WO2019230935A1 - Wavelength conversion element, light source device, vehicle headlamp, display device, light source module, and projection device - Google Patents

Abstract

The present invention achieves a wavelength conversion element that controls the temperature increase in a fluorescent layer and exhibits improved fluorescence emission intensity. This wavelength conversion element comprises a fluorescent layer that has phosphor particles dispersed in a binder, the fluorescent layer having a first region and a second region, and the first region having a higher temperature than the second region due to the effect of excitation light, wherein the phosphor particles are constituted by a phosphor doped with a luminescent center element, and at least two from among the concentration of the luminescent center element, the size of the phosphor particles, and the volume ratio of the phosphor particles to the binder vary from the first region to the second region of the fluorescent layer.

Description

Wavelength conversion element, light source device, vehicle headlamp, display device, light source module, projection device

The present invention relates to a light source device and a wavelength conversion element used in the light source device.
This application claims priority based on Japanese Patent Application No. 2018-104904 for which it applied to Japan on May 31, 2018, and uses the content here.

It is known as a prior art that when a phosphor is irradiated with excitation light such as a blue laser, the phosphor emits fluorescence.

JP 2017-215507 A (published on December 7, 2017) International Publication No. 2014/203484 (Released on December 24, 2014) JP 2012-119193 A (released on June 21, 2012)

However, the prior art as described above has a problem that temperature quenching occurs due to heat generation when high-density excitation light enters the phosphor. In other words, when the phosphor is caused to emit light by a blue laser or the like, there is a problem that a desired fluorescence emission intensity cannot be obtained at the time of high output irradiation.

An object of one embodiment of the present invention is to adjust the temperature rise of a phosphor and contribute to an improvement in fluorescence emission intensity.

In order to solve the above problem, a wavelength conversion element according to one embodiment of the present invention includes a fluorescent layer in which phosphor particles are dispersed in a binder, and the fluorescent layer includes a first region, a second region, and a second region. A wavelength conversion element in which the first region has a higher temperature than the second region due to the influence of excitation light, and the phosphor particles are composed of a phosphor doped with an emission center element, At least two of the concentration of the luminescent center element, the size of the phosphor particles, and the volume ratio of the phosphor particles to the binder change from the first region to the second region of the phosphor layer. It is the composition which is done.

According to one embodiment of the present invention, it is possible to control the temperature rise of the fluorescent layer and contribute to the improvement of the fluorescence emission intensity.

It is the schematic which shows the wavelength conversion element which concerns on a prior art. It is a graph which shows the light density dependence of the peak intensity of a YAG: Ce fluorescent substance. It is the schematic which shows the wavelength conversion element which concerns on Embodiment 1 of this invention. It is the schematic which shows the wavelength conversion element which concerns on Embodiment 2 of this invention. It is the schematic which shows the wavelength conversion element which concerns on Embodiment 3 of this invention. It is the schematic which shows the wavelength conversion element which concerns on Embodiment 4 of this invention. It is the schematic which shows the wavelength conversion element which concerns on Embodiment 5, 6 of this invention. FIG. 8A is a schematic diagram illustrating a light source device according to Embodiment 7 of the present invention, and FIGS. 8B to 8E are schematic diagrams illustrating wavelength conversion elements mounted on the light source device. 9A to 9C are schematic views showing a light source device according to Embodiment 8 of the present invention.

FIG. 1 shows a configuration of a general wavelength conversion element 10. In general, the phosphor layer 12 is deposited on the substrate 11. In the reflective optical system, the phosphor layer 12 is irradiated with excitation light 14 emitted from the excitation light source 13, and the phosphor layer 12 emits fluorescence. When the phosphor is caused to emit light by a blue laser or the like, the problem that the desired fluorescence emission intensity cannot be obtained at the time of high output irradiation is disclosed in Patent Document 1, in which the volume density of the phosphor particles on the phosphor excitation light irradiation side is disclosed. A configuration has been proposed in which the height is made higher than the substrate side. However, in such a configuration, there is a problem that heat generation is large because the phosphor density on the excitation light irradiation side of the phosphor is high. That is, it is necessary to examine the temperature dependence of the luminous efficiency of the phosphor.

[Temperature dependence of luminous efficiency]
For the phosphor particles, a garnet-based material whose base material is alumina is used from the viewpoint of material cost, manufacturing cost, and optical characteristics. As the garnet-based material, YAG: Ce (yellow light emitting phosphor), LuAG: Ce (green light emitting phosphor), or the like is used. The garnet-based phosphor is composed of a material represented by the general formula (M _1-x RE _x ) ₃ Al ₅ O ₁₂ and includes both M and RE containing at least one element selected from a rare earth element group. It is done. In general, M is Sc, Y, Gd, Lu, and RE is at least one element of Ce, Eu, and Tb. It is also possible to substitute a part of Al with Ga. In other preferred embodiments, the phosphor particles are CaAlSiN ₃ : Eu, (Sr, Ca) AlSiN ₃ : Eu, (Ca, Y) _y S _{12- (m + n)} Al _{m + n On} N _16-n : Eu, It is preferably selected from the group consisting of Si _6-z Al _z O _z N _8-z : Eu, SrGa ₂ S ₄ : Eu, or CaS: Eu (where m, n, x, y, z are positive Is the number of). Note that the above is an example, and the phosphor particles used in the phosphor layer of one embodiment of the present invention are not limited to the above examples.

