JP4604516B2 - LIGHT EMITTING DEVICE, LIGHTING DEVICE USING SAME, AND DISPLAY - Google Patents

Description

  The present invention relates to a light emitting device used for a lighting device, a display, or the like. Specifically, combining a first light emitter that emits light in the ultraviolet to visible light range with a power source and a second light emitter that absorbs the light emission and emits long-wavelength visible light. Thus, the present invention relates to a light emitting device capable of generating light stably and highly efficiently regardless of the use environment.

Currently, light-emitting diodes (hereinafter sometimes abbreviated as LEDs) and laser diodes (hereinafter sometimes abbreviated as LDs) have been developed from the blue to red visible region to those emitting purple and ultraviolet rays. Display devices that combine such multicolored LEDs are used as displays and traffic signals. Furthermore, a light-emitting device in which the light emission color of the LED or LD is color-converted with a phosphor has been proposed. For example, in JP-B-49-1221, phosphor laser beam emitting a radiation beam having a wavelength of _{300~530nm (Ln 3-x-y} Ce x Gd y M 5-z Ga z O 12 (Ln is Y, Lu, or La, M represents Al, Al—In, or Al—Sc, x is 0.001 to 0.15, y is 2.999 or less, and z is 3.0 or less)). A method of forming a display by emitting light is shown.

  Further, in recent years, light emission of white light emission constituted by combining a gallium nitride (GaN) LED or LD having high light emission efficiency, which has been attracting attention as a blue light emitting semiconductor light emitting element, and a phosphor as a wavelength conversion material. An apparatus has been proposed as a light emission source for an image display device or an illumination device. For example, in Japanese Patent Laid-Open No. 10-242513, a nitride semiconductor LED or LD chip is used, and cerium is attached to the phosphor as a phosphor. A light emitting device comprising a combination of active yttrium, aluminum and garnet is shown.

  However, for example, in the combination of a cerium-activated yttrium / aluminum / garnet phosphor and a blue LED or a blue laser as disclosed in JP-A-10-242513, yellow light generated from the phosphor and the blue light is used. The white color can be generated by the mixed color of light, but the light emission in the middle region (470 nm-540 nm) of the blue and yellow emission peak tops (near 450 nm and 550 nm) and the longer wavelength side region (580-700 nm) from the yellow peak. Since the intensity is small, sufficient color reproducibility cannot be obtained as a light source such as a backlight source, and improvements are demanded.

In order to improve color reproducibility, there has been proposed a light emitting device that excites blue, red, and green phosphors and uses them as white light emission with ultraviolet light emitting LEDs. When blue, green, and red phosphors are mixed to produce white light, the two peaks do not overlap as in the conventional blue / yellow mixed color system. As a result, the valley of the color becomes smaller and the color rendering is improved. However, in this blue / green / red mixed color system, there is a need for each phosphor to have a well-balanced and sufficient luminous efficiency and spectral characteristics to exhibit color reproduction (wide color reproduction range or high color rendering). Japanese Unexamined Patent Application Publication Nos. 2000-183408 and 2000-073052 describe alkaline earth metal aluminate phosphors activated with Eu and Mn as blue and green phosphors. However, 2 (Ba, Mg) O.5Al ₂ O ₃ : Eu _0.2 , Mn _0.4 and (Ba, Mg) O.8Al ₂ O ₃ : Eu _0.2 , Mn ₀ are disclosed specifically. _In the composition of _.4 , the emission intensity was still not sufficient. In JP-A-2002-171000, SrAl ₂ O ₄ : Eu phosphors are listed as usable phosphors, but details on the composition ratio and the production method are not shown.

Further, it is very difficult to produce LEDs and LDs with a stable emission wavelength, and the emission center wavelength is shifted by a change in temperature and current, and when it is large, a deviation of 5 nm or more may occur. In the conventional phosphor, the emission intensity is greatly influenced by the variation in the emission wavelength, and not only the brightness but also the white chromaticity and color temperature when mixed are greatly changed. Therefore, it is desired to develop a phosphor that has high luminance and does not significantly change the light emission characteristics with respect to changes in the wavelength of the LED or LD.
Japanese Patent Publication No.49-1221 Japanese Patent Laid-Open No. 10-242513 JP 2000-183408 A JP 2000-073052 A JP 2002-171000 A

  As described above, when combining a conventional LED that emits ultraviolet light and mixing blue, green, and red phosphors to produce white light, a sufficient emission intensity for each phosphor and the mixture is combined as a whole. It is required to have chromaticity and spectral characteristics for exhibiting high color reproducibility, and it is also desired that the light emission output and chromaticity do not change due to variations in the light emission wavelengths of LEDs and LDs. The present invention has been made in view of the prior art, and an object of the present invention is to provide a light-emitting device that has a high emission intensity, is stable, and is easy to manufacture by developing a highly efficient green phosphor.

In the light emitting device having the first light emitter that generates light having a wavelength of 350 to 415 nm and the second light emitter that generates visible light by irradiation of light from the first light emitter. As the phosphor contained in the second phosphor, the above object is achieved by using an oxide phosphor having a specific emission characteristic, particularly a phosphor containing a crystal phase having a specific chemical composition. The present invention has been found out that it can be achieved.
That is, the present invention relates to a light emitting device having a first light emitter that generates light having a wavelength of 350 to 415 nm and a second light emitter that generates visible light by irradiation with light from the first light emitter. The second light emitter has a dominant wavelength between 488 nm and 570 nm, contains a crystal phase having the chemical composition of the following general formula [1], and only α-Al ₂ O ₃ is used as the Al source compound And the phosphor has an emission intensity when excited by light having a wavelength of 410 nm of 93% or more and 110% or less of an emission intensity when excited by light having a wavelength of 385 nm. The gist of the light emitting device is as follows.
[Chemical 1]
_{Sr a Eu b Mn c M d} A 2 O 4 [1]
(In the formula [1], a, b, c, d are 0.2 ≦ a ≦ 0.995, 0.005 ≦ b ≦ 0.8, 0 ≦ c ≦ 0.5, c ≦ b, a + b + c + d, respectively. = 1, A is selected from the group of Al, Ga, Sc, and B, and 50 mol% or more of A is Al, and M is a divalent metal element other than Sr, Eu, and Mn Is shown.)

