JP5271340B2 - Light emitting device, lighting device, and vehicle headlamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device and an illuminating device which are functionable as a small-sized light source having high luminance and high luminous flux while being used for a long period of time. <P>SOLUTION: A headlamp 1 includes a laser diode 2 which emits a laser beam and a light emitting section 5 which emits light upon receiving the laser beam from the laser diode 2. The light emitting section 5 has heat-resistant phosphor dispersed inside heat-resistant transparent sealing material. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a light emitting device that functions as a high-intensity light source, an illumination device including the light emitting device, and a vehicle headlamp.

  In recent years, semiconductor light emitting devices such as light emitting diodes (LEDs) and semiconductor lasers (LDs) are used as excitation light sources, and excitation light generated from these excitation light sources is emitted to light emitting units including phosphors. Research on light-emitting devices that use fluorescence generated by the above as illumination light has become active. Examples of techniques related to such a light emitting unit are disclosed in Patent Documents 1 to 5.

  Patent Document 1 discloses a gallium nitride LED in which a case member is formed of ceramic, a phosphor is dispersed in low-melting glass, and a filling member is low-melting glass. In this light-emitting device, each member is made of an inorganic material as described above, thereby suppressing the deterioration of the member due to light having a short wavelength and extending the life.

Patent Document 2 discloses a light-emitting device that prevents the fluorescent material from being deteriorated by moisture by dispersing fluorescent glass as a fluorescent material in a low-melting glass. As low melting glass, Nb ₂ O ₅ system, B ₂ O ₃ system, P ₂ O ₅ -F system, P ₂ O ₅ -ZnO system, SiO ₂ -B ₂ O ₃ -La ₂ O ₃ system, SiO ₂ -B _{The 2} O ₃ system is illustrated.

Patent Document 3 discloses a light emitting diode lamp provided with a phosphor dispersion member made of a low melting point glass in which a phosphor is dispersed between a transparent resin and a light emitting diode. Since the ultraviolet light emitted from the light emitting diode is reduced by the phosphor dispersion member, the deterioration of the resin due to the ultraviolet light is suppressed, and the life of the light emitting diode lamp can be extended. Examples of the low melting point glass include PbO—SiO ₂ —B ₂ O ₃ and PbO—P ₂ O ₅ —SnF ₂ .

  Patent Document 4 discloses a light emitting device including a wavelength conversion member in which a phosphor is dispersed in silicate glass. It is described that the silicate glass preferably contains at least one of alkali metal oxide, alkaline earth metal oxide, boric acid, phosphoric acid, and zinc oxide. It is described that a wavelength conversion member can be obtained by mixing phosphor and glass powder and performing hot press molding.

Patent Document 5 discloses Al ₂ O ₃ , SiO ₂ , ZrO ₂ , ZnO, ZnSe, AlN, and GaN as glasses suitable for a base material for sealing a phosphor. Examples of the phosphor include cadmium zinc sulfide activated with Cu, YAG phosphor and LAG phosphor activated with cerium. In addition, it is described that YAG, LAG, BAM, BAM: Mn, CCA, SCA, SCESN, SESN, CESN, CASBN, CaAlSiN ₃ : Eu can be used. In addition, low-melting glass (SnO—P ₂ O ₅ system, CuO—P ₂ O ₅ system, Bi ₂ O ₃ system) is used for bonding the cap and the phosphor covering the semiconductor laser element.

Japanese Unexamined Patent Application Publication No. 2004-200531 (released on July 15, 2004) JP 2004-273798 A (published September 30, 2004) Japanese Patent Laying-Open No. 2006-32500 (published February 2, 2006) JP 2007-324239 A (released on December 13, 2007) JP 2009-105125 A (published May 14, 2009)

  By using a semiconductor laser instead of a general light emitting diode as a light source for exciting the phosphor contained in the light emitting section, the excitation light can be efficiently condensed in a narrow area, so that the light source with higher brightness Can be realized. However, in the invention of the above-mentioned patent document, it is not assumed that the light emitting part is excited by high-power laser light, and if such a laser light is irradiated to the light emitting part, the light emitting part is deteriorated. The inventors of the present invention have found that this occurs.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a light-emitting device that is a compact, high-brightness, high-luminous light source and includes a light-emitting portion with high heat resistance, and the light-emitting device. It is in providing the illuminating device provided.

  In order to solve the above-described problem, a light-emitting device according to the present invention includes a semiconductor laser that emits laser light, and a light-emitting unit that receives and emits laser light emitted from the semiconductor laser. The heat-resistant phosphor is dispersed in a heat-resistant transparent sealing material.

  According to said structure, when the laser beam which the semiconductor laser radiate | emitted is irradiated to a light emission part, the said light emission part will light-emit.

  The inventors of the present invention have found that when the light emitting portion is excited with high power laser light, the light emitting portion is severely deteriorated. The deterioration of the light emitting part is mainly caused by the deterioration of the phosphor itself contained in the light emitting part and the deterioration of the sealing material surrounding the phosphor. For example, a sialon phosphor, which is an example of an oxynitride phosphor, generates light with an efficiency of 60 to 80% when irradiated with laser light, but the rest is emitted as heat. It is considered that the phosphor and the sealing material are deteriorated by this heat.

  According to said structure, the light emission part is formed by disperse | distributing a heat resistant fluorescent substance in a heat resistant transparent sealing material. Therefore, it is possible to prevent deterioration of the light emitting part due to heat, and as a result, it is possible to realize a light emitting device that functions as a light source that is small, has high brightness, and has high luminous flux and can be used for a long time.

  In addition, even when the heat-resistant phosphor is subjected to a heat treatment in a temperature range of at least 0 ° C. to 560 ° C., the quantum efficiency of the heat-resistant phosphor measured at a temperature after the heat treatment is In addition, it is preferable that the quantum efficiency measured at a certain temperature does not decrease beyond the error range.

  In general, the quantum efficiency of a phosphor decreases as the ambient temperature (environmental temperature) increases, and then recovers as the environmental temperature decreases. Usually, this change in temperature-dependent quantum efficiency (temperature dependence of quantum efficiency) occurs reversibly. However, when the phosphor is heated above a certain temperature (referred to as high heat treatment), the temperature dependence of the quantum efficiency changes, and the quantum efficiency at a predetermined temperature (for example, room temperature) after the high heat treatment is It may be lower than the quantum efficiency at a predetermined temperature. This decrease in quantum efficiency is irreversible.

