JP5399617B2 - Luminescent composition, light source device using the same, and display device using the same - Google Patents

Description

  The present invention relates to a light-emitting composition having a phosphor, and in particular, to improve the moisture resistance of a silicate phosphor and have a stable light emission luminance over time, and to use this light-emitting composition and a blue light source The present invention relates to a conventional light source device and a display device using the light source device.

  The phosphor is a light emitting material whose emission wavelength band changes according to the type and composition ratio of its constituent elements, and a phosphor having a desired emission wavelength band can be selected. The phosphor can be applied to a thin display device called a so-called FPD (Flat Panel Display) such as a liquid crystal display (LCD), a plasma display, and an organic EL (Electro Luminescence) display. It is being considered.

  These display devices usually have a light source device such as a backlight. Recently, light emitting diodes (LEDs (Light-Emitting Diodes) (LEDs) having features such as small size (small occupied area), low power consumption, high-speed response, and long life are provided. Emitting Diode)), for example, a light source device (white LED) that emits white light by combining a blue LED that emits blue light and a phosphor that emits fluorescence of a predetermined wavelength band has been attracting attention.

  The light source device using a blue LED can simplify the drive circuit compared to a configuration in which all three colors of red light, blue light, and green light are obtained by a direct drive light source such as an LED, and can emit ultraviolet light to near ultraviolet light. Suppresses the deterioration of members (resins, LED chips, etc.) that make up the light source device compared to a configuration that uses a plurality of phosphors to emit red light, blue light, and green light as an excitation light source such as an emitted LED. It has the advantage of being able to do so.

  Light source devices using blue LEDs are being considered for use in various applications such as LCD backlights, decorative lighting, flashlights, automobile headlights, medical endoscope lighting, and surgical lighting. Yes.

  Light source devices (light emitting devices) that emit white light using LEDs include the following methods. In the following description of the specification, “phosphor that emits fluorescence in the yellow region” is abbreviated as “yellow phosphor”, and “phosphor that emits fluorescence in the red region” is abbreviated as “red phosphor”. The “phosphor that emits fluorescence in the green region” is abbreviated as “green phosphor”.

  (1) White light is emitted by mixing yellow light emitted by exciting a yellow phosphor (for example, YAG (Yttrium Aluminum Garnet)) with a blue LED that emits blue light and blue light emitted by the blue LED. (For example, see Patent Document 1 below.)

  (2) White light is emitted by mixing yellow light and red light emitted by exciting a yellow phosphor (for example, YAG) and a red phosphor with a blue LED, and blue light by a blue LED (for example, (See Patent Document 2 below.)

  (3) White light is emitted by mixing red light and green light emitted by exciting a red phosphor and a green phosphor with a blue LED and blue light from the blue LED (for example, Patent Document 3 described later) , See Patent Document 5).

  (4) A yellow phosphor, a green phosphor, and a red phosphor are combined with a blue LED, and white light is mixed by mixing yellow light, green light, and red light excited by the blue LED with blue light emitted by the blue LED. (See, for example, Non-Patent Document 1 below).

  (5) White light is emitted by mixing red light, blue light, and green light emitted by exciting three or more kinds of phosphors with LEDs that emit ultraviolet light to near ultraviolet light (for example, described later) (See Patent Document 4).

  (6) White light is emitted by mixing blue light, red light, and green light by each of the three LEDs, a blue LED that emits blue light, a red LED that emits red light, and a green LED that emits green light. (For example, see Patent Document 5 below.)

  (7) A phosphor such as a halophosphate conventionally developed for fluorescent lamps is excited by an ultraviolet LED to emit white light.

  Each of the above methods has advantages and disadvantages. For example, the methods (1) to (4) can be simplified in structure as compared with the method (6). The drive circuit can be simplified, and the purple-near-ultraviolet of the members constituting the light source device (for example, phosphor, resin, LED chip, etc.) as compared with the methods (5) and (7). Deterioration due to light can be suppressed. The systems (1) to (4) are considered to be suitable for lighting devices used for various applications and light source devices that realize white illumination of display devices.

  Light source devices that realize white illumination of lighting devices and display devices used in the various applications described above are required to be small in size, high in brightness, long in life, low in price, low in power consumption, and the like. Therefore, for example, various materials constituting the light source device such as a phosphor material, a sealing resin material, a coating resin material, and an LED chip material are required to have moisture resistance and light resistance over a long period of time.

  Hereinafter, a conventional technique related to moisture resistance and light resistance in a light source device that emits white light using an LED will be described.

  Patent Document 1 below entitled “Light Emitting Diode” has the following description.

  Photoluminescent phosphor powder may be contained in a resin or glass and formed thin enough to allow light from the LED chip to pass through. Similarly, a photoluminescent phosphor powder may be contained in a resin or glass and formed thin enough to allow light from the LED chip to pass through.

  Patent Document 2 below titled “Light Emitting Diode” has the following description.

  The light emitting diode comprises an LED chip that emits blue visible light, a YAG phosphor that emits yellow visible light, and a red phosphor that emits red visible light, the blue visible light, It is configured to emit white light by mixing yellow visible light and red visible light.

  Since the light emitting diode includes a red phosphor together with the YAG phosphor, the red visible light emitted from the red phosphor can make up for the shortage of the red component of the YAG phosphor, thereby improving the color rendering of the light emitting diode. Can be improved.

  14 (A), 14 (B), 14 (C), and 14 (D) are respectively FIGS. 1, 2, 3, and 4 described in Patent Document 2, and the LED will be described. FIG. 14A is a schematic cross-sectional view of the first LED, FIG. 14B is a schematic cross-sectional view of the second LED, and FIG. 14C is an enlarged schematic view showing an example of a red phosphor coated with glass. FIG. 14D is an enlarged schematic cross-sectional view showing an example of a YAG phosphor and a red phosphor coated with glass.

  FIG. 14A is a schematic cross-sectional view showing the first LED 110. The first LED 110 is directed upward from the bottom surface to the tip end portion 112a of the first lead frame 112 for mounting the LED chip. A substantially funnel-shaped concave portion with a gradually increasing hole diameter is provided, and the reflector 114 is formed by forming the inner surface of the concave portion as a reflective surface. On the bottom surface of the reflector 114, an LED chip 116 that emits blue visible light is provided. The first lead frame 112 and one electrode (not shown) on the bottom surface of the LED chip 116 are electrically connected to each other by die bonding via Ag paste or the like.

  Further, the front end portion 118 a of the second lead frame 118 and the other electrode (not shown) on the upper surface of the LED chip 116 are electrically connected via a bonding wire 120. The LED chip 116 emits blue or blue-violet visible light having a wavelength of 410 nm to 490 nm and is made of, for example, a gallium nitride semiconductor crystal.

  The upper and side surfaces of the LED chip 116 are covered and sealed with a coating material 122 filled in the reflector 114. The coating material 122 is made of an inorganic material such as glass having translucency. Unlike organic materials such as epoxy resin, inorganic materials such as glass hardly absorb short-wavelength light with large energy, and even when short-wavelength light is absorbed, it deteriorates due to its strong molecular bonding force. There is almost no.

  For this reason, the coating material 122 that covers the LED chip 116 is made of an inorganic material, so that deterioration and discoloration of the coating material 122 due to short-wavelength light with large energy emitted from the LED chip 116 is prevented. There is no decrease in luminous intensity or color tone of the LED 110 due to deterioration or discoloration.

Further, in the coating material 122, the YAG phosphor 124 that converts the light emitted from the LED chip 116 into visible yellow light of about 560 nm to about 590 nm, and the red light of about 600 nm to about 780 nm is emitted from the LED chip 116. A large number of red phosphors 126 which are converted into visible light of the system are mixed in a dispersed state. Examples of the YAG phosphor 124 include (Y, Gd) ₃ Al ₅ O ₁₂ : Ce, Y ₃ Al ₅ O ₁₂ : Ce, and the like.

  The red phosphor 126 is preferably a sulfide-based phosphor such as (Zn, Cd) S: Ag, (Zn, Cd) S: Ag, Cl, ZnS: Mn, CaS: Eu. is there. The sulfide-based phosphor is a phosphor that can easily obtain a wide range of emission wavelengths such as red, green, and blue by changing the proportions of the constituent components.

  When the coating material 122 is made of glass as an inorganic material, so-called sol-gel glass produced using a sol-gel method capable of synthesizing glass at a relatively low temperature can be used.

  The LED chip 116 covered with the coating material 122, the top ends 112a and 112b of the first lead frame 112, and the top ends 118a and 118b of the second lead frame 118 are convex lenses at the tips. It is covered and sealed with a translucent resin material 130 made of an epoxy resin or the like having a portion 128.

  Further, the lower ends of the terminal portion 112b of the first lead frame 112 and the terminal portion 118b of the second lead frame 118 pass through the lower end portion of the translucent resin material 130 to the outside of the translucent resin material 130. Has been derived.

  FIG. 14B is a schematic cross-sectional view showing the second LED 132, and the second LED 132 includes the red phosphor 126 (Zn, Cd) S: Ag, (Zn, Cd) S: Ag, It is composed of a sulfide-based phosphor such as Cl, ZnS: Mn, and CaS: Eu, and is characterized in that the red phosphor 126 is covered with a non-water-permeable glass 134 as a moisture-resistant material having translucency. It is what has.

  That is, as shown in an enlarged view in FIG. 14C, the sulfide-based red phosphor 126 is covered with the glass 134. When the red phosphor 126 is covered with the glass 134, the number of red phosphors 126 covered with one glass 134 is different.

  As shown in FIG. 14D, the YAG phosphor 124 and the red phosphor 126 are both coated with a glass 134, and the YAG phosphor 124 and the red phosphor 126 coated with the glass 134 are coated with a coating material. It may be mixed in 122.

  In the second LED 132, the red phosphor 126 made of a sulfide-based phosphor is coated with the glass 134 in order to improve the moisture resistance of the red phosphor 126. That is, the sulfide-based phosphor has an advantage that a wide range of emission wavelengths can be easily obtained by changing the proportion of the constituent components, but has a disadvantage that it is inferior in moisture resistance.

  For this reason, when an LED using a sulfide-based phosphor is used in a high-humidity environment, the sulfide-based phosphor is in the air that has entered the interior from the surface of the translucent resin material. In some cases, it reacts with moisture and the light from the LED chip to cause photodecomposition, deposits a constituent metal element such as zinc metal on the surface, and changes its color to black or the like, resulting in a decrease in brightness of the LED.

  Therefore, in the second LED 132, the red phosphor 126 composed of a sulfide-based phosphor is covered with a non-water-permeable glass 134 as a moisture-resistant material so as to enter the second LED 132. This prevents moisture from adhering to the red phosphor 126, thereby preventing a decrease in luminance due to moisture degradation of the red phosphor 126 made of sulfide-based phosphor.

  Patent Document 4 below entitled “Light Emitting Diode” has the following description.

  The light-emitting diode is a light-emitting diode comprising an LED chip, phosphor particles for red light emission, phosphor particles for green light emission, phosphor particles for blue light emission, and fluorescent glass, and the fluorescent glass Among the phosphor particles for red light emission, the phosphor particles for green light emission, and the phosphor particles for blue light emission, the emission color of the phosphor particles having lower emission luminance than the other phosphor particles is the same as or It has the same luminescent color.

  The LED chip is disposed on one surface of the substrate, and the LED chip is covered with a coating material composed of the fluorescent glass. In the coating material, the phosphor particles for red light emission and the green light emission material are coated. The light emitting diode can be configured by mixing phosphor particles and phosphor particles for blue light emission.

