JP6428245B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device in which a light emitting element and a phosphor are combined.

  Light emitting diodes (LEDs) are useful as display lights, warning lights, display lights, and illumination lights. Various laser diodes (LDs) that combine phosphors with light-emitting diodes as well as light-emitting diodes have been proposed. Both light emitting diodes and lasers are semiconductor light emitting devices produced from III-V alloys such as gallium nitride (GaN). Various light emitting devices that emit light in white, light bulb color, orange color, etc. by combining this semiconductor light emitting element and phosphor have been developed. These light emitting devices that emit white light and the like are obtained by the principle of light color mixing. As a method for emitting white light, a method using a light emitting element that emits ultraviolet light and three types of phosphors that emit RGB light, a method that uses a light emitting element that emits blue light, and a phosphor that emits yellow light, etc. Is well known.

In addition to white light emitting devices, light sources of various colors including, for example, three primary colors of R (red), G (green), and B (blue) are required. For example, a light emitting device having a yellow hue with high saturation using a light emitting element that emits blue light and a phosphor that emits yellow light or the like is known (for example, see Patent Document 1).
On the other hand, a light emitting device composed of an excitation light source having an emission peak wavelength at 390 to 420 nm and various fluorescent materials has been proposed, and a good color tone can be realized (for example, see Patent Document 2).

JP 2007-234877 A JP 2002-171000 A

However, in a light-emitting device including a light-emitting element having an emission peak wavelength of 390 to 420 nm as an excitation light source, it is necessary to take measures for preventing leakage of light in the ultraviolet region in order to prevent an influence on the human body. Furthermore, since the excitation light source has a short wavelength, there is a concern that the resin that seals the light emitting element is adversely affected, leading to a decrease in reliability and a decrease in light emission luminance.
In addition to conventional light emitting devices that emit colors with high saturation, there is a need for light emitting devices that emit light of various intermediate colors that give a soft impression to the eye with low saturation.

  An object of one embodiment of the present invention is to provide a highly efficient light-emitting device that emits light of blue to green light that gives a soft impression to the eye with low saturation.

Specific means for solving the above-mentioned problems are as follows, and one embodiment according to the present invention includes the following aspects.
A light emitting device having an emission peak wavelength of 420 nm or more and 480 nm or less;
At least one phosphor selected from the group consisting of an alkaline earth metal aluminate phosphor represented by the following composition formula (1) and an oxynitride phosphor represented by the following composition formula (2); A light emitting device that emits blue to green light.
(Sr _1-x , Eu _x ) ₄ Al ₁₄ O ₂₅ (1)
In the formula, x satisfies 0.025 <x <0.4, and a part of Sr may be substituted with at least one element selected from the group consisting of Mg, Ca, Ba and Zn.
(Ba _1-y , Eu _y ) Si ₂ O ₂ N ₂ (2)
In the formula, y satisfies 0 <y <1.

  According to one embodiment of the present invention, it is possible to provide a highly efficient light-emitting device that emits light of blue to green color that gives a visually soft impression with low saturation.

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 chromaticity diagram which shows the chromaticity coordinate (CIE1931) of the light which the light-emitting device which concerns on this embodiment emits. It is a figure which shows the excitation spectrum of the fluorescent substance which concerns on this embodiment. It is a figure which shows the emission spectrum of the light-emitting device which concerns on this embodiment. It is a figure which shows the relationship between the relative intensity in the excitation spectrum of fluorescent substance AE which concerns on this embodiment, and the luminous efficiency of a light-emitting device. It is a figure which shows the emission spectrum of the light-emitting device which concerns on Examples 3-9. It is a figure which shows the emission spectrum of the light-emitting device which concerns on Examples 10-16. It is a figure which shows the emission spectrum of the light-emitting device which concerns on Examples 17-19. It is a figure which shows the chromaticity coordinate of the light which the light-emitting device which concerns on Examples 3-19 emits.

Hereinafter, a light-emitting device according to an embodiment of the present invention will be described using 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 does not specify the light emitting device as follows.
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 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.

<Light emitting device>
The light emitting device of this embodiment is represented by a light emitting element having an emission peak wavelength of 420 nm or more and 480 nm or less, an alkaline earth metal aluminate phosphor represented by the following composition formula (1), and the following composition formula (2). And a light emitting device that emits blue to green light, including at least one phosphor selected from the group consisting of oxynitride phosphors.
(Sr _1-x , Eu _x ) ₄ Al ₁₄ O ₂₅ (1)
In the formula, x satisfies 0.025 <x <0.4, and a part of Sr may be substituted with at least one element selected from the group consisting of Mg, Ca, Ba and Zn.
(Ba _1-y , Eu _y ) Si ₂ O ₂ N ₂ (2)
In the formula, y satisfies 0 <y <1.

