JP2022112662A - Light source device and projector - Google Patents

Abstract

To provide a light source device that can efficiently generate illumination light, and a projector.SOLUTION: A light source device of the present invention comprises: an excitation light source that radiates excitation light; a ceramic phosphor that converts a wavelength of part of the excitation light radiated from the excitation light source and incident on a first surface to generate fluorescent light and emits at least the fluorescent light from a second surface different from the first surface; and a substrate that supports the ceramic phosphor. The ceramic phosphor includes a plurality of pores, and surface roughness of the first surface is rougher than surface roughness of the second surface.SELECTED DRAWING: Figure 3

Description

The present invention relates to a light source device and a projector.

2. Description of the Related Art Conventionally, there has been proposed a light source device that utilizes fluorescence emitted from a phosphor when the phosphor is irradiated with excitation light emitted from a light source. Patent Literature 1 listed below discloses a reflective phosphor unit that emits fluorescence from a surface on which excitation light is incident. Patent Literature 2 listed below discloses a transmissive phosphor unit that emits fluorescence from a surface opposite to the surface on which excitation light is incident.

JP 2016-70947 A JP 2012-3923 A

In the phosphor unit of Patent Document 1, since the light exit surface of the phosphor is formed in a uniform plane, the light is refracted when emitted from the light exit surface and the light emitting area is expanded, resulting in an increase in the light emitting area. There is a problem that the light utilization efficiency is lowered because it cannot be efficiently incorporated into the system. In addition, in the phosphor unit of Patent Document 2, since the excitation light enters the phosphor through the transparent substrate, part of the excitation light reflected at the interface between the phosphor and the transparent substrate is reflected inside the transparent substrate. There is a problem that it becomes stray light and the light utilization efficiency is lowered.

In order to solve the above problems, a light source device of one embodiment of the present invention includes an excitation light source that emits excitation light; and a substrate supporting the ceramic phosphor, wherein the ceramic phosphor has a plurality of pores. and the surface roughness of the first surface is rougher than the surface roughness of the second surface.

A projector according to one aspect of the present invention includes the light source device, a light modulation device that modulates light emitted from the light source device according to image information to form image light, and a projection optical device that projects the image light. and.

1 is a diagram showing a schematic configuration of a projector according to a first embodiment; FIG. It is a figure which shows schematic structure of a light source device. FIG. 3 is a cross-sectional view showing a configuration of a main part of a wavelength conversion element; FIG. 4 is an enlarged view showing the state of light emitted from the second surface of the ceramic phosphor; FIG. 10 is a cross-sectional view showing the main configuration of a wavelength conversion element according to a second embodiment; FIG. 10 is a cross-sectional view showing a configuration of a main part of a wavelength conversion element of a modified example;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In addition, in the drawings used in the following explanation, in order to make the features easier to understand, the characteristic portions may be enlarged for convenience, and the dimensional ratios of each component may not necessarily be the same as the actual ones. do not have.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a projector according to the first embodiment. FIG. 2 is a diagram showing a schematic configuration of the light source device.
As shown in FIG. 1, the projector 1 of this embodiment is a projection type image display device that displays an image on a screen SCR. The projector 1 includes a light source device 2 , a color separation optical system 3 , a light modulation device 4 R, a light modulation device 4 G, a light modulation device 4 B, a synthesizing optical system 5 and a projection optical device 6 .

The light source device 2 emits white illumination light WL toward the color separation optical system 3 .
The color separation optical system 3 separates the illumination light WL emitted from the light source device 2 into red light LR, green light LG, and blue light LB. The color separation optical system 3 includes a first dichroic mirror 7a and a second dichroic mirror 7b, a first total reflection mirror 8a, a second total reflection mirror 8b and a third total reflection mirror 8c, and a first It has a relay lens 9a and a second relay lens 9b.

