JP5181045B2 - Light emitting device, lighting device, vehicle headlamp - Google Patents

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.

  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 to solve the above-described problems, and an object of the present invention is to reduce the thermal resistance of the light emitting unit, and as a result, to efficiently radiate the light emitting unit, the light emitting device, the lighting device, and The object is to provide a vehicular headlamp.

  In order to solve the above-described problem, a light-emitting device according to the present invention includes an excitation light source that emits excitation light and a light-emitting unit that includes a phosphor that emits light by excitation light emitted from the excitation light source. The section is characterized by containing thermally conductive particles.

  According to the above configuration, the light emitting unit emits light upon receiving the excitation light. At this time, the excitation light that has not been converted into fluorescence becomes heat, and the light emitting unit generates heat. Since the light emitting part contains heat conductive particles, its thermal resistance is lowered. Therefore, the heat of the light emitting part can be efficiently radiated.

  Moreover, the light emitting part is obtained by sealing the phosphor with a sealing material, and the thermal conductivity of the heat conductive particles is preferably higher than the thermal conductivity of the sealing material.

  According to said structure, the heat conductivity of a heat conductive particle is higher than that of a sealing material. Therefore, the thermal resistance of the light emitting part can be reduced more effectively.

  Moreover, it is preferable that the said heat conductive particle has translucency.

  According to said structure, since heat conductive particles have translucency, possibility that the excitation light from an excitation light source and the fluorescence which fluorescent substance emits will be shielded falls. Therefore, the utilization efficiency (emission efficiency) of excitation light can be increased.

  Moreover, it is preferable that the heat conductive particles and the phosphor are dispersed in the light emitting portion in a state of being in contact with each other.

  According to said structure, the efficiency which heat transfers from a fluorescent substance to a heat conductive particle can be improved by making heat conductive particle and fluorescent substance adhere beforehand. As a result, the thermal resistance of the light emitting part can be reduced more effectively.

  A plurality of phosphor particles may be attached to the surface of one heat conductive particle, or a plurality of heat conductive particles may be attached to the surface of one phosphor particle.

  Moreover, it is preferable to further include a heat conducting member that contacts the light emitting unit and receives heat from the light emitting unit.

  According to said structure, the heat dissipation efficiency of a light emission part can 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.

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

  A manufacturing method according to the present invention is a method of manufacturing a light emitting unit that emits light upon receiving excitation light in order to solve the above-described problem, and includes a mixing step of mixing heat conductive particles, a phosphor, and a sealing material; And a baking step of baking the mixture mixed in the mixing step.

  The light emitting portion emits light upon receiving the excitation light. At this time, the excitation light that has not been converted into fluorescence becomes heat, and the light emitting portion generates heat.

  According to said structure, a light emission part is formed by mixing a heat conductive particle, fluorescent substance, and a sealing material, and baking. Since this light emitting part contains heat conductive particles, its thermal resistance is lowered. Therefore, the heat of the light emitting part can be efficiently radiated.

  Further, it is preferable that the method further includes an attaching step of attaching the heat conducting particles and the phosphor to each other, and the composite of the heat conducting particles and the phosphor formed in the attaching step is mixed with the sealing material in the mixing step. .

  According to said structure, a light emission part is formed by sealing in the state in which the heat conductive particle and fluorescent substance adhered to each other. Therefore, the heat of the phosphor generated when the excitation light is irradiated is efficiently transmitted to the heat conducting particles. Therefore, the effect of reducing the thermal resistance of the light emitting part by the heat conductive particles can be further enhanced.

  As described above, the light-emitting device according to the present invention includes the excitation light source that emits excitation light and the light-emitting unit that includes the phosphor that emits light by the excitation light emitted from the excitation light source. The configuration includes conductive particles.

  The manufacturing method which concerns on invention is the structure containing the mixing process which mixes a heat conductive particle, fluorescent substance, and a sealing material, and the baking process which bakes the mixture mixed in the said mixing process.

  Therefore, there is an effect that the thermal resistance of the light emitting part can be reduced and the light emitting part can be efficiently dissipated.

