JP2010059429A - Phosphor, luminescent device using the same, image display and illuminating device - Google Patents

Abstract

Provided is a phosphor with extremely high emission intensity and a light emitting device using the same.
An Ln source compound (Ln may contain 50 mol% or more of La and may contain at least one element selected from Sc, Y, La, Gd, Lu, Bi), an S source compound , A phosphor obtained by firing an Eu source compound in contact with three types of alkali metal sulfides of Li, Na, and K, and the maximum when irradiated with excitation light in the wavelength range of 300 to 450 nm the emission intensity I _max of the case where the emission intensity when irradiated with excitation light having a wavelength of 400nm was I _400, and the their emission intensity ratio I ₄₀₀ / I _max is 0.57 or more, _{(Ln 1-x} A phosphor having a crystal phase with a chemical composition of Eu _x ) ₂ O ₂ S (x is 0.07 ≦ x ≦ 0.35). A light emitting device having high emission intensity can be obtained by using a first light emitter that generates light of 350 to 415 nm as an excitation source and the phosphor as a second light emitter.
[Selection figure] None

Description

  The present invention relates to a phosphor, a light emitting device, an image display device, and an illumination device, and more specifically, a first light emitter that emits light from ultraviolet light to visible light region by a power source, and from the ultraviolet light to visible light region. By combining the second phosphor as a wavelength conversion material that absorbs certain light and emits long-wavelength visible light, and the host compound has a phosphor containing a luminescent center ion, color rendering can be achieved regardless of the use environment. The present invention relates to a light emitting device capable of generating good and high-intensity light emission, an image display device and an illumination device using the light emitting device, and a phosphor used in the light emitting device.

In order to generate white and other various colors uniformly and with good color rendering by mixing blue, red, and green, a light emitting device in which the light emission color of an LED or LD is converted with a phosphor has been proposed. For example, Patent Document 1, the phosphor of the beam of laser emitting a radiation beam having a wavelength of _{300~530nm (Y 3-xy Ce x} Gd y M 5-z Ga z O 12 (Y is Y, Lu or La, M Is Al,
Al-In or Al-Sc is represented. )), And a method of forming a display by emitting light is shown. Further, in recent years, a white light emitting device configured by combining a gallium nitride (GaN) LED or LD with high luminous efficiency, which has been attracting attention as a blue light emitting semiconductor light emitting element, and a phosphor as a wavelength conversion material. However, it has been proposed as a light-emitting source for an image display device and a lighting device, taking advantage of the feature of low power consumption and long life. In fact, Patent Document 2 discloses a light emitting device using the nitride semiconductor LED or LD chip and using an yttrium, aluminum, garnet phosphor as the phosphor. Patent Document 3 discloses a substance that combines a red phosphor, a green phosphor, and a blue phosphor as a substance capable of generating white light emission upon irradiation with light in a 360 nm to 380 nm region typified by light from an LED. are, as a red phosphor _{(La 1-xy Eu x Sm} y) 2 O 2 S (x = 0.01~0.15, y = 0.0001~0.03)
Has been raised.

However, so far, it is particularly red in a light emitting device in which an yttrium / aluminum / garnet phosphor as shown in Patent Document 2 is combined as a second light emitter with respect to a first light emitter such as an LED. Therefore, further improvement is demanded as a light source such as a display, a backlight light source, and a traffic light. Also described as a conversion material into red visible light LED light as described in Patent Document _{3 (La 1-xy Eu x} Sm y) 2 O 2 S for phosphor emission intensity is low, a higher There is a need for emission intensity.

Japanese Patent Publication No.49-1221 Japanese Patent Laid-Open No. 10-242513 JP-A-11-246857

  An object of the present invention is to provide a phosphor, a light emitting device, an image display device, and an illumination device that are easy to manufacture and have extremely high emission intensity in view of the above-described conventional technology.

  As a result of intensive studies to solve the above problems, the inventor of the present invention has a first light emitter that emits light of 350 to 415 nm and a second light that generates visible light by irradiation of light from the first light emitter. In the light-emitting device having the light-emitting body, the second light-emitting body contains the specific phosphor of the present invention, whereby a light-emitting device having a remarkably high emission intensity of the red component can be obtained. It has been found that when the emission wavelength of the first light emitter is 385 to 415 nm, a light emitting device having a remarkably high light emission intensity can be obtained by including the phosphor of the present invention as the second light emitter. Reached.

  Further, a phosphor containing a crystal phase having a chemical composition of the following general formula [1] is used, and among them, an appropriate ratio of Eu in the crystal phase having the chemical composition of the following general formula [1] is set appropriately. The inventors have found that the object can be achieved by adjusting the range to be used, and have reached the present invention.

