JP6926200B2 - Headlight device - Google Patents

Description

The present invention relates to a light source device that obtains an emitted color by exciting a phosphor with a blue laser light source and a headlight device using the same.

With the remarkable development of solid-state light emitting elements such as LEDs in recent years, lighting devices using the solid-state light emitting elements as a light source have become compact and lightweight, and have a long life as a light source with low power consumption and excellent environmental protection. It has been widely used in various lighting fixtures, and has been used as a headlight device for vehicles that can be controlled in various ways as an in-vehicle electronic device and has excellent visibility, and also as a light source for a projection type display device. There is.

For example, conventionally, as a headlight device for a vehicle, a low beam LED light source array, a high beam LED light source array, and a first optical light guide that receives and collimates low beam light and high beam light from these LED light sources are collimated. Vehicle headlamps that include a second optical light guide that diffuses low-beam light and high-beam light as a combination of diffusion patterns and mechanically support these arrays and optical light guides in a casing are described in the following patent documents. Already known by 1.

Further, according to Patent Document 2 as a new light source device, a high-efficiency and compact solid-state light source device using a laser light source as a light source is disclosed. Specifically, a configuration is disclosed in which a green, red phosphor, or yellow phosphor is excited by a blue laser light to efficiently obtain white light in combination with the blue laser light which is the excitation light.

Special Table 2008-532250 Japanese Unexamined Patent Publication No. 2015-121606

An LED, which is a solid light source, has become effective to be used as a light emitting source in a headlamp device for a vehicle as its luminous efficiency is improved. However, the above-mentioned prior art and Patent Document 1 do not disclose specific technical means for improving the light utilization efficiency.

On the other hand, as shown in Patent Document 2 as a light source for a projector, a method has been proposed in which a phosphor is excited by a blue laser beam to reduce the phosphorescence and improve the light utilization efficiency of the lighting system. No specific technical means for improving the luminous efficiency of the phosphor is disclosed.

Therefore, the present invention has a vehicle having high utilization efficiency of an LED light source, particularly an excitation light from a blue LED and a light emitted from the excitation light, as a light source device that can be easily used as a modularized planar illumination light source. It is an object of the present invention to provide a light source for a headlight device for a blue laser projector or a blue laser projector.

As a first embodiment for achieving the above object, according to the present invention, a vehicle headlight device which is attached to a part of a vehicle and irradiates an illumination light on a road surface on which the vehicle travels. As a light source device that generates the illumination light, a blue LED is used as an excitation light source to excite a phosphor to obtain white light.

Further, as the light source for the projector as the second embodiment, the blue laser light is focused on the phosphor to excite the phosphor, the emission point is reduced, the ethandue is reduced, and the efficiency of the illumination optical system is improved. At this time, even if the excitation light is condensed and the amount of heat generated is large, the amount of heat radiation is large, and by reducing the divergence of light inside the phosphor, the reflection of the excitation light on the surface of the phosphor, and the reflection on the surface of the fluorescent light. A light source device having high luminous efficiency is provided.

According to the above-described invention, it is possible to realize a light source device that has high luminous efficiency of a light source that excites a phosphor by using blue light as excitation light, can be manufactured at low cost, is compact, and is easy to modularize, and has low power consumption. Therefore, it is possible to realize a headlight device for a vehicle and a light source device for a projector, which are excellent in environmental protection and have a long life.