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 a conceptual diagram which shows the state in which the high heat conductive filler and fluorescent substance particle are disperse | distributing in the glass material in the light emission part. (A) is a figure which shows the state by which the several fluorescent substance particle is distribute | arranged on the surface of a high heat conductive filler, (b) is the state by which the several high heat conductive filler is distribute | arranged on the surface of the fluorescent substance particle. FIG. It is sectional drawing which shows the example of a change of the said 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 a figure which shows the specific example of the light emission part with which the said headlamp is provided, and a heat conductive member. It is the schematic which shows the structure of the headlamp which concerns on another embodiment of this invention. (A)-(c) is a figure which shows the modification of a fixing | fixed part, (d) is a figure which shows the structure which connects a light emission part to a heat conductive member by an adhesive layer. 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]
The following describes one embodiment of the present invention 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 aspheric lens 4, an optical fiber 5, a ferrule 6, a light emitting unit 7, a reflecting mirror 8, a transparent plate 9, and 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 light oscillated by the semiconductor laser 3 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. 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.

  If a high-quality short-wavelength semiconductor laser that oscillates laser light having a wavelength smaller than 380 nm can be manufactured, the laser light having a wavelength smaller than 380 nm is oscillated as the semiconductor laser 3 of the present embodiment. It is also possible to use a semiconductor laser designed as described above.

  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 (excitation light 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 illustrating details of the light emitting unit 7 and the heat conducting member 13 included in the headlamp 1. The light emitting part (wavelength converting member) 7 emits light upon receiving the laser light emitted from the emitting end part 5a, and includes a phosphor that emits light upon receiving the laser light, and a high thermal conductive filler (thermal conductive particle) 15. Contains. The phosphor and the high thermal conductive filler 15 are dispersed inside a glass material as a sealing material.

  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.

(Encapsulant)
As the sealing material, for example, an inorganic glass of about 1 W / mK can be used. The ratio between the glass material and the phosphor is about 10: 1.

  The sealing material is not limited to inorganic glass, and may be a resin material such as so-called organic-inorganic hybrid glass or silicone resin. However, when inorganic glass is used as the sealing material, the effect of increasing the heat resistance and lowering the thermal resistance of the light emitting portion 7 is obtained, and therefore inorganic glass is preferable.

(High thermal conductive filler 15)
The high thermal conductive filler 15 is, for example, Al ₂ O ₃ (sapphire) beads having a thermal conductivity of about 20 to 40 W / mK, and diamond beads having a thermal conductivity of about 1000 to 2000 W / mK. Since the melting point of Al ₂ O ₃ beads is 2030 ° C. and the melting point of diamond is 3550 ° C., it does not melt or deteriorate at the melting temperature of ordinary inorganic glass.

  In order to increase the thermal conductivity of the light emitting unit 7, the thermal conductivity of the high thermal conductive filler 15 is preferably higher than the thermal conductivity of the sealing material, and more preferably, the thermal conductivity of the high thermal conductive filler 15 is: It is higher than the thermal conductivity of the phosphor.

  Moreover, the high thermal conductive filler 15 is preferably one having high translucency. When the translucency is low, the high thermal conductive filler 15 may block or absorb the laser light from the semiconductor laser 3 and the fluorescence emitted by the phosphor. Therefore, it is preferable that the high thermal conductivity filler 15 has high translucency from the viewpoint of the utilization efficiency of laser light.

(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.

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.

(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.

(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 conduction member (high heat conduction member) 13 is disposed on the side of the laser light irradiation surface (excitation light irradiation surface) 7 a that is the surface irradiated with the excitation light in the light emitting unit 7, and transmits light that receives the heat of the light emitting unit 7. And is thermally connected to the light-emitting portion 7 (that is, to be able to exchange heat energy). 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.

(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.

(Examples of material combinations for each part)
Next, an example of a combination of materials of the light emitting part 7, the heat conductive member 13, and an adhesive used when both are bonded will be described with reference to Table 1 and Table 2.