A combination of a light emitting device having a specific emission peak wavelength and at least one phosphor selected from the group consisting of an alkaline earth metal aluminate phosphor and an oxynitride phosphor having a specific composition By configuring the light emitting device, light of blue to green color which gives a soft impression to the eye with low saturation can be emitted, and the light emission efficiency is further excellent.
The light emitting device appropriately selects the emission peak wavelength of the light emitting element, the amount of phosphor used, and the like, so that the first point (x = 0.148) in the chromaticity diagram of CIE1931 among the blue to green intermediate colors. , Y = 0.327), the second point (x = 0.079, y = 0.447), the third point (x = 0.069, y = 0.201) and the fourth point (x = 0.170, y = 0.006), and the intermediate color in the range surrounded by the first, the first straight line connecting the fourth point and the first point, the first point and the second point Arbitrary chromaticity in the area surrounded by the second straight line connecting, the third straight line connecting the second point and the third point, and the curve of the chromaticity diagram connecting the third point and the fourth point Coordinate light can be emitted. That is, in FIG. 3, the light emitting device can emit light having an arbitrary chromaticity in a region surrounded by three broken lines and a chromaticity diagram curve.

  The form of the light emitting device is not particularly limited, and can be appropriately selected from commonly used forms. As a type of the light emitting device, a shell type, a surface mount type, and the like can be given. 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. In addition, the surface mount type refers to the one formed by filling a light emitting element serving as a light source and a resin in a concave storage portion. Furthermore, as a form of the light emitting device, a light emitting device in which a light emitting element serving as a light source is mounted on a flat mounting substrate, and a sealing resin containing a phosphor is formed in a lens shape so as to cover the light emitting element, etc. Also mentioned.

An example of the light emitting device according to the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a light emitting device according to the present invention. This light-emitting device is an example of a surface-mounted light-emitting device.
A light emitting device 100 emits light on the short wavelength side of visible light (for example, 380 nm to 485 nm), and mounts the light emitting element 10 of a gallium nitride compound semiconductor having an emission peak wavelength of 420 nm or more and 480 nm or less, and the light emitting element 10. And a molded body 40. The molded body 40 has a first lead 20 and a second lead 30 and is integrally molded with a sealing resin that is a thermoplastic resin or a thermosetting resin. The molded body 40 has a recess having a bottom surface and side surfaces, and the light emitting element 10 is placed 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 via the wire 60. The light emitting element 10 is sealed with a sealing member 50. The sealing member 50 is preferably made of a thermosetting resin such as an epoxy resin, a silicone resin, an epoxy-modified silicone resin, or a modified silicone resin. The sealing member 50 includes at least one phosphor 70 selected from the group consisting of an alkaline earth metal aluminate phosphor that converts the wavelength of light from the light emitting element 10 and an oxynitride phosphor, a sealing resin, and the like. It contains.
FIG. 2 is a schematic sectional view showing another example of the light emitting device according to the present invention. The light emitting device has the light emission shown in FIG. 1 except that the phosphor 70 includes both an alkaline earth metal aluminate phosphor 71 and an oxynitride phosphor 72 for converting the wavelength of light from the light emitting element 10. It has the same configuration as the device.

[Light emitting element]
The light emission peak wavelength of the light emitting element is in the range of 420 nm or more and 480 nm or less. By using a light emitting element having an emission peak wavelength in this range as an excitation light source, it is possible to configure a light emitting device that emits mixed light of light from the light emitting element and fluorescence from the phosphor. Furthermore, since light emitted from the light emitting element to the outside can be used effectively, loss of light emitted from the light emitting device can be reduced, and a light emitting device with high efficiency and easy adjustment of chromaticity can be obtained. Can be obtained. Further, since no ultraviolet component is contained, deterioration of the components of the light-emitting device can be reduced, and a highly efficient light-emitting device with little adverse effect on the human body can be obtained.
The emission peak wavelength of the light emitting element may be, for example, 440 nm or more and 460 nm or less, and is preferably 445 nm or more and 455 nm or less.
The half width of the emission spectrum of the light emitting element is not particularly limited. The half width can be set to 30 nm or less, for example.

A semiconductor light emitting element is preferably used 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 strong against mechanical shock.
As the semiconductor light emitting device, for example, a semiconductor light emitting device that emits light in blue, green, or the like using a nitride semiconductor (In _X Al _Y Ga _1- XYN, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1). Can be used.