The first dichroic mirror 7a separates the illumination light WL from the light source device 2 into red light LR and other lights (green light LG and blue light LB). The first dichroic mirror 7a transmits red light LR and reflects other light (green light LG and blue light LB). On the other hand, the second dichroic mirror 7b reflects the green light LG and transmits the blue light LB, thereby separating the other light (the green light LG and the blue light LB) into the green light LG and the blue light LB. .

The first total reflection mirror 8a is arranged in the optical path of the red light LR, and reflects the red light LR transmitted through the first dichroic mirror 7a toward the light modulator 4R. On the other hand, the second total reflection mirror 8b and the third total reflection mirror 8c are arranged in the optical path of the blue light LB, and guide the blue light LB transmitted through the second dichroic mirror 7b to the light modulator 4B. The green light LG is reflected from the second dichroic mirror 7b toward the light modulator 4G.

The first relay lens 9a and the second relay lens 9b are arranged on the light exit side of the second total reflection mirror 8b in the optical path of the blue light LB. The first relay lens 9a and the second relay lens 9b have the function of compensating for the optical loss of the blue light LB caused by the optical path length of the blue light LB being longer than the optical path lengths of the red light LR and the green light LG. have.

The light modulator 4R modulates the red light LR according to image information to form image light corresponding to the red light LR. The light modulator 4G modulates the green light LG according to image information to form image light corresponding to the green light LG. The light modulation device 4B modulates the blue light LB according to image information to form image light corresponding to the blue light LB.

Transmissive liquid crystal panels, for example, are used for the optical modulator 4R, the optical modulator 4G, and the optical modulator 4B. A polarizing plate (not shown) is arranged on each of the incident side and the exit side of the liquid crystal panel.

A field lens 10R, a field lens 10G, and a field lens 10B are arranged on the incident sides of the optical modulator 4R, the optical modulator 4G, and the optical modulator 4B, respectively. The field lens 10R, the field lens 10G, and the field lens 10B collimate the red light LR, the green light LG, and the blue light LB incident on the light modulator 4R, the light modulator 4G, and the light modulator 4B, respectively.

Image light from the optical modulators 4R, 4G, and 4B is incident on the combining optical system 5 . The synthesizing optical system 5 synthesizes image light corresponding to the red light LR, green light LG, and blue light LB, respectively, and emits the synthesized image light toward the projection optical device 6 . A cross dichroic prism, for example, is used for the synthesizing optical system 5 .

The projection optical device 6 consists of a group of projection lenses, and enlarges and projects the image light synthesized by the synthesis optical system 5 toward the screen SCR. As a result, an enlarged image is displayed on the screen SCR.

(light source device)
Next, the configuration of the light source device 2 will be described.
As shown in FIG. 2, the light source device 2 includes an excitation light source 10, an afocal optical system 11, a homogenizer optical system 12, a condensing optical system 13, a wavelength conversion element 20, a pickup optical system 30, and a uniform optical system. and an illumination optical system 80 .

The excitation light source 10 includes a plurality of semiconductor lasers 10a that emit blue excitation light E, which is laser light, and a plurality of collimator lenses 10b. A plurality of semiconductor lasers 10a are arranged in an array within one plane perpendicular to the illumination optical axis 100ax. The collimator lenses 10b are arranged in an array within one plane perpendicular to the illumination optical axis 100ax so as to correspond to each semiconductor laser 10a. The collimator lens 10b converts the excitation light E emitted from the corresponding semiconductor laser 10a into parallel light.

The afocal optical system 11 includes, for example, a convex lens 11a and a concave lens 11b. The afocal optical system 11 reduces the luminous flux diameter of the excitation light E, which is a parallel luminous flux emitted from the excitation light source 10 .

The homogenizer optical system 12 includes, for example, a first multilens array 12a and a second multilens array 12b. The homogenizer optical system 12 makes the light intensity distribution of the excitation light uniform on the wavelength conversion element 20 described later, ie, a so-called top-hat distribution. The homogenizer optical system 12 superimposes a plurality of small light beams emitted from the plurality of lenses of the first multi-lens array 12 a and the second multi-lens array 12 b on the wavelength conversion element 20 together with the condensing optical system 13 . As a result, the light intensity distribution of the excitation light E irradiated onto the wavelength conversion element 20 is made uniform.