(However, in the general formula [1], Ln represents at least one element selected from Sc, Y, La, Gd, Lu, and Bi, and x satisfies 0.07 ≦ x ≦ 0.35. Number.)
Therefore, the present invention has been made based on such knowledge, and the gist thereof is that the maximum emission intensity when irradiating excitation light within a wavelength range of 300 nm to 450 nm is I _max and the wavelength is 400.
When the emission intensity when irradiated with excitation light of nm is I ₄₀₀ , the Ln ₂ O ₂ S: Eu phosphor whose emission intensity ratio I ₄₀₀ / I _max is 0.4 or more (where Ln Represents at least one element selected from Sc, Y, La, Gd, Lu, and Bi.), A light-emitting device using the element, and an image display device or illumination device including the light-emitting device.

  According to the present invention, a phosphor with extremely high emission intensity can be provided, and by using the phosphor, a light-emitting device with high emission intensity that is useful for an image display device and an illumination device can be provided. .

It is a typical perspective view which shows an example of the light-emitting device which made the film-like fluorescent substance contact the surface emitting type GaN-type diode. It is typical sectional drawing which shows one Example of the light-emitting device of this invention. It is typical sectional drawing which shows an example of the surface emitting illumination device of this invention.

In the present invention, when the maximum emission intensity when irradiating excitation light within a wavelength range of 300 nm to 450 nm is I _max and the emission intensity when irradiating excitation light having a wavelength of 400 nm is I ₄₀₀ , the light emission Ln ₂ O ₂ S: Eu phosphor characterized in that the intensity ratio I ₄₀₀ / I _max is 0.4 or more (where Ln is at least selected from Sc, Y, La, Gd, Lu, Bi) And a light-emitting device, an image display device, and a lighting device using the same. A light-emitting device, an image display device, and a lighting device that have high emission characteristics only when a characteristic phosphor is used. It is an embodiment of the device.

In the phosphor of the present invention, the maximum emission intensity I _max when irradiated with excitation light in the wavelength range of 300 nm to 450 nm, and the emission intensity I ₄₀₀ when irradiated with excitation light having a wavelength of 400 nm are measured by a fluorescence spectrophotometer. Can be measured. Specifically, the emission intensity of the emission peak showing the maximum intensity within the wavelength range of 620 nm to 630 nm where the Ln ₂ O ₂ S: Eu phosphor emits light is observed, and the wavelength of the excitation light irradiated to this phosphor is determined. After obtaining an excitation spectrum by scanning within a wavelength range of 300 nm to 450 nm, the maximum emission intensity obtained from the excitation spectrum was I _max , and the emission intensity when the excitation wavelength was 400 nm was I ₄₀₀ . And the fluorescent substance of this invention can be specified by calculating _| requiring those luminescence intensity ratio _I400 / Imax.

In the phosphor of the present invention, the emission intensity ratio I ₄₀₀ / I _max is 0.4 or more. When the value of I ₄₀₀ / I _max is small, the light emission from the first light emitter that emits light of 350 to 415 nm is sufficiently absorbed and cannot be emitted. As a result, a light emitting device with low efficiency is obtained. In addition, the larger the emission intensity ratio, the more stable the emission intensity of the phosphor that is the second light emitter even when the wavelength of the first light emitter that exhibits the maximum light emission intensity near 400 nm occurs. This is preferable because it leads to stabilization of the light emission characteristics of the light-emitting device, that is, even if the wavelength of the excitation source varies somewhat, it is difficult to be affected by it. Therefore, the value of the emission intensity ratio I ₄₀₀ / I _max is preferably 0.5 or more, more preferably 0.55 or more, still more preferably 0.57 or more, and particularly preferably 0.65 or more. A light emitting device having higher light emission intensity and more stable light emission characteristics can be obtained as the value is larger. Note that the maximum value of the emission intensity ratio is 1, and at this time, a light emitting device having the highest emission intensity and stable emission characteristics can be obtained.

  In addition, the phosphor of the present invention preferably has a wavelength showing a maximum light emission intensity of 330 nm or more when irradiated with excitation light within a wavelength range of 300 nm to 450 nm, and such a phosphor is used for a light emitting device. As a result, a light emitting device exhibiting particularly high light emission intensity can be obtained. When the wavelength indicating the maximum emission intensity is less than 330 nm, it becomes difficult to absorb the light from the first light emitter, and thus the efficiency of the light emitting device using this phosphor tends to be low. Therefore, in order to effectively absorb the light from the first light emitter, the wavelength showing the maximum light emission intensity is preferably 360 nm or more, more preferably 370 nm or more, and more preferably 375 nm or more. Is particularly preferable, and it is most preferable to exceed 375 nm.

