JP2010080364A - Lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system having improved radiation effects by shutting off heat from the outside and emitting only internal heat to the outside, even when subjected to heat radiation from an external heat source to a radiation plane. <P>SOLUTION: The lighting system includes a light source as a heating source, and a casing 1 storing the light source. To the surface of the casing 1, an emission rate improving means (at least one of machining work, chemical conversion treatment and coating) is applied for improving an emission rate in an infrared region. Then, a material (a multilayered dielectric optical thin film 2) is provided thereon all over for controlling spectral reflectance to reflect electromagnetic components on the short wavelength side rather than the wavelength side where a radiation spectrum issued from the casing 1 is maximum. Thus, the radiation from an external heating element (the external heat source) 5 is shut off and heat from an internal heat source is selectively emitted to the outside. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an illuminating device that efficiently releases heat from a light source to enhance a heat dissipation effect.

  In a lighting device using a light bulb as a light source, most of the input power is emitted as infrared rays, that is, radiant heat, so that the temperature rise of the housing inevitably occurs, and solving this problem is a technical problem. It was one.

  Thus, Patent Document 1 proposes a structure in which a large number of air holes are provided in the housing, and Patent Document 2 proposes a structure in which a film having a high heat dissipation property is attached to the housing. Further, Patent Document 3 proposes a structure in which a ring-shaped heat sink is provided at the base portion, and Patent Document 4 proposes a structure in which a heat pipe is wound around the casing.

  By the way, in recent years, application products for lighting use have been developed along with higher output of LEDs. However, in LEDs, more than half of the input power becomes the heat of the semiconductor itself, so the problem of heat dissipation is a more important technology. It becomes a subject.

  Regarding the heat dissipation technology for LEDs for lighting applications, Patent Document 5 proposes a structure including a heat sink, Patent Document 6 proposes a technique using a resin case as a heat dissipation means, and Patent Document 7 discloses an air cooling fan for the heat sink. Additional configurations have been proposed.

  On the other hand, technological development for efficiently radiating heat has been actively conducted. In particular, in the temperature region of 100 ° C. or higher, the radiation of the three forms of heat transfer occupies most of the heat transfer. Therefore, increasing the emissivity is effective as a heat dissipation means. Conventionally, matte black paint, etc., has been developed that can achieve a heat dissipation effect simply by applying a black anodized aluminum heat sink.

  On the roof of a house, sunlight during the daytime causes the indoor temperature to rise through the roofing material, and particularly in summer, it affects the cooling efficiency. For this reason, Patent Document 8 proposes a thermal barrier paint having an excellent thermal barrier effect.

  Furthermore, a technique for solving the problem due to heat generation of the light source with a functional thin film has been developed, and Patent Document 9 proposes a cold mirror. This cold mirror selectively transmits infrared rays from a light source to escape to the outside and reflects only necessary visible light, and is used exclusively for projection applications.

By the way, the technology relating to the reflection of light is applied to improve the visibility of road signs at night. Patent Document 10 proposes a structure using minute glass beads, and Patent Document 11 discloses a recursion obtained by a texture structure. Techniques relating to reflection are disclosed, in which the particle size and refractive index are optimized for visible light.
JP-A-9-139111 Japanese Patent Laid-Open No. 11-111037 JP 2002-175721 A JP 2003-288806 A JP 2000-031546 A JP 2002-299700 A JP 2008-103195 A JP 2003-261828 A JP 2007-328991 A JP-A-5-263015 JP 2006-322313 A

  When an LED is used as a light source, the LED has a longer life than a light bulb, and is therefore preferably used in an environment with a low maintenance frequency. It is easy to imagine being exposed to harsh environments.

  By the way, in the structure of the conventional lighting device, when the temperature of the external air is higher than the surface temperature of the casing in the heat dissipation path from the casing to the external air, which is the final stage of the heat dissipation path, or the surface of the casing is When receiving radiant heat from another external heat source, heat cannot be radiated from the casing on the low temperature side to the external air on the high temperature side in accordance with the second law of thermodynamics. Therefore, simply improving the emissivity of the housing surface also increases the absorption rate of radiant heat from the external heat source at the same time, and is not a fundamental solution.

