JP2008150518A - Wavelength conversion member and light emitting device - Google Patents

Abstract

Disclosed are a wavelength conversion member with improved dispersibility of phosphor particles in a medium, and a light emitting device with good color efficiency and no color unevenness.
Phosphor particles formed of oxynitride or nitride, a coating covering the phosphor particles and having a dielectric constant larger than that of the phosphor particles, and phosphor particles covered with the coating are dispersed. A light emitting device comprising: a wavelength conversion member provided with a medium; a semiconductor light emitting element; and the wavelength conversion member of the present invention disposed so that light emitted from the semiconductor light emitting element is incident thereon.
[Selection] Figure 1

Description

  The present invention relates to a wavelength conversion member containing phosphor particles, and a light emitting device in which the wavelength conversion member and a semiconductor light emitting element are combined.

  A light-emitting device that converts light emitted from a semiconductor light-emitting element such as a light-emitting diode (LED) with a phosphor is small in size and consumes less power than an incandescent light bulb, so that it is practically used as a light source for various display devices or lighting devices. Development of high efficiency or high reliability is being carried out.

  Japanese Patent Application Laid-Open No. 2002-171000 (Patent Document 1) emits white light using a semiconductor light emitting element that emits light having a wavelength of 390 to 420 nm and a phosphor that is excited by light emitted from the semiconductor light emitting element. A light emitting device is disclosed. Various phosphors of oxides and sulfides are used as phosphors that emit light by excitation light having a wavelength of 390 to 420 nm.

  However, depending on the phosphor, for example, a phosphor containing sulfide may react with moisture in the air and be hydrolyzed. Due to such deterioration of the phosphor, the service life of the light emitting device is reduced. As a countermeasure, for example, JP 2002-223008 A (Patent Document 2) discloses a phosphor having a coating film.

  In recent years, examples of oxynitride and nitride phosphors have been disclosed in JP 2002-363554 A and JP 2003-206481 A in place of oxide or sulfide phosphors. It is disclosed in Patent Document 4). These phosphors are excited by light with a wavelength of 390 to 420 nm to obtain high-efficiency light emission, and have excellent characteristics such as high stability and water resistance, and little fluctuation in light emission efficiency due to changes in use temperature. Many have.

In order to further improve the heat resistance of the nitride phosphor, it is disclosed in Japanese Patent Application Laid-Open No. 2004-161807 (Patent Document 5) that a coating of a metal nitride-based or metal oxynitride-based material is provided. According to Patent Document 5, (Sr _a , Ca _1-a ) _x Si _y O _z N _{{(2/3) x + (4/3) y- (2/3) z}} is used as the oxynitride phosphor _. : Eu (x = 2, y = 5) is easily baked and deteriorated, so this phosphor is covered with a coating containing N element. As the film containing N element, a metal nitride-based material containing nitrogen and a metal such as aluminum, silicon, titanium, boron, zirconium, or an organic resin containing N element such as polyurethane or polyurea is used. The nitride-based phosphor in which the film containing N element is not formed has its luminous efficiency drastically lowered by heating to 200 to 300 ° C., whereas nitriding is achieved by providing a film containing N element. It is said that the heat resistance is improved by reducing the decomposition of nitrogen in the material fluorescent material by supplying nitrogen.

JP-A-2004-71357 (Patent Document 6) discloses that phosphors are arranged in the order of a light emitting element, a red phosphor, a green phosphor, and a blue phosphor to emit light from a phosphor closer to the light emitting element. A light emitting device in which reabsorption of light is suppressed is disclosed.
JP 2002-171000 A JP 2002-223008 A JP 2002-363554 A JP 2003-206481 A JP 2004-161807 A JP 2004-71357 A

  As described above, conventionally, phosphor particles are covered with a coating for the purpose of improving the chemical stability and heat resistance of the phosphor. However, when a coating is provided on the phosphor particles, the coating may affect the dispersibility of the phosphor particles in a medium such as a resin. For example, when phosphor particles covered with a coating are dispersed in a resin, secondary aggregation of the phosphor particles occurs in the resin, and it is considered that the fluorescent color unevenness or light emission efficiency is reduced by this influence. .

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to form an oxynitride or a nitride in consideration of an influence on a medium such as a resin in which phosphor particles are dispersed. It is another object of the present invention to provide a wavelength conversion member that improves the dispersibility of phosphor particles in a medium by covering the phosphor particles with a suitable coating.

  It is another object of the present invention to provide a light emitting device that has no color unevenness and good luminous efficiency.

  The wavelength conversion member of the present invention includes phosphor particles formed of oxynitride or nitride, a coating covering the phosphor particles and having a larger dielectric constant than the phosphor particles, and a phosphor covered with the coating And a medium in which particles are dispersed.

  The wavelength conversion member of the present invention is preferably one using the following phosphor particles (1) or (2).

(1) The phosphor particles are formed of oxynitride containing Si, Al, O, N and one or more lanthanoid rare earth elements.
(2) The phosphor particles are formed of a nitride containing Ca, Si, Al, N and one or more lanthanoid rare earth elements.

  The film covering the phosphor particles used in the wavelength conversion member of the present invention is preferably formed of a metal oxide, and the metal oxide is more preferably magnesium oxide or aluminum oxide.

  The thickness of the coating covering the phosphor particles used in the wavelength conversion member of the present invention is preferably 0.05 to 3 μm.

The medium used for the wavelength conversion member of the present invention is preferably a silicone resin.
The wavelength conversion member of the present invention is covered with the coating, and the first phosphor particles having a fluorescence peak wavelength of 400 to 500 nm and the second fluorescence having a fluorescence peak wavelength of 500 to 600 nm. It is preferable that the body particles and the third phosphor particles covered with the coating film and having a fluorescence peak wavelength of 600 to 700 nm are dispersed in the medium.