In the phosphor of the present invention, the product α _q · η _i of the quantum absorption efficiency α _q and the internal quantum efficiency η _i when irradiated with excitation light having a wavelength of 400 nm is preferably 0.15 or more. When the value of α _q · η _i is small, the light emitted from the phosphor, which is the second light emitter, is absorbed by absorbing the light from the first light emitter, and is obtained using this phosphor. The light emission intensity of the light emitting device is relatively low. Therefore, this product is more preferably 0.25 or more, and further preferably 0.3 or more. A larger value is preferable because the luminous efficiency of the phosphor is increased, and a light emitting device using the phosphor is also preferable because it is highly efficient. However, the upper limit of the product value is theoretically 1.

The quantum absorption efficiency α _q , the internal quantum efficiency η _i , and their product α _q · η _i can be easily obtained by the following method. That is, first, a powder sample or the like to be measured is packed in a cell with a sufficiently smooth surface so as to maintain measurement accuracy, and is attached to a spectrophotometer with an integrating sphere or the like. An example of this spectrophotometer is MCPD2000 manufactured by Otsuka Electronics Co., Ltd. An integrating sphere or the like is used so that all the photons reflected by the sample and the photons emitted from the sample by photoluminescence can be counted, that is, photons that are not counted and fly out of the measurement system are eliminated. A light source for exciting the phosphor is attached to the spectrophotometer. The light emission source is, for example, an Xe lamp or the like, and is adjusted using a spectroscope, a filter, or the like so that the emission peak wavelength is 400 nm. A sample to be measured is irradiated with light from a light source adjusted to have a wavelength peak of 400 nm, and the emission spectrum is measured. This measured spectrum actually includes the amount of excitation light reflected by the sample in addition to the photons emitted from the sample by photoluminescence with light from the excitation light source (hereinafter simply referred to as excitation light). Photon contributions overlap.

The absorption efficiency α _q is a value obtained by dividing the number of photons _Nabs of the excitation light absorbed by the sample by the total number of photons N of the excitation light. First, the total number of photons N of the latter excitation light is obtained as follows. That is, a substance having a reflectance of almost 100% with respect to the excitation light, for example, a Spectralon manufactured by Labsphere (having a reflectance of 98% with respect to the excitation light of 400 nm) is attached to the spectrophotometer as a measurement object, and light is emitted. The spectrum I _ref (λ) is measured. Here, the numerical value obtained from (Formula 1) from the emission spectrum I _ref (λ) is proportional to N.

Here, the integration interval may be substantially only the interval in which I _ref (λ) has a significant value. In order to obtain the absorptance at 400 nm, it is sufficient to take in the range of 380 nm to 420 nm.
The former _Nabs is proportional to the amount obtained by (Equation 2).

Here, I (λ) is an emission spectrum when a target sample for which α _q is to be obtained is attached. The integration range of (Expression 2) is the same as the integration range defined in (Expression 1). By limiting the integration range in this way, the second term in (Equation 2) corresponds to the number of photons generated by the target sample reflecting the excitation light, that is, out of all photons generated from the target sample. This corresponds to the one excluding the photons generated by the photoluminescence by the excitation light. Since an actual spectrum measurement value is generally obtained as digital data divided by a certain finite bandwidth with respect to λ, the integrals of (Equation 1) and (Equation 2) are obtained by the sum based on the bandwidth. From the above, α _q = N _abs / N = (Expression 2) / (Expression 1).

Next, a method for obtaining the internal quantum efficiency η _i will be described. η _i is a value obtained by dividing the number N _PL of photons generated by photoluminescence by the number _Nabs of photons absorbed by the sample.
Here, N _PL is proportional to the amount obtained by (Equation 3).

At this time, the integration interval is limited to the wavelength range of photons generated from the sample by photoluminescence. This is because the contribution of photons reflected from the sample is removed from I (λ). Specifically, the lower limit of the integration of (Expression 3) is the upper end of the integration of (Expression 1), and the upper limit is a range suitable for including a photoluminescence-derived spectrum. Specifically, 420 nm to 780 nm may be set in the integration range in (Expression 3). Thus, η _i = (Expression 3) / (Expression 2) is obtained. The actual data is obtained by the sum based on the bandwidth from the spectrum that has become digital data, as in the case of obtaining _αq .

  The phosphor of the present invention usually contains a crystal phase having a chemical composition represented by the following general formula [1].

  In the general formula [1], usually Ln represents at least one element selected from Sc, Y, La, Gd, Lu, and Bi. However, Ln is basically at least one element selected from the above element group, but trivalent elements other than Sc, Y, La, Gd, Lu, Bi, for example, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Sb, B, Al, Ga, In, Mn and the like can also be contained in a small amount. Further, a trace amount of divalent metal elements such as Mg, Ca, Sr, Ba, Zn, Cd, and Mn, and tetravalent metals such as Si, Ge, Sn, Pb, Ti, Zr, and Hf can be contained. By containing a small amount of these elements, the light emission characteristics can be finely adjusted.