  The present invention has been made in view of the above problems, and the intended process is to cut off the heat from the outside and only the internal heat to the outside even when the heat radiation surface receives heat radiation from an external heat source. It is providing the illuminating device which can acquire a high heat dissipation effect by radiating | emitting toward.

  In order to achieve the above object, an invention according to claim 1 is a lighting device including a light source that is a heat source and a housing that houses the light source, and radiation that increases the emissivity of the infrared region on the surface of the housing. By providing a rate improving means, and by providing a material over which the spectral reflectance is controlled so as to reflect an electromagnetic wave component on the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the housing is maximized, It is characterized by blocking radiation from an external heat source and selectively radiating heat from an internal heat source to the outside.

  According to a second aspect of the present invention, in the first aspect of the present invention, the emissivity of the housing surface is reduced to 0 by applying at least one of machining, chemical conversion or coating to the housing surface as the emissivity improving means. .8 or more.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein a multilayer dielectric optical thin film is adhered to the surface of the casing, and a cutoff wavelength is emitted from the casing in the spectral transmittance of the multilayer dielectric optical thin film. It is characterized by reflecting an electromagnetic wave component on the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the casing is maximized by adjusting to the shorter wavelength side than the wavelength at which the emitted radiation spectrum is maximized.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the casing surface is covered with a retroreflective material, and the particle size and refractive index in the retroreflective process are emitted from the casing. Control is performed so as to reflect an electromagnetic wave component on a shorter wavelength side than the wavelength having the maximum spectrum.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the light source is constituted by an LED.

  According to the present invention, by using a technology for forming irregularities on the surface of the casing by enlarging the surface area to increase the surface area, a chemical conversion treatment represented by black alumite treatment and a high emissivity technology represented by matte black paint. The heat radiation from the surface of the casing is increased.

  In the present invention, when the housing surface receives radiant heat from an external heat source and there is a temperature difference between the housing surface and the external heat source, the peak wavelength of each radiation spectrum due to the temperature difference is different. .

  Therefore, the present invention controls the reflection of the electromagnetic wave component on the short wavelength side from the wavelength at which the radiation spectrum emitted from the casing has the maximum spectral reflectance on the surface of the casing on which the high emissivity means is applied. By applying or adhering a material, for example, a multilayer dielectric optical thin film that protects other members from infrared rays emitted from a light source or a retroreflective material that improves visibility by reflecting visible light, etc., to an external heat source The heat from the internal heat source is selectively radiated to the outside. When bonding a multilayer dielectric thin film to the housing surface, using an adhesive such as silicon or epoxy may affect the wavelength selectivity of the optical properties of the adhesive itself. Vapor deposition is also desirable.

  The multilayer dielectric thin film so that the heat radiation from the external heat source is located on the shorter wavelength side than the cutoff wavelength of the multilayer dielectric thin film, and the heat radiation from the housing is located on the longer wavelength side than the cutoff wavelength. By adjusting the film thickness, the electromagnetic wave component on the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the housing becomes maximum can be reflected.

  In addition, according to the present invention, the surface of the casing is covered with a material having recursive reflectivity, the particle size of the retroreflective material is shorter than the wavelength at which the maximum value of the radiation spectrum of the casing, and the radiation of the external heat source By selecting a material having a refractive index that is longer than the maximum wavelength of the spectrum and has a reflex reflection over a wide angle in the wavelength band where the radiation spectrum of the external heat source is maximum. The electromagnetic wave component on the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the body is maximum can be reflected.

  As a result of the above, according to the present invention, even when heat radiation from the external heat source is received on the heat radiating surface of the lighting device, by blocking the heat from the outside and radiating only the internal heat toward the outside, A high heat dissipation effect can be obtained.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, a heat dissipation structure on the surface of a housing of a conventional lighting device will be described with reference to FIG.

