which concerns on Example 1. FIG. 6 is a diagram illustrating a shift in chromaticity coordinates x depending on a directivity angle in the light-emitting devices of Example 1, Example 2, and Comparative Example 1. FIG. It is a figure which shows the shift | offset | difference of the chromaticity coordinate y by the directivity angle in the light-emitting device of Example 1, Example 2, and the comparative example 1. FIG. FIG. 4 is a graph showing an emission spectrum of the light emitting device according to Example 1, Example 2, and Comparative Example 1. 6 is a graph showing an emission spectrum of a light emitting device according to Example 1, Example 2, and Comparative Example 1. FIG. It is a figure which shows the reflectance in the incident angle of the 1st light which the light emitting element emits with respect to a reflecting film. It is a figure which shows the reflectance in the incident angle of the 1st light which the light emitting element emits with respect to a reflecting film. (Sr, Ca) AlSiN _3: Eu as the phosphor, CaAlSiN _3: is a spectrum diagram showing the powder reflectance of Eu phosphor.

Hereinafter, the light emitting device according to the embodiment will be described with reference to the embodiment and examples. However, the present invention is not limited to this embodiment and examples. The embodiment described below exemplifies a light emitting device for embodying the technical idea of the present invention, and the present invention is not limited to the following light emitting device.
The relationship between the color name and chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, and the like comply with JIS Z8110. Specifically, 380 nm to 410 nm is purple, 410 nm to 455 nm is blue purple, 455 nm to 485 nm is blue, 485 nm to 495 nm is blue green, 495 nm to 548 nm is green, 548 nm to 573 nm is yellow green, 573 nm to 584 nm is yellow, 584 nm to 610 nm is yellowish red, and 610 nm to 780 nm is red.

In the light emitting device and the manufacturing method thereof according to the embodiment, “upper”, “lower”, “left”, “right”, and the like are interchanged depending on the situation. In the present specification, “upper”, “lower” and the like indicate relative positions between components in the drawings referred to for explanation, and indicate absolute positions unless otherwise specified. Not intended.
In the present specification, the “upper” in the light emitting element “upper”, the phosphor layer “upper”, the reflective film “upper”, etc. is not limited to the contacted form, and other members are arranged in between without contacting. It may be a form. For example, when “arranged on the A member” such as “arranged on the light emitting surface of the light emitting element 20”, the case where it is provided in contact with the A member and another layer on the A member via And the case where it is provided.
In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, the content of each component in the composition means 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.

  Hereinafter, the light-emitting device according to Embodiment 1 will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating an example of a light emitting device according to an embodiment. FIG. 2 is a chromaticity diagram showing chromaticity coordinates (CIE1931) of light emitted from the light emitting device according to the first embodiment. The incident angle A of the first light with respect to the reflective film indicates the incident angle A shown in FIG. Unless otherwise specified, the center of the active layer is used as a reference in the plan view of the light emitting element. Assuming that the first light is emitted from the center of the active layer, the incident angle A is defined.

  The light emitting device 100 includes a base 10, a light emitting element 20 disposed on the base 10, a phosphor layer 30 disposed on the light emitting element 20, and a reflective film 40 provided on the phosphor layer 30. Prepare. The light emitting device 100 further includes a translucent member 50 provided on the reflective film 40. The base 10 is provided on the first lead 11, the second lead 12, the fixing portion 13 disposed between the first lead 11 and the second lead 12, and the first lead 11 and the second lead 12. It has a side wall 14. The base 10 is formed with a recess 15, the first lead 11, the second lead 12, and the fixing portion 13 are disposed on the inner bottom surface 16 of the recess 15, and the side wall 14 is disposed on the inner surface 17 of the recess 15. . The light emitting element 20 is disposed on the inner bottom surface 16 of the recess 15 of the base 10, and the resin 70 is disposed in the recess 15 of the base 10 so as to be in contact with the translucent member 50. The light emitting element 20 may be disposed on the inner bottom surface 16 of the recess 15 using a die bond material such as a metal such as gold or solder or a resin such as an epoxy resin. The uppermost surface of the recess 15 of the base 10 is preferably located at a position higher than the surface of the translucent member 50 with reference to the inner bottom surface 16 of the recess 15 of the base 10. Thereby, the translucent member 50 can be prevented from falling off.

The light emitting element 20 emits first light having an emission peak wavelength in the range of 380 nm to 430 nm. The light emitting element 20 includes a semiconductor stacked body 21 and a substrate 22. The semiconductor stacked body 21 is stacked in the order of the first semiconductor layer 21a, the active layer 21b, and the second semiconductor layer 21c. The light emitting element 20 has a light emitting surface on either the substrate 22 side or the semiconductor laminate 21 side.
The light emitting element 20 preferably has a relative intensity at 450 nm of 0.3 or less and more preferably a relative intensity at 450 nm of 0.1 or less when the maximum intensity of the emission peak wavelength is 1. Thereby, it is possible to reduce the emission of light near 450 nm to the outside.