It is an overall configuration (a) and the perspective view (b) of the light source part which applied the headlight device for a vehicle as Example 1 of the light source device of this invention as a headlight of an automobile. It is sectional drawing (b) which shows the whole structure (a) of the headlight device for a vehicle as Example 1 of the light source device of this invention, and the light source part thereof. It is a figure which shows the whole structure of the projector as Example 2 of the light source apparatus of this invention. This is the first embodiment of the light source portion of the illumination optical system of the projector. It is the second embodiment of the light source part of the illumination optical system of a projector. It is a figure which shows the modification which used the total reflection lens as a reflector in the 1st implementation of the light source part of the illumination optical system of a projector. It is a detailed cross-sectional view which shows the principle of the light source part by this invention which shows the example of the excitation light reflection type in which the excitation light is incident from the same direction as the emission direction of fluorescent light. It is a detailed cross-sectional view which shows the principle of the light source part by this invention which shows the example of the excitation light transmission type which incidents the excitation light from the direction different from the emission direction of fluorescent light. It is a detailed cross-sectional view which shows the light source part by this invention which shows the example of the excitation light reflection type in which the excitation light is incident from the same direction as the emission direction of fluorescent light. It is a detailed cross-sectional view which shows the light source part by this invention which shows the example of the excitation light transmission type which incidents the excitation light from the direction different from the emission direction of fluorescent light. It is a detailed cross-sectional view which shows the principle of the light source part by this invention which shows the example of the excitation light reflection type which incidents the excitation light by the prior art from the same direction as the emission direction of fluorescence light. It is a detailed cross-sectional view which shows the principle of the light source part by this invention which shows the example of the excitation light transmission type which incidents the excitation light by the prior art from the direction different from the emission direction of fluorescent light. It is a figure which shows the relationship between the incident angle and the reflection angle of the excitation light to a phosphor. It is a figure which shows an example of the angular characteristic of the reflectance with respect to the substance of the refractive index 1.5 with respect to P-polarized light and S-polarized light. It is a characteristic diagram which shows the excitation light incident angle characteristic of conversion efficiency with respect to blue excitation light of green fluorescence light. It is a characteristic figure which shows the incident angle dependence of the excitation light to the phosphor layer by polarized light. It is a characteristic diagram which shows the angle dependence of the excitation light with respect to the output of fluorescent light. It is a characteristic figure which shows the excitation light incident angle dependence to the phosphor which is an Example of this invention. It is a figure which shows the light conversion efficiency with respect to the incident angle for each excitation light polarization direction to a phosphor layer. It is a figure which shows the ratio of the light conversion efficiency by the polarization direction with respect to the angle of incidence of excitation light to a phosphor layer.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and various modifications and modifications by those skilled in the art can be made within the scope of the technical idea disclosed in the present specification. Further, in the drawings for explaining the present invention, those having the same function are shown with the same reference numerals, and the repeated description thereof may be omitted.

First, FIG. 1 shows a vehicle 1 equipped with a vehicle headlight device using a solid-state light emitting element, which is an embodiment of the present invention, with a perspective view thereof and a partially enlarged view thereof. FIG. 1A shows the entire vehicle 1 equipped with the headlight device 1000 for the vehicle of the present invention, and FIG. 1B shows an enlarged view of the headlight device portion of the vehicle. ..

FIG. 2A is a side cross section of the headlight device 1000 shown in FIG. 1B, and FIG. 2B shows a constituent cross section of the light source portion thereof. In addition, FIG. 3 employs the light source device according to the embodiment of the present invention as the light source, that is, uses the light source device of the headlight device to provide information including the traveling direction of the vehicle in front of the vehicle. It is a figure which shows the whole structure of the projector for a vehicle which projects and displays.

(Example 1)
As shown in these figures, the headlight device 1000 shown in FIG. 1 basically transmits the visible light lighting unit 10 which is a light source device and the illumination light emitted from the lighting unit to the space in front of the vehicle 1. It is an optical system for irradiating the road surface on which the vehicle 1 travels, and is composed of a so-called projector lens 51. Further, the projection optics may be configured by using the reflection mirror 60 instead of the projector lens 51, or as shown in FIG. 2A, it is composed of both the projector lens 51 and the reflection mirror 60. By doing so, the distribution of the irradiation light on the road surface may be controlled with high accuracy, and the volume of the entire headlight device may be reduced.

As is clear from these figures, in the headlight device 1000 of the present invention, the illumination light from the visible light illumination unit 10 is fluorescent light by irradiating the phosphor with the excitation light from the excitation light source 12. It is configured to obtain. In the light source device, for example, when white light is obtained, as shown in FIG. 2B, the phosphor 19 excited by the blue light beam 13 which is the excitation light from the excitation light source 12 is yellow or green and red. White light can be obtained by emitting a mixed color of the above and mixing it with the blue color of the excitation light. That is, it is preferable to emit a luminous flux in a wavelength region having a complementary color relationship with the excitation light with respect to white. The obtained irradiation light flux is bent in a predetermined direction by the reflection mirror 60 as shown in FIG. 2 (a). This enables more precise control of the irradiation direction and intensity depending on the degree of freedom in the shape of the reflecting surface.

Subsequently, the details of each configuration requirement of the headlight device 1000 according to the present invention described above will be described below.

