JP5090549B2 - Sintered light emitter, light emitting device, lighting device, vehicle headlamp, and method for producing sintered light emitter - Google Patents

Description

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

  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.

  An example of a technique related to such a light emitting device is a lamp disclosed in Patent Document 1. In this lamp, a semiconductor laser is used as an excitation light source in order to realize a high-intensity light source. Since the laser light oscillated from the semiconductor laser is coherent light, the directivity is strong, and the laser light can be condensed and used as excitation light without waste. A light-emitting device using such a semiconductor laser as an excitation light source (referred to as an LD light-emitting device) can be suitably applied to a vehicle headlamp. By using a semiconductor laser as an excitation light source, a high-intensity light source that cannot be realized with an LED can be realized.

  When such a laser beam is used as excitation light, a minute light emitting part, that is, a light emitting part with a minute volume, is converted into fluorescence by a phosphor out of excitation light irradiated to the light emitting part and absorbed. The component that is converted into heat without any problem easily raises the temperature of the light emitting part, and as a result, the characteristics of the light emitting part are deteriorated or damaged by heat.

  In order to solve this problem, in the invention of Patent Document 2, a translucent plate-like heat conductive member thermally connected to a wavelength conversion member (corresponding to a light emitting portion) is provided, and wavelength conversion is performed by this heat conductive member. Reduces heat generation of members.

  In the invention of Patent Document 3, the wavelength conversion member is held by a cylindrical ferrule, and a wire-like heat conduction member is thermally connected to the ferrule to reduce heat generation of the wavelength conversion member.

  Further, in the invention of Patent Document 4, a heat radiating member having a flow path through which a coolant flows is provided on the side of the light conversion member (corresponding to the light emitting portion) where the semiconductor light emitting element is located, thereby cooling the light conversion member.

  Note that Patent Document 5 discloses a configuration in which a light-transmitting heat sink is thermally connected to the surface of a high-power LED chip as a light source to cool the high-power LED chip.

JP 2005-150041 A (released on June 9, 2005) JP 2007-27688 A (published February 1, 2007) JP 2007-335514 A (released on December 27, 2007) Japanese Patent Laying-Open No. 2005-294185 (released on October 20, 2005) Special table 2009-513003 publication (announced March 26, 2009)

  However, when the thermal conductivity of the light emitting unit itself is low, there is a problem in that the heat radiation effect of the light emitting unit is not so high even if a heat conductive member with high thermal conductivity is brought into contact with the light emitting unit. The inventor found out the result of earnest research.

  The present invention has been made in order to solve the above-mentioned problems, and its purpose is to reduce the thermal resistance of the light emitting part, and as a result, to efficiently radiate heat from the light emitting part. It is providing the apparatus, the illuminating device, the vehicle headlamp, and the manufacturing method of a sintered light-emitting body.

  In order to solve the above-described problem, a sintered light-emitting body according to the present invention is a sintered light-emitting body obtained by sintering a ceramic material and a phosphor that emits light by excitation light emitted from an excitation light source using a binder. It is characterized by providing.

  In the present invention, the light emitter is sintered using a binder with a ceramic material and a phosphor emitting light by excitation light emitted from an excitation light source (hereinafter, such a light emitter is referred to as a sintered light emitter). In some cases).

  Accordingly, since the thermal conductivity is improved due to the thermal conductivity of the ceramic material, the thermal resistance of the light emitter is reduced, and the heat radiation from the light emitting portion is efficiently performed. Further, since the heat radiation from the light emitting part is efficiently performed, it is possible to avoid a situation where the light emitting part is deteriorated or damaged by heat and the life of the light emitting part is shortened.

  Furthermore, the sintered light emitter according to the present invention also provides the following effects. That is, in the sintered light-emitting body according to the present invention, the ceramic material and the phosphor are sintered using the binder, so that a grain boundary is generated inside the sintered light-emitting body. Therefore, when laser light having a coherent component that is likely to damage human eyes is used as excitation light, the laser light is scattered by the grain boundary. And the safety | security of a light-emitting device provided with a sintered light-emitting body and its sintered light-emitting body can also be improved by expanding the magnitude | size of a light emission point.

  Furthermore, in the sintered luminescent material according to the present invention, the ceramic material may have a high thermal conductivity.

  The sintered luminescent material according to the present invention can further enhance the heat dissipation effect because the ceramic material has high thermal conductivity.

  Furthermore, in the sintered luminescent material according to the present invention, the ceramic material may include alumina or aluminum nitride.

  The sintered luminescent material according to the present invention can include a sintered luminescent material having transparency and high thermal conductivity when the ceramic material contains alumina or aluminum nitride.

  Furthermore, in the sintered light emitting body according to the present invention, the sintered light emitting body may be one obtained by injection molding and sintering a mixture of the ceramic material, the phosphor, and the binder.

  In the conventional technique for producing a light emitter by melting treatment, there is a problem in that the phosphor is not uniformly dispersed and the light emission efficiency of the light emitter is reduced.

  On the other hand, the phosphor is made by injection molding and sintering a mixture of a ceramic material, a phosphor, and a binder, so that the phosphor can be dispersed, whereby the phosphor emits light. The conventional problem that efficiency is lowered can be solved.

  Furthermore, in the sintered light emitting body according to the present invention, the ceramic material may have a translucent structure.

  In the sintered light-emitting body of the present invention, the luminous efficiency of the phosphor, that is, the light-emitting efficiency of the light-emitting body can be increased because the ceramic material has translucency.

  Furthermore, in the sintered luminescent material according to the present invention, the phosphor may be an oxynitride phosphor.

  An oxynitride phosphor is a stable material with excellent heat resistance and high luminous efficiency. Therefore, when the phosphor is an oxynitride phosphor, a light emitter having excellent heat resistance and high luminous efficiency can be realized.

  Furthermore, in the sintered luminescent material according to the present invention, the phosphor may be a nanoparticle phosphor.

  With the above-described configuration, the light emitting unit is translucent to the wavelength region of visible light and light in the vicinity thereof. Therefore, the radiation efficiency from the phosphor to the outside of the light emitter can be increased.

  Furthermore, the light-emitting device according to the present invention may be configured to include the excitation light source that emits the excitation light and the sintered light-emitting body according to any one of the above.

  With the above configuration, the light emitting device according to the present invention can realize various effects of the above-described sintered light emitting body.

  Furthermore, in the light emitting device according to the present invention, the excitation light may be laser light.

