JP2011108672A - White light emitting apparatus and lighting fitting for vehicle using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white light emitting apparatus using a semiconductor light emitting element and a phosphor that is efficiently excited on light of the semiconductor light emitting element and emits light, capable of emitting a white light with a high luminescence intensity and having good temperature characteristics; and to provide a lighting fitting for vehicles using the white light emitting apparatus. <P>SOLUTION: There are provided the white light emitting apparatus and the lighting fitting for vehicles using the light emitting apparatus. The white light emitting apparatus comprises a semiconductor light emitting element having an emission spectrum peak in a wavelength range of 370 to 480 nm and two or more phosphors that are excited on light emitted from the semiconductor light emitting element to emit light. The apparatus includes, as the phosphors, a first phosphor represented by general formula Sr<SB>1-x-y</SB>Ba<SB>x</SB>Si<SB>2</SB>O<SB>2</SB>N<SB>2</SB>:Eu<SP>2+</SP><SB>y</SB>(wherein 0.3<x<1.0, 0.03<y<0.3, and x+y<1.0), and a second phosphor that is a cerium-activated YAG-based phosphor having a luminescence peak wavelength in a range of 510 to 600 nm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a white light emitting device used for a vehicular lamp, and a vehicular lamp using the white light emitting device.
Specifically, white light having high visibility within a chromaticity regulation range of a white light source used for a vehicle lamp using a semiconductor light emitting element and a phosphor that is efficiently excited and emitted by light of the semiconductor light emitting element. The present invention relates to a white light emitting device capable of emitting light with high light emission intensity and high color rendering properties, and a vehicular lamp using the white light emitting device.

In recent years, as a white light emitting device with long life and low power consumption, a semiconductor light emitting diode (LED) or a laser diode (LD) emitting blue light and a phosphor using these as an excitation light source are combined. White light-emitting devices configured to obtain white light as a combined spectrum obtained by additive color mixing of light emission obtained from the above are attracting attention, and the use thereof is used as a white light source for vehicle lamps, particularly vehicle headlamps. Is expected. (Patent Document 1)
Here, the white light source of the vehicular lamp is required to have an emission spectrum within a range of predetermined chromaticity coordinates (cx, cy) according to chromaticity regulation. For example, according to JIS: D5500, FIG. It is required to be within the range of the area A shown in the chromaticity diagram.
The region A is represented by the following formula.
<Chromaticity regulation of white light source for vehicle headlamps (JIS: D5500)>
Yellow direction cx ≦ 0.50
Blue direction cx ≧ 0.31
Green direction cy ≦ 0.44 and cy ≦ 0.15 + 0.64cx
Purple direction cy ≧ 0.05 + 0.75 cx and cy ≧ 0.382

As an example of a white light emitting device that can emit white light meeting such chromaticity regulations with high light emission intensity, an InGaN-based semiconductor light emitting element having an emission peak wavelength in a blue wavelength range (420 to 490 nm), 510 There is known a white light emitting device that realizes white light emission in combination with a cerium-activated yttrium aluminum garnet (YAG) -based yellow phosphor having an emission peak wavelength between ˜600 nm. (Patent Document 2)
Japanese Patent Publication No. 2004-095480 Japanese Patent No. 3503139

By the way, the chromaticity range that can be reproduced by a white light emitting device combining a semiconductor light emitting element that emits blue light and a yellow phosphor is the chromaticity coordinates of blue light emitted from the semiconductor light emitting element and the yellow light emitted from the phosphor. Can be approximately represented by a straight line connecting the chromaticity coordinates, and light having an arbitrary chromaticity coordinate on the straight line can be obtained by adjusting the emission intensity of the two.
A straight line L shown in the chromaticity diagram of FIG. 1 is an example of such a straight line, and a blue semiconductor light emitting element having an emission peak wavelength of 450 nm and chromaticity coordinates are P (cx = 0.43, cy = 0.54). It is a straight line which shows the chromaticity range reproducible with the white light-emitting device which combined yellow fluorescent substance which is.

Here, the visual sensitivity with which the human eye perceives brightness is about 20 times higher for yellow light than for blue light. Therefore, in the case of white light that is a mixture of blue light and yellow light, the luminous intensity is the same. However, white light with a lot of yellow light component feels brighter to human eyes. This means that the light of each chromaticity coordinate on the straight line L is felt brighter to the human eye when it has the same emission intensity, closer to the yellow phosphor side. Further, the chromaticity coordinate having the highest visibility within the range of the region A (the chromaticity regulation of the white light source of the vehicular lamp) is the intersection X between the yellow phosphor side boundary line of the region A and the straight line L.

Accordingly, when the high visibility of white light is pursued within the range of the region A (the chromaticity regulation of the white light source of the vehicular lamp), the coordinates of the intersection X are on the yellow phosphor side (X ′ side in FIG. 1). It is necessary to select the light emission color of the semiconductor light emitting element and the light emission color of the phosphor so as to be close to.
Specifically, when the emission peak wavelength of the semiconductor light emitting device is around 450 nm, the coordinates of the intersection X are in the range where the visibility is high, the dominant wavelength of the yellow phosphor is in the range of 575 nm to 590 nm. .

However, in the conventional white light emitting device combining a semiconductor light emitting element that emits blue light and a YAG phosphor, a YAG phosphor that has a high emission intensity within a dominant wavelength range of 575 nm to 590 nm is known. Therefore, it has been difficult to realize a white light emitting device capable of emitting white light with high luminous intensity with high emission intensity.

In the YAG yellow phosphor, it is known that the dominant wavelength of the emission spectrum is shifted to the longer wavelength side by mixing gadolinium.
Therefore, the inventors have a YAG-based phosphor represented by the general formula Y ₃ Al ₅ O ₁₂ : Ce that does not contain gadolinium (manufactured by Phosphor Technology (UK): QUM58 / F-U1, hereinafter Gd-free) Phosphor), and a phosphor represented by the general formula (Y, Gd) ₃ Al ₅ O ₁₂ : Ce mixed with gadolinium in this YAG-based phosphor (P46-Y3, manufactured by Kasei Optonics Co., Ltd., hereinafter Gd-containing fluorescence) When the emission characteristics of these phosphors were measured, the following results were obtained.