  According to said structure, even if it heats to near 560 degreeC, the temperature dependence of the quantum efficiency of a heat resistant fluorescent substance hardly changes. That is, the quantum efficiency measured at a certain temperature (for example, room temperature) after the heat treatment hardly decreases compared with the quantum efficiency measured at the certain temperature before the heat treatment.

  Therefore, even when the heat-resistant phosphor is temporarily heated at a high temperature for the purpose of sealing the heat-resistant phosphor in a heat-resistant transparent encapsulant, the luminous efficiency of the heat-resistant phosphor is almost zero. It does not decline.

  Therefore, it is possible to prevent the heat-resistant phosphor from being deteriorated due to an increase in ambient temperature such as an increase in temperature accompanying the manufacture of the light emitting part.

  It should be noted that the change in quantum efficiency with respect to temperature change does not have to change at all over the entire temperature range in which quantum efficiency is measured before and after heat treatment. It suffices if the difference is within a predetermined range before and after. Alternatively, the temperature dependence of the quantum efficiency of the heat-resistant phosphor in a specific temperature range should be almost unchanged before and after the heat treatment. The specific temperature range may be appropriately set by those skilled in the art.

Further, the heat-resistant phosphor, oxynitride phosphor, it is preferred that the nanoparticle phosphor made of nitride fluorescent material or III-V compound semiconductor.

  Since these phosphors are excellent in heat resistance, a light emitting portion excellent in heat resistance can be realized.

  The heat-resistant transparent encapsulant is a low-melting glass, and the mass ratio of the heat-resistant phosphor and the heat-resistant transparent encapsulant in the light emitting part is 0.5: 100 or more, 20: It is preferable that it is 100 or less.

  Moreover, the said heat resistant transparent sealing material is organic inorganic hybrid glass, and mass ratio of the said heat resistant fluorescent substance and the said organic inorganic hybrid glass in the said light emission part is 5.13: 200 or more, 50: 200. The following is preferable.

  The inventor of the present invention has found that deterioration of the phosphor due to heat can be suppressed by adjusting the mixing ratio of the sealing material and the phosphor. Specifically, the heat-resistant transparent encapsulant is made of low-melting glass or organic-inorganic hybrid glass and has the above mixing ratio, thereby suppressing the heat generation of the light emitting part due to laser light irradiation, and the deterioration of the phosphor due to heat. Can be suppressed.

The oxynitride phosphor includes Caα-SiAlON (silicon aluminum oxynitride): Ce phosphor, Caα-SiAlON: Eu phosphor, β-SiAlON: Eu phosphor , and the nitride phosphor includes CASN: It is preferable to include EU phosphor or SCASN: Eu phosphor.

  Since these oxynitride phosphors are excellent in heat resistance, it is possible to realize a light emitting portion excellent in heat resistance.

The irradiation density of the laser beam irradiated to the light emitting portion is preferably 0.1 W / mm ² or more 50 W / mm ² or less.

  With the above configuration, illumination light having high luminance can be generated, and a light-emitting device that can be suitably applied particularly to a headlamp can be realized.

  Moreover, the lighting device provided with the said light-emitting device and the vehicle headlamp provided with the said light-emitting device are also contained in the technical scope of this invention.

  As described above, the light emitting device according to the present invention includes the semiconductor laser that emits laser light and the light emitting unit that emits light by receiving the laser light emitted from the semiconductor laser, and the light emitting unit includes a heat-resistant phosphor. Is dispersed in the heat-resistant transparent encapsulant.

  Therefore, the light emitting unit can be prevented from deteriorating, and it is possible to realize a light emitting device that functions as a light source that can be used for a long period of time.

It is a figure which shows schematic structure of the headlamp which concerns on one Embodiment of this invention. (A) is a schematic diagram showing a circuit diagram of a semiconductor laser included in the headlamp, and (b) is a perspective view showing a basic structure of the semiconductor laser. It is a figure which shows schematic structure of the headlamp which concerns on another this embodiment of this invention. It is a graph which shows the relationship between the internal and external quantum efficiency of SCASN fluorescent substance, and heat processing temperature. It is a graph which shows the absorption factor of the light of a different wavelength of the fluorescent substance after performing heat processing. It is a figure which shows schematic structure of the headlamp which concerns on this embodiment. It is a figure which shows the emission spectrum at the time of using Ca (alpha) -SiAlON: Ce and Ca (alpha) -SiAlON: Eu as fluorescent substance. It is a figure which shows schematic structure of the headlamp which concerns on another embodiment of this invention. It is a figure which shows the emission spectrum at the time of using (beta) -SiAlON: Eu and CASN: Eu as fluorescent substance. It is sectional drawing of the ceiling in which the laser downlight which concerns on one Embodiment of this invention was installed. It is sectional drawing of the said laser downlight. It is sectional drawing which shows the example of a change of the installation method of the said laser downlight.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS. Here, a headlamp (vehicle headlamp) 1 that satisfies the light distribution characteristic standard of a traveling headlamp (high beam) for automobiles will be described as an example of the lighting device of the present invention. However, the lighting device of the present invention may be realized as a headlamp of a vehicle other than an automobile or a moving object (for example, a human, a ship, an aircraft, a submersible craft, a rocket), or may be realized as another lighting device. Also good. Examples of other lighting devices include a searchlight, a projector, and a home lighting device.

<Configuration of headlamp 1>
First, the configuration of the headlamp 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a schematic configuration of a headlamp 1 according to the present embodiment. As shown in the figure, the headlamp 1 includes a semiconductor laser 2, an aspheric lens 3, a light guide unit 4, a light emitting unit 5, a reflecting mirror 6, and a transparent plate 7. The basic structure of the light emitting device is formed by the semiconductor laser 2, the light guide portion 4 and the light emitting portion 5.

(Semiconductor laser 2)
The semiconductor laser 2 functions as an excitation light source that emits excitation light. One or more semiconductor lasers 2 may be provided. Further, as the semiconductor laser 2, one having one light emitting point on one chip may be used, or one having a plurality of light emitting points may be used. In the present embodiment, one semiconductor laser 2 having one light emitting point per chip is used.

  The semiconductor laser 2 has, for example, one light emitting point (one stripe) per chip, oscillates a 405 nm (blue-violet) laser beam, an optical output of 1.0 W, an operating voltage of 5 V, and a current of 0.1. 7A and enclosed in a package (stem) having a diameter of 5.6 mm. The laser light oscillated by the semiconductor laser 2 is not limited to 405 nm, and may be any laser light having a peak wavelength in a wavelength range of 380 nm to 470 nm.

  If a high-quality short-wavelength semiconductor laser that oscillates laser light having a wavelength smaller than 380 nm can be manufactured, laser light having a wavelength smaller than 380 nm is oscillated as the semiconductor laser 2 of the present embodiment. It is also possible to use a semiconductor laser designed as described above.