<Light source unit>
In order to obtain white light, the visible light illumination unit 10 which is a light source device of the present invention has a semiconductor light source element LED (Light Emitting Diode) or LASER (Light Emitting Diode) which is one or a plurality of solid light sources described later as an excitation light source 12. Light Amplification by Stimulated Emission of Radiation) is used to excite the phosphor 19 that emits yellow or green and red, and the light obtained by exciting the excitation light is mixed with the excitation light to obtain a desired white light. As shown in FIG. 2B, a method of irradiating from the emission direction of mixed color light, reflecting fluorescent light and excitation light on the reflecting surface 17 and emitting them in a desired direction (hereinafter referred to as “reflection method”). , There is a method of arranging an excitation light source on the bottom surface of the groove in which the phosphor 19 is arranged (not shown, hereinafter referred to as "transmission method"), but a transmission method is adopted in order to make the entire headlight device compact. In many cases.

Hereinafter, the configuration and the effect obtained will be described with respect to the method when the blue laser light is used as the excitation light, focusing on the reflection method shown in FIG. 2B and for convenience of explanation.

The inventors have derived from experiments that it is effective to reduce the following three factors in order to efficiently obtain the light source light from the light source unit.
(1) The phosphor is efficiently irradiated with the excitation light 13 from the excitation light source 12.
(2) The fluorescence generated by the phosphor 19 is efficiently emitted in a desired direction.
(3) Increase the luminous efficiency of the phosphor.

In order to realize the above-mentioned (1), the phosphor layer containing the phosphor 19 is irradiated with the excitation luminous flux 13. At this time, an antireflection film 21 is provided on the surface in order to reduce reflection on the surface of the phosphor layer. Further, for the excitation light 13, the output of the fluorescence light was experimentally determined for the same input energy of the excitation light as in FIG. 13, which shows the relationship between the angle of incidence on the phosphor layer and the angle of reflection. As a result, as shown in FIG. 19, it was found that the use of P-polarized light has a higher light conversion efficiency (emission light energy / incident light energy) than S-polarized light and can extract light. FIG. 20 shows the ratio of the efficiency when P-polarized light is used and the light conversion efficiency when S-polarized light is used, with the incident angle of the excitation light as a parameter. It was found that P-polarized light has higher efficiency, and the most efficient is around an incident angle of 30 degrees. This was due to both the difference in reflectance at the interface due to the difference between the P wave and the S wave shown in FIG. 14 and the improvement in luminous efficiency by cooling the phosphor, which will be described in detail below.

Further, the inventors have changed the structure of the phosphor layer to the structure according to the prior art in which a gap exists between the phosphor 19 and the binder 23 shown in FIGS. 11 and 12, as shown in FIGS. 7 and 8. In order to significantly reduce the density of voids, the structure is such that the phosphor 19 and the binder 23 are fired to prevent reflection at the interface between the phosphor and the vacuum (or air). At this time, as the phosphor used, LuAG: Ce (refractive index 1.85) was used as the green phosphor, YAG: Ce (refractive index 1.82) was used as the yellow phosphor, and the binder was used. A comparative study was carried out using aluminum oxide (alumina) (refractive index 1.76) and titanium oxide (refractive index 2.5), which have high transparency and thermal conductivity. As a result, when aluminum oxide having a small difference in refractive index between the phosphor 19 and the binder 23 is used as the binder 23, the generation of scattered light 21 inside the phosphor is reduced. The result was that the light output was improved by 6% or more. That is, it was found that it is preferable to use a member having a refractive index difference of 0.2 or less from the phosphor as the binder.

Next, in order to realize (2) described above, a groove portion 16 is provided in the structures 15 and 18 provided with the phosphor layer as shown in FIGS. 9 and 10, and the opening shape of the groove portion 16 is shown in the drawing. In the cross-sectional direction of, a cross-sectional shape (so-called “mortar-shaped”) in which part or all of the portion becomes smaller in the depth direction is adopted. At this time, the light obtained in a desired direction can be emitted by providing the reflective films 17 and 20 having a visible light reflectance of 90% or more on the contact surface between the structure 18 and the phosphor 19. Further, when the phosphor 19 and the binder are fired on the structure 18, shrinkage occurs during cooling. As a result, an air or vacuum interface is generated between the reflecting surface and the phosphor layer, but since the average refractive index of the phosphor layer is about 1.75, some light is totally reflected and in a desired direction. Since it emits light, light can be efficiently extracted from the subsequent optical system.