Further, as the element of Ln, the light emission intensity ratio I ₄₀₀ / I _max tends to increase as the ion radius increases, and it is preferable that La is the main component of the Ln element. Therefore, La is preferably 50 mol% or more of Ln element, more preferably 80 mol% or more, and particularly preferably Ln element is La alone.
X indicating the concentration of Eu, which is a luminescent material, is usually a number that satisfies 0.07 ≦ x ≦ 0.35. When the Eu concentration is low, the absorption efficiency of the excitation light from the first light emitter by the phosphor tends to decrease and the light emission efficiency tends to be low. On the other hand, if the Eu concentration is too high, concentration quenching tends to occur, and thus the light emission efficiency tends to be low, and the decrease in light emission intensity (decrease in temperature characteristics) due to the increase in the use temperature of the light emitting device tends to become remarkable. It is not preferable. For this reason, the Eu concentration is preferably in the range of 0.07 ≦ x ≦ 0.25, more preferably in the range of 0.07 ≦ x ≦ 0.2, and 0.08 ≦ x ≦ 0.15 from the viewpoint of temperature characteristics. Is most preferable, and the range of 0.15 <x ≦ 0.2 is most preferable from the viewpoint of light emission intensity.

  The phosphor used in the present invention promotes the Ln source, the S source compound, the luminescent center ion (Eu) element source compound, and the solid phase reaction and crystal growth as shown in the general formula [1]. After pulverizing the raw material for the flux using a dry pulverizer such as a hammer mill, roll mill, ball mill, jet mill, etc., and mixing with a mixer such as a ribbon blender, V-type blender, Henschel mixer, etc. , A dry method of pulverizing using a dry pulverizer, or adding these compounds into a medium such as water and pulverizing and mixing them using a wet pulverizer such as a medium stirring pulverizer, or these compounds After being pulverized by a dry pulverizer, the prepared pulverized mixture is prepared by a wet method in which a slurry prepared by adding and mixing in a medium such as water is dried by spray drying or the like. It can be produced by calcining heat treatment to.

Among these pulverization and mixing methods, in particular, in the element source compound of the luminescent center ion, it is preferable to use a liquid medium because it is necessary to uniformly mix and disperse a small amount of the compound over the whole. The latter wet method is also preferred from the aspect of obtaining uniform mixing throughout the element source compound.
The heat treatment is performed in a heat-resistant container such as a crucible or tray made of alumina or quartz, but when an alkali metal-containing flux is used, a phosphor with good characteristics can be obtained. It is preferable to use an alumina crucible having low reactivity.

The firing temperature is usually 1150 to 1500 ° C., but preferably 1200 to 1400 ° C. If the temperature is too low, the solid phase reaction and crystal growth do not proceed sufficiently, and the luminescent properties deteriorate. On the other hand, if the temperature is too high, sulfur easily escapes from the phosphor, and the amount of oxygen contained in the synthesized phosphor increases and the light emission characteristics deteriorate.
As long as the phosphor firing atmosphere uses a good sealing property to prevent the sulfur component from being volatilized and the phosphor is not exposed to an oxidizing atmosphere, the atmosphere, oxygen, carbon monoxide, carbon dioxide, nitrogen, Although it can be fired in a gas atmosphere such as hydrogen, argon, hydrogen sulfide, sulfur dioxide or the like alone or in a mixed atmosphere, a non-oxidizing atmosphere is preferred when a crucible with low hermeticity is used or when a crucible is not used. In any case, firing in a neutral or reducing atmosphere in a single or mixed atmosphere of gases such as carbon monoxide, carbon dioxide, nitrogen, hydrogen, argon, hydrogen sulfide, sulfur monoxide, sulfur dioxide, and sulfur. A sulfur-containing atmosphere is particularly preferable from the viewpoint of obtaining a phosphor having good characteristics, and a nitrogen atmosphere is particularly preferable from the viewpoint that the phosphor can be fired at low cost. If the phosphor is directly exposed to an oxidizing atmosphere at a high temperature, desired fluorescence characteristics cannot be obtained.

The firing holding time at the desired temperature is selected within the range of 1 minute to 24 hours, and preferably 30 minutes to 8 hours. If the firing holding time is too short, solid phase reaction and crystal growth will not proceed. On the other hand, if the firing holding time is too long, the volatilization of sulfur from the phosphor becomes noticeable and the light emission characteristics deteriorate, and wasteful energy is consumed to increase the manufacturing cost of the phosphor.
In addition, after heat processing, washing | cleaning, drying, a classification process, etc. are made | formed as needed. In particular, it is preferable to wash the phosphor using water since unnecessary flux components can be removed at low cost and the light emission characteristics can be improved. In addition, the emission characteristics can be further improved by washing with water containing hydrochloric acid.