  Further, the LED chip is disposed on one surface of the substrate, and the LED chip is covered with a coating material having translucency, and the fluorescent material for red light emission coated with the fluorescent glass in the coating material. The light emitting diode may be configured by mixing body particles, phosphor particles for green light emission coated with the fluorescent glass, and phosphor particles for blue light emission coated with the fluorescent glass.

  Patent Document 6 below titled “Light Emitting Element” has the following description.

  An object of the invention of Patent Document 6 is to provide a light-emitting element having an improved service life provided with a light-emitting diode and a fluorescent layer.

  This object is achieved by a light emitting device characterized in that it comprises at least one light emitting diode and a phosphor layer, the phosphor comprising at least one phosphor having a coating. Deterioration caused by moisture in the air is prevented by the coating of phosphor particles having a high-density water-resistant film.

  Preferably, the coating is selected from the group consisting of organic materials, inorganic materials and glass materials. More preferably, the organic material is selected from the group consisting of latex and polyorganosiloxane. More preferably, the glass material is selected from the group consisting of borosilicate, phosphosilicate, and alkali silicate. More preferably, the inorganic material is selected from the group consisting of oxides, borates, phosphates and combinations of these materials.

  These organic, glass and inorganic materials form a thin and insoluble coating on the phosphor particles that does not react with the phosphor and UV radiation, ie 410-450 nm. Is not degraded by radiation having a wavelength of. Furthermore, the coating is colorless and therefore does not affect the phosphor color value.

  FIG. 15 is a diagram illustrating a light-emitting element in FIG. 1 described in Patent Document 6.

  As shown in FIG. 15, the light emitting element 101 includes a diode 103 that emits UV radiation or blue light and a fluorescent layer 102 provided in the diode 103 in the simplest case. The fluorescent layer 102 includes a transparent layer 105 having a phosphor 104 with a water resistant coating. The material of the transparent layer 105 can be, for example, polyacrylate, polystyrol, epoxy resin, polypropylene, polycarbonate, or some other polymer.

  A light emitting device 101 such as a mass-produced product is usually protected by an epoxy housing 106 on which an epoxy resin lens is molded. This lens plays a role of improving the guidance of light from the light emitting element 101. The fluorescent layer 102 may be provided between the transparent layer 105 and the epoxy housing 106. The fluorescent layer 102 can also be provided as a coating on the outside of the epoxy housing 106.

  In these cases, the phosphor layer 102 comprises a phosphor mixture comprising a phosphor 104 provided with a coating. In another embodiment, the phosphor layer 102 is formed from an epoxy resin and the phosphor 104 is provided with a coating. In the embodiment of Patent Document 6, the fluorescent layer 102 forms an epoxy housing 106.

  The phosphor used in the phosphor layer 102 is, for example, an oxidized phosphor, a sulfurized phosphor, an aluminate phosphor, a borate phosphor, a vanadate phosphor, or a silicate phosphor. The particles of the phosphor 104 are covered with a thin and flat water-resistant layer. The thickness of the waterproof coating layer is typically 0.001-0.2 μm and is therefore very thin so that photons can pass through the layer with little loss of energy.

  The above is description regarding the prior art regarding moisture resistance and light resistance in the light source device which radiate | emits white light using LED.

Among the silicate phosphors, phosphors having a composition represented by Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2) are excited by light from the blue region to near ultraviolet. Thus, it is a phosphor that generates fluorescence in a blue-green region to a yellow region, and in recent years, application to white LEDs is also expected.

Hereinafter, the silicate phosphor used in the light source device will be described.
Patent Document 7 described later entitled “Liquid Crystal Display” and Patent Document 8 named “Semiconductor Light-Emitting Element Unit” include a composition (SrBaMgM) as a wavelength conversion material that can be excited by ultraviolet rays and generate green light. ) ₂ SiO ₄ : Europium activated alkaline earth silicate phosphor of Eu is described.

  Patent Document 9 below titled “Phosphor and Light-Emitting Device Using the Same” has the following description.

(A) the composition _{formula: (Ba a Ca b Sr c} Mg d Eu x) in the phosphor consisting of europium-activated alkaline earth metal silicate represented by SiO _4, in this composition formula, coefficients a, b, c , D and x satisfy a + b + c + d + x = 2, 0 <a <2, 0 <b <2, 0 ≦ c <1.0, 0 ≦ d <0.9, 0 <x ≦ 0.5, and A phosphor characterized in that 50% or more of all Eu ions are Eu ²⁺ ions. (B) The phosphor according to (a), which emits blue or green light.

  Patent Document 10 below entitled “Semiconductor Light-Emitting Device” has the following description.

(Me _1-y Eu _y ) ₂ SiO ₄ (Me is at least one element selected from Ba, Sr, Ca, and Mg, 0 <y ≦ 1) Thus, a yellow phosphor and an orange phosphor are respectively configured.

Japanese Patent No. 2927279 (paragraphs 0019 to 0021) JP 2004-152993 A (paragraphs 0007 to 0008, paragraphs 0011 to 0017, paragraphs 0021 to 0023, paragraph 0029, FIGS. 1 to 4) Japanese translation of PCT publication No. 2004-505172 (paragraphs 0006-0021) JP-A-2004-88011 (paragraphs 0007 to 0010, paragraphs 0014 to 0020, paragraph 0024, paragraphs 00003 to 0031, FIGS. 1 to 4) JP 2001-184921 A (paragraphs 0020-0023, paragraphs 0038-0041) JP 2002-223008 A (paragraphs 0006 to 0013, paragraphs 0023 to 0024, paragraphs 0028 to 0029, FIG. 1) JP 2006-91896 A (paragraph 0014) JP 2006-93711 A (paragraph 0051) JP2007-23129 (paragraphs 0008 to 0009) JP 2007-59898 A (paragraph 0012) Hirosaki et al., “White LED for Lighting”, Fujikura Technical Report, No. 109, pp. 1-4 (2005) (5. Luminescent characteristics of white LED using nitride phosphor)

  Conventionally, in order to take measures against moisture resistance of a light source device that emits white light by mixing blue light emitted from a blue LED and fluorescence emitted by exciting a phosphor with the blue light, the moisture resistance is high. The use of the considered oxide phosphors and nitride phosphors, and the use of sulfide phosphors coated to improve moisture resistance have been studied.

  Various studies have been made on coatings for improving the moisture resistance of sulfide phosphors, but there are few reports on specific data showing the improvement of moisture resistance by coating. Conventionally, oxide phosphors and nitride phosphors are considered to have high stability. Regarding these phosphors, there are no reports on specific results of actually improving the moisture resistance by coating. Absent.

  A light source device (white LED) that emits white light by mixing a fluorescent light having different fluorescence wavelengths (colors) emitted by excitation of a plurality of types of phosphors with blue light emitted from a blue LED and a blue light emitted for a long time. In order to enable stable driving over a wide range, the improvement in the moisture resistance of the phosphor is very important along with the improvement in the light resistance of the members constituting the light source device. When the emission intensity of a phosphor changes with time due to temperature, humidity, ultraviolet light, etc., the emission luminance of the light emitted from the light source device changes with time, and the emission spectrum of the light emitted from the light source device also changes over time. As a result, the chromaticity of the white light emitted from the light source device changes, resulting in a problem that the color rendering is deteriorated.

The silicate phosphor having a composition represented by Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2) has an excitation efficiency by light in the blue region, and an excitation efficiency by near ultraviolet light. There is a problem that extremely low compared _{to, Sr x Ba 2-x SiO} 4: in the light source device excited by light in the blue region of the Eu, efficiency of excitation by light in the blue region is strongly demanded.

Further, the reliability of Sr _x Ba _2-x SiO ₄ : Eu regarding moisture resistance has not been studied so far.

  The present invention has been made in order to solve the above-described problems, and its object is to improve the moisture resistance of a silicate phosphor and to have a light-emitting composition having stable emission luminance over time, and An object of the present invention is to provide a light source device using the luminescent composition and a blue light source, and a display device using the light source device.

That is, the present invention relates to at least one magnesium salt selected from the group consisting of magnesium chloride, magnesium carbonate, magnesium sulfate, and magnesium fluoride, and Sr _x Ba _2-x SiO ₄ : Eu (where 0 ≦ x ≦ 2). A glass layer containing at least silicon (Si) and oxygen (O) on the surface of a phosphor composition obtained by mixing with a phosphor that is excited by blue light represented by The present invention relates to a luminescent composition in which is formed.

  The present invention also provides the light-emitting composition, the first light-emitting composition having the phosphor as the first phosphor, the second light-emitting composition containing the second phosphor, and blue light. A green light source emitting from the first phosphor excited by the blue light, and a fluorescence emitted from the second phosphor excited by the blue light. And a light source device that emits white light by mixing the blue light.

  In addition, the present invention includes the light source device, and the light source device relates to a display device that irradiates a pixel portion in which a plurality of pixels are arranged.

According to the light-emitting composition of the present invention, it has a composition represented by Sr _x Ba _2-x SiO ₄ : Eu (where 0 ≦ x ≦ 2) to which a magnesium salt is added, and emits blue light. Since a glass layer containing at least silicon (Si) and oxygen (O) is formed on the surface of the phosphor that is excited and emits fluorescence in the green region, Sr _x Ba _2−x SiO ₄ : Eu (provided that 0 ≦ x ≦ 2) Excitation efficiency is improved by the magnesium (Mg) salt added to the phosphor, and the moisture-impermeable and transparent glass layer formed on the surface suppresses characteristic deterioration due to humidity. It is possible to provide a light-emitting composition that can suppress a decrease in the intensity of fluorescence in the green region excited and emitted by the blue light, has excellent moisture resistance, and has stable emission luminance over time. it can. Moreover, the light source device which has the outstanding performance is realizable by combining the said luminescent composition and the blue light source which radiate | emits blue light.

  According to the light source device of the present invention, the light-emitting composition is a first light-emitting composition that includes the phosphor as a first phosphor, and a second light-emitting composition that includes a second phosphor. A blue light source that emits blue light, fluorescence in the green region emitted from the first light emitting composition excited by the blue light, and the second light emitting composition excited by the blue light The first light-emitting composition has an excitation efficiency due to the Mg salt added to the first phosphor because the blue light and the blue light are mixed to emit white light. Since the impermeable glass layer is formed on the surface of the first light emitting composition, the deterioration of characteristics due to the humidity of the first light emitting composition can be suppressed, and the moisture resistance is excellent. And the first light emitting composition is excited by the blue light. A light source that can suppress a decrease in the intensity of fluorescence in the green region, can emit white light having excellent moisture resistance and stable emission luminance and chromaticity over time, and has excellent luminous performance An apparatus can be provided. Moreover, the light source device which has arbitrary desired chromaticity can be easily provided by changing the mixing ratio of the said 1st luminescent composition and the said 2nd luminescent composition.

  According to the display device of the present invention, the light source device includes the light source device, and the light source device irradiates a pixel portion in which a plurality of pixels are arranged. Therefore, characteristic deterioration due to humidity of the first light emitting composition is suppressed. A display device that can perform stable display and has excellent moisture resistance and stable luminance and chromaticity with time can be provided.

  In the luminescent composition of the present invention, the magnesium salt preferably includes at least one of magnesium chloride, magnesium carbonate, magnesium sulfate, and magnesium fluoride. According to this configuration, by adding the magnesium salt to the phosphor, it is possible to obtain a light emitting composition having a light emission intensity higher than that of the phosphor alone.