  The wavelength conversion member of the present invention is covered with the coating, and the first wavelength conversion member in which phosphor particles having a fluorescence peak wavelength of 400 to 500 nm are dispersed in the medium, and the coating is covered with the fluorescence. The phosphor particles having a peak wavelength of 500 to 600 nm are covered with the second wavelength conversion member dispersed in the medium, and the phosphor particles having a peak wavelength of fluorescence of 600 to 700 nm are contained in the medium. A third wavelength conversion unit that is dispersed may be provided.

  The present invention also provides a light emitting device including a semiconductor light emitting element and the above-described wavelength conversion member of the present invention arranged so that light emitted from the semiconductor light emitting element is incident thereon.

  In the light emitting device of the present invention, the wavelength conversion member is covered with the coating as described above, and the first wavelength conversion member in which phosphor particles having a fluorescence peak wavelength of 400 to 500 nm are dispersed in the medium; A second wavelength converting member in which phosphor particles having a fluorescence peak wavelength of 500 to 600 nm are dispersed in the medium, and a phosphor having a fluorescence peak wavelength of 600 to 700 nm. When the particles include a third wavelength conversion unit dispersed in the medium, it is preferable to realize the following (1) or (2).

(1) The semiconductor light emitting element and the light emitted from the semiconductor light emitting element are arranged so as to be incident in the order of the third wavelength converting member, the second wavelength converting member, and the first wavelength converting member. ,
(2) The semiconductor light emitting element and the light emitted from the semiconductor light emitting element are arranged so as to be incident in the order of the second wavelength conversion member, the third wavelength conversion member, and the first wavelength conversion member. .

  Further, the semiconductor light emitting element in the light emitting device of the present invention is preferably either of the following (1) or (2).

(1) The emission peak wavelength of the semiconductor light emitting device is 370 to 480 nm.
(2) The emission peak wavelength of the semiconductor light emitting device is 300 to 420 nm.

  The semiconductor light emitting element in the light emitting device of the present invention is more preferably a semiconductor light emitting element formed of a GaN-based semiconductor.

  According to the present invention, in a wavelength conversion member in which phosphor particles formed of oxynitride or nitride are dispersed in a medium such as a resin, a film having a dielectric constant larger than that of the phosphor particles (preferably Is formed of a metal oxide such as magnesium oxide or aluminum oxide), so that the dispersibility when the phosphor particles are dispersed in a medium is improved. By combining such a wavelength conversion member of the present invention with a semiconductor light emitting element, it is possible to provide a light emitting device having no color unevenness and good light emission efficiency.

  FIG. 1 is a cross-sectional view schematically illustrating a preferred example of the wavelength conversion member 1 of the present invention, and FIG. 2 schematically illustrates a preferred example of the phosphor particles 2 on which the coating 3 used in the present invention is formed. It is sectional drawing shown. As shown in FIGS. 1 and 2, the wavelength conversion member 1 of the present invention has a basic structure in which phosphor particles 2 covered with a coating 3 are dispersed in a medium 4. As the phosphor particles 2 in the present invention, particles formed of oxynitride or nitride are used.

When the phosphor particles 2 are formed of oxynitride, the phosphor particles 2 are not particularly limited as long as they contain at least O (oxygen) and N (nitrogen) as composition elements, but Si (silicon), Al It is desirable that the phosphor particles include (aluminum), O, N, and one or more lanthanoid rare earth elements as composition elements. Here, examples of the lanthanoid rare earth element contained in the oxynitride include La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu. (Europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium) and the like, and light emission in the phosphor particles Acts as a center. By using phosphor particles using an oxynitride having such a composition element, a wavelength conversion member having excellent wavelength conversion efficiency can be realized as described later. Note that the phosphor particles formed of the oxynitride are specifically a JEM phosphor (composition formula: La _1-x Al (Si _6-z , Al _z ) N _10-z O activated with Ce). _z : Ce ³⁺ _{x and the} like, and β sialon activated by Eu (composition formula: Si _{3 -z} Al _z N _{4 -z} O _z : Eu ²⁺ ) can be exemplified.

Further, when the phosphor particles 2 are formed of nitride, there is no particular limitation as long as it contains at least N as a composition element, but Ca (calcium), Si, Al, N, and one or two of them. The phosphor particles preferably contain the above lanthanoid rare earth element as a composition element. Here, examples of the lanthanoid rare earth element contained in the nitride include La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb. And acts as a luminescent center in the phosphor particles. By using phosphor particles using a nitride having such a composition element, a wavelength conversion member having excellent wavelength conversion efficiency can be realized as will be described later. Specific examples of the phosphor particles formed of the nitride include CaAlSiN phosphors activated by Eu (composition formula: CaAlSiN ₃ : Eu ²⁺ ) and the like.

  The shape of the phosphor particles 2 used in the present invention is not particularly limited, and those having an appropriate shape such as an indeterminate shape, a spherical shape, and a cross-sectional square shape are used. Usually, as shown in the example shown in FIG. Are indefinite, and some of them have a shape close to a sphere.

  The size of the phosphor particles 2 used in the present invention is not particularly limited, but the particle diameter is preferably in the range of 3 to 20 μm, more preferably in the range of 5 to 15 μm. . This is because the luminous efficiency tends to decrease when the particle diameter of the phosphor particles 2 is less than 3 μm, and when the particle diameter of the phosphor particles 2 exceeds 20 μm, the phosphor particles are replaced with resin. This is because they tend to settle immediately when dispersed in a medium such as. The particle diameter of the phosphor particles 2 refers to a value (median diameter) measured using, for example, a laser diffraction particle size distribution measuring apparatus by dispersing the phosphor particles in pure water to which a dispersant is added.

  The phosphor particles 2 in the present invention are covered with a coating 3 as shown in FIG. Here, as the coating 3, a material having a dielectric constant larger than that of the phosphor particles 2 is used. The phosphor particles 2 formed of the above-described oxynitride or nitride usually have a dielectric constant of 7, so that the coating film 3 may have a dielectric constant larger than this value. The coating 3 preferably has a dielectric constant that is one or more larger than the dielectric constant of the phosphor particles 2.