The condensing optical system 13 includes, for example, a first lens 13a and a second lens 13b. In this embodiment, the first lens 13a and the second lens 13b are each composed of a convex lens. The condensing optical system 13 is arranged in the optical path from the homogenizer optical system 12 to the wavelength conversion element 20 , and condenses the excitation light E to enter the wavelength conversion element 20 . The configuration of the wavelength conversion element 20 will be described later.

The pickup optical system 30 includes, for example, a first collimator lens 31 and a second collimator lens 32 . The pickup optical system 30 is a parallelizing optical system that substantially parallelizes the light emitted from the wavelength conversion element 20 . The first collimating lens 31 and the second collimating lens 32 are each composed of a convex lens. The light collimated by the pickup optical system 30 enters the uniform illumination optical system 80 .

A uniform illumination optical system 80 includes a first lens array 81 , a second lens array 82 , a polarization conversion element 83 and a superimposing lens 84 .

The first lens array 81 has a plurality of first lenses 81a for splitting the illumination light WL from the light source device 2 into a plurality of partial light fluxes. The multiple first lenses 81a are arranged in a matrix in a plane perpendicular to the illumination optical axis 100ax.

The second lens array 82 has a plurality of second lenses 82 a corresponding to the plurality of first lenses 81 a of the first lens array 81 . The multiple second lenses 82a are arranged in a matrix in a plane perpendicular to the illumination optical axis 100ax.

The second lens array 82, together with the superimposing lens 84, focuses the images of the respective first lenses 81a of the first lens array 81 in the vicinity of the image forming regions of the light modulators 4R, 4G, and 4B. image.

The polarization conversion element 83 converts the light emitted from the second lens array 82 into linearly polarized light. The polarization conversion element 83 includes, for example, a polarization separation film and a retardation plate (not shown).

The superimposing lens 84 collects the partial light beams emitted from the polarization conversion element 83 and superimposes them near the image forming regions of the light modulators 4R, 4G, and 4B.

(Wavelength conversion element)
Next, the configuration of the wavelength conversion element 20 will be described.
FIG. 3 is a cross-sectional view showing the essential configuration of the wavelength conversion element 20. As shown in FIG. 3 corresponds to a cross section obtained by cutting the wavelength conversion element 20 along a plane including the illumination optical axis 100ax in FIG.

As shown in FIG. 3 , the wavelength conversion element 20 of this embodiment includes a substrate 21 , a ceramic phosphor 22 , a dichroic layer (optical layer) 23 and a joining member 24 . The wavelength conversion element 20 of this embodiment is a fixed type wavelength conversion element that does not change the incident position of the excitation light E with respect to the ceramic phosphor 22 with time.

The substrate 21 is made of a metal material such as aluminum or copper, which is excellent in heat dissipation. The substrate 21 is a support member that supports the ceramic phosphor 22 . The substrate 21 of this embodiment is made of a non-translucent member. The substrate 21 is made of, for example, a metal material such as aluminum or copper, which is excellent in heat dissipation. The substrate 21 of this embodiment has higher thermal conductivity than the ceramic phosphor 22 . The substrate 21 has a front surface (one surface) 21a and a back surface facing in opposite directions. A surface 21 a of the substrate 21 is a surface supporting the ceramic phosphor 22 .

The ceramic phosphor 22 has a first surface 22a and a second surface 22b different from the first surface 22a. The first surface 22a is the surface on which the excitation light E emitted from the excitation light source 10 is incident. The second surface 22b is the surface on which the fluorescence Y is emitted. The ceramic phosphor 22 of the present embodiment is a transmissive wavelength type that converts the wavelength of part of the excitation light E incident from the first surface 22a to generate fluorescence Y, and emits at least the fluorescence Y from the second surface 22b. It is a conversion element.