  As shown in Table 1, when inorganic glass is used as the sealing material for the light emitting portion 7 and diamond or sapphire particles are included in the light emitting portion 7 as the high thermal conductive filler 15, the heat conductivity of the light emitting portion 7 is high. Become. As a result, the thermal resistance of the light emitting unit 7 is lowered.

  As shown in Table 2, by using a material such as sapphire having a high thermal conductivity for the heat conducting member 13 as well, the heat resistance of the heat conducting member 13 is lowered, and the heat absorption efficiency and the heat radiation efficiency of the heat conducting member 13 are increased. .

  The thermal resistance of each member can be calculated by the following equation (1).

Thermal resistance = (1 / thermal conductivity) · (length of heat dissipation path / 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 3 shows a specific calculation example of thermal resistance.

  As shown in Table 3, when it is assumed that the light emitting unit 7 is formed only of the sealing material, the thermal resistance of the light emitting unit 7 is larger than the thermal resistance of the adhesive and the heat conducting member 13. Actually, since the light emitting portion 7 contains a phosphor having a higher thermal conductivity than the sealing material, the thermal resistance of the light emitting portion 7 is lower than that shown in Table 3. However, the thermal resistance of the light emitting unit 7 is still higher by one digit or more than the thermal resistance of the heat conducting member 13.

  Therefore, the thermal resistance of the light emitting unit 7 can be lowered by mixing the high thermal conductive filler 15 with the light emitting unit 7.

  For example, when 8% of sapphire fine particles (diameter 10 μm) having a thermal conductivity of 25 W / mK are mixed in the light emitting part 7, the heat dissipation effect is about 1.4 times, although it is affected by the dispersion state in the light emitting part 7. A simulation result that increases is obtained. Further, from the actual measurement result of the temperature rise state of the light emitting part using thermography, almost the same heat generation suppressing effect (in the case of no high heat conductive filler, the temperature rises by 100 ° C., but when 8% of sapphire fine particles are mixed, it is 70. It was found that there was a temperature rise of just over ℃).

(How to improve thermal resistance)
Next, a method for reducing the thermal resistance of each member and increasing the heat dissipation effect will be described for each member.

<Light Emitting Unit 7>
In order to reduce the thermal resistance of the light emitting unit 7, the following change is effective.
-Increase the mixing amount of the high thermal conductive filler 15.
・ Increase heat dissipation area (contact area with other members). For example, a member having high thermal conductivity is brought into contact with the surface of the light emitting unit 7 facing the laser light irradiation surface 7a.
-The thickness of the light emitting part 7 is reduced.

  However, if the heat radiation area is increased by bringing more members into contact with the light emitting unit 7, the luminance of the light emitting unit 7 may be reduced. Further, by reducing the volume of the light emitting unit 7 and reducing the thickness of the light emitting unit 7, there is a possibility that the luminous flux is reduced or the luminance uniformity is reduced. Further, if the structure of the light emitting unit 7 is complicated in order to increase the heat dissipation area, the manufacturing cost may be increased.

  Therefore, it is preferable to select an appropriate method for reducing the thermal resistance of the light emitting unit 7 in consideration of these disadvantages.

  The thermal conductivity of the light emitting unit 7 depends not only on the material of the high thermal conductive filler to be mixed but also on its concentration (mixing ratio). For example, the thermal conductivity is higher when a relatively large amount of sapphire beads are mixed than when a very small amount of diamond paste is mixed. Therefore, the thermal conductivity of the light emitting unit 7 may be adjusted by adjusting the material and amount of the high thermal conductive filler to be mixed in the light emitting unit 7.

  A plurality of types of high thermal conductive fillers may be mixed in the light emitting unit 7.

  Moreover, you may form the light emission part 7 from fluorescent substance and the high heat conductive filler 15 without using a sealing material.

<Adhesive>
The following changes are effective to reduce the thermal resistance of the adhesive.
-Increase the heat dissipation area (contact area with the light emitting part 7).
-Reduce the thickness of the adhesive.
-Increase the thermal conductivity of the adhesive. For example, a material having a high thermal conductivity (for example, a low-melting-point inorganic glass paste that is sintered by heating) is used as the adhesive.