  In the wavelength conversion member of the present invention, the phosphor particles 2 are covered with the coating 3 having a dielectric constant larger than that of the phosphor particles 2 as described above, whereby the phosphor 4 is applied to the medium 4 formed of a resin or the like. Dispersibility when the particles 2 are dispersed is improved. The relationship between the dielectric constant and the dispersibility improvement of this preferred coating 3 is explained as follows using the zeta potential. Ions with opposite charges gather around charged particles in the solution. The potential of the charge layer that moves with the particles is called the zeta potential and is generally used as an indicator of the dispersion stability of the particles in the solution. It has been. When the absolute value of the zeta potential is increased, the electric repulsive force between the particles is increased, the aggregation of the particles can be prevented, and the dispersion stability of the particles is increased. Conversely, when the zeta potential is close to 0, the particles tend to aggregate. Even particles that easily aggregate can be prevented from being aggregated by an electric repulsion force by coating a substance having a high dielectric constant.

Thus, for example, by covering the oxynitride phosphor particles (dielectric constant: 7) with a film formed of, for example, magnesium oxide (dielectric constant: 9), the absolute value of the zeta potential can be increased. As will be described later in Examples, a wavelength conversion member is formed using α-sialon (composition formula: Ca _0.25 Ce _0.25 (Si, Al) ₁₂ (O, N) ₁₆ ) activated with Ce as oxynitride phosphor particles. When manufactured, the oxynitride phosphor particles in which the coating was formed using magnesium oxide, whereas the absolute value of the zeta potential when using the oxynitride phosphor particles in which the coating was not formed was 25 mV When z is used, the absolute value of the zeta potential is improved to 60 mV. The absolute value of this zeta potential can be measured, for example, by dispersing phosphor particles in a solvent and using a zeta potential measuring device based on electrophoresis. As described above, when phosphor particles covered with a film having a large dielectric constant are dispersed in a medium such as a resin as in the present invention, aggregation of the phosphor particles does not occur, and the dispersibility of the phosphor particles is improved. Be improved.

  Further, by forming the above-described film, the non-luminescent process on the surface of the phosphor particles (excited electrons do not transition to the non-excited state due to the transition accompanied by light emission and do not emit light through the surface level). Therefore, it is possible to reduce the surface level that causes the non-excited state). Furthermore, by forming the above-described coating film, the coating film functions as a protective film for the phosphor particles, so that it is possible to realize a wavelength conversion member excellent in luminous efficiency and long-term stability of chromaticity and a light-emitting device described later. An effect is also produced.

  The material for forming the coating 3 used in the wavelength conversion member of the present invention is not particularly limited as long as it has a dielectric constant larger than that of the phosphor particles formed of oxynitride or nitride as described above. Although not preferred, metal oxides are preferred. Since metal oxides are generally transparent and stable, they are suitable as coating materials for oxynitride phosphor particles or nitride phosphor particles. Examples of the metal oxide include magnesium oxide (dielectric constant: 9, refractive index: 1.74), aluminum oxide (dielectric constant: 8.5, refractive index: 1.63), tantalum oxide (dielectric constant: 27, And refractive index: 2.3 to 2.55) and titanium oxide (dielectric constant: 100, refractive index: 2.3 to 2.55). Among them, the film 3 is formed of magnesium oxide or aluminum oxide because it has an intermediate refractive index between the refractive index of the phosphor particles (2.0) and the refractive index of the silicone resin as the medium (1.43). It is preferable to become.

  As shown in the example shown in FIG. 2, the coating 3 in the present invention is formed in a film shape by adhering metal oxide child particles to the surface of, for example, an irregular (possibly spherical) phosphor particle 2. . FIG. 3 is a cross-sectional view schematically showing another preferred example of the phosphor particle 2 having the coating 3 ′ according to the present invention, but the shape of the child particles is maintained to some extent as in the example shown in FIG. The film 3 ′ may be formed by attaching a metal oxide in the formed state. The coatings 3 and 3 ′ preferably cover the entire surface of the phosphor particle 2, but a part of the surface of the phosphor particle 2 (preferably the entire surface is preferably not in the range that does not impair the effects of the present invention). 80% or less of the surface) may be exposed.

  The thickness of the coatings 3 and 3 ′ in the present invention is not particularly limited, but is preferably in the range of 0.05 to 3 μm, and more preferably in the range of 0.1 to 1 μm. When the thickness of the coatings 3 and 3 ′ is less than 0.05 μm, the above-described effect of improving dispersibility tends to be difficult to obtain, and when the thickness of the coatings 3 and 3 ′ exceeds 3 μm, the luminous efficiency is increased. This is because there is a possibility of causing a decrease in the above. In addition, the thickness of the coating films 3 and 3 ′ indicates a value measured as follows. After the phosphor particles are dispersed in the resin, they are cured and polished with an argon ion beam to expose the cross section of the phosphor. This cross section is subjected to elemental analysis using SEM (scanning electron microscope) and EDX (energy dispersive X-ray elemental analyzer), and the average thickness covering the phosphor particles is determined from the mapping image of the obtained element. calculate.

  In the wavelength conversion member 1 of the present invention, the medium 4 for dispersing the phosphor particles 2 covered with the above-described coating 3 is conventionally used in the art such as a resin material such as a silicone resin and an epoxy resin, and a glass material. Any appropriate material widely used can be used without particular limitation, but it is preferable that the medium 4 is formed of a resin material, particularly a silicone resin. This is because the silicone resin has a siloxane bond (Si—O) as a skeleton, and therefore is hardly deteriorated by light from blue to near ultraviolet used as excitation light of the phosphor.