  In addition, a value of (intensity at a wavelength of 450 nm) / (intensity at a wavelength of 370 nm) regarding the excitation spectrum is preferably 0.67 or more and 0.83 or less. According to this configuration, when the excitation spectrum of the luminescent composition is compared with the excitation spectrum of the phosphor alone, the excitation spectrum of the luminescent composition (excitation intensity at an excitation wavelength of 450 nm) / (excitation intensity at an excitation wavelength of 370 nm). ) Is larger than the value of (excitation intensity at an excitation wavelength of 450 nm) / (excitation intensity at an excitation wavelength of 370 nm) related to the excitation spectrum of the phosphor alone, which is higher than that of the phosphor alone. A light emitting composition having excellent light emission characteristics with improved excitation efficiency at a wavelength of 450 nm can be obtained.

  In addition, the intensity at a wavelength of 450 nm related to the excitation spectrum is preferably 1.5 times or more and 2.1 times or less as compared with the intensity at a wavelength of 450 nm in the single phosphor. According to this configuration, the shape of the excitation spectrum changes depending on whether or not the magnesium salt is added, and the excitation efficiency at the excitation wavelength of 370 nm and the excitation efficiency at the excitation wavelength of 450 nm are both improved compared to the phosphor alone. A luminescent composition having excellent luminescent properties can be obtained.

  Moreover, it is good to set it as the structure which the addition amount of the said magnesium salt is a ratio of 1 mol or more and 30 mol or less with respect to 100 mol of said fluorescent substance. According to this configuration, it is possible to obtain a light emitting composition having a light emission intensity that is twice or more that of the single phosphor.

  Moreover, it is good to set it as the structure which the addition amount of the said magnesium salt is a ratio of 3 mol or more and 15 mol or less with respect to 100 mol of said fluorescent substance. According to this configuration, a light emitting composition having a light emission intensity 2.3 times or more that of the phosphor alone can be obtained.

  In addition, the Eu concentration is preferably 1 mol% or more and 9 mol% or less. According to this configuration, it is possible to provide a light emitting composition having good light emission intensity.

  In addition, the Eu concentration is preferably 2 mol% or more and 5 mol% or less. According to this configuration, a light emitting composition having better light emission intensity can be provided. When the Eu concentration is less than 2 mol% and more than 5 mol%, the emission intensity is lowered, and good emission intensity cannot be obtained.

  In the light source device of the present invention, it is preferable that the second light-emitting composition is a phosphor that emits red region fluorescence when excited by the green region fluorescence and the blue light. According to this configuration, since the glass layer is formed on the surface of the first light-emitting composition, it is possible to suppress deterioration of characteristics due to humidity of the first light-emitting composition, and the blue light A decrease in the intensity of the fluorescence in the red region emitted by the excitation of the second light-emitting composition due to the fluorescence in the front green region emitted by the excitation of the first light-emitting composition can be suppressed. Since the deterioration of the fluorescence intensity of the green region is suppressed, the fluorescence intensity of the red region excited from the second light emitting composition by the fluorescence of the green region does not decrease. By mixing the fluorescence and the red region, it is possible to emit white light having stable emission luminance and chromaticity over time, and to provide a light source device having excellent light emission performance.

In addition, the second phosphor is preferably composed of CaAlSiN ₃ : Eu. According to this configuration, CaAlSiN ₃ : Eu is excellent in moisture resistance and can be used alone.

  The glass layer is preferably formed on the surface of the second phosphor. According to this configuration, when the moisture resistance of the second phosphor is not good, the moisture resistance of the second phosphor can be improved.

  In the display device according to the aspect of the invention, it is preferable that the light source device is a backlight that irradiates the pixel portion from the back surface. According to this configuration, the light source device can be used as a backlight device of a display device such as a liquid crystal display, and the luminance and chromaticity stable over time regardless of the humidity history of the environment where the display device is placed. Thus, a display device having excellent performance can be provided.

The method for producing a light-emitting composition of the present invention includes a first step of adjusting a phosphor having a composition represented by Sr _x Ba _2-x SiO ₄ : Eu (where 0 ≦ x ≦ 2). And a second step of adding a magnesium salt to the phosphor and a third step of forming a glass layer covering the entire surface of the phosphor to which the magnesium salt has been added.

  In the second step, at least one of magnesium chloride, magnesium carbonate, magnesium sulfate, and magnesium fluoride is added as the magnesium salt at a ratio of 40 mol or less, preferably 30 mol, relative to 100 mol of the phosphor. In the third step, the glass layer is formed by a sol-gel method.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

  Light source devices used as lighting devices for various applications are required to maintain stable emission luminance and chromaticity over time, and the emission luminance and chromaticity are stable under changing environmental conditions such as temperature and humidity. It is required to emit white light whose color rendering property is kept constant.

  In general, in addition to the reliability test at normal temperature and humidity, the light source device needs to clear the reliability test under more severe conditions such as a temperature of 60 ° C. or higher and a humidity of 90% RH (Relative Humidity) or higher. is there.

A luminescent composition according to the present invention comprises a phosphor (Eu-activated alkaline earth silicate phosphor) having a composition of Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2), The glass layer which has Mg salt added to this fluorescent substance and has silicon (Si) and oxygen (O) on the surface of the light emitting composition is formed. This luminescent composition is excited by light in the blue region and emits fluorescence in the green region, and the concentration of Eu is 1 mol% or more and 9 mol% or less, and preferably 2 mol% or more and 5 mol% or less. The amount of Mg salt that is a magnesium-based additive is 1 mol or more and 30 mol or less, preferably 3 mol or more and 15 mol or less, with respect to 100 mol of the phosphor. The Mg salt includes at least one of magnesium chloride, magnesium carbonate, magnesium sulfate, and magnesium fluoride. The value of (intensity at excitation wavelength 450 nm) / (intensity at excitation wavelength 370 nm) relating to the excitation spectrum of this luminescent composition is 0.67 or more and 0.83 or less, and the intensity at excitation wavelength 450 nm relating to the excitation spectrum is Compared to the intensity at a wavelength of 450 nm in the single phosphor, it is 1.5 times or more and 2.1 times or less.

A light source device according to the present invention is the above-described luminescent composition, the first luminescent composition having the phosphor as the first phosphor, the second luminescent composition containing the second phosphor, A blue light source that emits light in the blue region, and fluorescence in the green region emitted from the first light emitting composition excited by the light in the blue region, and second light emitting composition excited by the light in the blue region The fluorescent light emitted from the object and the light in the blue region are mixed to emit white light. The second light-emitting composition includes a second phosphor that emits red region fluorescence when excited by green region fluorescence and blue region light, and the second phosphor is, for example, CaAlSiN ₃ : Eu. . The glass layer may be formed on the surface of the second phosphor.

  According to the present invention, a luminescent composition that improves the moisture resistance of a silicate phosphor and has stable emission luminance over time, a light source device using the luminescent composition and a blue light source, and the light source device Can be provided as a backlight device.

FIG. 1 is a cross-sectional view illustrating a light-emitting composition and a light source device using the same according to an embodiment of the present invention, and CaAlSiN ₃ : Eu and a phosphor (magnesium-based additive) having a glass layer formed on the surface. those in which Sr Mg salt is added _{x Ba 2-x SiO 4:} Eu (. proviso that 0 ≦ x ≦ 2)) is a diagram illustrating a light source device (white LED) using a. Hereinafter, the luminescent composition and the light source device will be described.

  The light source device 40 according to the present embodiment includes a blue LED 28 that emits light in a blue region, a first luminescent composition 38, and a second luminescent composition 24.

The first luminescent composition 38 is composed of particles of Sr _x Ba _2−x SiO ₄ : Eu (first phosphor (green phosphor, where 0 ≦ x ≦ 2) 20 to which an Mg salt is added. The transparent light-impermeable glass layer 22 containing silicon (Si) and oxygen (O) is formed on the entire surface of the first light emitting composition 38. The first light emitting composition 38 is emitted from the blue LED 28. It is excited by light in the blue region and emits fluorescence in the green region.

For example, the first light emitting composition 38 includes a phosphor having a composition SrBaSiO ₄ : Eu in which the composition Sr _x Ba _2−x SiO ₄ : Eu has x = 1.0 and the Eu concentration is 3 mol%, And an Mg salt (for example, magnesium chloride) added at a ratio of 1 mol or more and 30 mol or less, preferably 3 mol or more and 15 mol or less with respect to 100 mol of the phosphor, and the entire surface of the particles of the composition Is covered by a glass layer 22.

The second light emitting composition is composed of a second phosphor (red phosphor: CaAlSiN ₃ : Eu) 24 alone, and the second phosphor 24 is excited by the light in the blue region and emits fluorescence in the red region. To do. Further, as shown in FIG. 1, the second phosphor 24 is excited by the green region fluorescence emitted from the first light emitting composition 38 and emits the red region fluorescence.

  The first light emitting composition 38 and the second light emitting composition (second phosphor 24) are mixed at a predetermined weight ratio (for example, 95: 5) and dispersed in the transparent resin. After that, the white LED 40 was configured by potting on the blue LED 28.

  In the light source device 40, the blue region light emitted from the blue LED 28, the green region fluorescence emitted from the first light emitting composition 38, and the red region fluorescence emitted from the second light emitting composition are mixed. It is a white LED that emits white light.

  As shown in FIG. 1, the electrode of the blue LED 28 is connected to the driving electrodes 30 and 32 of the substrate 34, and the blue LED 28 is mounted on the substrate 34. The blue LED 28 is disposed at the bottom of the recess of the package 36 having a recess and the inner surface of which forms a reflection surface. The package 36 also serves as a reflector.

The blue LED 28 is covered with a transparent resin 26 in which a first light emitting composition 38 and CaAlSiN ₃ : Eu (second light emitting composition) 24 are dispersed.

  As the transparent resin 26, various transparent resins can be used in addition to epoxy, silicone, and urethane.

The blue LED 28 is composed of, for example, a GaN-based semiconductor, a ZnO semiconductor, or the like. White light is emitted from the light source device 40 by mixing the blue region light, the green region fluorescence, and the red region fluorescence emitted from the blue LED 28. The chromaticity of the white light is dispersed in the transparent resin 26. The first light-emitting composition 38 and CaAlSiN ₃ : Eu (second light-emitting composition) 24 can be arbitrarily set.

  The white LED according to the present embodiment is used as a lighting device for portable electronic devices such as mobile phones and game devices, and liquid crystal display devices such as televisions and personal computers. Although FIG. 1 shows a surface-emitting light source device, a bullet-type or edge-emitting light source device may be used.

  In the present embodiment, the first light-emitting composition 38 is composed of the first phosphor particles (green phosphor 20) to which Mg salt is added and the glass layer 22 formed on the surface thereof, and has excellent moisture resistance. Therefore, it is possible to suppress the deterioration of characteristics due to the humidity of the green phosphor 20, and it is excited by the fluorescence in the green region emitted from the green phosphor 20, and is emitted from the second phosphor (red phosphor 24). The decrease in the fluorescence intensity of the red region can be suppressed, and the decrease in the emission efficiency of the fluorescence in the red region from the red phosphor 24 can be suppressed, so that stable emission luminance and chromaticity can be obtained over time. It is possible to realize the light source device 40 that emits white light and a display device having the same.

In addition to Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2) to which Mg salt is added as a green phosphor, silicate phosphor (Eu activation (Ba, Sr) , Ca, Mg) ₂ SiO ₄ phosphor) can also be used. In addition to CaAlSiN ₃ : Eu, a sulfide phosphor or the like can be used as the red phosphor, and the glass layer 22 may be formed on the surface of the red phosphor.