The phosphor layer 30 contains a phosphor that is excited by the first light and emits second light having a longer wavelength than the first light. The phosphor layer 30 may be formed of only a phosphor, and the phosphor may be solidified with an organic substance such as a resin or an inorganic substance such as a ceramic. The phosphor layer 30 is excellent in heat resistance when the phosphor particles are baked and hardened. When the phosphor particles are dispersed in an epoxy resin or a silicone resin, the phosphor layer 30 can be easily formed. A product obtained by baking and solidifying phosphor particles and ceramic particles is also excellent in heat resistance. These are appropriately selected according to the purpose and application.
The phosphor contained in the phosphor layer 30 preferably has an emission peak wavelength in the range of 550 nm to 780 nm, and more preferably has an emission peak wavelength in the range of 584 nm to 680 nm. This is because the emission luminance can be increased by having the emission peak wavelength in this range. Moreover, it is because red light emission is easy to visually recognize.

The reflective film 40 has a property of reflecting the first light and transmitting the second light. In the reflection spectrum of the reflection film 40, the reflection film 40 has a reflectance of 40% or more of light of 380 nm or more and 430 nm or less when the incident angle A of the first light with respect to the reflection film 40 is 0 ° to 85 °. Is 45% or more. When the incident angle A of the first light with respect to the reflective film 40 is 0 ° to 45 °, the reflectance of light of 380 nm to 430 nm is preferably 90% or more, and more preferably 95% or more. . When the incident angle A between the first light and the reflective film 40 is 0 °, the reflective film preferably has a reflectance of 380 nm or more and 530 nm or less of 90% or more, and more preferably has a reflectance of 95% or more. preferable.
Thereby, even when the incident angle A between the first light and the reflective film 40 is not vertical (0 °), the light-emitting device 100 can suppress the transmission of the first light and suppress the color shift due to the viewing angle. Can provide.
The reflectance of light of 380 nm to 430 nm in the range of −85 ° to + 85 ° in the direction of the reflective film 40 with respect to the center of the active layer 21b in a plan view of the light emitting element 20 is 40% or more. This angle is the same angle as the incident angle A.

The translucent member 50 mainly transmits the second light. The translucent member 50 can be made of an inorganic material such as ceramics or glass, or an organic material such as a resin. For example, what consists of a transparent glass plate with the flat surface which the reflective film 40 touches can be used.
The phosphor layer 30 disposed on the light emitting element 20 may be disposed via the adhesive layer 60. The adhesive layer 60 is preferably translucent. By using the adhesive layer 60, the phosphor layer 30 can be easily disposed on the light emitting element 20. Further, the phosphor layer 30 disposed on the light emitting element 20 may be directly joined without using an adhesive. By directly joining the light emitting element 20 and the phosphor layer 30, heat generated in the phosphor layer 30 can be radiated through the light emitting element 20.
The reflective film 40 can be used alone, but the reflective film 40 can also be formed on the translucent member 50 by printing or coating. The reflective film 40 can be easily provided by using a member having high strength as the translucent member 50. The reflective film 40 can also be formed on the phosphor layer 30 by printing or coating.

The resin 70 disposed on the inner bottom surface 16 of the recess 15 may be disposed on the side surface of the translucent member 50 except for the upper surface of the translucent member 50. In addition to the side surface of the translucent member 50, the resin 70 may be disposed so as to cover the light emitting element 20, the phosphor layer 30, and the reflective film 40. Accordingly, the resin 70 reflects both the first light from the light emitting element 20 and the second light from the phosphor layer 30.
The resin 70 preferably contains at least one light diffusing material selected from the group consisting of zirconium oxide, yttrium oxide, aluminum oxide, aluminum hydroxide, barium carbonate, barium sulfate, magnesium oxide and magnesium carbonate. Thereby, the first light from the light emitting element 20 can be irradiated to the resin 70 containing the light diffusing material and returned to the phosphor layer 30 side, and the light emission efficiency of the second light from the phosphor layer 30 can be improved. Can be increased. Further, the resin 70 may contain titanium oxide. Titanium oxide is absorbed without reflecting light on the shorter wavelength side than 420 nm, but light on the longer wavelength side than 420 nm is efficiently reflected, so the light emitting element 20 having an emission peak wavelength between 420 nm and 430 nm is used. In that case, the resin 70 may contain titanium oxide.
Thereby, the light emitted from the light emitting device 100 is emitted having an emission spectrum substantially equal to the emission spectrum of the second light emitted from the phosphor layer 30.

  The light emitting element 20 has a pair of positive and negative electrodes on the same surface side, is mounted face down, and the light emitting element 20 and the first lead 11 and the second lead 12 are electrically connected by a conductive bonding member. . Instead of face-down mounting, face-up mounting can be performed. In the case of face-up mounting, instead of the conductive bonding member, the first lead 11 and the second lead 12 may be connected using wires.

  The reflection film 40 is provided on the phosphor layer 30, reflects the first light emitted from the light emitting element 20, and transmits the second light emitted from the phosphor layer 30. The reflective film 40 can be constituted by, for example, a dielectric multilayer film in which first dielectric layers 41 and second dielectric layers 42 having different refractive indexes are alternately stacked. The dielectric multilayer film is a film of the first dielectric layer 41 and a film of the second dielectric layer 42 based on the first refractive index of the first dielectric layer 41 and the second refractive index of the second dielectric layer 42. By setting the thickness, the first light emitted from the light emitting element 20 can be reflected, and the second light emitted from the phosphor layer 30 can be transmitted.