  In the wavelength conversion member 1 of the present invention, the amount of the phosphor particles 2 covered with the coating 3 dispersed in the medium 4 is not particularly limited, but is preferably in the range of 2 to 25% by weight. More preferably, it is in the range of 5 to 20% by weight. When the amount of the phosphor particles 2 dispersed in the medium 4 is less than 2% by weight, the emission intensity tends to decrease, and the amount of the phosphor particles 2 dispersed in the medium 4 is 25. This is because the emission intensity tends to decrease even when the content exceeds wt%.

  The wavelength conversion member of the present invention may be realized by a configuration in which a plurality of types of phosphor particles are dispersed in one medium. Preferably, a first phosphor particle having a fluorescence peak wavelength of 400 to 500 nm, a second phosphor particle having a fluorescence peak wavelength of 500 to 600 nm, and a third phosphor particle having a fluorescence peak wavelength of 600 to 700 nm. A wavelength conversion member having a structure in which phosphor particles are dispersed in a medium in a state where all the phosphor particles are covered with a film as described above is exemplified. In this case, the coating covering each of the first phosphor particles, the second phosphor particles, and the third phosphor particles may be made of different materials as described above, or may be made of the same material. Also good. When a wavelength conversion member is realized with a configuration in which a plurality of types of phosphor particles are dispersed in one medium as described above, each phosphor particle is dispersed in the medium so that the total amount thereof is within the above-described range. It is preferable to be made.

Here, as the first phosphor particles having a fluorescence peak wavelength of 400 to 500 nm, among the above-described oxynitride or nitride phosphor particles, for example, a JEM phosphor activated with Ce (composition formula: La _{1 -x Al (Si 6-z,} Al z) N 10-z O z: such as Ce ³⁺ _x) blue phosphor particles, such as are exemplified. As the second phosphor particles having a fluorescence peak wavelength of 500 to 600 nm, among the above-described oxynitride or nitride phosphor particles, for example, a phosphor made of β-sialon activated Eu (composition formula: Si _{3-z Al z N 4-} z O z: etc. Eu ²⁺⁾ green phosphor particles, such as are exemplified. Furthermore, as the third phosphor particles having a fluorescence peak wavelength of 600 to 700 nm, among the oxynitride or nitride phosphor particles described above, for example, a composition such as CaAlSiN ₃ : Eu ²⁺ activated Eu is used. Red phosphor particles are exemplified. Here, the peak wavelength of fluorescence of each phosphor particle indicates a value measured using, for example, a spectrofluorometer F-4500 (manufactured by Hitachi, Ltd.).

  The wavelength conversion member of the present invention may also be realized by a configuration in which different types of phosphor particles are dispersed in a plurality of wavelength conversion members. Preferably, a first wavelength conversion member in which phosphor particles having a fluorescence peak wavelength of 400 to 500 nm (the first phosphor particles described above) are dispersed in the medium, and a fluorescence peak wavelength of 500 to 600 nm A second wavelength conversion member in which phosphor particles (second phosphor particles described above) are dispersed in the medium, and phosphor particles having a fluorescence peak wavelength of 600 to 700 nm (third phosphor particles described above). Is exemplified by a wavelength conversion member having a structure including a third wavelength conversion member dispersed in the medium. In this case, the film and the medium covering the phosphor in the first wavelength conversion member, the second wavelength conversion member, and the third wavelength conversion member may be made of different materials as described above, and are the same. It may consist of materials. The first phosphor, the second phosphor, and the third phosphor dispersed in the first wavelength conversion member, the second wavelength conversion member, and the third wavelength conversion member, respectively, are the same as described above. Things can be used.

  The wavelength conversion member of the present invention is not particularly limited as to its shape, but is preferably formed into a sheet-like material. As described above, when the wavelength conversion member of the present invention is composed of a plurality of wavelength conversion members (for example, first to third wavelength conversion members), it can be formed into a sheet of multiple layers. As will be described later, when a light emitting device integrated with a semiconductor light emitting element is realized, a space in which the semiconductor light emitting element, the electrode (the semiconductor light emitting element is electrically connected), and the mirror are surrounded by them. A single-layer or multiple-layer wavelength conversion member may be formed on a base material provided in advance so as to fill the space. Further, the thickness of the wavelength conversion member is not particularly limited.

  FIG. 4 is a cross-sectional view schematically showing a light emitting device 21 of a preferred example of the present invention. The present invention also provides a light-emitting device that includes the semiconductor light-emitting element and includes the above-described wavelength conversion member of the present invention that is arranged so that light emitted from the semiconductor light-emitting element is incident thereon. As described above, the light emitting device 21 of the present invention has excellent wavelength conversion efficiency by including the wavelength conversion member 1 having improved dispersibility of the phosphor particles in the medium.

  In FIG. 4, the above-described first phosphor particles 23 having a fluorescence peak wavelength of 400 to 500 nm, the second phosphor particles 24 having a fluorescence peak wavelength of 500 to 600 nm, and a fluorescence peak wavelength of 600 are shown. In the example, the third phosphor particle 25 of ˜700 nm is provided with the wavelength conversion member 22 having a structure in which the third phosphor particle 25 is dispersed in the medium 29 while being covered with the coatings 26, 27, and 28 as described above. A light emitting device 21 is shown. The light emitting device 21 of the present invention includes a semiconductor light emitting element 30, and the wavelength conversion member 22 described above is arranged so that light emitted from the semiconductor light emitting element 30 is incident (in the example shown in FIG. 4, the semiconductor light emitting element). 30 is sealed by the wavelength conversion member 22). The light emitting device 21 shown in FIG. 4 includes a base 31, electrodes 32 and 33 formed on the surface of the base 31, and a mirror 34, and the semiconductor light emitting element 30 is electrically connected to the electrodes 32 and 33. It becomes.

  According to the light emitting device 21 of the present invention as described above, by mixing the three types of phosphor particles each having a coating formed on the wavelength conversion member, substantially white is exhibited (chromaticity coordinate x = 0.32). ˜0.34, chromaticity coordinates y = 0.32 to 0.34), a light emitting device can be realized. Further, according to the light emitting device 21 of the present invention, the light emitting device having a good color rendering property can emit light of the three primary colors and the half width of the emission spectrum of each phosphor is as wide as, for example, 50 nm or more. Can be realized.