  In the heat dissipation structure on the housing surface of the conventional lighting device shown in FIG. 1, simply improving the surface emissivity of the housing 101 is to efficiently convert the heat transfer 102 from the internal heat source into the heat radiation 103 to the outside. However, at the same time, the absorptance of the heat radiation 105 from the external heat source 104 is also increased at the same time, leading to heat input 106 into the housing 101. As a result, the subtraction between the heat radiation 103 from the surface of the housing 101 and the heat radiation 105 from the external heat source 104 is negative, and does not lead to a fundamental solution.

  Therefore, in the present invention, when the housing surface receives radiant heat from an external heat source and there is a temperature difference between the housing surface and the external heat source, the peak wavelength of each radiation spectrum due to the temperature difference is different. Paying attention, the following heat dissipation structure was adopted.

  That is, in an illuminating device including a light source that is a heat source and a housing that houses the light source, emissivity improving means for increasing the emissivity in the infrared region is applied to the surface of the housing, and the spectral reflectance is further provided thereon. By covering the entire surface with a material that controls to reflect the electromagnetic wave component on the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the housing is maximum, the radiation from the external heat source is blocked and the Heat was selectively radiated to the outside.

  Here, the emissivity improving means is at least one of machining, chemical conversion or coating on the surface of the casing, and by applying this, the emissivity of the casing surface is set to 0.8 or more.

  In addition, a multilayer dielectric optical thin film is adhered to the surface of the casing that has been subjected to high emissivity means, and the radiation spectrum emitted from the casing at the cutoff wavelength in the spectral transmittance of the multilayer dielectric optical thin film is maximized. By adjusting to the shorter wavelength side than the wavelength, the electromagnetic wave component on the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the casing becomes maximum is reflected.

  Alternatively, the case surface is covered with a retroreflective material, and the particle size and refractive index in the process of retroreflection are reflected to reflect the electromagnetic wave component on the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the case is maximum. It was controlled to do.

  And in this invention, the light source was comprised by LED.

Next, a case where a multilayer dielectric optical thin film is bonded to the surface of the casing on which high emissivity means has been applied and a case where the multilayer dielectric optical thin film is covered with a retroreflective material will be described.
(1) When using a multilayer dielectric optical thin film:
The heat dissipation structure on the housing surface in this case is schematically shown in FIG.

As shown in FIG. 2, in the two-layer structure of the casing 1 and the multilayer dielectric optical thin film 2, by controlling the multilayer dielectric optical thin film 2, the heat transfer 3 from the internal heat source 3 The radiant heat 4 passes through the multilayer dielectric optical thin film 2 because it is located on the longer wavelength side than the cutoff wavelength. On the other hand, since the radiant heat 6 from the external heat source 5 is located on the shorter wavelength side than the cutoff wavelength of the multilayer dielectric optical thin film 2, the heat reflection 7 by the multilayer dielectric optical thin film 2 occurs. As a result, only the electromagnetic wave component on the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the housing 1 is maximized is selectively reflected.
(2) When using a retroreflective material:
The heat dissipation structure on the housing surface in this case is schematically shown in FIG.

  As shown in FIG. 3, in the two-layer structure of the housing 1 and the retroreflective member 8, by controlling the particle size of the retroreflective member 8, the heat transfer 3 from the internal heat source causes the surface of the housing 1 to Since the wavelength of the radiant heat 4 is longer than the particle size of the retroreflective member 8, it is transmitted therethrough. On the other hand, since the wavelength of the radiant heat 6 from the external heat source 5 is shorter than the particle size of the retroreflective member 8, retroreflection 9 occurs. As a result, only the electromagnetic wave component on the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the housing 1 is maximized is selectively reflected.

  In the cases (1) and (2) above, FIG. 4 shows a spectrum image of selective reflection. Under the conditions to be applied, it is desirable to set a selective reflection threshold at a wavelength at which the radiation spectrum of the housing surface and the external heat source just cross over. In addition, the effect of this invention becomes large, so that both temperature difference is large (for example, when an external heat source is the sun of 6000K).