  According to the present invention, it is possible to provide a light emitting device having high and stable emission intensity, and the light emitting device can be applied to various lighting devices and displays.

Hereinafter, the present invention will be described in detail.
The light-emitting device of the present invention includes a first light-emitting body that generates light having a wavelength of 350 to 415 nm and a second light-emitting body that generates visible light when irradiated with light from the first light-emitting body. The second light emitter in the device preferably has a high light emission intensity at the wavelength of the light emitted from the first light emitter, and the change in the light emission intensity is preferably small in all wavelength regions. It is preferable that the light emitting device has a small emission intensity change between 385 and 410 nm. For that purpose, the phosphors constituting the second light emitters, when blue, green, and red phosphors are combined and used as white light, each change even if the emission intensity change of each of the phosphors combined is somewhat large Except for special combinations where the rates are not different from each other, it is usually desirable that the emission intensity of each phosphor is high and the change is small.

  In general, when the wavelength of the light emitted from the first light emitter to the second light emitter is closer to the short wavelength side of the wavelength region (385 to 410 nm), the phosphor of the second light emitter has higher emission intensity. , Lower on the long wavelength side. In order to maintain a high efficiency with a small change in emission intensity over the entire wavelength range, the oxide phosphor of the second emitter in the light emitting device of the present invention has an emission intensity at the time of excitation with light having a wavelength of 410 nm. Is 93% or more, more preferably 95% or more of the emission intensity upon excitation with light having a wavelength of 385 nm. On the other hand, it is not preferable that the emission intensity at the excitation wavelength of 410 nm exceeds the emission intensity at the wavelength of 385 nm, and the emission intensity at the excitation by the light of wavelength 410 nm is 110% of the emission intensity at the excitation by the light of wavelength 385 nm. Or less, more preferably 105% or less.

  Furthermore, in the wavelength region (wavelength 350 to 415 nm) of the irradiation light from the first light emitter, the oxide phosphor of the second light emitter is less It is desirable that the absolute value of the emission intensity change rate in the excitation light having a predetermined wavelength is not more than a specific value. That is, the absolute value of the emission intensity change rate per unit wavelength in the wavelength region (wavelength 350 to 415 nm) of the irradiation light from the first light emitter is 1.5% or less, usually 385 nm or more and less than 390 nm, and 390 nm or more and less than 395 nm. 2.0% or less, 395 nm or more and less than 400 nm, 2.5% or less, and 400 nm or more and less than 410 nm, 3.0% or less. When the rate of change is larger than this value, the emission intensity from the second light emitter greatly increases or decreases when the emission peak wavelength of the first light emitter shifts to the short wavelength side or the long wavelength side from the normal value. To do.

  Furthermore, in the case of a light-emitting device that combines blue, green, and red phosphors, white color shift also occurs due to the difference in the emission intensity change rate of each phosphor. Therefore, it is difficult to manage the characteristics, and the emission intensity and chromaticity are unstable. Since it becomes a light-emitting device, it is not preferable practically. If the absolute value of the emission intensity change rate in each wavelength region is equal to or smaller than this value, the second emission peak wavelength of the first luminous body is also changed to the short wavelength side or the long wavelength side from the standard value. Variations in emission intensity from the illuminant are within an acceptable range, and a preferable light emitting device with stable emission intensity and chromaticity can be obtained. This value is more preferably 385 nm or more and less than 390 nm, 1% or less, 390 nm or more and less than 395 nm, 1.5% or less, 395 nm or more and less than 400 nm, 2% or less, 400 nm or more and less than 410 nm, 2.5% or less, Preferably, they are 385 nm or more and less than 390 nm and 0.5% or less, 390 nm or more and less than 395 nm, 0.8% or less, 395 nm or more and less than 400 nm, 1.2% or less, and 400 nm or more and less than 410 nm, and 2% or less.

  From such a viewpoint, the oxide phosphor of the second phosphor of the present invention has, as a specific index, the absolute value of the rate of change in emission intensity per unit wavelength at the wavelength of the irradiation light from the first phosphor. The ratio of the difference in emission intensity at both excitation wavelengths of the excitation wavelength ± 1 nm to the emission intensity at the excitation wavelengths of the predetermined wavelengths of 385 nm, 390 nm, 395 nm and 410 nm is 1.5% or less and 2.0% or less, respectively. , 2.5% or less, and 3.0% or less.

  Here, the absolute value of the emission intensity change rate is the difference in emission intensity between the predetermined excitation wavelength and ± 1 nm before and after the excitation wavelength by measuring the emission intensity at each excitation wavelength within ± 1 nm before and after the predetermined excitation wavelength. Is an absolute value of a value obtained by dividing the average of the absolute values by the emission intensity at a predetermined excitation wavelength, and is represented by the following equation.

但し、式中各変数は、以下の意味を表す。
ａ：変化率
λ：所定の励起波長
Ｉ(λ)：所定の励起波長λでの発光強度
Ｉ(λ−１)：励起波長(λ−１)ｎｍでの発光強度
Ｉ(λ＋１)：励起波長(λ＋１)ｎｍでの発光強度
なお、励起波長が変化しても、発光のスペクトル波形が変化しないことから、発光強度の変化率は、実質的に輝度変化率と等しい。

However, each variable in the formula represents the following meaning.
a: Rate of change
λ: predetermined excitation wavelength I (λ): emission intensity at predetermined excitation wavelength λ I (λ-1): emission intensity at excitation wavelength (λ-1) nm I (λ + 1): excitation wavelength (λ + 1) nm In addition, since the spectrum waveform of light emission does not change even if the excitation wavelength changes, the change rate of the light emission intensity is substantially equal to the luminance change rate.