  FIG. 5 is a cross-sectional view schematically showing a light emitting device 41 of another preferred example of the present invention. In the light emitting device 41 of the example shown in FIG. 5, the above-described first wavelength conversion member 42 in which the phosphor particles (first phosphor particles) 45 having a fluorescence peak wavelength of 400 to 500 nm are dispersed in the medium 51 and A second wavelength conversion member 43 in which phosphor particles (second phosphor particles) 46 having a fluorescence peak wavelength of 500 to 600 nm are dispersed in a medium 52, and phosphor particles having a fluorescence peak wavelength of 600 to 700 nm. The case where a wavelength conversion member provided with (third phosphor particle) 47 including a third wavelength conversion member 44 dispersed in a medium 53 is shown. As in the example shown in FIG. 4, the first to third phosphor particles 45, 46, 47 are covered with coatings 48, 49, 50 having a dielectric constant larger than that of the phosphor particles, respectively. . In the example shown in FIG. 5, a third wavelength conversion member 44, a second wavelength conversion member 43, and a first wavelength conversion member 42 are sequentially stacked from the semiconductor light emitting element 30 side. The light emitting device 41 in the example shown in FIG. 5 has the same configuration as the light emitting device 21 in the example shown in FIG. 4 except that such a wavelength conversion member is used. The parts having the same reference numerals are denoted by the same reference numerals and the description thereof is omitted.

  In the light emitting device 41 of the example shown in FIG. 5, the excitation light emitted from the semiconductor light emitting device 30 is changed to each color by the third wavelength converting member 44, the second wavelength converting member 43, and the first wavelength converting member 42. Converted. At this time, the light emitted from the semiconductor light emitting element 30 is configured to be incident in the order of the third wavelength conversion member 44, the second wavelength conversion member 43, and the first wavelength conversion member 42. The light emitted from the third wavelength conversion member 44 including the third phosphor particles 47 having a peak wavelength of 600 to 700 nm includes the second phosphor particles 46 having a fluorescence peak wavelength of 500 to 600 nm. The second wavelength conversion member 43 and the first wavelength conversion member 42 including the first phosphor particles 45 having a fluorescence peak wavelength of 400 to 500 nm are difficult to be absorbed. The light emitted from the second wavelength conversion member 43 including the second phosphor particles 46 having a fluorescence peak wavelength of 500 to 600 nm is a first phosphor having a fluorescence peak wavelength of 400 to 500 nm. It is difficult for the first wavelength conversion member 42 including the particles 45 to be absorbed. This is due to the fact that the phosphor generally has a smaller light absorptance in the longer wavelength region than the wavelength of fluorescence compared to the light absorptivity at the wavelength at which the phosphor emits fluorescence (see Patent Document 6). For this reason, in the light-emitting device 41 of the example shown in FIG. 5, the light absorption by each wavelength conversion member can be reduced, and visible light can be light-emitted efficiently.

  Furthermore, in the light emitting device 41 of the present invention, since the first to third phosphor particles 45, 46, 47 are covered with the coatings 48, 49, 50, respectively, reflection of light on the surface of the phosphor particles is small. As a result, since the reabsorption of fluorescence increases, the merit of reducing the reabsorption due to such an arrangement as described above increases. As a result, the three primary colors can be emitted, and the half-value width of the emission spectrum of each phosphor particle is wide, for example, 50 nm or more in the case of oxynitride phosphors and nitride phosphors. A light emitting device that is favorable can be realized.

  FIG. 6 is a cross-sectional view schematically showing another preferred example of the light emitting device 61 of the present invention. In the light emitting device 61 of the example illustrated in FIG. 6, the light emitted from the semiconductor light emitting element 30 is incident on the second wavelength conversion member 43, the third wavelength conversion member 44, and the first wavelength conversion member 42 in this order. Except for the configuration, it is the same as the light-emitting device 41 of the example shown in FIG. 5, and parts having the same configuration are denoted by the same reference numerals and description thereof is omitted. The light emitting device 61 in the example shown in FIG. 6 has a second wavelength in which phosphor particles (second phosphor particles) 46 having a fluorescence peak wavelength of 500 to 600 nm are dispersed in the medium 52 from the semiconductor light emitting element 30 side. The conversion member 43, the third wavelength conversion member 44 in which phosphor particles (third phosphor particles) 47 having a fluorescence peak wavelength of 600 to 700 nm are dispersed in the medium 53, and the fluorescence peak wavelength is 400 to 500 nm. The first wavelength conversion member 42 in which the phosphor particles (first phosphor particles) 45 are dispersed in the medium 51 is sequentially laminated.

  In the present invention, even when the first to third wavelength conversion members 42, 43, and 44 are arranged as shown in FIG. 6, the fluorescence is low and the luminous efficiency is slightly inferior to other colors. By disposing the first phosphor particles 45 having a peak wavelength of 400 to 500 nm at positions away from the semiconductor light emitting element 30, the first phosphor particles 45 including the second phosphor particles 46 having a peak wavelength of fluorescence of 500 to 600 nm are included. The reabsorption of fluorescence from the first phosphor particles 45 in the second wavelength conversion member 43 and the third phosphor particles 47 having a fluorescence peak wavelength of 600 to 700 nm can be suppressed. As described above, the first wavelength conversion member 42 including the first phosphor particles 45 having a fluorescence peak wavelength of 400 to 500 nm with a large absorption of excitation light is used as the uppermost layer, whereby the second phosphor particles 46. Fluorescence having a peak wavelength from 500 to 600 nm and fluorescence having a peak wavelength from 600 to 700 nm from the third phosphor particle 47 can be efficiently extracted, and a white light emitting device having excellent wavelength conversion efficiency as a whole is realized. can do. Also, such a light emitting device 61 can emit the three primary colors, and has a good color rendering property because the half-value width of each phosphor is wide, for example, 50 nm or more.