  Note that the thermal resistance of the adhesive can be lowered by mixing a high thermal conductive filler with the adhesive, but when a high thermal conductive filler is mixed with the inorganic glass-based paste, a transparent and low melting point paste should be realized. It is difficult.

  Further, as shown in a second embodiment described later, the influence of the adhesive may be eliminated by bringing the light emitting portion 7 into contact with the heat conducting member 13 by a fixing member without using an adhesive.

<Heat conduction member 13>
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.

  However, when a metal thin film or the like is formed on the surface of the heat conducting member 13, the luminous flux may be reduced. In addition, when the surface of the heat conducting member 13 is covered or another member is disposed, the manufacturing cost increases.

(Manufacturing method of the light emission part 7)
Next, the manufacturing method of the light emission part 7 is demonstrated. FIG. 3 is a conceptual diagram illustrating a state in which the high thermal conductive filler 15 and the phosphor particles 16 are dispersed in the inorganic glass 17 in the light emitting unit 7.

  First, each powder is weighed so that the glass powder, the phosphor powder, and the high thermal conductive filler 15 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.

  When the concentration of the phosphor in the light emitting portion 7 is high, it is preferable that the phosphor particles 16 are uniformly dispersed in the sealing material as shown in FIG. This is because if the phosphor particles 16 are gathered in 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.

  The high thermal conductive filler 15 is also preferably uniformly dispersed in the sealing material because the effect of lowering the thermal resistance reaches the entire light emitting portion 7.

  After the mixing step, the mixed powder is put in a metal mold and fired, for example, at 560 ° C. for 0.5 hour (firing step).

  As shown in FIG. 3, when the high thermal conductive filler 15 and the phosphor particles 16 are not in contact, the heat of the phosphor particles 16 is conducted to the high thermal conductive filler 15 through the inorganic glass 17. Therefore, the effect of lowering the thermal resistance of the high thermal conductive filler 15 may not be sufficiently obtained.

  In order to solve this problem, the phosphor particles 16 and the high thermal conductive filler 15 are previously attached to each other (attachment step), and the composite of the phosphor particles 16 and the high thermal conductive filler 15 is mixed with the glass powder. It is preferable to sinter. That is, it is preferable that the high thermal conductive filler 15 and the phosphor particles 16 are dispersed in the light emitting portion 7 in a state where they are in contact with each other.

  The adhesive force between the phosphor particles 16 and the high thermal conductive filler 15 is such that the phosphor particles 16 and the high thermal conductive filler 15 do not deviate in the process of mixing and sintering the composite with a sealing material. That's fine.

  FIG. 4A is a diagram showing a state in which a plurality of phosphor particles 16 are arranged on the surface of the high thermal conductive filler 15, and FIG. 4B is a diagram showing a plurality of high thermal conductivity on the surface of the phosphor particles 16. It is a figure which shows the state by which the filler 15 is distribute | arranged. As shown in FIG. 4A, when the particle size of the high thermal conductive filler 15 is larger than the particle size of the phosphor particles 16, a plurality of phosphor particles 16 may be provided on the surface of the high thermal conductive filler 15. . Conversely, as shown in FIG. 4B, when the particle diameter of the high thermal conductive filler 15 is smaller than the particle diameter of the phosphor particles 16, a plurality of high thermal conductive fillers 15 are provided on the surface of the phosphor particles 16. Just do it.

  As a method of adhering the phosphor particles 16 and the high thermal conductive filler 15 to each other, for example, the adhering particles (or the liquid containing the adhering particles) are attached to the object to be adhered by a granulation operation using a dry method, a wet coating method, or a spray drying method. The method of spraying with respect to particle | grains is mentioned. The attached particles are particles having a smaller particle size among the high thermal conductive filler 15 and the phosphor particles 16, and the particles to be attached are the particle sizes of the high thermal conductive filler 15 and the phosphor particles 16. Is the larger particle.