The Ce concentration (mol%) of one embodiment of the present invention is represented by x × 100 (mol%) in the above general formula.

The temperature dependence of the luminous efficiency of the phosphor will be described based on the external quantum efficiency of the YAG: Ce phosphor. As shown in FIG. 2A, the phosphor material in which Ce (cerium) is doped as a dopant in YAG (yttrium, aluminum, garnet), the temperature dependence of the luminous efficiency varies depending on the difference in the doping concentration of Ce. I can confirm.

When the phosphor is irradiated with excitation light, fluorescence emission is obtained, and at the same time, a part of the excitation light is converted into thermal energy, so the irradiation spot portion of the phosphor becomes high temperature. Thermal radiation can be generally described by the following equation.

Q = A · ε · σ · (T _A ^ 4-T _B ^ 4)
Here, Q is showing the radiation heat, A is the radiation unit area, epsilon emissivity, sigma is the Stefan-Boltzmann constant, T _A is the temperature of the radiating portion, T _B is the temperature of the surroundings.

It is known that the luminous efficiency of the phosphor is affected by the temperature of the phosphor, and as shown in FIG. 2 (a), the luminous efficiency decreases as the temperature increases as the irradiation density increases. In order to obtain stronger (brighter) fluorescent light emission, it is necessary to increase the irradiation intensity of the excitation light 14, and in this case, the temperature rise of the phosphor layer 12 may not be sufficiently suppressed depending on the cooling state.

Further, it is known that the temperature characteristics of the phosphor change depending on the concentration of the luminescent center element (Ce in the present embodiment) (FIG. 2A). In general, a commercially available YAG: Ce phosphor has a Ce concentration with a high luminous efficiency (for example, about 1.4 to 1.5 mol%) when used at room temperature. This is because the YAG phosphor with a low Ce concentration has a high internal quantum efficiency, but the absorption rate of the excitation light is low. Therefore, the external quantum efficiency that is important as a wavelength conversion element is optimum when the Ce concentration is around 1.5 mol%. It is because it becomes. In the case where the phosphor temperature of the irradiation spot exceeds 250 ° C. due to irradiation with high-density and high-intensity excitation light, the luminous efficiency decreases with a general YAG: Ce phosphor (Ce concentration 1.4 mol%). . Here, a YAG: Ce phosphor having a low Ce concentration (for example, about 0.5 to 1.0 mol%) will be examined in more detail. Referring to FIG. 2A, it can be confirmed that when the Ce concentration is 1.0 mol% or more, the luminance is lowered at an optical density of 10 W / mm ² or more. On the other hand, if the Ce concentration is about 0.5 to 0.7 mol%, no decrease in luminance can be confirmed until the light density is about 16 W / mm ² . Thereby, it can be understood that when the Ce concentration is 1.0 mol% or more, the luminance is lowered due to the high temperature due to the excitation light and the phosphor having poor temperature characteristics.

FIG. 2B shows the temperature dependence due to the difference in the thickness of the phosphor layer. In either case, a phosphor having a Ce concentration of 0.7 mol% and an average particle diameter D50 of 11.1 μm is used as a sample. When the thickness of the phosphor layer is 20 μm to 40 μm, a decrease in luminance cannot be confirmed at least until the light density is about 16 W / mm ² . On the other hand, when the thickness of the phosphor layer is 70 μm, a decrease in luminance is confirmed at a light density of 12 W / mm ² or more. When the thickness of the phosphor layer is 100 μm, a significant decrease in luminance is confirmed at a light density of 5.5 W / mm ² or more. When the phosphor layer is thick, it can be confirmed that the heat radiation to the substrate is not in time, the surface temperature becomes high, and the luminance is lowered. In view of these tendencies, the present invention will be described for each embodiment.

Embodiment 1
[Configuration of wavelength conversion element]
Hereinafter, an embodiment of the present invention will be described in detail. FIG. 3A shows a schematic diagram of the wavelength conversion element 30a according to the first embodiment of the present invention. The configuration of the phosphor layer is different from the configuration of the general wavelength conversion element 10 shown in FIG. In the phosphor layer of the wavelength conversion element 30a according to the first embodiment, a YAG phosphor layer doped with a high Ce concentration is deposited on a substrate 11, and a YAG phosphor layer doped with a low Ce concentration is deposited thereon. Has been. Specifically, in the high Ce concentration doped YAG phosphor layer, the high Ce concentration doped YAG phosphor 36 a is scattered in the binder 35. Specifically, in the YAG phosphor layer doped with low Ce concentration, the low Ce concentration doped YAG phosphor particles 34 a are scattered in the binder 33. The binders used for the binders 33 and 35 may be the same material binder or different material binders.