Table 1 shows the chromaticity coordinates (cx, cy), peak wavelength (nm), and dominant wavelength (nm) of each phosphor under 450 nm excitation.

FIG. 2 shows the emission spectrum (solid line) of the Gd-free phosphor and the emission spectrum (dotted line) of the Gd-containing phosphor.

From Table 1 and FIG. 2, it can be seen that the Gd-containing phosphor has a longer peak wavelength and dominant wavelength than the Gd-free phosphor.

The chromaticity diagram of FIG. 1 shows the chromaticity coordinates of the phosphor not containing Gd as P and the chromaticity coordinates of the phosphor containing Gd as P ′.
When the chromaticity coordinates are shifted from P to P ′ from the chromaticity coordinates of FIG. 1, the reproducible chromaticity range when combined with a blue semiconductor light emitting element having an emission peak wavelength of 450 nm is from a straight line L to a dotted line L ′. It can be seen that the intersection with the region A is shifted from X to X ′.
From this, in the region A, it is expected that the Gd-containing phosphor can realize a white light emitting device having higher visibility than the Gd-free phosphor.

However, according to the measurement results of the present inventors, it has been found that the Gd-containing phosphor has lower emission characteristics at high temperatures than the Gd-free phosphor phosphor.
Hereinafter, the measurement results will be described in detail.

FIG. 3 is a schematic view showing an apparatus for measuring a change in the light emission characteristic of the phosphor due to a change in temperature condition (hereinafter, temperature characteristic).
In the measuring apparatus 10 shown in FIG. 3, an opening 11a for sample setting is formed on the upper surface of an aluminum substrate 11, and a thermocouple 12 and a planar heater 13 located immediately below the opening are embedded in the aluminum substrate. The thermocouple 12 and the planar heater 13 are connected to a temperature controller.
A condensing lens 14 that emits excitation light and a light receiving quartz fiber 17 that receives light emitted from the phosphor are installed above the opening 11a.
A xenon lamp as an excitation light source is connected to the condenser lens 14 via a quartz fiber 15 and a spectroscope 16a.
A photomultiplier as a measuring instrument is connected to the light receiving quartz fiber 17 via a spectroscope 16b.

In the measuring apparatus 10 configured as described above, the temperature characteristics of each phosphor were measured as follows.
First, each phosphor 18 to be a sample was filled in the opening 11a, and the filling surface was smoothed with a squeegee or the like.
Next, the output of the planar heater 13 is adjusted by the temperature controller, and the temperature of the aluminum substrate 11 that changes in accordance with the output is fed back to the temperature controller via the thermocouple 12, and the temperature of the aluminum substrate is set to a predetermined temperature. Maintained.
The temperature of the aluminum substrate is regarded as the temperature of the phosphor 18, and after 10 minutes have passed since the temperature of the aluminum substrate reaches each temperature condition, the light of the xenon lamp (USHIO Inc .: UXL-150D-O) is used as the spectroscope. 16a (Horiba: H-20UV) is used to irradiate the phosphor 18 with excitation light from the condenser lens 14 as excitation light through the condenser lens 14, and the emitted phosphor light is received by the quartz fiber 17 for light reception and the spectrometer 16b. (Horiba Seisakusho: H-20VIS) was measured with Photomaru (manufactured by Hamamatsu Photonics: R955-07).

FIG. 4 shows temperature characteristics of the Gd-containing phosphor and the Gd-free phosphor under 450 nm excitation.
In addition, the vertical axis | shaft of the graph in FIG. 4 has shown the integral light emission intensity | strength in each temperature condition as a ratio which makes the integral light emission intensity | strength in 30 degreeC conditions 100% about each fluorescent substance.

From FIG. 4, the Gd-containing phosphor and the Gd-free phosphor both have lower integrated emission intensity as the temperature conditions become higher, but the Gd-containing phosphor is less in comparison with the Gd-free phosphor. The retention rate is low, and under 200 ° C., the Gd-free phosphor has a retention rate of about 80%, whereas the Gd-containing phosphor has a retention rate of about 50%, which is about 1.6 times or more. It can be seen that there is a difference in emission intensity.

From the above, it has been found that the dominant wavelength of the emission spectrum of the Gd-containing phosphor shifts to the longer wavelength side due to the influence of gadolinium, but the emission characteristics at high temperatures deteriorate.
For this reason, the Gd-containing phosphor requires a large current, and thus is not suitable for use in a high-output white light-emitting device that generates a large amount of heat, and it is difficult to realize a high-output white light-emitting device using the Gd-containing phosphor. there were.

The present invention has been made in view of the above circumstances, and an object thereof is a white light emitting device using a semiconductor light emitting element and a phosphor that is efficiently excited by the light of the semiconductor light emitting element to emit light. A white light emitting device capable of emitting white light within a chromaticity stipulated range of a white light source used for a vehicular lamp at a high emission intensity and having good temperature characteristics that do not deteriorate the light emission characteristics even at high temperatures; And it aims at providing the vehicular lamp using this.

As a result of repeated studies to solve the above problems, the present inventors have obtained a general formula of Sr _1-xy Ba _x Si ₂ O ₂ N ₂ : Eu ²⁺ _y (where x is 0.25 <x < 1.0 and y are 0.03 <y <0.3, and x + y is in the range of 0.3 <x + y <1.0), and the phosphor is efficiently excited in the wavelength range of 370 to 480 nm. Newly discovered that visible light containing a large amount of yellow component emits light with high emission intensity and that the light emission characteristics do not deteriorate even at high temperatures, and a white light emitting device is configured using this phosphor. Thus, the present invention has been completed.