  Further, the phosphor particles 16 and the high thermal conductive filler 15 may be adhered by an adhesive, or both may be adhered using static electricity.

(Modification example of the light emitting unit 7)
FIG. 5 is a cross-sectional view showing a modified example of the light emitting unit 7. As shown in FIG. 5, a heat conductive wall 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.

(Structure of semiconductor laser 3)
Next, the basic structure of the semiconductor laser 3 will be described. FIG. 6A schematically shows a circuit diagram of the semiconductor laser 3, and FIG. 6B is a perspective view showing the 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 7 is excited with high-power laser light, the light emitting portion 7 is severely deteriorated. The deterioration of the light emitting unit 7 is mainly caused by the deterioration of the phosphor itself included in the light emitting unit 7 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 the headlamp 1, since the light emitting portion 7 includes the high thermal conductive filler 15, the thermal resistance of the light emitting portion 7 is lower than that of the conventional one. Therefore, 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.

  Next, an embodiment of the present invention will be described with reference to FIG. FIG. 7 is a diagram illustrating a specific example of the light emitting unit 7 and the heat conducting member 13.

  As the light emitting portion 7, a wavelength conversion member in which an oxynitride phosphor (Caα-SiAlON: Ce and CASN: Eu) is dispersed in a sealing material is used. The light emitting portion 7 is a disc-shaped member having a diameter of 3 mm and a thickness of 1.5 mm. In the light emitting part 7, sapphire beads are dispersed as the high thermal conductive filler 15.

As a lower limit value of a preferable density range (mixing ratio range) in the light emitting portion 7 of the high thermal conductive filler 15,
(Thermal conductivity of thermally conductive filler) x (mixing ratio)> (Thermal conductivity of sealing material)
Those satisfying the condition shown by For example, if the thermal conductivity of the high thermal conductive filler 15 is 25 W / mK, a value of 25 × 0.04 = 1 W / mK is obtained when 4% (volume%) is mixed in the light emitting portion 7. This value is the same as the thermal conductivity of the glass material used as the sealing material. In this state, the effect of improving the thermal conductivity (or thermal resistance) of the light-emitting portion 7 is actually obtained remarkably. It is considered impossible.

  As described above, when 8% of sapphire beads are mixed in the light emitting portion 7, the heat dissipation effect is increased by about 1.4 times.

  On the other hand, the upper limit value of the preferable density range (mixing ratio range) in the light emitting portion 7 of the high thermal conductive filler 15 is the mixing ratio when the sealing material is entirely replaced with the high thermal conductive filler 15.

  A sapphire plate having a thickness of 0.5 mm (thermal conductivity: 42 W / mK) is used as the heat conductive member 13, and a visible light polymerization type optical adhesive Epicacol (Epixacolle) EP433 manufactured by Adel is used as the heat conductive member 13. The light emitting part 7 was adhered by using it. This state is shown in FIG.

  In the case of a light emitting part made of Caα-SiAlON: Ce and CASN: Eu, the efficiency of converting excitation light into illumination light (fluorescence) is about 70%. When 10 W of excitation light is irradiated, 3 W of that is converted into heat without being converted into illumination light.

  The thermal conductivity of the sealing material for sealing the phosphor is about 0.1 to 0.2 W / mK for silicone resin and organic-inorganic hybrid glass, and about 1 to 2 W / mK for inorganic glass. 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.

  On the other hand, a heat conduction plate (3 mm × 10 mm × thickness 0.5 mm) having a heat conductivity of 40 W / mK is applied to the above-described heating element (3 mm × 3 mm × thickness 1 mm, heat conductivity 0.2 W / mK). When thermally bonded, the temperature rise of the heating element can be suppressed to about 170 ° C. By setting the thickness of the heat conductive plate to 0.5 mm to 1.0 mm, the temperature rise can be suppressed to about 85 ° C., which is half. Moreover, since the heat dissipation to a heat conductive board improves by setting the thickness of a heat generating body to 1 mm to 0.5 mm, the temperature rise of a heat generating body can be reduced further.