In the light source device 40 according to the present embodiment, a Mg salt is added to a phosphor having a composition represented by Sr _x Ba _2-x SiO ₄ : Eu (where 0 ≦ x ≦ 2), The glass layer 22 is formed on the surface to form the light emitting composition 38. With this configuration, excitation is improved in both the near ultraviolet light and the blue region, and the blue region is more than the excitation by the near ultraviolet light. The improvement of the excitation efficiency with respect to the excitation by the light of is intended.

  According to the light emitting composition 38 in which the excitation efficiency by the light in the blue region is improved, the phosphor that is the main component of the light emitting composition 38 has excellent light emission characteristics that cannot be achieved by itself. It becomes possible.

  FIG. 2 is a cross-sectional view illustrating the configuration of a light source device and a display device using the same in an embodiment of the present invention.

  The display device 1 in the present embodiment includes a liquid crystal device as the optical device 3, and the light source device 2 for the liquid crystal device is a backlight device.

  As shown in FIG. 2, a large number of phosphor particles are dispersed on the surface of the light source 7 so as to cover, for example, a blue light source by a blue LED in the light guide unit 7 constituted by the transparent resin of the light source device 2. A white LED configured by applying a transparent resin, for example, a surface-emitting white LED as described with reference to FIG.

  As the resin constituting the light guide unit 7, various transparent resins can be used in addition to epoxy, silicone, and urethane. Further, the shape of the blue light source constituting the light emitter 6 can be appropriately selected from various types such as a side light emission type (side emitter type) and a shell type.

  A diffusion sheet 9 is provided at the closest portion of the light source device 2 facing the optical device 3. The diffusion sheet 9 uniformly guides the emitted light of the blue light source and the fluorescence from each phosphor excited by the emitted light to the optical device 3 side in a planar shape. A reflector 4 is provided on the rear surface side of the light source device 2, and a reflector 5 similar to the reflector 4 is also provided on the side surface of the light guide unit 7 as necessary.

  The optical device 3 is a liquid crystal device that outputs predetermined output light by modulating light emitted from the light source device 2. In this optical device 3, from the side close to the light source device 2, a deflection plate 10, a glass substrate 11 for TFT (Thin Film Transistor), a dot electrode 12 formed on the surface thereof, a liquid crystal layer 13 and An alignment film 14 deposited on the front and back surfaces, an electrode 15, a plurality of black matrices 16 formed on the electrodes 15, and a first color filter (red filter) corresponding to the pixels provided between the black matrices 16 ) 17a, the second color filter (green filter) 17b, the third color filter (blue filter) 17c, the glass substrate 18 provided apart from the black matrix 16 and the color filters 17a to 17c, and the deflection plate 19, Arranged in this order.

  The deflecting plates 10 and 19 are for forming light that vibrates in a specific direction. The TFT glass substrate 11, the dot electrode 12, and the electrode 15 are provided for switching the liquid crystal layer 13 that transmits only light vibrating in a specific direction, and the alignment film 14 is provided together. The inclination of the liquid crystal molecules in the liquid crystal layer 13 is aligned in a certain direction. The black matrix 16 improves the contrast of light output from the color filters 17a to 17c corresponding to the respective colors. The black matrix 16 and the color filters 17a to 17c are attached to the glass substrate 18.

Among the phosphors constituting the phosphor 6, an alkaline earth silicate phosphor is used as a green phosphor (blue-green phosphor or green phosphor) that is excited by light in the blue region and emits fluorescence in the green region, A glass layer containing silicon (Si) and oxygen (O) is formed on the surface of the alkaline earth silicate phosphor. Examples of the green phosphor excited by light in the blue region, as described in FIG. 1, Sr Mg salt is added _{x Ba 2-x SiO 4:} Eu ( where is 0 ≦ x ≦ 2 Etc.). In addition, as the first phosphor (green phosphor), SrGa ₂ S ₄ : Eu, SrSi ₂ N ₂ O ₂ : Eu, Eu activated β sialon-based green phosphor, Yb activated α sialon phosphor, Ca ₃ Sc ₂ SiO ₃ O ₁₂ : Ce, Y ₃ (Al, Ga) ₅ O ₁₂ : Ce, and the like can also be used.

Among the phosphors constituting the light emitter 6, examples of the red phosphor that is excited by the light in the blue region and emits the fluorescence in the red region include the nitride phosphor CaAlSiN ₃ : Eu as described in FIG. Is mentioned. In addition, as the second phosphor (red phosphor), (Ca, Sr) S: Eu, Ca ₂ Si ₅ N ₈ : Eu, K ₂ SiF ₆ : Mn, K ₂ GeF ₆ : Mn, K ₂ TiF ₆ : Mn, CaAl ₁₂ O ₁₉ : Mn, CaSiN ₂ : Eu, SrCaAlSiN ₃ : Eu, Eu complexes having a β-diketone ligand, and the like can also be used.

In addition to Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2) to which Mg salt is added as a green phosphor, silicate phosphor (Eu activation (Ba, Sr) , Ca, Mg) ₂ SiO ₄ phosphor) can also be used. In addition to CaAlSiN ₃ : Eu, a sulfide phosphor or the like can be used as the red phosphor, and the glass layer 22 may be formed on the surface of the red phosphor.

  As in the present embodiment, when the light source device 2 is configured inside the display device 1 or the like, the drive circuit of the light source device 2 is simplified by avoiding a configuration in which all colors are obtained by a direct drive light source such as an LED. It is possible to suppress deterioration of peripheral members (resin, LED chip, etc.) due to near ultraviolet light to ultraviolet light by avoiding the configuration using near ultraviolet light to ultraviolet light as excitation light, etc. In addition, the optical characteristics of the light source device 2 can be improved by the luminescent composition 38 having excellent luminescent characteristics.

  In the light source device 2 having the above-described configuration, the blue region light emitted from the blue light source, the green region fluorescence emitted by the green phosphor being excited by the blue region light, and the red fluorescence by the blue region light. The white chromaticity emitted from the light source device 2 as a whole is defined by the mixture of the fluorescent light in the red region that emits light when the body is excited, and light corresponding to the target color can be output.

  In the light source device 2 and the display device 1 of the present embodiment, since the surface of the green phosphor particles is covered with the glass layer, the reaction between the green phosphor and moisture in the atmosphere can be delayed, and the green phosphor It is possible to improve the moisture resistance by suppressing the characteristic deterioration due to the humidity of the liquid crystal display, and to realize a highly reliable display device that can perform stable display using the white LED as the backlight of the liquid crystal device 3.

  FIG. 3 is a diagram showing a process for producing a luminescent composition in the embodiment of the present invention.

  The manufacturing process of the luminescent composition shown in FIG. 3 includes a phosphor adjusting process, an additive adding process to the phosphor, and a glass layer forming process on the surface of the phosphor to which the additive has been added.

The outline of the phosphor adjustment process is as follows. As raw materials of strontium (Sr), barium (Ba), and europium (Eu) constituting the target phosphor, Sr source compound, Ba source compound, Si source compound, and Eu source compound are used. As the Sr source compound and Ba source compound, for example, oxides, hydroxides, chlorides, carbonates, sulfates, sulfides, nitrates and the like can be used. As the Si source compound, for example, SiO ₂ , H ₄ SiO ₄ , Si (OCOCH ₃ ) or the like can be used. As the Eu source compound, for example, oxides, chlorides, sulfates, sulfides and the like can be used.

_{Sr x Ba 2-x SiO 4} : Eu (. Proviso that 0 ≦ x ≦ 2) the raw materials were weighed to be the composition of a given stoichiometric ratio represented by, Sr source compound, Ba source compound, Eu source The compounds are mixed sequentially (Step S1).

  The mixture prepared in step S1 is wet-stirred and mixed by a rotating ball mill process or the like in an organic solvent such as alcohol (step S2).

  The wet-stirred mixture in step S2 is filtered to dry the filtration residue, and then ground using a mortar or the like to prepare an intermediate (step S3).

The intermediate body prepared in step S2 is placed in a quartz tube, and a predetermined gas is allowed to flow through the quartz tube, followed by firing treatment at a temperature in a predetermined temperature range (step S4), and a phosphor having a desired composition Sr _x Ba _2−x SiO ₄ : Eu (however, 0 ≦ x ≦ 2) can be adjusted.

  Next, a predetermined additive is added to the phosphor obtained in the above adjustment step (step S5). In this addition step, for example, magnesium (Mg) salt, barium (Ba) salt or the like is added as an additive and mixed using a ball mill, a mortar, or the like. As the Mg salt and Ba salt, for example, chloride, carbonate, sulfate, and fluoride are used.

In the present embodiment, the phosphor was adjusted as follows. In step 1, strontium carbonate (SrCO ₃ ) and barium carbonate (BaCO ₃ ) are used as the Ba source compound and the Sr source compound, respectively, europium oxide (Eu ₂ O ₃ ) as the Eu source compound, and silicon dioxide as the Si source compound. (SiO ₂ ) was used. The Eu source compound was added so as to be 1 mol% to 9 mol%.

  Note that the finally obtained light emitting composition had particularly good characteristics (light emission intensity) of the finally obtained light emitting composition when the Eu concentration was 2 mol% to 5 mol%. This is considered to be due to the fact that Eu acts as a light emission center in the phosphor, so that if the amount is too small, the emission intensity decreases, and if too large, the emission intensity decreases due to a phenomenon of concentration quenching.

  In step S2, 20 g of the mixture prepared in step S1 was transferred to a 500 mL plastic container, 200 mL of ethanol and 100 g of 5 mmφ alumina balls were added, and a rotating ball mill treatment (stirring) was performed for 3 hours.

  In step S3, the processed product of the rotating ball mill was filtered, and the filtration residue serving as the final sample precursor was dried in an air atmosphere at 50 ° C. for 2 hours, and then pulverized in an alumina mortar to obtain an intermediate. .

  In step S4, this intermediate is placed in a quartz tube, nitrogen gas containing 4% hydrogen gas is flowed into the quartz tube at a flow rate of 10 to 1000 mL / min, and is fired at 1000 ° C. to 1400 ° C. Thus, a phosphor that is a main component of the finally obtained light emitting composition was prepared. Note that the necessary flow rates of nitrogen gas and hydrogen gas vary depending on the amount of the intermediate to be fired. For example, if the firing amount is about several g, about 500 mL / min is considered sufficient, but firing is performed reliably. Therefore, a larger amount may be flowed. The optimum baking temperature was 1200 ° C.

  In step S5, a predetermined additive (Mg salt) was added to the phosphor prepared in steps 1 to 4.

  Next, a light emitting composition according to the present embodiment was produced by forming a glass layer on the surface by Step 6 to Step 9 described below.

A glass layer is formed on the surface of the phosphor Sr _x Ba _2-x SiO ₄ : Eu (where 0 ≦ x ≦ 2) in which the additive is added and mixed. It is formed by applying a sol-gel method to the added and mixed phosphor.

  The sol-gel method is capable of synthesizing glass at a relatively low temperature, and synthesizes glass using hydrolysis and dehydration condensation reactions starting from metal alkoxides with water and organic solvents added as necessary. is there.

In the present embodiment, as shown in FIG. 3, first, 2 g of the phosphor added and mixed with the additive is dispersed in 50 mL of ethanol and heated to 70 ° C. (step S6). Subsequently, 1 to 100 mL of tetraethoxysilane (TEOS; Si (OC ₂ H ₅ ) ₄ ) is added and stirred (step S7). Thereafter, 1 to 40 mL of H ₂ O for hydrolysis is added and stirred, and then heated and stirred for 2 hours (step S8). Next, the residue obtained by filtering the heated and stirred mixture is dried at 50 ° C. to 200 ° C. for 1 h to 48 h (step S9).