  Further, in the light emitting device 100, since the light emitting element 20 and the phosphor layer 30 are covered with the resin 70 and the reflective film 40, the second light emitted from the phosphor layer 30 is emitted through the reflective film 40. However, the first light emitted from the light emitting element 20 is reflected by the resin 70 and the reflective film 40 and returned to the phosphor layer 30 side, so that the phosphor can be excited and the luminous efficiency can be increased. Thereby, the emission of the first light emitted from the light emitting device 100 to the outside is suppressed, and the light emitted from the light emitting device 100 to the outside is substantially only the second light of the phosphor layer 30. In addition, the color misregistration in the vertical direction with respect to the semiconductor stacked body 21 can be prevented. However, when the incidence of the first light and the reflection film 40 is not perpendicular, a part of the first light is transmitted.

  In the light emitting device 100, when a dielectric multilayer film is used as the reflective film 40, almost all the light incident perpendicularly (0 °) to the dielectric multilayer film is reflected, but part of the light that is not perpendicularly incident is reflected. To Penetrate. In order to reduce the emission of light that is not perpendicularly incident, the thickness of the phosphor layer 30 is increased to reduce the incident amount of the first light from the light emitting element 20 to the dielectric multilayer film. It is effective that most of the first light from the light emitting element 20 is absorbed by the phosphor before it reaches the dielectric multilayer film to excite the phosphor. However, since the emission intensity decreases when the thickness of the phosphor layer 30 is increased, the emission intensity is reduced by reducing the phosphor layer 30 to the extent that the first light emitted from the light emitting element 20 can be emitted to the outside. Higher is preferred. Specifically, in the emission spectrum of the light emitting device 100, when the maximum intensity is 1, the relative intensity at 450 nm is preferably 0.3 or less.

  The light emitting device 100 has (x = 0.645, y = 0.335), (x = 0.665, y = 0.335), (x = 0.0.3) in the xy chromaticity coordinate system of the CIE1931 chromaticity diagram. 735, y = 0.265), (x = 0.721, y = 0.259), and emits light within a range surrounded by a rectangle formed by connecting the four points. With such a configuration, it is possible to provide a light emitting device that emits light in a predetermined red color and suppresses a color shift due to an angle.

The phosphor contained in the phosphor layer 30 may be at least one selected from (Sr, Ca) AlSiN ₃ : Eu phosphor, CaAlSiN ₃ : Eu phosphor, and K ₂ SiF ₆ : Mn phosphor. preferable. Moreover, it is good also as the combination. Accordingly, it is possible to provide a light emitting device that emits light in a predetermined red color and suppresses a color shift due to an angle.

As long as the light emitting device 100 is covered with the resin 70 except for the uppermost surface of the translucent member 50, for example, a bullet type, a surface mount type, a chip type, or the like may be used. In general, the bullet shape refers to a shape in which the shape of the resin constituting the outer surface is formed into a bullet shape. For example, it includes a lead frame having a cup on one side, a light emitting element disposed in the cup, and a sealing resin that covers a part of the light emitting element and the lead frame. In addition, the surface mount type refers to the one formed by placing a light emitting element in a concave storage portion and filling the light emitting element with resin. Examples of the material of the housing part include those made of thermoplastic resin, thermosetting resin, ceramics, metal, and the like. Further, the chip type does not have a concave accommodating portion unlike the surface mount type, and a phosphor is directly formed on the light emitting element, and the side surface of the light emitting element is fixed with a resin. In the chip type, the layer containing the phosphor may be a flat plate shape or a lens shape.
Here, the details will be described taking the surface mount type as an example.

[Base]
For the fixing portion 13 and the side wall 14 of the base 10, a resin such as a thermoplastic resin or a thermosetting resin, an inorganic material such as ceramics or glass, a metal subjected to an insulation process, or the like can be used.
It is preferable that the surface mount type base 10 has an insulating property and does not easily transmit light. Examples of the material of the base 10 include ceramics such as alumina and aluminum nitride, resins such as phenol resin, epoxy resin, polyimide resin, BT resin, and polyphthalamide. In addition, when using resin, you may mix inorganic fillers, such as glass fiber, a silicon oxide, a titanium oxide, an alumina, with a resin as needed. Among these, ceramics is more preferable because of its high heat dissipation effect.
The base 10 includes a first lead 11, a second lead 12, and a fixing portion 13. The base 10 is mainly a top view type that emits light in a direction substantially perpendicular to the mounting surface, and a side view type that emits light in a direction substantially parallel to the mounting surface. be able to. The first lead 11 and the second lead 12 are formed of a plate-like metal. Here, the first lead 11 and the second lead 12 do not protrude outward from the fixed portion 13 when viewed from the opening direction of the recess 15, but a configuration protruding outward from the fixed portion 13 can be employed.

  The material constituting the first lead 11 and the second lead 12 is, for example, a metal having a thermal conductivity of about 200 W / (m · K) or more, a material having a relatively large mechanical strength, Alternatively, a material that can be easily punched or etched is preferable. Specific examples include metals such as copper, aluminum, gold, silver, tungsten, iron and nickel, and alloys such as iron-nickel alloys and phosphor bronze. Further, the surface of the base material of the first lead 11 and the second lead 12 may be coated with silver, aluminum, gold or the like having a higher light reflectance than the base material.