  When the temperature of the phosphor light emitting part is set to about 200 ° C. or less, and an oxynitride phosphor or a group III-V compound semiconductor nanoparticle phosphor is used as the phosphor, heat is generated particularly in the light emitting part 7. Even if extremely strong excitation light exceeding 1 W is irradiated, the generated heat is quickly and efficiently dissipated, and the light emitting section 7 can be prevented from being damaged (deteriorated).

  Moreover, as a sealing material which comprises this light emission part 7, inorganic glass is preferable, and when using a silicone resin, it is preferable to carry out a heat | fever simulation strictly and to suppress a temperature rise to about 150 degrees C or less. In the case of organic-inorganic hybrid glass, the temperature is allowed to be about 250 ° C. to about 300 ° C. In the case of inorganic glass, there is no problem even if it is 500 ° C. or higher as long as it is below the melting point of the material.

[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. In the present embodiment, another example of a member that sandwiches the light emitting unit 7 together with the heat conducting member 13 will be described.

(Configuration of the headlamp 30)
FIG. 8 is a schematic diagram showing the configuration of the headlamp 30 of the present embodiment. As shown in the figure, the headlamp 30 includes a transparent plate (fixed portion) 19, a metal ring 20, a reflecting mirror 81, a substrate 82, and screws 83. In the headlamp 30, the light emitting unit 7 is sandwiched between the heat conducting member 13 and the transparent plate 19.

(Light Emitting Unit 7)
The light emitting unit 7 is bonded to the heat conducting member 13 with an adhesive and is disposed in an opening formed at the bottom of the metal ring 20. High heat conductive filler 15 is dispersed inside the light emitting portion 7 (not shown in FIG. 7).

(Reflector 81)
The reflecting mirror 81 has a function similar to that of the reflecting mirror 8, but has a shape cut by a plane perpendicular to the optical axis in the vicinity of the focal position. The material of the reflecting mirror 81 is not particularly limited, but considering the reflectance, it is preferable to produce a reflecting mirror using copper or SUS (stainless steel), and then apply silver plating, chromate coating, or the like. In addition, the reflecting mirror 81 may be manufactured using aluminum, an antioxidant film may be provided on the surface, or a metal thin film may be formed on the surface of the resinous reflecting mirror body.

(Metal ring 20)
The metal ring 20 is a mortar-shaped ring having a shape near the focal position when the reflecting mirror 81 is a perfect reflecting mirror, and has a shape in which the bottom of the mortar is open.

  The surface of the mortar-shaped portion of the metal ring 20 functions as a reflecting mirror, and a perfectly shaped reflecting mirror is formed by combining the metal ring 20 and the reflecting mirror 81. Therefore, the metal ring 20 is a partial reflecting mirror that functions as a part of the reflecting mirror. When the reflecting mirror 81 is referred to as a first partial reflecting mirror, it is referred to as a second partial reflecting mirror having a portion near the focal position. Can do. A part of the fluorescence emitted from the light emitting unit 7 is reflected by the surface of the metal ring 20 and emitted to the front of the headlamp 30 as illumination light.

  The material of the metal ring 20 is not particularly limited, but silver, copper, aluminum and the like are preferable in view of heat dissipation. When the metal ring 20 is silver or aluminum, it is preferable to provide a protective layer (chromate coat, resin layer, etc.) for preventing darkening and oxidation after finishing the mortar part to a mirror surface. Moreover, when the metal ring 20 is copper, it is preferable to provide the above-mentioned protective layer after silver plating or aluminum vapor deposition.

  Since the metal ring 20 is in contact with the heat conducting member 13, an effect of radiating the heat conducting member 13 is obtained. That is, the metal ring 20 also functions as a cooling unit for the heat conducting member 13.

