JP2012124054A - Light-emitting device, vehicular headlight, and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device capable of easily obtaining light with sufficient intensity in order to activate a photocatalyst.SOLUTION: The light-emitting device includes an LED 1a for generating exciting light EL, a light-emitting body 4 for generating fluorescence by irradiating the exciting light EL generated from the LED 1a, a light guide member 2a for guiding the exciting light EL generated from the LED 1a to the light-emitting body 4, and a parabolic mirror 5 having a light reflecting concave surface SUF3 for reflecting the fluorescence generated from the light-emitting body 4. A photocatalyst coated film 6c is formed on at least a part of the light reflecting concave surface SUF3, and the excited light EL generated from the LED 1a activates a photocatalyst action of the photocatalyst contained in the photocatalyst coated film 6c.

Description

  The present invention relates to a light-emitting device that uses fluorescence generated by irradiating a phosphor (light-emitting body) with excitation light as illumination light, a vehicle headlamp including the light-emitting device, and a lighting device.

  In recent years, research on light-emitting devices using semiconductor light-emitting elements such as light-emitting diodes (LEDs) and semiconductor lasers (LDs) as excitation light sources has become active.

  As an example of a technique related to such a light emitting device, there is a light source device disclosed in Patent Document 1. This light source device includes an LD, a collimator (lens) that uses the laser beam from the LD as a parallel beam bundle, a condenser (lens) that collects the laser beam of the parallel beam bundle from the collimator, and the condenser. And a phosphor that absorbs the emitted laser light and emits incoherent light.

  By the way, when the light source device having the above configuration is used as it is in the atmosphere, dirt such as exhaust gas adheres to the reflecting mirror and the like, the reflectivity is lowered, and the illumination light extraction efficiency of the light source device as a whole is reduced over time. However, there is a problem that it decreases.

  Even if a projection lens is installed in the direction of propagation of the reflected light by the reflecting mirror and the inside of the light source device is sealed, it is difficult to achieve a completely sealed state. Adhering to the reflecting mirror and the projection lens is inevitable. Moreover, when the inside of a light source device is sealed, the inside of a light source device will become substantially impossible.

  As an example of a technique for solving the above problems, there is an illumination lamp disclosed in Patent Document 2. In this illumination lamp, a metal halide lamp (discharge lamp) is used as a light source, and a photocatalytic film is formed on at least one of the inner surface of the lens and the reflecting surface of the reflecting mirror. As a result, contamination due to exhaust gas or the like is prevented from accumulating and accumulating on the inner surface of the lens that cannot be cleaned and the reflecting surface of the reflecting mirror.

JP 2003-295319 A (published on October 15, 2003) Japanese Patent Laid-Open No. 11-273426 (published on Oct. 08, 1999)

  However, the illumination lamp disclosed in Patent Document 2 uses ultraviolet light as a by-product obtained by the discharge of the metal halide lamp for activating the photocatalytic action of the photocatalyst, so that it is sufficient for activating the photocatalyst. There is a possibility that ultraviolet light with a high intensity cannot be obtained.

  For example, since a metal halide lamp used for illumination usually has light in the visible region as a main component, the proportion of light in the ultraviolet region that is a by-product is small. For this reason, there is a possibility that ultraviolet light having sufficient intensity for activation of the photocatalyst cannot be obtained.

  In addition, even if the light intensity of the entire metal halide lamp is increased, the intensity of ultraviolet light as a by-product does not increase so much, so there is still a possibility that ultraviolet light having sufficient intensity for activation of the photocatalyst cannot be obtained. is there.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a light-emitting device and the like that can easily obtain light having sufficient intensity for activation of a photocatalyst.

  In order to solve the above problems, a light-emitting device of the present invention is generated from a light source that generates excitation light, a light-emitting body that generates fluorescence when irradiated with excitation light generated from the light source, and the light-emitting body. A reflecting mirror having a light reflecting concave surface that reflects fluorescence, and a photocatalytic film is formed on at least a part of the light reflecting concave surface, and the excitation light generated from the light source is a photocatalytic action of the photocatalyst contained in the photocatalytic film Is activated.

  According to the above configuration, the excitation light (as a main component of light) generated from the light source activates the photocatalytic action of the photocatalyst contained in the photocatalytic film as it is. Therefore, the excitation light (which is the main component of the light generated from the light source) is not a by-product light such as the ultraviolet light described in Patent Document 2 above, so that it is easy to provide sufficient light intensity for the activation of the photocatalyst. Can get to.

  Even if the intensity of the excitation light is weak and sufficient light intensity cannot be obtained for the activation of the photocatalyst, it is sufficient to increase the intensity of the excitation light by simply increasing the intensity of the excitation light. Can be easily obtained.

  In addition, according to the above configuration, the photocatalytic action of the photocatalyst is activated, and at least a part of the light reflecting concave surface of the reflecting mirror is decomposed and removed, so that the illumination light extraction efficiency of the entire apparatus decreases with time. Can also be suppressed.

  As mentioned above, according to the said structure, light of sufficient intensity | strength for activation of a photocatalyst can be obtained easily.

  “Excitation light activates the photocatalytic action of the photocatalyst” means, for example, that the wavelength of the excitation light is set to a wavelength that activates the photocatalytic action of the photocatalyst contained in the photocatalytic film, and the wavelength is , Meaning that the light emitter has a wavelength capable of generating fluorescence.

  Further, for example, when the wavelength that maximizes the photocatalytic activation effect is selected as the wavelength of the excitation light, the intensity of the excitation light required for the light source to activate the photocatalyst is suppressed. This also provides the secondary effect of reducing the power consumption of the light emitting device while maximizing the effect of activating the photocatalyst.

  Further, in the configuration using the metal halide lamp of Patent Document 2, since the power source is not stable, it is necessary to provide a ballast on the power source side. However, in the light emitting device of the present invention, it is not necessary to provide such a ballast. Therefore, a secondary effect that the configuration of the entire apparatus is simplified and the size of the entire apparatus can be reduced can be obtained.

  In addition to the above configuration, the light emitting device of the present invention further includes a light guide member for guiding excitation light generated from the light source to the light emitter, and a photocatalytic film is provided on at least a part of the surface of the light guide member. It may be formed.

  According to the above configuration, the photocatalytic action of the photocatalyst is activated, and at least a part of the dirt on the surface of the light guide member is decomposed and removed, so that the deterioration of the illumination light extraction efficiency over time in the entire apparatus is suppressed. can do.

  In the light emitting device of the present invention, in addition to the above configuration, the light guide member may be made of a material having a refractive index higher than 1.

  According to the said structure, the light guide member is comprised from the material which has a refractive index higher than air (refractive index = 1). Therefore, the excitation light can be guided by the principle that the light is confined in the region having a high refractive index without forming a reflection surface or the like that reflects the excitation light on the outer surface of the light guide member. Is easy to manufacture.

  In the light-emitting device of the present invention, in addition to the above configuration, the light guide member may be an excitation lens that adjusts the area of the spot of excitation light irradiated on the light emitter.

  According to the above configuration, since the area (irradiation area) of the excitation light spot irradiated on the light emitter can be adjusted, the light emission efficiency of the light emitter can be adjusted. Further, since the photocatalytic action of the photocatalyst is activated and at least a part of the dirt on the surface of the excitation lens is decomposed and removed, it is possible to suppress a decrease in the illumination light extraction efficiency over time in the entire apparatus. .

  For example, if the area of the spot of the excitation light is made smaller than the area of the surface (light irradiation surface) on the side where the excitation light of the light emitter is irradiated, the side surface sharing the side with the light irradiation surface of the light emitter The emitted fluorescence (side emission fluorescence) is reduced. Therefore, the ratio of the fluorescence emitted from the light emitting surface of the light emitter to the fluorescence emitted from the entire surface of the light emitter can be increased.

  In addition to the above-described configuration, the light-emitting device of the present invention includes a projection lens that is provided at the opening of the reflecting mirror and projects fluorescence generated from the light-emitting body to the outside of the reflecting mirror. A photocatalyst film may be formed on at least a part of the surface.

  According to the above configuration, the photocatalytic action of the photocatalyst is activated, and at least part of the dirt on the surface of the projection lens is decomposed / removed, so that the deterioration of the illumination light extraction efficiency with time in the entire apparatus is suppressed. be able to.

  In addition to the above structure, the light-emitting device of the present invention may have a photocatalytic film formed on at least a part of the surface of the light-emitting body.

  According to the above configuration, the photocatalytic action of the photocatalyst is activated, and at least a part of the dirt on the surface of the light emitter is decomposed and removed, so that it is possible to suppress a decrease in light emission efficiency over time of the light emitter.

  In addition to the above structure, the light-emitting device of the present invention preferably has a wavelength of excitation light generated from the light source of 340 nm to 450 nm.