[Light emitting element]
The light emitting element 20 is for exciting the phosphor contained in the phosphor layer 30. As the light emitting element 20, for example, a light emitting diode (LED) chip or a laser diode (LD) chip can be used, and among these, an LED chip is preferably used. By using the light emitting element 20 as the light emitting diode chip, the light from the light emitting element 20 can easily spread, so that the phosphor can be excited efficiently. As the light emitting element 20, for example, a blue light emitting diode chip containing a nitride semiconductor is used. Here, the blue light emitting diode chip refers to a chip having an emission peak wavelength in the range of 380 nm to 430 nm. The light emitting element 20 includes a semiconductor stacked body 21 and a substrate 22. The semiconductor laminate 21 may be laminated on a substrate, or may be a laminate of the semiconductor laminate 21 on a substrate different from the growth substrate.

Nitride semiconductor as referred to herein, the general _{formula: In X Al Y Ga 1-} X-Y N (0 ≦ X, 0 ≦ Y, X + Y ≦ 1) is a semiconductor represented by the composition and its mixed semiconductor layer Various emission wavelengths can be selected depending on crystallinity. The light emitting element 20 using a nitride semiconductor includes, for example, a substrate 22 on which a nitride semiconductor such as sapphire can be grown, and a semiconductor stacked body 21 provided on the substrate 22.

  In the light emitting element 20, the semiconductor stacked body 21 is provided with a first semiconductor layer 21a, an active layer 21b, and a second semiconductor layer 21c. The first semiconductor layer 21a and the second semiconductor layer 21c have different polarities. For example, a p-type semiconductor layer is used for the first semiconductor layer 21a, an n-type semiconductor layer is used for the second semiconductor layer 21c, a p-electrode is connected to the p-type semiconductor layer, and an n-electrode is connected to the n-type semiconductor layer. Has been. The p electrode and the n electrode are formed on the same surface of the light emitting element 20, and are preferably flip-chip mounted on the first lead 11 and the second lead 12. Thereby, the upper surface of the light emitting element 20 becomes a flat surface, and the phosphor layer 30 can be disposed close to the upper side of the light emitting element 20. Although the light emitting element 20 includes the substrate 22, the substrate 22 may be removed during or after mounting, and the phosphor layer 30 may be bonded directly or via the adhesive layer 60 on the semiconductor stacked body 21.

[Phosphor layer]
The phosphor layer 30 absorbs the first light from the light emitting element 20 and generates light of different wavelengths. The phosphor layer 30 is formed, for example, by printing a translucent resin paste containing phosphor particles on the surface of the translucent member via the reflective film 40. The phosphor layer 30 may be composed of one or more layers. The phosphor layer 30 may contain a diffusing agent as necessary.

  Here, at least one type of phosphor that absorbs light from the light emitting element 20 having an emission peak wavelength of 380 nm to 430 nm and has an emission peak wavelength of 550 nm to 780 nm or a combination thereof is used. Here, red is mainly emitted as the emission color of the phosphor. The phosphor has only an emission peak wavelength at 550 nm to 780 nm and is not limited to one having an emission spectrum at 550 nm to 780 nm. In particular, those having an emission peak wavelength in the range from 610 nm to 680 nm are preferred, and those having an emission peak wavelength in the range from 610 nm to 650 nm are more preferred. Since the visibility decreases as it reaches a wavelength longer than 555 nm with a peak at about 555 nm, it is necessary to use a phosphor having an emission peak wavelength at 610 nm to 650 nm, which has a relatively high visibility in the red region. It is because it is preferable for improvement.

The average particle diameter of the phosphor is not particularly limited and can be appropriately selected depending on the purpose and the like. The average particle diameter of the phosphor is preferably 1 μm or more and 20 μm or less, and more preferably 5 μm or more and 15 μm or less from the viewpoint of light emission efficiency.
When the volume of the entire phosphor particles contained in the resin is the same, the particle surface area increases as the particle size decreases, and the light emitted from the phosphor particles is easily scattered by other phosphor particles, resulting in light extraction efficiency. Decreases. On the other hand, as the particle size increases, scattering is reduced and light extraction efficiency is increased, but the particle surface area is reduced, the amount of light emitted from the phosphor is reduced, and the amount of light that is not wavelength-converted is increased. Since the light reaching the phosphor layer 30 without wavelength conversion is returned again to the phosphor layer 30 side by the reflective film 40, the scattering of the particle surface is suppressed by increasing the particle size of the phosphor particles. Wavelength conversion of the first light from the light emitting element 20 can be performed efficiently. Therefore, in the light emitting device 100, the wavelength of the first light of the light emitting element 20 can be efficiently converted and the light extraction efficiency can be improved by increasing the particle diameter of the phosphor particles.

  In addition, the average particle diameter of the phosphor particles in the present specification refers to the average particle diameter of secondary particles formed by agglomerating primary particles. The average particle diameter (median diameter) of the secondary particles can be measured by, for example, a laser diffraction particle size distribution measuring device (product name: MASTER SIZER 3000, manufactured by MALVERN).