  As the semiconductor light emitting element 30 used in the light emitting devices 21, 41, and 61 of the present invention, any appropriate one that has been widely used in the art can be used. In view of conversion efficiency, it is preferable to use a light emission peak wavelength in the range of 370 to 480 nm, and it is more preferable to use a light emission peak wavelength in the range of 390 to 420 nm (purple to near ultraviolet). Such a semiconductor light emitting device 30 preferably uses a GaN-based semiconductor (a semiconductor containing at least Ga and N and using Al, In, an n-type dopant, a p-type dopant, or the like as necessary), and is particularly suitable. An example is an LED made of a GaN-based semiconductor having an emission peak wavelength of 405 nm.

  Of course, a blue light source (having a wavelength peak wavelength of 420 to 480 nm, for example, about 460 nm) may be used as the semiconductor light emitting element 30 in the present invention. In this case, there is an advantage that a light emitting device exhibiting blue and white can be realized without having blue phosphor particles. Also, with the current technology, the efficiency of the blue phosphor is slightly inferior to other phosphors (red phosphor, green phosphor, etc.), but using the blue light source increases the overall luminous efficiency. There is also an advantage of being able to.

  Further, as the semiconductor light emitting element 30, a semiconductor light emitting element made of an organic semiconductor, a zinc oxide semiconductor or the like may be used in addition to a semiconductor light emitting element made of a GaN-based semiconductor, or a semiconductor laser may be used.

  The method for producing the wavelength conversion member and the light-emitting device of the present invention is not particularly limited, and can be produced by an appropriate method widely used in the art. For example, first, the child particles of the film forming material are attached to the phosphor particles to form a film covering the phosphor particles. Next, the phosphor particles on which the film is formed and the medium forming material (for example, liquid silicone resin) are added and mixed uniformly, and then heated for a predetermined time (for example, 120 ° C. when the medium is formed of silicone resin). For 60 minutes) to cure the medium forming material and form the medium. When the wavelength conversion member 1 as shown in the example shown in FIG. 1 is manufactured, the medium after curing may be formed into a sheet using an appropriate method known in the art. When used in the light emitting device as in the example shown in FIGS. 4 to 6, for example, a space formed by the semiconductor light emitting element 30, the electrodes 32 and 33, and the substrate 31 provided on the mirror 34 is formed. A wavelength conversion member is produced by injecting a medium forming material in which phosphor particles having a film formed so as to be filled are uniformly mixed. At this time, when the first to third wavelength conversion members are manufactured as shown in FIGS. 5 and 6, the wavelength conversion members may be sequentially manufactured. In addition, as shown in FIG. 4, when the wavelength conversion member in which the first to third phosphor particles each covered with a film are dispersed in the medium is formed, the first covered each with the film. The third phosphor particles may be added to the medium forming material and mixed uniformly to produce one wavelength conversion member.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these.

<Example 1>
As shown in FIG. 2, β-sialon phosphor activated by Eu having an irregular shape (composition formula: Si _{3 -z} Al _z N _{4 -z} O _z : Eu ²⁺ ) is oxidized into green phosphor particles 2. Magnesium child particles were deposited and covered with coating 3. The thickness of the coating 3 was about 0.5 μm when the weight ratio of magnesium oxide was 0.1. Next, the green phosphor particles 2 on which the above-described coating 3 is formed are added to the liquid silicone resin at a silicone resin / phosphor particle weight ratio of 100 g / 10 g and mixed uniformly. It was molded into a sheet of 5 mm and cured by heating at 120 ° C. for 60 minutes to produce the wavelength conversion member 1 shown in FIG.

<Comparative Example 1>
A wavelength conversion member was formed in the same manner as in Example 1 except that no film was formed.

<Evaluation>
About the wavelength conversion member produced in Example 1 and Comparative Example 1, the dispersibility was evaluated as follows. 0.5-g each of β-sialon phosphor and β-sialon phosphor coated with magnesium oxide were each uniformly dispersed in 5 g of silicone resin and placed in a glass tube, and a sedimentation test was performed. After leaving for 48 hours from the uniformly dispersed state, the heights of the separated supernatants were compared. The height of the supernatant of the β-sialon phosphor was 2 mm, whereas the height of the supernatant of α-sialon coated with magnesium oxide was almost 0 mm. From this, it is considered that the dispersibility is improved by coating with magnesium oxide.

  Further, 0.1 g each of β-sialon phosphor and β-sialon phosphor coated with magnesium oxide were taken and dispersed in 10 g of ethanol, respectively, and zeta potential was measured (using a zeta potential measuring device by electrophoresis method). ). While it was 25 mV in Comparative Example 1 and increased to 60 mV in Example 1, it was found that the dispersibility of the phosphor particles in the medium was improved by forming the coating. This is presumably because, in Example 1, the coating 3 was formed using magnesium oxide having a dielectric constant of 9 covering the green phosphor particles 2 having a dielectric constant of 7.5.

<Example 2>
The light emitting device 21 of the example shown in FIG. 4 was produced. Blue phosphor which is a JEM phosphor (composition formula: La _1-x Al (Si _{6 -z} , Al _z ) N _10-z O _z : Ce ³⁺ _x ) activated with Ce as the first phosphor particles 23 Particles (dielectric constant: 7.5, refractive index: 2.0, peak wavelength of fluorescence: 490 nm), β sialon phosphor activated with Eu as the second phosphor particle 24 (composition formula: Si _3-z Al _z N _{4 -z} O _z : Eu ²⁺ ) green phosphor particles (dielectric constant: 7.5, refractive index: 2.0, fluorescence peak wavelength: 540 nm), Eu as the third phosphor particles 25 Using activated red phosphor particles made of CaAlSiN ₃ (dielectric constant: 7.5, refractive index: 2.0, fluorescence peak wavelength: 660 nm), these first to third phosphor particles 23, 24, 25 are covered with magnesium oxide (dielectric constant: 9.0, refractive index: 1.74), respectively, and coatings 26 and 27 , 28 was formed. Each phosphor is added to a liquid silicone resin (refractive index upon curing: 1.4) and mixed uniformly so that the weight ratio of silicone resin / total phosphor particles is 100 g / 15 g. Then, it was poured onto the substrate 31 and cured by heating at 120 ° C. for 60 minutes. In this way, the wavelength conversion member 22 in which the first to third phosphor particles 23, 24, and 25 having the coatings 26, 27, and 28 formed in the medium 29 are dispersed is formed.