  Since the phosphor of the light emitting device according to the present invention is formed by sintering a ceramic material and a phosphor using a binder, a grain boundary is generated inside the sintered phosphor. For this reason, laser light having a coherent component that is likely to damage the human eye is scattered by the grain boundaries. And the safety | security of a light-emitting device can be improved by the magnitude | size of a light emission point expanding.

  Furthermore, the light emitting device according to the present invention may be configured to further include a heat conducting member that contacts the sintered light emitting body and dissipates heat of the sintered light emitting body to the outside.

  According to said structure, the heat dissipation efficiency of a light emission part can further be improved by the heat | fever of a light emission part moving to the heat conductive member contact | abutted to the said light emission part.

  Furthermore, the illumination device according to the present invention may be configured to include any one of the light emitting devices described above.

  Furthermore, the vehicle headlamp according to the present invention may be configured to include any of the light emitting devices described above.

  The light emitting device according to the present invention can be suitably applied to lighting devices, vehicle headlamps, and the like. Thereby, for example, when the light-emitting device according to the present invention is applied to a vehicle headlamp, a vehicle headlamp that reduces the thermal resistance of the light-emitting portion and, as a result, can efficiently dissipate the light-emitting portion is realized. can do.

  Furthermore, in the method for producing a sintered luminescent material according to the present invention, the method for producing a sintered luminescent material according to any one of the above, wherein the phosphor and the binder emit light by excitation light emitted from a ceramic material and an excitation light source. And a sintering step of sintering the mixture mixed by the mixing step.

  In the conventional technique for producing the luminous body by a melting process, there is a problem that the luminous efficiency of the luminous body is lowered without the phosphor being uniformly dispersed.

  On the other hand, the phosphor is produced by the mixing process and the sintering process described above, whereby the phosphor can be dispersed, thereby reducing the luminous efficiency of the phosphor. Can be eliminated.

  As described above, the sintered luminescent material according to the present invention includes a sintered luminescent material obtained by sintering a ceramic material and a phosphor that emits light by excitation light emitted from an excitation light source using a binder. .

  Therefore, there is an effect that it is possible to provide a sintered light-emitting body that can reduce the thermal resistance of the light-emitting portion and, as a result, can efficiently dissipate the light-emitting portion.

It is a figure which shows the detail of the light emission part and heat conductive member which the headlamp which concerns on one Embodiment of this invention has. It is sectional drawing which shows the structure of the said headlamp. It is sectional drawing which shows the example of a change of the said light emission part. It is a conceptual diagram which shows the state which the fluorescent substance particle has disperse | distributed in the light emission part. (A) is a schematic diagram showing a circuit diagram of a semiconductor laser, and (b) is a perspective view showing a basic structure of the semiconductor laser. It is the schematic which shows the external appearance of the light emission unit with which the laser downlight which concerns on one Embodiment of this invention is equipped, and the conventional LED downlight. It is sectional drawing of the ceiling in which the said laser downlight 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. It is sectional drawing of the ceiling in which the said LED downlight was installed. It is a figure for comparing the specifications of the laser downlight and the LED downlight.

[Embodiment 1]
One embodiment of the present invention will be described below with reference to FIGS. Here, as an example of the illumination device of the present invention, an automotive headlamp (light emitting device, illumination device, vehicle headlamp) 1 will be described as an example. 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.

  Further, the headlamp 1 may satisfy the light distribution characteristic standard of the traveling headlamp (high beam), or may satisfy the light distribution characteristic standard of the passing headlamp (low beam).

(Configuration of headlamp 1)
First, the configuration of the headlamp 1 will be described with reference to FIG. FIG. 2 is a cross-sectional view showing the configuration of the headlamp 1. As shown in the figure, the headlamp 1 includes a semiconductor laser array 2, an aspherical lens 4, an optical fiber 5, a ferrule 6, a light emitting part (sintered light emitter) 7, a reflecting mirror 8, and a transparent plate. 9, a housing 10, an extension 11, a lens 12, a heat conducting member 13, and a cooling unit 14.

(Semiconductor laser array 2 / semiconductor laser 3)
The semiconductor laser array 2 functions as an excitation light source that emits excitation light, and includes a plurality of semiconductor lasers (excitation light sources) 3 on a substrate. Laser light as excitation light is oscillated from each of the semiconductor lasers 3. It is not always necessary to use a plurality of semiconductor lasers 3 as an excitation light source, and only one semiconductor laser 3 may be used. However, in order to obtain a high-power laser beam, it is preferable to use a plurality of semiconductor lasers 3. Easy.

  The semiconductor laser 3 has one light emitting point in one chip, for example, oscillates a laser beam of 405 nm (blue violet), has an output of 1.0 W, an operating voltage of 5 V, and a current of 0.6 A. It is enclosed in a package with a diameter of 5.6 mm. The laser beam oscillated by the semiconductor laser 3 is not limited to 405 nm, and any laser beam having a peak wavelength in another wavelength range may be used. Further, the package is not limited to the one having a diameter of 5.6 mm, and may be, for example, a diameter of 3.8 mm, a diameter of 9 mm, or other, and it is preferable to select a package having a smaller thermal resistance.

  In this embodiment, the semiconductor laser is used as the excitation light source. However, a light emitting diode can be used instead of the semiconductor laser.

(Aspherical lens 4)
The aspherical lens 4 is a lens for causing laser light (excitation light) oscillated from the semiconductor laser 3 to enter an incident end 5 b that is one end of the optical fiber 5. For example, as the aspheric lens 4, FLKN1 405 manufactured by Alps Electric can be used. The shape and material of the aspherical lens 4 are not particularly limited as long as the lens has the above function, but it is preferably a material having a high transmittance near 405 nm and a good heat resistance.

(Optical fiber 5)
(Disposition of optical fiber 5)
The optical fiber 5 is a light guide member that guides the laser light oscillated by the semiconductor laser 3 to the light emitting unit 7 and is a bundle of a plurality of optical fibers. The optical fiber 5 has a plurality of incident end portions 5b that receive the laser light and a plurality of emission end portions 5a that emit the laser light incident from the incident end portion 5b. The plurality of emission end portions 5 a emit laser beams to different regions on the laser beam irradiation surface 7 a of the light emitting unit 7.

  For example, the emission end portions 5a of the plurality of optical fibers 5 are arranged side by side in a plane parallel to the laser light irradiation surface 7a. With such an arrangement, the light intensity distribution in the light intensity distribution of the laser light emitted from the emission end portion 5a is the highest (the central portion of the irradiation region (the maximum light intensity portion formed by each laser light on the laser light irradiation surface 7a). )) Is emitted to different portions of the laser light irradiation surface 7a of the light emitting portion 7, and therefore, the laser light irradiation surface 7a of the light emitting portion 7 is irradiated in a two-dimensionally distributed manner. be able to.