  The thickness of the phosphor layer 30 is preferably 30 μm to 150 μm, and more preferably 50 μm to 120 μm. Thereby, the amount of the second light lost due to the scattering in the phosphor layer 30 can be reduced, and the amount of the second light emitted from the phosphor layer 30 can be increased.

As the phosphor, a nitride phosphor, an oxide phosphor, a fluoride phosphor, a sulfide phosphor, or the like can be used.
The nitride-based phosphor is activated by at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Lu. At least one selected from the group consisting of C, Si, Ge, Sn, Ti, Zr, and Hf, and at least one group II element selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn. A phosphor containing the above Group IV element and N. O may be contained in the composition of the nitride phosphor.

Specific examples of the nitride-based phosphor include a general formula L _X M _Y N _{((2/3) X + (4/3) Y)} : R or L _X M _Y O _Z N _{((2/3) X + (4/3) Y- (2/3) Z)} : R (L is at least one Group II element selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn. M. Is at least one group IV element selected from the group consisting of C, Si, Ge, Sn, Ti, Zr, and Hf, and R is Y, La, Ce, Pr, Nd, Sm, Eu, And at least one rare earth element selected from the group consisting of Gd, Tb, Dy, Ho, Er, and Lu. X, Y, and Z are 0.5 ≦ X ≦ 3, 1.5 ≦ Y ≦ 8, 0 <Z ≦ 3)).

More specific examples of nitride-based phosphors include SCASN-based phosphors represented by (Sr, Ca) AlSiN ₃ : Eu and CASN-based phosphors represented by CaAlSiN ₃ : Eu. it can.
In addition to nitride phosphors, KSF (K ₂ SiF ₆ : Mn) phosphors, sulfide phosphors, and the like can be used.

  The example in which the phosphor layer 30 is formed by printing the translucent resin paste containing the phosphor particles has been described above. However, the phosphor layer 30 may be formed by depositing a translucent material such as glass or inorganic so as to include the phosphor. Further, although the phosphor layer 30 is shown in direct contact with the surface of the reflective film 40, the phosphor layer 30 is not necessarily in direct contact with the surface of the reflective film 40, and other adhesives and the like are used. It may be joined via a member. For example, a plate-like phosphor plate may be formed by pressure bonding, fusing, sintering, adhesion with an organic adhesive, or adhesion with an inorganic adhesive such as low-melting glass.

[Reflective film]
As the reflective film 40, it is preferable to use a dielectric multilayer film having high selectivity. Here, high selectivity means that the reflectance in the reflection wavelength band is high, the transmittance in the transmission wavelength band is high, and the change in reflectance or transmittance is steep between the reflection wavelength band and the transmission wavelength band. Say.

  The dielectric multilayer film is a reflective film in which two first dielectric layers 41 and second dielectric layers 42 having different refractive indexes are alternately and periodically formed with a thickness of λ / 4. Here, λ is a peak wavelength in a wavelength region to be reflected, and is an in-medium wavelength in each dielectric material. Theoretically, this dielectric multilayer film has a higher reflectivity as the refractive index difference between the two first dielectric layers 41 and the second dielectric layer 42 is larger, and as the number of cycles formed alternately is larger. It is known to be obtained. However, if the difference in refractive index between the two first dielectric layers 41 and the second dielectric layer 42 is too large or the number of periods is too large, the reflectivity rapidly decreases on both sides of the reflection peak wavelength λ (wavelength The wavelength dependence of the reflectance increases, and it becomes difficult to stably obtain the desired reflectance in the desired wavelength range. Therefore, in the dielectric multilayer film, each refractive index and refractive index difference between the first dielectric layer 41 made of a dielectric material having a high refractive index and the second dielectric layer 42 made of a dielectric material having a low refractive index are alternately arranged. The number of periods to be formed is appropriately set so that a desired reflectance is stably obtained in a desired wavelength range.

  Specifically, the first refractive index of the first dielectric layer 41 having a high refractive index is set, for example, in the range of 1.5 to 3.0, and preferably in the range of 2.0 to 2.6. Is set. The second refractive index of the second dielectric layer 42 having a low refractive index is set, for example, in the range of 1.0 to 1.8, and preferably in the range of 1.2 to 1.6. . Further, the number of periods in which the first dielectric layer 41 and the second dielectric layer 42 are alternately formed is set in a range of 1 to 20, for example, and preferably in a range of 1 to 5. The difference between the first refractive index and the second refractive index is preferably 0.3 or more, more preferably 0.5 or more, and even more preferably 0.7 or more.

The dielectric material constituting the first dielectric layer 41 can be selected from, for example, TiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and Zr ₂ O ₅ . The dielectric material composing the second dielectric layer 42 can be made of, for example, a material selected from SiO ₂ , Al ₂ O ₃ and SiON.