  A basic embodiment using test pieces will be described below.

  The test piece was made in the following manner, imitating the case wall surface.

  That is, an aluminum (Al1050) substrate having a size of 50 mm × 50 mm and a thickness of 1 mm is provided with emissivity improvement / selective reflection means, respectively. In addition, the back side is the aluminum base which does not process anything.

  A matte black paint with an emissivity of 0.98 was applied to the surface of the test piece as an emissivity improving means. Due to the characteristics of the paint, the surface had minute irregularities, and it was in the same state as roughened by mechanical polishing. Further, glass beads having an average particle diameter of 7 to 8 μm and a refractive index of about 1.5 were applied as selective reflection means using an acrylic paint as a binder. The reflectance in the selective reflection region was 0.75.

  In Example 1, a pearl paint containing fine acrylic pieces having an average particle diameter of 7 to 8 μm was applied by spraying instead of the glass beads of the selective reflection means. The reflectivity in the selective reflection region was 0.7.

  In Example 1, a multilayer dielectric optical thin film controlled to have a cutoff wavelength of 7 to 8 μm was deposited instead of the glass beads of the selective reflection means. The reflectance in the selective reflection region was 0.8.

  In Example 1, black alumite treatment with an emissivity of 0.95 was performed instead of the matte black paint of the emissivity improving means. The selective reflection means is the same as that of the first embodiment with glass beads.

  In Example 4, pearl paint containing fine acrylic pieces having an average particle diameter of 7 to 8 μm was applied by spraying instead of the glass beads of the selective reflection means.

  In Example 4, a multilayer dielectric optical thin film controlled to have a cutoff wavelength of 7 to 8 μm was deposited instead of the glass beads of the selective reflection means.

  In Example 1, a glossy black paint having an emissivity of 0.9 was applied instead of the matte black paint of the emissivity improving means. The selective reflection means is the same as that of the first embodiment with glass beads.

  In Example 7, instead of the glass beads of the selective reflection means, a pearl paint containing fine acrylic pieces having an average particle diameter of 7 to 8 μm was applied by spraying.

  In Example 7, a multilayer dielectric optical thin film controlled to have a cutoff wavelength of 7 to 8 μm was deposited instead of the glass beads of the selective reflection means.

<Comparative Example 1>
In Example 1, the selective reflection means was not applied, and only a matte black paint was applied.

<Comparative example 2>
In Example 1, only the glass beads were directly applied as selective reflection means on the aluminum substrate without applying the matte black paint. The emissivity was 0.5 due to the influence of the acrylic paint which is a binder for glass beads.

<Comparative Example 3>
No coating or vapor deposition was performed, and both the front and back surfaces were left as an aluminum substrate. The emissivity was 0.1.

  The heat dissipation performance of the above test pieces was verified by the following method.

  As shown in FIG. 5, each test piece 10 has a high emissivity + selective reflection means 12 on the surface of an aluminum plate 11, and a K-type thermocouple 13 is attached to the center of the back surface with an aluminum tape 14. Further, a ceramic heater 16 was attached with a silicone sheet (hereinafter referred to as TIM) 15 having high thermal conductivity interposed therebetween. The ceramic heater 16 was regarded as a heat source inside the casing.

  Further, as shown in FIG. 6, a thermocouple 23 is similarly attached to the aluminum tape 24 on the back surface of the same aluminum plate 21 as the test piece 10 shown in FIG. The ceramic heater 26 was attached with the silicone sheet (TIM) 25 having high thermal conductivity interposed therebetween, and this was used as the external heat source 20.

  FIG. 7 shows the configuration of the measuring apparatus.

  All members other than the test piece 10 and the external heat source 20 are made of a cork sheet, which is a heat insulating material, and a heat transfer path other than heat radiation is excluded as much as possible. The test piece 10 was placed on the base cork sheet 31 and the ceramic heaters 16 and 26 were energized and heated. The input power was 2W. In this state, the temperature of the test piece 10 was measured when the amount of heat generated by the ceramic heater 16 was in a thermal equilibrium state with the heat radiation from the test piece 10. This is the result of “no external heat source”.