As described above, a luminescent composition having a phosphor to which an additive is added and a glass layer formed on the surface can be obtained. The coating state (amount and thickness of the coating) of this glass layer is adjusted as appropriate according to the amount of TEOS. The glass layer has a ratio of adding H ₂ O by 4 times the number of moles of TEOS. It is considered optimal to add H ₂ O corresponding to the above.

  In the above description, relatively inexpensive TEOS was used. However, other Si-based organometallic compounds can be used as the raw material, and as long as the glass layer can be formed as a continuous film, the raw material is It can be selected as appropriate. In the above description, no acid or alkali is added as a catalyst in the sol-gel method, but a necessary acid or alkali (hydrochloric acid, ammonia, etc.) can be added depending on the type of phosphor.

<Example>
Below, the Example regarding the light emitting composition which concerns on this invention, and the white LED which combined this light emitting composition with blue LED is demonstrated, the composition of the light emitting composition containing fluorescent substance, a light emitting composition, and this The light emission characteristic and moisture resistance regarding the used white LED will be described.

  Conventionally, it is considered that the moisture resistance of oxide phosphors and nitride phosphors is superior to that of sulfide phosphors. However, in the present invention, there is a difference in moisture resistance of individual phosphors. Therefore, prior to the construction of a white LED (light source device) composed of a combination of a luminescent composition and a blue LED, a reliability test on the moisture resistance of a luminescent composition containing a phosphor was conducted.

As a light emitting composition to be combined with a blue LED, a first light emitting composition containing a green phosphor and a second light emitting composition comprising a single red phosphor are used, and a silicate phosphor and a red color are used as a green phosphor. A nitride phosphor was used as the phosphor, and a reliability test on the moisture resistance of the first and second light-emitting compositions was performed. By using Sr _x Ba _2−x SiO ₄ : Eu (provided that 0 ≦ x ≦ 2) as the silicate phosphor, Mg salt is added thereto, and a glass layer is formed on the surface. A first luminescent composition was constructed. CaAlSiN ₃ : Eu was used as the nitride phosphor.

  First, the measurement of the fluorescence spectrum excited from the luminescent composition containing the phosphor, the measurement of the emission spectrum of the emitted light of the light source device, and the moisture resistance test of the luminescent composition and the white LED will be described.

  (1) Measurement of the photoluminescence spectrum (fluorescence spectrum) of the luminescent composition.

  The fluorescence spectrum was measured using a fluorescence spectrometer (FluoroLog-3 (FL3-22 System, Software: Data Max) of Instruments SA, Inc. A xenon lamp was used as an excitation light source. Sample for measuring fluorescence spectrum Luminescent composition particles having a phosphor with a glass layer formed in an opening (having a diameter of 1 cm and a depth of 0.5 mm) of the holder, or a luminescent composition having a phosphor with no glass layer formed The particles are packed so as to form a flat surface, the sample holder is set in the fluorescence spectrometer, the excitation light of 450 nm is irradiated on the surface of the opening of the sample holder, and the fluorescence emitted from the surface of the opening Was detected by a photoreceiver.

  (2) A moisture resistance test of the luminescent composition.

  A sample holder for measuring a fluorescence spectrum filled with luminescent composition particles is set in a small environmental tester (model SH-641) manufactured by Espec Co., Ltd. at 60 ° C. (or 85 ° C.), 90% In the RH atmosphere, an accelerated test for humidification deterioration was performed. After a lapse of a predetermined time, the sample holder was taken out from the small environmental tester, and changes in the fluorescence spectrum and emission intensity were measured.

  (3) Measurement of emission spectrum and luminance of white LED (light source device).

  A blue LED chip mounted on a circuit board is covered with a transparent resin (silicone resin) in which a light emitting composition containing a red phosphor and a light emitting composition containing a green phosphor are dispersed, and a white LED mounted on the circuit board The white LED mounted on the circuit board is set in an integrating sphere, and the variable resistance on the circuit board is adjusted so that a current of 20 mA flows through the blue LED. Measurement and emission luminance measurement were performed.

  (4) Moisture resistance test of white LED.

  The white LED mounted on the above-mentioned circuit board is set in the above-mentioned small environmental tester (model SH-641) of espec, including the circuit board, and in an atmosphere of 60 ° C. and 90% RH. Then, an accelerated test for humidification deterioration was performed. After a certain period of time, the white LED mounted on the circuit board including the circuit board is taken out from the small environmental tester and set in the integrating sphere so that a current of 20 mA flows through the blue LED. The variable resistance was adjusted to measure the emission spectrum and the emission luminance.

In the first embodiment and below, the composition of a luminescent composition containing a phosphor will be described. In addition, the glass layer is not formed in the light emitting composition in a present Example.

In this example, a phosphor having a predetermined stoichiometric ratio within the composition range represented by Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2), and the phosphor The light-emitting composition having an Mg salt as an additive to be added was examined by measuring an excitation spectrum (described later).

  Then, the value of (excitation intensity at an excitation wavelength of 450 nm) / (excitation intensity at an excitation excitation wavelength of 370 nm) relating to this excitation spectrum is detected, and the luminescent composition of the excitation intensity at the excitation wavelength of 450 nm relating to this excitation spectrum is obtained. Comparison was made with respect to excitation intensity at an excitation wavelength of 450 nm of a single phosphor having the same stoichiometric ratio as that of the constituting phosphor.

  The excitation spectrum (PLE) is irradiated with monochromatic excitation light with a wavelength shift from 300 nm to 500 nm using FluoroLog-3 (FL3-22 System, Software: Data Max) of Instruments SA, Inc. The emission spectrum intensity at the maximum emission peak position of the emission spectrum was measured and obtained (for example, see FIG. 5 described later).

  In the study in this example, as an additive constituting the luminescent composition, barium chloride, barium carbonate, barium sulfate, barium fluoride, calcium chloride, calcium carbonate, calcium sulfate, calcium fluoride, magnesium chloride, magnesium carbonate, sulfuric acid Magnesium, magnesium fluoride, ammonium chloride, potassium chloride, oxalic acid, potassium phosphate, boric acid, aluminum chloride, aluminum carbonate, aluminum sulfate, and aluminum fluoride were used.

  The production of the light-emitting composition according to this example is specifically performed by adding each additive in a range of 1 mol to 30 mol with respect to 100 mol of the phosphor and mixing with a ball mill or a mortar. A luminescent composition was prepared.

  The amount of each additive added was confirmed by energy dispersive X-ray fluorescence analysis (EDX), inductively coupled plasma emission analysis (ICP), and the like.

FIG. 4 shows SrBaSiO ₄ : Eu (additional additive is a constant concentration) with x = 1.0 in Sr _x Ba _2−x SiO ₄ : Eu in the first embodiment of the present invention. (3 mol%))) A diagram showing the relationship between the amount of additive added and the excitation intensity of the excitation spectrum of the luminescent composition in the luminescent composition having a phosphor (without a glass layer), that is, SrBaSiO ₄ : It is a figure which shows the relationship between the quantity of the additive added to Eu fluorescent substance, and the relative light emission intensity when excited by the light of 450 nm, and is the chloride in which the highest light emission characteristic was acquired among the additives added The addition amount of an additive (magnesium chloride) and the measurement result of relative luminescence intensity regarding the luminescent composition containing magnesium are shown.

  In FIG. 4, the horizontal axis indicates the amount added (mol), the vertical axis indicates the emission spectrum intensity at the maximum emission peak position of the emission spectrum when excited by light of 450 nm, and fluorescence without adding Mg salt. The relative luminescence intensity of the luminescent composition containing the additive is shown with the luminescence intensity of the single body as 100.

  Even in a composition having a phosphor to which any of magnesium-based additives including Mg salt is added, when the addition amount is 3 mol to 15 mol with respect to 100 mol of the phosphor, the addition amount is at least 1 mol and 30 mol or less. It has been confirmed that it is more suitable than the case, and particularly when the additive is magnesium chloride, good light emission characteristics can be obtained. For example, when magnesium chloride is used as the additive, As shown in FIG. 4, when the addition amount of magnesium chloride is 1 mol or more and 30 mol or less with respect to 100 mol of the phosphor, it is twice or more as compared with the case where the phosphor alone without adding the Mg salt is used as the light emitting composition. It was also revealed that the emission intensity was shown.

FIG. 5 and FIG. 6 show the light emitting composition having a single phosphor (no glass layer) and the light emitting composition having a phosphor added with magnesium chloride (no glass layer) in the first embodiment of the present invention. is a diagram showing the excitation spectrum, fluorescent SrBaSiO _4: Eu (Eu concentration was 3 mol%.) single excitation spectrum, and the phosphor SrBaSiO ₄ that magnesium chloride is added: Eu (Eu concentration and 3 mol% Excitation spectrum (shown in a smooth curve traced from the measured spectrum).

  5 and 6, the horizontal axis indicates the excitation wavelength (nm). The vertical axis of FIG. 5 shows the relative excitation intensity of each luminescent composition normalized so that the maximum value of the peak around 340 nm of the excitation spectrum of YAG: Ce (shown by curve g) is 1. ing. FIG. 6 does not show the excitation spectrum of YAG: Ce in FIG. 5, and shows the relative excitation intensity of each luminescent composition by normalizing the peak value of the excitation spectrum of each luminescent composition to be 1. Yes.

5 and 6, curves a, b, c, d, e, and f are obtained by adding 0, 1, 5, 10, 15, and 30 mol of magnesium chloride to SrBaSiO ₄ : Eu, which is the base material, respectively. The excitation spectrum of the obtained luminescent composition is shown.

From the results shown in FIG. 5, the excitation intensity at a wavelength of 450 nm of the excitation spectrum of SrBaSiO ₄ : Eu added with 1 to 30 mol of magnesium chloride is the intensity at the excitation wavelength of 450 nm of the excitation spectrum of SrBaSiO ₄ : Eu without addition. 1.53 times (about 1.5 times) or more and 1.86 times (about 1.9 times) or less.

The excitation intensity at a wavelength of 370 nm of the excitation spectrum of SrBaSiO ₄ : Eu added with 1 to 30 mol of magnesium chloride is 1.05 of the intensity at the excitation wavelength of 370 nm of the excitation spectrum of the additive-free SrBaSiO ₄ : Eu alone. Times (about 1.1 times) or more and 1.40 times (about 1.4 times) or less.

Thus, from the results shown in FIG. 5, SrBaSiO ₄ : Eu to which 1 to 30 mol of magnesium chloride was added had a higher excitation efficiency than that of YAG: Ce and no added SrBaSiO ₄ : Eu alone, and no added SrBaSiO _4. : It is clear that the improvement of the excitation efficiency at 450 nm is larger than the improvement of the excitation efficiency at 370 nm compared to Eu alone, and magnesium chloride is added to the SrBaSiO ₄ : Eu phosphor. Thus, a light emitting composition having excellent light emitting characteristics can be obtained.

From the results shown in FIG. 6, the value of (intensity at an excitation wavelength of 450 nm) / (intensity at an excitation wavelength of 370 nm) regarding an additive-free SrBaSiO ₄ : Eu simple substance is 0.53, whereas magnesium chloride is 1 mol. The value of (intensity at an excitation wavelength of 450 nm) / (intensity at an excitation wavelength of 370 nm) with respect to the excitation spectrum of SrBaSiO ₄ : Eu to which 30 mol is added is 0.67 or more and 0.83 or less.