That is, the white light emitting device according to claim 1 of the present invention is a white light emitting device used for a vehicle lamp, and includes a semiconductor light emitting element having an emission spectrum peak in a wavelength region of 370 to 480 nm, and the semiconductor light emitting element. In a white light emitting device including at least two kinds of phosphors that are excited by emitted light and emit visible light, the phosphors have the general formula Sr _1-xy Ba _x Si ₂ O ₂ N ₂ : Eu ²⁺ _y Where x is 0.25 <x <1.0, y is 0.03 <y <0.3 x + y is in the range of 0.3 <x + y <1.0. And a second phosphor which is a cerium activated yttrium aluminum garnet (YAG) phosphor having an emission peak wavelength between 510 and 600 nm.

Here, the specific chemical composition of the first phosphor is not particularly limited as long as it is a phosphor represented by the general formula, but from the viewpoint of chromaticity of a light emitting device, the general phosphor It is preferable to use a first phosphor in which x in the formula is in a range of 0.425 ≦ x ≦ 0.750, y is in a range of 0.150 ≦ y ≦ 0.200, and x + y is in a range of 0.575 ≦ x + y ≦ 0.950. preferable.

The second phosphor is not particularly limited as long as it is a cerium-activated YAG phosphor having an emission peak wavelength between 510 and 600 nm, but it does not contain gadolinium. If the phosphor is a phosphor, there is little decrease in temperature characteristics when the temperature is increased, and a white light emitting device that fully utilizes its excellent light emission characteristics can be obtained.

The dominant wavelength of the emission spectrum of the first phosphor and the second phosphor is not particularly limited, but is white that emits warm white light with high visual sensitivity and a color temperature of 3000K to 4000K. In order to obtain a light emitting device, the dominant wavelength of the emission spectrum of the first phosphor is in the wavelength range of 570 to 590 nm, and the dominant wavelength of the emission spectrum of the second phosphor is in the wavelength range of 565 to 573 nm. The white light emitting device according to claim 1, wherein the white light emitting device is provided.

For the same reason, the peak wavelength of the emission spectrum of the first phosphor is in the wavelength range of 565 to 610 nm, and the peak wavelength of the emission spectrum of the second phosphor is in the wavelength range of 540 to 560 nm. It is more preferable.

The peak wavelength and half value of the synthetic spectrum of the first phosphor and the second phosphor are not particularly limited, but from the viewpoint of color rendering properties of the white light emitting device, the peak wavelength is 570 to 585 nm. It is preferable that the full width at half maximum is 80 nm or more.

The method for producing the phosphor is not particularly limited, but as the method for producing the phosphor, a mixture of SrCO ₃ , BaCO ₃ , SiO ₂ and Eu ₂ O ₃ is primarily fired in a reducing atmosphere. Luminous intensity in the yellow to orange wavelength region is obtained by using the europium-activated orthosilicate as a precursor and firing the mixture of this precursor with Si ₃ N ₄ and NH ₄ Cl in a reducing atmosphere. A phosphor having

The semiconductor light emitting device is not particularly limited as long as it has an emission spectrum peak in a wavelength range of 370 to 480 nm. From the viewpoint of the excitation wavelength range of the phosphor, the emission spectrum peak is from 430 nm to 430 nm. It is preferably in the wavelength region of 470 nm, and a suitable example is an InGaN-based LED having good light emission characteristics in the wavelength region near 450 nm.

The vehicular lamp according to claim 9 of the present invention is characterized in that the white light emitting device is used as a light source.

By configuring the light-emitting device as described above, it is possible to emit white light within a chromaticity stipulated range of a white light source used in a vehicle lamp with high light emission intensity, and the light emission characteristics deteriorate even at high temperatures. A white light emitting device having good temperature characteristics and a vehicle lamp using the same can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following examples.

FIG. 5 is a schematic cross-sectional view showing an embodiment of the white light emitting device of the present invention.
In the white light emitting device 20 shown in FIG. 5, a pair of electrodes 22 a (anode) and 22 b (cathode) are formed on a substrate 21. A semiconductor light emitting element 23 is fixed on the electrode 22 a by a mount member 24. The semiconductor light emitting element 23 and the electrode 22 a are energized by the mount member 24, and the semiconductor light emitting element 23 and the electrode 22 b are energized by the wire 25. A fluorescent layer 26 is formed on the top 23 of the semiconductor light emitting device.

The substrate 21 is preferably formed of a material having no electrical conductivity but high thermal conductivity. For example, a ceramic substrate (aluminum nitride substrate, alumina substrate, mullite substrate, glass ceramic substrate), a glass epoxy substrate, or the like is used. be able to.

The electrodes 22a and 22b are conductive layers formed of a metal material such as gold or copper.

The semiconductor light-emitting element 23 is an example of a light-emitting element used in the white light-emitting device of the present invention. For example, an LED or LD that emits ultraviolet light or short-wavelength visible light can be used. Specific examples include InGaN-based compound semiconductors. The emission wavelength range of the InGaN-based compound semiconductor varies depending on the In content. When the In content is large, the emission wavelength becomes a long wavelength, and when it is small, the wavelength tends to be a short wavelength.

The mounting member 24 is, for example, a conductive adhesive such as silver paste or gold-tin eutectic solder, and the lower surface of the semiconductor light emitting element 23 is fixed to the electrode 22a. The electrode 22a is electrically connected.

The wire 25 is a conductive member such as a gold wire, and is bonded to the upper surface side electrode of the semiconductor light emitting element 23 and the electrode 22b by, for example, ultrasonic thermocompression bonding, and electrically connects both.