  When the wavelength of the excitation light exceeds 450 nm, it becomes difficult to efficiently activate the photocatalytic action of the photocatalyst. Moreover, if it is 450 nm or less, by selecting the photocatalyst material, the absorption rate of the photocatalyst becomes 50% or more, and the photocatalytic action is efficiently activated (see FIG. 2). On the other hand, when the wavelength of the excitation light is less than 340 nm, for example, it becomes difficult to generate the excitation light using a semiconductor light emitting element.

  In the light-emitting device of the present invention, in addition to the above configuration, the light source is preferably a laser diode.

  According to the laser diode, the light density of the excitation light is increased, the luminous efficiency of the luminous body is increased, and the action of activating the photocatalyst is further enhanced.

  Further, in the light emitting device of the present invention, in addition to the above configuration, the light emitter is inserted into an insertion hole formed in the reflecting mirror, and a part of the excitation light irradiated to the light emitter is the above. You may make it permeate | transmit the inside of a light-emitting body.

  According to the said structure, excitation light permeate | transmits the inside of a light-emitting body, the transmitted light enters into a photocatalyst film | membrane, and a photocatalyst is activated. Further, the transmitted light is scattered by the phosphor particles contained in the luminescent material, and the transmitted light (transmitted excitation light) is diffused in the reflecting mirror, so that the photocatalyst is activated more efficiently.

  In addition to the above configuration, the light emitting device of the present invention may have a gap between a light emitter inserted into the insertion hole and the inner surface of the insertion hole.

  According to the above configuration, the excitation light (passing light) that has passed through the gap enters the photocatalyst film and the photocatalyst is activated. Further, by adjusting the size of the gap, it is possible to adjust the intensity of the passing light that has passed through the gap.

  In addition to the above configuration, the light emitting device of the present invention includes a transparent substrate that supports the light emitter from one side of an insertion hole formed in the reflecting mirror, and is provided on at least a part of the surface of the transparent substrate. A photocatalytic film may be formed.

  According to the above configuration, the photocatalytic action of the photocatalytic film is activated, and at least a part of the dirt on the surface of the transparent substrate is decomposed and removed, so that the deterioration of the illumination light extraction efficiency over time in the entire apparatus is suppressed. can do.

  In addition to the above structure, the light emitting device of the present invention has a phosphor concentration in the light emitter of 1 vol% or more and 30 vol% or less, and a thickness along the irradiation direction of the excitation light of the light emitter. However, it is preferable that they are 0.03 mm or more and 3 mm or less.

  When the concentration of the phosphor exceeds 30 vol%, the intensity of the transmitted light that passes through the light emitter becomes too weak. On the other hand, when the concentration of the phosphor is less than 1 vol%, the intensity of the scattered light scattered by the phosphor particles becomes too weak. Further, the intensity of the fluorescence generated from the light emitter becomes too weak.

  If the thickness of the illuminant along the irradiation direction of the excitation light exceeds 3 mm, the intensity of transmitted light that passes through the illuminant becomes too weak. On the other hand, if the thickness of the light emitter along the irradiation direction of the excitation light is less than 0.03 mm, the intensity of the fluorescence generated from the light emitter becomes too weak.

  In addition to the above-described structure, the light-emitting device of the present invention includes a reflecting plate that reflects a part of the excitation light that passes through the inside of the light-emitting body, and the light-emitting body may be supported by the reflecting plate. good.

  According to the said structure, a part of excitation light permeate | transmits a light-emitting body, and the transmitted light is return | folded (reflected) by a reflecting plate. Further, a part of the folded light passes through the light emitter and enters the photocatalyst film to activate the photocatalyst.

  In addition to the above structure, the light emitting device of the present invention has a phosphor concentration in the light emitter of 1 vol% or more and 30 vol% or less, and a thickness along the irradiation direction of the excitation light of the light emitter. However, it is preferable that they are 0.015 mm or more and 1.5 mm or less.

  When the concentration of the phosphor exceeds 30 vol%, the intensity of the transmitted light that passes through the light emitter becomes too weak. On the other hand, if the concentration of the phosphor is less than 1 vol%, the intensity of the fluorescence generated from the light emitter becomes too weak.

  When the thickness of the illuminant along the irradiation direction of the excitation light exceeds 1.5 mm, the path length of the transmitted light that passes through the illuminant becomes too long. On the other hand, if the thickness of the illuminant along the direction of excitation light irradiation is less than 0.015 mm, the intensity of the fluorescence generated from the illuminant becomes too weak.

  In addition to the above structure, the light emitting device of the present invention preferably has a reflectance of 0.03 to 0.5 on the surface of the light emitter with respect to the excitation light.

  If the reflectance of the surface of the light emitter is less than 0.03, the intensity of the reflected light becomes too weak. On the other hand, if the reflectance of the surface of the light emitter exceeds 0.5, the intensity of transmitted light that passes through the inside of the light emitter is too weak.

  Further, in the light emitting device of the present invention, in addition to the above configuration, the excitation light may be P-polarized light with respect to the light irradiation surface irradiated with the excitation light of the light emitter. The incident angle of the excitation light with respect to the light irradiation surface of the body is preferably not a Brewster angle.

  According to the above configuration, the photocatalytic action of the photocatalytic film can be enhanced only by adjusting the incident angle of the excitation light (installation position of the light source).

  “P-polarized light” means that the polarization direction of the excitation light is parallel to the plane including the incident light and the reflected light of the excitation light incident on the light irradiation surface of the light emitter, and the polarization direction is This refers to a case perpendicular to the incident direction of the excitation light (see FIG. 7B).

  Further, when the incident angle of the excitation light (P-polarized light) with respect to the light irradiation surface of the illuminant is a Brewster angle, the excitation light is not reflected at all on the light irradiation surface, so that the activation of the photocatalytic action of the photocatalyst is efficient. It is difficult to do it automatically.

  In the light emitting device of the present invention, in addition to the above configuration, the excitation light may be S-polarized light with respect to the light irradiation surface irradiated with the excitation light of the light emitter.

  According to the above configuration, the photocatalytic action of the photocatalytic film can be enhanced only by adjusting the incident angle of the excitation light (installation position of the light source). Further, there is no limit on the incident angle like the Brewster angle of P-polarized light.

  “S-polarized light” refers to the case where the polarization direction of the excitation light is perpendicular to the plane including the incident light beam and the reflected light beam incident on the light irradiation surface of the light emitter (FIG. 7 ( b)).

In the light-emitting device of the present invention, in addition to the above configuration, the photocatalytic film may include at least one compound selected from titanium oxide, titanium oxide doped with boron, and titanium oxide doped with nickel. preferable. As long as the photocatalytic action can be enhanced, another material may be doped into TiO ₂ , or nitrogen, a foreign metal, or the like may be ion-implanted into TiO ₂ .

  Further, the vehicle headlamp and the lighting device including the light emitting device are also included in the technical scope of the present invention.

  As described above, the light-emitting device of the present invention includes a light source that generates excitation light, a light-emitting body that generates fluorescence when irradiated with excitation light generated from the light source, and excitation light generated from the light source. A light guide member for guiding to the light emitter, and a reflecting mirror having a light reflecting concave surface for reflecting the fluorescence generated from the light emitter, wherein a photocatalytic film is formed on at least a part of the light reflecting concave surface, and the light source The excitation light generated from the light activates the photocatalytic action of the photocatalyst contained in the photocatalyst film.

  Therefore, there is an effect that light having sufficient intensity for activation of the photocatalyst can be easily obtained.

It is sectional drawing which shows the structure of the light guide type headlamp which is one Embodiment of this invention. It is a graph which shows the relationship between the wavelength of excitation light, and the absorption factor of the excitation light of a photocatalyst. It is sectional drawing which shows the structure of the transmission type headlamp which is other embodiment of this invention. It is sectional drawing which shows the structure of the transmission type headlamp which is further another embodiment of this invention. It is sectional drawing which shows the structure of the reflection type headlamp which is further another embodiment of this invention. It is sectional drawing which shows the structure of the reflection type headlamp which is further another embodiment of this invention. (A) is a graph which shows the relationship between the incident angle of excitation light, and the reflectance of the excitation light in the light irradiation surface of a light-emitting body, (b) demonstrates P polarized light and S polarized light regarding the said excitation light. It is explanatory drawing for doing. It is a conceptual diagram which shows the arrangement | positioning direction of the reflection type headlamp in a motor vehicle.

  An embodiment of the present invention will be described as follows with reference to FIGS. Descriptions of configurations other than those described in the following specific items may be omitted as necessary. However, in the case where they are described in other items, the configurations are the same. For convenience of explanation, members having the same functions as those shown in each item are given the same reference numerals, and the explanation thereof is omitted as appropriate.

[1. Configuration of light guide headlamp 10]
First, based on FIG. 1, the structure of the light guide type headlamp (light-emitting device, vehicle headlamp, illuminating device) 10 which is one Embodiment of this invention is demonstrated. FIG. 1 is a cross-sectional view schematically showing the configuration of the light guide type headlamp 10. As shown in FIG. 1, the light guide headlamp 10 includes an LED (light source) 1 a, a light guide member 2 a, a light emitter 4, a parabolic mirror (reflecting mirror) 5, and a projection lens 8.