[Translucent member]
The translucent member 50 is provided with the reflective film 40 and the phosphor layer 30 on one surface, and supports the reflective film 40 and the phosphor layer 30. As the translucent member 50, a plate-like body made of a translucent material such as glass or resin can be used. As the glass, for example, borosilicate glass or quartz glass can be selected. Moreover, as resin, it can select from a silicone resin and an epoxy resin, for example. The thickness of the translucent member 50 should just be the thickness which can provide sufficient mechanical strength to the fluorescent substance layer 30, without the mechanical strength in a manufacturing process falling. Further, the light transmissive member 50 may contain a diffusing agent. As the diffusing agent, titanium oxide, barium titanate, aluminum oxide, silicon oxide, or the like can be used. Further, the upper surface of the translucent member 50 serving as the light emitting surface, that is, the surface opposite to the surface on which the reflective film 40 and the phosphor layer 30 are provided is not limited to a flat surface and has fine irregularities. May be. When the light emitting surface has irregularities, the emitted light from the light emitting surface is scattered, and it is possible to suppress uneven brightness and uneven color.

[Adhesive layer]
The adhesive layer 60 bonds the light emitting element 20 and the phosphor layer 30 together. The adhesive layer 60 is preferably made of a material that can guide the emitted light from the light emitting element 20 to the phosphor layer 30 without being attenuated as much as possible. Specific examples include organic resins such as epoxy resins, silicone resins, phenol resins, and polyimide resins, with silicone resins being preferred. The thinner the adhesive layer 60 is, the better. This is because when the adhesive layer is thin, loss of light transmitted through the adhesive layer can be reduced, heat dissipation can be improved, and the intensity of light emitted from the light emitting device can be increased.

  The adhesive layer 60 may exist not only between the light emitting element 20 and the phosphor layer 30 but also on the side surface of the light emitting element 20. Further, when a silicone resin is used for the binder of the phosphor layer 30, it is preferable to use a silicone resin for the adhesive of the adhesive layer 60. Since the refractive index difference between the phosphor layer 30 and the adhesive layer 60 can be reduced, incident light from the adhesive layer 60 to the phosphor layer 30 can be increased.

[resin]
As a material of the resin 70, an insulating material is preferably used. In order to ensure a certain level of strength, for example, a thermosetting resin, a thermoplastic resin, or the like can be used. More specifically, a phenol resin, an epoxy resin, a BT resin, PPA, a silicone resin, etc. are mentioned. In addition, a reflective member that hardly absorbs light from the light-emitting element 20 and has a large refractive index difference with respect to the base resin can be used as the base resin. Specifically, by dispersing at least one light diffusing material selected from the group consisting of zirconium oxide, yttrium oxide, aluminum oxide, aluminum hydroxide, barium carbonate, barium sulfate, magnesium oxide and magnesium carbonate, it is efficient. It can reflect light.
<Embodiment 2>

  A light-emitting device according to Embodiment 2 will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating an example of a light emitting device according to an embodiment. FIG. 10 is a spectrum diagram showing the powder reflectance of the (Sr, Ca) AlSiN3: Eu phosphor and the CaAlSiN3: Eu phosphor. The second embodiment is substantially the same as the first embodiment except that the phosphor layer 30 has a plurality of stacked phosphor layers. A description of the same parts as those in the first embodiment may be omitted.

In the phosphor layer 30, a CaAlSiN ₃ : Eu phosphor layer is disposed on the side closer to the light emitting element 20, and a (Sr, Ca) AlSiN ₃ : Eu phosphor layer is disposed on the far side. By arranging in this order, the luminous efficiency can be increased and a bright light emitting device can be provided as compared with the case where CaAlSiN ₃ : Eu phosphor and (Sr, Ca) AlSiN ₃ : Eu phosphor are dispersed. For example, the CaAlSiN ₃ : Eu phosphor has a higher reflectance than the (Sr, Ca) AlSiN ₃ : Eu phosphor in the vicinity of the emission wavelength of the light emitting element 20 of 440 nm to 480 nm, and thus the CaAlSiN ₃ : Eu phosphor layer. And (Sr, Ca) AlSiN ₃ : Eu phosphor layer reflected blue light from the light emitting element 20 can be returned to the CaAlSiN ₃ : Eu phosphor layer again, and the CaAlSiN ₃ : Eu phosphor emits light. It seems that it is amplifying. A (Sr, Ca) AlSiN ₃ : Eu phosphor having a lower reflectance and higher light absorption than the CaAlSiN ₃ : Eu phosphor in the vicinity of the emission wavelength of the light-emitting element 20 is disposed in the upper layer (Sr, Ca) AlSiN ₃ : Blue light that passes through the Eu phosphor layer can be reduced.

As a method for manufacturing the light emitting device 100, the reflective layer 40, which is a dielectric multilayer film alternately including dielectric layers having different refractive indexes, is formed on the translucent member 50, and (Sr, The phosphor layer 30 is formed in the order of Ca) AlSiN ₃ : Eu phosphor layer and CaAlSiN ₃ : Eu phosphor layer. The film thickness of the CaAlSiN ₃ : Eu phosphor layer and the (Sr, Ca) AlSiN ₃ : Eu phosphor layer is not particularly limited, but is, for example, about 100 μm.

The light emitting element 20 is arranged on the base 10 in advance. The adhesive layer 60 is applied to the upper surface of the light emitting element 20, and the phosphor layer 30 is disposed on the light emitting element 20 so that the light emitting surface of the light emitting element 20 faces the phosphor layer 30.
As described above, the light emitting device 100 can be easily manufactured.