  Therefore, it is possible to prevent a part of the light emitting unit 7 from being significantly deteriorated by locally irradiating the light emitting unit 7 with the laser light.

  The optical fiber 5 is not necessarily a bundle of a plurality of optical fibers (that is, a configuration including a plurality of emission end portions 5a), and may be a single optical fiber.

(Material and structure of optical fiber 5)
The optical fiber 5 has a two-layer structure in which an inner 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 5 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. However, the structure, thickness, and material of the optical fiber 5 are limited to those described above. Instead, the cross section perpendicular to the long axis direction of the optical fiber 5 may be rectangular.

  Moreover, since the optical fiber 5 has flexibility, the relative positional relationship between the semiconductor laser 3 and the light emitting unit 7 can be easily changed. Further, by adjusting the length of the optical fiber 5, the semiconductor laser 3 can be installed at a position away from the light emitting unit 7.

  Therefore, the degree of freedom in designing the headlamp 1 can be increased, for example, the semiconductor laser 3 can be installed at a position where it can be easily cooled or replaced.

  In addition, you may use what combined members other than an optical fiber, or an optical fiber and another member as a light guide member. For example, one or a plurality of light guide members having a truncated cone shape (or a truncated pyramid shape) having a laser beam incident end and an emission end may be used.

(Ferrule 6)
The ferrule 6 holds the plurality of emission end portions 5 a of the optical fiber 5 in a predetermined pattern with respect to the laser light irradiation surface of the light emitting unit 7. The ferrule 6 may be formed with holes for inserting the emission end portion 5a in a predetermined pattern, and can be separated into an upper part and a lower part, and is formed on the upper and lower joint surfaces, respectively. The exit end portion 5a may be sandwiched by a groove.

  The ferrule 6 may be fixed to the reflecting mirror 8 by a rod-like or cylindrical member extending from the reflecting mirror 8 or may be fixed to the heat conducting member 13. The material of the ferrule 6 is not specifically limited, For example, it is stainless steel. A plurality of ferrules 6 may be arranged for one light emitting unit 7.

  In addition, when the output end part 5a of the optical fiber 5 is one, the ferrule 6 can be omitted.

(Light Emitting Unit 7)
(Composition of light-emitting part 7)
FIG. 1 is a diagram showing details of the light emitting unit 7 and the heat conducting member 13. The light emitting unit 7 emits light upon receiving the laser light emitted from the emission end 5a. The light emitting portion 7 is formed by mixing ceramic materials, a binder, and phosphor particles 16, injection molding, and sintering the molded product. The phosphor particles 16 are uniformly dispersed inside the light emitting unit 7.

  The light emitting unit 7 includes one or more of phosphors that emit blue, green, and red light. Since the semiconductor laser 3 oscillates 405 nm (blue-violet) laser light, a plurality of colors are mixed and white light is generated when the light emitting unit 7 is irradiated with the laser light. Therefore, it can be said that the light emitting portion 7 is a wavelength conversion material.

  The semiconductor laser 3 may oscillate a 450 nm (blue) laser beam (or a so-called “blue” laser beam having a peak wavelength in a 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.

(Binder)
The binder is mixed with the ceramic material and the phosphor particles 16, and the mixture is sintered to bond the ceramic material and the phosphor particles 16. The material is not particularly limited, but it is important to select a material that decomposes at a relatively low temperature and does not leave residual ash or the like after decomposition, and acrylic resin, epoxy resin, silicon resin, or the like can be used. And a grain boundary can be generated in the light emission part 7 by sintering ceramic material and the fluorescent substance particle 16 using a binder. Details thereof will be described later.

(Phosphor)
The phosphor of the light emitting unit 7 is preferably an oxynitride phosphor or a III-V compound semiconductor nanoparticle phosphor. These materials are highly resistant to extremely strong laser light (output and light density) emitted from the semiconductor laser 3, and are optimal for a laser illumination light source. In addition, the nanoparticle phosphor has a particle size approximately two orders of magnitude smaller than the wavelength of light in the visible wavelength region.

As a typical oxynitride phosphor, there is a so-called sialon phosphor. A sialon phosphor is a substance in which part of silicon atoms in silicon nitride is replaced with aluminum atoms and part of nitrogen atoms is 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 ).

  On the other hand, one of the features of semiconductor nanoparticle phosphors is that even if the same compound semiconductor (for example, indium phosphorus: InP) is used, the particle size is changed within a certain range of the nanometer order, so that the quantum size effect is achieved. The point is that the emission color can be changed. 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.

  The material of the phosphor is not limited to the above-described oxynitride phosphor or III-V group compound semiconductor nanoparticle phosphor, and other materials can be used as appropriate.

(Shape and size of light-emitting part 7)
The shape and size of the light emitting unit 7 are, for example, a cylindrical shape having a diameter of 3.2 mm and a thickness of 1 mm, and the laser light emitted from the emission end 5a is applied to the laser light irradiation surface 7a that is the bottom surface of the cylinder. Receive light.

Moreover, the light emission part 7 may not be a column shape but a rectangular parallelepiped. For example, it is a rectangular parallelepiped of 3 mm × 1 mm × 1 mm. In this case, the area of the laser light irradiation surface that receives the laser light from the semiconductor laser 3 is 3 mm ² . 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.

  The required thickness of the light emitting unit 7 varies according to the ratio between the sealing material and the phosphor in the light emitting unit 7. If the phosphor content in the light emitting unit 7 is increased, the efficiency of conversion of laser light into white light is increased, so that the thickness of the light emitting unit 7 can be reduced. If the light emitting portion 7 is made thinner, the thermal resistance is reduced. However, if the light emitting portion 7 is made too thin, the laser light may not be converted into fluorescence and may be emitted to the outside. From the viewpoint of absorption of excitation light by the phosphor, the thickness of the light emitting part is preferably at least 10 times the particle size of the phosphor.

  For this reason, as thickness of the light emission part 7 using an oxynitride fluorescent substance, 0.2 mm or more and 2 mm or less are preferable. However, when the content of the phosphor is extremely increased (typically 100% of the phosphor), the lower limit of the thickness is not limited to this.

  From this point of view, the thickness of the light-emitting portion when using the nanoparticle phosphor should be 0.01 μm or more, but considering the ease of the manufacturing process such as dispersion in the sealing material, it is 10 μm or more. That is, 0.01 mm or more is preferable. On the other hand, if the thickness is too thick, a deviation from the focal point of the reflecting mirror 8 becomes large and the light distribution pattern is blurred.