  The phosphor contained in the second light emitter needs to be an oxide. For compounds other than oxides, such as sulfides, the rate of change in emission intensity is small, but when intense light having a wavelength of 350 to 415 nm generated from the first illuminant is irradiated, the emission intensity tends to decrease and is long. Use of period is difficult.

  The phosphor contained in the second light emitter is an oxide phosphor having a dominant wavelength usually between 488 nm and 570 nm. Further, the phosphor has a high emission intensity when the maximum emission intensity (emission peak) is observed within a wavelength range of 490 to 550 nm in an emission spectrum upon excitation with light having an excitation wavelength of 400 nm. It is preferable for obtaining a light emitting device close to natural light with a wide color reproduction range. Even if the wavelength of the emission peak is shorter than 490 nm or the wavelength is longer than 550 nm, the green color purity is deteriorated, and the luminance is lowered when white light described later is obtained.

  As the oxide phosphor contained in the second illuminant, the one containing a crystal phase having a chemical composition represented by the following general formula [1] is from the first illuminant that generates light having a wavelength of 350 to 415 nm. This is preferable because a light emitting device which is excited by the light of the above and exhibits high and stable light emission intensity and chromaticity and suitable for practical use can be obtained.

[Chemical 2]
_{Sr a Eu b Mn c M d} A 2 O 4 [1]
(In the formula [1], a, b, c, d are 0.2 ≦ a ≦ 0.995, 0.005 ≦ b ≦ 0.8, 0 ≦ c ≦ 0.5, c ≦ b, a + b + c + d, respectively. = 1, A is selected from the group of Al, Ga, Sc and B, and 50 mol% or more of A is Al, and M is a divalent metal element other than Sr, Eu and Mn Is shown.)
In either case where a is too small or too large, the emission intensity tends to decrease. A crystal phase having a chemical composition with a number satisfying 0.2 ≦ a ≦ 0.995 has high emission intensity and is stable.

  A crystal phase having a chemical composition in which b satisfies 0.005 ≦ b ≦ 0.8 has high emission intensity and is stable and preferable. When b is smaller than 0.005, the number of luminescent center ions is too small and sufficient luminescence intensity tends not to be obtained. On the other hand, when b is larger than 0.8, strong concentration quenching is observed, and the emission intensity tends to be low. For the same reason, the lower limit is preferably b ≧ 0.02, more preferably b ≧ 0.04, further preferably b ≧ 0.08, and most preferably b ≧ 0.15. Moreover, as an upper limit, b <= 0.7 is preferable, b <= 0.65 is more preferable, b <= 0.6 is still more preferable, b <= 0.55 is the most preferable.

  A crystal phase having a chemical composition where c satisfies 0 ≦ c ≦ 0.5 has high emission intensity and becomes stable. When c is too large, concentration quenching is observed in the green emission of Mn, and the emission intensity tends to be low. Although a composition with c = 0, that is, a composition that does not contain Mn, relatively good green light emission can be obtained, but a proper amount of Mn is present together with Eu in the crystal, and energy transfer from Eu to Mn Since strong green light emission is obtained and the stability increases against changes in excitation wavelength, the lower limit is preferably c ≧ 0.01, more preferably c ≧ 0.02, further preferably c ≧ 0.03, c ≧ 0.05 is most preferred. Moreover, as an upper limit, c <= 0.4 is preferable and c <= 0.3 is more preferable.

  The element represented by A in the general formula [1] of the crystal phase of the oxide phosphor contained in the second luminous body is usually at least one selected from the group consisting of Al, Ga, Sc, and B. Elements can be used. Further, it is preferable that the second luminous body contains a crystal phase having a chemical composition in which 50 mol% or more of A is Al. Further, it is more preferable that all of A is Al since not only the light emission characteristics are improved, but also the phosphor can be produced at low cost because the price of the raw material is low.

  As the element represented by M in the general formula [1] of the crystal phase of the phosphor contained in the second luminous body, a divalent metal element other than Sr, Eu, and Mn can be usually used. Examples of the metal element include, but are not limited to, Ca, Mg, Zn, Ba and the like. These metal elements can be used in a range that does not impair the performance of the phosphor, and can be used in a range that satisfies a + b + c + d = 1 in the formula.

  In the method for preparing the oxide phosphor included in the second phosphor of the present invention, first, the element in formula [1], that is, a divalent metal element represented by Sr, Eu, Mn, M, and A The compounds of metal elements such as Al, Ga, Sc, and B represented by the above are sufficiently mixed by various mixers that are employed as necessary. The mixing method is not limited to a dry method, and wet mixing in a liquid medium such as water or alcohol is possible, and a pulverization step may be added before or after the mixing. In the drying process in the case of wet mixing, various dispersion processors can be used in combination, or the prepared solution or slurry can be dried by spray drying or the like. Next, the mixture obtained by any method can be produced by heat treatment and baking.

  Among these pulverization and mixing methods, it is preferable to use a liquid medium because it is necessary to uniformly mix and disperse a small amount of compound throughout the element source compound of the luminescent center ion, and other elements. Also for the source compound, the wet method is preferable from the viewpoint of obtaining uniform mixing throughout. As a heat treatment method, in a heat-resistant container such as a crucible or a tray made of alumina or quartz, a temperature of 1300 ° C. or higher, more preferably 1330 ° C. to 1600 ° C., particularly preferably 1350 to 1500 ° C., in a specific atmosphere. Heat and bake for 10 minutes to 24 hours.

As the heating atmosphere, an atmosphere necessary for obtaining an ion state (valence) in which the element of the emission center ion contributes to light emission is selected. In the case of divalent Eu, Mn, or the like in the phosphor of the present invention, carbon monoxide, hydrogen, nitrogen, hydrogen, argon or the like alone or a mixture thereof is most preferable in a reducing atmosphere.
The flux used at the time of firing is preferably a boron-based material such as H ₃ BO ₃ or B ₂ O ₃ , and after the heat treatment, classification treatment or the like is performed as necessary.