(LED1a)
The LED 1a is a light emitting diode (LED) that functions as an excitation light source that generates excitation light EL. A plurality of the LEDs 1a may be provided. In this case, excitation light EL is generated from each of the plurality of LEDs 1a. Although only one LED 1a may be used, it is easier to use a plurality of LEDs 1a in order to obtain high-output excitation light EL.

  The LED 1a may have one light emitting point in one chip, or may have a plurality of light emitting points in one chip. In the present embodiment, the wavelength of the excitation light EL is 380 nm, but is not limited thereto, and may be 340 nm or more and 450 nm or less.

  When the wavelength of the excitation light EL exceeds 450 nm, it becomes difficult to efficiently activate the photocatalytic action of the photocatalyst contained in the photocatalyst coat films (photocatalyst films) 6a to 6e described later (see FIG. 2).

  If the wavelength of the excitation light EL is 450 nm or less, the photocatalyst absorption rate is 50% or more by selecting a photocatalyst material, and the photocatalytic action is efficiently activated (see FIG. 2). . On the other hand, when the wavelength of the excitation light EL is less than 340 nm, for example, it becomes difficult to generate the excitation light EL using a semiconductor light emitting element.

  As will be described later, a laser diode (LD) can be used as an excitation light source instead of a light emitting diode.

(Light guide member 2a)
The light guide member 2 a is a translucent member for guiding the excitation light EL generated from the LED 1 a to the light emitter 4. In addition, the shape of the light guide member 2a is a truncated cone shape in the present embodiment, but the shape of the light guide member 2a is not limited to this, and various shapes such as an elliptical truncated cone shape and a truncated pyramid shape are adopted. Can do. An optical fiber may be used as the light guide member 2a. In this case, an aspherical lens or the like is provided in front of the light emitting point of the LD 1b so that the excitation light EL from the LD 1b is incident on the incident end of the optical fiber, and the excitation light EL emitted from the output end of the optical fiber is emitted from the light emitter. 4 may be irradiated.

The material of the light guide member 2a may be any material as long as its refractive index n is higher than 1 (= refractive index of air) and transmits the excitation light EL. In this embodiment, it is made of quartz (SiO ₂ ). The refractive index n is 1.45. If the refractive index n of the material of the light guide member 2a is higher than 1, the excitation light EL can be guided by the principle that light is confined in a region where the refractive index n is high. It becomes easy.

(Luminescent body 4)
The light emitter 4 generates fluorescence by irradiating the excitation light EL generated from the LED 1a, and includes a phosphor that emits light upon receiving the excitation light EL. Specifically, the light emitter 4 is a phosphor in which a phosphor is dispersed inside a sealing material, or a phosphor is solidified. The light emitter 4 can be said to be a wavelength conversion element because it converts the excitation light EL into fluorescence.

  In the present embodiment, the light emitter 4 is disposed at the focal position of the parabolic mirror 5.

  In the present embodiment, the shape of the illuminant 4 is a cylindrical shape (disc shape) having a diameter of a circle on the bottom surface of 2 mm. However, the size and shape are not limited to this, and any size and various shapes can be used. You can choose. Examples of shapes other than the disc shape include a prismatic shape and an elliptical column shape.

  Next, as a phosphor included in the light emitter 4, for example, an oxynitride phosphor (for example, sialon phosphor) or a III-V compound semiconductor nanoparticle phosphor (for example, indium phosphorus: InP) is used. Can do. These phosphors have high heat resistance against the excitation light EL with high output (and / or light density) emitted from the LED 1 a, and are optimal for the light guide type headlamp 10. However, the phosphor of the light-emitting body 4 is not limited to the above-described phosphor, and may be other phosphors such as a nitride phosphor.

  The law stipulates that the illumination light of the light guide headlamp 10 must be white having a predetermined range of chromaticity. Therefore, the light emitter 4 includes a phosphor that is selected so that the illumination light is white.

  For example, when blue, green and red phosphors are included in the light emitter 4 and irradiated with excitation light EL of 405 nm, white light is generated.

  Alternatively, yellow light (or green and red phosphors) is included in the light-emitting body 4, and white light can be emitted even by irradiating so-called blue excitation light EL having a peak wavelength in a wavelength range of 440 nm to 450 nm. can get.

  The sealing material of the light emitter 4 is, for example, a glass material (inorganic glass, organic / inorganic hybrid glass) or a resin material such as silicone resin. Low melting glass may be used as the glass material. The sealing material is preferably highly transparent, and when the laser beam has a high output, a material having high heat resistance is preferable.

  In addition, it is preferable that the incident rate of excitation light EL with respect to the light irradiation surface with which the excitation light EL of the light-emitting body 4 is irradiated is 0.5 or more. When the incident rate of the excitation light EL with respect to the light irradiation surface of the light emitter 4 is less than 0.5, the light amount of the excitation light EL incident on the light emitter 4 becomes too small.

(Parabolic mirror 5)
The parabolic mirror 5 reflects the fluorescence generated by the light emitter 4 and forms a light bundle (illumination light) that travels within a predetermined solid angle. The parabolic mirror 5 may be, for example, a member having a metal thin film formed on the surface thereof or a metal member.

  In addition, the parabolic mirror 5 uses a rotating paraboloid (parabola) formed by rotating the parabola with the axis of symmetry of the parabola as a rotation axis as a reflecting surface (light reflecting concave surface SUF3SUF3). Thereby, the fluorescence of the light emitter 4 can be efficiently projected within a narrow solid angle, and as a result, the utilization efficiency of the fluorescence can be increased.

  A part that is not a parabola may be included in a part of the parabola mirror 5. Moreover, the reflecting mirror included in the light emitting device of the present invention may include a parabolic mirror having a closed circular opening or a part thereof. The reflecting mirror is not limited to a parabolic mirror, and may be a semi-elliptical mirror or a hemispherical mirror. That is, the reflecting mirror only needs to include at least a part of a curved surface formed by rotating a figure (ellipse, circle, parabola) about the rotation axis on the reflecting surface.

  An insertion hole 7a is provided at the bottom of the light reflecting concave surface SUF3 (rotary paraboloid) of the parabolic mirror 5, and the tip of the light guide member 2a having a short cross section is inserted into the insertion hole 7a. Has been.

(Projection lens 8)
Next, the projection lens 8 is provided in the opening (right side with respect to the paper surface) of the light reflecting concave surface SUF3 of the parabolic mirror 5, and seals the light guide headlamp 10. The fluorescence generated from the light emitter 4 or the fluorescence reflected by the parabolic mirror 5 is projected to the outside of the parabolic mirror 5 through the projection lens 8. Further, the material of the projection lens 8 can be exemplified by quartz, but is not limited thereto.

  In the present embodiment, the projection lens 8 has a convex lens shape and a lens function. However, the projection lens 8 may have a concave lens shape as well as a convex lens shape. Further, the projection lens 8 does not necessarily have a structure having a lens function. The projection lens 8 has at least a light transmitting property that transmits the fluorescence generated from the light emitter 4 or the fluorescence reflected by the light reflecting concave surface SUF3. good. That is, the projection lens 8 may be made of any material as long as it has at least translucency.

  The thickness of the projection lens 8 is preferably about 3.0 mm or less. If the thickness exceeds 3.0 mm, the absorption of fluorescence cannot be ignored and the member cost increases.

  When an LD (light source, laser diode) 1b, which will be described later, is used as an excitation light source, the surface SUF4 and the surface SUF5 of the projection lens 8 are generated from the light emitter 4 while blocking the excitation light EL (laser light) from the LD 1b. It is preferable to cover with a filter (film) that transmits the fluorescent light or the fluorescent light reflected by the light reflecting concave surface SUF3.

  Most of the coherent laser light transmitted through the light emitter 4 is converted into incoherent fluorescence. 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 filter.

(Photocatalyst coating films 6a to 6e)
Next, the photocatalyst coat films (photocatalyst films) 6a to 6e will be described with reference to FIGS. In the light guide type headlamp 10 of this embodiment, as shown in FIG. 1, the surface SUF1 of the light guide member 2a, the surface SUF2 of the light emitter 4, the light reflecting concave surface SUF3 of the parabolic mirror 5, and the inner surface (surface of the projection lens 8) Photocatalyst coat films 6a to 6e are formed on each of SUF4) and the outer surface (surface SUF5).

In addition, although the photocatalyst coat films 6a to 6e of the present embodiment include TiO ₂ (titanium oxide) as a photocatalyst, the photocatalyst is not limited to this, for example, TiO ₂ doped with B (boron) described later or TiO ₂ doped with B and Ni (nickel), or a combination of the above photocatalysts. Further, as long as the photocatalytic action can be enhanced, other materials may be doped into TiO ₂ , and nitrogen, foreign metal, or the like may be ion-implanted into TiO ₂ .