Finally, regarding the technical means for realizing the above-mentioned (3), the inventors investigated the relationship between the phosphor temperature and the light conversion efficiency in the state of being irradiated with the excitation light, and photoconverted by increasing the temperature of the phosphor. We have found that the efficiency is reduced. Therefore, in order to reduce the phosphor temperature, the above-mentioned structure is made of a metal having a high thermal conductivity, and the reflective surface of the groove portion reflects the aluminum or silver alloy having a high reflectance even with a metallic reflective film. By providing the film, the light conversion efficiency was improved by 8% or more. At this time, by firing the phosphor 19 and the binder 23 made of aluminum oxide and thermally bonding them, the temperature rise of the phosphor due to the excitation light was reduced, and high efficiency was realized.

In addition, as another means of reducing the temperature rise, by irradiating the phosphor layer with excitation light at an angle, the energy density of the excitation light incident on the phosphor layer is reduced and the heat conduction efficiency after receiving heat is increased. We have found that the light output of excitation light and fluorescence light can be improved. The results are shown in FIG. The horizontal axis shows the angle of incidence of the excitation light on the phosphor layer, and the vertical axis shows the output of the excitation light and the fluorescent light. Further, the horizontal axis of FIG. 18 is the angle of incidence of the excitation light beam on the phosphor layer, and the vertical axis is the excitation light when the output when the excitation light is vertically incident on the phosphor layer is set to a relative value of 1.00. The output of the fluorescent light is compared and shown. As described above, the excitation light is obliquely irradiated to the phosphor layer to reduce the energy density of the excitation light incident on the phosphor layer, and as a result, heat is received. By increasing the heat conduction efficiency later, the light output of the excitation light and the fluorescence light was improved. From the above results, it is particularly preferable that the excitation ray is P-polarized light, and the incident angle thereof is configured to be incident in the range of 40 degrees to 70 degrees.

As described above, as the light source device of the present invention, the visible light illumination unit 10 is a semiconductor light source element LED (Light Emitting Diode) or LASER which is one or a plurality of solid light sources described later as an excitation light source 12 in order to obtain white light. (Light Amplification by Stimulated Emission of Radiation) was used to excite a phosphor 19 that emits yellow or green and red, and the light obtained by exciting the excitation light was mixed with the excitation light to obtain a desired white light. Further, as shown in FIG. 2B, in the embodiment, the light is irradiated from the emission direction of the mixed color, and the fluorescent light and the excitation light are reflected by the reflecting surfaces 17 and 20 and emitted in a desired direction. The method (hereinafter referred to as "reflection method") has been described. However, the present invention is not limited thereto, and as shown in FIGS. 8 and 10, in the transmission method in which the excitation light source is arranged on the bottom surface of the groove in which the phosphor 19 is arranged, the excitation light beam φ2 is on the incident side. Reflection loss is reduced by providing an antireflection film on the light emitting surface where a part of the fluorescent light and the excitation light are mixed and emitted. In these examples, there is no other difference in configuration, and it goes without saying that the same effect can be obtained with the same configuration.

(Example 2)
<Projector>
Hereinafter, a projector for a vehicle that employs a light source unit as another embodiment of the present invention as a light source will be described with reference to FIG. Note that this figure shows the overall configuration of the projector, and in particular, a method of performing light intensity modulation according to a video signal by a so-called transmissive liquid crystal panel will be described. In the figure, in order to distinguish the elements arranged in the optical path of each colored light, R, G, and B indicating the colored light are added after the reference numerals, and the subscripts of the colored light are omitted when it is not necessary to distinguish them. In addition, in order to clarify the polarization direction, the right-handed Cartesian coordinate system will be used in the figure below. That is, the optical axis 101 is the Z axis, the axis parallel to the paper surface of FIG. 3 in the plane orthogonal to the Z axis is the Y axis, the axis from the back surface to the front side of the figure is the X axis, and the plane parallel to the Y axis is the X axis. The Y direction and the direction parallel to the X axis are referred to as the X direction. Further, in order to distinguish the polarization direction, the polarized light having the polarization direction of X is referred to as X-polarized light and the polarized light having the polarization direction of Y is referred to as Y-polarized light.