  Next, the external heat source 20 was placed on the support member 32 by laminating the cork sheets, with the matte black paint face down, and facing the test piece 10 at a distance of 2 cm. A cork sheet 33 is also laminated on the external heat source 20, and a heat transfer path other than heat radiation is eliminated as much as possible. A power of 4 W was applied to the ceramic heater 26 of the external heat source 20, and the temperature of the test piece 10 was measured when the thermal equilibrium state was similarly reached. This is the result of “with external heat source”. At this time, the temperature of the external heat source 20 was about 100 to 110 ° C.

  The above list of measurement conditions is summarized in Table 1, and the list of results is summarized in Table 2.

表１及び表２の結果に示されるように、実施例１〜９においては、程度の差はあるものの、外部熱源なしの状態で６３〜６４℃程度、外部熱源ありの状態で７０〜７１℃程度と、外部熱源によるテストピースの温度への影響は全て７℃程度となった。これに対して、比較例１では実施例１〜９よりも正味の放射率が高いため、外部熱源なしの状態では放射伝熱量が多く、実施例１〜９よりも低い温度を示したが、一方で外部熱源ありの状態では、反射する手段がないために外部熱源からの熱輻射による影響を大きく受けてしまい、２０℃以上も温度が上昇してしまった。

As shown in the results of Tables 1 and 2, in Examples 1 to 9, although there is a difference in degree, it is about 63 to 64 ° C. without an external heat source, and 70 to 71 ° C. with an external heat source. The influence of the external heat source on the temperature of the test piece was about 7 ° C. On the other hand, in Comparative Example 1, since the net emissivity is higher than in Examples 1 to 9, the amount of radiant heat transfer is large in the state without an external heat source, and the temperature is lower than in Examples 1 to 9. On the other hand, in the state with an external heat source, since there is no means to reflect, it was greatly affected by the heat radiation from the external heat source, and the temperature rose by 20 ° C. or more.

  Subsequently, in Comparative Example 2, since the reflection means was provided, the influence of the external heat source was almost the same as in Examples 1 to 9, but since there was no means for increasing the emissivity of the surface, the transfer from the internal heat source was performed. The heat could not be radiated efficiently, and the temperature rose about 10 ° C. compared to Examples 1-9.

  Finally, in Comparative Example 3, since the emissivity of the aluminum substrate is 0.1 (reflectance is 0.9), it was hardly affected by the external heat source, but the emissivity is lower than that of Comparative Example 2. The heat transfer from the internal heat source could not be efficiently radiated to the outside, resulting in the highest temperature of all the test pieces.

  From the above, sufficient heat dissipation performance can not be obtained regardless of which one of the means for increasing emissivity and the means for selective reflection is lacking, and Examples 1 to 9 having both are based on the heat dissipation performance for the internal heat source and the radiant heat from the external heat source. It was verified that it was effective in both ways of being affected.

  Here, the radiation spectrum of the test piece and the external heat source in this verification and the image of selective reflection by the retroreflective member / multilayer dielectric optical thin film are shown in FIG. In FIG. 8, the black body approximated spectrum is plotted assuming that the housing surface temperature is 70 ° C. and the external heat source temperature is 110 ° C. From FIG. 8, it can be confirmed that the threshold of selective reflection is located in the vicinity of the middle of the peak wavelength in both of the radiation spectra, and the radiation from the external heat source is positively reflected.

  In this verification, three kinds of matte black paint and black anodized treatment and glossy black paint are selected as means for increasing the emissivity, and glass beads, pearl paint and multilayer dielectric optical thin film are selected as means for selective reflection. Of course, the seeds are selected but not limited to these. As a means for increasing the emissivity, a white paint having an emissivity of 0.8 or more, and other surface treatments such as anodizing can be selected. A filter or the like can be selected. In addition, when resin is used for the housing material, since the material itself has a high emissivity of 0.8 to 0.9, it is more effective to further roughen the surface by machining or the like. .