  Thereby, the photocatalyst contained in the photocatalyst coat film 6a on the surface SUF1 is activated while the excitation light EL propagates through the light guide member 2a. Thereby, since the dirt adhering to the light guide member 2a is decomposed and removed, it is possible to suppress a decrease in the fluorescence extraction efficiency of the light guide type headlamp 10 over time.

  Further, when the excitation light EL is incident on the light emitter 4, the photocatalyst contained in the photocatalyst coat film 6b on the surface SUF2 of the light emitter 4 is activated and the dirt is decomposed and removed, so that the light emission efficiency of the light emitter 4 is improved. A decrease over time can be suppressed.

  Further, the excitation light EL incident on the light emitter 4 is incident on the parabolic mirror 5 and the projection lens 8 as reflected light (excitation light) RL and transmitted light (excitation light) PL, and the light reflecting concave surface SUF3 of the parabolic mirror 5 is used. The photocatalyst contained in the photocatalyst coat film 6c, the photocatalyst coat film 6d on the surface SUF5 of the projection lens 8 and the photocatalyst coat film 6e on the surface UF6 is activated and the dirt is decomposed and removed. A temporal decrease in the fluorescence extraction efficiency of the headlamp 10 is suppressed.

Next, based on FIG. 2, the relationship between the wavelength (nm: nanometer) of the excitation light EL and the absorption rate (%) of the excitation light of the photocatalyst (TiO ₂ ) contained in the above-described photocatalyst coating films 6a to 6e. explain.

The solid line shown in FIG. 2 shows the relationship between the wavelength of the excitation light EL of the photocatalyst (TiO ₂ ) contained in the photocatalyst coat films 6a to 6e and the absorption rate of the excitation light EL of the photocatalyst (TiO ₂ ).

As described above, in this embodiment, the wavelength of the excitation light EL of the LED 1a is 380 nm. Therefore, the wavelengths of the reflected light RL and the transmitted light PL are also 380 nm, and it can be seen from the graph of FIG. 2 that the absorption rate of the excitation light EL of TiO ₂ is about 50%. ₂ that the absorption rate of the excitation light EL of TiO ₂ is 50% or more when the wavelength of the excitation light EL is 380 nm or less.

  Note that “excitation light EL activates the photocatalytic action of the photocatalyst” is, for example, that the wavelength of the excitation light EL is set to a wavelength that activates the photocatalytic action of the photocatalyst contained in the photocatalyst coat films 6a to 6e. And the wavelength means that the light-emitting body 4 is a wavelength which can generate | occur | produce fluorescence.

(Method for forming photocatalyst coating films 6a to 6e)
Next, a method for forming the photocatalyst coat films 6a to 6e will be described. As examples of this forming method, the following two methods can be exemplified.
(1) Method 1: A photocatalyst coat film is formed by immersing a member in a sol-gel solution containing a photocatalyst (TiO ₂ or the like) and drying the removed member.
(2) Method 2: A mixture of a photocatalyst and an organic binder or inorganic binder is sprayed and sprayed onto the member by spraying. The photocatalyst coat film is formed by drying the sprayed member.

[2. Configuration of transmissive headlamp 20]
Next, based on FIG. 3, the structure of the transmissive | pervious headlamp (light-emitting device, vehicle headlamp, illuminating device) 20 which is other embodiment of this invention is demonstrated. FIG. 3 is a cross-sectional view schematically showing the configuration of the transmissive headlamp 20.

As shown in FIG. 3, the transmissive headlamp 20 is different from the above-described light guide headlamp 10 in the following points and the other configurations are the same, and thus description thereof will be omitted as appropriate.
(1) The LD 1b is used instead of the LED 1a as an excitation light source.
(2) The point which uses the lens for excitation (light guide member) 2b instead of the light guide member 2a.
(3) The light emitter 4 is inserted through an insertion hole 7 a provided at the bottom of the parabolic mirror 5 while being supported by the transparent substrate 3.

(LD1b)
The LD 1b is a laser diode (LD) that functions as an excitation light source that generates excitation light EL. According to the laser diode, the light density of the excitation light EL is increased, the luminous efficiency of the light emitter 4 is increased, and the action of activating the photocatalyst is further enhanced. A plurality of LDs 1b may be provided. In this case, excitation light EL is generated from each of the plurality of LDs 1b. Although only one LD 1b may be used, it is easier to use a plurality of LDs 1b in order to obtain high-output excitation light EL.

  The LD 1b may have one light emitting point per chip, or may have a plurality of light emitting points per chip. The wavelength of the excitation light EL is 405 nm in the present embodiment, but is not limited thereto, and may be 340 nm or more and 450 nm or less. The reason is as described above.

(Excitation lens 2b)
The excitation lens 2b is for adjusting the area (irradiation area) of the spot of excitation light irradiated on the light emitter 4. According to the excitation lens 2b, the area of the spot of the excitation light EL irradiated on the light emitter 4 can be adjusted, so that the light emission efficiency of the light emitter 4 can be adjusted. In addition, since the photocatalytic action of the photocatalyst is activated and the dirt on the surface SUF1 of the excitation lens 2b is decomposed and removed, it is possible to suppress a decrease in the illumination light extraction efficiency with time in the entire transmission headlamp 20. You can also. The material of the excitation lens 2b can be exemplified by quartz, but is not limited thereto.

  The shape of the excitation lens 2b is a biconvex lens in the present embodiment, but is not limited thereto. For example, a biconcave lens, a planoconvex lens, a planoconcave lens, a convex meniscus lens, a concave meniscus lens, and the like can be exemplified.

  Another example of the lens is a GRIN lens (Gradient Index lens).

  The GRIN lens is a lens that produces a lens action due to a refractive index gradient inside the lens even if the lens is not convex or concave.

  Therefore, when the GRIN lens is used, the lens action can be generated while the end surface of the GRIN lens is kept flat.

(Transparent substrate 3)
As shown in FIG. 3, the transparent substrate 3 supports the light emitter 4 from one side of the insertion hole 7 a formed in the parabolic mirror 5. Moreover, although the material of the transparent substrate 3 can illustrate quartz and sapphire, for example, it is not limited to this.

  The light emitter 4 is inserted into the insertion hole 7a formed in the parabolic mirror 5, and there is a gap between the light emitter 4 inserted into the insertion hole 7a and the inner surface of the insertion hole 7a. ing. That is, the size of the light emitter 4 is designed to be smaller than the size of the hole of the insertion hole 7a. Thereby, the passing light (excitation light) PL ′ that has passed through the gap enters the photocatalyst coat films 6 b to 6 e and the photocatalyst is activated. Further, by adjusting the size of the gap, it is possible to adjust the intensity of the passing light PL ′ that has passed through the gap. Therefore, the balance between the luminous efficiency of the luminous body 4 and the degree of activation of the photocatalytic action of the photocatalyst can be adjusted.

  Further, part of the excitation light EL irradiated to the light emitter 4 is transmitted through the light emitter 4. As a result, the excitation light EL passes through the inside of the light emitter 4, and the transmitted light (not shown) enters the photocatalyst coat films 6b to 6e to activate the photocatalyst. Further, the transmitted light is scattered by the phosphor particles contained in the light emitter 4, and the transmitted light is diffused in the parabolic mirror 5, so that the photocatalyst is activated more efficiently.

(Photocatalyst coating films 6a to 6f)
Next, the photocatalyst coat films (photocatalyst films) 6a to 6f will be described with reference to FIG. In the transmissive headlamp 20 of this embodiment, as shown in FIG. 3, the surface SUF1 of the excitation lens 2b, the surface SUF2 of the light emitter 4, the light reflecting concave surface SUF3 of the parabolic mirror 5, and the inner surface of the projection lens 8 (surface SUF4). ), The outer surface (surface SUF5), and the surface SUF6 of the transparent substrate 3 are formed with photocatalyst coat films 6a to 6f, respectively.

In addition, although the photocatalyst coat films 6a to 6f of the present embodiment include TiO ₂ doped with B as a photocatalyst, the photocatalyst is not limited thereto, and for example, TiO ₂ doped with B and Ni described later. It may be. Further, as long as the photocatalytic action can be enhanced, other materials may be doped into TiO ₂ , and nitrogen, foreign metal, or the like may be ion-implanted into TiO ₂ .

  As a result, the photocatalyst contained in the photocatalyst coat film 6a on the surface SUF1 is activated while the excitation light EL propagates through the excitation lens 2b. As a result, the dirt adhering to the excitation lens 2b is decomposed and removed, so that it is possible to suppress a decrease in the fluorescence extraction efficiency of the transmission headlamp 20 over time.

  Further, when the excitation light EL is incident on the transparent substrate 3, the photocatalyst included in the photocatalyst coating film 6f on the surface SUF6 is activated and the dirt is decomposed and removed, so that the fluorescence extraction efficiency of the transmissive headlamp 20 is increased. Can be suppressed over time.

