JP5425024B2 - Vehicle headlamp - Google Patents

Description

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

  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, in the conventional configuration described above, emphasis is placed on cooling the light emitting unit, and the technical idea of utilizing the heat of the light emitting unit is not disclosed in the above patent document.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a light-emitting device and a vehicle headlamp that can effectively use the heat of the light-emitting portion.

  In order to solve the above problems, a light-emitting device according to the present invention has an excitation light source that emits excitation light, a light-emitting unit that emits light by excitation light emitted from the excitation light source, and heat conduction with the light-emitting unit. A first heat conducting member connected as possible, wherein the first heat conducting member conducts the heat of the light emitting part received by the first heat conducting member to another member for use. It is characterized by being arranged.

  According to the above configuration, when the light emitting unit emits light upon receiving excitation light, a part of the excitation light becomes heat without being converted into fluorescence, and the temperature of the light emitting unit rises. This heat is transmitted to the first heat conducting member connected to the light emitting portion so as to be able to conduct heat, and then conducted to other members for use. For example, it is used for preventing or removing condensation, preventing or thawing freezing, or melting snow.

  Therefore, the heat of the light emitting part can be effectively used, and it is not necessary to consume additional energy for melting snow or the like.

  Moreover, it is preferable that the said 1st heat conductive member is arrange | positioned at the side of the excitation light irradiation surface which is a surface where the said excitation light in the said light emission part is irradiated, and permeate | transmits the said excitation light.

  According to said structure, a 1st heat conductive member is arrange | positioned at the excitation light irradiation surface side of a light emission part, and cools a light emission part by absorbing the heat | fever of a light emission part. Since this 1st heat conductive member is translucent, excitation light can permeate | transmit the said 1st heat conductive member, and can reach | attain a light emission part. Since the excitation light irradiation surface generates the most heat among the light emission units, the light emission unit can be effectively cooled by arranging the first heat conductive member on the excitation light irradiation surface side.

  The heat received by the first heat conducting member is preferably conducted to the reflecting mirror.

  According to said structure, the heat | fever of a light emission part is conducted to a reflective mirror via a 1st heat conductive member, and a reflective mirror is warmed. Therefore, condensation (or freezing) on the reflecting mirror surface can be prevented or removed.

  In addition, a first light transmissive member that is provided in the opening of the reflecting mirror and transmits the fluorescence of the light emitting unit as illumination light is further provided, and the heat received by the first heat conducting member is transmitted to the first light transmissive member. Preferably it is conducted.

  According to said structure, a 1st translucent member is warmed with the heat | fever of a light emission part. The first light transmissive member is provided in the opening of the reflecting mirror and emits the illumination light to the outside of the light emitting device. By heating the first light transmissive member, it is possible to prevent condensation of the first light transmissive member.

  Moreover, the vehicle headlamp provided with the said light-emitting device is also contained in the technical scope of this invention. In this vehicle headlamp, by using the heat of the light emitting section, condensation or prevention, freezing prevention or melting, or snow melting of the vehicle headlamp can be performed.

  The vehicle headlamp includes a second light-transmitting member that is emitted to the outside of the vehicle headlamp by transmitting the illumination light emitted from the light-emitting device, and the heat received by the first heat conducting member. It is preferable to further comprise a second heat conducting member that conducts the light to the second light transmissive member.

  According to said structure, the 2nd light transmission member is provided in the vehicle headlamp, and the illumination light radiate | emitted from the light-emitting device permeate | transmits the 2nd light transmission member, and thereby the vehicle headlamp It is emitted to the outside. The second light transmitting member is connected to the first heat conducting member via the second heat conducting member so as to be able to transfer heat, and the heat of the light emitting unit received by the first heat conducting member is the second heat conducting member. Conducted to the translucent member. Therefore, the second light transmissive member can be warmed by the heat of the light emitting unit.

  Therefore, it is possible to prevent or remove condensation of the second light transmissive member, to prevent or thaw freezing, or to melt snow, and to effectively use the heat of the light emitting unit.

  As described above, the light-emitting device according to the present invention enables excitation light source that emits excitation light, a light-emitting unit that emits light by excitation light emitted from the excitation light source, and heat conduction with the light-emitting unit. A first heat conduction member connected to the first heat conduction member, wherein the first heat conduction member conducts the heat of the light emitting part received by the first heat conduction member to another member and can be used. It is the composition which is.