  The substrate 31 is preliminarily formed with electrodes 32 and 33, a semiconductor light emitting device 30 electrically connected to the electrodes 32 and 33, and a mirror 34. The semiconductor light emitting device 30 is sealed in the medium 29. As described above, the wavelength conversion member 22 was formed. As the semiconductor light emitting element 30, an LED made of a GaN-based semiconductor having an emission peak wavelength of 405 nm (a semiconductor containing at least Ga and N and using Al, In, an n-type dopant, a p-type dopant or the like as required) is used. It was.

  In the light emitting device 21 of the example shown in FIG. 4 manufactured in this way, the first to third phosphor particles 23, 24, and 25 are formed of magnesium oxide having a dielectric constant larger than those phosphor particles. Therefore, the dispersibility in the medium 29 is improved. Further, the coatings 26, 27, and 28 are made of a silicone resin that is a material for forming the medium 29 in the wavelength conversion member 22 and magnesium oxide having a refractive index between the first to third phosphor particles 23, 24, and 25. By forming, the incident efficiency of the excitation light to the 1st-3rd fluorescent substance particle 23,24,25 and the extraction efficiency of the fluorescence from the 1st-3rd fluorescent substance particle 23,24,25 are aimed at. I was able to. Such a light-emitting device 21 can obtain light emission of chromaticity coordinates x = 0.32 and chromaticity coordinates y = 0.35, which are almost white, by blending three kinds of phosphor particles. It was. Moreover, since the three primary colors can be emitted, and the half-value width of the emission spectrum of each phosphor particle is as wide as, for example, 50 nm or more, the color rendering properties are good. Thus, phosphor particles formed of oxynitride or nitride, a coating covering the phosphor particles and having a dielectric constant larger than that of the phosphor particles, and phosphor particles covered with the coating are dispersed. By combining a wavelength conversion member provided with a medium with a semiconductor light emitting element, a small and high output light emitting device exhibiting white was obtained.

<Example 3>
The light emitting device 41 of the example shown in FIG. 5 was produced. As the first to third phosphor particles 45, 46, 47 and the coatings 48, 49, 50, the first to third phosphor particles 23, 24, 25 and the coatings 26, 27, described above in the second embodiment. The same as 28 was used.

  First, the third phosphor particles 47 (red phosphor particles) covered with the coating 50 are uniformly in a liquid silicone resin so that the weight ratio of silicone resin / phosphor particles is 100 g / 0.5 g. Then, the mixture was poured onto the substrate 31 and cured by heating at 120 ° C. for 60 minutes to form the third wavelength conversion member 44 (thickness: 0.5 mm). The substrate 31 is preliminarily formed with electrodes 32 and 33, a semiconductor light emitting device 30 electrically connected to the electrodes 32 and 33, and a mirror 34, and the semiconductor light emitting device 30 is sealed in the medium 29. As described above, the third wavelength conversion member 44 was formed. As the semiconductor light emitting element 30, an LED made of a GaN-based semiconductor having an emission peak wavelength of 405 nm was used.

  Next, the second phosphor particles 46 (green phosphor particles) covered with the coating 49 are placed in a liquid silicone resin so that the weight ratio of silicone resin / phosphor particles is 100 g / 1.4 g. It mixed uniformly, inject | poured so that it might overlap on the 3rd wavelength conversion member 44, and it was made to harden | cure by heating for 60 minutes at 120 degreeC, and the 2nd wavelength conversion member 43 was formed (thickness: 0.5 mm).

  Finally, the first phosphor particles 45 (blue phosphor particles) covered with the coating 48 are placed in a liquid silicone resin so that the weight ratio of silicone resin / phosphor particles is 100 g / 13.1 g. It mixed uniformly, inject | poured so that it might overlap on the 2nd wavelength conversion member 43, and it was made to harden | cure by heating for 60 minutes at 120 degreeC, and the 1st wavelength conversion member 42 was formed (thickness: 0.5 mm).

  Thus, as shown in FIG. 5, the light emitted from the semiconductor light emitting element 30 is incident on the third wavelength conversion member 44, the second wavelength conversion member 43, and the first wavelength conversion member 42 in this order. A light emitting device 41 configured as described above was manufactured. In such a light emitting device 41, the excitation light emitted from the semiconductor light emitting device 30 is converted into each color by the third wavelength converting member 44, the second wavelength converting member 43, and the first wavelength converting member 42, respectively. . At this time, the light emitted from the third wavelength conversion member 44 including the red phosphor particles as the third phosphor particles 47 is the second light including the green phosphor particles as the second phosphor particles 46 thereon. The wavelength conversion member 43 and the first phosphor particles 45 are less likely to be absorbed by the first wavelength conversion member 42 including blue phosphor particles. The light emitted from the second wavelength conversion member 43 including the green phosphor particles as the second phosphor particles 46 is the first wavelength including the blue phosphor particles as the first phosphor particles 45 thereon. Difficult to be absorbed by the conversion member 42. Thus, light absorption by each wavelength conversion member can be reduced and visible light can be efficiently emitted.