  Further, when the excitation light EL is incident on the light emitter 4, the photocatalyst contained in the photocatalyst coat film 6b on the surface SUF2 of the light emitter 4 is activated and the dirt is decomposed and removed, so that the light emission efficiency of the light emitter 4 is improved. A decrease over time can be suppressed.

  Further, the passing light PL ′ passing through the gap between the light emitter 4 and the inner surface of the insertion hole 7a and the transmitted light (not shown) transmitted through the light emitter 4 are incident on the parabolic mirror 5 and the projection lens 8 and parabolic. The photocatalyst contained in the photocatalyst coat film 6c on the light reflecting concave surface SUF3 of the mirror 5, the photocatalyst coat film 6d on the surface SUF5 of the projection lens 8, and the photocatalyst coat film 6e on the surface UF6 is activated, and the dirt is decomposed and removed. Therefore, it is possible to suppress a decrease in the fluorescence extraction efficiency of the transmissive headlamp 20 over time.

Next, the relationship between the wavelength of the excitation light EL and the absorption rate of the excitation light of the photocatalyst (B-doped TiO ₂ ) contained in the above-described photocatalyst coating films 6a to 6f will be described with reference to FIG.

The short broken line shown in FIG. 2 indicates the wavelength of the excitation light EL of the photocatalyst (B-doped TiO ₂ ) contained in the photocatalyst coating films 6a to 6f and the excitation light EL of the photocatalyst (B-doped TiO ₂ ). The relationship with the absorption rate is shown.

In this embodiment, the wavelengths of the excitation light EL, the passage light PL ′, and the transmitted light (not shown) are 405 nm, and the absorption rate of the excitation light EL of TiO ₂ doped with B is well over 50%. . ₂ that the absorptance of the excitation light EL of TiO ₂ doped with B is 50% or more when the wavelength of the excitation light EL is 450 nm or less.

(Method of forming photocatalyst coat films 6a to 6f)
Next, a method for forming the photocatalyst coat films 6a to 6f will be described. As examples of this forming method, the following two methods can be exemplified.
(1) Method 1: A photocatalyst coat film is formed by immersing a member in a sol-gel solution containing a photocatalyst (such as TiO ₂ doped with B) and drying the extracted member.
(2) Method 2: A mixture of a photocatalyst and an organic binder or inorganic binder is sprayed and sprayed onto the member by spraying. The photocatalyst coat film is formed by drying the sprayed member.

In addition, the doping amount of B is 1 × 10 ¹⁵ cm ⁻³ to 1 × 10 ²² cm ⁻³ .

[3. Configuration of transmissive headlamp 30]
Next, based on FIG. 4, the structure of the transmission type headlamp (light-emitting device, vehicle headlamp, illumination device) 30 which is further another embodiment of this invention is demonstrated. FIG. 4 is a cross-sectional view schematically showing the configuration of the transmissive headlamp 30.

As shown in FIG. 4, the transmissive headlamp 30 is different from the transmissive headlamp 20 described above in the following points and the other configurations are the same, and thus the description thereof will be omitted as appropriate.
(1) The LD 1b having a wavelength of excitation light EL of 445 nm is used as the excitation light source.
(2) Although the light emitter 4 is supported by the transparent substrate 3 and is inserted through the insertion hole 7a provided at the bottom of the parabolic mirror 5, it is the same as the transmissive headlamp 20, but the light emitter 4 And there is almost no gap between the insertion hole 7a and the inner surface of the insertion hole 7a (the size of the insertion hole 7a and the size of the light emitter 4 are substantially the same).

(LD1b)
Since the configuration of the LD 1b other than the wavelength (445 nm) of the excitation light EL is the same as that of the transmissive headlamp 20, description thereof is omitted here.

(Transparent substrate 3)
As shown in FIG. 4, the transparent substrate 3 supports the light emitter 4 from one side of the insertion hole 7 a formed in the parabolic mirror 5.

  The light emitter 4 is inserted into an insertion hole 7 a formed in the parabolic mirror 5 so that a part of the excitation light EL irradiated to the light emitter 4 is transmitted through the light emitter 4. It has become. As a result, the excitation light EL passes through the inside of the light emitter 4, and the transmitted light (excitation light) PL enters the photocatalyst coat films 6b to 6e, thereby activating the photocatalyst. Further, since the transmitted light PL is scattered by the phosphor particles included in the light emitter 4, the transmitted light PL is diffused in the parabolic mirror 5, so that the photocatalyst is activated more efficiently.

(Range of concentration of phosphor and thickness of luminous body 4)
The concentration of the phosphor contained in the light emitter 4 is 10 vol% in the present embodiment, but is not limited to this, and is preferably 1 vol% or more and 30 vol% or less. When the concentration of the phosphor exceeds 30 vol%, the intensity of transmitted light that passes through the light emitter 4 becomes too weak. On the other hand, when the concentration of the phosphor is less than 1 vol%, the intensity of the scattered light scattered by the phosphor particles becomes too weak. Further, the intensity of the fluorescence generated from the light emitter 4 becomes too weak.

  In addition, the thickness t along the irradiation direction of the excitation light EL of the light emitter 4 is 2 mm in the present embodiment, but is not limited thereto, and is preferably 0.03 mm or more and 3 mm or less. When the thickness t of the light emitter 4 exceeds 3 mm, the intensity of the transmitted light that passes through the light emitter 4 becomes too weak. On the other hand, if the thickness t of the light emitter 4 is less than 0.03 mm, the intensity of the fluorescence generated from the light emitter 4 becomes too weak.

  As described above, the light intensity of the transmitted light PL can be adjusted by adjusting the phosphor concentration and the thickness t. Therefore, the balance between the luminous efficiency of the luminous body 4 and the degree of activation of the photocatalytic action of the photocatalyst can be adjusted.

(Photocatalyst coating films 6a to 6f)
Next, the photocatalyst coat films 6a to 6f will be described with reference to FIG. In the transmissive headlamp 30 of this embodiment, as shown in FIG. 4, the surface SUF1 of the excitation lens 2b, the surface SUF2 of the light emitter 4, the light reflecting concave surface SUF3 of the parabolic mirror 5, and the inner surface of the projection lens 8 (surface SUF4). ), The outer surface (surface SUF5), and the surface SUF6 of the transparent substrate 3 are formed with photocatalyst coat films 6a to 6f, respectively.

In addition, although the photocatalyst coat films 6a to 6f of the present embodiment include TiO ₂ doped with B and Ni as a photocatalyst, the photocatalyst is not limited thereto. For example, as long as the photocatalytic action can be enhanced, another material may be doped into TiO ₂ , or nitrogen, a foreign metal, or the like may be ion-implanted into TiO ₂ .

  As a result, the photocatalyst contained in the photocatalyst coat film 6a on the surface SUF1 is activated while the excitation light EL propagates through the excitation lens 2b. As a result, the dirt adhering to the excitation lens 2b is decomposed and removed, so that it is possible to suppress a decrease in the fluorescence extraction efficiency of the transmission headlamp 30 over time.

  Further, when the excitation light EL is incident on the transparent substrate 3, the photocatalyst contained in the photocatalyst coating film 6f on the surface SUF6 is activated and the dirt is decomposed and removed, so that the fluorescence extraction efficiency of the transmissive headlamp 30 is improved. Can be suppressed over time.

  Further, when the excitation light EL is incident on the light emitter 4, the photocatalyst contained in the photocatalyst coat film 6b on the surface SUF2 of the light emitter 4 is activated and the dirt is decomposed and removed, so that the light emission efficiency of the light emitter 4 is improved. A decrease over time can be suppressed.

  Further, the transmitted light PL transmitted through the light emitter 4 is incident on the parabolic mirror 5 and the projection lens 8, and the photocatalytic coating film 6 c on the light reflecting concave surface UF3 of the parabolic mirror 5 and the photocatalytic coating film 6 d on the surface UF5 of the projection lens 8. Since the photocatalyst contained in the photocatalyst coating film 6e on the surface SUF6 is activated and the dirt is decomposed / removed, it is possible to suppress a decrease in the fluorescence extraction efficiency of the transmission headlamp 30 over time. .

Next, based on FIG. 2, the relationship between the wavelength of the excitation light EL and the absorption rate of the excitation light of the photocatalyst (B and Ni-doped TiO ₂ ) included in the above-described photocatalyst coating films 6a to 6f will be described.

The long broken line shown in FIG. 2 shows the wavelength of the excitation light EL when the TiO ₂ doped with B and Ni is used as the photocatalyst, and the absorption rate of the excitation light EL of the photocatalyst (TiO ₂ doped with B and Ni). The relationship is shown.

As shown in FIG. 2, when the wavelength of the excitation light EL is 445 nm, the absorption rate of the excitation light EL of TiO ₂ doped with B and Ni is well above 50%.