In the fluorescent layer 26, a phosphor described later is sealed in a film shape covering the upper surface of the semiconductor light emitting element 23 with a binder member. For example, the phosphor layer 26 is prepared by preparing a phosphor paste in which a phosphor is mixed in a liquid or gel binder member, and then applying the phosphor paste on the upper surface of the semiconductor light emitting element 23. It can be formed by curing the binder member of the phosphor paste.
As the binder member, for example, a silicone resin or a fluorine resin can be used.

The first phosphor used in the white light emitting device of the present invention has a general formula Sr _1-xy Ba _x Si ₂ O ₂ N ₂ : Eu ²⁺ _y (where x is 0.25 <x <1.0). , Y is 0.03 <y <0.3 x + y is in the range of 0.3 <x + y <1.0).
This first phosphor is produced, for example, by firing a mixed powder of SrCO ₃ , BaCO ₃ , SiO ₂ , Eu ₂ O _{3 in} a reducing atmosphere and using europium-activated orthosilicate as a precursor. This precursor can be pulverized, added with Si ₃ N ₄ and NH ₄ Cl, and fired in a reducing atmosphere.

The second phosphor used in the white light emitting device of the present invention is a cerium-activated yttrium aluminum garnet (YAG) phosphor having an emission peak wavelength between 510 and 600 nm. Y _1-xy , Gd _x ) Al ₅ O ₁₂ : Ce _y (where x is in the range of 0 ≦ x <0.9 and y is in the range of 0 <y <0.1). Etc.
This second phosphor can be obtained, for example, by firing a mixed powder of Al ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ , and CeO _{2 in} the air atmosphere.

In addition to the first phosphor and the second phosphor, one or more types of phosphors having emission characteristics different from these can be mixed in the phosphor layer 26. The chromaticity of white light obtained from the white light emitting device can be adjusted by changing the blending amount of these phosphors.

Further, the phosphor layer 26 can be mixed with substances other than phosphors having various physical properties. For example, the refractive index of the fluorescent layer 26 can be increased by mixing the fluorescent layer 26 with a material having a higher refractive index than that of a binder member such as a metal oxide, a fluorine compound, or a sulfide. As a result, it is possible to reduce the total reflection that occurs when the light generated from the semiconductor light emitting element 23 enters the fluorescent layer 26 and to improve the efficiency of capturing excitation light into the fluorescent layer 26. Furthermore, the refractive index can be increased without reducing the transparency of the fluorescent layer 26 by making the particle size of the mixed substance nano-sized.
In addition, white powder having an average particle size of about 0.3 to 2 μm, such as alumina, zirconia, or titanium oxide, can be mixed in the fluorescent layer 26 as a light scattering agent. Thereby, unevenness in luminance and chromaticity of the light emitting surface can be prevented.

In the white light emitting device configured as described above, when a driving current is applied to the electrodes 22a and 22b, the semiconductor light emitting element 23 is energized, and the semiconductor light emitting element 23 has a specific wavelength including blue light toward the fluorescent layer 26. Irradiate area light. A part of this light is used to excite the phosphor in the fluorescent layer 26, and the remaining light passes through the fluorescent layer 26 and is directly irradiated to the outside. The phosphor is excited by light from the semiconductor light emitting element 23 and emits light in a specific wavelength range. White light can be obtained by additively mixing the light from the semiconductor light emitting element 23 that has passed through the fluorescent layer 26 and the light emitted from the phosphor.

The light-emitting device configured as described above will be described in more detail with reference to the following examples. However, the following description of the light-emitting device, the manufacturing method, the chemical composition of the phosphor, and the like will be given below. The embodiment is not limited in any way.

First, the phosphor used in the light emitting device of this example will be described in detail.

<First phosphor 1>
A phosphor represented by Sr _0.05 Ba _0.75 Si ₂ O ₂ N ₂ : Eu ²⁺ _0.2 .
First, 0.114 g of SrCO ₃ , 2.277 g of BaCO ₃ , 0.541 g of Eu ₂ O ₃ and 0.462 g of SiO ₂ were weighed, and each raw material was put in an alumina mortar. The mixture was pulverized for 20 minutes, the mixture was put in an alumina crucible, the lid was closed, and the mixture was calcined in a reducing atmosphere H ₂ / N ₂ (5/95), 1100 ° C. for 3 hours, and the precursor Sr _0.1 Ba1 _{. 5} SiO ₄ : Eu ²⁺ _0.4 was obtained.
Next, 2.451 g of the above precursor, 0.935 g of Si ₃ N ₄ and 0.034 g of NH ₄ Cl as a flux were weighed, and each raw material was put in an alumina mortar and mixed and ground for about 20 minutes. The first phosphor 1 was obtained by placing the lid in an alumina crucible and firing the lid at a reducing atmosphere H ₂ / N ₂ (5/95), 1200 to 1400 ° C. for 6 hours.

<First phosphor 2>
A phosphor represented by Sr _0.425 Ba _0.425 Si ₂ O ₂ N ₂ : Eu ²⁺ _0.15 .
In the production of this phosphor, first, 1.321 g of SrCO ₃ , 1.766 g of BaCO ₃ , 0.556 g of Eu ₂ O ₃ and 0.632 g of SiO ₂ were weighed, and each raw material was put in an alumina mortar. The mixture was pulverized for 20 minutes, the mixture was put in an alumina crucible, the lid was closed, and the mixture was calcined in a reducing atmosphere H ₂ / N ₂ (5/95), 1100 ° C. for 3 hours, and the precursor Sr _0.85 Ba _{0. 85} SiO ₄ : Eu ²⁺ _0.3 was obtained.
Next, 3.289 g of the above precursor, 1.403 g of Si ₃ N ₄ and 0.047 g of NH ₄ Cl as a flux were weighed, each raw material was placed in an alumina mortar and mixed and ground for about 20 minutes. An alumina crucible was put on the lid and the mixture was fired at a reducing atmosphere H ₂ / N ₂ (5/95) at 1200 to 1400 ° C. for 6 hours to obtain a first phosphor 2.