That is, the phosphor layer on the surface irradiated with the excitation light 14 has a structure in which the concentration of Ce, which is the emission center element, is lower than that of the phosphor layer on the substrate side. Hereinafter, the side irradiated with the excitation light 14 is referred to as a “first region” (first region 31 in the first embodiment), and the other side is a second region (second region 32 in the first embodiment). Called. In this example, an example in which the phosphor layer is composed of at least two regions (first region 31 and second region 32) having different Ce concentrations is shown. A multilayer structure may be used. When the phosphor layer has a multilayer structure, the layer deposited on the substrate 11 corresponds to the second region, and the irradiation surface side irradiated with the excitation light 14 corresponds to the first region.

Phosphors with good luminous efficiency in the first region 31 and the second region 32 constituting the respective temperature ranges (low Ce concentration doped YAG phosphor particles 34a, 34b, high Ce concentration doped YAG phosphor particles 36a, 36b) Can be obtained. Thereby, compared with the case where the single fluorescent substance layer 12 is used, the light source device which is bright and long-life can be implement | achieved.

Further, as shown in FIG. 3A, the volume ratio of the phosphor particles to the binder is preferably larger in the first region 31 than in the second region 32. It is preferable that the change in the volume ratio relative to the binder not only changes discontinuously in the two regions, but also gradually changes so that the volume ratio decreases from the first region to the second region.

Since a temperature gradient is generated due to a temperature difference between the excitation light irradiation surface (first region 31 in the first embodiment) and the substrate side (second region 32 in the first embodiment), heat conduction in the second region 32 is performed. If it is good, heat can be released to the substrate side. Therefore, the first region 31 can release heat even if the binder density per unit volume is low.

FIG. 3B is a schematic diagram of the wavelength conversion element 30b according to the first embodiment of the present invention. For convenience of explanation, members having the same functions as those described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated. The difference from the wavelength conversion element 30a is that the particle diameters of the phosphors scattered in the first region 31 and the second region 32 are different. In a preferred embodiment, phosphor particles 34 b having a large particle size are scattered in the binder 33 in the first region 31, and phosphor particles 36 b having a small particle size are scattered in the binder 35 in the second region 32. . For convenience of explanation, the low Ce concentration doped YAG phosphor particles are indicated as “34 *” and the high Ce concentration doped YAG phosphor particles are indicated as “36 *” (“*” is “a” or “b”). . When the phosphor particles have a large particle size, “34b” is displayed, and when the phosphor particles have a small particle size, “36b” is displayed.

As shown in FIG. 3B as well as in FIG. 3A, the volume ratio of the phosphor particles to the binder is preferably larger in the first region 31 than in the second region 32. It is preferable that the change in the volume ratio relative to the binder not only changes so as to be divided in two regions, but also gradually changes so that the volume ratio decreases from the first region to the second region.

[Manufacturing process of wavelength conversion element]
The substrate 11 can be an aluminum substrate. In order to increase the fluorescence emission intensity, it is preferable that a highly reflective film such as silver is coated on the aluminum substrate. In other embodiments, a highly reflective alumina substrate, a white fully scattering substrate, or the like may be used. The material of the substrate 11 is preferably a material having a high thermal conductivity such as a metal, and is not particularly limited to the materials described above.

As the coating method, screen printing, sedimentation coating, or dip method can be used. As the binder, α-alumina, alumina sol, silica, colloidal silica, silicon carbide, zirconia, zirconium carbide, zirconium nitride, alkali metal silicate, titania, titanium carbide, titanium nitride can be used.

A high Ce concentration YAG phosphor layer serving as a second layer (corresponding to the second region) is applied on the substrate 11, and then a low Ce concentration YAG serving as the first layer (corresponding to the first region). A phosphor layer is applied. The manufacturing method is not limited to sedimentation coating, and other methods may be used. As an example of a yellow phosphor in which YAG is doped with Ce, the first layer can be coated with a YAG phosphor having a Ce concentration of 0.5 mol% in a film thickness of 40 μm. The second layer can be coated with a YAG phosphor having a Ce concentration of 1.5 mol% in a film thickness of 44 μm (FIG. 3A).

In a further preferred embodiment shown in FIG. 3B, the first layer can be coated with a YAG phosphor having a Ce concentration of 0.5 mol% in a film thickness of 40 μm. The volume ratio of the phosphor to the binder is preferably phosphor: binder = 1: 1, and the particle size distribution is preferably D50: 12.5 μm. The second layer can be coated with a YAG phosphor having a Ce concentration of 1.5 mol% in a film thickness of 44 μm. The volume ratio of the phosphor to the binder is preferably phosphor: binder = 1: 3, and the particle size distribution is preferably D50: 11 μm (FIG. 3B).

FIG. 2 (c) shows the light density dependence of the peak luminance comparing Sample 1 and Comparative Example 1 having such a configuration. In the configuration of Comparative Example 1, a YAG phosphor having a Ce concentration of 0.7 mol% is applied with a film thickness of 70 μm, and the volume ratio of the phosphor to the binder is phosphor: binder = 1: 1. As is clear from this comparison, it can be confirmed that the peak intensity of Sample 1 is exhibited at a higher light density than that of Comparative Example 1.