Thus, SrBaSiO ₄ magnesium chloride were added: Eu is additive-free SrBaSiO _4: It is clear that the excitation efficiency at the excitation wavelength of 450nm than Eu phosphor itself is improved, SrBaSiO _4: Eu By adding magnesium chloride to the phosphor, a light emitting composition having excellent light emission characteristics can be obtained.

Measurement of the excitation spectrum of the luminescent composition is carried out by measuring x = 0, 1, in a composition represented by Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2) contained in the luminescent composition. However, since the same tendency was shown, FIGS. 5 and 6 show an example where x = 1, that is, SrBaSiO ₄ : Eu (Eu concentration was 3 mol%). Shows the results with the phosphor composition.

Although not shown in the drawing, the excitation intensity of the luminescent composition in which the concentration of Mg added to the Sr _x Ba _2−x SiO ₄ : Eu phosphor alone in which x (where 0 ≦ x ≦ 2) is changed is changed. Has been confirmed to be about 1.5 times or more and about 2.1 times or less the intensity at an excitation wavelength of 450 nm of the excitation spectrum of a phosphor alone without adding Mg.

As shown in FIG. 5 and FIG. 6, the spectrum of the luminescent composition containing magnesium chloride as an example of the luminescent composition according to this example compared to the spectrum of the phosphor SrBaSiO ₄ : Eu alone (curve a). In (curves b, c, d, e, f), the excitation intensity is greatly improved by the addition of magnesium chloride, and the shape of the excitation spectrum changes depending on whether or not magnesium chloride is added, and the excitation wavelength is 370 nm. It is shown that excellent excitation characteristics are obtained in which both the excitation efficiency of the phosphor and the excitation efficiency at an excitation wavelength of 450 nm are improved as compared with the phosphor alone.

  The same tendency shown in FIGS. 5 and 6 was the same for other Mg salts (magnesium carbonate, magnesium sulfate, magnesium fluoride).

In the light emitting composition having the phosphor to which the Mg salt is added, excellent light emission characteristics are obtained by adding the Mg salt to Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ This is probably because the band structure of the phosphor having the composition represented by (2) is changed.

When a sample of Sr ₁ Ba ₁ SiO ₄ (Eu 3%) added with ₁₀ mol% of Mg was subjected to ICP analysis, Sr-0.969, Ba-0.926, Si-1, Eu-0.059, Mg-0.045 The value was detected at such a ratio. Sr, Ba, Si, and Eu were almost as charged, but it was found that Mg was taken in (entered) into the product (light emitting composition) only about half of the charged amount. Moreover, the peak of Mg oxide was not detected from the result of the XRD (X-ray diffraction) θ-2θ measurement.

  The above is the result when magnesium chloride is added to the phosphor matrix. However, even when magnesium chloride is added to the phosphor matrix, the possibility that magnesium oxide is precipitated by the baking treatment after the addition is sufficiently considered. However, since magnesium oxide was not detected as a result of XRD, it is considered that magnesium was taken into the matrix.

  In addition to the fact that Mg was detected by ICP analysis of the luminescent composition and the peak of Mg oxide was not detected by X-ray diffraction, as shown in FIG. 5 and FIG. (PLE) changes, and as will be described later (see FIG. 7), in the sample to which 30 mol% of Mg is added, the emission peak is shifted to the longer wavelength side. It can be considered that the band structure of the matrix is changed due to incorporation into (inclusion), and that the property of light emission has changed greatly. It is conceivable that Mg is in the group 2 site of the phosphor (matrix).

FIG. 7 shows emission spectra of a light emitting composition having a single phosphor (no glass layer) and a light emitting composition having a phosphor added with magnesium chloride (no glass layer) in the first embodiment of the present invention. The curve a is an emission spectrum of the phosphor SrBaSiO: Eu (Eu concentration is 3 mol%), and the curve b is SrBaSiO ₄ : Eu to which 10 mol of magnesium chloride is added (Eu concentration is 3 mol%). )), The curve c shows the emission spectrum of SrBaSiO ₄ : Eu (Eu concentration was 3 mol%) to which 10 mol of magnesium chloride was added, and the curve d shows the emission spectrum of YAG: Ce.

  In FIG. 7, the horizontal axis indicates the emission wavelength (nm), and the vertical axis indicates the relative emission intensity of each luminescent composition, normalized so that the maximum emission peak intensity of YAG: Ce is 1.

The emission spectrum is measured for three cases of x = 0, 0.5 and 2 in the composition represented by Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2). However, since the same tendency was shown, FIG. 7 shows the result when x = 1.0 as an example.

In FIG. 7, the dotted lines shown vertically indicate the maximum positions of curves a, b, and c, about 515 nm, about 517 n, and about 523 m, respectively. The emission peak position of the emission spectrum (curve c) of the luminescent composition containing 30% magnesium chloride is clearly longer than the emission peak position of the emission spectrum (curve a) of SrBaSiO ₄ : Eu not containing magnesium chloride. Shifted to the wavelength side. This is considered that the band structure of the host (SrBaSiO ₄ : Eu) has changed due to Mg being taken in (entered) in consideration of the results of the above-described ICP analysis and X-ray diffraction.

As shown in FIG. 7, when the maximum emission peak intensity of the emission spectrum of YAG: Ce (curve d) is 1.00, the maximum emission of the emission spectrum (curve a) of the additive-free SrBaSiO ₄ : Eu phosphor alone. The peak intensity is 0.83 (about 0.8), and the maximum emission peak intensity of the emission spectrum (curve b, curve c) of SrBaSiO ₄ : Eu added with 10 mol and 30 mol of magnesium chloride is 1.68 (about 1.7) and 2.00, and the emission spectrum intensity of SrBaSiO ₄ : Eu to which magnesium chloride is added is larger than the emission spectrum intensity of YAG: Ce.

When the maximum emission peak intensity of the emission spectrum (curve a) of the SrBaSiO ₄ : Eu phosphor alone without addition is 1.00, the maximum emission spectrum of SrBaSiO ₄ : Eu added with 10 mol and 30 mol of magnesium chloride, respectively. The intensity is 2.03 (about 2.0), 2.42 (about 2.4).

An emission spectrum of a single phosphor having a composition represented by SrBaSiO ₄ : Eu (shown by a curve a in FIG. 7) is an emission spectrum of a YAG: Ce phosphor generally used in a light source device capable of emitting white light. (Indicated by the curve d in FIG. 7) The emission intensity is lower than that of the phosphor (having a composition represented by SrBaSiO ₄ : Eu), but 10 mol and 30 mol of Mg salt with respect to 100 mol. The emission spectrum (shown by curves b and c in FIG. 7) of the luminescent composition to which was added showed higher emission intensity than the YAG: Ce phosphor, and it was confirmed that the emission characteristics were excellent. This tendency was the same in other Mg salts (magnesium carbonate, magnesium sulfate, magnesium fluoride).

Second Example In the present example, the characteristics of the luminescent composition were examined in a form closer to the configuration of the light source device described above. In addition, the glass layer is not formed in the light emitting composition in a present Example.
In this embodiment, the phosphor is composed of a phosphor having a composition represented by Sr _x Ba _2-x SiO ₄ : Eu (where 0 ≦ x ≦ 2) and 10 mol of Mg salt added thereto. The light emitting composition was mixed with a transparent resin, and this mixture was potted on a blue LED to evaluate the light emission characteristics.

In this example, a phosphor Sr ₂ SiO ₄ : Eu (Eu concentration was 3 mol%) with x = 2 in Sr _x Ba _2−x SiO ₄ : Eu was prepared and adjusted. On the other hand, the difference in luminous intensity with and without magnesium chloride was investigated. Here, the luminous intensity is a light intensity per unit solid angle of light emitted from a point light source as light intensity. As a result of the examination, it was confirmed that the luminous intensity when 10 mol of magnesium chloride was added to 100 mol of the phosphor was improved by 32% compared to the luminous intensity when not added.

In addition, the emission center wavelength is Sr _x Ba _2−x SiO ₄ : Eu (where x = 1, and the Eu concentration is 3 mol%), compared with a green phosphor having a composition represented by: As a second phosphor existing on the long wavelength side, a red phosphor having a composition represented by CaS: Eu (Eu concentration is 0.4 mol%) that can be excited by excitation light in a blue region (peak wavelength) 658 nm), these two phosphors were mixed (the green phosphor and the red phosphor were mixed at a weight ratio of 97: 3), and then a magnesium-based additive was added (the above green phosphor). 10 mol of magnesium chloride was added to 100 mol of the phosphor.) When the light emission characteristics were examined, it was confirmed that a color temperature of 3000 K was obtained. In addition, it is thought that the light source device which can obtain the color temperature of 3000K or less can also be comprised by increasing the mixing ratio of the said red fluorescent substance.

Third Example In this example, first, Sr _x Ba _2-x SiO ₄ : Eu (where 0 ≦ x ≦ 2) to which an Mg salt (magnesium chloride) was added, phosphor alone, and As a result of the reliability test on the moisture resistance of the CaAlSiN ₃ : Eu phosphor alone, Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2) added with Mg salt (magnesium chloride). The reliability test results regarding the moisture resistance of the white LED in which the simple substance and the CaAlSiN ₃ : Eu simple substance are combined with the blue LED will be described, and then Sr _x Ba _2-x SiO to which Mg salt (magnesium chloride) is added ₄ : Eu (provided that 0 ≦ x ≦ 2) a luminescent composition in which a glass layer is formed on the surface of the phosphor, the emission spectrum of the luminescent composition, the presence or absence of the glass layer in the luminescent composition, and Moisture resistance reliability Test results will be described the light emitting composition Reliability test results for the moisture resistance of the white LED in combination with a blue LED.

FIG. 8 shows Sr _x Ba _2−x SiO ₄ : Eu to which Mg salt (magnesium chloride 10 mol) is added in the third embodiment of the present invention (where x = 1 and Eu concentration is 3 mol%). ) Phosphor (without glass layer) alone and CaAlSiN ₃ : Eu (Eu concentration was 3 mol%). It is a figure explaining the time-dependent change of the emitted light intensity of fluorescent substance.

FIG. 8A is a diagram showing the reliability test results of a single SrBaSiO ₄ : Eu phosphor added with an Mg salt at 60 ° C. and 90% RH, and FIG. 3B is a graph showing 60 ° C. and 90% RH. it is a diagram illustrating a reliability test result of Eu: CaAlSiN ₃ in.

  In FIG. 8, the horizontal axis represents the elapsed time when the phosphor was exposed to 60 ° C. and 90% RH atmosphere, and the vertical axis represents the light emission before the phosphor was exposed to 60 ° C. and 90% RH atmosphere. When the intensity is 100, the light emission intensity after the above-mentioned elapsed time is shown, and the light emission intensity maintenance rate (%) is shown.

As shown in FIG. 8 (A), the emission intensity of the SrBaSiO ₄ : Eu phosphor to which the Mg salt is added decreases by about 20% after about 500 hours. As shown in FIG. 8B, CaAlSiN ₃ : Eu does not show a decrease in emission intensity even after about 500 hours.

As described above, the nitride phosphor CaAlSiN ₃ : Eu has high moisture resistance. On the other hand, it is a silicate phosphor, and Sr _x Ba _2−x SiO ₄ : Eu to which Mg salt is added (however, And 0 ≦ x ≦ 2.) It was revealed that the moisture resistance was low.