  Next, the Example which used the illuminating device based on this invention as a vehicle headlamp is described. FIG. 9 is a schematic cross-sectional view of a vehicle headlamp. In this embodiment, a multilayer dielectric optical thin film 44 is bonded to the front surface of a housing 53.

  The front surface of the housing 43 is made of polycarbonate, and heat cannot be radiated from the front surface of the housing 43 from the viewpoint of appearance and design. However, the back surface of the housing 43 is irradiated with heat radiation exceeding 100 ° C., and the conventional structure cannot efficiently dissipate heat.

  Therefore, in this example, the lighting device according to the present invention was used as a vehicle headlamp. In this vehicle headlamp, the heat generated in the LED unit 41 is transferred to the polypropylene housing 43 through the aluminum heat conducting material 42, and passes through the multilayer dielectric optical thin film 44 to the outside air. Heat is dissipated. In addition, a metal filler is added to the material of the housing 43 to improve the thermal conductivity, and the surface of the housing 43 is roughened with an abrasive to improve the emissivity, so that the surface emissivity is 0.92. It is said.

  FIG. 10 shows a radiation spectrum from the casing and the external heating element, and FIG. 11 shows a reflection spectrum of the casing surface. The temperatures of the casing and the external heat source were 50 ° C. and 200 ° C., respectively.

  As apparent from FIGS. 10 and 11, the radiation spectrum from the housing is located on the longer wavelength side than the cutoff wavelength of the optical thin film, and the radiation spectrum from the external heating element is located on the short wavelength side. 9, the heat radiation 46 from the external heating element 45 is reflected, and only the heat radiation 47 from the housing 43 is selectively emitted to the outside. FIG. 12 shows the radiation spectra inside and outside the housing, respectively.

Further, when the approximate size of the case is 50 cm wide × 20 cm high × 20 cm deep, and the area of the heat radiating surface of the case is about 1000 cm ² , high emissivity + selective reflection structure With or without, a temperature reduction effect of about 20 ° C. can be expected.

  Next, the Example which used the illuminating device which concerns on this invention as an outdoor street lamp is described.

  FIG. 13 is a schematic cross-sectional view of an outdoor street lamp, and this embodiment shows an example in which the surface of the casing 53 is covered with a retroreflective material 54.

  In the illustrated outdoor street light, as in the tenth embodiment, the heat generated by the LED unit 51 is transferred to the aluminum casing 53 through the aluminum heat conducting material 52, passes through the retroreflective material 54, and passes through the external air. The heat is dissipated. The aluminum casing 53 is black anodized to improve the emissivity, and the emissivity of the surface is 0.95.

  Each radiation spectrum when the surface temperature of the sun is 6000 K and the temperature of the housing 53 is 50 ° C. is shown in FIG. The retroreflective material 54 was controlled to have a particle size of 3 μm and a refractive index of about 2 so as to reflect sunlight rays well.

  Since the peak of the radiation spectrum from the sun is located on the shorter wavelength side than the particle size of the retroreflective material, the heat from the sun is retroreflected, and the peak of the radiation spectrum from the housing is larger than the particle size of the retroreflective material. Since it is located on the long wavelength side, heat from the housing is transmitted without being reflected. Therefore, in the outdoor street lamp shown in FIG. 13, the heat radiation 56 from the sun 55 is retroreflected, and only the heat radiation 57 from the housing 53 is selectively emitted to the outside.

FIG. 15 shows the radiation spectra inside and outside the housing, respectively. Since the external heat source is as high as 6000 K, the separation of the radiation spectrum is large, and 95% or more of the radiant energy (1366 W / m ² ) from the sun can be reflected, which is very efficient.