[Phosphor]
The phosphor is at least one selected from the group consisting of an alkaline earth metal aluminate phosphor represented by the composition formula (1) and an oxynitride phosphor represented by the following composition formula (2). Including. For example, the phosphor is contained in a sealing member to constitute a light emitting device.
The phosphor may include only one of the alkaline earth metal aluminate phosphor represented by the composition formula (1) and the oxynitride phosphor represented by the following composition formula (2), or both. You may go out. Further, each of the alkaline earth metal aluminate phosphor and the oxynitride phosphor may be one kind or plural kinds. When the light emitting device includes a plurality of types of phosphors, the content ratio of each phosphor is not particularly limited, and may be appropriately selected depending on the purpose and the like.
The light emitting device preferably includes at least one alkaline earth metal aluminate phosphor and at least one oxynitride phosphor. When the light-emitting device includes an alkaline earth metal aluminate phosphor and an oxynitride phosphor, the content ratio (alkaline earth metal aluminate phosphor / oxynitride phosphor) is, for example, 0. 01-99.

  The total phosphor content in the light emitting device can be appropriately selected according to the purpose and the like. For example, the total content of the phosphor can be 1 to 250 parts by weight with respect to 100 parts by weight of the sealing resin, and preferably 1 to 200 parts by weight.

(Alkaline earth metal aluminate phosphor)
The alkaline earth metal aluminate phosphor is represented by the following composition formula (1).
(Sr _1-x , Eu _x ) ₄ Al ₁₄ O ₂₅ (1)
In the formula, x satisfies 0.025 <x <0.4, and a part of Sr may be substituted with at least one element selected from the group consisting of Mg, Ca, Ba and Zn.
x preferably satisfies 0.038 <x <0.3 from the viewpoint of luminous efficiency. Furthermore, it is preferable that 0.05 <x <0.2. When a part of Sr is substituted with another element, the substitution rate is, for example, 0.1 to 50 mol%, and preferably 1 to 30 mol%.
The alkaline earth metal aluminate phosphors represented by the composition formula (1) can be used singly or in combination of two or more.

  The alkaline earth metal aluminate phosphor preferably has a relative intensity of 50% or more at an excitation wavelength of 450 nm, more preferably 60% or more, when the maximum intensity is 100% in the excitation spectrum. preferable. When the alkaline earth metal aluminate phosphor exhibits such an excitation spectrum, a light-emitting device having better luminous efficiency can be obtained.

The average particle diameter of the alkaline earth metal aluminate phosphor is not particularly limited and can be appropriately selected depending on the purpose and the like. The average particle size of the alkaline earth metal aluminate phosphor is preferably 11 μm or more and 30 μm or less, and more preferably 11 μm or more and 25 μm or less from the viewpoint of luminous efficiency.
The average particle size of the alkaline earth metal aluminate phosphor is a numerical value called the Fisher Sub Sieve Sizer's No., and the primary particle is measured by the air permeation method. The average value of the particle diameters of these was determined. For example, it is measured using a Fischer sub-sieve sizer (manufactured by Fischer).

  The alkaline earth metal aluminate phosphor represented by the composition formula (1) can be produced by a commonly used method. For example, reference can be made to the production methods described in the Fluorescent Handbook, Fluorescent Materials Association, edited by Ohmsha, 227-228. Moreover, you may select the fluorescent substance which has a desired characteristic from what is marketed.

(Oxynitride phosphor)
The oxynitride phosphor is represented by the following composition formula (2).
(Ba _1-y , Eu _y ) Si ₂ O ₂ N ₂ (2)
In the formula, y satisfies 0 <y <1, preferably satisfies 0 <y <0.2, and more preferably satisfies 0.005 <y <0.13.
The oxynitride phosphors represented by the composition formula (2) can be used singly or in combination of two or more.

  In composition formula (2), when y is in the above-described range, the relative intensity at 450 nm of the excitation spectrum becomes higher, so that a light-emitting device having better light emission efficiency can be obtained.

  The oxynitride phosphor represented by the composition formula (2) can be produced by a commonly used method. For example, reference can be made to the production method described in JP-A-2004-210921. Moreover, you may select the fluorescent substance which has a desired characteristic from what is marketed.