  Therefore, the heat of the light emitting part can be effectively used, and there is an effect that it is not necessary to separately consume energy for melting snow or the like.

It is sectional drawing which shows the structure of the headlamp which concerns on one Embodiment of this invention. It is a figure which shows the structure where the light emission part with which the said headlamp is equipped, and the heat conductive member are adhere | attached by the contact bonding layer. It is sectional drawing which shows a preferable example of a diffusing agent. (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. (A)-(c) is a figure which shows the modification of a fixing | fixed part. It is sectional drawing which shows the example of a change of the said light emission part. 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.

[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 streetlight, and a traffic light.

  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. 1 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 unit 7, a reflecting mirror 8, a transparent plate (first translucent member). ) 9, a housing 10, an extension 11, a lens (second translucent member) 12, a heat conducting member (first heat conducting member) 13, and an adhesive layer 15. The adhesive layer 15 functions as a gap layer that fills the gap between the heat conducting member 13 and the light emitting unit 7. Further, as shown in FIG. 2, the adhesive layer 15 includes a diffusing agent 16. FIG. 2 is a view showing a structure in which the light emitting unit 7 and the heat conducting member 13 are bonded by the adhesive layer 15.

(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.

  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 does not necessarily have to be a bundle of a plurality of optical fibers (that is, a configuration including a plurality of emission end portions 5a), and there may be one emission end portion 5a.

  Further, the emission end portion 5a may be in contact with the laser light irradiation surface 7a, or may be disposed at a slight interval. In particular, when the emission end 5a is spaced from the laser light irradiation surface 7a, the laser light emitted from the emission end 5a and spreading in a conical shape is irradiated to the laser light irradiation surface 7a. It is preferable to be determined as follows.

(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 arrangement | positioning with respect to the laser beam irradiation surface 7a of the light emission part 7 of the light emission part 5a can be changed easily. Therefore, the emission end portion 5a can be arranged along the shape of the laser light irradiation surface 7a of the light emitting portion 7, and the laser light can be mildly irradiated over the entire surface of the laser light irradiation surface 7a of the light emitting portion 7. .

  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. That is, the positional relationship between the incident end portion 5b and the emitting end portion 5a can be easily changed, and the positional relationship between the semiconductor laser 3 and the light emitting portion 7 can be easily changed. The degree of freedom can be increased.

  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. However, it is preferable to provide the ferrule 6 in order to accurately fix the relative position of the emission end portion 5a to the laser light irradiation surface 7a.

(Light Emitting Unit 7)
(Composition of light-emitting part 7)
The light emitting part (wavelength converting member) 7 emits light upon receiving the laser light emitted from the emission end part 5a, and includes a phosphor that emits light upon receiving the laser light. Specifically, the light emitting unit 7 is a phosphor in which a phosphor is dispersed inside a silicone resin as a phosphor holding substance (sealing material). The ratio of silicone resin to phosphor is about 10: 1. In addition, the light emitting unit 7 may be formed by pressing a fluorescent material. The phosphor holding substance is not limited to a resin material such as a silicone resin, and may be so-called organic-inorganic hybrid glass or inorganic glass.

  The phosphor is, for example, an oxynitride type, and any one or more of phosphors emitting blue, green, and red light are dispersed in a silicone resin. 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.

(Type of phosphor)
The light emitting part 7 preferably contains 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 emission color can be changed by the quantum size effect by changing the particle diameter to nanometer size. It is a point that 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.

  Therefore, it can suppress more that the light emission part 7 deteriorates (discoloration or deformation | transformation) with a heat | fever. Thereby, when using the light emitting element with a high light output as a light source, it can suppress more that the lifetime of a light-emitting device becomes short.

(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 of the phosphor holding substance 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 thin, the heat dissipation effect to the heat conducting member 13 is also enhanced. However, if the light emitting portion 7 is made too thin, there is a possibility that the laser light is not converted into fluorescence and emitted outside, and absorption of excitation light by the phosphor From this point of view, the thickness of the light emitting part is preferably at least 10 times the particle size of the phosphor. 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.

  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.

  Furthermore, 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 suppress the reflection of the laser beam, the laser beam irradiation surface 7a is preferably a plane perpendicular to the optical axis of the laser beam.