Hereinafter, examples will be specifically described with reference to the drawings. However, the present embodiment is not limited to these examples. FIG. 3 is a diagram illustrating the reflectance with respect to the wavelength of the reflective film when light is vertically incident (incident angle is 0 °) in the light emitting device according to the first embodiment. FIG. 3 is a simulation. FIG. 4 is a diagram illustrating a shift of the chromaticity coordinate x depending on the directivity angle in the light emitting devices of the first embodiment, the second embodiment, and the comparative example 1. FIG. 5 is a diagram illustrating a shift of the chromaticity coordinate y depending on the directivity angle in the light emitting devices of the first embodiment, the second embodiment, and the comparative example 1. 6 is a diagram showing emission spectra of the light emitting devices according to Example 1, Example 2, and Comparative Example 1. FIG. 7 is a diagram showing an emission spectrum of the light emitting device according to Example 1, Example 2, and Comparative Example 1. FIG. FIG. 8 is a diagram showing the reflectance at the incident angle of the first light emitted from the light emitting element with respect to the reflective film. FIG. 9 is a diagram showing the reflectance at the incident angle of the first light emitted from the light emitting element with respect to the reflective film. FIG. 8 is a partial extract of FIG.
The light emitting devices of Example 1, Example 2, and Comparative Example 1 are manufactured. A description of the same part as the embodiment may be omitted.

As the light-emitting element 20 used in the light-emitting devices of Example 1, Example 2, and Comparative Example 1, nitride-based semiconductor light-emitting elements having emission peak wavelengths λp at about 403 nm, about 420 nm, and about 447 nm, respectively, are used. The translucent member 50 uses a glass plate having a thickness of 150 μm, and is a dielectric designed to reflect light having a wavelength shorter than 550 nm and transmit light having a wavelength longer than 550 nm on the glass plate. A reflective film 40 using a multilayer film (DBR reflective film) was formed. Specifically, the dielectric multilayer film includes a first dielectric layer 41 made of Nb ₂ O ₅ and a second dielectric layer 42 made of SiO _2, and the second dielectric layer 42 on the translucent member 50. The first dielectric layer 41, the second dielectric layer 42, and the first dielectric layer 41 were alternately stacked in this order by sputtering for 15.5 periods (31 layers in total).

The phosphor layer 30 is prepared by mixing a CASN-based phosphor particle represented by CaAlSiN ₃ : Eu with a silicone resin (KJR-9201 manufactured by Shin-Etsu Chemical Co., Ltd.) so as to have a predetermined weight%. The film was formed to a predetermined thickness by a printing method. The phosphor of the phosphor layer 30 used in Example 1, Example 2, and Comparative Example 1 has an emission peak wavelength of about 660 nm and an average particle diameter of 6.5 μm.

Then, the translucent member 50 on which the reflective film 40 and the phosphor layer 30 are formed is separated into pieces, and a silicone resin (Shin-Etsu Chemical Co., Ltd.) is placed on the light-emitting element 20 mounted on the base 10 (NJSW172A manufactured by Nichia Corporation). It joins by KJR-9200 made by an industrial company. Further, the side surface of the translucent member 50 except the upper surface of the translucent member 50, the phosphor layer 30, the light emitting element 20, and the inner bottom surface 16 and the inner side surface 17 of the recess 15 of the base 10 are covered with a resin 70. As the resin 70, a silicone resin (KJR-9023N manufactured by Shin-Etsu Chemical Co., Ltd.) containing a light diffusing material is used. A resin 70 is injected between the inner surface 17 of the recess 15 and the light emitting element 20 and the like, and the resin composition is cured by heating at about 150 ° C. for 4 hours.
Table 1 shows the light emission characteristics of the light emitting devices of Examples 1 and 2 and Comparative Example 1 manufactured as described above.

  In the light emitting devices of Example 1, Example 2, and Comparative Example 1, all emit light in a predetermined red color. FIG. 4 shows the light distribution chromaticity Δx and FIG. 5 shows the orientation chromaticity Δy of Examples 1, 2 and Comparative Example 1 at almost the same chromaticity point. Here, the light distribution chromaticities Δx and Δy represent deviations in chromaticity coordinates due to the directivity angle of the light emitting device with reference to the chromaticity coordinates in the front direction. In Comparative Example 1, both the orientation chromaticity Δx and Δy are shifted to the minus side by 0.01 or more at the directivity angles of 60 ° to 85 °, and the chromaticity coordinates are shifted in the direction of increasing blue. Compared to Comparative Example 1, in Examples 1 and 2, the chromaticity coordinate shift is small at the directivity angle of 60 ° to 85 °, and the light distribution chromaticity is improved. In addition, compared with Comparative Example 1, Example 2 and Example 1 have lower visibility, and thus it is more difficult to perceive color misregistration.