Ceramic phosphor 22 includes a phosphor phase 25 , a matrix phase 26 and a plurality of pores (scattering elements) 27 . Phosphor phase 25 contains an oxide phosphor to which an activator is added. The phosphor phase 25 contains, for example, yttrium aluminum garnet (YAG(Y ₃ Al ₅ O ₁₂ ):Ce) to which cerium (Ce) is added as an activator.

Taking YAG:Ce as an example, materials obtained by mixing raw material powders containing constituent elements such as Y ₂ O ₃ , Al ₂ O ₃ , and CeO ₃ as phosphor particles and causing a solid phase reaction, coprecipitation methods, sol-gel YAG particles obtained by a vapor phase method such as spray drying method, flame pyrolysis method, thermal plasma method and the like can be used.

The oxide phosphor constituting the phosphor phase 25 is Y ₃ Al ₅ O ₁₂ and at least one of Y ₃ (Al, Ga) ₅ O ₁₂ , Lu ₃ Al ₅ O ₁₂ and TbAl ₅ O ₁₂ . may contain Further, the phosphor phase 25 may contain europium (Eu) as an activator instead of cerium (Ce).

The matrix phase 26 functions as a binder that binds together the plurality of phosphor particles forming the phosphor phase 25 . The matrix phase 26 is composed of a material containing MgO (magnesium oxide) as translucent ceramics. The thermal conductivity of magnesium oxide forming the matrix phase 26 is approximately 50 W/m·K, and the thermal conductivity of YAG forming the phosphor phase 25 is approximately 12 W/m·K. In this embodiment, the matrix phase 26 contains translucent ceramics with higher thermal conductivity than the phosphor phase 25 .

The metal oxide constituting the matrix phase 26 contains at least one of Al ₂ O ₃ , ZnO, TiO ₂ , Y ₂ O ₃ , YAlO ₃ , BeO and MgAl ₂ O ₄ in addition to MgO. You can stay.

The thermal conductivity of Al ₂ O ₃ is approximately 30 W/m·K, the thermal conductivity of ZnO is approximately 25 W/m·K, and the thermal conductivity of TiO ₂ is approximately 43 W/m·K. , the thermal conductivity of Y ₂ O ₃ is about 27 W/m K, the thermal conductivity of YAlO ₃ is about 12 W/m K, the thermal conductivity of BeO is about 250 W/m K, The thermal conductivity of MgAl ₂ O ₄ is approximately 14 W/m·K.

A plurality of pores 27 are scattering elements for scattering excitation light E and fluorescence Y. FIG. The average diameter of the plurality of pores 27 is set to, for example, about 1 μm or less. The scattering elements are not limited to the pores 27, and may be particles or the like made of a material having a refractive index different from that of the phosphor.

Such a ceramic phosphor 22 can be manufactured, for example, by the following steps.
A predetermined amount of Al ₂ O ₃ powder, Y ₂ O ₃ powder, and CeO ₂ powder, which are raw material powders of YAG:Ce, was mixed with predetermined amounts of an organic binder and ethanol, and ball milling was performed in a pot. to generate a slurry. The slurry is dried, granulated, degreased and sintered to obtain YAG:Ce powder.

A predetermined amount of YAG:Ce powder obtained in the above step, MgO powder, and predetermined amounts of an organic binder and ethanol are mixed, and ball milling is performed in a pot to produce a slurry. Thereafter, the slurry is dried and granulated, and molding, degreasing, and sintering are sequentially performed to obtain the ceramic phosphor 22 of the present embodiment, which is a composite sintered body of YAG:Ce, YAG and MgO (magnesium oxide). can be obtained. The size or number of the pores 27 can be adjusted by the firing temperature, the material of the substance added to the mixture, and the like. Moreover, in order to increase the density of the sintered body, hot isostatic pressing may be applied in which sintering is performed while pressure is applied.

