JP5585411B2 - Wavelength conversion element and light source including the same - Google Patents

Description

  The present invention relates to a wavelength conversion element and a light source including the same.

  In recent years, attention has been paid to next-generation light sources such as light sources using light emitting diodes (LEDs) and laser diodes (LDs), such as fluorescent lamps and incandescent lamps. As an example of such a next-generation light source, for example, in Patent Document 1 below, a wavelength conversion member that absorbs part of light from an LED and emits yellow light on the light emitting side of the LED that emits blue light. A light source in which is arranged is disclosed. This light source emits white light which is a combined light of blue light emitted from the LED and yellow light emitted from the wavelength conversion member.

JP 2000-208815 A

  In recent years, there has been an increasing demand for further increasing the luminance of a light source using such a wavelength conversion member.

  This invention is made | formed in view of this point, The objective is to aim at the high brightness improvement of the light source using a wavelength conversion member.

  The wavelength conversion element according to the present invention is formed by bundling three or more columnar wavelength conversion members in which phosphor powder is dispersed in a dispersion medium.

  When the wavelength conversion member is one in which the phosphor powder is dispersed in the dispersion medium, for example, unlike an optical member made only of glass, light incident on the wavelength conversion unit is greatly scattered in the wavelength conversion member. Tend to. For this reason, when the wavelength conversion element is composed of a single wavelength conversion member, a part of the light in the wavelength conversion member leaks out from the side surface of the wavelength conversion member, so that the light emitted from the light exit surface Strength is lowered.

  In contrast, in the present invention, three or more cylindrical wavelength conversion members are bundled. For this reason, a part of the light emitted from the side surface of a certain wavelength conversion member is reflected on the surface of the adjacent wavelength conversion member. As a result, one of the wavelength conversion members is propagated by propagating through the air layer formed between the adjacent wavelength conversion members, or entering the wavelength conversion member again and reflecting while reflecting in the wavelength conversion member. The light exits from the light exit area provided with the end of the. For this reason, in the wavelength conversion element of this invention, the leakage of the light from the side surface side of a wavelength conversion element can be suppressed, and the intensity | strength of the light radiate | emitted from a light-projection area | region can be raised. Therefore, the brightness of the light source can be increased by using the wavelength conversion element of the present invention.

The refractive index of the dispersion medium of the wavelength conversion member is preferably 1.45 or more. In that case, the refractive index difference between the wavelength conversion member and the air layer can be increased. For this reason, the reflectance at the interface can be increased and the reflection angle can be decreased, so that the emission of light from the side surface of the wavelength conversion member can be suppressed. Therefore, light leakage from the side surface side of the wavelength conversion element can be more effectively suppressed.

  From the viewpoint of more effectively suppressing light leakage from the side surface side of the wavelength conversion element, it is preferable that nine or more wavelength conversion members are bundled.

  The dispersion medium is not particularly limited as long as the phosphor powder can be dispersed. Specific examples of the dispersion medium preferably used as the dispersion medium include resin, glass, ceramics, and the like. Among these, inorganic dispersion media such as glass and ceramics are more preferably used. This is because the heat resistance of the wavelength conversion element can be improved by using the inorganic dispersion medium. For the same reason, the phosphor powder is preferably an inorganic phosphor powder.

  The light source which concerns on this invention is equipped with the wavelength conversion element which concerns on the said invention, and the light emitting element which radiate | emits the excitation light of fluorescent substance powder toward the end surface of a wavelength conversion element.

  As described above, the wavelength conversion element according to the present invention can increase the intensity of light emitted from the light exit surface. Therefore, the light source according to the present invention has high luminance.

  According to the present invention, it is possible to increase the brightness of a light source using a wavelength conversion member.

It is a schematic diagram of the light source which concerns on one Embodiment which implemented this invention. 1 is a schematic perspective view of a wavelength conversion element according to an embodiment of the present invention. It is a schematic diagram of the light source which concerns on 2nd Embodiment.