  Further, the laser light irradiation surface 7a of the light emitting unit 7 is not necessarily a flat surface, and may be a curved surface. However, in order to control the reflected laser light, the laser light irradiation surface 7a preferably has a flat surface. When the laser light irradiation surface 7a is a curved surface, at least the incident angle to the curved surface changes greatly, so that the direction in which the reflected light travels greatly changes depending on the location where the laser light is irradiated. For this reason, it may be difficult to control the reflection direction of the laser light. On the other hand, if the laser light irradiation surface 7a is a flat surface, the traveling direction of the reflected light is hardly changed even if the irradiation position of the laser light is slightly shifted, so that the direction in which the laser light is reflected can be easily controlled. In some cases, it is easy to take measures such as placing a laser beam absorber in a place where the reflected light strikes.

  The laser light irradiation surface 7a is not necessarily perpendicular to the optical axis of the laser light. When the laser light irradiation surface 7a is perpendicular to the optical axis of the laser light, the reflected laser light returns in the direction of the laser light source, and in some cases, the laser light source may be damaged.

(Ceramic materials)
The ceramic material constituting the light emitting section 7 is preferably a material having high thermal conductivity and translucency.

One example of a ceramic material that satisfies such conditions is alumina. Alumina has a density of 3.8 g / cm ^{3 to} 3.9 g / cm ³ , a thermal conductivity of 15 W / mK to 40 W / mK, can be obtained at low cost, and is highly resistant to acids and alkalis, and has high reliability. This is suitable for producing the light emitting portion 7.

Other ceramic materials include aluminum nitride, magnesia, silicon nitride, silicon carbide and the like. Aluminum nitride has a density of 3.2 g / cm ^{3 to} 3.3 g / cm ³ and a thermal conductivity of 80 W / mK to 250 W / mK. Magnesia has a density of 3.5 g / cm ³ and a thermal conductivity of 48 W / mK. Silicon nitride has a density of 3.0 g / cm ^{3 to} 3.2 g / cm ³ and a thermal conductivity of 20 W / mK to 90 W / mK. Silicon carbide has a density of 3.0 g / cm ^{3 to} 3.2 g / cm ³ and a thermal conductivity of 60 W / mK to 180 W / mK. Thus, the ceramic material is not limited to the above-described alumina or the like, and various types can be used.

(Reflector 8)
The reflecting mirror 8 reflects the light emitted from the light emitting unit 7 to form a light beam that travels within a predetermined solid angle. That is, the reflecting mirror 8 reflects the light from the light emitting unit 7 to form a light beam that travels forward of the headlamp 1. The reflecting mirror 8 is, for example, a curved (cup-shaped) member having a metal thin film formed on the surface thereof.

(Transparent plate 9)
The transparent plate 9 is a transparent resin plate that covers the opening of the reflecting mirror 8. The transparent plate 9 is preferably formed of a material that blocks the laser light from the semiconductor laser 3 and transmits white light (incoherent light) generated by converting the laser light in the light emitting unit 7. . Most of the coherent laser light is converted into incoherent white light by the light emitting unit 7. 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 9.

  The transparent plate 9 may be used together with the heat conducting member 13 to fix the light emitting unit 7. That is, the light emitting unit 7 may be sandwiched between the heat conducting member 13 and the transparent plate 9. In this case, the transparent plate 9 functions as a fixing unit that fixes the relative positional relationship between the light emitting unit 7 and the heat conducting member 13.

  At this time, if the transparent plate 9 has a high thermal conductivity (for example, inorganic glass), the transparent plate 9 also functions as a heat conductive member, and the heat dissipation effect of the light emitting unit 7 can be obtained.

  In addition, when fixing the light emission part 7 only with the heat conductive member 13, the transparent plate 9 is also omissible.

(Housing 10)
The housing 10 forms the main body of the headlamp 1 and houses the reflecting mirror 8 and the like. The optical fiber 5 passes through the housing 10, and the semiconductor laser array 2 is installed outside the housing 10. The semiconductor laser array 2 generates heat when the laser light is oscillated, but the semiconductor laser array 2 can be efficiently cooled by being installed outside the housing 10. Therefore, deterioration of characteristics and thermal damage of the light emitting unit 7 due to heat generated from the semiconductor laser array 2 are prevented.

  Further, it is preferable to install the semiconductor laser 3 at a position where it can be easily replaced in consideration of a failure. If these points are not taken into consideration, the semiconductor laser array 2 may be accommodated in the housing 10.

(Extension 11)
The extension 11 is provided on the front side of the reflecting mirror 8 to hide the internal structure of the headlamp 1 to improve the appearance of the headlamp 1 and enhance the sense of unity between the reflecting mirror 8 and the vehicle body. Yes. The extension 11 is also a member having a metal thin film formed on the surface thereof, like the reflecting mirror 8.

(Lens 12)
The lens 12 is provided in the opening of the housing 10 and seals the headlamp 1. The light generated by the light emitting unit 7 and reflected by the reflecting mirror 8 is emitted to the front of the headlamp 1 through the lens 12.

(Heat conduction member 13)
The heat conducting member 13 is a translucent member that is disposed on the side of the laser light irradiation surface 7a that is the surface irradiated with the excitation light in the light emitting unit 7 and receives the heat of the light emitting unit 7. Connected (in other words, so that heat energy can be exchanged). The light emitting unit 7 and the heat conducting member 13 may be connected by an adhesive, for example.

  The heat conducting member 13 is a plate-like member, one end of which is in thermal contact with the laser light irradiation surface 7 a of the light emitting unit 7, and the other end is thermally connected to the cooling unit 14. Has been.

  The heat conducting member 13 has such a shape and connection form, and dissipates heat generated from the light emitting unit 7 to the outside of the headlamp 1 while holding the minute light emitting unit 7 at a specific position.

  In order to efficiently release the heat of the light emitting unit 7, the thermal conductivity of the heat conducting member 13 is preferably 20 W / mK or more. Further, the laser light emitted from the semiconductor laser 3 passes through the heat conducting member 13 and reaches the light emitting unit 7. Therefore, it is preferable that the heat conductive member 13 is made of a material having excellent translucency.

Considering these points, the material of the heat conducting member 13 is preferably sapphire (Al ₂ O ₃ ), magnesia (MgO), gallium nitride (GaN), or spinel (MgAl ₂ O ₄ ). By using these materials, a thermal conductivity of 20 W / mK or more can be realized.