(Transparent plate 19)
A transparent plate 19 is sandwiched between the metal ring 20 and the reflecting mirror 81. The transparent plate 19 is in contact with the surface opposite to the laser light irradiation surface 7 a of the light emitting unit 7, and has a role of suppressing the light emitting unit 7 from being peeled off from the heat conducting member 13. Since the depth of the mortar-shaped portion of the metal ring 20 is substantially the same as the height of the light emitting portion 7, the transparent plate 19 and the heat conducting member 13 are kept at a constant distance. 19 is in contact with the light emitting unit 7. Therefore, the light emitting unit 7 is not crushed by being sandwiched between the heat conducting member 13 and the transparent plate 19.

  The transparent plate 19 may be made of any material as long as it has at least translucency, but preferably has a high thermal conductivity (20 W / mK or more) like the heat conductive member 13. For example, the transparent plate 19 preferably contains sapphire, gallium nitride, magnesia or diamond. In this case, the transparent plate 19 has a high thermal conductivity and can efficiently absorb the heat generated in the light emitting unit 7.

  The thickness of the heat conducting member 13 and the transparent plate 19 is preferably about 0.3 mm or more and 3.0 mm or less. If the thickness is 0.3 mm or less, the strength to sandwich and fix the light emitting portion 7 and the metal ring 20 cannot be obtained. If the thickness is 3.0 mm or more, the absorption of laser light cannot be ignored and the member cost increases. Resulting in.

(Substrate 82)
The substrate 82 is a plate-like member having an opening 82 a through which the laser light emitted from the semiconductor laser 3 passes, and a reflecting mirror 81 is fixed to the substrate 82 with screws 83. The heat conducting member 13, the metal ring 20, and the transparent plate 19 are disposed between the reflecting mirror 81 and the substrate 82, and the center of the opening 82 a and the center of the opening at the bottom of the metal ring 20 substantially coincide with each other. ing. Therefore, the laser light emitted from the semiconductor laser 3 passes through the opening 82 a of the substrate 82, passes through the heat conducting member 13, and reaches the light emitting unit 7 through the opening of the metal ring 20.

  The material of the substrate 82 is not particularly limited. However, since the heat conducting member 13 is in full contact with the substrate 82, the heat conducting effect of the heat conducting member 13 can be improved by making the substrate 82 a metal such as iron or copper. Thus, the heat dissipation effect of the light emitting portion 7 can be enhanced.

  It is preferable that the metal ring 20 is securely fixed to the heat conducting member 13. The metal ring 20 can be fixed to the heat conducting member 13 to some extent by the pressure generated by fixing the substrate 82 and the reflecting mirror 81 with the screws 83. However, by fixing the metal ring 20 securely by a method such as bonding the metal ring 20 to the heat conducting member 13 with an adhesive or screwing the metal ring 20 to the substrate 82 with the heat conducting member 13 interposed therebetween, The risk that the light emitting part 7 is peeled off by the movement of the metal ring 20 can be avoided.

  The metal ring 20 may be any metal as long as it has a function as the above-described partial reflecting mirror and can withstand the pressure when the reflecting mirror 81 and the substrate 82 are fixed with the screws 83. There is no need. For example, the member serving as a substitute for the metal ring 20 may be one in which a metal thin film is formed on the surface of a resin ring that can withstand the pressure.

(Effect of headlamp 30)
In the headlamp 30, the light emitting unit 7 is sandwiched between the heat conducting member 13 and the transparent plate 19, so that the relative positional relationship between the light emitting unit 7 and the heat conducting member 13 is fixed. Therefore, even when the adhesive has low tackiness between the light emitting unit 7 and the heat conducting member 13 or when a difference in coefficient of thermal expansion occurs between the light emitting unit 7 and the heat conducting member 13, the light emitting unit. 7 can be prevented from peeling off from the heat conducting member 13.

(Other examples of fixed parts)
The fixing part that fixes the relative position of the light emitting part 7 to the heat conducting member 13 does not have to be a plate-like member, and is at least a surface (referred to as a fluorescence emission surface) facing the laser light irradiation surface 7a of the light emitting part 7. What is necessary is just to provide the press-contact surface which press-contacts in part, and the contact surface fixing | fixed part which fixes the relative positional relationship of the said press-contact surface and the heat conductive member 13.