In FIG. 3, the optical systems of the projector are an illumination optical system 100, an optical separation optical system 30, a relay optical system 40, three field lenses 29 (29R, 29G, 29B), and three transmissive liquid crystal panels 60 (60R, 60G, 60B), a photosynthetic prism 200 as a photosynthetic means, and a projection lens 300 as a projection means are provided. The liquid crystal panel 60 is provided with an incident side polarizing plate 50 (50R, 50G, 50B) on the light incident side and an emitting side polarizing plate 80 (80R, 80G, 80B) on the light emitting side. These optical elements are mounted on the substrate 550 to form the optical unit 500. Further, the optical unit 500 is mounted in a housing (not shown) together with a drive circuit 570 for driving the liquid crystal panel 60, a cooling fan 580 for cooling the liquid crystal panel 60, and a power supply circuit 560 for supplying electric power to each circuit. Constitute.

Hereinafter, details of each part constituting the above-mentioned projector will be described. The illumination optical system 100 that uniformly illuminates the liquid crystal panel 60, which is an image display element, includes the visible light illumination unit 10 including the solid-state light emitting element that emits substantially white light described above, and the first and second lenses constituting the optical integrator. It includes arrays 21 and 22, a polarization conversion element 25, and a condenser lens (superimposed lens) 27.

The photodecomposition optical system 30 that photo-resolves the substantially white light from the illumination optical system 100 into three primary color lights includes two dichroic mirrors 31 and 32 and a reflection mirror 33 that changes the direction of the optical path. Further, the relay optical system 40 includes a first relay lens 41 which is a field lens, a second relay lens 42 which is a relay lens, and optical path folding mirrors 45 and 46.

In such a configuration, a light source unit 10 composed of a solid-state light emitting element emits a light flux substantially parallel to the optical axis 101 shown by a broken line in FIG. Then, the light emitted from the light source unit 10 is incident on the polarization conversion integrator. This polarization conversion integrator includes an optical integrator that realizes uniform illumination consisting of a first array lens 21 and a second array lens 22, and polarization for aligning the polarization directions of light with a predetermined polarization direction and converting the light into linearly polarized light. It includes a polarization conversion element 25 composed of a beam splitter array. That is, in the above-mentioned polarization conversion integrator, the light from the second array lens 22 is aligned with a predetermined polarization direction, for example, X-polarized light of linearly polarized light by the polarization conversion element 25.

Then, the projected image of each lens cell of the first array lens 21 is superposed on each liquid crystal panel 60 by the condenser lens 27, the field lenses 29G and 29B, the relay optical system 40, and the field lens 29R, respectively. In this way, the liquid crystal panel is uniformly illuminated while aligning the light from the solid-state light source with a random polarization direction in a predetermined polarization direction (here, X-polarized light).

On the other hand, the optical separation optical system 30 separates substantially white light emitted from the illumination optical system 100 into B light (blue band light), G light (green band light), and R light (red band light). Then, light is guided to each optical path (B optical path, G optical path, R optical path) toward the corresponding liquid crystal panel 60 (60R, 60G, 60B). That is, the B light reflected by the dichroic mirror 31 is reflected by the reflection mirror 33, passes through the field lens 29B and the incident side polarizing plate 50B, and is incident on the liquid crystal panel 60B for B light (B optical path). Further, the G light and the R light pass through the dichroic mirror 31 and are separated into the G light and the R light by the dichroic mirror 32. The G light reflects off the dichroic mirror 32 and enters the G light liquid crystal panel 60G through the field lens 29G and the incident side polarizing plate 50G (G optical path). The R light passes through the icromirror 32 and enters the relay optical system 40. The R light incident on the relay optical system 40 is focused (converged) in the vicinity of the second relay lens 42 via the reflection mirror 45 by the first relay lens 41 of the field lens and diverged toward the field lens 29R. .. Then, the field lens 29R is made substantially parallel to the optical axis, passes through the incident side polarizing plate 50R, and is incident on the liquid crystal panel 60R for R light (R optical path).

Each liquid crystal panel 60 (60R, 60G, 60B) constituting the light intensity modulator is driven by a drive circuit 570, and the degree of polarization is enhanced by an incident side polarizing plate 50 (50R, 50G, 50B) having a transmission axis in the X direction. , The X-polarized color light incident from the optical separation optical system 30 is modulated according to the color image to form a Y-polarized optical image.