Next, Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2) phosphor added with Mg salt and CaAlSiN ₃ : Eu phosphor alone are combined with a blue LED. The LED reliability test result will be described.

FIG. 9 shows Sr _x Ba _2−x SiO ₄ : Eu to which Mg salt (magnesium chloride 10 mol) is added in the third embodiment of the present invention (where x = 1 and Eu concentration is 3 mol%). ) Phosphor (without glass layer) alone (first light emitting composition) and CaAlSiN ₃ : Eu (Eu concentration was 3 mol%) Phosphor (without glass layer) alone (second light emitting composition) Is a figure explaining the reliability test result regarding the moisture resistance of the white LED combined with the blue LED, and is a figure explaining the time-dependent change of the characteristics of the white LED.

  The first light-emitting composition and the second light-emitting composition described above are mixed at a weight ratio of 95: 5 and dispersed in a transparent silicone resin KJR (Shin-Etsu Chemical Co., Ltd.), then potted on a blue LED, and white An LED was constructed.

  The solid line shown in FIG. 9A is a diagram showing the emission luminance maintenance rate of the white LED at 60 ° C. and 90% RH, and FIG. 9B is the initial emission spectrum of the white LED at 60 ° C. and 90% RH, It is a figure which shows the emission spectrum after 512-hour progress.

  In FIG. 9A, the horizontal axis represents the elapsed time when the white LED was exposed to 60 ° C. and 90% RH atmosphere, and the vertical axis represents the time before the white LED was exposed to 60 ° C. and 90% RH atmosphere. When the emission luminance is 100, the emission luminance after the elapsed time is shown, and the emission luminance maintenance ratio (%) is shown. Note that the dotted line shown in FIG. 9A shows the change over time of the emission intensity of the single phosphor shown in FIG. 8A, and the solid line and the dotted line show almost the same change over time.

  FIG. 9B shows the emission spectrum (initial spectrum) of the white LED before exposing the white LED in a 60 ° C., 90% RH atmosphere, and the white LED exposed in a 60 ° C., 90% RH atmosphere for 512 hours. The emission spectrum of the white LED after the exposure (the spectrum after exposure for 512 hours) is shown. In FIG. 9B, the horizontal axis indicates the emission wavelength (nm), the vertical axis indicates the relative emission intensity, and the intensity of the emission spectrum measured using an integrating sphere is shown as it is.

As shown in FIG. 9A, the light emission luminance of the white LED decreases by about 20% when 500 hours have elapsed. This decrease is considered to result from a decrease in the emission intensity of the SrBaSiO ₄ : Eu phosphor added with the Mg salt shown in FIG. 8 (A).

  As shown in FIG. 9B, the emission spectrum of the white LED after being exposed to a 90% RH atmosphere for 512 hours is from the green region to the red region, even though the emission spectrum of the blue region is the same. It is different from the initial spectrum. As a result, the chromaticity and color rendering properties of the emitted light from the white LED change.

As shown in FIG. 8B, the emission intensity of CaAlSiN ₃ : Eu after about 500 hours has not decreased, but as is clear from FIG. 9B, from the blue region to the red region. The emission intensity is lowered by exposure in a 60% 90% RH atmosphere for 512 hours. The peak emission intensities in the blue region and the red region are each reduced by about 20%.

In FIG. 9B, the decrease in the emission intensity in the blue region is considered to be due to the humidity deterioration of the SrBaSiO ₄ : Eu green phosphor added with the Mg salt, and the decrease in the emission intensity in the red region is the red phosphor. It is considered that the excitation band of CaAlSiN ₃ : Eu extends to the green wavelength band in addition to the blue color, and it is considered that the excitation of the red phosphor is lowered due to the deterioration of the green phosphor.

As is clear from FIG. 8 and FIG. 9, even when Sr _x Ba _2−x SiO ₄ : Eu phosphor alone added with Mg salt and CaAlSiN ₃ : Eu alone are used, the emission luminance and chromaticity are changed over time. A stable white LED cannot be realized. To ensure long-term reliability of the white LED, Sr Mg salt is added _x Ba _2-x SiO _4: It has been found Eu green phosphor must be a moisture for improved. In this example, a glass layer (film) was formed as a moisture-resistant coating on a green phosphor having poor moisture resistance and an Sr _x Ba _2-x SiO ₄ : Eu phosphor to which an Mg salt was added.

  In this example, the phosphor was adjusted by the procedure shown in FIG. 3 and an Mg salt was added. Next, a light emitting composition was prepared by forming a glass layer, and an electron microscope observation and a reliability test were performed. Further, a reliability test on the emission spectrum of the luminescent composition, the presence or absence of a glass layer in the luminescent composition and the moisture resistance is performed, and the reliability test on the moisture resistance of a white LED in combination with the luminescent composition is performed. Went.

In this example, a phosphor was prepared according to the procedure shown in FIG. 3, and an Mg salt (magnesium chloride 10 mol) was added thereto. 2 g of Sr _x Ba _2−x SiO ₄ : Eu phosphor to which Mg salt is added and mixed is dispersed in 50 mL of ethanol and heated to 70 ° C. (step S6). Subsequently, 30 mL of tetraethoxysilane (TEOS; Si (OC ₂ H ₅ ) ₄ ) is added and stirred (step S7). Thereafter, 9.6 mL of H ₂ O for hydrolysis is added and stirred, and then heated and stirred for 2 hours (step S8). Next, the residue obtained by filtering the heated and stirred mixture was dried at 50 ° C. to 200 ° C. for 1 h to 48 h (step S9). Thus, the light emitting composition in which the glass layer was formed on the surface was adjusted.

FIG. 10 shows Sr _x Ba _2−x SiO ₄ : Eu to which Mg salt (magnesium chloride 10 mol) is added in the third embodiment of the present invention (where x = 1 and Eu concentration is 3 mol%). FIG. 4 is an electron micrograph of a luminescent composition powder having a glass layer formed on the surface of a phosphor.

  10A is a scanning electron microscope (SEM) image of the luminescent composition powder, and FIG. 10B is a transmission electron microscope (TEM) image (cross-sectional photograph) of the cross section of the luminescent composition powder.

  As shown in FIG. 10 (B) which shows one cross-sectional image of the luminescent composition powder shown in FIG. 10 (A), the surface of the luminescent composition powder shown by the black portion above FIG. It can be seen that a thin film having a thickness of 80 nm is continuously formed almost uniformly. This thin film was a layer that was not observed by observation with a single phosphor, and was considered to be a glass layer containing silicon (Si) and oxygen (O) formed by the sol-gel method described above.

This thin film, EDX (energy dispersive X-ray spectroscopy) Composition analysis by, are detected Si element and O chlorine, and, since the elements such as Ba or Sr is not detected, the thin film is SiO _x (mainly It was confirmed that the glass layer was made of SiO ₂ . From the observation result of FIG. 10, it was confirmed that the glass layer was continuously coated on the surface of the phosphor particles to which the Mg salt was added. The glass coat covering the surface of the phosphor particles is composed of a continuous amorphous layer containing at least silicon (Si) and oxygen (O) and a deposit made of Si and O attached to this layer.

FIG. 11 shows Sr _x Ba _2−x SiO ₄ : Eu to which Mg salt (magnesium chloride 10 mol) is added in the third embodiment of the present invention (where x = 1 and Eu concentration is 3 mol%). FIG. 2 is a diagram illustrating a change in emission spectrum (PL spectrum) before and after the formation of a glass layer on a surface of a phosphor composition in which a glass layer is formed on the surface of a phosphor.

  In FIG. 11, the horizontal axis indicates the emission wavelength (nm), the vertical axis indicates the relative emission intensity, the emission spectrum before the formation of the glass layer, and the emission spectrum after the formation of the glass layer indicate the measured intensity as they are. Yes.

  As shown in FIG. 11, the shape of the emission spectrum (measured using the above-described fluorescence spectrometer (FluoroLog-3)) before and after forming the glass layer on the surface of the phosphor particles to which the Mg salt was added, The light emission intensity hardly changes. From this, it was confirmed that the glass layer formed on the surface hardly caused deterioration in characteristics such as emission intensity and chromaticity of the phosphor.

  Next, the phosphor (luminescent composition) in which the glass layer is formed on the surface of the phosphor particles to which the Mg salt is added in this example is subjected to a severe 85 condition under the conditions of 60 ° C. and 90% RH. A reliability test was conducted under the conditions of 90 ° C. and 90% RH.

FIG. 12 shows Sr _x Ba _2−x SiO ₄ : Eu to which Mg salt (magnesium chloride 10 mol) is added in the third embodiment of the present invention (where x = 1 and Eu concentration is 3 mol%). In the luminescent composition in which a glass layer is formed on the surface of the phosphor, it is a diagram showing the reliability test results regarding the presence or absence of the glass layer and moisture resistance, and the presence or absence of the glass layer and the emission intensity of the phosphor. It is a figure explaining a time-dependent change.

  FIG. 12A shows the emission intensity maintenance rate of the luminescent composition at 60 ° C. and 90% RH, and FIG. 12B shows the emission intensity maintenance rate of the luminescent composition at 85 ° C. and 90% RH. FIG.

  In FIG. 12, the horizontal axis represents the elapsed time when the luminescent composition was exposed to a warmed and humidified atmosphere, and the vertical axis represents the luminescence intensity before the luminescent composition was exposed to a warmed and humidified atmosphere as 100. The emission intensity after the elapsed time is shown, and the emission intensity maintenance rate (%) is shown.

  In FIG. 12 (A), (a) is the same as FIG. 8 (A), and shows the emission intensity maintenance rate (%) for the light emitting composition in which the glass layer is not formed on the surface, and (b) is FIG. 12 shows the emission intensity maintenance rate (%) related to the luminescent composition having the glass layer formed on the surface. In FIG. 12B, (a) shows the luminescent intensity related to the luminescent composition having no glass layer formed on the surface. The maintenance rate (%) is shown, and (b) shows the emission intensity maintenance rate (%) related to the luminescent composition having a glass layer formed on the surface.

  As shown in (a) and (b) of FIG. 12 (A), in a luminescent composition having a glass layer formed on the surface after about 500 hours after exposure in an atmosphere of 60 ° C. and 90% RH. Although the emission intensity is hardly reduced, the emission intensity is reduced by about 20% in the light emitting composition in which the glass layer is not formed on the surface.

  As shown in (a) and (b) of FIG. 12 (B), in a light emitting composition in which a glass layer is formed on the surface after about 500 hours after exposure in an atmosphere of 85 ° C. and 90% RH. The emission intensity is reduced by about 5%, but the emission intensity is reduced by about 25% in the light emitting composition in which the glass layer is not formed on the surface.

  From the results shown in FIG. 12, the light emitting composition in which the glass layer is formed on the surface improves the moisture resistance and the light emission intensity as compared with the case of the single phosphor not forming the glass layer on the surface of the light emitting composition. It was confirmed that it was maintained stably for a long time.

  Although not shown in FIG. 12, it is considered that the moisture resistance of other alkaline earth silicate phosphors is also improved by coating with a glass layer.