Examples of Ln source and Eu source compounds include Ln and Eu oxides, hydroxides, carbonates, nitrates, sulfates, oxalates, carboxylates, halides, etc. , Sulfur powder, alkali sulfide, thiourea, thioacetamide, hydrogen sulfide gas, alkali sulfide, and the like. These are selected in consideration of chemical composition and reactivity.
In order to obtain the phosphor of the present invention, it is important to select an appropriate firing temperature, time, and atmosphere. However, the proper selection of the flux promotes the solid-phase reaction and the crystal growth, so that the phosphor can be excited. Is very important because the wavelength can be increased. In order to obtain the phosphor of the present invention, it is important to bring the phosphor into contact with a flux having a composition containing at least an alkali metal sulfide. In particular, it is preferable to sinter the phosphor in contact with at least two kinds of alkali metal sulfides of Li and Na in order to synthesize the phosphor of the present invention that is easily excited by near-ultraviolet light. Furthermore, by firing the phosphor in contact with two types of alkali metal sulfides of Li and Na and at least one alkali metal sulfide selected from K, Rb, and Cs, It is preferable because a phosphor having very high characteristics that can be excited in the wavelength region can be obtained, and among them, it is preferable to fire the phosphor in contact with three kinds of alkali metal sulfides of Li, Na, and K.

  Among them, it is preferable to make the number of moles of sodium sulfide larger than the total number of moles of sulfides of K, Rb, and Cs, and the number of moles of lithium sulfide is larger than the total number of moles of sulfides of K, Rb, and Cs. Increasing the size is also preferable. When the amount of lithium sulfide or sodium sulfide decreases, the crystal growth becomes insufficient and the characteristics of the phosphor tend to deteriorate. At least one alkali metal sulfide selected from K, Rb, and Cs is preferably brought into contact with the phosphor together with lithium sulfide and sodium sulfide during the firing of the phosphor, and is selected from K, Rb, and Cs. If at least one alkali metal sulfide is not present, sulfur is easily volatilized and the deposition ratio of the oxide phosphor increases, making it difficult to synthesize the oxysulfide phosphor. In addition, since it is easy to obtain the alkali metal sulfide used as a flux at high temperature by reaction with alkali metal carbonate and sulfur, it is preferable.

  In the light-emitting device of the present invention, the light-emitting device includes a first light-emitting body that generates light 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. When this phosphor contains the phosphor described above, a light emitting device with high luminous efficiency can be obtained. The wavelength of light generated by the first light emitter is 350 to 415 nm. However, from the viewpoint of the light emission characteristics of the phosphor, it is preferably 370 nm to 410 nm, and this affects the deterioration of the resin that holds the phosphor in the light emitting device. From the viewpoint of deterioration due to light from one light emitter, 390 to 415 nm is preferable, and when a GaN-based semiconductor light emitting element is used as the first light emitter, it is preferably 370 to 415 nm. From the viewpoint of these balances, the emission wavelength of the first light emitter that excites the phosphor is more preferably 370 nm to 415 nm, further preferably 370 nm to 410 nm, and most preferably 390 nm to 410 nm.

In the present invention, the first light emitter that irradiates the phosphor with light generates light having a wavelength of 350 to 415 nm. Specific examples of the first light emitter include a light emitting diode (LED) or a laser diode ( LD) and the like. 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. GaN-based LEDs and LDs preferably have an Al _x Ga _Y N light emitting layer, a GaN light emitting layer, or an In _x Ga _Y N light emitting layer. Among GaN-based LEDs, those having an In _X Ga _Y N light-emitting layer are particularly preferable because the emission intensity is very strong, and in GaN-based LDs, the multiple quantum of the In _X Ga _Y N layer and the GaN layer is preferred. A well structure is particularly preferable because the emission intensity is very strong. In the above, the value of X + Y is usually a value 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 constituent elements. The light-emitting layer is made of n-type and p-type Al _x Ga _y N layers, GaN layers, or In _x. Those having a heterostructure sandwiched between Ga _Y N layers and the like have high luminous efficiency, and those having a heterostructure having a quantum well structure have higher luminous efficiency and are more preferable.

  In the present invention, it is particularly preferable to use a surface-emitting type illuminant, particularly a surface-emitting GaN-based laser diode, as the first illuminant because the luminous efficiency of the entire light-emitting device is increased. A surface-emitting type illuminant is an illuminant that emits strong light in the surface direction of a film. In a surface-emitting GaN-based laser diode, the crystal growth of a light-emitting layer or the like is controlled, and a reflective layer or the like is successfully performed. By devising, the light emission in the surface direction can be made stronger than the edge direction of the light emitting layer. Compared with the type that emits light from the edge of the light emitting layer by using a surface emitting type, the light emission cross-sectional area per unit light emission amount can be increased. As a result, the phosphor constituting the second light emitting body is irradiated with the light. In this case, the irradiation area can be greatly increased with the same amount of light, and the irradiation efficiency can be improved, so that more intense light emission can be obtained from the phosphor.