  Hereinafter, an example of the preferable form which implemented this invention is demonstrated. However, the following embodiment is merely an example. The present invention is not limited to the following embodiments.

  FIG. 1 is a schematic diagram of a light source according to the present embodiment. As shown in FIG. 1, the light source 1 includes a wavelength conversion element 11 and a light emitting element 10. The wavelength conversion element 11 emits light L2 having a longer wavelength than the light L0 when the light L0 emitted from the light emitting element 10 is irradiated. Further, a part of the light L0 is transmitted through the wavelength conversion element 11. For this reason, the wavelength conversion element 11 emits light L3 that is a combined light of the transmitted light L1 and the light L2. For this reason, the light L3 emitted from the light source 1 is determined by the wavelength and intensity of the light L0 emitted from the light emitting element 10 and the wavelength and intensity of the light L2 emitted from the wavelength conversion element 11. For example, when the light L0 is blue light and the light L2 is yellow light, white light L3 can be obtained.

  The light emitting element 10 is an element that emits excitation light of a phosphor powder described later to the wavelength conversion element 11. The kind of the light emitting element 10 is not particularly limited. The light emitting element 10 can be composed of, for example, an LED, an LD, an electroluminescence light emitting element, or a plasma light emitting element. From the viewpoint of increasing the luminance of the light source 1, the light emitting element 10 preferably emits high-intensity light. From this viewpoint, it is preferable that the light emitting element 10 is composed of an LED or an LD.

  A wavelength selection filter layer or a reflection suppression layer may be formed on at least one of the light incident region 11a and the light emitting region 11b of the wavelength conversion member.

For example, by forming the wavelength selection filter layer on the light incident region 11 a of the wavelength conversion element 11, only the light in a specific wavelength range among the light L0 emitted from the light emitting element 10 is sent to the wavelength conversion element 11. It is possible to transmit light and suppress transmission of light in other wavelength regions, and it is possible to suppress the light L2 converted by the wavelength conversion element 11 from being emitted from the light incident region 11a. The wavelength selection filter layer can be formed by, for example, a dielectric multilayer film.

  Further, for example, by forming a reflection suppressing layer on the light emitting region 11b of the wavelength conversion element 11, the light emitted from the wavelength converting element 11 is suppressed from being reflected by the light emitting region 11b, and wavelength conversion is performed. The emission rate of light emitted from the element 11 can be increased. The reflection suppression layer can be formed by, for example, a dielectric multilayer film.

  FIG. 2 is a schematic perspective view of the wavelength conversion element 11. As shown in FIG. 2, the wavelength conversion element 11 includes three or more wavelength conversion members 12 arranged to extend along the x direction. The wavelength conversion element 11 preferably includes nine or more wavelength conversion members 12, and more preferably includes 25 or more wavelength conversion members 12. Three or more wavelength conversion members 12 are bundled and fixed so that adjacent wavelength conversion members 12 are in contact with each other. In the present embodiment, the wavelength conversion member 12 is formed in a cylindrical shape. For this reason, an air layer 13 extending from the light incident region 11a to the light emitting region 11b of the wavelength conversion element 11 in the x direction is formed between adjacent wavelength conversion members 12. Each of the light incident region 11 a and the light emitting region 11 b is configured by the air layer 13 and the end face of the wavelength conversion member 12.

  The plurality of wavelength conversion members 12 may be fixed using a fixing member such as a frame, or may be fixed using an adhesive or the like.

  The wavelength conversion member 12 has a dispersion medium and a phosphor powder dispersed in the dispersion medium.

  The phosphor powder absorbs light L0 from the light emitting element 10 and emits light L2 having a longer wavelength than the light L0. The phosphor powder is preferably an inorganic phosphor powder. By using the inorganic phosphor powder, the heat resistance of the wavelength conversion member 12 can be improved.

Specific examples of inorganic phosphors that emit blue light when irradiated with excitation light having a wavelength of 300 to 440 nm include Sr ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ , (Sr, Ba) MgAl ₁₀ O _17. : Eu ^{2+ and the} like.