  Further, as shown in FIG. 8, the reflectance at each wavelength decreases to about half near the incident angle of 60 °, but sharply decreases only at the wavelength of 450 nm near the incident angle of 80 °. As a result, in Examples 1 and 2, the shift in light distribution chromaticity due to the directivity angle is kept small, but in Comparative Example 1, the shift in light distribution chromaticity increases as the incident angle increases. In addition, in the emission spectrum, compared with Comparative Example 1, Examples 1 and 2 have weaker peak wavelengths due to the light emitting elements. From this, it can be seen that in Examples 1 and 2, the reflectance of the DBR reflecting film depending on the incident angle is maintained, and the light emitted from the light emitting element is reflected.

  The light emitting device of the present embodiment can be used in a wide range of fields such as general lighting, in-vehicle lighting, ornamental lighting, warning lamps, and indicator lamps. For example, when a light emitting device used for a rear lamp, a brake lamp, or the like of a car is combined with a light emitting diode that emits near ultraviolet to blue light, for example, a nitride-based phosphor can be used.

DESCRIPTION OF SYMBOLS 10 Base 11 1st lead 12 2nd lead 13 Fixing part 14 Side wall 15 Recess 16 Inner bottom face 17 Inner side face 20 Light emitting element 21 Semiconductor laminated body 21a 1st semiconductor layer 21b Active layer 21c 2nd semiconductor layer 22 Substrate 30 Phosphor layer 40 reflective film 41 first dielectric layer 42 second dielectric layer 50 translucent member 60 adhesive layer 70 resin 100 light emitting device A incident angle

Claims (15)

A light-emitting element having a light-emitting surface that emits first light having an emission peak wavelength of 380 nm to 430 nm;
A phosphor layer that is disposed on the light emitting surface of the light emitting element and contains a phosphor that is excited by the first light and emits second light having a longer wavelength than the first light;
A reflective film provided on the phosphor layer and reflecting the first light and transmitting the second light;
In the reflection spectrum of the reflection film, the reflection film is a light emitting device in which a reflectance of light of 380 nm to 430 nm is 40% or more when an incident angle of the first light to the reflection film is 0 ° to 85 °.   2. The light emitting device according to claim 1, wherein the reflectance of light of 380 nm or more and 430 nm or less when the incident angle of the first light with respect to the reflection film is 0 ° to 45 ° is 90% or more.   3. The light emitting device according to claim 1, wherein when the incident angle between the first light and the reflective film is 0 °, the reflective film has a reflectance of 380 nm or more and 530 nm or less of 90% or more.   The light emitting device according to any one of claims 1 to 3, wherein the light emitting element has a relative intensity of 450 nm or less when a maximum intensity of an emission peak wavelength is 1.   The light emitting device according to any one of claims 1 to 4, wherein the phosphor has an emission peak wavelength in a range of 550 nm to 780 nm.   The light emitting device according to any one of claims 1 to 5, further comprising a translucent member provided on the reflective film.   The light emitting device according to any one of claims 1 to 6, further comprising a base, and the light emitting element is disposed on the base. The base has a recess having an inner bottom surface and an inner surface;
The light emitting element is disposed on the inner bottom surface of the recess of the base,
The light-emitting device according to claim 7, wherein a base material of the base is ceramic, and a resin is disposed in a concave portion of the base so as to be in contact with the light-emitting element and the translucent member.   The light emitting device according to claim 8, wherein an uppermost surface of the concave portion of the base is higher than a surface of the translucent member with respect to an inner bottom surface of the concave portion of the base.   10. The resin according to claim 1, wherein the resin includes at least one light diffusing material selected from the group consisting of zirconium oxide, yttrium oxide, aluminum oxide, aluminum hydroxide, barium carbonate, barium sulfate, magnesium oxide, and magnesium carbonate. A light-emitting device according to claim 1.   The chromaticity of light emitted from the light emitting device is (x = 0.645, y = 0.335), (x = 0.665, y = 0.335) in the xy chromaticity coordinate system of the CIE1931 chromaticity diagram. , (X = 0.735, y = 0.265), (x = 0.721, y = 0.259) are within a range surrounded by a quadrangle formed by connecting four points. A light-emitting device according to claim 1. The phosphor is at least one selected from a (Sr, Ca) AlSiN ₃ : Eu phosphor, a CaAlSiN ₃ : Eu phosphor, a K ₂ SiF ₆ : Mn phosphor, or a combination thereof. The light-emitting device according to any one of 11. A plurality of the phosphor layers are laminated, and a CaAlSiN ₃ : Eu phosphor layer is disposed on a side closer to the light emitting element, and a (Sr, Ca) AlSiN ₃ : Eu phosphor layer is disposed on a far side. The light emitting device according to any one of 11.   The light emitting device according to claim 1, wherein the reflective film is a dielectric multilayer film. A light emitting element that emits first light having an emission peak wavelength of 380 nm or more and 430 nm or less and is laminated in the order of a first semiconductor layer, an active layer, and a second semiconductor layer;
A phosphor layer that is disposed on the light emitting element and contains a phosphor that is excited by the first light and emits second light having a longer wavelength than the first light;
A reflective film provided on the phosphor layer and reflecting the first light and transmitting the second light;
A light emitting device having a reflectance of light of 380 nm or more and 430 nm or less in a range of −85 ° to + 85 ° in the direction of the reflection film with respect to the center of the active layer in a plan view of the light emitting element as 40% or more.

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