  As raw material compounds that are element source compounds of each element such as Sr, Ca, Mg, Zn, Ba, Eu, Mn, and Al, oxides, hydroxides, carbonates, nitrates, sulfates of the respective elements, Examples thereof include oxalates, carboxylates, halides, and the like. These are selected in consideration of reactivity to the composite oxide and non-generation of NOx, SOx, etc. during firing.

If the raw material compounds of Sr and Ca are specifically exemplified, as the Sr source compound, SrO, Sr (OH) ₂ .8H ₂ O, SrCO ₃ , Sr (NO ₃ ) ₂ , SrSO ₄ , Sr (OCO) ₂ · H ₂ O, Sr (OCOCH ₃ ) ₂ · 0.5H ₂ O, SrCl _{2 and the} like can be mentioned, among which SrCO ₃ is preferable. As Ca source compounds, CaO, Ca (OH) ₂ , CaCO ₃ , Ca (NO ₃ ) ₂ .4H ₂ O, CaSO ₄ .2H ₂ O, Ca (OCO) ₂ .H ₂ O, Ca (OCOCH) ₃ ) ₂ · H ₂ O, CaCl _{2 and the} like are mentioned, and among them, CaCO ₃ is preferable.

If specifically exemplified for Mg and Zn, as a Mg source _{compound, MgO, Mg (OH) 2} , MgCO 3, Mg (OH) 2 · 3MgCO 3 · 3H 2 O, Mg (NO 3) 2 · 6H 2 O, MgSO ₄ , Mg (OCO) ₂ .2H ₂ O, Mg (OCOCH ₃ ) ₂ .4H ₂ O, MgCl _{2 and the} like, and as the Zn source compound, ZnO, Zn (OH) ₂ , ZnCO ₃ , Zn (NO ₃ ) ₂ , Zn (OCO) ₂ , Zn (OCOCH ₃ ) ₂ , ZnCl _{2 and the} like can be mentioned. MgCO ₃ Of these, ZnCO ₃ is preferred.

For Eu and Mn, which are the elements of the luminescent center ion, specific examples of the element source compound include Eu ₂ O ₃ , Eu ₂ (SO ₄ ) ₃ , Eu ₂ (OCO) ₆ , EuCl _2, EuCl _3, and the like. As the Mn source compound, MnCO ₃ .nH ₂ O, MnCl ₂ , Mn (NO ₃ ) ₂ .6H ₂ O, MnSO ₄ .nH ₂ O, MnBr ₂ , MnO, and MnO ₂ can be used.

The Al source compound, _alpha-Al 2 _{O 3} is used, in particular median particle size 0.1 to 1.0 [mu] m, the _alpha-Al 2 _{O 3} having the characteristics of specific surface area 1.5~15m ² / g and preferably More preferably, α-Al ₂ O ₃ having a center particle size of 0.3 to 0.7 μm and a specific surface area of 4.5 to 10 m ² / g is used. Other γ-Al ₂ O ₃ , Al (OH) ₃ , AlOOH, Al (NO ₃ ) ₃ · 9H ₂ O, Al ₂ (SO ₄ ) ₃ , Al ₂ (CO ₃ ) ₃ · nAl as Al source compounds (OH) ₃ , Al (CH ₃ COO) ₂ (OH), Al ₂ (C ₂ O ₄ ) ₃ · 4H ₂ O, etc. are also pretreated, and the like is passed to α-Al ₂ O ₃ having the above characteristics. Can be used.

The first illuminant in the present invention is an illuminant that generates light for irradiating the oxide phosphor, and generates light having a wavelength of 350 to 415 nm, but light having a peak wavelength in the range of 350 to 415 nm. A light-emitting body that generates is preferably used.
Specific examples of the first light emitter include a light emitting diode (LED) and a laser diode (LD). A laser diode is more preferable in terms of low power consumption. Of these, GaN LEDs and LDs using GaN compound semiconductors are preferred. This is because GaN-based LEDs and LDs have significantly higher light emission output and external quantum efficiency than SiC-based LEDs that emit light in this region, and are extremely bright with very low power when combined with the phosphor. This is because light emission can be obtained. For example, for a current load of 20 mA, the GaN system usually has a light emission intensity 100 times or more that of the SiC system.

  A GaN-based LED or LD preferably has an Al x Gay N light emitting layer, a GaN light emitting layer, or an In x Gay N light emitting layer. Among these, GaN-based LEDs having an InxGayN light-emitting layer are particularly preferable because the light emission intensity is very strong. In GaN-based LDs, those having a multiple quantum well structure of an InxGayN layer and a GaN layer are preferable. Is particularly preferred since it is very strong. In the above, the value of x + y is usually in the range of 0.8 to 1.2. In the GaN-based LED, those in which the light emitting layer is doped with Zn or Si or those without a dopant are preferable for adjusting the light emission characteristics.

  A GaN-based LED has these light emitting layer, p layer, n layer, electrode, and substrate as basic components, and the light emitting layer is sandwiched between n-type and p-type AlxGayN layers, GaN layers, or InxGayN layers. Those having a heterostructure are preferably high in luminous efficiency, and those having a heterostructure in a quantum well structure are further preferable because of higher luminous efficiency.

  In the present invention, it is particularly preferable to use a surface-emitting type light emitter, particularly a surface-emitting GaN-based laser diode (LD), as the first light-emitting body, because it increases the light emission efficiency of the entire light-emitting device. . A surface-emitting type illuminant is an illuminant that emits strong light in the surface direction of the film. In a surface-emitting GaN-based LD, the crystal growth of the light-emitting layer and the like is controlled, and the reflection layer and the like are well devised. By doing so, the light emission in the surface direction can be made stronger than the edge direction of the light emitting layer. When the surface emitting type is used, the light emission cross-sectional area per unit light emission amount can be increased compared to the type that emits light from the edge of the light emitting layer. As a result, the phosphor of the second light emitter is irradiated with the light. Since the irradiation area can be made very large with the same amount of light and the irradiation efficiency can be improved, stronger light emission can be obtained from the phosphor included in the second light emitter.