Specific examples of the inorganic phosphor that emits green fluorescence (fluorescence having a wavelength of 500 nm to 540 nm) when irradiated with excitation light having a wavelength of 300 to 440 nm are SrAl ₂ O ₄ : Eu ²⁺ , SrGa ₂ S _4. : Eu ^{2+ and the} like.

Specific examples of inorganic phosphors that emit green fluorescence (fluorescence having a wavelength of 500 nm to 540 nm) when irradiated with blue excitation light having a wavelength of 440 to 480 nm include SrAl ₂ O ₄ : Eu ²⁺ and SrGa ₂ S ₄ : Eu ^2+. Etc.

A specific example of a non-fluorescent material that emits yellow fluorescence (fluorescence having a wavelength of 540 nm to 595 nm) when irradiated with excitation light having a wavelength of 300 to 440 nm is ZnS: Eu ²⁺ .

Specific examples of the inorganic phosphor that emits yellow fluorescence (fluorescence having a wavelength of 540 nm to 595 nm) when irradiated with blue excitation light having a wavelength of 440 to 480 nm include Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ^{2+ and the} like. Can be mentioned.

Irradiation with ultraviolet to near ultraviolet excitation light having a wavelength of 300 to 440 nm causes red fluorescence (with a wavelength of 60
Specific examples of the inorganic phosphor that emits fluorescence of 0 nm to 700 nm include Gd ₃ Ga ₄ O ₁₂ : Cr ³⁺ , CaGa ₂ S ₄ : Mn ^{2+, and the} like.

Specific examples of inorganic phosphors that emit red fluorescence (fluorescence having a wavelength of 600 nm to 700 nm) when irradiated with blue excitation light having a wavelength of 440 to 480 nm include Mg ₂ TiO ₄ : Mn ⁴⁺ and K ₂ SiF ₆ : Mn ^4+. Etc.

The average particle diameter (D ₅₀ ) of the phosphor powder is not particularly limited. The average particle size (D ₅₀ ) of the phosphor powder is, for example, preferably about 1 μm to 50 μm, and more preferably about 5 μm to 25 μm. If the average particle size (D ₅₀ ) of the phosphor powder is too large, the emission color may be non-uniform. On the other hand, if the average particle diameter (D ₅₀ ) of the phosphor powder is too small, the emission intensity may be reduced.

  The content of the phosphor powder in the wavelength conversion member 12 is not particularly limited. The content of the phosphor powder in the wavelength conversion member 12 can be appropriately set according to the intensity of light emitted from the light emitting element 10, the light emission characteristics of the phosphor powder, the chromaticity of the light to be obtained, and the like. In general, the content of the phosphor powder in the wavelength conversion member 12 can be, for example, about 0.01% by mass to 30% by mass, and preferably 0.05% by mass to 20% by mass. It is more preferable that it is 0.08 mass%-15 mass%. When there is too much content of the phosphor powder in the wavelength conversion member 12, the porosity in the wavelength conversion member 12 will become high, and the emitted light intensity of the light source 1 may fall. On the other hand, if the content of the phosphor powder in the wavelength conversion member 12 is too small, sufficiently strong fluorescence may not be obtained.

  The dispersion medium is preferably, for example, a heat resistant resin, glass, or ceramic. Among them, an inorganic dispersion medium such as glass or ceramics that has particularly high heat resistance and hardly deteriorates due to the light L0 from the light emitting element 10 is more preferably used.

  Specific examples of the heat resistant resin include polyimide and the like. Specific examples of the glass include silicate glass, borosilicate glass, phosphate glass, and borophosphate glass. Specific examples of ceramics include metal nitrides such as zirconia, alumina, barium titanate, silicon nitride, and titanium nitride.