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 type 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 that makes the contact. Contact here refers to creating a state in which the first light emitter and the second light emitter are in perfect contact with each other without air or gas. 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. 1 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. 1, 1 is a film-like second light emitter having the phosphor, 2 is a surface-emitting GaN-based LD as the first light emitter, and 3 is a substrate. To create a state of being in contact with each other, may be contacted by the adhesive or other means to each other in their surfaces keep in LD2 and a second light-emitting element 1 and the Ku are separately Nitsu, emission of LD2 a second light emitter on the surface may be a film (molded) is allowed to. 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 light emitter and the light from the second light emitter are usually directed in all directions, but when the phosphor powder used as the second light emitter is dispersed in the resin, the light is resin A part of the light is reflected when going out of the room, so that the direction of light can be adjusted to some extent. Accordingly, since light can be guided to a certain degree in an efficient direction, 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 in this case include epoxy resins, polyvinyl resins, polyethylene resins, polypropylene resins, polyester resins, and the like. From the viewpoint of good dispersibility of the phosphor powder, epoxy resins are preferable. It is. When the phosphor powder is dispersed in the resin, the weight ratio of the phosphor powder to the entire resin is usually 0.1 to 95%, preferably 1 to 20, more preferably 1 to 10%. is there. If the phosphor 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 or scattering by the resin.

  The light-emitting device of the present invention absorbs at least part of near-ultraviolet light or blue light from the first light emitter into the phosphor of the present invention, which is the second light emitter, and converts it into visible light, if necessary. Thus, light extracted from the light emitting device can be made white by mixing light from the blue light emitting phosphor and the green light emitting phosphor. At this time, the light from the first light emitter can also be mixed with the light from the phosphor. At this time, a color filter or the like may be used as necessary. By making the extracted light white light, the color rendering property of the object irradiated by the light emitting device is enhanced. This is particularly important when the light emitting device is applied to lighting applications.

In order to obtain a light emitting device capable of extracting white light using the present phosphor, in addition to the present phosphor, various blue-emitting phosphors and green-emitting phosphors that can be excited in a wavelength range of 350 nm to 415 nm. Combine. The blue light emitting phosphor and the green light emitting phosphor are not particularly limited as long as they can be excited in the wavelength range of 350 nm to 415 nm, but as the blue light emitting phosphor, (Ba, Sr, Ca, Mg) ₁₀ (PO ₄ ) ₆ (F, Cl) ₂ : Eu, (Ba, Sr, Ca, Mg) ₁₀ (PO ₄ ) ₆ (F, Cl) ₂ : Eu, Mn, (Ba, Sr, Ca) (Mg, Zn) Al ₁₀ O ₁₇ : Eu, (Ba, Sr, Ca) ₃ (Mg, Zn) Si ₂ O ₈ : Eu is preferable because of its high emission intensity, and the green light emitting phosphor is preferably SrAl ₂ O ₄ : Eu, Sr. ₄ Al ₁₄ O ₂₅ : Eu is preferable because of its high emission intensity.

  The light-emitting device of the present invention includes the phosphor as a wavelength conversion material and a light-emitting element that generates light of 350 to 415 nm, and the phosphor absorbs light of 350 to 415 nm emitted from the light-emitting element. In addition, it is a light emitting device that has good color rendering properties and can generate high-intensity visible light regardless of the use environment, and a light source such as a backlight light source and a traffic light, and an image display device such as a color liquid crystal display. And suitable for light sources such as lighting devices such as surface emitting.

  The light emitting device of the present invention will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view showing an embodiment of a light emitting device having a first light emitter (350 nm to 415 nm light emitter) and a second light emitter. 4 is a light emitting device, 5 is a mount lead, 6 is an inner lead, 7 is a first light emitter (350 nm to 415 nm light emitter), 8 is a phosphor-containing resin portion as a second light emitter, 9 Is a conductive wire, and 10 is a mold member.

  As shown in FIG. 2, 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 nm 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. 3, the surface emitting illumination device 98 incorporating the light emitting element 1 has a large number of light emission on the bottom surface of a rectangular holding case 910 whose inner surface is light opaque such as a white smooth surface. The device 91 is arranged with a power supply and a circuit (not shown) for driving the light emitting element 91 provided outside thereof, and a milky white acrylic plate or the like is provided at a position corresponding to the lid portion of the holding case 910. The diffusion plate 99 is fixed for uniform light emission.

  Then, the surface emitting illumination device 98 is driven to apply a voltage to the first light emitter of the light emitting element 91 to emit light of 350 to 415 nm, and a part of the light emission is used as the second light emitter. The phosphor in the phosphor-containing resin part absorbs and emits visible light, while light emission with high color rendering properties is obtained by mixing with blue light or the like that is not absorbed by the phosphor. 99 is emitted upward in the drawing, and illumination light with uniform brightness is obtained within the surface of the diffusion plate 99 of the holding case 910.