  Further, as shown in FIGS. 1 and 2, the light emitting unit 7 is fixed to the surface of the heat conducting member 13 opposite to the side irradiated with the laser light by an adhesive layer 15.

(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 is provided in the opening of the reflecting mirror 8 and transmits the fluorescence of the light emitting unit 7 as illumination light. 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. By sandwiching the light emitting part 7 between the heat conducting member 13 and the transparent plate 9, the position of the light emitting part 7 can be more reliably fixed even when the adhesive force of the adhesive layer 15 is weak.

  At this time, if the transparent plate 9 has a higher thermal conductivity than the light emitting portion 7 (for example, glass when the sealing material constituting the light emitting portion is a silicone resin), the transparent plate 9 The cooling effect of the light emitting part 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, considering the case where the semiconductor laser 3 has failed, it is preferable to install the semiconductor laser 3 at a position where it can be easily replaced. 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. That is, the lens 12 is a translucent member that is emitted to the outside of the vehicle headlamp by transmitting the fluorescence of the light emitting unit 7 as illumination light.

(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). Specifically, the light emitting section 7 and the heat conducting member 13 are bonded together by an adhesive layer (gap layer) 15 as shown in FIG. FIG. 2 is a diagram illustrating a state where the light emitting unit 7 is bonded to the heat conducting member 13 by the adhesive layer 15.

  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 connected to the reflecting mirror 8. That is, the heat conducting member 13 is disposed so that the heat of the light emitting unit 7 received can be conducted to other members and used.

  The heat conducting member 13 has such a shape and connection form, and conducts heat generated from the light emitting unit 7 to the reflecting mirror 8 while holding the minute light emitting unit 7 at the light emitting unit fixing position. With this configuration, the reflecting mirror 8 is warmed, and condensation on the surface of the reflecting mirror 8 is prevented or removed.

  In addition, since the heat conductive member 13 is warmed by the light emission part 7, even when the heat conductive member 13 itself condenses, the dew condensation (cloudy) is removed.

  In order to efficiently transmit the heat of the heat conducting member 13 to the entire reflecting mirror 8, the reflecting mirror 8 is preferably formed of metal. However, when the reflecting mirror 8 is formed of resin in order to reduce the weight, the heat conducting member 13 and the heat are formed on the surface of the reflecting mirror 8 in order to transmit the heat of the heat conducting member 13 to the entire surface of the reflecting mirror 8. An electrically connected metal wire may be provided.

  In order to conduct the heat of the light emitting unit 7 efficiently, 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. 2 (a first surface 13a located on the laser beam 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.

(Adhesive layer 15)
The adhesive layer 15 is an adhesive layer that fills the gap between the heat conducting member 13 and the laser light irradiation surface 7a. The size of the phosphor contained in the light emitting part 7 is about 1 to 20 μm in diameter. If the light emitting part 7 is brought into contact with the surface of the thermally conductive member 13 made of sapphire, for example, a relatively large gap is generated. . By providing the adhesive layer 15 between the heat conducting member 13 and the laser light irradiation surface 7 a of the light emitting unit 7, this gap can be filled. This substantially increases the contact area between the heat conducting member 13 and the laser light irradiation surface 7a. Therefore, the heat absorption efficiency of the heat conducting member 13 can be increased. At this time, if the adhesive layer 15 has a thermal conductivity equal to or higher than that of the light emitting portion 7, the heat absorption efficiency of the heat conducting member 13 can be further increased.

  The adhesive layer 15 preferably has flexibility (or viscosity) that absorbs the difference in thermal expansion coefficient between the light emitting unit 7 and the heat conducting member 13. When the light emitting unit 7 generates heat, the light emitting unit 7 and the heat conducting member 13 have different coefficients of thermal expansion. Therefore, the light emitting unit 7 may be separated from the heat conducting member 13 due to the difference in the coefficient of thermal expansion.

  If the adhesive layer 15 has flexibility (or viscosity) that absorbs the difference in thermal expansion coefficient with the heat conducting member, the light emitting unit 7 is peeled off from the heat conducting member 13 due to heat generated by the light emitting unit 7. Can be prevented.

  As an example of the adhesive layer 15, mention may be made of Epicacolle EP433, a visible light polymerization type optical adhesive made by Adel. Although the thermal conductivity of this product is not disclosed, it is considered to be about 0.1 to 0.3 W / mK because it is an acrylic adhesive.