The Y-polarized optical image of each color light formed as described above is incident on the exit polarizing plate 80 (80R, 80G, 80B). The incident-side polarized plates 80R, 80G, and 80B are polarized plates having a transmission axis in the Y direction, whereby unnecessary polarization components (here, X-polarized light) are removed and the contrast is improved. The optical image of each color light formed by the above method is incident on a synthetic prism 200, which is a photosynthetic means, and is synthesized to obtain a color image, which is magnified and projected by a projection lens 300, for example, on a traveling road surface.

<Light source unit for projector>
FIG. 4 is a diagram for explaining the principle of the light source unit 10 of the projector for a vehicle as another configuration of the solid-state light source device which is one of the embodiments of the present invention. The unit 10 includes a semiconductor laser element group 110 in which a plurality of semiconductor laser elements or light emitting diodes that emit light in the blue band (B color), which is a light emitting source of a solid element, are arranged on a substantially disk-shaped substrate, and the semiconductor laser. A reflector 130 having, for example, a parabolic surface, which is arranged at an angle of about 45 degrees facing the laser light emitting surface of the element group 110, and rotates in the vicinity of the focal point (F) of the reflecting mirror. It includes a disk (wheel) member 140, and a driving means for rotationally driving the member at a desired rotational speed, for example, an electric motor 150.

A light source unit as a second embodiment of the present invention will be described with reference to FIG. The first reflector (reflector) 130 is configured to have a smaller diameter than the second reflector (reflector) 130', and white light can be obtained from the first reflector (reflector) 130. Excitation light from the semiconductor laser element group 110 is incident on the outer peripheral portion of the disk (wheel) member 140. A spherical reflector 149 is provided to reflect the light emitted from the vicinity of the focal point F so that the fluorescent light does not reach the reflecting surface 131 of the reflecting mirror (reflector) 130. According to such a spherical reflector 149, almost all of the fluorescent light emitted from the vicinity of the focal point F can be output via the reflector 130, so that the light utilization efficiency can be improved. Further, the emission direction of the emitted light from the phosphor 19 can be controlled by providing a fine recess having a mortar-shaped cross section shown in FIGS. 9 and 10 on the emitting side surface (upper surface) of the base material 142'. , The energy conversion efficiency is improved by increasing the light capture rate of the illumination optical system (not shown) in the subsequent stage.

In the above description, the fluorescence surface formed on the substrate and the reflection / diffusion surface or transmission / diffusion surface are sequentially switched over time with respect to the excitation light focused from the reflector in the vicinity of the focal point F. By dividing the surface of the base material on the disk into a plurality of segments and rotating them, the heat dissipation effect can be improved and the damage to the phosphor can be reduced. However, the present invention is not limited to this, and for example, a surface phosphor surface of a rectangular rectangular base material and a reflection / diffusion surface or a transmission / diffusion surface are formed and vibrated in a specific period or an unspecified period. Alternatively, by adopting a structure capable of changing the relative position with respect to the focal point F, it is possible to reduce the damage given to the phosphor by condensing the excitation light at one point of the phosphor.

FIG. 6 shows a configuration using a so-called total reflection lens 135, in which a total reflection surface and a condenser lens are formed of one member as a reflector. According to this configuration, the excitation light (blue laser beam) near the optical axis passes through the condenser lens 136, while the excitation light (blue laser beam) at a position away from the optical axis is completely reflected by the total reflection unit 137. It is reflected, and any light beam is focused on one point on the disk (wheel) member 140, and then reflected and diffused as blue light or converted to yellow light and diffused. Then, among the blue light and yellow light diffused from one point of the disk (wheel) member 140, the light rays near the optical axis pass through the condenser lens 136 again, and all the light rays become light rays parallel to the optical axis. Further, it is reflected by the separation mirror 120 and incident on the illumination optical type 100 of the projector. A reflective film may be formed on the surface of the total reflection portion 137, and the surface shape of the total reflection portion 137 is the same as that of the reflector, which has a curved surface such as a paraboloid or an ellipsoid. (Surface) is desirable. That is, even with such a configuration, white illumination light can be obtained and the influence of focal movement (axial chromatic aberration) due to color can be suppressed to a level where there is no practical problem.