In addition, when a plurality of housing units are arranged and the overall rough size is an outdoor street light having a width of 30 cm × length of 1 m × depth of 10 cm and an area of the heat radiation surface of 0.3 m ² , A temperature reduction effect of 50 ° C. or more can be expected with / without high emissivity + selective reflection structure.

It is a figure which shows the thermal radiation structure of the housing | casing surface in the conventional illuminating device. It is a figure which shows the thermal radiation structure at the time of using a multilayer dielectric optical thin film in the illuminating device which concerns on this invention. It is a figure which shows the thermal radiation structure at the time of using a retroreflection material in the illuminating device which concerns on this invention. It is a spectrum image figure of the selective reflection in the thermal radiation structure shown in FIG. It is a block diagram of the test piece used for Examples 1-9 and Comparative Examples 1-3. It is a block diagram of the external heat source used for verification of a test piece. It is a whole block diagram of the apparatus which verified the test piece. It is a spectrum image figure of selective reflection in Examples 1-9. It is a typical sectional view of a vehicular headlamp. It is a figure which shows the radiation spectrum of the housing | casing and external heat generation source in Example 10. FIG. It is a figure which shows the reflection spectrum of the housing | casing surface in Example 10. FIG. It is a figure which shows the radiation spectrum in the housing | casing in Example 10, and an outer side. It is a typical sectional view of an outdoor street lamp. It is a figure which shows the housing | casing and solar radiation spectrum in Example 11. FIG. It is a figure which shows the radiation spectrum in the housing | casing inner side in Example 11, and an outer side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 2 Multilayer dielectric optical thin film 3 Heat transfer from internal heat source 4 Thermal radiation from housing surface 5 External heat source 6 Thermal radiation from external heat source 7 Heat reflection by multilayer dielectric optical thin film 8 Retroreflective member 9 Recursion Reflection 10 Test piece 11 Aluminum plate 12 High emissivity + selective reflection means 13 Thermocouple 14 Aluminum tape 15 Silicone sheet (TIM)
16 Ceramic heater 20 External heat source 21 Aluminum plate 22 Matte black paint 23 Thermocouple 24 Aluminum tape 25 Silicone sheet (TIM)
26 Ceramic Heater 31 Base Cork Sheet 32 Support Member 33 Cork Sheet 41 LED Unit 42 Aluminum Thermal Conductive Material 43 Housing 44 Multilayer Dielectric Optical Thin Film 45 External Heating Element 46 Thermal Radiation from External Heating Element 47 Thermal Radiation from Housing 51 LED unit 52 Aluminum thermal conductive material 53 Housing 54 Retroreflective material 55 Sun 56 Thermal radiation from the sun 57 Thermal radiation from the housing

Claims (5)

In a lighting device including a light source that is a heat source and a housing that houses the light source,
The surface of the casing is provided with an emissivity improving means for increasing the emissivity in the infrared region, and the electromagnetic wave component on the shorter wavelength side than the wavelength at which the spectral spectrum is emitted from the casing is maximized. An illuminating device characterized in that by providing a material to be controlled over the entire surface, radiation from an external heat source is blocked and heat from an internal heat source is selectively radiated to the outside.   2. The illumination according to claim 1, wherein the emissivity of the housing surface is set to 0.8 or more by applying at least one of machining, chemical conversion, or coating to the housing surface as the emissivity improving means. apparatus.   By adhering the multilayer dielectric optical thin film to the surface of the housing, and adjusting the cutoff wavelength in the spectral transmittance of the multilayer dielectric optical thin film to the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the housing is maximum, The illumination device according to claim 1, wherein an electromagnetic wave component on a shorter wavelength side than a wavelength at which a radiation spectrum emitted from the housing is maximum is reflected.   Cover the housing surface with a retroreflective material, and reflect the electromagnetic wave component on the shorter wavelength side than the wavelength at which the radiation spectrum emitted from the housing has the maximum particle size and refractive index in the process of retroreflection. The lighting device according to claim 1, wherein the lighting device is controlled.   The lighting device according to claim 1, wherein the light source is configured by an LED.

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