  Furthermore, in the light emitting device 41 of the present invention, since the first to third phosphor particles 45, 46, 47 are covered with the coatings 48, 49, 50, respectively, reflection of light on the surface of the phosphor particles is small. As a result, since the reabsorption of fluorescence increases, the merit of reducing the reabsorption due to such an arrangement as described above increases. As a result, the three primary colors can be emitted, and the half-value width of the emission spectrum of each phosphor particle is wide, for example, 50 nm or more in the case of oxynitride phosphors and nitride phosphors. A light emitting device that is favorable can be realized.

<Example 4>
A light emitting device 61 of the example shown in FIG. 6 was fabricated in the same manner as in Example 3 except that the formation order of the third wavelength converting member 44 and the second converting member 43 was reversed. The light emitting device 61 obtained in this way is such that the light emitted from the semiconductor light emitting element 30 enters the second wavelength conversion member 43, the third wavelength conversion member 44, and the first wavelength conversion member 42 in this order. Consists of. Also by this arrangement, the blue phosphor particles as the first phosphor particles 45 having low visibility and slightly lower luminous efficiency than the other colors are arranged at positions away from the semiconductor light emitting element 30, so that the second The second wavelength conversion member 43 including green phosphor particles as the phosphor particles 46 and the third wavelength conversion member 44 including red phosphor particles as the third phosphor particles 47 are inhibited from reabsorbing blue fluorescence. can do.

  Therefore, even in the light emitting device 61 manufactured in Example 4 as described above, the first wavelength conversion member 42 including the blue phosphor can be used as the uppermost layer, whereby green and red can be efficiently extracted. As a whole, a white light emitting device excellent in wavelength conversion efficiency was obtained. Thereby, the three primary colors can be emitted, and the half-value width of the emission spectrum of each phosphor is as wide as, for example, 50 nm or more, so that the color rendering is good.

  The embodiments, examples, and comparative examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is sectional drawing which shows typically the wavelength conversion member 1 of a preferable example of this invention. It is sectional drawing which shows typically a preferable example of the fluorescent substance particle 2 in which the film 3 used for the wavelength conversion member of this invention was formed. It is sectional drawing which shows typically the other preferable example of the fluorescent substance particle 2 in which the film 3 'used for the wavelength conversion member of this invention was formed. It is sectional drawing which shows typically the light-emitting device 21 of a preferable example of this invention. It is sectional drawing which shows typically the light-emitting device 41 of the other preferable example of this invention. It is sectional drawing which shows typically the light-emitting device 61 of another more preferable example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Wavelength conversion member, 2 Phosphor particle, 3, 3 'coating, 4 Medium, 21, 41, 61 Light-emitting device, 22 Wavelength conversion member, 23, 45 1st phosphor particle, 24, 46 2nd phosphor Particle, 25, 47 Third phosphor particle, 26, 27, 28, 48, 49, 50 Coating, 29, 51, 52, 53 Medium, 30 Semiconductor light emitting device, 31, 32 Electrode, 34 Mirror, 42 First Wavelength conversion member, 43 2nd wavelength conversion member, 44 3rd wavelength conversion member.

Claims (16)

  Phosphor particles formed of oxynitride or nitride, a film covering the phosphor particles and having a dielectric constant larger than that of the phosphor particles, and a medium in which the phosphor particles covered with the film are dispersed A wavelength conversion member provided.   The wavelength conversion member according to claim 1, wherein the phosphor particles are formed of oxynitride containing Si, Al, O, N and one or more lanthanoid rare earth elements.   The wavelength conversion member according to claim 1, wherein the phosphor particles are formed of a nitride containing Ca, Si, Al, N and one or more lanthanoid rare earth elements.   The wavelength conversion member in any one of Claims 1-3 whose said film is formed with the metal oxide.   The wavelength conversion member according to claim 4, wherein the metal oxide is magnesium oxide.   The wavelength conversion member according to claim 4, wherein the metal oxide is aluminum oxide.   The thickness of the said film is 0.05-3 micrometers, The wavelength conversion member in any one of Claims 1-6 characterized by the above-mentioned.   The wavelength conversion member according to claim 1, wherein the medium is a silicone resin.   The first phosphor particles covered with the coating and having a fluorescence peak wavelength of 400 to 500 nm, the second phosphor particles covered with the coating and having a fluorescence peak wavelength of 500 to 600 nm, and the coating. The wavelength conversion member according to claim 1, wherein third phosphor particles having a fluorescence peak wavelength of 600 to 700 nm are dispersed in the medium.   A first wavelength conversion member in which phosphor particles covered with the coating and having a fluorescence peak wavelength of 400 to 500 nm are dispersed in the medium, and a fluorescence having a fluorescence peak wavelength of 500 to 600 nm covered with the coating. A second wavelength conversion member in which body particles are dispersed in the medium; and a third wavelength conversion unit that is covered with the coating and phosphor particles having a fluorescence peak wavelength of 600 to 700 nm are dispersed in the medium. The wavelength conversion member in any one of Claims 1-9 provided with these.   A light-emitting device provided with a semiconductor light-emitting device and the wavelength conversion member according to claim 1 arranged so that light emitted from the semiconductor light-emitting device is incident thereon.   The semiconductor light emitting element and the light emitted from the semiconductor light emitting element are arranged so as to be incident in the order of the third wavelength conversion member, the second wavelength conversion member, and the first wavelength conversion member. A light-emitting device comprising the wavelength conversion member described.   The semiconductor light emitting element and the light emitted from the semiconductor light emitting element are arranged so as to be incident in the order of the second wavelength conversion member, the third wavelength conversion member, and the first wavelength conversion member. A light-emitting device comprising the wavelength conversion member described.   The light emitting device according to claim 11, wherein an emission peak wavelength of the semiconductor light emitting element is 370 to 480 nm.   The light emitting device according to claim 11, wherein an emission peak wavelength of the semiconductor light emitting element is 390 to 420 nm.   The light-emitting device according to claim 11, wherein the semiconductor light-emitting element is a semiconductor light-emitting element formed of a GaN-based semiconductor.

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