(Other phosphors)
The light emitting device may include other phosphors other than the alkaline earth metal aluminate phosphor and the oxynitride phosphor as necessary. Examples of other phosphors include nitride phosphors, oxynitride phosphors, sialon phosphors mainly activated by lanthanoid elements such as Eu and Ce; lanthanoid phosphors such as Eu, Mn, and the like Alkaline earth halogen apatite phosphors, alkaline earth metal borate phosphors, alkaline earth metal aluminate phosphors, alkaline earth silicates, alkaline earths mainly activated by transition metal elements of Sulfides, alkaline earth thiogallates, alkaline earth silicon nitrides, germanates; rare earth aluminates and rare earth silicates mainly activated by lanthanoid elements such as Ce; fluoride phosphors activated by Mn It is preferably at least one selected from organic and organic complexes mainly activated by a lanthanoid element such as Eu. Specifically, for example, (Ca, Sr, Ba) ₂ SiO ₄ : Eu, (Y, Gd) ₃ (Ga, Al) ₅ O ₁₂ : Ce, (Ca, Sr) ₂ Si ₅ N ₈ : Eu, CaAlSiN ₃ : Eu, (Ca, Sr) AlSiN ₃ : Eu, K ₂ SiF ₆ : Mn, etc. When the light-emitting device contains other phosphors, the content is not particularly limited as long as the light-emitting device emits blue to green light as a whole, and can be appropriately selected according to the purpose and the like.

[Sealing member]
The light emitting device can include, for example, a phosphor and a sealing resin, and can include a sealing member that seals the light emitting element. Examples of the sealing resin constituting the sealing member include thermoplastic resins and thermosetting resins. Specific examples of the thermosetting resin include modified silicone resins such as epoxy resins, silicone resins, and epoxy-modified silicone resins.
The sealing member may contain other components as needed in addition to the phosphor and the sealing resin. Examples of other components include fillers such as silica, barium titanate, titanium oxide, and aluminum oxide, light stabilizers, and colorants. When a sealing member contains another component, the content in particular is not restrict | limited, According to the objective etc., it can select suitably. For example, when a filler is included as another component, the content thereof can be 0.01 to 20 parts by weight with respect to 100 parts by weight of the sealing resin.

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

As a light emitting element, a nitride semiconductor light emitting element having an emission peak wavelength λp = 447 nm was prepared. Further, alkaline earth metal aluminate phosphors A to E shown in Table 1 and an oxynitride phosphor represented by the composition formula (2) were prepared.
The powder characteristics, emission characteristics, etc. of phosphors A to E are shown in Table 1, and the excitation spectrum is shown in FIG.

In Table 1, the average particle diameter is the Fischer sub-sieve sizer number, and was measured with Fischer sub-sieve sizer (manufactured by Fischer) using the air permeation method. Dm is the median particle diameter, and was measured with a Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) using an electric resistance method. As emission characteristics, chromaticity coordinates x and y of fluorescence due to excitation light of 460 nm and a Y value indicating emission intensity are shown. The Y value is shown as a relative value based on the phosphor E. Further, relative intensity (%) at 450 nm when the maximum intensity in each excitation spectrum is 100% is shown as excitation spectrum relative intensity.
Here, the phosphors A and B correspond to phosphors of comparative examples in which x in the composition formula (1) is 0.05 / 4 = 0.0125 and 0.1 / 4 = 0.025, respectively.

(Examples 1-3, Comparative Examples 1-2)
Preparation of Light-Emitting Device The prepared alkaline earth metal aluminate phosphor was prepared by using a silicone resin (shown in Table 2) such that the chromaticity coordinates of light emitted from the light-emitting device were around x = 0.150 and y = 0.175. (Shin-Etsu Chemical Co., Ltd.) was added at a content rate, 5% silica filler was added, mixed and dispersed, and then defoamed to obtain a phosphor-containing resin composition. Next, this phosphor-containing resin composition was injected and filled onto an LED package (emission peak wavelength 447 nm), and further heated at 150 ° C. for 4 hours to cure the resin composition. Each of the light emitting devices was manufactured through such a process.
In addition, the content rate of a fluorescent substance and a silica filler is a percentage of the weight reference | standard when resin is 100%.

  With respect to the obtained light emitting device, the light emission characteristics were measured and shown in Table 2. The emission spectrum is shown in FIG. Furthermore, FIG. 6 shows the relationship between the relative intensity at 450 nm and the luminous efficiency of the manufactured light emitting device when the peak intensity is 100% in the excitation spectra of the phosphors A to E.