The preferred embodiment of the thickness of the first layer depends on the excitation light energy density. In a preferred embodiment, the maximum thickness of the first layer is less than 70 μm. The thinnest preferred embodiment is preferably about 1 μm as a monolayer for one phosphor particle.

In a preferred embodiment, a phosphor layer having a total film thickness of about 84 μm can be formed. The number of layers is not limited to two, and may be composed of three or more layers.

The phosphor layer may have a Ce concentration gradient. The Ce concentration gradient YAG phosphor layer is configured such that the Ce concentration on the substrate 11 side (corresponding to the second region) is high and the Ce concentration on the excitation light irradiation surface side (corresponding to the first region) is low.

In any case, by providing phosphors with different emission central element concentrations on the excitation light irradiation surface side and the substrate side, it is possible to obtain light emission with a phosphor with good luminous efficiency in each temperature range, and a single fluorescence A bright light source device can be realized as compared with the case of using a body.

[Embodiment 2]
Another embodiment of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated.

[Configuration of wavelength conversion element]
4A and 4B are schematic views of wavelength conversion elements 40a and 40b according to the second embodiment of the present invention. A difference from the wavelength conversion elements 30a and 30b in FIGS. 3A and 3B is that a recess having a semicircular cross section is formed in a part of the upper surface of the second region 42, and the first recess is formed in the recess. The region 41 is formed.

If the shape of the recess is semicircular, the distance from the high-density excitation light irradiation position is equal at the boundary line between the first region 41 and the second region 42, and the influence of heat can be equally dispersed. it can.

In a preferred embodiment, after forming the second region 42, it is preferable to form a groove (a recess having a semicircular cross-sectional shape) with a stamper and apply the first region 41.

[Embodiment 3]
Another embodiment of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated.

[Configuration of wavelength conversion element]
5A and 5B are schematic views of wavelength conversion elements 50a and 50b according to Embodiment 3 of the present invention. 3A and 3B is different from the wavelength conversion elements 30a and 30b in FIGS. 3A and 3B in that a recess having an inverted triangular shape is formed in a part of the upper surface of the second region 52, and the first recess is formed in the recess. That is, the region 51 is formed. By providing the shape of the recess, the influence of heat can be dispersed more than the multilayer film structure of the first embodiment.

In a preferred embodiment, after forming the second region 52, it is preferable to form a groove (a concave portion having an inverted triangular cross section) with a stamper, and apply the first region 51.

[Embodiment 4]
Another embodiment of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated.

[Configuration of wavelength conversion element]
6A and 6B are schematic views of wavelength conversion elements 60a and 60b according to Embodiment 4 of the present invention. 3A and 3B is different from the wavelength conversion elements 30a and 30b in FIG. 3A in that a concave portion having a square cross section is formed in a part of the upper surface of the second region 62, and the first concave portion is formed in the concave portion. A region 61 is formed. By providing the shape of the recess, the influence of heat can be dispersed more than the multilayer film structure of the first embodiment.

In a preferred embodiment, after forming the second region 62, it is preferable to form a groove (a recess having a square cross-sectional shape) with a stamper and apply the first region 61.

[Embodiments 5 and 6]
Another embodiment of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated.

[Mounting example of wavelength conversion element]
7A to 7D are schematic views of wavelength conversion elements 70a to 70d according to Embodiments 5 and 6 of the present invention. A high Ce concentration YAG phosphor layer is deposited on the transmissive substrate 71 (corresponding to the second regions 32, 42, 52, and 62), and a low Ce concentration YAG phosphor layer is deposited thereon (the first region). Corresponding to the regions 31, 41, 51, 61). It is also preferable that the transparent substrate 71 has a heat sink structure. In another preferred embodiment, the transmissive substrate 71 can be cooled by making a fixed contact with a transmissive heat sink (not shown).

In FIG. 7, the phosphor particles (low Ce concentration doped YAG phosphor particles 34a and 34b, high Ce concentration doped YAG phosphor particles 36a and 36b) are omitted for simplification in both the first region and the second region. ing. In FIG. 7A, phosphor particles (low Ce concentration doped YAG phosphor particles in the binders 33 and 35 as in the first region 31 and the second region 32 shown in FIGS. 3A and 3B). 34a, 34b, high Ce concentration doped YAG phosphor particles 36a, 36b) are preferably interspersed. Similarly, in FIG. 7B, phosphor particles (low Ce concentration doped YAG in the binders 33 and 35 as in the first region 41 and the second region 42 shown in FIGS. 4A and 4B). It is preferred that the phosphor particles 34a, 34b and the high Ce concentration doped YAG phosphor particles 36a, 36b) are interspersed. Similarly, in FIG. 7C, phosphor particles (low Ce concentration doped YAG fluorescence) are contained in the binders 33 and 35 in the same manner as the first region 51 and the second region 52 shown in FIGS. 5A and 5B. Preferably, the body particles 34a, 34b and the high Ce concentration doped YAG phosphor particles 36a, 36b) are interspersed. Similarly, in FIG. 7 (d), phosphor particles (low Ce concentration doped YAG fluorescence) are contained in the binders 33 and 35 in the same manner as the first region 61 and the second region 62 shown in FIGS. 6 (a) and 6 (b). Preferably, the body particles 34a, 34b and the high Ce concentration doped YAG phosphor particles 36a, 36b) are interspersed.