  Further, the thickness of the heat conducting member 13 indicated by reference numeral 13c in FIG. 1 (a first surface 13a located on the laser light irradiation surface 7a side of the heat conducting member 13 and a second surface 13b facing the first surface 13a). Is preferably 0.3 mm or more and 3.0 mm or less. If the thickness is less than 0.3 mm, the light emitting unit 7 cannot sufficiently dissipate heat, and the light emitting unit 7 may be deteriorated. On the other hand, when the thickness exceeds 3.0 mm, the absorption of the irradiated laser light in the heat conducting member 13 is increased, and the utilization efficiency of the excitation light is significantly reduced.

  By bringing the heat conducting member 13 into contact with the light emitting portion 7 with an appropriate thickness, even when an extremely strong laser beam that emits more than 1 W is generated particularly in the light emitting portion 7, the heat generation is quick and efficient. It is possible to prevent heat emission and damage (deterioration) of the light emitting unit 7.

  In addition, the heat conductive member 13 may be a plate-shaped member that is not bent, or may have a bent part or a curved part. However, the portion to which the light emitting portion 7 is bonded is preferably flat (plate-shaped) from the viewpoint of adhesion stability.

Here, in order to enhance the heat absorption effect and heat dissipation effect of the heat conducting member 13, the following changes are effective.
-Increase the heat dissipation area (contact area with the light emitting part 7).
-Increase the thickness of the heat conducting member 13.
-Increase the thermal conductivity of the heat conducting member 13. For example, a material having high thermal conductivity is used. Alternatively, a member having a high thermal conductivity (such as a thin film or a plate member) is disposed on the surface of the heat conducting member 13.

  In addition, when forming a metal thin film etc. on the surface of the heat conductive member 13, a light beam may fall. In addition, when the surface of the heat conducting member 13 is covered or another member is disposed, the manufacturing cost increases.

(Modification example of heat conduction member 13)
The heat conductive member 13 may have a portion having a light transmitting property (light transmitting portion) and a portion having no light transmitting property (light shielding portion). In the case of this configuration, the light transmitting part is disposed so as to cover the laser light irradiation surface 7a of the light emitting part 7, and the light shielding part is disposed outside thereof.

  The light shielding part may be a heat radiating part of metal (for example, copper or aluminum), or aluminum, silver, or other film that has an effect of reflecting illumination light is formed on the surface of the translucent member. May be.

(Cooling unit 14)
The cooling unit 14 is a member that cools the heat conducting member 13, and is a heat radiating block having high thermal conductivity made of a metal such as aluminum or copper, for example. If the reflecting mirror 8 is made of metal, the reflecting mirror 8 may also serve as the cooling unit 14. Alternatively, the cooling unit 14 may be a cooling device that cools the heat conducting member 13 by circulating a cooling liquid therein, or a cooling device (fan) that cools the heat conducting member 13 by air cooling. May be.

  When the cooling unit 14 is realized as a metal lump, a plurality of heat radiation fins may be provided on the upper surface of the metal lump. With this configuration, the surface area of the metal lump can be increased, and heat dissipation from the metal lump can be performed more efficiently.

  The cooling unit 14 is not essential for the headlamp 1, and the heat received by the heat conducting member 13 from the light emitting unit 7 may be radiated from the heat conducting member 13 naturally. By providing the cooling unit 14, it is possible to efficiently dissipate heat from the heat conducting member 13. In particular, when the amount of heat generated from the light emitting unit 7 is 3 W or more, the installation of the cooling unit 14 is effective.

  Further, the cooling unit 14 can be installed at a position away from the light emitting unit 7 by adjusting the length of the heat conducting member 13. In this case, the cooling unit 14 is not limited to the configuration in which the cooling unit 14 is housed in the housing 10 as illustrated in FIG. 2, and the cooling unit 14 may be installed outside the housing 10 by the heat conducting member 13 passing through the housing 10. It becomes possible.

  Therefore, the cooling unit 14 can be installed at a position where it can be easily repaired or replaced in the event of a failure, and the design flexibility of the headlamp 1 can be increased.

(Modification example of the light emitting unit 7)
FIG. 3 is a cross-sectional view showing a modified example of the light emitting unit 7. As shown in FIG. 3, a heat conductive wall (heat conductive member) 18 that contacts the side surface of the light emitting unit 7 may be formed. The heat conductive wall 18 is a wall surface made of a material having translucency and high thermal conductivity, such as metal (for example, aluminum), sapphire, or inorganic glass.

  By providing the heat conducting wall 18 as the second heat conducting member together with the heat conducting member 13, the heat radiation effect of the light emitting portion 7 can be further enhanced.

(Manufacturing method of the light emitting part 7)
Next, a method for manufacturing the light emitting unit 7 will be described.

  First, each powder is weighed so that the ceramic material, the phosphor powder, and the binder are in a predetermined ratio, and mixed so that these powders are uniformly mixed (mixing step). This mixing process may be performed by putting each weighed powder in a container and manually rocking it, or by a mixing device.

  Here, as for the mixing ratio of mixing the ceramic material, the phosphor powder, and the binder, the ratio of the ceramic material + the phosphor and the binder is preferably 50:50 to 70:30. The phosphor concentration in the ceramic is preferably about 1:10 to 1: 2, although it varies depending on the target color temperature, chromaticity, efficiency of the phosphor used, and particle diameter. However, it is not limited to these mixing ratios, and may be appropriately determined.

  Here, FIG. 4 is a conceptual diagram showing a state in which the phosphor particles 16 are dispersed inside the light emitting unit 7, but when the phosphor concentration in the light emitting unit 7 is high, as shown in FIG. 4. It is preferable that the phosphor particles 16 are uniformly dispersed in the sealing material. This is because if the phosphor particles 16 are biased to one place, the amount of heat generated at that place increases, which may cause a reduction in light emission efficiency and deterioration of the light emitting unit 7.

  When the ceramic material is sintered together with the phosphor, it is preferable to use powder particles having a purity as high as possible and 0.5 μm to 2 μm.

  After the mixing step, the mixed powder is subjected to injection molding and molded into a desired shape (molding step). The injection molding method is particularly effective because the molded product can be used for the next sintering step as it is injected, and the dispersibility of the phosphor contained in the molded product is excellent.

  After the molding process, first, a binder removal process is performed. Here, by applying a temperature of about 400 ° C. to 600 ° C., the binder is decomposed and evaporated by a depolymerization reaction or the like. Thereafter, the molded product is sintered (sintering process). Here, a grain boundary (an interface between crystal grains or an interface between particles) can be generated in the sintered product by sintering the molded product. The presence of the grain boundary causes the following effects. Specifically, when laser light having a coherent component that is likely to damage the human eye is used as excitation light, the laser light is scattered by the grain boundary. And the safety | security of a light-emitting device can be improved by the magnitude | size of a light emission point expanding.