From Table 2 and FIG. 6, it turns out that the luminous efficiency of Examples 1-3 is high compared with Comparative Examples 1-2. As shown in FIG. 4, in the phosphors A to E, the shape of the excitation spectrum changes depending on the amount of Eu, and the phosphors C to E can excite the phosphor more efficiently than the phosphors A to B. Therefore, high luminous efficiency can be obtained. That is, (Sr _1-x , Eu _x ) ₄ Al ₁₄ O ₂₅ (x satisfies 0.025 <x <0.4, and a part of Sr may be substituted with Mg, Ca, Ba, and Zn. A high-efficiency light-emitting device can be obtained when the relative intensity at 450 nm is 50% or more when the peak intensity is 100% in the excitation spectrum.

(Examples 4 to 9)
As the phosphor, the same phosphor E as in Example 3 was used, and a light emitting device was produced in the same manner as described above, except that the addition amount of the phosphor was changed as shown in Table 3, and evaluated in the same manner.
The emission spectrum is shown in FIG.

(Examples 10 to 16)
As the phosphor, an oxynitride phosphor of the composition formula (Ba _1-y , Eu _y ) Si ₂ O ₂ N ₂ (y = 0.02) is used, and the addition amount of the phosphor is as shown in Table 4. A light-emitting device was produced in the same manner as described above except that it was changed, and evaluated in the same manner.
The emission spectrum is shown in FIG.

(Examples 17 to 19)
As the phosphor, an alkaline earth metal aluminate phosphor E having a composition formula Sr _3.3 Al ₁₄ O ₂₅ : Eu _0.7 , and (Ba _1-y , Eu _y ) Si ₂ O ₂ N ₂ (y = 0.02) oxynitride-based phosphor mixed at a weight ratio of 1: 1, and the total addition ratio of the phosphor to the resin was changed as shown in Table 5 and was the same as above A light emitting device was manufactured and evaluated in the same manner.
The emission spectrum is shown in FIG.

In the partially enlarged chromaticity diagram shown in FIG. 10, points of chromaticity coordinates of light emitted from the light emitting devices manufactured in Examples 3 to 19 are shown. In Examples 3 to 19, since the light emitting element having the emission peak wavelength λp = 447 nm was used, the first point (x = 0.148, y = 0.327), the second point (x = 0.079, y = 0.447), light in the range surrounded by sequentially connecting points (x = 0.153, y = 0.021) related to the light emitting element (LED chip) of λp = 447 nm, the mixing ratio of the phosphor and the resin It can reproduce arbitrarily by adjusting the compounding ratio with respect to.
Further, in Examples 3 to 19, the light emitting element having the emission peak wavelength λp = 447 nm was used, but instead of this, by using the light emitting element having the emission peak wavelength λp = 420 nm to λp = 480 nm, the first point ( x = 0.148, y = 0.327), second point (x = 0.079, y = 0.447), third point for LED chip with λp = 480 nm (x = 0.068, y = 0.201) and the fourth point (x = 0.170, y = 0.006) related to the LED chip with λp = 420 nm can be arbitrarily reproduced.

  The light emitting device of the present embodiment can be used in a wide range of fields such as general lighting, in-vehicle lighting, display, fish collection lamp, ornamental lighting, warning lamp, indicator lamp, and liquid crystal backlight.

  10: light emitting element, 50: sealing member, 70: phosphor, 71: alkaline earth metal aluminate phosphor, 72: oxynitride phosphor, 100: light emitting device

Claims (3)

A light emitting device having an emission peak wavelength of 420 nm or more and 480 nm or less;
As a phosphor, it contains only an alkaline earth metal aluminate phosphor represented by the following composition formula (1) ,
In the CIE 1931 chromaticity diagram, the first point with chromaticity coordinates x = 0.148 and y = 0.327, the third point with chromaticity coordinates x = 0.069, y = 0.201 For the fourth point with chromaticity coordinates x = 0.170 and y = 0.006, a straight line connecting the fourth point and the first point, and a straight line connecting the first point and the third point And a light emitting device that emits light within a range surrounded by the curve of the chromaticity diagram connecting the third point and the fourth point .
(Sr _1-x , Eu _x ) ₄ Al ₁₄ O ₂₅ (1)
(Wherein x satisfies 0.025 <x <0.4, and a part of Sr may be substituted with at least one element selected from the group consisting of Mg, Ca, Ba and Zn) .) 2. The light emitting device according to claim 1, wherein the alkaline earth metal aluminate phosphor has a relative intensity of 50% or more at an excitation wavelength of 450 nm when the maximum intensity is 100% in an excitation spectrum. 3. The light emitting device according to claim 1, wherein an average particle diameter of the alkaline earth metal aluminate phosphor is 11 μm or more and 30 μm or less.