The light output of the semiconductor laser 2 is 1 W or more and 20 W or less, and the light density (irradiation density) of the laser light applied to the light emitting unit 5 is preferably 0.1 W / mm ² or more and 50 W / mm ² or less. . If the light output is within this range, it is possible to achieve the luminous flux and brightness required for the vehicle headlamp, and it is possible to prevent the light emitting section 5 from being extremely deteriorated by the laser light having a high output. That is, it is possible to realize a light source having a long lifetime while having a high luminous flux and a high luminance.

  The aspherical lens 3 is a lens for causing the laser light oscillated from each semiconductor laser 2 to enter the light incident surface 4 a that is one end of the light guide 4. For example, as the aspherical lens 3, FLKN1 405 manufactured by Alps Electric can be used. The shape and material of the aspherical lens 3 are not particularly limited as long as the lens has the above-described function. However, it is preferable that the aspherical lens 3 is a material having a high transmittance near 405 nm and good heat resistance.

(Light guide 4)
The light guide unit 4 is a truncated cone-shaped light guide member that condenses the laser light oscillated by the semiconductor laser 2 and guides it to the light emitting unit 5 (the laser light irradiation surface of the light emitting unit 5). And is optically coupled to the semiconductor laser 2. The light guide 4 includes a light incident surface 4a (incident end) that receives the laser light emitted from the semiconductor laser 2 and a light emission surface 4b (emitted) that emits the laser light received at the light incident surface 4a to the light emitting unit 5. End).

  The area of the light emitting surface 4b is smaller than the area of the light incident surface 4a. Therefore, each laser beam incident from the light incident surface 4a is converged and emitted from the light emitting surface 4b by moving forward while being reflected on the side surface of the light guide unit 4.

  The light guide unit 4 is made of quartz glass, acrylic resin, or other transparent material. Further, the light incident surface 4a and the light emitting surface 4b may be planar or curved.

  The coupling efficiency of the aspherical lens 3 and the light guide 4 (ratio of the intensity of the laser light emitted from the light exit surface 4b of the light guide 4 to the intensity of the laser light emitted from the semiconductor laser 2) is 90%. is there. For this reason, 12 W laser light emitted from the semiconductor laser 2 is emitted as 10.8 W laser light from the light emitting surface 4 b after passing through the aspherical lens 3 and the light guide 4.

  The light guide 4 may be in the shape of a truncated pyramid as described later, or may be an optical fiber, as long as it guides the laser light from the semiconductor laser 2 to the light emitting part 5. Further, the light emitting unit 5 may be irradiated with the laser light from the semiconductor laser 2 through the aspherical lens 3 or directly without providing the light guide unit 4. Such a configuration is possible when the distance between the semiconductor laser 2 and the light emitting unit 5 is short.

(Light emitting part 5)
The light emitting unit 5 emits light by receiving laser light emitted from the light emitting surface 4b of the light guide unit 4, and a heat resistant phosphor that emits light by receiving laser light (hereinafter simply referred to as phosphor). It is dispersed in a heat resistant transparent sealing material (hereinafter simply referred to as a sealing material).

  The phosphor is, for example, an oxynitride phosphor or a semiconductor nanoparticle phosphor using nanometer-sized particles of a III-V compound semiconductor, and blue, green, and red phosphors are converted into low-melting glass. Is distributed. Since the semiconductor laser 2 oscillates 405 nm (blue-violet) laser light, white light is generated when the light emitting unit 5 is irradiated with the laser light. Therefore, it can be said that the light emitting unit 5 is a wavelength conversion member. Details of the composition of the light emitting section 5 will be described later.

  The semiconductor laser 2 may oscillate 450 nm (blue) laser light (or laser light in the vicinity of so-called “blue” having a peak wavelength in the wavelength range of 440 nm to 490 nm). The phosphor is a yellow phosphor or a mixture of a green phosphor and a red phosphor. A yellow phosphor is a phosphor that emits light having a peak wavelength in a wavelength range of 560 nm to 590 nm. The green phosphor is a phosphor that emits light having a peak wavelength in a wavelength range of 510 nm or more and 560 nm or less. The red phosphor is a phosphor that emits light having a peak wavelength in a wavelength range of 600 nm to 680 nm.

  The light emitting unit 5 is fixed to the focal position of the reflecting mirror 6 or in the vicinity thereof on the inner surface of the transparent plate 7 (the side on which the light emitting surface 4b is located). The method for fixing the position of the light emitting unit 5 is not limited to this method, and the position of the light emitting unit 5 may be fixed by a rod-like or cylindrical member extending from the reflecting mirror 6.

The shape of the light emitting unit 5 is not particularly limited, and may be a rectangular parallelepiped or a cylindrical shape. In the present embodiment, the light emitting unit 5 has a cylindrical shape with a diameter of 3.5 mm and a thickness of 2 mm. In this case, the area of the laser light irradiation surface that receives the laser light from the semiconductor laser 2 and the surface facing the laser light irradiation surface is about 9.6 mm ² .

  Further, the thickness between the laser light irradiation surface and the light emitting surface of the light emitting unit 5 may not be 2 mm. The thickness may be any thickness as long as the laser light is converted into white light in the light emitting unit 5 or the laser light is sufficiently scattered in the light emitting unit 5. That is, it is only necessary that the light emitting unit 5 has a thickness sufficient to convert all coherent light harmful to the human body into harmless incoherent light.

  The required thickness of the light emitting unit 5 varies according to the ratio between the sealing material and the phosphor in the light emitting unit 5. If the phosphor content in the light emitting unit 5 is increased, the efficiency of conversion of laser light into white light is increased, so that the thickness of the light emitting unit 5 can be reduced.

(Reflector 6)
The reflecting mirror 6 reflects incoherent light (hereinafter simply referred to as “light”) emitted from the light emitting unit 5 to form a light bundle that travels within a predetermined solid angle. That is, the reflecting mirror 6 reflects the light from the light emitting unit 5 to form a light beam that travels forward of the headlamp 1. The reflecting mirror 6 is, for example, a curved (cup-shaped) member having a metal thin film formed on the surface thereof, and opens in the traveling direction of reflected light.

(Transparent plate 7)
The transparent plate 7 is a transparent resin plate that covers the opening of the reflecting mirror 6 and holds the light emitting unit 5. The transparent plate 7 is preferably formed of a material that blocks the laser light from the semiconductor laser 2 and transmits white light (incoherent light) generated by converting the laser light in the light emitting unit 5. In addition to the resin plate, an inorganic glass plate or the like can be used as the transparent plate 7.