  The sintering temperature in the sintering step is preferably about 0.6 to 0.8 times the melting point of the ceramic material, and is generally about 800 ° C to 1500 ° C. However, the sintering temperature can be lowered by using a sintering aid. The firing time may be realized by, for example, a configuration in which the binder removal step is performed at 500 ° C. for 3 hours and then 1200 ° C. is maintained for 2 hours. However, the sintering time is not limited to the time listed here, and can be changed as appropriate.

  Further, the size of the grain boundary needs to be an area where light scattering occurs. For example, the size varies from a Rayleigh scattering region (grain boundary size of about 1 nm to several tens of nm) where the degree of scattering varies depending on the wavelength to a Mie scattering region or a diffraction scattering region (visible light region) that is scattered regardless of the wavelength. It is conceivable that the grain boundary size is about 100 nm to 50 μm, which is approximately the same as the wavelength.

  Furthermore, a method of producing the light emitting part by a melting process instead of the injection molding process and the sintering process is also conceivable. However, in that case, there may arise a problem that the phosphor inside the light emitting unit is not uniformly dispersed. Further, the grain boundary generated in the sintering process does not occur in the melting process, and therefore, it is impossible to achieve the effect of increasing the safety of the headlamp 1 by dispersing the laser light.

  For this reason, the headlamp 1 is preferably manufactured by the above-described mixing process, molding process, and sintering process. In addition, as long as the phosphor dispersed in the light emitting portion is a manufacturing method having uniformity and a manufacturing method in which grain boundaries are generated in the light emitting portion, the present invention is not limited to the mixing step, the molding step, and the sintering step. It is also possible to use a method.

(One Example of Manufacturing Method of Light Emitting Unit 7)
Here, an example of a method for manufacturing the light emitting unit 7 will be described.

As described above, when the ceramic material is sintered together with the phosphor, it is preferable to use powder particles having a purity as high as possible and 0.5 μm to 2 μm. Therefore, for example, when alumina is used as the ceramic material, the particle diameter is preferably 0.1 μm to 0.5 μm. The alumina fine particles, YAG: Ce ³⁺ phosphor, binder, and sintering aid are used. Are uniformly mixed in a mixing step and pelletized. At this time, the alumina fine particles, YAG: Ce ³⁺ and the binder are mixed at a ratio of 4: 1: 5. At this time, a small amount of a sintering aid may be added.

The mixed powder obtained by the mixing step is subjected to a molding step and a molding step to obtain a desired light emitting unit 7. In the present embodiment, in the sintering process, the molded product obtained in the molding process is degreased under reduced pressure heating and sintered in N ₂ gas.

However, degreasing under reduced pressure heating and sintering in N ₂ gas are not necessarily required. However, in the case of using YAG: Ce ³⁺ as the phosphor material, when the molded product is heated in an atmosphere containing oxygen, there is a problem that Ce ³⁺ becomes Ce ²⁺ and becomes colored and the light emission efficiency is lowered. For this reason, a more suitable sintered light-emitting body is produced by adding degreasing under reduced pressure heating, sintering in N ₂ gas, and other operations depending on the case depending on conditions such as the phosphor material. be able to.

Furthermore, as the phosphor material, in addition to YAG: Ce ³⁺ , an oxynitride phosphor can be preferably used. If a 405 nm semiconductor laser is used as the excitation light source, JEM as a blue phosphor, β-SiAlON: Eu ²⁺ as a green phosphor, and CASN: Eu ²⁺ as a red phosphor can be used. Here CASN as a red phosphor: SCASN instead of ^{Eu 2+} Sr (strontium) was added: The use of ^{Eu 2+,} although the color rendering properties become slightly sacrificed, it is possible to improve the luminous efficiency. If the use of the semiconductor laser that oscillates at 450nm around as an excitation light source, β-SiAlON: CASN as ^{Eu 2+} and red phosphor: ^{Eu 2+} or, SCASN: may use the ^{Eu 2+.}

(Structure of semiconductor laser 3)
Next, the basic structure of the semiconductor laser 3 will be described. FIG. 5A schematically shows a circuit diagram of the semiconductor laser 3, and FIG. 5B is a perspective view showing a basic structure of the semiconductor laser 3. As shown in the figure, the semiconductor laser 3 has a configuration in which a cathode electrode 23, a substrate 22, a clad layer 113, an active layer 111, a clad layer 112, and an anode electrode 21 are laminated in this order.

The substrate 22 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 21 is for injecting a current into the active layer 111 through the cladding layer 112.

  The cathode electrode 23 is for injecting current into the active layer 111 from the lower part of the substrate 22 through the clad layer 113. The current is injected by applying a forward bias to the anode electrode 21 and the cathode electrode 23.

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

  As the material for the active layer 111 and the cladding layer, 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. Moreover, you may be comprised by II-VI group compound semiconductors, 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 emitted from the light emitting point 103 from the front-side cleavage surface 114 which is a low reflectance end face.

  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, or any other II-VI compound semiconductor, and by applying a forward bias to the anode electrode 21 and the cathode electrode 23, 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 the light emitting unit 7)
Next, the light emission principle of the phosphor by the laser light oscillated from the semiconductor laser 3 will be described.

  First, the laser light oscillated from the semiconductor laser 3 is irradiated onto the phosphor included in the light emitting unit 7, 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.

(Effect of headlamp 1)
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, the sialon phosphor described above generates light with an efficiency of 60 to 80% when irradiated with laser light, but the rest is emitted as heat.

  In this regard, in the headlamp 1, the light emitting unit 7 is obtained by sintering a ceramic material such as alumina and a phosphor that emits light by receiving laser light emitted from the semiconductor laser 3 using a binder. Therefore, the light emitting unit 7 has high thermal conductivity, the heat of the light emitting unit 7 is efficiently transmitted to the heat conducting member 13, and the light emitting unit 7 is effectively radiated. Thereby, deterioration of the light emission part 7 by the heat_generation | fever and the fall of luminous efficiency can be prevented.

Therefore, it is possible to extend the life of the headlamp as an ultra-bright light source using laser light as an excitation light source, and to improve its reliability.
[Comparison between conventional light emitting device and headlamp 1]
Next, the effects obtained by the headlamp 1 will be described with reference to Tables 1 and 2.
[Table 1: Material of light emitting part]

  As shown in Table 1, the effect of the headlamp 1 will be considered by comparing a conventional light emitting device using inorganic glass as a sealing material for a light emitting portion with a headlamp 1 using alumina as a ceramic material.