  The thickness of the adhesive layer 15 (thickness between the heat conducting member 13 and the laser light irradiation surface 7a) is preferably 1 μm or more and 30 μm or less. By setting the thickness of the adhesive layer 15 to 1 μm or more and 30 μm or less, even when the thermal conductivity of the adhesive layer 15 is lower than the thermal conductivity of the light emitting unit 7, the thermal resistance of the adhesive layer 15 can be reduced, and the light emitting unit 7 The heat generated in can be efficiently transferred to the heat conducting member 13 through the adhesive layer 15. For example, when the thermal conductivity of the adhesive layer 15 is 1 W / mK and the thickness of the adhesive layer 15 is 0.1 mm, the thermal conductivity of the adhesive layer 15 is 0.2 W / mK, and the adhesive layer 15 As a result, the thermal resistance is the same when the thickness is 20 μm (= 0.02 mm).

(Diffusion agent 16)
The adhesive layer 15 may include a diffusing agent 16. The laser light is coherent light, and if it is radiated to the outside as it is without being converted or diffused into fluorescence in the light emitting unit 7, there is a possibility of harming the human body. By including the diffusing agent 16 in the adhesive layer 15, the laser light emitted from the optical fiber 5 is diffused.

  Therefore, even if a situation occurs in which the laser light is not completely converted or diffused into the fluorescent light in the light emitting unit 7, the possibility of coherent light leaking to the outside is reduced by previously diffusing the laser light with the diffusing agent 16. it can.

Preferred materials for the diffusing agent 16 include SiO ₂ beads (true spherical shape, particle size: several nm to several μm, mixed in 0.1% to several% adhesive layer 15), Al ₂ O ₃ beads, diamond beads, and the like. Can be mentioned. If the amount of the diffusing agent 16 is too large, the amount of the laser light reaching the light emitting portion 7 is reduced. Therefore, the amount of the diffusing agent 16 is preferably about 1 mg to 30 mg per 1 g of the adhesive layer 15.

In addition, the effect which improves the heat conductivity of the contact bonding layer 15 is also acquired by mixing such an inorganic transparent body. SiO ₂ is 1.38 W / mK, which is higher than that of acrylic resin. If diamond particles are used, the thermal conductivity is as high as 800 to 2000 W / mK. As a result, the thermal conductivity of the adhesive layer 15 is greatly increased. Can be improved.

(Combination of material of gap layer and light emitting part 7)
As described above, the adhesive layer 15 preferably has a thermal conductivity equal to or higher than that of the light emitting portion 7. Since the adhesive layer 15 includes an adhesive among the gap layers of the present invention, an example of the material thereof will be described using the expression of the superordinate concept of the gap layer.

  An example of the material of the gap layer and the light emitting portion 7 is shown in Table 1. In some of these examples, in order to increase the thermal conductivity of the gap layer, a high thermal conductive filler (high thermal conductivity additive) made of the same material as that of the diffusing agent 16 is included in the gap layer. The high thermal conductive filler is a translucent particle containing a material having high thermal conductivity.

  In the following description, a high thermal conductivity filler having a higher thermal conductivity than a resin is referred to as a high thermal conductivity filler A, and a high thermal conductivity filler A having a higher thermal conductivity than glass is referred to as a high thermal conductivity filler B. Called.

Examples of the material belonging to the high thermal conductive filler A include SiO ₂ beads, Al ₂ O ₃ beads, diamond beads and the like. Examples of the material belonging to the high thermal conductive filler B include Al ₂ O ₃ beads and diamond beads.

  For example, if the gap layer is formed of an acrylic adhesive, and a resin-based material (for example, epoxy, silicone, HBG (HyBrid Glass)) is used as the sealing material for the light-emitting portion 7, the gap layer The thermal conductivity is equal to that of the light emitting unit 7.

  Further, examples of the combination in which the thermal conductivity of the gap layer is higher than the thermal conductivity of the light emitting unit 7 include the following two types.

  (1) When the sealing material of the light emitting portion 7 is a resin material, an acrylic adhesive, an acrylic adhesive kneaded with a high thermal conductive filler A, a glass paste (typically a low melting point) as a gap layer Glass paste using glass), or glass paste kneaded with the high thermal conductive filler A or B can be used.