  Most of the coherent laser light is converted into incoherent white light by the light emitting unit 5. However, there may be a case where a part of the laser beam is not converted for some reason. Even in such a case, the laser beam can be prevented from leaking to the outside by blocking the laser beam with the transparent plate 7. Note that the transparent plate 7 can be omitted when the light emitting unit 5 is held by a member other than the transparent plate 7 without expecting such an effect.

<Composition of light-emitting part 5>
The inventors of the present invention have found that when the light emitting portion is excited with high power laser light, the light emitting portion is severely deteriorated. The deterioration of the light emitting part is mainly caused by the deterioration of the phosphor itself contained in the light emitting part and the deterioration of the sealing material surrounding the phosphor. For example, a sialon phosphor generates light with an efficiency of 60 to 80% when irradiated with laser light, but the rest is emitted as heat. It is considered that the sealing material deteriorates due to this heat.

  Therefore, appropriately selecting the sealing material and the phosphor material is very important for extending the life of the light emitting section. From such a point of view, the light emitting section 5 has a phosphor dispersed in a glass material as a sealing material. By making the sealing material into a glass material, it is possible to prevent the sealing material from being significantly deteriorated by heat generated when the phosphor is excited.

(Encapsulant material and mixing ratio)
As the sealing material, inorganic glass or so-called organic-inorganic hybrid glass can be used, and low melting point glass is particularly preferable. The low melting point glass preferably has a glass transition point of 600 ° C. or lower, and preferably contains at least one of SiO ₂ , B ₂ O ₃ , and ZnO. By adding SiO ₂ , B ₂ O ₃ , or ZnO, the glass transition point and the firing temperature can be lowered and the transparency can be maintained while stabilizing the low-melting glass.

When a low melting point glass is used as the sealing material, the volume ratio is preferably 1: 1000 or more and 1: 1 or less when the mixing ratio of the phosphor and the low melting point glass is expressed as a volume ratio. Here, the above-mentioned phosphor refers to the total amount of phosphors mixed to make white. As for the low-melting glass, a density of approximately ^{3g / cm 3 ~7g / cm 3} . When the mixing ratio of the phosphor and the low melting point glass is expressed as a mass ratio, the range of the mass ratio (phosphor: low melting point glass) is preferably 0.5: 100 or more and 20: 100 or less.

As the low melting point glass, a glass material having a low melting point by adding CaO—BaO—Li ₂ O—Na ₂ O to borosilicate glass (SiO ₂ —B ₂ O ₃ ) is used. This glass material is not highly reactive with the phosphor material. Similarly, if the glass has a low melting point and a low reaction with the phosphor material, almost the same result is considered to be obtained. On the other hand, in the case of a glass material that reacts with the phosphor, the luminous efficiency of the phosphor may be reduced simply by firing to form a light emitting part.

  Moreover, when the organic-inorganic hybrid glass is used as the sealing material, the preferable mass ratio (phosphor: hybrid glass) range between the phosphor and the organic-inorganic hybrid glass is 5.13: 200 or more and 50: 200 or less. It is preferable.

  The above numerical range is calculated by the inventors through experiments. In this experiment, the luminous efficiency was calculated for each of the samples having different mixing ratios (after firing), and the range of the mixing ratio that can realize the luminous efficiency that can withstand practicality was specified. Since the specific gravity is different between the hybrid glass and the glass material, a preferable range of the mixing ratio is calculated separately.

  When using a low-melting glass as the sealing material, the phosphor can be dispersed evenly in the produced light-emitting portion 5 if the mass ratio of the phosphor to the low-melting glass is 0.5: 100 or more. . When the phosphor concentration is lower than 0.5: 100, most of the excitation light passes through the light emitting unit 5 as it is, and sufficient illumination light cannot be obtained. Therefore, the mass ratio is preferably 0.5: 100 or more.

  In addition, when implement | achieving the illuminating device of this invention as a transmissive | pervious laser lighting fixture, it is more preferable that the said mass ratio is 1.0: 100 or more. If the ratio is 1.0: 100 or more, the laser light used as excitation light can be scattered by the phosphor particles to reduce the coherency.

  On the other hand, if the phosphor concentration is higher than 20: 100, the surface of the light-emitting portion 5 is rough and very brittle, so that part of the light-emitting portion 5 is likely to be lost due to physical contact or the like. Therefore, the mass ratio is preferably 20: 100 or less.

  If the mass ratio is in the vicinity of 20: 100 (however, it does not exceed 20: 100), the surface of the produced light-emitting part 5 is considerably exposed and the flatness is lowered. There is no problem to use as. If flatness of the light emitting portion surface is required, the mass ratio is preferably 15: 100 or less.

  Moreover, when it produces in the range of 1.0: 100 or more and 15: 100 or less, for example, 3: 100, 5: 100, 7: 100 etc., the light emission part 5 without a problem, such as a dispersibility, a nonuniformity, and a surface state, is produced. Can do. Therefore, if it is manufactured in this range (1: 100 to 15: 100) according to the desired color temperature and chromaticity, a light emitting part with high efficiency and excellent shape reproducibility can be realized with high yield. .

  The dispersion ratio between the phosphor and the sealing material affects the heat generation efficiency of the light emitting part (in other words, the heat dissipation efficiency). If the phosphor is 100%, the heat generation of the light emitting portion is increased, and the light emitting portion is rapidly deteriorated. Heat generation of the phosphor can be suppressed by sealing the light emitting portion with an appropriate amount of sealing material.

  Thus, the light emission efficiency and heat resistance of the light emission part 5 can be improved by setting appropriately the mixture ratio of fluorescent substance and a sealing material.

(Material of phosphor)
As the phosphor used in the light emitting section 5, what is commonly called an oxynitride phosphor is preferable. For example, a SiAlON phosphor, which is a typical oxynitride phosphor, is a substance in which some silicon atoms in silicon nitride are replaced with aluminum atoms and some nitrogen atoms are replaced with oxygen atoms. It can be made by dissolving alumina (Al ₂ O ₃ ), silica (SiO ₂ ), rare earth elements and the like in silicon nitride (Si ₃ N ₄ ).

Examples of the nitride phosphor include CASN (CaAlSiN ₃ ) phosphor and SCASN ((Sr, Ca) AlSiN ₃ ) phosphor. As will be described later, the SCASN phosphor is inferior to the CASN phosphor in heat resistance, but has a feature that the emission peak wavelength is shorter.