The second phosphor emits white light by combining an oxide phosphor containing the crystal phase having the chemical composition of the general formula [1] with another phosphor different from the oxide phosphor. Obtainable. That is, white light can be obtained as the second light emitter by combining the green phosphor constituting the oxide phosphor of the present invention with various blue phosphors and red phosphors.
Although there is no restriction | limiting in particular as another fluorescent substance which can be combined with the green fluorescent substance used for the light-emitting device of this invention, The following blue fluorescent substance and red fluorescent substance are preferable.

Examples of blue phosphors include (Ba, Sr) MgAl ₁₀ O ₁₇ : Eu, (Sr, Ca, Mg, Ba) ₁₀ (PO ₄ ) _{6 Cl 2} : Eu, Ba ₃ Mg ₂ SiO ₈ : Eu, Sr A phosphor such as ₂ P ₂ O ₇ : Eu can be used.
Among them, it is more preferable to combine with at least one of the four types of blue phosphors listed in the following (1) to (4).
(1) BaMgAl ₁₀ O ₁₇ : Eu-based blue phosphor A phosphor containing a crystal phase having a chemical composition represented by the following general formula [2] is preferable.

（式［２］において、Ｍ^１は、Ｂａ、Ｓｒ、およびＣａからなる群から選ばれた少なくとも一種の元素を表し、Ｍ^１’は、１価、又は、六配位時２価の状態で半径が０．９２Å以上の２価の金属元素（但し、Ｂａ、Ｓｒ、Ｃａ、Ｅｕは除く）からなる。

(In Formula [2], M ¹ represents at least one element selected from the group consisting of Ba, Sr, and Ca, and M ^{1 ′} represents a monovalent or divalent state in a hexacoordinate state. It consists of a divalent metal element (excluding Ba, Sr, Ca, Eu) having a radius of 0.92 mm or more.

M ² is at least one element selected from the group consisting of Mg and Zn, and M ^{2 ′} is a divalent metal element having a radius of less than 0.92Å in a divalent state in hexacoordination (provided that Mg and Zn are excluded).
M ³ is at least one element selected from the group consisting of Al, Ga, and Sc, and M ^{3 ′} represents a trivalent metal element (except for Al, Ga, and Sc).
a ¹ is 0.9 ≦ (a ¹ + b ¹ ) ≦ 1.1, b ¹ is 0.11 ≦ b ¹ ≦ 0.99, c ¹ is 0.9 ≦ c ¹ ≦ 1.1, and d ¹ is 9 ≦ ^{d 1} ≦ 11, ^{e 1} is number satisfying ^{15.3 ≦ e 1 ≦ 18.7,0 ≦ x} 1 <0.2,0 ≦ y 1 <0.2,0 ≦ z 1 <0.2 It is. )

（式［３］において、Ｍ^４はＥｕ及びＳｒ以外の金属元素を表す。また、ＸはＰＯ_４以外の１価のアニオン基を表す。ｃ^２及びｄ^２は、２．７≦ｃ^２≦３．３、０．９≦ｄ^２≦１．１を満足する数である。ａ^２及びｂ^２は、ともに０よりも大きくａ^２＋ｂ^２が５以下となる数であるが、ａ^２≧０．１又はｂ^２≧３という条件を満足する。） _{(2) Sr 10 (PO 4} ) 6 C l2: phosphor containing a crystal phase having a chemical composition of Eu-based blue phosphor represented by the following general formula [3] is preferable.

(In the formula [3], ^{M 4} represents a metal element other than Eu and Sr. Also, .c ² and ^{d 2} X represents a monovalent anionic group other than PO ₄ is, 2.7 ≦ ^{c 2} ≦ 3.3, 0.9 ≦ d ² ≦ 1.1 Numbers a ² and b ² are both greater than 0 and a ² + b ² is 5 or less, but a ² ≧ 0.1 or b ² ≧ 3 is satisfied.)

（式［４］において、Ｍ^１は、Ｂａ、Ｓｒ、およびＣａからなる群から選ばれる少なくとも一種の元素を合計で９０ｍｏｌ％以上含む金属元素を表し、Ｍ^２は、ＭｇおよびＺｎからなる群から選ばれる少なくとも一種の元素を合計で９０ｍｏｌ％以上含む金属元素を表し、Ｍ^３は、ＳｉおよびＧｅからなる群から選ばれる少なくとも一種の元素を合計で９０ｍｏｌ％以上含む金属元素を表し、ａ^３は２．７≦ａ^３≦３．３を満足する数、ｂ^３は０．０００１≦ｂ^３≦１．０を満足する数、ｃ^３は０．９≦ｃ^３≦１．１を満足する数、ｄ^３は１．８≦ｄ^３≦２．２を満足する数、ｅ^３は７．２≦ｅ^３≦８．８を満足する数である。） (3) Sr ₃ MgSi ₂ O ₈ : Eu-based blue phosphor A phosphor containing a crystal phase having a chemical composition represented by the following general formula [4] is preferable.

(In Formula [4], M ¹ represents a metal element containing 90 mol% or more in total of at least one element selected from the group consisting of Ba, Sr, and Ca, and M ² is selected from the group consisting of Mg and Zn. A metal element containing 90 mol% or more in total of at least one element selected, M ³ represents a metal element containing 90 mol% or more in total of at least one element selected from the group consisting of Si and Ge, a ³ Number satisfying 2.7 ≦ a ³ ≦ 3.3, b ³ satisfying 0.0001 ≦ b ³ ≦ 1.0, and c ³ satisfying 0.9 ≦ c ³ ≦ 1.1 D ³ is a number satisfying 1.8 ≦ d ³ ≦ 2.2, and e ³ is a number satisfying 7.2 ≦ e ³ ≦ 8.8.)