The color separation mirror 120 shown in FIG. 6 is provided with a polarization separation film that transmits P-polarized light and reflects S-polarized light on the excitation (blue laser) light source side of the base material 121, and reflects on the opposite side. A dichroic coat that transmits blue light and reflects yellow light is deposited on the mirror (reflector) side. The blue laser light aligned with P-polarized light enters the separation mirror, passes through the polarization-separated coated surface dichroic coated surface, and is incident on the reflecting mirror (reflector). The excitation light (blue laser light) incident on the reflector is focused on one point on the disk (wheel) member, and some blue light excites the phosphor to emit yellow light, and some blue light. Light is polarized 90 degrees and becomes S-polarized light, which is diffused. After that, the light becomes parallel by the reflector and the blue light aligned with the yellow light and the S-polarized light is incident on the separation mirror 120 again.

On the other hand, the blue light aligned with the S polarization passes through the dichroic coated surface, is reflected by the polarization separation coated surface, and is incident on the illumination system of the projector.

The light source unit described above is not limited to the light source unit for the projector of the vehicle described above, and can also be adopted as the visible light illumination unit 10 which is the light source device of the headlight device 1000 described above. .. According to this, similarly to the above-mentioned light source unit, light obtained by exciting a phosphor 19 that emits yellow or green and red using a semiconductor light source element LED or LASER is mixed with the excitation light. It is possible to realize a solid-state light source device capable of obtaining desired white light and having excellent light emission intensity and heat dissipation effect. Further, the light source unit is not limited to a projector for vehicles, and can be used as a light source for a general projector that projects and displays various images on a surface such as a screen. It will be obvious to those skilled in the art.

The light source and the light source device according to various examples of the present invention have been described above. However, the present invention is not limited to the above-described examples, but is a specific technical means for improving the luminous efficiency of the phosphor and the utilization efficiency in the illumination optical system. Therefore, there is an example. It is also possible to add the configurations of other embodiments to the configurations of. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

1 ... Vehicle, 1000 ... Headlight device, 10 ... Visible light illumination unit, 12 ... Excitation light source, 13 ... Excitation light (blue light beam), 17 ... Reflective surface, 15, 18 ... Structure, 17, 20 ... Reflective film, 19 ... Phosphor, 23 ... Binder, 21, 22 ... Lens array, 25 ... Polarizing converter, 27 ... Condensing lens, 29 ... Field lens, 30 ... Optical separation optical system, 31, 32 ... Dicroic mirror, 33 ... Reflection Mirror, 40 ... Relay lens optical system, 50 ... Incident side polarizing plate, 60 ... Liquid crystal panel, 80 ... Exit side polarizing plate, 100 ... Illumination optical system, 200 ... Photosynthetic prism, 300 ... Projection lens, 500 ... Optical unit, 550 ... Base, 560 ... Power supply circuit, 570 ... Drive circuit, 580 ... Cooling fan outside LED collimator unit, 51 ... Projector lens, 60 ... Reflection mirror

Claims (2)

A vehicle headlight device that is attached to a part of a vehicle and irradiates the road surface on which the vehicle travels with illumination light.
Equipped with a light source device
The light source device that generates the illumination light includes a phosphor layer coated with a phosphor and an excitation light source that excites the phosphor.
The structure coated with the phosphor that constitutes the light source device that generates the illumination light has a groove portion for providing the phosphor layer, and the opening shape of the groove portion faces in the depth direction in the cross-sectional direction. The cross-sectional shape is such that part or all of it becomes smaller.
The excitation light from the excitation light source is configured to irradiate the phosphor layer with light having a specific polarization at an incident angle in the range of 40 degrees to 70 degrees with respect to the phosphor layer .
The phosphor layer is formed by firing the phosphor and the binder in the groove portion, and P-polarized light is used as the excitation light.
A reflective film having a reflectance of 90% or more with respect to visible light is provided on the contact surface between the structure and the phosphor layer, and an antireflection film is formed at the air-side interface of the phosphor layer.
A headlight device provided with an air or vacuum interface between the structure, the phosphor layer obtained by firing the phosphor with a binder, and the reflective film. The headlight device according to claim 1, wherein YAG: Ce (refractive index 1.82) is used as the phosphor, and a member having a refractive index difference of 0.2 or less from the phosphor is used as a binder.

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