  As shown in Table 1, the thermal conductivity of inorganic glass is 1 W / mK, and the thermal conductivity of alumina is 20 W / mK. In the light emitting portion, oxynitride phosphors (Caα-SiAlON: Ce and CASN: Eu) are dispersed inside, and are in the shape of a disk having a diameter of 3 mm and a thickness of 1.5 mm.

  Here, the thermal conductivity of a general sealing material for sealing a phosphor is about 0.1 W / mK to 0.2 W / mK for silicon resin or organic-inorganic hybrid glass, and 1 W / mK to 2 W for inorganic glass. / MK or so. For example, a thermal simulation in which a heat generating element having a thermal conductivity of 0.2 W / mK has a heat generation of 1 W on a 3 mm × 3 mm plane of a heating element of 3 mm × 3 mm × thickness 1 mm, and the heating element is thermally insulated from the outside. , The temperature of the heating element is 500 ° C. or higher (555.6 ° C.).

  Incidentally, if a sealing material having a thermal conductivity of 2 W / mK is used, the temperature rise will be 55.6 ° C. even if the heating element has the same size and the same heating value. That is, the thermal conductivity of the encapsulant is very important. If the heat conductivity of the encapsulant is 2 W / mK and the size of the heating element is 3 mm × 1 mm × thickness 1 mm, the temperature rise is 166.7 ° C. Therefore, the smaller the size of the light emitting unit 7 in order to increase the luminance, the more the temperature rises even with the same amount of heat generation, and the light emitting unit 7 is burdened.

  Against this background, the effect of the headlamp 1 will be considered while comparing the inorganic glass used in the conventional light emitting part with alumina having a thermal conductivity of 20 W / mK.

  First, in the above table, the thermal resistance of inorganic glass and alumina is calculated. The thermal resistance of each member can be calculated by the following equation (1).

Thermal resistance = (1 / thermal conductivity) × (heat dissipation path length / heat dissipation cross-sectional area) (1)
The length of the heat dissipation path corresponds to the thickness of each member (thickness in the laser beam transmission direction), and the heat dissipation cross-sectional area corresponds to the bonding area between the members. Table 2 shows a specific calculation example of thermal resistance.
[Table 2: Calculation example of thermal resistance]

  As shown in Table 2, when inorganic glass and alumina are compared, the thermal resistance of the light emitting part is 83.3 K / W for inorganic glass and 4.2 K / W for alumina. That is, when 1 W of heat is generated in the light emitting portion, an increase in temperature of 83.3 ° C. is assumed for inorganic glass, whereas it is suppressed to 4.2 ° C. for alumina. Therefore, by using alumina having a thermal conductivity of 20 W / mK, the thermal resistance of the light emitting part can be dramatically reduced. That is, it can be seen that improving the thermal conductivity of the material constituting the light emitting part has a very large effect for the purpose of reducing the temperature rise of the light emitting part.

For this reason, the light emitting unit 7 according to the headlamp 1 can have high thermal conductivity, the heat of the light emitting unit 7 is efficiently transmitted to the heat conducting member 13, and the light emitting unit 7 is effectively radiated. . Thereby, deterioration of the light emission part 7 by the heat_generation | fever and the fall of luminous efficiency can be prevented.
[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.

  Here, the laser downlight 200 as an example of the illuminating device of this invention is demonstrated. The laser downlight 200 is an illumination 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 7 with laser light emitted from the semiconductor laser 3 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. 6 is a schematic view showing the appearance of the light emitting unit 210 and the conventional LED downlight 300. FIG. 7 is a cross-sectional view of the ceiling where the laser downlight 200 is installed. FIG. 8 is a cross-sectional view of the laser downlight 200. As shown in FIGS. 6 to 8, 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 5. 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 5. The optical fiber 5 is disposed in a gap between the top plate 400 and the heat insulating material 401.

(Configuration of light emitting unit 210)
As shown in FIG. 8, the light emitting unit 210 includes a housing 211, an optical fiber 5, a light emitting unit 7, a heat conducting member 13, and a light transmitting plate 213. Although not shown in FIG. 8, the high thermal conductive filler 15 is dispersed in the light emitting portion 7. Similarly to the above-described embodiment, heat of the light emitting unit 7 is transmitted to the heat conducting member 13, so that heat dissipation of the light emitting unit 7 is promoted.

  A recess 212 is formed in the housing 211, and the light emitting unit 7 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 5 is formed in the housing 211, and the optical fiber 5 extends to the heat conducting member 13 through the passage 214. The laser beam emitted from the emission end 5 a of the optical fiber 5 passes through the heat conducting member 13 and reaches the light emitting unit 7.

  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 7 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 FIG. 6, the light emitting unit 210 has a circular outer edge, but the shape of the light emitting unit 210 (more strictly, the shape of the housing 211) is not particularly limited.

  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 section 7 than in the case of the headlamp.

(Configuration of LD light source unit 220)
The LD light source unit 220 includes a semiconductor laser 3, an aspheric lens 4, and an optical fiber 5.

  The incident end 5b, which is one end of the optical fiber 5, is connected to the LD light source unit 220, and the laser light oscillated from the semiconductor laser 3 is incident on the incident end 5b of the optical fiber 5 via the aspherical lens 4. Is incident on.

  Only one pair of the semiconductor laser 3 and the aspherical lens 4 is shown inside the LD light source unit 220 shown in FIG. 8, but when there are a plurality of light emitting units 210, the optical fibers 5 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 3 and aspherical lenses 4 are accommodated in one LD light source unit 220, and the LD light source unit 220 functions as a centralized power supply box.

(Example of changing the installation method of the laser downlight 200)
FIG. 9 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 which the optical fiber 5 passes is formed 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) may be attached to the top board 400. 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.

  In this configuration, the heat conducting member 13 is disposed at the bottom of the casing 211 with the surface on the laser light incident side in contact with the entire surface. Therefore, the casing 211 can be made to function as a cooling unit for the heat conducting member 13 by being made of a material having high thermal conductivity.

(Comparison between laser downlight 200 and conventional LED downlight 300)
As shown in FIG. 6, the conventional LED downlight 300 includes a plurality of light transmitting plates 301, and illumination light is emitted from each light transmitting plate 301. That is, the LED downlight 300 has a plurality of light emitting points. The LED downlight 300 has a plurality of light emitting points because the light flux of light emitted from each light emitting point is relatively small. Therefore, if a plurality of light emitting points are not provided, light having a sufficient light flux as illumination light is provided. This is because it cannot be obtained.