(Method of forming photocatalyst coat films 6a to 6f)
Next, a method for forming the photocatalyst coat films 6a to 6f will be described. As examples of this forming method, the following two methods can be exemplified.
(1) Method 1: A photocatalyst coat film is formed by immersing a member in a sol-gel solution containing a photocatalyst (such as TiO ₂ doped with B and Ni) and drying the removed member.
(2) Method 2: A mixture of a photocatalyst and an organic binder or inorganic binder is sprayed and sprayed onto the member by spraying. The photocatalyst coat film is formed by drying the sprayed member.

Incidentally, each of the doping amount of B and Ni are ^{0.5 × 10 15 cm -3 ~0.5 ×} 10 22 cm -3.

[4. Configuration of Reflective Headlamp 40]
Next, the configuration of a reflective headlamp (light emitting device, vehicle headlamp, lighting device) 40 according to still another embodiment of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view schematically showing the configuration of the reflective headlamp 40.

As shown in FIG. 5, the reflective headlamp 40 is different from the above-described transmissive headlamp 30 in the following points and the other configurations are the same, and thus the description thereof will be omitted as appropriate.
(1) Instead of the parabolic mirror 5, a half parabolic mirror (reflecting mirror) 5h and a metal base (reflecting plate) 5p are used.
(2) The luminous body 4 is supported by the metal base 5p.
(3) A window portion 7b is provided at a position immediately above the light emitter 4 in the half parabolic mirror 5h, and the incident angle θ of the excitation light EL with respect to the light irradiation surface of the light emitter 4 is 0 °. The point being irradiated toward the luminous body 4 from.

(Excitation lens 2b)
In the excitation lens 2b, the area of the spot of the excitation light EL (wavelength 445 nm) is preferably made smaller than the area of the surface (light irradiation surface) on the side where the excitation light of the light emitter 4 is irradiated. Thereby, the fluorescence (side emission fluorescence) emitted from the side surface sharing the side with the light irradiation surface of the light emitter 4 is reduced. Therefore, the ratio of the fluorescence emitted from the light irradiation surface of the light emitter 4 to the fluorescence emitted from the entire surface of the light emitter 4 can be increased.

(Half parabolic mirror 5h)
The half parabolic mirror 5h reflects the fluorescence generated by the light emitter 4, and forms a light bundle (illumination light) that travels within a predetermined solid angle. The half parabolic mirror 5h may be, for example, a member having a metal thin film formed on the surface thereof or a metal member.

  The half parabolic mirror 5h includes a partial curved surface (half parabola) obtained by cutting the paraboloid of revolution along a plane including the rotation axis.

  A part of the half parabolic mirror 5h having such a shape is disposed above the upper surface (light irradiation surface) of the light emitter 4 having a larger area than the side surface. That is, the half parabolic mirror 5 h is arranged at a position covering the upper surface of the light emitter 4. If it demonstrates from another viewpoint, a part of side surface of the light-emitting body 4 has faced the direction of the opening part (right side with respect to paper surface) of the half parabolic mirror 5h.

  By making the positional relationship between the light emitter 4 and the half parabolic mirror 5h as described above, it is possible to efficiently project the fluorescence of the light emitter 4 within a predetermined solid angle. Can be increased.

  Moreover, according to said structure, the half parabolic mirror 5h has the half parabola (light reflection concave surface UF3) obtained by cut | disconnecting a parabola in the plane containing a rotating shaft, and is equivalent to the remaining half of a parabola. A structure other than the parabola can be placed in the part. If this structure is a metal base 5p with high thermal conductivity as described later and the light emitter 4 is brought into contact with the structure, the light emitter 4 can be efficiently cooled.

  In the above configuration, most of the fluorescence that could not be controlled by the half parabolic mirror 5h is emitted to the parabolic side. By utilizing this characteristic, a wide range on the parabolic side of the reflective headlamp 40 can be illuminated.

  The LD 1b is arranged outside the half parabolic mirror 5h, and the half parabolic mirror 5h is formed with a window portion 7b that transmits or passes the excitation light EL. In the present embodiment, the window portion 7b is an opening (hole), but is not limited thereto, and may include a transparent member that can transmit the excitation light EL. For example, a transparent plate provided with a filter that transmits the excitation light EL and reflects white light (fluorescence of the light emitter 4) may be provided as the window portion 7b. In this configuration, the fluorescence of the light emitter 4 can be prevented from leaking from the window portion 7b.

  A part that is not a parabola may be included in a part of the half parabola mirror 5h. Further, the reflecting mirror included in the light emitting device of the present invention may include a half parabolic mirror having a closed semicircular opening or a part thereof. The reflecting mirror is not limited to a half parabolic mirror, and may be a semi-elliptical mirror or a hemispherical mirror. That is, the reflecting mirror only needs to include at least a part of a curved surface formed by rotating a figure (ellipse, circle, parabola) about the rotation axis on the reflecting surface.

(Metal base 5p)
In the present embodiment, the light emitter 4 is supported by a metal base 5 p, and the metal base 5 p reflects a part of the excitation light EL that passes through the inside of the light emitter 4.

  Thereby, a part of the excitation light EL is transmitted through the light emitter 4, and the transmitted light is folded (reflected) by the metal base 5p. Further, a part of the folded light SL (wavelength 445 nm) passes through the light emitter 4 and enters the photocatalyst coating films 6b to 6e, and the photocatalyst is activated.

  The metal base 7 is made of metal (for example, copper or iron). Therefore, the metal base 7 has high thermal conductivity, and can efficiently dissipate heat generated by the light emitter 4. In addition, the metal base 5p is not limited to what consists of metals, The member containing materials (quartz, sapphire, etc.) with high heat conductivity other than a metal may be sufficient. However, the surface of the metal base 7 that comes into contact with the light emitter 4 preferably functions as a reflecting surface. When the surface is a reflecting surface, the excitation light EL incident from the upper surface of the light emitter 4 is converted into fluorescence, and then reflected by the reflecting surface and directed toward the half parabolic mirror 5h. Alternatively, the excitation light EL that has entered from the upper surface of the light emitter 4 can be reflected by the reflecting surface and again directed to the inside of the light emitter 4 to be converted into fluorescence.

  Since the metal base 7 is covered with the half parabolic mirror 5h, it can be said that the metal base 7 has a surface facing the light reflecting concave surface SUF3 of the half parabolic mirror 5h. It is preferable that the surface of the metal base 7 on the side where the light emitter 4 is provided is substantially parallel to the rotation axis of the paraboloid of the half parabolic mirror 5h and substantially includes the rotation axis.

(Range of concentration of phosphor and thickness of luminous body 4)
In the present embodiment, the concentration of the phosphor contained in the light emitter 4 is 8 vol%, but is not limited thereto, and is preferably 1 vol% or more and 15 vol% or less. When the concentration of the phosphor exceeds 15 vol%, the intensity of the transmitted light that passes through the light emitter 4 becomes too weak. On the other hand, if the concentration of the phosphor is less than 1 vol%, the intensity of the fluorescence generated from the light emitter 4 becomes too weak.

  In addition, the thickness t along the irradiation direction of the excitation light EL of the light emitter 4 is 1 mm in the present embodiment, but is preferably 0.015 mm or more and 1.5 mm or less. When the thickness t of the light emitter 4 exceeds 1.5 mm, the path length of the transmitted light that passes through the light emitter 4 becomes too long. On the other hand, when the thickness t of the light emitter 4 is less than 0.015 mm, the intensity of the fluorescence generated from the light emitter 4 becomes too weak.

(Photocatalyst coating films 6a to 6e)
Next, the photocatalyst coat films 6a to 6e will be described with reference to FIG. In the reflective headlamp 40 of the present embodiment, as shown in FIG. 5, the surface SUF1 of the excitation lens 2b, the surface SUF2 of the light emitter 4, the light reflecting concave surface SUF3 of the half parabolic mirror 5h, and the inner surface (surface of the projection lens 8) Photocatalyst coat films 6a to 6e are formed on each of the SUF4) and the outer surface (surface SUF5), and a photocatalyst coat film (photocatalyst film) 6c 'is also formed on the surface SUF3' of the metal base 5p. .

The photocatalyst coat films 6a to 6e and the photocatalyst coat film 6c ′ of the present embodiment each contain TiO ₂ doped with B and Ni as photocatalysts, but the photocatalyst is not limited thereto. For example, as long as the photocatalytic action can be enhanced, another material may be doped into TiO ₂ , or nitrogen, a foreign metal, or the like may be ion-implanted into TiO ₂ .

  As a result, the photocatalyst contained in the photocatalyst coat film 6a on the surface SUF1 is activated while the excitation light EL propagates through the excitation lens 2b. As a result, the dirt adhering to the excitation lens 2b is decomposed and removed, so that it is possible to suppress a decrease in the fluorescence extraction efficiency of the reflective headlamp 40 over time.