Emitting unit 5 is, for example, SiO ₂ and _B 2 _{O 3} and a ZnO 2: 2: low melting point glass and Caα-SiAlON in a proportion of 1: Ce and CASN: Eu as a weight ratio of 10: 2: 1 Is a mixture of

  As another suitable example of the phosphor, a semiconductor nanoparticle phosphor using nanometer-sized particles of a III-V compound semiconductor can be exemplified.

  One of the features of semiconductor nanoparticle phosphors is that even if the same compound semiconductor (for example, indium phosphorus: InP) is used, the emission color is changed by the quantum size effect by changing the particle diameter to nanometer size. It is a point that can be. For example, InP emits red light when the particle size is about 3 to 4 nm (here, the particle size was evaluated with a transmission electron microscope (TEM)).

  In addition, since this semiconductor nanoparticle phosphor is semiconductor-based, it has a short fluorescence lifetime and can emit the excitation light power as fluorescence quickly, so that it is highly resistant to high-power excitation light. This is because the emission lifetime of the semiconductor nanoparticle phosphor is about 10 nanoseconds, which is five orders of magnitude smaller than that of a normal phosphor material having a rare earth as the emission center.

  Furthermore, as described above, since the emission lifetime is short, the absorption of the laser beam and the emission of the phosphor can be quickly repeated. As a result, high efficiency can be maintained with respect to strong laser light, and heat generation from the phosphor can be reduced.

  Therefore, it is possible to further suppress deterioration (discoloration or deformation) of the light emitting unit 5 due to heat. Thereby, when using the light emitting element with a high light output as a light source, it can suppress more that the lifetime of a light-emitting device becomes short.

<Structure of semiconductor laser 2>
Next, the basic structure of the semiconductor laser 2 will be described. FIG. 2A schematically shows a circuit diagram of the semiconductor laser 2, and FIG. 2B is a perspective view showing the basic structure of the semiconductor laser 2. As shown in the figure, the semiconductor laser 2 has a configuration in which a cathode electrode 19, a substrate 18, a cladding layer 113, an active layer 111, a cladding layer 112, and an anode electrode 17 are laminated in this order.

The substrate 18 is a semiconductor substrate, and it is preferable to use GaN, sapphire, or SiC in order to obtain blue to ultraviolet excitation light for exciting the phosphor as in the present application. In general, as other examples of a substrate for a semiconductor laser, a group IV semiconductor represented by a group IV semiconductor such as Si, Ge and SiC, GaAs, GaP, InP, AlAs, GaN, InN, InSb, GaSb and AlN Group V compound semiconductors, Group II-VI compound semiconductors such as ZnTe, ZeSe, ZnS and ZnO, oxide insulators such as ZnO, Al ₂ O ₃ , SiO ₂ , TiO ₂ , CrO ₂ and CeO ₂ , and SiN Any material of the nitride insulator is used.

  The anode electrode 17 is for injecting current into the active layer 111 through the cladding layer 112.

  The cathode electrode 19 is for injecting current into the active layer 111 from the lower part of the substrate 18 through the clad layer 113. The current is injected by applying a forward bias to the anode electrode 17 and the cathode electrode 19.

  The active layer 111 has a structure sandwiched between the clad layer 113 and the clad layer 112.

  As a material for the active layer 111 and the cladding layer 113, a mixed crystal semiconductor made of AlInGaN is used to obtain blue to ultraviolet excitation light. Generally, a mixed crystal semiconductor mainly composed of Al, Ga, In, As, P, N, and Sb is used as an active layer / cladding layer of a semiconductor laser, and such a configuration may be used. The active layer 111 and the cladding layer 113 may be made of a II-VI group compound semiconductor such as Zn, Mg, S, Se, Te, and ZnO.

  The active layer 111 is a region where light emission is caused by the injected current, and the emitted light is confined in the active layer 111 due to a difference in refractive index between the cladding layer 112 and the cladding layer 113.

  Further, the active layer 111 is formed with a front side cleaved surface 114 and a back side cleaved surface 115 provided to face each other in order to confine light amplified by stimulated emission, and the front side cleaved surface 114 and the back side cleaved surface 115. Plays the role of a mirror.

  However, unlike a mirror that completely reflects light, a part of the light amplified by stimulated emission is obtained by cleaving the front side cleaved surface 114 and the back side cleaved surface 115 of the active layer 111 (in this embodiment, the front side cleaved surface 114 for convenience. And the excitation light L0. Note that the active layer 111 may form a multilayer quantum well structure.

  Note that a reflective film (not shown) for laser oscillation is formed on the back side cleaved surface 115 opposite to the front side cleaved surface 114, and the difference in reflectance between the front side cleaved surface 114 and the back side cleaved surface 115 is different. By providing, for example, most of the excitation light L0 can be irradiated from the light emitting point 103 from the cleaved surface 114 which is a low reflectance end face, for example.

  The clad layer 113 and the clad layer 112 are made of n-type and p-type GaAs, GaP, InP, AlAs, GaN, InN, InSb, GaSb, and AlN group III-V compound semiconductors, and ZnTe, ZeSe. , ZnS, ZnO, and other II-VI group compound semiconductors, and by applying a forward bias to the anode electrode 17 and the cathode electrode 19, current can be injected into the active layer 111. It has become.

  As for film formation with each semiconductor layer such as the clad layer 113, the clad layer 112, and the active layer 111, MOCVD (metal organic chemical vapor deposition) method, MBE (molecular beam epitaxy) method, CVD (chemical vapor deposition) method. The film can be formed using a general film forming method such as a laser ablation method or a sputtering method. The film formation of each metal layer can be configured using a general film forming method such as a vacuum deposition method, a plating method, a laser ablation method, or a sputtering method.

<Light emission principle of light emitting unit 5>
Next, the light emission principle of the phosphor by the laser light oscillated from the semiconductor laser 2 will be described.

  First, the laser light oscillated from the semiconductor laser 2 is irradiated onto the phosphor included in the light emitting unit 5, whereby electrons existing in the phosphor are excited from a low energy state to a high energy state (excited state).

  Since this excited state is unstable, the energy state of the electrons in the phosphor is changed to the original low energy state after a certain time (the energy state of the ground level or the level between the excited level and the ground level). Transition to a stable level energy state).

  In this way, the phosphors emit light when electrons excited to the high energy state transition to the low energy state.

  White light can be composed of a mixture of three colors that satisfy the principle of equal colors, or a mixture of two colors that satisfy the relationship of complementary colors, and based on this principle and relationship, the color and fluorescence of laser light oscillated from a semiconductor laser. White light can be generated by combining the color of light emitted by the body as described above.