  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.

As shown in Table 1, each raw material is represented by molar ratio, La ₂ O ₃ is 0.9, Eu ₂ O ₃ is 0.1, Li ₂ CO ₃ is 1.2, Na ₂ CO ₃ is 1.2. , K ₂ CO ₃ is 0.6, sulfur powder is S and dry mixed at a ratio of 15 and the resulting mixture is placed in a high purity alumina crucible and covered with a tightly sealed alumina lid in a nitrogen gas atmosphere. By heating at 1300 ° C. for 2 hours, lithium sulfide, sodium sulfide, and potassium sulfide produced by the heating are contacted with lanthanum oxide and europium oxide as alkali sulfide flux to obtain oxysulfide, and these fluxes are subsequently The desired phosphor was obtained by continuous contact. The alkali sulfide flux adhering to the surface was removed by washing with water, and then dried at 140 ° C. to produce a phosphor (La _0.9 Eu _0.1 ) ₂ O ₂ S.

It was confirmed from the powder X-ray diffraction pattern of this phosphor that a phosphor containing no by-products was obtained. Next, using a fluorescence spectrophotometer F-4500 manufactured by Hitachi, Ltd., the red emission peak at 623 nm is monitored to obtain an excitation spectrum in the wavelength range of 300 nm to 450 nm, and the emission intensity ratio I ₄₀₀ / I _max is measured. As a result, it was 0.61, and the wavelength (peak wavelength) showing the maximum light emission intensity was 373 nm. Further, the product (α _q · η _i ) of the quantum absorption efficiency and the internal quantum efficiency when irradiated with excitation light having a wavelength of 400 nm was 0.37. The red phosphor, the blue phosphor Ba _0.7 Eu _0.3 MgAl ₁₀ O ₁₇ and the green phosphor Sr _0.9 Eu _0.1 Al ₂ O ₄ are mixed and weighed so that the total weight of the phosphor with respect to the epoxy resin is 8% by weight. After mixing and kneading and defoaming, the mixture was applied onto a light emitting diode chip having an emission wavelength of 405 nm to produce a white LED. This white LED exhibited good light emission characteristics with an average color rendering index of 89.

As shown in Table 1, phosphors were synthesized in the same manner as in Example 1 except that the ratio of La ₂ O ₃ was 0.85 and the ratio of Eu ₂ O ₃ was 0.15 (both molar ratios). . With respect to the obtained phosphor, I ₄₀₀ / I _max , peak wavelength, and α _q · η _i were measured. The results are shown in Table 1.

As shown in Table 1, phosphors were synthesized in the same manner as in Example 1 except that the ratio of La ₂ O ₃ was 0.7 and the ratio of Eu ₂ O ₃ was 0.3 (both molar ratios). . With respect to the obtained phosphor, I ₄₀₀ / I _max , peak wavelength, and α _q · η _i were measured. The results are shown in Table 1.
(Comparative Example 1)
As shown in Table 1, phosphors were synthesized in the same manner as in Example 1 except that the ratio of La ₂ O ₃ was 0.98 and the ratio of Eu ₂ O ₃ was 0.02 (both molar ratios). . With respect to the obtained phosphor, I ₄₀₀ / I _max , peak wavelength, and α _q · η _i were measured. The results are shown in Table 1.
(Comparative Example 2)
As shown in Table 1, each raw material is represented by molar ratio, La ₂ O ₃ is 0.85, Eu ₂ O ₃ is 0.15, KH ₂ PO ₄ is 0.3, Na ₂ CO ₃ is 1.05. Then, after dry-mixing the sulfur powder as S at a rate of 2.5, the resulting mixture was put into a high-purity alumina crucible, covered with a tightly sealed alumina lid, and heated at 1200 ° C. for 2 hours in a nitrogen gas atmosphere Thus, sodium sulfide and potassium phosphate produced by heating are contacted with lanthanum oxide and europium oxide as an alkali flux to obtain an oxysulfide, and then these fluxes are continuously contacted to obtain a desired phosphor. Got. After washing with water to remove the alkali flux adhering to the surface, it was dried at 140 ° C. to produce a phosphor (La _0.85 Eu _0.15 ) ₂ O ₂ S. With respect to the obtained phosphor, I ₄₀₀ / I _max , peak wavelength, and α _q · η _i were measured. The results are shown in Table 1.

Since the phosphor of the present invention has a large value of I ₄₀₀ / I _max , when used in a light-emitting device, even when the wavelength variation of the first light-emitting body showing the maximum light emission intensity near 400 nm occurs, Since the phosphor of the present invention, which is a light emitter, exhibits stable light emission intensity, it leads to stabilization of the light emission characteristics of the light emitting device, that is, even if the wavelength of the excitation source varies somewhat, it is not easily affected. In addition, since the phosphors of Examples 1 and 2 have large values of α _q · η _i and high light emission efficiency, a light emitting device using them becomes highly efficient.