  As described above, in the present embodiment, three or more columnar wavelength conversion members 12 are bundled. For this reason, an air layer 13 extending from the light incident region 11 a to the light emitting region 11 b is formed between the wavelength conversion members 12. Therefore, a part of the light emitted from the side surface of a certain wavelength conversion member 12 is reflected on the surface of the adjacent wavelength conversion member 12. As a result, the light is emitted from the light emitting region 11 b of the wavelength conversion member 12 by propagating through the air layer 13, entering the wavelength conversion member 12 again, and propagating through the wavelength conversion member 12. For this reason, leakage of light from the side surface side of the wavelength conversion element 11 can be suppressed, and the intensity of light emitted from the light emitting region 11b can be increased. Therefore, the high-intensity light source 1 can be realized.

  Further, from the viewpoint of more effectively suppressing leakage of light from the side surface side of the wavelength conversion element 11, the number of wavelength conversion members 12 bundled is increased, and the air formed in the wavelength conversion element 11. It is preferable to increase the number of layers 13. Therefore, the number of the wavelength conversion members 12 bundled is preferably 9 or more, and more preferably 25 or more.

  Further, from the viewpoint of more effectively suppressing light leakage from the side surface side of the wavelength conversion element 11, the refractive index of the dispersion medium of the wavelength conversion member 12 (≈refractive index of the wavelength conversion member 12) is 1.45 or more. It is preferable that it is 1.55 or more.

  Hereinafter, other examples of preferable embodiments implemented in the present invention will be described. In the following description, members having substantially the same functions as those of the first embodiment are referred to by the same reference numerals, and description thereof is omitted.

(Second Embodiment)
FIG. 3 is a schematic diagram of a light source according to the second embodiment.

  As shown in FIG. 3, the light source 2 of the present embodiment is provided with a beam splitter 18. The light L0 from the light emitting element 10 is guided to the wavelength conversion element 11 side by the beam splitter 18. A reflection suppression layer 11c is formed in the light incident region of the wavelength conversion element 11, and a reflection layer 11d is formed on the opposite surface. The reflective layer 11d can be formed of, for example, a metal such as Ag, Al, Au, Pd, Pt, Cu, Ti, Ni, Cr, an alloy containing at least one of these metals, or a white paint.

  An adhesive layer (not shown) made of resin or solder is formed on the reflective layer 11d. The wavelength conversion element 11 and the substrate 19 made of glass, ceramics, metal, or the like are fixed via the adhesive layer. By this reflective layer 11d, a part of the light L0 and the light emitted from the wavelength conversion member are reflected to the beam splitter 18 side. Therefore, the light L3 is emitted toward the beam splitter 18 and is transmitted through the beam splitter 18 and emitted.

  As shown in FIG. 3, when the light source 2 has the substrate 19 and the wavelength conversion element 11 fixed via an adhesive layer, the wavelength conversion formed by arranging a plurality of wavelength conversion members 12 as shown in FIG. By using the element 11, peeling between the substrate 19 and the wavelength conversion element 11 due to heat generated when converting the light L0 emitted from the light emitting element 10 into the light L3 can be effectively suppressed.

DESCRIPTION OF SYMBOLS 1, 2 ... Light source 10 ... Light emitting element 11 ... Wavelength conversion element 11a ... Light incident area 11b ... Light emission area 11c ... Reflection suppression layer 11d ... Reflection layer 12 ... Wavelength conversion member 13 ... Air layer 18 ... Beam splitter 19 ... Substrate

Claims (4)

Three or more cylindrical wavelength conversion members formed by dispersing phosphor powder in a dispersion medium are bundled , the dispersion medium is glass or ceramics, and the phosphor powder is an inorganic phosphor powder. Conversion element.   The wavelength conversion element according to claim 1, wherein nine or more wavelength conversion members are bundled.   The wavelength conversion element according to claim 1 or 2, wherein the dispersion medium has a refractive index of 1.45 or more. The wavelength conversion element according to any one of claims 1 to 3 ,
A light emitting element that emits excitation light of the phosphor powder toward the end face of the wavelength conversion element;
A light source comprising

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