<Experimental example 1>
The experimental result regarding the spectrum of the light emitted from the light emitting unit 5 will be described.

(Emission spectrum)
FIG. 3 is a diagram showing an emission spectrum when Caα-SiAlON: Ce and CASN: Eu are used as phosphors. The horizontal axis of the graph indicates the wavelength of light emitted from the phosphor, and the vertical axis indicates the intensity of the light.

As a sealing material of a light-emitting portion 5, ZnO and SiO ₂ and _B 2 _{O 3} 2: 2: using a low-melting glass in a proportion of 1. The low melting point glass, Caα-SiAlON: Ce and CASN: Eu are mixed at a weight ratio of 30: 3: 1 and heated and dissolved to form a light emitting section 5 having a cylindrical shape (diameter 3.5 mm, thickness 2 mm). Formed.

A laser beam with an output of 1 W emitted from the semiconductor laser 2 was formed into a conical beam having a diameter of 3.5 mm using the aspherical lens 3 and irradiated to the light emitting unit 5. The irradiation light density is 0.1 W / mm ² . In this experiment, the light guide 4 is not used.

  When the emission spectrum was measured, a spectrum having a peak at about 507 nm was obtained for Caα-SiAlON: Ce. In addition, a spectrum having a peak at about 650 nm was obtained for CASN: Eu.

  In the low melting point glass of this embodiment, the glass transition point and the firing temperature can be lowered and the transparency can be maintained while stabilizing the glass by adding ZnO to the borosilicate glass.

By dispersing the SiAlON phosphor, which is an oxynitride phosphor, and the CASN phosphor, which is a nitride phosphor, in the above-described sealing material, a phosphor light emitting portion that is not easily deteriorated even by laser light excitation can be realized. .

<Experimental example 2>
Next, the experiment regarding the heat resistance of the light emitting part 5 formed by dispersing the SCASN phosphor in the glass material will be described.

SCASN phosphor is a phosphor containing more Sr (strontium) in the CASN phosphor, which is a type of nitride compound phosphor. This SCASN phosphor is considered to be inferior to the CASN phosphor in terms of heat resistance due to the influence of Sr. Incidentally, the SiAlON phosphor is considered to be crystallinely stronger than the CASN phosphor and higher in heat resistance than the CASN phosphor.

  Therefore, regarding heat resistance, a relationship of SiAlON phosphor> CASN phosphor> SCASN phosphor is established. Therefore, it is considered that SiAlON phosphors and CASN phosphors can withstand temperatures that can withstand SCASN phosphors.

(experimental method)
The SCASN phosphor was heated up to a predetermined temperature in the atmosphere in 30 minutes, heated at that temperature for 30 minutes, and then the internal and external quantum efficiencies and absorption rates were measured at room temperature. Such an experiment was performed several times with different heat treatment temperatures. The results are shown in FIG. 4 and FIG.

  FIG. 4 is a graph showing the relationship between the internal and external quantum efficiencies of the SCASN phosphor and the heat treatment temperature. The vertical axis of the graph indicates the quantum efficiency, and the horizontal axis of the graph indicates the processing temperature when the SCASN phosphor is heat-treated. A solid line graph indicates a change in internal quantum efficiency, and a broken line graph indicates a change in external quantum efficiency.

  As shown in FIG. 4, the experimental results at 0 ° C. show the internal and external quantum efficiencies of the SCASN phosphor without heat treatment, and the internal and external quantum efficiencies are up to a heat treatment temperature of about 560 ° C. There was no effect of heat treatment. However, the internal and external quantum efficiencies decreased significantly as the heat treatment temperature further increased.

  From this fact, even when the heat-resistant phosphor used in the present invention is subjected to a heat treatment in a temperature range of at least 0 ° C. to 560 ° C., the quantum efficiency measured at a temperature after the heat treatment is It can be said that the quantum efficiency previously measured at a certain temperature does not drop beyond the error range.

  FIG. 5 is a graph showing the absorptance of light having different wavelengths of the phosphor after the heat treatment. As shown in FIG. 5, the light absorptance of light of different wavelengths of the SCASN phosphor is not greatly different from the light absorptivity at room temperature (no heat treatment) up to a heat treatment temperature of 600 ° C., A remarkable change was observed at least when the heat treatment temperature was 700 ° C. or higher. Specifically, when the heat treatment temperature is 700 ° C. or 800 ° C., the light absorption rate is clearly different from that in the case where heat treatment is performed at a temperature lower than those, and it can be seen that the phosphor has deteriorated. .

  From these experimental results, it was found that the heat-resistant temperature of the SCASN phosphor in the atmosphere is less than 600 ° C. The cause of the deterioration of the SCASN phosphor is considered to be that nitrogen contained in the SCASN phosphor is lost. Therefore, if heat treatment is performed in nitrogen, nitrogen desorption of the SCASN phosphor can be suppressed, and a decrease in light emission efficiency may be suppressed.

  For example, in the headlamp 1, the space formed by the reflecting mirror 6 and the transparent plate 7 is filled with nitrogen gas, and the light-emitting unit 5 is irradiated with laser light in the nitrogen gas to increase the heat resistance of the light-emitting unit 5. May be possible.

<Effect of headlamp 1>
As described above, the headlamp 1 can prevent deterioration of the light emitting unit 5 without reducing the luminous flux of the light emitted from the light emitting unit 5, achieves the luminance required for the headlamp, and achieves a long-life head. The lamp 1 can be realized. Further, since the light emitting unit 5 has a long life, the labor and cost for replacing the light emitting unit 5 can be reduced.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIGS. In addition, about the member similar to Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  FIG. 6 is a diagram showing a schematic configuration of the headlamp 20 according to the present embodiment. As shown in the figure, unlike the headlamp 1, the headlamp 20 includes an aspherical lens 31 that is a rod lens, a light guide portion 41, and a light emitting portion 51.

  The light guide unit 41 is a truncated pyramid-shaped light guide member that receives the laser light oscillated from the semiconductor laser 2 at the light incident surface 41 a and guides the laser light to the light emitting unit 51 by being emitted from the light emitting surface 41 b. Yes, it is optically coupled to the semiconductor laser 2 via an aspheric lens 31. The light guide part 41 is the same as the light guide part 4 only in the shape and the light guide part 4. The light guide 41 may be omitted in the same manner as the light guide 4.

  The light emitting unit 51 is a rectangular parallelepiped having a length of 1.2 mm, a width of 0.4 mm, and a depth of 0.5 mm. The shape of the light emitting unit 51 is different from that of the light emitting unit 5. The light distribution pattern (light distribution) of a vehicle headlamp that is legally regulated in Japan is narrow in the vertical direction and wide in the horizontal direction. By making the cross section substantially rectangular), the light distribution pattern can be easily realized.