<First phosphor 3>
A phosphor represented by Sr _0.225 Ba _0.675 Si ₂ O ₂ N ₂ : Eu ²⁺ _0.1 .
Production of the phosphor, first, 0.511 g of SrCO _3, 2.049g of BaCO _3, 0.271 g of _Eu 2 _{O 3,} a SiO ₂ 0.462 g were weighed, approximately putting the raw materials into an alumina mortar The mixture was pulverized for 20 minutes, the mixture was put in an alumina crucible, the lid was closed, and the mixture was calcined in a reducing atmosphere H ₂ / N ₂ (5/95), 1100 ° C. for 3 hours, and the precursor Sr _0.45 Ba1 _{. 35} SiO ₄ : Eu ²⁺ _0.20 was obtained.
Next, 2.315 g of the precursor, 0.935 g of Si ₃ N ₄ and 0.03 g of NH ₄ Cl as a flux were weighed, each raw material was put in an alumina mortar and mixed and ground for about 20 minutes. An alumina crucible was put on the lid, and it was fired at a reducing atmosphere H ₂ / N ₂ (5/95), 1200 to 1400 ° C. for 6 hours to obtain the first phosphor 3.

<Reference phosphor 1>
A phosphor represented by Sr _0.93 Si ₂ O ₂ N ₂ : Eu ²⁺ _0.07 .
In the production of this phosphor, first, 3.051 g of SrCO ₃ , 0.274 g of Eu ₂ O ₃ and 0.668 g of SiO ₂ were weighed, and each raw material was put in an alumina mortar and mixed and ground for about 20 minutes. The mixture was put in an alumina crucible, covered, and calcined in a reducing atmosphere H ₂ / N ₂ (5/95) in an electric furnace at 1100 ° C. for 3 hours to obtain a precursor Sr _1.86 SiO ₄ : Eu ²⁺ _0.14 . It was.
Next, 2.763 g of the precursor, 1.403 g of Si ₃ N ₄ and 0.04 g of NH ₄ Cl as a flux were weighed, each raw material was put in an alumina mortar and mixed and ground for about 20 minutes. An alumina crucible was put on the lid and the mixture was baked at a reducing atmosphere H ₂ / N ₂ (5/95), 1200 to 1400 ° C. for 6 hours to obtain a reference phosphor 1.

<Reference phosphor 2>
A phosphor represented by Sr _0.67 Ba _0.25 Si ₂ O ₂ N ₂ : Eu ²⁺ _0.08 .
Production of the phosphor, first, 0.152 g of SrCO _3, 0.759 g of BaCO _3, 0.217 g of _Eu 2 _{O 3,} a SiO ₂ 0.462 g were weighed, approximately putting the raw materials into an alumina mortar The mixture was pulverized for 20 minutes, the mixture was put in an alumina crucible, the lid was closed, and the mixture was calcined in a reducing atmosphere H ₂ / N ₂ (5/95), 1100 ° C. for 3 hours, and the precursor Sr _1.34 Ba _{0. 5} SiO ₄ : Eu ²⁺ _0.16 was obtained.
Next, 2.017 g of the precursor, 0.935 g of Si ₃ N ₄ and 0.03 g of NH ₄ Cl as a flux were weighed, each raw material was put in an alumina mortar and mixed and ground for about 20 minutes. A lid was placed in an alumina crucible, and firing was performed in a reducing atmosphere H ₂ / N ₂ (5/95) at 1200 to 1400 ° C. for 6 hours to obtain a reference phosphor 2.

<Second phosphor 1>
As the second phosphor 1, a phosphor represented by Y ₃ Al ₅ O ₁₂ : Ce (manufactured by Phosphor Technology (UK): QUM58 / F-U1) was used.
This phosphor is an example of a YAG phosphor that does not contain gadolinium.

<Second phosphor 2>
As the second phosphor 2, a phosphor represented by (Y, Gd) ₃ Al ₅ O ₁₂ : Ce (P46-Y3, manufactured by Kasei Optonix) was used.
This phosphor is an example of a YAG-based phosphor containing gadolinium.

<Mixed phosphor 1>
A mixed phosphor in which the first phosphor 1 and the second phosphor 1 are mixed so that the weight ratio of the first phosphor 1 and the second phosphor 1 is 1: 2.5. 1 was produced.

<Evaluation results of emission characteristics of phosphor>
Hereinafter, various emission characteristics under 450 nm excitation measured for the first phosphors 1 to 5, the second phosphors 1 to 2, and the mixed phosphor 1 will be described in detail.

FIG. 6 shows the excitation spectrum of the first phosphor 1.
From FIG. 6, it can be seen that the first phosphor 1 has a broad excitation spectrum peak at 400 to 470 nm.
From this, it can be seen that the first phosphor 1 is efficiently excited by the light of the semiconductor light emitting element having the emission spectrum peak in the wavelength range of 370 to 480 nm and can emit light.

Table 1 shows the integrated emission intensity ratio, chromaticity coordinates (cx, cy), and dominant wavelength (nm) of each phosphor under 450 nm excitation.
The integrated emission intensity ratio is shown as a relative value when the integrated emission intensity of the second phosphor 2 is 100.

From Table 2, the first phosphors 1 to 3 all show an integrated emission intensity stronger than that of the second phosphor 2 (Gd-containing phosphor), and the chromaticity coordinates are cx = 0.47-0. 52, cy = 0.47 to 0.51.
The first phosphors 1 to 3 and the reference phosphors 1 to 2 are all represented by the general formula Sr _1-xy Ba _x Si ₂ O ₂ N ₂ : Eu ²⁺ _y (where x is 0. 25 <x <1.0, y is 0.03 <y <0.3, and x + y is in the range of 0.3 <x + y <1.0). It can be seen that the dominant wavelength of the emission spectrum is longer than that of the second phosphor 1 (Gd-free phosphor).