The dichroic layer 23 is provided on the first surface 22 a of the ceramic phosphor 22 . The dichroic layer 23 has characteristics of transmitting the excitation light E and reflecting the fluorescence Y emitted from the ceramic phosphor 22 . By providing such a dichroic layer 23, it is possible to suppress the emission of the fluorescence Y generated in the ceramic phosphor 22 to the outside.

A through hole (opening) 210 is formed in the substrate 21 of the present embodiment. A portion of the first surface 22 a of the ceramic phosphor 22 is exposed through the through hole 210 . A portion of the first surface 22 a of the ceramic phosphor 22 that is exposed through the through hole 210 is hereinafter referred to as an exposed portion 211 . In the ceramic phosphor 22 of this embodiment, the excitation light E is incident on the exposed portion 211 .

Ceramic phosphor 22 is bonded to substrate 21 via bonding member 24 . The joining member 24 of this embodiment contains a conductive filler with high thermal conductivity. At least one of metal, Al ₂ O ₃ , ZrO ₂ , MgO, and AlN is used as the material of the conductive filler contained in the joining member 24, for example. By using the joining member 24 containing the conductive filler in this way, the heat of the ceramic phosphor 22 can be efficiently transmitted to the substrate 21 side.

The substrate 21 abuts on a region of the ceramic phosphor 22 that is different from the incident region of the excitation light. Therefore, the substrate 21 also functions as a member that dissipates heat generated by the ceramic phosphor 22 . The substrate 21 is in contact with the ceramic phosphor 22 except for the through holes 210 .

Of the blue excitation light E emitted from the excitation light source 10, the ceramic phosphor 22 of the present embodiment is a part of the excitation light E emitted from the second surface 22b without being wavelength-converted. A white illumination light WL is emitted by synthesizing the light E1 and the yellow fluorescence Y generated by wavelength conversion of the excitation light E by the ceramic phosphor 22 .

The white balance of the illumination light WL emitted from the ceramic phosphor 22 is determined by the light amount ratio between the light amount of the blue light E1 and the light amount of the fluorescence Y. FIG. Hereinafter, in this specification, this light quantity ratio is referred to as the BY ratio. A condition for obtaining a practical white balance for illumination light WL used in a projector is a BY ratio of 30% to 50%.

It has been found that the BY ratio is affected by the thickness of the ceramic phosphor 22 . For example, if the thickness of the ceramic phosphor 22 is made relatively thin, the amount of blue light E1 that passes through the ceramic phosphor 22 can be increased. However, when the thickness of the ceramic phosphor 22 is less than 40 μm, it becomes difficult to manufacture the ceramic phosphor 22 . Therefore, from the viewpoint of manufacturing, it is desirable that the lower limit of the thickness of the ceramic phosphor 22 is 40 μm.

Also, if the thickness of the ceramic phosphor 22 is relatively thick, the amount of blue light E1 that passes through the ceramic phosphor 22 is reduced. Furthermore, when the thickness of the ceramic phosphor 22 exceeds 300 μm, re-absorption of the fluorescence Y in the ceramic phosphor 22 is likely to occur, so the amount of fluorescence Y that can be extracted from the second surface 22b is reduced. Therefore, from the viewpoint of the light utilization efficiency of the fluorescence Y, it is desirable that the upper limit of the thickness of the ceramic phosphor 22 is 300 μm.

Based on the above viewpoint, in the light source device 2 of the present embodiment, the thickness of the ceramic phosphor 22 is set to 40 μm or more and 300 μm or less.

Generally, in a phosphor, the width of the fluorescence emission region is wider than the width of the excitation light incidence region. This is because the excitation light incident on the phosphor is diffused and propagated over a wider area than the incident area, resulting in an increase in the width of the fluorescence emission area, that is, so-called fluorescence blurring.