In the present embodiment, the light emitting unit 51 uses Caα-SiAlON: Ce and Caα-SiAlON: Eu as phosphors, and the fluorescence is applied to low-melting glass in which BaO is added based on SiO ₂ , B ₂ O ₃ and ZnO. The body is dispersed. Addition of BaO to the low-melting glass can improve the stability of the glass such as chemical durability and non-crystallization.

  In the present embodiment, the semiconductor laser 2 is of 10 stripes per chip (10 light emitting points per chip), the oscillation wavelength is 405 nm, the optical output is 10 W, the operating voltage is 5 V, the current is 6 A, The power consumption is 30 W, and it is mounted on a 9 mm diameter stem. One such semiconductor laser 2 is used.

<Experimental example 3>
The experimental results regarding the spectrum of the light emitted from the light emitting unit 51 will be described.

  FIG. 7 is a diagram showing an emission spectrum when Caα-SiAlON: Ce and Caα-SiAlON: Eu are used as phosphors. The horizontal axis of the graph indicates the wavelength of light emitted from the phosphor, and the vertical axis indicates the intensity of the light.

A low melting point glass containing SiO ₂ , B ₂ O ₃ and BaO at a ratio of 2: 2: 1 was used as the phosphor holding material. This low-melting glass, Caα-SiAlON: Ce and Caα-SiAlON: Eu are mixed at a weight ratio of 20: 1: 1, and heated to form a rectangular parallelepiped (length 1.2 mm × width 0.4 mm × depth 0). 0.5 mm) of light emitting part 51 was formed.

When the emission spectrum was measured, a spectrum having a peak at about 507 nm was obtained for Caα-SiAlON: Ce. In addition, a spectrum having a peak at about 585 nm was obtained for Caα-SiAlON: Eu .

Laser light (output 10 W) radiated from the semiconductor laser 2 is formed into, for example, a length of 1 mm × width of 0.2 mm by the aspheric lens 31 and excites the light emitting unit 51 with a light density of 50 W / mm ² . In this experiment, the light guide 41 is not used.

  In this embodiment, by using a very stable oxynitride phosphor, it is possible to realize a laser illumination light source that does not deteriorate the light emitting portion even when laser light excitation with high output and high light density is performed. I was able to.

[Embodiment 3]
The following will describe another embodiment of the present invention with reference to FIGS. In addition, about the member similar to Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  FIG. 8 is a diagram showing a schematic configuration of the headlamp 30 according to the present embodiment. As shown in the figure, unlike the headlamp 1, the headlamp 30 includes 20 semiconductor lasers 2, 20 aspherical lenses 3, a light guide part 42, a light emitting part 52, and an optical fiber fixture 8. Yes.

  The semiconductor laser 2 is the same as the semiconductor laser 2 of the first embodiment, has one light emitting point per chip, and has an optical output of 1.0 W. Therefore, a total of 20 W of light flux is emitted from the plurality of semiconductor lasers 2.

  The light guide unit 42 is a bundle of 20 optical fibers 42a, and is a light guide member that guides the laser light oscillated by the 20 semiconductor lasers 2 to the light emitting unit 52 by the optical fibers 42a. Note that the numbers of the semiconductor laser 2, the aspherical lens 3, and the optical fiber 42 a are not limited to 20 as long as they match.

  The optical fiber 42a has a two-layer structure in which a central core is covered with a clad having a refractive index lower than that of the core. The core is mainly composed of quartz glass (silicon oxide) having almost no absorption loss of laser light, and the clad is composed mainly of quartz glass or a synthetic resin material having a refractive index lower than that of the core. .

  For example, the optical fiber 42a is made of quartz having a core diameter of 200 μm, a cladding diameter of 240 μm, and a numerical aperture NA of 0.22, but the structure, thickness, and material of the optical fiber 42a are limited to those described above. Instead, the cross section perpendicular to the long axis direction of the optical fiber 42a may be rectangular.

  The aspherical lens 3 causes the laser light oscillated from the semiconductor laser 2 to enter an incident end that is one end of the optical fiber 42a.

The emission end, which is the other end of the optical fiber 42a, is bundled by the optical fiber fixture 8, and a light beam having a diameter of 5 mm is irradiated onto the light emitting unit 52. The light density at this time is 20 W / mm ² . The emission end portion of the optical fiber 42 a is positioned with respect to the light emitting portion 52 so that the laser light emitted from the emission end portion is irradiated to the light emitting portion 52.

The light emitting part 52 has a cylindrical shape with a diameter of 5.2 mm and a thickness of 1 mm. The light emitting unit 52 is obtained by dispersing β-SiAlON: Eu and CASN: Eu as phosphors in a SiO ₂ —B ₂ O ₃ -based low-melting glass containing PbO.

<Experimental example 4>
The experimental results regarding the spectrum of the light emitted from the light emitting unit 52 will be described.

  FIG. 9 is a diagram showing an emission spectrum when β-SiAlON: Eu and CASN: Eu are used as phosphors. The horizontal axis of the graph indicates the wavelength of light emitted from the phosphor, and the vertical axis indicates the intensity of the light.

As the sealing material, low melting point glass containing SiO ₂ , B ₂ O ₃ and PbO at a ratio of 2: 2: 1 was used. This low-melting glass, β-SiAlON: Eu, and CASN: Eu are mixed at a mass ratio of 50: 3: 1 and heated and melted by hot press molding to form a cylindrical shape (diameter 5.2 mm, thickness 1 mm). The light emitting part 5 was formed.

  When this light emitting portion 5 was irradiated with laser light, a spectrum with a peak at about 540 nm was obtained for β-SiAlON: Eu. In addition, a spectrum having a peak at about 650 nm was obtained for CASN: Eu.

Also in this example, it was possible to realize a phosphor light-emitting portion that has an output of 20 W, an optical density as high as 20 W / mm ² , and can withstand laser light excitation with a high optical density.

[Embodiment 4]
The following will describe another embodiment of the present invention with reference to FIGS. In addition, about the member similar to Embodiment 1-3, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  Here, the laser downlight 200 as an example of the illuminating device of this invention is demonstrated. The laser downlight 200 is an illuminating device installed on the ceiling of a structure such as a house or a vehicle, and uses fluorescence generated by irradiating the light emitting unit 5 with laser light emitted from the semiconductor laser 2 as illumination light. It is.