FIG. 7 shows the emission spectrum (dotted line) of the first phosphor 1 under 450 nm excitation, the emission spectrum (solid line) of the first phosphor 2, the emission spectrum (dotted line) of the first phosphor 3, and The emission spectrum (two-dot chain line) of the second phosphor 1 (Gd-free phosphor) is shown.
In addition, the vertical axis | shaft of the graph in FIG. 7 shows the relative light emission intensity of each fluorescent substance.

From FIG. 7, the peak wavelengths of the emission spectra of the respective phosphors are 585 to 595 nm for the first phosphor 1, 565 to 580 nm for the first phosphor 2, 565 to 580 nm for the first phosphor 3, The second phosphor 1 (Gd-free phosphor) is in the wavelength range of 540 to 550 nm, and the first phosphors 1 to 3 all have a longer emission spectrum peak wavelength than the second phosphor 1. I understand that there is.

Further, it can be seen from FIG. 7 that the emission spectra of the first phosphors 1 to 3 have no noticeable difference in waveform, and the full widths at half maximum are 80 to 110.

In FIG. 8, the emission spectrum (dotted line) of the 1st fluorescent substance 1 under 450 nm excitation, the emission spectrum (one-dot chain line) of the 2nd fluorescent substance 1, and the emission spectrum (solid line) of the mixed fluorescent substance 1 are shown.
In addition, the vertical axis | shaft of the graph in FIG. 8 shows the relative light emission intensity | strength of each fluorescent substance.

From FIG. 8, the mixed phosphor 1 has an emission spectrum located between the first phosphor 1 and the second phosphor 1, and the peak wavelength is shorter than the first phosphor 1 on the second wavelength side. It turns out that it exists in the long wavelength side rather than the fluorescent substance 1 of this.
Further, it can be seen from FIG. 8 that the emission spectrum of the mixed phosphor 1 has a broader waveform than the first phosphor 1 and the second phosphor 1.
Further, it can be seen from Table 2 that the emission chromaticity of the mixed phosphor 1 is longer than that of the second phosphor 2.

The chromaticity diagram of FIG. 9 shows the chromaticity coordinates Y1 to Y3 of the first phosphors 1 to 3 and the chromaticity coordinates Y4 to Y5 of the reference phosphors 1 to 2.
From the chromaticity diagram of FIG. 9, it can be seen that Y1 to Y5 are located substantially side by side on the dotted line D, which is a virtual straight line.
From this, the chromaticity coordinates of the phosphor represented by the general formula Sr _1-xy Ba _x Si ₂ O ₂ N ₂ : Eu ²⁺ _y are the values of x and y in the general formula on the dotted line D. The color of the phosphor that is located at any point according to the formula, the value of x in the general formula is 0.425 ≦ x ≦ 0.75, and x + y is in the range of 0.575 ≦ x + y ≦ 0.95 The chromaticity coordinates of the phosphor is located on the Y1 side of Y3, and the value of x in the general formula is in the range of 0 ≦ x <0.425 and x + y is in the range of 0.07 ≦ x + y <0.575. Is expected to be located on the Y5 side of Y2.

The chromaticity diagram of FIG. 10 shows chromaticity coordinates Y1 of the first phosphor 1, chromaticity coordinates Y6 to 7 of the second phosphors 1 and 2, and chromaticity coordinates Y8 of the mixed phosphor.

From the chromaticity diagram of FIG. 10 and Table 1, the chromaticity coordinate Y8 of the mixed phosphor 1 is more than the chromaticity coordinate Y6 of the second phosphor 1 alone due to the influence of the mixed first phosphor 1. Shifting to the long wavelength side, the mixed phosphor 1 has a dominant wavelength longer than that of the second phosphor 1 alone.
From this, the 1st fluorescent substance 1-3 which has shown the dominant wavelength longer wave than the 2nd fluorescent substance 1 is mixed with the 2nd fluorescent substance 1, and 2nd fluorescent substance 1 It is expected that a composite spectrum having a dominant wavelength longer than that of the single wave can be obtained.

<Examination of white light by additive color mixing>
As described above, the chromaticity range that can be reproduced by additive mixing of a semiconductor light emitting device having a peak wavelength of emission spectrum of 450 nm and each phosphor is the chromaticity range of the semiconductor light emitting device in the chromaticity diagrams of FIGS. 9 and 10. It can be represented approximately by straight lines L1 to L8 connecting the coordinate point B and the chromaticity coordinate points Y1 to Y8 of each phosphor.
From the chromaticity diagrams of FIGS. 9 and 10, the straight lines L4 to 5 (reference phosphors 1 to 2) indicate the range of the area A indicating the range of the chromaticity regulation (JIS D5500) of the white light source of the vehicle headlamp. Therefore, when these reference phosphors 1 and 2 are combined with a blue light emitting semiconductor light emitting element alone, it is expected that white light emission satisfying the chromaticity rule is impossible.

On the other hand, the straight lines L1 to 3 (first phosphors 1 to 3), L6 to 7 (second phosphors 1 to 2), and L8 (mixed phosphor) other than the above all pass through the range of the region A. Therefore, it is expected that white light that satisfies the chromaticity specification can be emitted by combining these phosphors with a blue light emitting semiconductor light emitting element.

When these phosphors are compared with the points X1 to 3 and the points X6 to 8 which are the intersections with the yellow phosphor side boundary line in the region A, the second phosphor 1 (Gd-free phosphor) has the point X6. Is located farther from the yellow phosphor than the points of the other phosphors, the white light emitting device using this is expected to have lower visibility of white light obtained than the other phosphors.
The second phosphor 2 (Gd-containing phosphor) has a point X7 that is point X of the second phosphor 1.
Since it is located closer to the yellow phosphor than 6, white light with higher visibility than the second phosphor 1 may be obtained, but there is a problem that the temperature characteristics are low as described above.