（式［５］において、Ｍ^５は、Ｃａを含有し、かつ、ＣａとＭｇからなる群から選ばれた少なくとも一種の元素が８０ｍｏｌ％以上を占める金属元素を表し、ＺはＰＯ_４ ^３−、ＢＯ_３ ^３−以外のアニオンを表す。ａ^４は０．００３≦ａ^４≦２．１、ｂ^４は２．７≦（ａ^４＋ｂ^４）≦３．３、ｃ^４は１．２≦ｃ^４≦２、ｄ^４は０≦ｄ^４≦０．１を満足する数である。） (4) (Ca, Mg) ₃ (PO ₄ ) ₂ : Eu blue phosphor A phosphor containing a crystal phase having a chemical composition represented by the following general formula [5] is preferable.

(In Formula [5], M ⁵ represents a metal element containing Ca and at least one element selected from the group consisting of Ca and Mg occupying 80 mol% or more, Z is PO ₄ ³⁻ , An anion other than BO ₃ ³⁻ is represented, a ⁴ is 0.003 ≦ a ⁴ ≦ 2.1, b ⁴ is 2.7 ≦ (a ⁴ + b ⁴ ) ≦ 3.3, and c ⁴ is 1.2 ≦ c. ⁴ ≦ 2, d ⁴ is a number satisfying 0 ≦ d ⁴ ≦ 0.1.)

As the red phosphor, phosphors such as Y ₂ O ₂ S: Eu, YAlO ₃ : Eu, YVO ₄ : Eu, Gd ₂ O ₂ S: Eu, and La ₂ O ₂ S: Eu are preferable.

  As a method of combining these phosphors, a method of laminating each phosphor in a film form, a method of mixing in a resin and laminating in a film form, a method of mixing in a powder form, and in a resin A method of dispersing, a method of laminating in a thin film crystal form, and the like can be used, but a method of mixing and using in the form of powder is preferable because white light can be obtained most easily and inexpensively.

  When a surface-emitting type is used as the first light emitter, the second light emitter is preferably a film. As a result, the cross-sectional area of the light from the surface-emitting light emitter is sufficiently large. Therefore, when the second light emitter is formed into a film in the direction of the cross section, the irradiation cross-section area of the phosphor from the first light emitter is irradiated. Becomes larger per unit amount of phosphor, so that the intensity of light emitted from the phosphor can be further increased.

  Further, when a surface-emitting type is used as the first light emitter and a film-like one is used as the second light emitter, the second light emitter directly in the form of a film on the light-emitting surface of the first light emitter. It is preferable to have a shape in which is contacted. Contact here means creating a state where the first light emitter and the second light emitter are in close contact with each other without a gap layer of air or gas between the surfaces in contact with each other. As a result, it is possible to avoid a light amount loss in which light from the first light emitter is reflected by the film surface of the second light emitter and oozes out, so that the light emission efficiency of the entire apparatus can be improved.

  FIG. 3 is a schematic perspective view showing the positional relationship between the first light emitter and the second light emitter in an example of the light emitting device of the present invention. In FIG. 3, 1 is a film-like second light emitter having the phosphor, 2 is a surface-emitting GaN-based LD as a first light emitter, and 3 is a substrate. In order to create a state in which they are in contact with each other, the LD 2 and the second light emitter 1 may be formed separately, and the surfaces may be brought into contact with each other by an adhesive or other means, or the light emitting surface of the LD 2 The second light emitter may be formed (molded) on top. As a result, the LD 2 and the second light emitter 1 can be brought into contact with each other.

  The light from the first illuminant and the light from the second illuminant are usually directed in all directions. However, when the phosphor powder of the second illuminant is dispersed in the resin, the light is out of the resin. A part of the light is reflected when exiting, so the direction of the light can be adjusted to some extent. Therefore, since light can be guided to an efficient direction to some extent, it is preferable to use a phosphor in which the phosphor powder is dispersed in a resin as the second luminous body. Further, when the phosphor is dispersed in the resin, the total irradiation area of the light from the first light emitter to the second light emitter is increased, so that the light emission intensity from the second light emitter can be increased. It also has the advantage of being able to.

  Examples of resins that can be used to disperse the second phosphor include epoxy resins, polyvinyl resins, polyethylene resins, polypropylene resins, polyester resins, acrylic resins, and the like. An epoxy resin is preferable from the viewpoint of good dispersibility. When the second phosphor powder is dispersed in the resin, the ratio of the second phosphor powder is usually 10 to 95% by weight, preferably 20 to 90% by weight based on the total weight of the phosphor powder and the resin. %, More preferably 30 to 80% by weight. If the phosphor powder is too much, the luminous efficiency may be reduced due to aggregation of the powder, and if it is too little, the luminous efficiency may be lowered due to light absorption and scattering by the resin.

  The light-emitting device of the present invention comprises a second light-emitting body containing the phosphor as a wavelength conversion material, and a light-emitting element (first light-emitting body) that generates light of 350 to 415 nm, The phosphor is a light emitting device capable of absorbing 350 to 415 nm light emitted from the light emitting element and generating high-intensity visible light regardless of the use environment. When white light is used, the color reproducibility is good. It is suitable for a light source such as a backlight light source, a light source such as a traffic light, an image display device such as a color liquid crystal display, and a lighting device such as a surface light source.

  The light emitting device of the present invention will be described with reference to the drawings. FIG. 4 is a schematic cross-sectional view showing an example of a light emitting device having a first light emitter (350 to 415 nm light emitter) and a second light emitter. Yes, 4 is a light emitting device, 5 is a mount lead, 6 is an inner lead, 7 is a first light emitter (350 to 415 nm light emitter), 8 is a phosphor-containing resin portion as a second light emitter, 9 is The conductive wire 10 is a mold member.