In this case, SiO ₂ (silica) beads having a thermal conductivity of about 1 W / mK and Al ₂ O having a thermal conductivity of about 20 to 40 W / mK are used as the high thermal conductivity filler A. ₃ (sapphire) beads, diamond beads having a thermal conductivity of about 1000 to 2000 W / mK can be used.

  (2) When the sealing material of the light emitting portion 7 is inorganic glass, as the gap layer, a glass paste using a low melting point glass or the like, or a glass paste in which a high thermal conductive filler B is mixed can be used.

  Even if low melting point glass is used, in order to melt and bond, it is necessary to heat at least about 400 ° C. or higher, so the high thermal conductive filler melts at the melting temperature of the glass paste used, It is required not to be altered.

Since the melting point of SiO ₂ beads (silica), which is an example of the above-mentioned high thermal conductive filler, is 1713 ° C., the melting point of Al ₂ O ₃ beads is 2030 ° C., and the melting point of diamond is 3550 ° C. There is no melting or alteration.

  In any case of (1) to (2), a high thermal conductive filler to be mixed in the gap layer may be selected so that the thermal conductivity of the gap layer is higher than the thermal conductivity of the light emitting part.

  However, the thermal conductivity of the gap layer depends not only on the material of the high thermal conductive filler to be mixed but also on its concentration. 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 gap layer may be adjusted by adjusting the material and amount of the high thermal conductive filler to be mixed in the gap layer.

  A plurality of types of high thermal conductive fillers may be mixed in the gap layer.

(About thermal resistance)
In the above description, the material of each member has been described focusing on the thermal conductivity, but the present invention can also be understood from the viewpoint of thermal resistance.

  The thermal resistance in this specification is a numerical value represented by the following formula (1) and indicating the difficulty of heat transfer.

Thermal resistance = (1 / thermal conductivity) · (length of heat dissipation path / heat dissipation cross-sectional area) (1)
If the other parameters are the same, the thermal resistance decreases as the thermal conductivity increases. Therefore, increasing the thermal conductivity of the light-emitting portion 7 and the gap layer decreases the thermal resistance of these members.

  As a method for reducing the thermal resistance, in addition to increasing the thermal conductivity, a method of increasing the heat radiation area (joint area with other members) or reducing the thickness of the member can be used.

  The thermal resistance may be a numerical value indicating difficulty in transferring heat, and a concept of thermal resistance other than that defined by the equation (1) may be applied to the present invention.

(Shape of diffusing agent 16)
In the above description, SiO ₂ beads and the like are given as examples of the high thermal conductive filler. However, the high thermal conductive filler does not have to be spherical, and may be rod-shaped or indefinite. However, from the viewpoint of controlling the thickness of the gap layer, a true sphere having a uniform diameter is preferable.

  FIG. 3 is a cross-sectional view showing a preferred example of the diffusing agent 16. As shown in the figure, the diffusing agent 16 is a substantially spherical (preferably true sphere) particle having a predetermined diameter, and maintains a constant distance between the light emitting portion 7 and the heat conducting member 13. The heat conducting member 13 and the light emitting unit 7 are brought into contact with each other to conduct heat of the light emitting unit 7 to the heat conducting member 13.

  The diffusing agent 16 is preferably present only in one layer between the heat conducting member 13 and the light emitting portion 7, and a gap material (adhesive or glass paste or the like) is filled between the diffusing agents 16. By providing such a diffusing agent 16, even if the gap material is made of a material such as an acrylic adhesive having a low thermal conductivity, the heat of the light emitting portion 7 can be efficiently conducted to the heat conducting member 13. Can do.

  Note that the diffusing agent 16 may form a plurality of layers as long as the distance between the heat conducting member 13 and the light emitting unit 7 is kept constant.

(Structure of semiconductor laser 3)
Next, the basic structure of the semiconductor laser 3 will be described. FIG. 4A schematically shows a circuit diagram of the semiconductor laser 3, and FIG. 4B 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.

(Example of changing the fixed part)
In the above description, the transparent plate 9 is taken as an example of the fixing unit that fixes the relative position of the light emitting unit 7 to the heat conducting member 13. However, the fixing unit does not have to be the transparent plate 9. A pressure contact surface that is in pressure contact with at least a part of a surface (referred to as a fluorescence emission surface) facing the laser light irradiation surface 7a, and a contact surface fixing portion that fixes a relative positional relationship between the pressure contact surface and the heat conducting member 13. It only has to be provided.