For these phosphors, the mixed phosphor 1 in which the first phosphor 1 and the second phosphor 1 are mixed, the point X8 is X6 (second phosphor 1) or X7 (second phosphor). It is expected that the white light emitting device using this is located on the yellow phosphor side of 2), and can obtain white light having higher visibility than the second phosphors 1 and 2.
Furthermore, as will be described later, since the first phosphor has excellent temperature characteristics, the mixed phosphor 1 is difficult to view with the second phosphor 1 (Gd-free phosphor) alone. It is expected that a white light-emitting device can be obtained that can obtain white light with high sensitivity and that is excellent in temperature characteristics that are a problem of the second phosphor 2 (Gd-containing phosphor).

11 and 12 are graphs showing temperature characteristics of the respective phosphors under excitation with 450 nm, measured using the measurement apparatus 10 shown in FIG. 3 described above.
The vertical axis of the graphs in FIGS. 11 and 12 shows the integrated luminescence intensity under each temperature condition for each phosphor as a ratio with the integrated luminescence intensity at 30 ° C. as 100%. .

FIG. 11 is a graph comparing the temperature characteristics of the first phosphors 1 to 3 and the second phosphor 2 (Gd-containing phosphor). From this graph, the first phosphors 1 to 3 have a lower rate of decrease in the integrated emission intensity due to the increase in temperature conditions than the second phosphor 2 (Gd-containing phosphor), and have excellent temperature characteristics. I understand. In particular, under the condition of 200 ° C., the second phosphor 2 (Gd-containing phosphor) is reduced to about 50%, while the first phosphors 1 to 3 all maintain 75% or more. You can see that

FIG. 12 is a graph comparing temperature characteristics of the mixed phosphor 1 and the second phosphor 2 (Gd-containing phosphor). From this graph, it can be seen that the mixed phosphor 1 has a maintenance rate of 80% or more even under the condition of 200 ° C. and has temperature characteristics superior to those of the second phosphor 2.

Next, the structure of the light-emitting device of an Example is explained in full detail.
In addition, the structure of the following light-emitting device is a structure common to an Example and a comparative example except the kind of used fluorescent substance.

<Configuration of light emitting device>
The light emitting device of this example uses the following specific configuration in the above embodiment.
First, an aluminum nitride substrate was used as the substrate 21, and an electrode 22a (anode) and an electrode 22b (cathode) were formed using gold on the surface.
Further, a 1 mm square LED having a light emission peak at 455 nm (manufactured by Cree: C460-EZ1000) was used as the semiconductor light emitting element 23, and a silver paste (Able Stick Co., Ltd.) dropped using a dispenser on the electrode 22a (anode). The lower surface of the LED was bonded onto the product: 84-1LMISS4), and the silver paste was cured for 1 hour in a 175 ° C. environment.
Further, a Φ45 μm gold wire was used as the wire 25, and this gold wire was bonded to the upper electrode of the LED and the electrode 22b (cathode) by ultrasonic thermocompression bonding.
Further, a silicone resin (manufactured by Toray Dow Corning Silicone Co., Ltd .: JCR6126) is used as a binder member, and a 30 vol% phosphor paste in which various phosphors are mixed is prepared, and the phosphor paste is applied to the upper surface of the semiconductor light emitting device 23. did. The coating amount was applied while adjusting the film thickness so as to obtain a desired chromaticity.
The phosphor layer 26 was formed by fixing the applied phosphor paste by step curing for 40 minutes in an 80 ° C. environment and then for 60 minutes in a 150 ° C. environment.

The following examples and comparative examples were produced based on the configuration of the phosphor and the light emitting device.
<Example>
In this example, a phosphor paste was prepared using the phosphor mixture 1, and a light emitting device in which the coating amount was adjusted using the phosphor paste so as to fall within the range of region A in the chromaticity diagram of FIG. Was made.
<Comparative example>
In this comparative example, a phosphor paste was prepared using the second phosphor 2, and the coating amount was adjusted using the phosphor paste so as to fall within the region A in the chromaticity diagram of FIG. A light emitting device was manufactured.

<Evaluation of Examples>
Hereinafter, measurement results of various light emission characteristics performed for Examples and Comparative Examples are shown.
First, a current of 100 mA is applied to each light emitting device in an integrating sphere for 10 msec to emit light, and the light ratio, chromaticity coordinates (cx, cy), and color rendering (Ra ) Was measured. The results are shown in Table 3.
The luminous flux ratio is shown as a relative value when the luminous flux when a current of 100 mA is supplied to the light emitting device of the comparative example is 1.00.

From Table 3, it can be seen that the light intensity of the example is 20% larger than that of the comparative example, and that the color rendering properties are almost equal. In addition, the light emission chromaticity of the example is white that is closer to yellow, and it can be seen that good visibility is obtained.

Next, in order to evaluate the temperature characteristics of each light emitting device, as shown in FIG. 12, the light emitting devices 20 of the example and the comparative example are installed on an aluminum heat sink 27, and a drive current of 100 mA is applied to the light emitting device. Then, after leaving in a thermostatic chamber at each ambient temperature for 20 minutes, the emission intensity was measured with an instantaneous multi-photometry system (manufactured by Otsuka Electronics Co., Ltd .: MCPD-1000). The measurement results are shown below.

Table 4 shows the integrated light emission intensity measured under each ambient temperature divided into the total light emission wavelength region (380 to 780 nm) of the light emitting device and the light emission wavelength region (500 to 780 nm) of the phosphor. This is shown as a ratio with the integrated light emission intensity at 0 ° C. as 100%.

From Table 4, the example shows a higher maintenance ratio than the comparative example for all the emission wavelength range of the light emitting device and the emission wavelength range of the phosphor, and the example has good temperature characteristics. I understand.

FIG. 14 shows an emission spectrum (solid line) under a 0 ° C. condition and a light emission spectrum (dotted line) under an 80 ° C. condition at a driving current of 100 mA.