Here, for example, as a comparative example, fluorescence emitted from the second surface 22b of the ceramic phosphor 22 in which both the first surface 22a and the second surface 22b are flat surfaces will be described.
In the configuration of the comparative example, if the number of pores 27 contained in the ceramic phosphor 22 is reduced, the distance between the pores 27 increases. It propagates a long distance in the phosphor and reaches the second surface 22b. Therefore, the light emission area of the light emitted from the second surface 22b is expanded.

On the other hand, if the number of pores 27 contained in the ceramic phosphor 22 is increased, the excitation light E incident on the ceramic phosphor 22 is likely to be backscattered by the pores 27 . Therefore, the excitation light E is emitted to the outside from the first surface 22a, and the conversion efficiency of the fluorescence Y by the excitation light E is lowered. Thus, in the configuration of the comparative example in which both the first surface 22a and the second surface 22b are flat surfaces, the emission area of the fluorescence Y can be suppressed by controlling the number of pores 27 included in the ceramic phosphor 22. can't.

In contrast, the ceramic phosphor 22 of the present embodiment includes a plurality of pores 27 as scattering elements that scatter the fluorescence Y, and the surface roughness of the second surface 22b that emits the fluorescence Y is reduced to that of the first surface. A structure with a rougher surface roughness than that of 22a is adopted. In this embodiment, the second surface 22b is a rough surface including fine recesses 221a, and the first surface 22a is a flat surface. The concave portion 221a of the second surface 22b is formed, for example, by polishing the second surface 22b when the ceramic phosphor 22 is manufactured.

FIG. 4 is an enlarged view showing the state of light emitted from the second surface 22b of the ceramic phosphor 22 of this embodiment. FIG. 4 shows light emitted from the second surface 22b.
As shown in FIG. 4, in the ceramic phosphor 22 of this embodiment, the fluorescence Y scattered by the pores 27 is incident on the concave portions 221a formed on the second surface 22b. The fluorescence Y incident on the recess 221 a is refracted at the interface between the recess 221 a and the air and emitted to the outside of the ceramic phosphor 22 . Part of the fluorescence incident on the portion of the second surface 22b where the concave portion 221a is not formed is totally reflected and returned into the phosphor.

In the ceramic phosphor 22 of this embodiment, the number of pores 27 is reduced to such an extent that backscattering of the excitation light E is suppressed. As the number of pores decreases, the backscattering of the excitation light E decreases. Therefore, the excitation light E is efficiently taken into the ceramic phosphor 22, and the conversion efficiency of the fluorescence Y by the excitation light E is improved.

On the other hand, when the number of pores is reduced, the above-described light scattering effect is reduced, so that the fluorescent light Y easily propagates through the phosphor, resulting in an increase in the emission area of the fluorescent light Y.
In the case of the present embodiment, since the fluorescence Y is efficiently extracted to the outside of the ceramic phosphor 22 by the concave portion 221a formed in the second surface 22b, the expansion of the emission area of the fluorescence Y is suppressed. In addition, in the case of the present embodiment, part of the blue light E1 is efficiently extracted from the ceramic phosphor 22 as the blue light E1 by the concave portion 221a, similarly to the fluorescent light Y, so that the expansion of the emission area of the blue light E1 is suppressed. be.

As described above, according to the ceramic phosphor 22 of the present embodiment, the number of pores 27 is reduced to suppress the scattering of light inside, and the recesses 221a formed in the second surface 22b improve the light extraction efficiency. It is possible to

(Effect of the first embodiment)
The light source device 2 of the present embodiment includes an excitation light source 10 that emits excitation light E, and a first surface 22a and a second surface 22b that is different from the first surface 22a. A wavelength converter having a ceramic phosphor 22 that wavelength-converts excitation light E incident on 22a to generate fluorescence Y and emits at least the fluorescence Y from a second surface 22b, and a substrate 21 that supports the ceramic phosphor 22. and a ceramic phosphor 22 containing a scattering element, the second surface 22b having a surface roughness greater than the surface roughness of the first surface 22a. In this embodiment, the scattering elements are pores 27 .