  Further, when the excitation light EL is incident on the light emitter 4, the photocatalyst contained in the photocatalyst coat film 6b on the surface SUF2 of the light emitter 4 is activated and the dirt is decomposed and removed, so that the light emission efficiency of the light emitter 4 is improved. A decrease over time can be suppressed.

  Further, the transmitted light (excitation light; not shown) transmitted through the light emitter 4 and the folded light SL from the metal base 5p are incident on the half parabolic mirror 5h, the metal base 5p, and the projection lens 8, and light from the half parabolic mirror 5h. Included in the photocatalyst coat film 6c on the reflective concave surface SUF3, the photocatalyst coat film 6d on the surface SUF5 of the projection lens 8, the photocatalyst coat film 6e on the surface SUF6, and the photocatalyst coat film 6c ′ on the surface SUF3 ′ of the metal base 5p Since the photocatalyst is activated and the dirt is decomposed and removed, it is possible to suppress a decrease in the fluorescence extraction efficiency of the reflective headlamp 40 over time.

[5. Configuration of Reflective Headlamp 50]
Next, the configuration of a reflective headlamp (light emitting device, vehicle headlamp, lighting device) 50 according to still another embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view schematically showing the configuration of the reflective headlamp 50.

As shown in FIG. 6, the reflective headlamp 50 is different in the following points from the reflective headlamp 40 described above, and the other configurations are the same, and thus the description thereof will be omitted as appropriate.
(1) Although the point which uses LD1b whose wavelength of excitation light EL is 445 nm is the same as an excitation light source, excitation light EL is a P polarized light with respect to the light irradiation surface of the light-emitting body 4. FIG.
(2) The incident angle θ of the excitation light EL to the light irradiation surface of the illuminator 4 is 30 °, and the position of the window portion 7c in the half parabolic mirror 5h is the excitation light to the illuminator 4 at this incident angle θ. A point that can be irradiated with EL.

(P-polarized light)
Here, “P-polarized light” means that the polarization direction pd of the excitation light EL is parallel to the plane including the incident light and the reflected light of the excitation light EL incident on the light irradiation surface of the illuminator 4, and In this case, the polarization direction pd is perpendicular to the incident direction of the excitation light EL (see FIGS. 6 and 7B).

  In addition, when the incident angle of the excitation light EL (P-polarized light) with respect to the light irradiation surface of the light emitter 4 is a Brewster angle, the excitation light EL is not reflected at all on the light irradiation surface, so that the photocatalytic activity of the photocatalyst is activated. It is difficult to perform the conversion efficiently. Therefore, the incident angle θ is preferably not a Brewster angle.

  By making the excitation light EL P-polarized light, the photocatalyst coating film can be obtained only by adjusting the incident angle θ of the excitation light EL (installation position of the LD 1b) without adjusting the concentration or thickness t of the phosphor of the light emitter 4. It becomes possible to enhance the photocatalytic action of 6a to 6e. Moreover, since the tolerance | permissible_range of the installation position of LD1b is wide, the freedom degree of design is high.

(Incident angle θ)
Next, the incident angle θ when the excitation light EL is P-polarized light will be described with reference to FIG.

  The broken line shown in FIG. 7A indicates the relationship between the incident angle θ (incident angle) when the excitation light EL is P-polarized light and the reflectance R with respect to the light irradiation surface of the light emitter 4. According to the figure, the incident angle θ is preferably from 0 ° to 85 ° (except for Brewster angle = 60 °). Note that, when the refractive index of the light emitter 4 changes, the characteristic of the reflectance R changes, but the wavelength of the incident excitation light EL does not affect this graph. Therefore, the relationship between the incident angle θ and the reflectance R does not depend on the constituent material and size of the light emitter 4.

(S-polarized light)
In this embodiment, the excitation light EL is P-polarized light, but the excitation light EL may be S-polarized light.

  Here, “S-polarized light” refers to the case where the polarization direction pd of the excitation light EL is perpendicular to the plane including the incident light and the reflected light of the excitation light EL incident on the light irradiation surface of the light emitter 4. (See FIG. 7B).

  If the excitation light EL is S-polarized light, the photocatalyst coat film 6a can be adjusted only by adjusting the incident angle θ of the excitation light EL (installation position of the LD 1b) without adjusting the concentration or thickness t of the phosphor of the light emitter 4. It becomes possible to enhance the photocatalytic action of ˜6e. Moreover, there is no restriction | limiting of incident angle (theta) like the Brewster angle of P polarized light. Moreover, since the tolerance | permissible_range of the installation position of LD1b is wide, the freedom degree of design is high.

(Incident angle θ)
Next, the incident angle θ when the excitation light EL is S-polarized light will be described with reference to FIG.

  The solid line shown in FIG. 7A indicates the relationship between the incident angle θ (incident angle) when the excitation light EL is S-polarized light and the reflectance R with respect to the light irradiation surface of the light emitter 4. According to the figure, the incident angle θ is preferably 0 ° to 72 °.

(Reflectance R)
Next, the reflectance R of the light irradiation surface of the light emitter 4 is preferably 0.03 or more and 0.5 or less. If the reflectance R is less than 0.03, the intensity of the surface reflected light (excitation light) rL (wavelength 445 nm) becomes too weak. On the other hand, when the reflectance R exceeds 0.5, the intensity of transmitted light that passes through the inside of the light emitter 4 is too weak.

(Range of concentration of phosphor and thickness of luminous body 4)
The concentration of the phosphor contained in the light emitter 4 is 30 vol% in the present embodiment, but is not limited to this. Moreover, although the thickness t along the irradiation direction of the excitation light EL of the light emitter 4 is 2 mm in the present embodiment, it is not limited to this.

(Photocatalyst coating films 6a to 6e)
Next, the photocatalyst coat films 6a to 6e will be described with reference to FIG. In the reflective headlamp 50 of the present embodiment, as shown in FIG. 6, the surface SUF1 of the excitation lens 2b, the surface SUF2 of the light emitter 4, the light reflecting concave surface SUF3 of the half parabolic mirror 5h, and the inner surface (surface of the projection lens 8) In addition to the photocatalyst coat films 6a to 6e formed on each of the SUF4) and the outer surface (surface SUF5), the photocatalyst coat film 6c ′ is also formed on the surface SUF3 ′ of the metal base 5p.

The photocatalyst coat films 6a to 6e and the photocatalyst coat film 6c ′ of the present embodiment each contain TiO ₂ doped with B and Ni as photocatalysts, but the photocatalyst is not limited thereto. For example, as long as the photocatalytic action can be enhanced, another material may be doped into TiO ₂ , or nitrogen, a foreign metal, or the like may be ion-implanted into TiO ₂ .

  As a result, the photocatalyst contained in the photocatalyst coat film 6a on the surface SUF1 is activated while the excitation light EL propagates through the excitation lens 2b. As a result, the dirt adhering to the excitation lens 2b is decomposed and removed, so that it is possible to suppress a decrease in the fluorescence extraction efficiency of the reflective headlamp 50 over time.

  Further, when the excitation light EL is incident on the light emitter 4, the photocatalyst contained in the photocatalyst coat film 6b on the surface SUF2 of the light emitter 4 is activated and the dirt is decomposed and removed, so that the light emission efficiency of the light emitter 4 is improved. A decrease over time can be suppressed.

  Further, transmitted light (excitation light; not shown) transmitted through the light emitter 4 and surface reflected light (excitation light) rL (wavelength 445 nm) on the light irradiation surface of the light emitter 4 are a half parabolic mirror 5h and a metal base 5p. , Incident on the projection lens 8, the photocatalytic coating film 6 c of the light reflecting concave surface SUF 3 of the half parabolic mirror 5 h, the photocatalytic coating film 6 d of the surface UF 5 of the projection lens 8, the photocatalytic coating film 6 e of the surface UF 6, and Since the photocatalyst contained in the photocatalyst coat film 6c ′ of the 5p surface SUF3 ′ is activated and the dirt is decomposed and removed, it is possible to suppress a decrease in the fluorescence extraction efficiency of the reflective headlamp 40 over time. it can.

(Reflection type headlamp installation method)
Next, FIG. 8 is a concept showing the arrangement direction of the reflective headlamp 40 or 50 when the reflective headlamp 50 (or the reflective headlamp 40) is applied to a headlight of an automobile (vehicle) 100. FIG. As shown in FIG. 8, the reflective headlamp 40 or 50 may be disposed on the head of the automobile 100 such that the half parabolic mirror 5h is positioned vertically downward. In this arrangement method, the front side of the automobile 100 is sufficiently brightly illuminated and the front lower side of the automobile 100 is also brightened due to the light projection characteristics of the half parabolic mirror 5h.

  The reflective headlamp 40 or 50 may be applied to a traveling headlamp (high beam) for an automobile, or may be applied to a passing headlamp (low beam).