FIG. 15 shows an emission spectrum (solid line) under a 0 ° C. condition and a light emission spectrum (dotted line) under an 80 ° C. condition at a driving current of 100 mA.

14 and 15, it can be seen that the light emission intensity of each light-emitting device decreases with temperature rise, but the light-emitting device of the example maintains a higher light emission intensity than the light-emitting device of the comparative example.

As described above, the phosphor of the present invention has been described with reference to the examples. However, the present invention is not limited to these examples, and it is needless to say that various modifications, improvements, combinations, usage forms, and the like can be considered.

The white light emitting device of the present invention is a vehicular lamp using a white light source and having a white functional color, for example, a head lamp, a fog lamp, a cornering lamp, a license plate lamp, a backup lamp, a room lamp, etc. Can do.
Further, the white light emitting device of the present invention is a vehicular lamp that is a combination of a white light source and a color filter, and can be used for a functional color other than a white system, for example, a tail lamp, a stop lamp, a turn signal lamp, or the like. .

FIG. 4 is a chromaticity diagram showing chromaticity coordinates of a Gd-free phosphor and a Gd-containing phosphor, and a reproducible chromaticity range of a white light emitting device using these phosphors. It is drawing which shows the emission spectrum (solid line) of Gd non-containing fluorescent substance, and the emission spectrum (dotted line) of Gd containing fluorescent substance. It is the schematic which shows the apparatus which measures the temperature characteristic of fluorescent substance. It is drawing which shows the temperature characteristic of Gd containing fluorescent substance and Gd non-containing fluorescent substance. It is a schematic sectional drawing which shows embodiment of the light-emitting device of this invention. 1 is a drawing showing an excitation spectrum of a first phosphor 1. The emission spectrum of the first phosphor 1 (dotted line), the emission spectrum of the first phosphor 2 (solid line), the emission spectrum of the first phosphor 3 (dashed line), and the emission spectrum of the second phosphor 1 It is drawing which shows (two-dot chain line). It is drawing which shows the emission spectrum (dotted line) of the 1st fluorescent substance 1, the emission spectrum (one-dot chain line) of the 2nd fluorescent substance 1, and the emission spectrum (solid line) of the mixed fluorescent substance 1. FIG. It is a chromaticity diagram showing the chromaticity coordinates of each phosphor and the reproducible chromaticity range of a white light emitting device using these phosphors. It is a chromaticity diagram showing the chromaticity coordinates of each phosphor and the reproducible chromaticity range of a white light emitting device using these phosphors. It is drawing which shows the temperature characteristic of each fluorescent substance. 4 is a diagram illustrating temperature characteristics of the mixed phosphor 1 and the second phosphor 2. It is a schematic sectional drawing which shows the light-emitting device at the time of measuring a temperature characteristic. It is a figure which shows the emission spectrum of an Example. It is a figure which shows the emission spectrum of a comparative example.

Explanation of symbols

10: Measuring device 11: Aluminum substrate 11a: Opening 12: Thermocouple 13: Planar heater 14: Condensing lens 15: Quartz fiber 16a, 16b: Spectrometer 17: Receiving quartz fiber 18: Phosphor 20: White light emission Device 21: substrate 22a: electrode (anode)
22b: Electrode (cathode)
23: Semiconductor light emitting element 24: Mount member 25: Wire 26: Fluorescent layer 27: Heat sink

Claims (9)

A white light emitting device used for a vehicle lamp,
A semiconductor light emitting device having an emission spectrum peak in a wavelength region of 370 to 480 nm, and at least two or more kinds of phosphors that are excited by light emitted from the semiconductor light emitting device to emit visible light,
As the phosphor, the general formula Sr _1-xy Ba _x Si ₂ O ₂ N ₂ : Eu ²⁺ _y (where x is 0.25 <x <1.0, y is 0.03 <y <0. 3 x + y is in the range of 0.3 <x + y <1.0) and cerium-activated yttrium aluminum garnet (YAG) having an emission peak wavelength between 510-600 nm. And a second phosphor which is a system phosphor. The x in the general formula is in the range of 0.425 ≦ x ≦ 0.750, y is in the range of 0.150 ≦ y ≦ 0.200, and x + y is in the range of 0.575 ≦ x + y ≦ 0.950. The white light emitting device according to 1. The white light emitting device according to claim 2, wherein the second phosphor does not contain gadolinium. The dominant wavelength of the emission spectrum of the first phosphor is in a wavelength range of 570 to 590 nm, and the dominant wavelength of the emission spectrum of the second phosphor is in a wavelength range of 565 to 573 nm. The white light-emitting device in any one of 1-3. The peak wavelength of the emission spectrum of the first phosphor is in a wavelength range of 565 to 610 nm, and the peak wavelength of the emission spectrum of the second phosphor is in a wavelength range of 540 to 560 nm. 5. The white light emitting device according to any one of 4 above. The dominant wavelength of the synthetic spectrum of said 1st fluorescent substance and said 2nd fluorescent substance exists in the wavelength range of 570-585 nm, and a half value width is 80 nm or more, The any one of Claims 1-5 characterized by the above-mentioned. The white light emitting device described. The first phosphor and the second phosphor are europium-activated orthosilicates prepared by first firing a mixture of SrCO ₃ , BaCO ₃ , SiO ₂ and Eu ₂ O _{3 in} a reducing atmosphere. A white light-emitting device according to any one of claims 1 to 6, wherein the white light-emitting device is obtained by secondarily firing a mixture of the precursor, Si ₃ N ₄ and NH ₄ Cl in a reducing atmosphere as a precursor. . The white light-emitting device according to claim 1, wherein the semiconductor light-emitting element is an InGaN-based LED having a peak wavelength in a wavelength range of 430 nm to 470 nm. The vehicle lamp which used the white light-emitting device in any one of Claims 1-8 as a light source.

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