As such an alkaline earth silicate phosphor, CaSiO ₃ : (Eu, Ce, Pb, Ti, Mn), (Be, Mg, Zn, Ba, Sr) ₂ SiO ₄ : (Mn, P, As, Ti) , Li, Eu), BaSi ₂ O ₅ (Eu, Pb), Y ₂ SiO ₅ : Ce, CaMgSi ₂ O ₆ : Eu, Ca ₂ MgSi ₂ O ₇ , (Ca, Sr, Ba) ₂ MgSi ₂ O ₇ : _{(Eu, Mn), BaMg 2} Si 2 O 7: Eu, BaSrMgSi 2 O 7: Eu, Ba 2 Li 2 Si 2 O 7: (Sn, Mn), MgSrBa 2 Si 2 O 7: Eu, MgSr 3 Si 2 _{O 8: (Eu, Mn)} , Sr 3 MgSi 2 O 8: Eu, Ca 5 B 2 SiO 10: Eu, Ca 3 Al 2 Si 3 O 12: Eu, LiCeBa 4 Si 4 O 14: be exemplified such as Mn Can do.

Next, the light-emitting composition having a glass layer formed on the surface and the nitride phosphor (CaAlSiN ₃ : Eu (Eu concentration was 3 mol%)) used in the reliability test described in FIG. Using a dispersed silicone resin, a blue LED was potted to form a white LED, and a reliability test was performed under conditions of 60 ° C. and 90% RH.

FIG. 13 shows Sr _x Ba _2−x SiO ₄ : Eu to which Mg salt (magnesium chloride 10 mol) is added in the third embodiment of the present invention (where x = 1 and Eu concentration is 3 mol%). A light-emitting composition (first light-emitting composition) in which a glass layer is formed on the surface of the phosphor and CaAlSiN ₃ : Eu (Eu concentration is 3 mol%) phosphor (no glass layer) alone It is a figure explaining the reliability test result regarding the moisture resistance of white LED which combined (2nd light emitting composition) with blue LED, and is a figure explaining the time-dependent change of the characteristic of white LED.

  The first light-emitting composition and the second light-emitting composition described above are mixed at a weight ratio of 95: 5 and dispersed in a transparent silicone resin KJR632 (Shin-Etsu Chemical Co., Ltd.), and then potted on a blue LED to obtain a white color. An LED was constructed.

  FIG. 13A is a diagram showing the emission luminance maintenance ratio of the white LED at 60 ° C. and 90% RH, and FIG. 13B is the initial emission spectrum of the white LED at 60 ° C. and 90% RH, after 530 hours. It is a figure which shows the later light emission spectrum.

  In FIG. 13A, the horizontal axis represents the elapsed time when the white LED was exposed to an atmosphere of 60 ° C. and 90% RH, and the vertical axis represents the time before the white LED was exposed to an atmosphere of 60 ° C. and 90% RH. When the emission luminance is 100, the emission luminance after the elapsed time is shown, and the emission luminance maintenance ratio (%) is shown.

  As shown in FIG. 13 (A), no reduction in light emission luminance is observed even after the white LED is exposed to an atmosphere of 60 ° C. and 90% RH for 500 hours.

  FIG. 13B shows the emission spectrum (initial spectrum) of the white LED before exposing the white LED in a 60 ° C., 90% RH atmosphere, and the white LED exposed in a 60 ° C., 90% RH atmosphere for 512 hours. 2 shows the emission spectrum of the white LED after being made, the horizontal axis shows the emission wavelength (nm), the vertical axis shows the relative emission intensity, and shows the intensity of the emission spectrum measured using an integrating sphere as it is.

  As shown in FIG. 13B, the emission spectrum shows almost the same spectrum as the initial spectrum even after 530 hours after the white LED was exposed to 60 ° C. and 90% RH atmosphere.

As shown in FIG. 9B, the emission spectrum of a white LED in which a Mg salt is added and a SrBaSiO ₄ : Eu phosphor (without a glass layer) alone and a CaAlSiN ₃ : Eu phosphor alone are combined with a blue LED. However, as shown in FIG. 13B, a glass layer was formed on the surface of the SrBaSiO ₄ : Eu phosphor to which the Mg salt was added. In the emission spectrum of the white LED in which the luminescent composition is combined with the blue LED, the emission characteristics in the green region and the red region are not deteriorated, and the emission properties are not deteriorated at all.

This is considered to be because the green phosphor that excites the excitation band in the green region of the nitride phosphor (CaAlSiN ₃ : Eu) was not deteriorated, and the green phosphor (Sr _x Ba _2-x ) to which Mg salt was added. SiO ₄ : Eu) By using a light-emitting composition constituted by forming a glass layer on the surface of a phosphor, the humidity resistance of only the green phosphor is improved, so that only the green region of the white LED emits light. In addition, the characteristics of the red region can be improved.

As described above, after adding an Mg salt to a green phosphor having a composition represented by Sr _x Ba _2-x SiO ₄ : Eu (where 0 ≦ x ≦ 2), By forming a light emitting device (white LED) by combining a luminescent composition formed by forming a glass layer on a blue LED, or by configuring a display device or the like having this light source device, these The device (apparatus) can be provided with a reliability sufficient to withstand a high temperature and high humidity reliability test.

  As described above, the embodiments and examples of the light-emitting composition and the light source device according to the present invention have been described. However, the materials used in the description of this embodiment and the numerical conditions such as the amount, processing time, and weight are preferable. It is only an example and the dimensional shape and arrangement | positioning relationship in each figure used for description are also approximate. That is, the present invention is not limited to this embodiment.

For example, the light source device according to the present embodiment has a composition represented by Sr _x Ba _2−x SiO ₄ : Eu (where 0 ≦ x ≦ 2) in order to improve color rendering. A dispersion in which two or more kinds of phosphors having different x values are mixed and dispersed in a transparent resin may be potted on the blue LED.

  In the above-described embodiment, the case where an LED is used as a blue light source in the light source device has been described as an example. However, another light emitter may be used as a blue light source.

  Further, for example, in the above-described embodiment, as an example of the light source device, an example in which only a blue light source is provided as a preferable configuration capable of suppressing deterioration of the resin of the light guide unit has been described. The present invention is not limited, and for example, the present invention can be variously modified and modified such as having both an ultraviolet light source and a blue light source, and a phosphor can be excited by both the light sources. sell.

  As described above, according to the present invention, it is possible to provide a light emitting composition that can be suitably used for various applications. By using this light emitting composition, stable light emission luminance and chromaticity can be obtained. A light source device that emits white light and a display device having the same can be provided.

It is sectional drawing explaining the luminescent composition and light source device using the same in embodiment of this invention. It is sectional drawing explaining the structure of a light source device and a display apparatus using the same same as the above. It is a figure which shows the manufacturing process of a luminescent composition same as the above. In the first embodiment of the present invention, SrBaSiO additives were added _4: the light emitting composition having a Eu, shows the amount of the additive, the relationship between the emission intensity of the emission spectrum of the luminescent composition It is. It is a figure which shows the excitation spectrum of the light emitting composition which has a fluorescent substance single-piece | unit, and the light emitting composition which has a fluorescent substance to which magnesium chloride was added. It is a figure which shows the excitation spectrum of the light emitting composition which has a fluorescent substance single-piece | unit, and the light emitting composition which has a fluorescent substance to which magnesium chloride was added. It is a figure which shows the light emission spectrum of the light emitting composition which has a fluorescent substance simple substance, and the light emitting composition which has the fluorescent substance to which magnesium chloride was added. In the third embodiment of the present invention, SrBaSiO Mg salts were added _4: Eu alone, and, CaAlSiN _3: is a diagram showing the reliability test results for moisture resistance of Eu alone. Ibid, SrBaSiO Mg salts were added _4: Eu alone and CaAlSiN _3: Eu-body itself is a diagram illustrating a reliability test results for the moisture resistance of the white LED in combination with a blue LED. Ibid, SrBaSiO Mg salts were added _4: is an electron micrograph showing a light emitting composition powder glass layer is formed is composed on the surface of the Eu phosphor. In the luminescent composition in which a glass layer is formed on the surface of SrBaSiO ₄ : Eu to which an Mg salt is added, the emission spectrum changes before and after the formation of the glass layer. Ibid, SrBaSiO Mg salts were added _4: In the light emitting composition having a glass layer is formed is constituted on the surface of Eu, which is a diagram illustrating a reliability test result as to whether or not the moisture resistance of the glass layer. Same as above, reliability test results on moisture resistance of white LED in which a light emitting composition composed of a glass layer is formed on the surface of SrBaSiO ₄ : Eu to which Mg salt is added and CaAlSiN ₃ : Eu alone is combined with a blue LED It is a figure explaining. It is a schematic sectional drawing explaining LED in a prior art. It is a figure explaining a light emitting element same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 2 ... Light source device, 3 ... Optical apparatus, 4 ... Reflector, 5 ... Reflector,
6 ... light emitter, 7 ... light guide, 9 ... diffusion sheet, 10 ... deflecting plate, 11 ... TFT glass substrate,
12 ... dot electrode, 13 ... liquid crystal layer, 14 ... alignment film, 15 ... electrode, 18 ... glass substrate,
16 ... Black matrix, 17a ... First color filter, 19 ... Deflection plate,
17b ... second color filter, 17c ... third color filter, 22 ... glass layer,
20: Sr _x Ba _2-x SiO ₄ : Eu (first phosphor) to which Mg salt is added,
24 ... CaAlSi ₃ : Eu (second phosphor), 26 ... transparent resin, 28 ... blue LED,
30, 32 ... Electrode, 34 ... Package, 38 ... Luminescent composition, 40 ... Light source device

Claims (13)

It is represented by at least one magnesium salt selected from the group consisting of magnesium chloride, magnesium carbonate, magnesium sulfate, and magnesium fluoride and Sr _x Ba _2-x SiO ₄ : Eu (where 0 ≦ x ≦ 2). Light emission in which a glass layer containing at least silicon (Si) and oxygen (O) is formed on the surface of a phosphor composition obtained by mixing a phosphor that emits fluorescence in the green region excited by blue light. Composition.   2. The luminescent composition according to claim 1, wherein a value of (intensity at a wavelength of 450 nm) / (intensity at a wavelength of 370 nm) relating to an excitation spectrum is 0.67 or more and 0.83 or less.   The luminescent composition according to claim 1, wherein an intensity at a wavelength of 450 nm related to an excitation spectrum is 1.5 times or more and 2.1 times or less as compared with an intensity at a wavelength of 450 nm in the single phosphor.   The luminescent composition according to claim 1, wherein an amount of the magnesium salt added is 1 mol or more and 30 mol or less with respect to 100 mol of the phosphor.   The luminescent composition according to claim 1, wherein the amount of the magnesium salt added is 3 mol or more and 15 mol or less with respect to 100 mol of the phosphor.   The luminescent composition according to claim 1, wherein the Eu concentration is 1 mol% or more and 9 mol% or less.   The luminescent composition according to claim 1, wherein the Eu concentration is 2 mol% or more and 5 mol% or less. The luminescent composition according to any one of claims 1 to 7, wherein the first luminescent composition uses the phosphor as a first phosphor,
A second luminescent composition comprising a second phosphor;
A blue light source that emits blue light; from the second light-emitting composition excited by the blue light; the fluorescence in the green region emitted from the first light-emitting composition excited by the blue light; A light source device that emits white light by mixing emitted fluorescence and the blue light.   The light source device according to claim 8, wherein the second light emitting composition is a phosphor that emits red region fluorescence when excited by the green region fluorescence and the blue light. The light source device according to claim 9, wherein the second phosphor is CaAlSiN ₃ : Eu.   The light source device according to claim 8, wherein the glass layer is formed on a surface of the second phosphor.   A display device comprising the light source device according to claim 8, wherein the light source device irradiates a pixel portion in which a plurality of pixels are arranged.   The display device according to claim 12, wherein the light source device is a backlight that irradiates the pixel portion from its back surface.

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