  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. 5A to 5C are diagrams showing a modification of the fixing portion. For example, as shown in FIG. 5A, as the fixing portion, when the light emitting portion 7 has a cylindrical shape, the fixing portion has a surface in contact with the fluorescence emitting surface of the light emitting portion 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. 5B, a rectangular hollow or a hollow member 20b having a rectangular parallelepiped or a cube may be used. However, in the hollow members 20a and 20b, the surface connected to the heat conducting member 13 is open.

  Moreover, as shown in FIG.5 (c), a part (especially center part) of the surface which contact | abuts the fluorescence emission surface of the fixing | fixed part 20c 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.

(Modification example of heat conduction member 13)
The heat conducting member 13 may be connected to the transparent plate 9 instead of the reflecting mirror 8. With this configuration, the heat of the light emitting unit 7 is conducted to the transparent plate 9 through the heat conducting member 13. If the transparent plate 9 is made of glass, heat can be efficiently received from the heat conducting member 13.

  The connection mode between the heat conducting member 13 and the transparent plate 9 is not particularly limited. For example, the heat conductive member 13 may be formed as a three-dimensional shape having a hollow shape such as a cylindrical shape or a cube, and the heat conductive member 13 may be connected to the transparent plate 9 so as to cover the light emitting portion 7. That is, the heat conducting member 13 is in contact with the laser light irradiation surface of the light emitting unit 7 so as to be able to conduct heat and transmits the laser light, and the relative relationship between the excitation light transmitting surface and the transparent plate 9. An excitation light transmitting surface fixing portion that fixes the positional relationship may be included.

(Modification example of the light emitting unit 7)
FIG. 6 is a cross-sectional view showing a modified example of the light emitting unit 7. As shown in FIG. 6, a reflective film 17 may be formed on the side surfaces of the light emitting unit 7 and the adhesive layer 15. The reflective film 17 is a light-reflective film that covers at least a part of the outer surface of the adhesive layer 15 (the surface not in contact with the light emitting unit 7 and the heat conducting member 13). For example, a metal thin film (for example, an aluminum thin film) ).

  Since the adhesive layer 15 includes the diffusing agent 16, the laser light is diffused by the diffusing agent 16, so that the laser light (referred to as stray light) leaks from the side surface of the adhesive layer 15 without going to the light emitting portion 7. Occur. By providing the reflective film 17 on the side surface of the adhesive layer 15, the stray light is reflected by the reflective film 17 and stays inside the adhesive layer 15. Therefore, the utilization efficiency of laser light can be increased.

  The reflective film 17 only needs to cover at least the side surface of the adhesive layer 15, and it is not always necessary to cover the side surface of the light emitting unit 7. However, the cooling effect of the light emitting unit 7 by the reflective film 17 can be obtained by covering the side surface of the light emitting unit 7 with the reflective film 17. This effect can be enhanced by forming the reflective film 17 with a material having higher thermal conductivity than the light emitting portion 7.

  As shown in FIG. 2, the reflective film 17 may be provided not only on the side surface of the adhesive layer 15 but also on the side surface of the light emitting unit 7. With this configuration, the cooling effect of the light emitting unit 7 can also be obtained by the reflective film 17. This effect can be enhanced by forming the reflective film 17 with a material having higher thermal conductivity than the light emitting portion 7.

  Further, the light emitting unit 7 may be brought into contact with the heat conducting member 13 with a physical force. In that case, it is not always necessary to provide the adhesive layer 15.

(Effect of headlamp 1)
When the light emitting unit 7 is excited with high-power laser light, the light emitting unit 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 (for example, silicone resin) surrounding the phosphor. 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. It is considered that the material surrounding the phosphor is deteriorated by this heat.

  In the headlamp 1, the heat conducting member 13 is disposed on the excitation light irradiation surface side of the light emitting unit 7, and cools the light emitting unit 7 by absorbing the heat of the light emitting unit 7. Since the excitation light irradiation surface of the light emission unit 7 generates the most heat, the light emission unit 7 can be effectively cooled by thermally connecting the heat conducting member 13 to the excitation light irradiation surface.

  Thereby, the lifetime of the headlamp as an ultra-bright light source using laser light as an excitation light source can be extended, and its reliability can be improved.