  On the other hand, since the laser downlight 200 is an illumination device with a high luminous flux, the number of emission points may be one. Therefore, it is possible to obtain an effect that the shadow caused by the illumination light is clearly displayed. Moreover, the color rendering property of illumination light can be improved by making the phosphor of the light emitting portion 7 a high color rendering phosphor (for example, a combination of several kinds of oxynitride phosphors).

  Thereby, the high color rendering which approaches an incandescent bulb downlight is realizable. For example, not only an average color rendering index Ra of 90 or more but also a special color rendering index R9 of 95 or more, high color rendering light that is difficult to realize with LED downlights or fluorescent lamp downlights can be obtained by combining the high color rendering phosphor and the semiconductor laser 3. It is feasible.

  FIG. 10 is a cross-sectional view of the ceiling where the LED downlight 300 is installed. As shown in the figure, in the LED downlight 300, a casing 302 that houses an LED chip, a power source, and a cooling unit is embedded in the top plate 400. The housing 302 is relatively large, and a recess along the shape of the housing 302 is formed in a portion of the heat insulating material 401 where the housing 302 is disposed. A power line 303 extends from the housing 302, and the power line 303 is connected to an outlet (not shown).

  Such a configuration causes the following problems. First, since there is a light source (LED chip) and a power source that are heat sources between the top plate 400 and the heat insulating material 401, the use of the LED downlight 300 raises the ceiling temperature, and the cooling efficiency of the room. Problem arises.

  Further, the LED downlight 300 requires a power source and a cooling unit for each light source, which causes a problem that the total cost increases.

  Moreover, since the housing | casing 302 is comparatively large, the problem that it is often difficult to arrange | position the LED downlight 300 in the clearance gap between the top plate 400 and the heat insulating material 401 arises.

  On the other hand, in the laser downlight 200, since the light emitting unit 210 does not include a large heat source, the cooling efficiency of the room is not reduced. As a result, an increase in room cooling costs can be avoided.

  Further, since it is not necessary to provide a power source and a cooling unit for each light emitting unit 210, the laser downlight 200 can be reduced in size and thickness. As a result, the space restriction for installing the laser downlight 200 is reduced, and installation in an existing house is facilitated.

  Further, since the laser downlight 200 is small and thin, as described above, the light emitting unit 210 can be installed on the surface of the top plate 400, and the installation restrictions are made smaller than those of the LED downlight 300. As well as drastically reducing construction costs.

  FIG. 11 is a diagram for comparing the specifications of the laser downlight 200 and the LED downlight 300. As shown in the figure, in the laser downlight 200, in one example, the volume is reduced by 94% and the mass is reduced by 86% compared to the LED downlight 300.

  Further, since the LD light source unit 220 can be installed in a place where the user can easily reach, the semiconductor laser 3 can be easily replaced even if the semiconductor laser 3 breaks down. Further, by guiding the optical fibers 5 extending from the plurality of light emitting units 210 to one LD light source unit 220, the plurality of semiconductor lasers 3 can be collectively managed. Therefore, even when a plurality of semiconductor lasers 3 are replaced, the replacement can be easily performed.

  In the case of a type using a high color rendering phosphor in the LED downlight 300, a light beam of about 500 lm can be emitted with a power consumption of 10 W, but in order to realize the light of the same brightness with the laser downlight 200, 3 .3W light output is required. If the LD efficiency is 35%, this light output corresponds to power consumption of 10 W, and the power consumption of the LED downlight 300 is also 10 W. Therefore, there is no significant difference in power consumption between the two. Therefore, in the laser downlight 200, the above-described various advantages can be obtained with the same power consumption as that of the LED downlight 300.

  As described above, the laser downlight 200 includes the LD light source unit 220 including at least one semiconductor laser 3 that emits laser light, the at least one light emitting unit 210 including the light emitting unit 7 and the recess 212 as a reflecting mirror, And an optical fiber 5 that guides the laser light to each of the light emitting units 210.

(Other changes)
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.

  For example, a high-power LED may be used as the excitation light source. In this case, a light emitting device that emits white light can be realized by combining an LED that emits light having a wavelength of 450 nm (blue) and a yellow phosphor or green and red phosphors.

  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.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a sintered light emitter that can reduce the thermal resistance of the light emitting portion and, as a result, can efficiently dissipate the light emitting portion. The present invention can be suitably applied to a lighting device to be used and a vehicle headlamp.

1 Headlamp (light emitting device)
2 Semiconductor laser array 3 Semiconductor laser (excitation light source)
4 Aspherical lens 5 Optical fiber 6 Ferrule 7 Light emitting part (sintered light emitting body)
8 Reflecting mirror 9 Transparent plate 10 Housing 11 Extension 12 Lens 13 Heat conduction member 14 Cooling unit 16 Phosphor particles (phosphor)
18 Heat conduction wall (heat conduction member)
200 Laser downlight (light emitting device, lighting device)

Claims (13)

A sintered light-emitting body characterized in that a ceramic material and a phosphor that emits light by excitation light emitted from an excitation light source are sintered using a binder and have a grain boundary inside .   The sintered light-emitting body according to claim 1, wherein the ceramic material has high thermal conductivity.   The sintered light-emitting body according to claim 1 or 2, wherein the ceramic material contains alumina or aluminum nitride.   The sintered body according to any one of claims 1 to 3, wherein the sintered light emitting body is obtained by injection molding and sintering a mixture of the ceramic material, the phosphor, and the binder. Condensed light emitter.   The sintered light-emitting body according to any one of claims 1 to 4, wherein the ceramic material has translucency.   The sintered phosphor according to any one of claims 1 to 5, wherein the phosphor is an oxynitride phosphor.   The sintered phosphor according to any one of claims 1 to 5, wherein the phosphor is a nanoparticle phosphor. An excitation light source that emits the excitation light;
The sintered light-emitting body according to any one of claims 1 to 7,
A light emitting device comprising:   The light emitting device according to claim 8, wherein the excitation light is laser light.   The light-emitting device according to claim 8, further comprising a heat conductive member that contacts the sintered light-emitting body and dissipates heat of the sintered light-emitting body to the outside.   An illumination device comprising the light-emitting device according to claim 8.   A vehicle headlamp comprising the light-emitting device according to claim 8. A method for producing a sintered light-emitting body according to any one of claims 1 to 7,
A mixing step of mixing a ceramic material and a phosphor that emits light by excitation light emitted from an excitation light source and a binder;
A sintering step of sintering the mixture mixed by the mixing step;
A method for producing a sintered luminescent material, comprising:

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