DESCRIPTION OF SYMBOLS 1; 2nd light-emitting body 2; Surface emitting type GaN-type LED
DESCRIPTION OF SYMBOLS 3; Board | substrate 4; Light-emitting device 5; Mount lead 6; Inner lead 7; First light-emitting body 8; Resin part containing the fluorescent substance in this invention 9; Conductive wire 10;

Claims (7)

Ln source compound (wherein Ln represents an element that contains 50 mol% or more of La and may contain at least one element selected from Sc, Y, La, Gd, Lu, Bi), S A phosphor obtained by firing a source compound, an Eu source compound, in contact with three types of alkali metal sulfides of Li, Na, and K;
When the maximum emission intensity when irradiating excitation light within a wavelength range of 300 nm to 450 nm is I _max , and the emission intensity when irradiating excitation light with a wavelength of 400 nm is I ₄₀₀ , the emission intensity ratio I ₄₀₀ / _{I max} is Ri der 0.57 or more,
The following general formula [1]:
(Ln _1-x Eu _x ) ₂ O ₂ S [1]
(However, in the general formula [1], Ln has the same meaning as described above, and x is a number satisfying 0.07 ≦ x ≦ 0.35.)
A Ln ₂ O ₂ S: Eu phosphor comprising a crystal phase having the following chemical composition (excluding the crystal phases (1) to (4) below) :
(1) 180 g of La ₂ O ₃ and 34.3 g of Eu ₂ O ₃ are mixed, 3.6 g of LiNO ₃ is added as a Li source , and then 36.0 g of Li ₂ CO ₃ and Na ₂ CO, which is an auxiliary material, are added. Obtained by calcining a mixture prepared by charging 17.2 g of K ₃ , 9.0 g of K ₂ CO ₃ , 21.2 g of KH ₂ PO ₄ and 52.1 g of S at a maximum temperature of 1150 ° C. A crystal phase having a chemical composition of (La _0.85 , Eu _0.15 ) ₂ O ₂ S containing 170 ppm of Li and having an Eu concentration of 0.15 mol .
(2) 180 g of La ₂ O ₃ and 34.3 g of Eu ₂ O ₃ are mixed, 2.4 g of LiNO ₃ is added as a Li source , and then 24.0 g of Li ₂ CO ₃ and Na ₂ CO as an auxiliary material the mixture prepared by 52.1g charged ₃ 34.5g and _K 2 CO ₃ 9.0g and _KH 2 PO ₄ and 21.2g and S, obtained by sintering at a maximum temperature of 1150 ° C., A crystal phase having a chemical composition of (La _0.85 , Eu _0.15 ) ₂ O ₂ S containing 110 ppm of Li and having an Eu concentration of 0.15 mol .
(3) 180 g of La ₂ O ₃ and 34.3 g of Eu ₂ O ₃ are mixed, 0.96 g of LiNO ₃ is added as a Li source , and then 9.6 g of Li ₂ CO ₃ and Na ₂ CO as an auxiliary material ₃ , 55.1 g , K ₂ CO ₃ 9.0 g, KH ₂ PO ₄ 21.2 g, and 52.1 g of S, and a mixture prepared by firing at a maximum temperature of 1150 ° C. A crystal phase having a chemical composition of (La _0.85 , Eu _0.15 ) ₂ O ₂ S containing 90 ppm of Li and having an Eu concentration of 0.15 mol .
(4) 180 g of La ₂ O ₃ and 34.3 g of Eu ₂ O ₃ are mixed, 0.5 g of LiNO ₃ is added as a Li source , and then 18.1 g of Li ₃ PO ₄ and Na ₂ CO as an auxiliary material _The mixture was prepared by firing 68.9 g of K ₃ , 9.0 g of K ₂ CO ₃ and 52.1 g of S, and calcining at a maximum temperature of 1200 ° C., and the Eu concentration containing 130 ppm of Li was 0. Crystal phase having a chemical composition of 15 mol (La _0.85 , Eu _0.15 ) ₂ O ₂ S. 2. The phosphor according to claim 1, wherein in three types of alkali metal sulfides of Li, Na, and K, the number of moles of Na sulfide is larger than the number of moles of K sulfide. 3. The phosphor according to claim 1, wherein, in three types of alkali metal sulfides of Li, Na, and K, the number of moles of Li sulfide is larger than the number of moles of K sulfide. The phosphor according to any one of claims 1 to 3, wherein in the general formula [1], Ln is La. In a light-emitting device including a first light emitter that generates light 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 includes: A light-emitting device comprising the phosphor according to claim 1. An image display device comprising the light emitting device according to claim 5. Lighting apparatus characterized by having a light-emitting device according to claim 5.

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