  The relative position between the pressure contact surface and the heat conducting member 13 is fixed, and the pressure contact surface is in pressure contact with the fluorescence emission surface of the light emitting portion 7 (applying a certain pressure to contact the fluorescence emission surface), whereby the light emission portion 7. Can be fixed to the heat conducting member 13.

  FIGS. 9A to 9C are diagrams showing a modification of the fixing portion. For example, as shown in FIG. 9A, when the light emitting unit 7 has a cylindrical shape, the fixing unit has a surface in contact with the fluorescence emission surface of the light emitting unit 7 and is connected (adhered or bonded) to the heat conducting member 13. When the light emitting part 7 is a rectangular parallelepiped or a cube as shown in FIG. 9B, a cylindrical hollow member 21a that is welded) may be a rectangular parallelepiped or a cube. However, in the hollow members 21a and 21b, the surface connected to the heat conducting member 13 is open.

  Moreover, as shown in FIG.9 (c), a part (especially center part) of the surface which contact | connects the fluorescence emission surface of the fixing | fixed part 21c may open. With this configuration, it is possible to prevent the fluorescence emitted from the light emitting unit 7 from being lost by being absorbed by the fixed unit. The fixing portion is preferably a translucent member, but the fixing portion may be formed of a non-translucent substance (for example, metal) as long as the central portion is open.

  Alternatively, a plurality of wires may be used as the fixing portion, and one end portion of these wires may be connected to the light emitting portion 7 and the other end portion may be connected to the heat conducting member 13.

  Further, as shown in FIG. 9D, the light emitting part 7 may be connected to the heat conducting member 13 by the adhesive layer 22 without providing the fixing part 21.

[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.

  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. 10 is a schematic view showing the external appearance of the light emitting unit 210 and the conventional LED downlight 300. FIG. 11 is a cross-sectional view of the ceiling where the laser downlight 200 is installed. FIG. 12 is a cross-sectional view of the laser downlight 200. As shown in FIGS. 10 to 12, 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. 12, 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. 12, 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 portion 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. 10, 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. 12. 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. 13 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. 10, 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. 14 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. 15 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.

  The present invention can be applied to a light-emitting device and a lighting device that have a high luminance and a long service life, particularly a headlamp for a vehicle.

1 Headlamp (light emitting device, vehicle headlamp)
2 Semiconductor laser array (excitation light source)
3 Semiconductor laser (excitation light source)
7 Light Emitting Part 13 Thermal Conductive Member 15 High Thermal Conductive Filler (Heat Conductive Particles)
16 Phosphor particles 17 Inorganic glass (sealing material)
30 Headlamp 200 Laser downlight (light emitting device, lighting device)

Claims (6)

An excitation light source that emits excitation light;
A light emitting unit including a phosphor that emits light by excitation light emitted from the excitation light source,
The light emitting portion is seen containing a thermally conductive particles,
A reflecting mirror for reflecting the light emitted from the light emitting unit;
A heat conduction member that contacts the light emitting unit and receives heat of the light emitting unit;
The reflecting mirror includes a first partial reflecting mirror and a second partial reflecting mirror having a portion near the focal position,
A transparent plate is sandwiched between the first partial reflector and the second partial reflector;
The second partial reflecting mirror keeps the distance between the heat conducting member and the transparent plate constant,
The light emitting device is characterized in that the light emitting portion is sandwiched between the heat conducting member and the transparent plate . The light emitting part is obtained by sealing the phosphor with a sealing material,
The light emitting device according to claim 1, wherein the thermal conductivity of the thermal conductive particles is higher than the thermal conductivity of the sealing material.   The light emitting device according to claim 1, wherein the heat conductive particles have translucency.   The light emitting device according to any one of claims 1 to 3, wherein the thermally conductive particles and the phosphor are dispersed in the light emitting portion in a state of being in contact with each other. Lighting apparatus characterized by comprising a light emitting device according to any one of claims 1-4. Vehicle headlamp, characterized in that it comprises a light-emitting device according to any one of claims 1-4.