  As shown in FIG. 4, the light emitting device as an example of the present invention has a general bullet shape, and a first light emitter made of a GaN-based light emitting diode or the like is disposed in the upper cup of the mount lead 5. (350 to 415 nm phosphor) 7 is a phosphor-containing resin formed as a second phosphor by mixing and dispersing a phosphor in a binder such as an epoxy resin or an acrylic resin and pouring the mixture into a cup. It is fixed by being covered with the part 8. On the other hand, the first light emitter 7 and the mount lead 5, and the first light emitter 7 and the inner lead 6 are each electrically connected by a conductive wire 9, and these are entirely covered with a mold member 10 made of epoxy resin or the like, Protected.

Further, as shown in FIG. 5, the surface emitting illumination device 11 incorporating the light emitting device shown in FIG. 4 is formed on the bottom surface of a rectangular holding case 12 whose inner surface is light-impermeable such as a white smooth surface. A large number of light emitting devices 13 are arranged on the outer side by providing a power source and a circuit (not shown) for driving the light emitting device 13, and milky white acrylic is provided at a position corresponding to the lid portion of the holding case 12. A diffusion plate 14 such as a plate is fixed for uniform light emission.
Then, by driving the surface emitting illumination device 11 and applying a voltage to the first light emitter of the light emitting device 13, light of 350 to 415 nm is emitted, and a part of the light emission is used as the second light emitter. In the phosphor-containing resin part, the phosphor absorbs to emit visible light, and on the other hand, light emission with high color rendering properties is obtained by mixing with blue light or the like that is not absorbed by the phosphor. 14, is emitted upward in the drawing, and illumination light with uniform brightness is obtained within the surface of the diffusion plate 14 of the holding case 12.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

Example 1
SrCO ₃ ; 0.85 mol, α-Al ₂ O ₃ ; 1.0 mol, and Eu ₂ O ₃ ; 0.075 mol as an element source compound of the luminescent center ion were pulverized and mixed in a ball mill, and further pulverized H ₃ BO ₃ was mixed in an amount of 0.01 mol, and then passed through a nylon 100 mesh sieve to obtain a mixture. The obtained mixture was heated and fired at 1400 ° C. for 2 hours in a flow of nitrogen gas containing 4% hydrogen in an alumina crucible, and then subjected to classification treatment to obtain a green-emitting phosphor Sr _0.85 Eu _{0. .15} Al ₂ O ₄ was produced. The phosphor was excited at 400 nm, which is the dominant wavelength in the ultraviolet region of a GaN-based light emitting diode, and the emission spectrum was measured with an instantaneous multi-photometry system (MCPD-7000) manufactured by Otsuka Electronics Co., Ltd. FIG. 1 shows an emission spectrum of the phosphor obtained. The integrated intensity ratio in the 415 to 780 nm region of the emission spectrum at this time was 190% with respect to the phosphor sample (reference) of Comparative Example 1 described later. The emission spectrum peak value was 521 nm.

Next, excitation light having a half-value width of 10 nm from 350 nm to 415 nm is taken out with a spectroscope manufactured by JASCO Corporation (model number CT-10T) corrected for spectral intensity, and irradiated to the phosphor sample every 1 nm. The integrated intensity of the emission spectrum of 425 to 780 nm was measured, and the absolute value of the change rate of the emission intensity at each predetermined wavelength of 385, 390, 395, 400, and 410 nm was determined and shown in FIG. Table 1 below collectively shows the rate of change in emission intensity at each predetermined wavelength of 385, 390, 395, 400, and 410 nm. The emission intensity at 410 nm excitation was 97% of the emission intensity at 385 nm excitation.
As described above, the rate of change is the absolute value of the difference in emission intensity between the predetermined excitation wavelength and ± 1 nm before and after the predetermined excitation wavelength. This is a value represented by the absolute value of the value obtained by dividing the average value by the emission intensity at the predetermined excitation wavelength, and is represented by the above-described equation.

Comparative Example 1
The charged raw materials were BaCO ₃ ; 0.8 mol, MgCO ₃ ; 0.6 mol, γ-Al ₂ O ₃ ; 5 mol, and Eu ₂ O ₃ ; 0.1 mol, MnCO ₃ .0.5H ₂ O ( Ba _0.8 Mg _0.6 Eu _0.2 Mn _0.4 Al ₁₀ O _{17 The same} operation as in Example 1 was performed except that the heating conditions were 1400 ° C. A green phosphor having the following composition was obtained. The phosphor was excited at 400 nm, which is the dominant wavelength in the ultraviolet region of a GaN-based light emitting diode, and the emission spectrum intensity was measured in the same manner as in Example 1. The integrated intensity ratio at this time was set to 100% (reference). . The peak wavelength was 515 nm.
FIG. 2 shows the emission intensity change rate obtained by the same method as in Example 1. Table 1 below summarizes the rate of change at each predetermined wavelength of 385, 390, 395, 400, and 410 nm. The emission intensity at 410 nm excitation was 44% of the emission intensity at 385 nm excitation.

Example 2
SrCO ₃ ; 0.73 mol, α-Al ₂ O ₃ ; 1.0 mol, Eu ₂ O ₃ as an element source compound of the luminescent center ion; 0.125 mol, and MnCO ₃ .0.5H ₂ O (as Mn 0.02 mol) was heated at 1450 ° C. for 2 hours, and Sr _0.73 Eu _0.25 Mn _0.02 Al ₂ O ₄ was produced in the same manner as in Example 1. When the emission characteristics of the produced phosphor were evaluated in the same manner as in Example 1, the integrated intensity ratio in the 415 to 780 nm region of the emission spectrum was 181% with respect to the sample of Comparative Example 1.
Further, the rate of change in emission intensity at each excitation wavelength of 385, 390, 395, 400, and 410 nm was determined in the same manner as in Example 1, and the results are shown in Table 1 below. The emission intensity at 410 nm excitation was 98% of the emission intensity at 385 nm excitation.