In the fifth embodiment of the present invention, a transmissive light source device that irradiates the excitation light 14 from below the transmissive substrate 71 is preferable. Such a light source device is preferably mounted on a transmissive laser headlight (Patent Document 2 (International Publication No. 2014/203484)). As disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 2012-119193), when a fluorescent film is deposited on a transmissive heat sink substrate, when the excitation light is incident from the heat sink side, the heat sink side has heat dissipation properties. It is known to be expensive. When the transparent substrate 71 used for the wavelength conversion elements 70a to 70d has a heat sink function, a high Ce concentration YAG phosphor layer is deposited on the irradiation surface side (second region) irradiated with excitation light. Is preferred. Excitation light is irradiated from the irradiation surface side (second region), and the heat of the irradiation surface (second region) is dissipated to the transmissive substrate 71, so that the first region has a higher temperature than the second region. Therefore, it is preferable that a low Ce concentration YAG phosphor layer is deposited in the first region.

In the sixth embodiment of the present invention, it is preferable that the excitation light 14 is light from a backlight device (not shown). The excitation light emitted from the light source of the backlight device is preferably mounted on a display device that transmits the fluorescent light by the wavelength conversion elements 70a to 70d through the transparent substrate 71.

In Embodiments 5 and 6, not only a change in the concentration of Ce as a dopant, but also a phosphor layer in which the particle size of the phosphor particles and the volume density of the phosphor particles with respect to the binder are different may be used.

[Embodiment 7]
Another embodiment of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated.

[Configuration of light source device]
FIG. 8A shows a schematic diagram of a light source device 80 according to Embodiment 7 of the present invention. The light source device 80 is preferably a reflective laser headlight 80. The excitation light source 13 is preferably a blue laser light source that emits excitation light 14 having a wavelength for exciting the phosphor layer of the wavelength conversion element 81. The reflector 111 is preferably composed of a semiparabolic mirror. It is preferable that the paraboloid is divided into upper and lower parts parallel to the xy plane to form a semiparaboloid, and the inner surface is a mirror. The reflector 111 has a through hole through which the excitation light 14 passes. The wavelength conversion element 81 is excited by the blue excitation light 14 and emits fluorescence emission 117 in the long wavelength range (yellow wavelength) of visible light. Further, the excitation light 14 strikes the wavelength conversion element 81 and becomes diffuse reflection light 118. The wavelength conversion element 81 is disposed at the focal point of the paraboloid. Since the wavelength conversion element 81 is located at the focal point of the parabolic mirror, when the fluorescent light emission 117 and the diffuse reflection light 118 emitted from the wavelength conversion element 81 strike the reflector 111 and are reflected, they uniformly reach the emission surface 112. Go straight. White light in which fluorescent light emission 117 and diffuse reflected light 118 are mixed is emitted from the emission surface 112 as parallel light.

8B to 8E are schematic views of the wavelength conversion element 81 arranged at the focal point of the paraboloid. In the wavelength conversion elements 81a to 81d, the layer on the irradiation surface side of the excitation light ( first regions 31, 41, 51, 61) is formed of a low Ce concentration YAG phosphor layer, and the layer on the substrate side (second region) 32, 42, 52, 62) are composed of high Ce concentration YAG phosphor layers.

In FIGS. 8B to 8E, both the first region and the second region are phosphor particles (low Ce concentration doped YAG phosphor particles 34a and 34b, high Ce concentration doped YAG phosphor particles for simplification). 36a and 36b) are omitted. In FIG. 8B, phosphor particles (low Ce concentration doped YAG phosphor particles in the binders 33 and 35 as in the first region 31 and the second region 32 shown in FIGS. 3A and 3B). 34a, 34b, high Ce concentration doped YAG phosphor particles 36a, 36b) are preferably interspersed. Similarly, in FIG. 8C, phosphor particles (low Ce concentration doped YAG in the binders 33 and 35 as in the first region 41 and the second region 42 shown in FIGS. 4A and 4B). It is preferred that the phosphor particles 34a, 34b and the high Ce concentration doped YAG phosphor particles 36a, 36b) are interspersed. Similarly, in FIG. 8D, similarly to the first region 51 and the second region 52 shown in FIGS. 5A and 5B, phosphor particles (low Ce concentration doped YAG fluorescence) are contained in the binders 33 and 35. Preferably, the body particles 34a, 34b and the high Ce concentration doped YAG phosphor particles 36a, 36b) are interspersed. Similarly, in FIG. 8E, phosphor particles (low Ce concentration doped YAG fluorescence) are contained in the binders 33 and 35 in the same manner as the first region 61 and the second region 62 shown in FIGS. 6A and 6B. Preferably, the body particles 34a, 34b and the high Ce concentration doped YAG phosphor particles 36a, 36b) are interspersed.