  Note that an illuminating device having the same configuration as that of the laser downlight 200 may be installed on the side wall or floor of the structure, and the installation location of the illuminating device is not particularly limited.

  FIG. 10 is a cross-sectional view of the ceiling where the laser downlight 200 is installed. FIG. 11 is a cross-sectional view of the laser downlight 200. As shown in FIGS. 10 to 11, the laser downlight 200 is embedded in the top plate 400 and emits illumination light, and an LD light source unit that supplies laser light to the light emitting unit 210 via the optical fiber 42. 220. The LD light source unit 220 is not installed on the ceiling, but is installed at a position where the user can easily touch it (for example, a side wall of a house). The position of the LD light source unit 220 can be freely determined in this way because the LD light source unit 220 and the light emitting unit 210 are connected by the optical fiber 42. The optical fiber 42 is disposed in the gap between the top plate 400 and the heat insulating material 401.

(Configuration of light emitting unit 210)
As shown in FIG. 11, the light emitting unit 210 includes a housing 211, an optical fiber 42, a light emitting unit 5, and a light transmitting plate 213.

  A recess 212 is formed in the housing 211, and the light emitting unit 5 is disposed on the bottom surface of the recess 212. A metal thin film is formed on the surface of the recess 212, and the recess 212 functions as a reflecting mirror.

  In addition, a passage 214 for passing the optical fiber 42 is formed in the housing 211, and the optical fiber 42 extends to the light emitting unit 5 through the passage 214. The positional relationship between the emission end portion 5a of the optical fiber 42 and the light emitting portion 5 is the same as described above.

  The translucent plate 213 is a transparent or translucent plate disposed so as to close the opening of the recess 212. The translucent plate 213 has a function similar to that of the transparent plate 9, and the fluorescence of the light emitting unit 5 is emitted as illumination light through the translucent plate 213. The translucent plate 213 may be removable from the housing 211 or may be omitted.

  In the downlight, unlike a headlamp, an ideal point light source is not required, and a level of one light emitting point is sufficient. Therefore, there are fewer restrictions on the shape, size, and arrangement of the light emitting unit 5 than in the case of a headlamp.

(Configuration of LD light source unit 220)
The LD light source unit 220 includes a semiconductor laser 2, an aspheric lens 3, and an optical fiber 42.

  The incident end 5b, which is one end of the optical fiber 42, is connected to the LD light source unit 220, and the laser light oscillated from the semiconductor laser 2 passes through the aspherical lens 3 and enters the incident end 5b of the optical fiber 42. Is incident on.

  Only one pair of the semiconductor laser 2 and the aspherical lens 3 is shown inside the LD light source unit 220 shown in FIG. 11, but when there are a plurality of light emitting units 210, the optical fibers 42 extending from the light emitting units 210 respectively. The bundle may be guided to one LD light source unit 220. In this case, a pair of a plurality of semiconductor lasers 2 and an aspheric lens 3 (or a pair of a plurality of semiconductor lasers 2 and one rod-shaped lens 32) is accommodated in one LD light source unit 220. The LD light source unit 220 functions as a central power supply box.

(Example of changing the installation method of the laser downlight 200)
FIG. 12 is a cross-sectional view showing a modified example of the installation method of the laser downlight 200. As shown in the figure, as a modified example of the installation method of the laser downlight 200, only a small hole 402 through the optical fiber 42 is opened in the top plate 400, and the laser downlight main body (light emitting unit) is utilized by taking advantage of the thin and light weight. 210) can be attached to the top plate 400 using a strong adhesive tape or the like. In this case, there are advantages that restrictions on installation of the laser downlight 200 are reduced, and that construction costs can be significantly reduced.

(Example of change)
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  A solid-state laser other than the semiconductor laser may be used as the excitation light source. However, it is preferable to use a semiconductor laser because the excitation light source can be reduced in size.

  The present invention can be applied to a light emitting device with high brightness and long life, particularly a headlamp for a vehicle or the like.

1 Headlamp (light emitting device, vehicle headlamp)
2 Semiconductor laser 5 Light emitting unit 20 Head lamp (light emitting device, vehicle headlamp)
30 Headlamp (light emitting device, vehicle headlamp)
51 Light Emitting Unit 52 Light Emitting Unit 200 Laser Downlight (Lighting Device)

Claims (7)

A semiconductor laser that emits laser light;
A light emitting unit that receives and emits laser light emitted from the semiconductor laser,
In the light emitting part, the heat resistant phosphor is dispersed in the heat resistant transparent sealing material ,
The heat-resistant transparent sealing material is a low melting glass obtained by adding CaO—BaO—Li ₂ O—Na ₂ O to SiO ₂ —B ₂ O ₃ ,
The mass ratio of the heat-resistant phosphor and the heat-resistant transparent sealing material in the light-emitting portion is 0.5: 100 or more and 20: 100 or less,
The light emitting device according to claim 1, wherein an irradiation density of the laser light applied to the light emitting unit is 0.1 W / mm ² or more and 50 W / mm ² or less . A semiconductor laser that emits laser light;
A light emitting unit that receives and emits laser light emitted from the semiconductor laser,
In the light emitting part, the heat resistant phosphor is dispersed in the heat resistant transparent sealing material ,
The heat resistant transparent sealing material is an organic-inorganic hybrid glass,
The mass ratio of the heat-resistant phosphor and the organic-inorganic hybrid glass in the light-emitting portion is 5.13: 200 or more and 50: 200 or less ,
The light emitting device according to claim 1, wherein an irradiation density of the laser light applied to the light emitting unit is 0.1 W / mm ² or more and 50 W / mm ² or less . Even if the heat-resistant phosphor is subjected to a heat treatment in a temperature range of at least 0 ° C. to 560 ° C., the quantum efficiency of the heat-resistant phosphor measured at a temperature after the heat treatment is 3. The light emitting device according to claim 1, wherein the light emitting device does not decrease beyond an error range than the quantum efficiency measured at a certain temperature. The heat-resistant phosphor is a nanoparticle phosphor made of an oxynitride phosphor, a nitride phosphor, or a group III-V compound semiconductor, according to any one of claims 1 to 3 . Light emitting device. The oxynitride phosphor includes Caα-SiAlON (silicon aluminum oxynitride): Ce phosphor, Caα-SiAlON: Eu phosphor, β-SiAlON: Eu phosphor,
The light-emitting device according to claim 4 , wherein the nitride phosphor includes a CASN: EU phosphor or a SCASN: Eu phosphor. Lighting apparatus comprising: a light-emitting device according to any one of claims 1 to 5. Vehicle headlamp, characterized in that it comprises a light-emitting device according to any one of claims 1 to 5.

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