  The heat received by the heat conducting member 13 from the light emitting unit 7 is used for preventing or removing condensation in the headlamp 1 (particularly the surface of the reflecting mirror 8), or preventing or melting the freezing.

  Therefore, the heat of the light emitting unit 7 can be effectively used, and it is not necessary to separately consume energy for preventing condensation and the power consumption of the headlamp 1 can be reduced.

  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.

  A sapphire plate having a thickness of 0.5 mm (thermal conductivity: 42 W / mK) is used as the heat conductive member 13, and the visible light polymerization type optical adhesive Epicacoll EP433 made by Adel is used for the heat conductive member 13. The light emitting part 7 was adhered using the adhesive layer 15. 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. Furthermore, since the heat dissipation to the heat conductive plate is improved by reducing the thickness of the heating element from 1 mm, the temperature rise of the heating element can be further reduced.

  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 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, organic-inorganic hybrid glass or inorganic glass is preferable, and when using a silicone resin, a thermal simulation is strictly performed and temperature rise is suppressed to about 150 ° C. or less. Is preferred. In the case of organic-inorganic hybrid glass, the temperature is allowed to be about 250 ° C. to about 300 ° C. Moreover, if it is inorganic glass, even if it is 500 degreeC or more, there is no problem.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIG. In addition, about the member similar to Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted. FIG. 8 is a schematic view showing a configuration of a headlamp 30 according to another embodiment of the present invention.

  In the headlamp 30 of the present embodiment, one end portion of the heat conducting member 13 connected to the reflecting mirror 8 extends from the reflecting mirror 8, and a heat pipe (second heat conducting member) is connected to the end portion. ) 14 is connected.

  The heat pipe 14 is obtained by enclosing a working fluid in a metallic pipe having high thermal conductivity such as copper. In order to move the working fluid quickly by capillary action, a capillary tube may be provided inside the heat pipe 14.

  The other end of the heat pipe 14 is connected to the lens 12 so that heat can be conducted to the lens 12 through an opening provided in the extension 11.

  The heat pipe 14 transfers the heat of the light emitting unit 7 received by the heat conducting member 13 to the lens 12, warms the lens 12 and radiates the heat of the light emitting unit 7 to the outside air.

  The lens 12 is directly exposed to the outside air, and snow may adhere to the lens 12 in a cold region. In the headlamp 30, since the lens 12 is warmed by the heat of the light emitting unit 7, snow attached to the lens 12 can be melted. Although snow attached to the lens 12 can be melted by using another heat source, energy can be saved by using the heat of the light emitting unit 7.

  The heat conductive member that transmits the heat of the heat conductive member 13 to the lens 12 is not limited to a heat pipe, and may be, for example, a metallic thin wire.

(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 7a Laser light irradiation surface (excitation light irradiation surface)
8 Reflector 9 Transparent plate (first translucent member)
12 Lens (second translucent member)
13 heat conduction member 14 heat pipe (second heat conduction member)
30 Headlamp (light emitting device, vehicle headlamp)

Claims (2)

An excitation light source that emits excitation light;
A light emitting unit that emits light by excitation light emitted from the excitation light source;
A first heat conducting member connected to the light-emitting part so as to allow heat conduction;
The first heat conducting member is disposed so that the heat of the light emitting part received by the first heat conducting member can be conducted to other members and used.
The first heat conducting member is disposed on the side of the excitation light irradiation surface that is the surface irradiated with the excitation light in the light emitting unit, and transmits the excitation light.
The heat received by the first heat conducting member is conducted to the reflecting mirror,
A gap layer that fills a gap between the first heat conducting member and the light emitting unit;
The gap layer is seen containing a thermally conductive particles,
The thermally conductive particles have a predetermined diameter and form a layer, and the layer comes into contact with the light emitting unit and the first heat conducting member, thereby forming the light emitting unit and the first heat conducting member. A vehicle headlamp equipped with a light emitting device that maintains a constant distance between ,
A second translucent member that emits the illumination light emitted by the light emitting device to the outside of the vehicle headlamp;
A vehicle headlamp, further comprising: a second heat conducting member that conducts heat received by the first heat conducting member to the second light transmissive member.   The vehicle headlamp according to claim 1, wherein the gap layer is an adhesive layer or a glass paste.