By disposing the low Ce concentration YAG phosphor layer on the layer on the irradiation surface side of the excitation light ( first regions 31, 41, 51, 61), light emission with higher luminance than that of the prior art becomes possible.

In the seventh embodiment, not only a change in the concentration of Ce as a dopant, but also a phosphor layer having a different particle size and a volume density of the phosphor particles with respect to the binder may be used.

[Embodiment 8]
Another embodiment of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated.

[Configuration of Projector]
FIG. 9A shows a schematic diagram of a projection apparatus 90 using the light source module 91 according to the eighth embodiment. The projection device 90 can be preferably used for a projector or the like. In the projection device 90, the excitation light source 13 is preferably a laser light source that emits excitation light 14 having a wavelength for exciting the phosphor layer 148 (see FIGS. 9B and 9C) in the light source module 91. In a preferred embodiment, a blue laser diode that excites a phosphor such as YAG or LuAG is used. The excitation light 14 that irradiates the phosphor layer 148 can pass through the light source side optical system 106 and the mirrors 109a to 109c on the optical path. The light source side optical system 106 is preferably a dichroic mirror. A preferred dichroic mirror can reflect blue light incident at 45 degrees and transmit red and green light.

The phosphor layer 148 is deposited on the phosphor wheel 141. FIG. 9B shows a plan view (xy plane) of the light source module 91, and FIG. 9C shows a cross-sectional view (xz plane) of the light source module 91. In a preferred embodiment, the light source module 91 includes a phosphor layer 148 deposited on the periphery on the surface of the phosphor wheel 141. The fluorescent wheel 141 is fixed to the rotating shaft 147 of the driving device 142 by a wheel fixture 146. The driving device 142 is preferably a motor, and a fluorescent wheel 141 fixed to a rotating shaft 147 that is a rotating shaft of the motor by a fixing tool 146 rotates as the motor rotates.

The phosphor layer 148 deposited on the peripheral part on the surface of the fluorescent wheel 141 receives the excitation light and emits the fluorescent light emission 117, passes through the light source side optical system 106, and emits the fluorescent light. Since the phosphor layer 148 rotates with the rotation of the fluorescent wheel 141, the phosphor layer 148 emits the fluorescence emission 117 while rotating at any time.

In a preferred embodiment, the phosphor layer 148 has a configuration in the xz plane of FIGS. 8B to 8E, with the cross section in the xz plane of FIG. 9C. It is preferable that any cross section of any xz plane perpendicular to the xy plane of FIG. 9B has the configuration in the xz plane of FIGS. 8B to 8E. In the configuration in which the phosphor layer 148 corresponds to the wavelength conversion element 81a, the phosphor layer 148 has the second layer (second region 32) deposited on the phosphor wheel 141, and the first layer ( A multilayer structure in which the first region 31) is deposited is formed. In the configuration in which the phosphor layer 148 corresponds to the wavelength conversion elements 81b to 81d, concave portions are formed in the second regions 42, 52, and 62 in an annular shape. The cross-sectional shapes of the recesses are preferably semicircular, inverted triangular, and square, respectively. The first regions 41, 51 and 61 are preferably formed in an annular recess having such a cross-sectional shape.

In the eighth embodiment, not only a change in the concentration of Ce as a dopant from the first region to the second region, but also a phosphor layer in which the particle size of the phosphor particles and the volume density of the phosphor particles with respect to the binder are different may be used. Good.

In a preferred embodiment, the projector (projection device 90) can include the light source module 91, the display element 107, the light source side optical system 106 (dichroic mirror), and the projection side optical system 108. The light source side optical system 106 (dichroic mirror) guides the light from the light source module 91 to the display element 107, and the projection side optical system 108 projects the projection light from the display element 107 onto a screen or the like. it can. In a preferred embodiment, the display element 107 is preferably a DMD (Digital Mirror Device). The projection-side optical system 108 is preferably composed of a combination of projection unit lenses.

[Summary]
The wavelength conversion element (30a, 30b, 40a, 50a, 60a, 70a, 81, 81a, 81b, 81c, 81d) according to the aspect 1 of the present invention includes phosphor particles (low Ce concentration) in the binder (33, 35). A phosphor layer in which doped YAG phosphor particles 34a and 34b (phosphor particles having a large particle diameter) and high Ce concentration doped YAG phosphor particles 36a and 36b (phosphor particles having a small particle diameter) are dispersed; Has a first region (31, 41, 51, 61) and a second region (32, 42, 52, 62), and the second region (32, 42, 52, 62) The wavelength conversion elements (30a, 30b, 40a, 50a, 60a, 70a, 81, 81a, 81b, 81c, 81d) in which the first region (31, 41, 51, 61) is at a higher temperature. ) The phosphor particles (low Ce concentration doped YAG phosphor particles 34a and 34b (phosphor particles having a large particle diameter), high Ce concentration doped YAG phosphor particles 36a and 36b (phosphor particles having a small particle diameter)) emit light. The phosphor is doped with a central element (Ce), and extends from the first region (31, 41, 51, 61) of the phosphor layer to the second region (32, 42, 52, 62). Concentration of luminescent center element (Ce), phosphor particles (low Ce concentration doped YAG phosphor particles 34a, 34b (large particle size phosphor particles), high Ce concentration doped YAG phosphor particles 36a, 36b (small particle size) And phosphor particles (low Ce concentration doped YAG phosphor particles 34a and 34b (phosphor particles having a large particle diameter) with respect to the binder (33, 35) Is configured configured high Ce doped YAG phosphor particles 36a, 36b at least two volume ratio of (small phosphor particles with a particle size)) changes.