[6. Overview of headlamp functions
As described above, in the light guide type headlamp 10, the transmission type headlamps 20 and 30, and the reflection type headlamps 40 and 50 (hereinafter referred to as each headlamp), they are generated from the LED 1a or the LD 1b. The excitation light EL (as a main component) directly activates the photocatalytic action of the photocatalyst contained in the photocatalyst coat films 6a to 6e, the photocatalyst coat film 6f, and / or the photocatalyst coat film 6c ′. Therefore, the excitation light EL (which is the main component of the light generated from the LED 1a or the LD 1b) is not a by-product light such as the ultraviolet light of the above-mentioned Patent Document 2, so that the light of sufficient light for the activation of the photocatalyst can be obtained. Strength can be easily obtained.

  In addition, since the intensity of the excitation light EL is weak, even when it is not possible to obtain a sufficient light intensity for the activation of the photocatalyst, it is possible to easily generate a sufficient intensity of light simply by increasing the power of the excitation light EL. Obtainable.

  Further, according to the above configuration, the photocatalytic action of the photocatalyst is activated and the dirt such as the light reflecting concave surface SUF3 of the parabolic mirror 5 or the half parabolic mirror 5h is decomposed and removed. It is also possible to suppress a decrease in extraction efficiency with time.

  From the above, it is possible to easily obtain light having sufficient intensity for activating the photocatalytic action of the photocatalyst.

  Further, for example, when the wavelength that maximizes the photocatalytic activation effect of the photocatalyst is selected as the wavelength of the excitation light EL, the power of the excitation light EL required for the LED 1a or LD1b to activate the photocatalyst is suppressed. Is done. This also provides a secondary effect that the power consumption of each headlamp can be reduced while maximizing the photocatalytic activation effect.

  Further, in the metal halide lamp of Patent Document 2, since the power supply is not stable, it is necessary to provide a ballast on the power supply side. However, in each of the headlamps, it is not necessary to provide such a ballast. The secondary effect of simplifying the configuration of the headlamp and reducing the overall size of each headlamp can also be obtained.

  The present invention can also be expressed as follows.

  That is, in the illumination device according to the present invention, in the illumination device using the light source and the phosphor, the photocatalyst coating film may be provided on at least one of the inner surface of the lens of the illumination device, the mirror surface, and the surface of the excitation light waveguide. .

  In the illumination device of the present invention, the light source wavelength may be 450 nm or less.

  Further, the lighting device of the present invention may use an LD as a light source.

  In the illumination device of the present invention, a light emitter made of a phosphor may be fitted in a hole of a mirror, and excitation light may pass through the light emitter.

  Moreover, the illuminating device of this invention may be installed in the board | substrate with which fluorescent substance is transparent in the wavelength range of excitation light, and the photocatalyst coating film may be provided in the transparent substrate.

  In the illumination device of the present invention, the light source wavelength may be smaller than the hole of the mirror.

  In the lighting device of the present invention, the phosphor concentration in the light emitter may be 30 vol% or less, and the thickness of the light emitter may be 3 mm or less.

  In the lighting device of the present invention, the light emitter may be attached to a metal or the like, and the excitation light may be reflected by the light emitter.

  In the illumination device of the present invention, the phosphor concentration in the light emitter may be 15 vol% or less, and the height of the light emitter may be 1.5 mm.

  In the lighting device of the present invention, a light source may be installed so that the reflectance of the surface reflection of the light emitter is 0.03 or more.

  In the illumination device of the present invention, the light source may be an LD, the excitation light may be P-polarized light, and the incident angle may not be a Brewster angle.

  In the illumination device of the present invention, the light source may be an LD, and the excitation light may be S-polarized light.

In addition, the lighting device of the present invention may use any one of TiO ₂ , B-doped TiO ₂ , Ni-doped TiO ₂ , or a combination thereof as a photocatalyst.

[Additional Notes]
The present invention is not limited to the above-described embodiments and examples, and various modifications can be made within the scope shown in the claims, and obtained by appropriately combining technical means disclosed in different examples. Such embodiments are also included in the technical scope of the present invention.

  The light emitting device of the present invention can be applied not only to a vehicle headlamp but also to other lighting devices. An example of the other lighting device is a downlight. A downlight is a lighting device installed on the ceiling of a structure such as a house or a vehicle. In addition, the illumination device of the present invention may be realized as a headlamp of a moving object other than a vehicle (for example, a human, a ship, an aircraft, a submersible, a rocket), a searchlight, a projector, a down You may implement | achieve as indoor lighting fixtures (stand lamp etc.) other than a light.

1a LED (light source)
1b LD (light source, laser diode)
2a Light guide member 2b Excitation lens 3 Transparent substrate 4 Light emitter 5 Parabolic mirror (reflecting mirror)
5h Half parabolic mirror (reflecting mirror)
5p metal base (reflector)
6a-6f Photocatalyst coat film (photocatalyst film)
6c 'photocatalyst coat film (photocatalyst film)
7a Insertion hole 8 Projection lens 10 Light guiding headlamp (light emitting device, vehicle headlamp, lighting device)
20, 30 Transmission type headlamp (light emitting device, vehicle headlamp, lighting device)
40, 50 Reflective headlamp (light emitting device, vehicle headlamp, lighting device)
EL excitation light n refractive index PL transmitted light (excitation light)
PL 'passing light (excitation light)
R reflectance RL reflected light (excitation light)
rL Surface reflected light (excitation light)
SL Folding light (excitation light)
SUF1 surface SUF2-6 surface SUF3 light reflecting concave surface SUF3 'surface t thickness

Claims (20)

A light source that generates excitation light;
A light emitting body that generates fluorescence when irradiated with excitation light generated from the light source;
A reflecting mirror having a light reflecting concave surface for reflecting the fluorescence generated from the light emitter, and
A photocatalytic film is formed on at least a part of the light reflecting concave surface;
Excitation light generated from the light source activates the photocatalytic action of the photocatalyst contained in the photocatalyst film. A light guide member for guiding the excitation light generated from the light source to the light emitter;
The light-emitting device according to claim 1, wherein a photocatalytic film is formed on at least a part of the surface of the light guide member.   The light-emitting device according to claim 2, wherein the light guide member is made of a material having a refractive index higher than one.   The light-emitting device according to claim 2, wherein the light guide member is an excitation lens that adjusts an area of a spot of excitation light applied to the light emitter. A projection lens that is provided at the opening of the reflecting mirror and projects the fluorescence generated from the light emitter to the outside of the reflecting mirror;
The light-emitting device according to claim 1, wherein a photocatalytic film is formed on at least a part of the surface of the projection lens.   6. The light-emitting device according to claim 1, wherein a photocatalytic film is formed on at least a part of the surface of the light-emitting body.   The light emitting device according to any one of claims 1 to 6, wherein a wavelength of excitation light generated from the light source is 340 nm or more and 450 nm or less.   The light emitting device according to any one of claims 1 to 7, wherein the light source is a laser diode. The luminous body is inserted into an insertion hole formed in the reflecting mirror,
The light emitting device according to any one of claims 1 to 8, wherein a part of the excitation light irradiated to the light emitter is transmitted through the inside of the light emitter.   The light emitting device according to claim 9, wherein a gap exists between the light emitter inserted into the insertion hole and the inner surface of the insertion hole. A transparent substrate that supports the light emitter from one side of an insertion hole formed in the reflecting mirror;
The light-emitting device according to claim 9 or 10, wherein a photocatalytic film is formed on at least a part of the surface of the transparent substrate.   The concentration of the phosphor contained in the light emitter is 1 vol% or more and 30 vol% or less, and the thickness along the irradiation direction of the excitation light of the light emitter is 0.03 mm or more and 3 mm or less. The light emitting device according to any one of claims 9 to 11. Comprising a reflector that reflects a portion of the excitation light that passes through the interior of the light emitter,
The light emitting device according to claim 1, wherein the light emitter is supported by the reflecting plate.   The concentration of the phosphor contained in the light emitter is 1 vol% or more and 30 vol% or less, and the thickness along the irradiation direction of the excitation light of the light emitter is 0.015 mm or more and 1.5 mm or less. The light emitting device according to claim 13.   The light emitting device according to claim 13 or 14, wherein a reflectance of the surface of the light emitter to the excitation light is 0.03 or more and 0.5 or less. The excitation light is P-polarized light with respect to the light irradiation surface irradiated with the excitation light of the illuminant,
The light emitting device according to any one of claims 13 to 15, wherein an incident angle of the excitation light with respect to the light irradiation surface of the light emitter is not a Brewster angle.   The light emitting device according to any one of claims 13 to 15, wherein the excitation light is S-polarized light with respect to a light irradiation surface irradiated with the excitation light of the light emitter.   18. The photocatalytic film includes at least one compound selected from titanium oxide, titanium oxide doped with boron, and titanium oxide doped with nickel. 18. The light-emitting device of description.   A vehicle headlamp comprising the light-emitting device according to any one of claims 1 to 18.   An illumination device comprising the light-emitting device according to claim 1.

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