Comparative Example 2
SrCO ₃ ; 0.73 mol, γ-Al ₂ O ₃ ; 1.0 mol, Eu ₂ O ₃ as an element source compound of the luminescent center ion; 0.125 mol, and MnCO ₃ .0.5H ₂ O (as Mn 0.02 mol) was heated at 1300 ° C. for 2 hours, and Sr _0.73 Eu _0.25 Mn _0.02 Al ₂ O ₄ was produced in the same manner as in Example 1. When the emission characteristics were evaluated in the same manner as in Example 1, the integrated intensity ratio in the 415 to 780 nm region of the emission spectrum was 124% with respect to the sample of Comparative Example 1.
Further, the rate of change in emission intensity at each excitation wavelength of 385, 390, 395, 400, and 410 nm was determined in the same manner as in Example 1, and the results are shown in Table 1 below. The emission intensity at 410 nm excitation was 90% of the emission intensity at 385 nm excitation.

Example 3
The charged raw materials were SrCO ₃ ; 0.7 mol, basic magnesium carbonate (0.05 mol of Mg), α-Al ₂ O ₃ ; 1 mol, Eu ₂ O ₃ ; 0.1 mol, and MnCO ₃ -Sr _0.45 Mg _0.05 Eu _{0. 0} as in Example 1 except that 0.5H ₂ O (as Mn, 0.1 mol) and heating / firing were changed at 1600 ° C for 2 hours _{. 4} Mn _0.1 Al ₂ O ₄ was produced. When the emission characteristics were measured in the same manner as in Example 1, the emission spectrum integrated intensity ratio with excitation at 400 nm was 130% with respect to the sample of Comparative Example 1.
Further, the rate of change in emission intensity at each excitation wavelength of 385, 390, 395, 400, and 410 nm was determined in the same manner as in Example 1, and the results are shown in Table 1 below. The emission intensity at 410 nm excitation was 97% of the emission intensity at 385 nm excitation.

Example 4
SrCO ₃ ; 0.7 mol, α-Al ₂ O ₃ ; 1.0 mol, Eu ₂ O ₃ as an element source compound of the luminescent center ion; 0.125 mol, and MnCO ₃ .0.5H ₂ O (as Mn 0.02 mol) was heated at 1330 ° C. for 2 hours, and Sr _0.73 Eu _0.25 Mn _0.02 Al ₂ O ₄ was produced in the same manner as in Example 1. When the emission characteristics were evaluated in the same manner as in Example 1, the integrated intensity ratio in the 415 to 780 nm region of the emission spectrum was 172% with respect to the sample of Comparative Example 1.
Further, the rate of change at each excitation wavelength of 385, 390, 395, 400, and 410 nm was determined in the same manner as in Example 1, and the results are shown in Table 1 below. The emission intensity at 410 nm excitation was 95% of the emission intensity at 385 nm excitation.

The emission spectrum of the phosphor obtained in Example 1. The rate of change in excitation wavelength and emission intensity of the phosphors obtained in Example 1 and Comparative Example 1. The figure which shows an example of the light-emitting device which made the surface-emitting type GaN-type diode contact or shape | mold the film-like 2nd light-emitting body. FIG. 3 is a schematic cross-sectional view illustrating an example of a light emitting device including a first light emitter (350 to 415 nm light emitter) and a second light emitter in the present invention. The typical sectional view showing an example of the surface emitting illumination device of the present invention.

Explanation of symbols

1; second light emitter 2; surface-emitting GaN-based LD
3; Substrate 4; Light emitting device 5; Mount lead 6; Inner lead 7; First light emitter (light emitter of 350 to 415 nm)
8; Resin part containing phosphor in the present invention 9; Conductive wire 10; Mold member 11; Surface-emitting illumination device 12 incorporating a light-emitting device 12; Holding case 13; Light-emitting device 14;

Claims (8)

In a light emitting device including a first light emitter that generates light having a wavelength of 350 to 415 nm and a second light emitter that generates visible light by irradiation of light from the first light emitter, the second light emitter However, an oxide phosphor having a dominant wavelength in the wavelength range of 488 nm to 570 nm, containing a crystal phase having a chemical composition of the following general formula [1], and using only α-Al ₂ O ₃ as an Al source compound And the phosphor has a light emission intensity when excited by light having a wavelength of 410 nm of 93% or more and 110% or less of a light emission intensity when excited by light having a wavelength of 385 nm.
[Chemical 1]
_{Sr a Eu b Mn c M d} A 2 O 4 [1]
(In the formula [1], a, b, c, d are 0.2 ≦ a ≦ 0.995, 0.005 ≦ b ≦ 0.8, 0 ≦ c ≦ 0.5, c ≦ b, a + b + c + d, respectively. = 1, A is selected from the group of Al, Ga, Sc, and B, and 50 mol% or more of A is Al, and M is a divalent metal element other than Sr, Eu, and Mn Is shown.)       The oxide phosphor of the second light emitter has an absolute value of a change rate of emission intensity per predetermined (unit) wavelength in the wavelength of light emitted from the first light emitter having a predetermined wavelength of 385 nm, 390 nm, 395 nm, and 410 nm. The ratio of the difference in emission intensity at both excitation wavelengths ± 1 nm to the emission intensity at the excitation wavelength is 1.5% or less, 2.0% or less, 2.5% or less, and 3.0, respectively. The light emitting device according to claim 1, wherein the light emitting device is at most%.       The second phosphor contains an oxide phosphor whose maximum emission intensity is observed within a wavelength range of 490 to 550 nm in an emission spectrum upon excitation with light having an excitation wavelength of 400 nm. Or the light-emitting device of 2. 4. The light-emitting device according to claim 1, wherein A in the formula [1] is Al. First light emitter emitting device according to any one of claims 1 to 4, characterized in that a laser diode or a light emitting diode. The second light emitter further comprises other blue and red phosphors other than the oxide phosphor having the chemical composition of the general formula [1], and the light emitting device emits white light. The light emitting device according to any one of claims 1 to 5 . The illuminating device provided with the light-emitting device of any one of Claims 1 thru | or 6 . Display with a light emitting device according to any one of claims 1 to 6.

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