According to the above configuration, the temperature rise of the fluorescent layer can be controlled.

In the wavelength conversion element according to aspect 2 of the present invention, in the aspect 1, the change in size of the phosphor particles is a change in which the volume decreases from the first region to the second region. Also good.

According to the above configuration, the heat dissipation can be adjusted by adjusting the particle size, and the color unevenness on the light emitting surface can be reduced by using a phosphor having a small particle size on the light emitting surface.

In the wavelength conversion element according to aspect 3 of the present invention, in the aspect 1 or 2, the change in the concentration of the luminescent center element is a change in which the concentration increases from the first region to the second region. It is good.

The wavelength conversion element according to Aspect 4 of the present invention is the wavelength conversion element according to any one of Aspects 1 to 3, wherein the volume ratio of the phosphor particles to the binder is changed from the first area to the second area. It is good also as a structure which is a change which decreases.

According to the above configuration, the heat dissipation can be adjusted by the amount of the binder, and a high-intensity wavelength conversion element can be provided.

The wavelength conversion element according to aspect 5 of the present invention is the wavelength conversion element according to any one of aspects 1 to 4, wherein the first region has a layer structure including a first layer, and the second region is a second layer. The first layer may be deposited on the second layer, and the maximum thickness of the first layer may be less than 70 μm.

According to the above configuration, a preferable film thickness depending on the excitation light energy density can be adjusted, and a high-intensity wavelength conversion element can be provided.

The wavelength conversion element according to Aspect 6 of the present invention is the wavelength conversion element according to any one of Aspects 1 to 4, wherein the second region has a recess in the excitation light irradiation region, and the first region is in the recess. It is good also as a structure which is formed and the said 1st area | region is irradiated with excitation light.

According to the above configuration, the heat radiation distance from the irradiation point can be adjusted, and a high-intensity wavelength conversion element can be provided.

A light source device according to aspect 7 of the present invention includes the wavelength conversion element according to any one of aspects 1 to 6 and a substrate, wherein the fluorescent layer is deposited on the substrate, and the fluorescent layer is The first surface and the second surface are opposite to each other in the thickness direction, the second region is at least on the second surface side, and the first region is only on the first surface side. The second region may face the substrate, and the first region may be heated to a higher temperature than the second region by irradiating the first region with excitation light.

According to the above configuration, it is possible to provide fluorescent light emission with higher brightness than conventional.

A light source device according to an eighth aspect of the present invention includes the wavelength conversion element according to any one of the first to sixth aspects, and a transmissive heat sink substrate (71), and the fluorescent layer on the transmissive heat sink substrate. And the fluorescent layer has a first surface and a second surface that are opposite to each other in the thickness direction, and the second region is at least on the second surface side, The region is only on the first surface side, the second surface faces the transmissive heat sink substrate, the excitation light is irradiated from the second surface side, and the heat of the second surface is transmitted through the transmission surface. It is good also as a structure from which the said 1st area | region becomes higher temperature than the said 2nd area | region by thermally radiating to a heat sink board | substrate.

According to the above configuration, it is possible to provide fluorescent light emission with higher brightness than conventional.

A vehicle headlamp (reflection type laser headlight 80) according to Aspect 9 of the present invention is a vehicle headlamp provided with the light source device according to Aspect 7 or 8, and emits excitation light. A light source, a light source device according to the above aspect 7 or 8 that is excited by excitation light emitted from the light source and emits fluorescent light, a reflector having a reflective surface that reflects the fluorescent light emitted from the light source device, and The reflecting surface of the reflector may be configured to reflect the incident light so as to be emitted in parallel in a certain direction.

According to the above configuration, it is possible to provide a vehicular headlamp that has higher brightness than conventional ones.

The display device according to aspect 10 of the present invention includes a backlight device including a light source that emits excitation light, and the above-described aspect 7 that emits fluorescent light by being excited by excitation light emitted from the light source of the backlight device. The light source device described in 8 may be provided.

According to the above configuration, it is possible to provide a display device with higher brightness than in the past.

A light source module (90) according to aspect 11 of the present invention includes the wavelength conversion element according to any one of aspects 1 to 6 and a fluorescent wheel (141), and the light source module (90) is provided on the fluorescent wheel (141). A fluorescent layer is deposited, the fluorescent layer has a first surface and a second surface facing each other in the thickness direction, and the second region is at least on the second surface side, and the first surface The region is only on the first surface side, the second surface faces the fluorescent wheel, and the first surface side is irradiated with excitation light from the first region to the first surface. It is good also as a structure where an area | region becomes high temperature.

According to the above configuration, it is possible to provide a light source module with higher brightness than conventional.

A projection apparatus (90; projector) according to aspect 12 of the present invention includes a light source module (91) according to aspect 11 above, and a light source (13) that emits excitation light (14) to the light source module (91). A light source device including a drive device (142) for rotating a fluorescent wheel (141) of the light source module (91), a display element (107), and light from the light source device for the display element (107). A light source side optical system (106) that guides light to the screen and a projection side optical system (108) that projects projection light from the display element (107) onto a screen or the like may be used.

According to the above configuration, it is possible to provide a projection device with higher brightness than in the past.

The wavelength conversion element according to aspect 13 of the present invention may be configured such that, in the above aspect 6, the cross-sectional shape of the concave portion can be selected from any of a semicircular shape, an inverted triangular shape, and a rectangular shape. .

According to the above configuration, the heat radiation distance from the irradiation point can be adjusted, and a high-intensity wavelength conversion element can be provided.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

Claims (12)

1. A phosphor layer in which phosphor particles are dispersed in a binder,
   The fluorescent layer has a first region and a second region, and is a wavelength conversion element in which the first region has a higher temperature than the second region due to the influence of excitation light,
   The phosphor particles are composed of a phosphor doped with an emission center element,
   At least two of the concentration of the luminescent center element, the size of the phosphor particles, and the volume ratio of the phosphor particles to the binder change from the first region to the second region of the phosphor layer. The wavelength conversion element characterized by the above-mentioned.
2. 2. The wavelength conversion element according to claim 1, wherein the change in size of the phosphor particles is a change in which the volume decreases from the first region to the second region.
3. 3. The wavelength conversion element according to claim 1, wherein the change in the concentration of the luminescent center element is a change in which the concentration increases from the first region to the second region.
4. The change in the volume ratio of the phosphor particles with respect to the binder is a change in which the volume ratio decreases from the first region to the second region. Wavelength conversion element.
5. The first region has a layer structure composed of a first layer, the second region has a layer structure composed of a second layer,
   The first layer is deposited on the second layer;
   5. The wavelength conversion element according to claim 1, wherein a maximum thickness of the first layer is less than 70 μm.
6. The second region has a recess in the excitation light irradiation region;
   The first region is formed in the recess;
   The wavelength conversion element according to any one of claims 1 to 4, wherein the first region is irradiated with excitation light.
7. The wavelength conversion element according to any one of claims 1 to 6,
   A substrate,
   With
   The phosphor layer is deposited on the substrate;
   The fluorescent layer has a first surface and a second surface opposite to each other in the thickness direction, the second region is at least on the second surface side, and the first region is a first surface 1 only on the face side,
   The second surface faces the substrate;
   The light source device according to claim 1, wherein the first region is heated to a higher temperature than the second region when the first region is irradiated with excitation light.
8. The wavelength conversion element according to any one of claims 1 to 6,
   A transparent heat sink substrate;
   With
   The phosphor layer is deposited on the transparent heat sink substrate;
   The fluorescent layer has a first surface and a second surface opposite to each other in the thickness direction, the second region is at least on the second surface side, and the first region is a first surface 1 only on the face side,
   The second surface faces the transparent heat sink substrate;
   Excitation light is irradiated from the second surface side, and the heat of the second surface is radiated to the transmissive heat sink substrate, whereby the first region becomes hotter than the second region. Light source device.
9. A vehicle headlamp provided with the light source device according to claim 7 or 8,
   A light source that emits excitation light;
   The light source device according to claim 7 or 8, wherein the light source device is excited by excitation light emitted from the light source and emits fluorescent light.
   A reflector having a reflecting surface for reflecting the fluorescent light emitted from the light source device;
   With
   The vehicle headlamp according to claim 1, wherein the reflecting surface of the reflector reflects the incident light so as to be emitted in parallel in a certain direction.
10. A backlight device including a light source that emits excitation light;
    The light source device according to claim 7 or 8, which is excited by excitation light emitted from a light source of the backlight device and emits fluorescent light,
    A display device comprising:
11. The wavelength conversion element according to any one of claims 1 to 6,
    With a fluorescent wheel,
    With
    The phosphor layer is deposited on the phosphor wheel;
    The fluorescent layer has a first surface and a second surface facing each other in the thickness direction, the second region is at least on the second surface side, and the first region is the first surface On the face side only,
    The second surface faces the fluorescent wheel;
    The light source module according to claim 1, wherein the first region has a higher temperature than the second region when irradiated with excitation light from the first surface side.
12. The light source module according to claim 11;
    A light source that emits excitation light to the light source module;
    A driving device for rotating a fluorescent wheel of the light source module;
    A light source device comprising:
    A display element;
    A light source side optical system that guides light from the light source device to the display element;
    A projection-side optical system that projects projection light from the display element onto a screen or the like;
    A projection apparatus comprising:

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