According to the light source device 2 of the present embodiment, the surface roughness of the second surface 22b becomes rougher than that of the first surface 22a due to the concave portion 221a provided on the second surface 22b that emits the fluorescence Y, so the number of pores 27 is is suppressed, the fluorescence Y can be efficiently extracted from the second surface 22b while suppressing the spread of the emission area of the fluorescence Y. Therefore, since the etendue of the fluorescence Y becomes small, the fluorescence Y is efficiently taken into the uniform illumination optical system 80 in the subsequent stage, so that the light utilization efficiency of the fluorescence Y can be improved. Similarly to the fluorescent light Y, the blue light E1 can also be efficiently extracted from the second surface 22b by the concave portion 221a.
In addition, since the backscattering of the excitation light E is suppressed by reducing the number of the pores 27, the excitation light E can be efficiently taken into the ceramic phosphor 22. FIG. Therefore, the light utilization efficiency of the excitation light E is improved, and as a result, the conversion efficiency of the fluorescence Y is improved and bright fluorescence Y can be obtained.
Therefore, according to the light source device 2 of the present embodiment, the excitation light E emitted from the excitation light source 10 can be used to efficiently generate the illumination light WL including the fluorescence Y and the blue light E1 in the ceramic phosphor 22 .

In the light source device 2 of this embodiment, the substrate 21 is made of a non-translucent material, and the ceramic phosphor 22 includes an exposed portion 211 in which a portion of the first surface 22a is exposed from the substrate 21. Light E is incident on exposed portion 211 of ceramic phosphor 22 .
In the case of this embodiment, a dichroic layer 23 is provided on the first surface 22a of the ceramic phosphor 22 to allow the excitation light E to pass therethrough and the fluorescence Y to be reflected.

According to this configuration, since the substrate 21 is made of a non-translucent member, it is possible to suppress the occurrence of loss due to leakage of the excitation light E into the substrate 21 . In addition, the excitation light E can be efficiently incident on the ceramic phosphor 22 via the exposed portion 211 .
Moreover, since the dichroic layer 23 is provided on the first surface 22a, it is possible to suppress the emission of the fluorescence Y generated in the ceramic phosphor 22 to the outside. Thereby, the fluorescence Y generated by the ceramic phosphor 22 can be efficiently extracted from the ceramic phosphor 22 .

In the light source device 2 of this embodiment, the wavelength conversion element 20 is composed of a fixed wavelength conversion element in which the incident region of the excitation light E with respect to the ceramic phosphor 22 does not change with time.

According to this configuration, it is possible to provide the fixed wavelength conversion element 20 with high light utilization efficiency.

In the light source device 2 of this embodiment, the thickness of the ceramic phosphor is 40 μm or more and 300 μm or less.

According to this configuration, by setting the thickness of the ceramic phosphor 22 to 40 μm or more and 300 μm or less, it is possible to manufacture the ceramic phosphor 22 that generates the illumination light WL with an appropriate white balance with a BY ratio of 30% to 50%. easier.

The projector 1 of this embodiment includes a light source device 2, a light modulation device that modulates light emitted from the light source device 2 according to image information to form image light, a projection optical device that projects the image light, projector with

According to the projector 1 of the present embodiment, image light is generated using the bright illumination light WL generated by the light source device 2 with high light utilization efficiency, so a high-quality image can be displayed.

(Second embodiment)
A second embodiment of the present invention will be described below with reference to FIG.
The schematic configuration of the projector of the second embodiment is the same as that of the first embodiment, and the configuration of the wavelength conversion element in the light source device is different from that of the first embodiment. Therefore, the configuration of the wavelength conversion element will be described below, and the description of other configurations will be omitted.

FIG. 5 is a cross-sectional view showing the essential configuration of the wavelength conversion element of this embodiment. As shown in FIG. 5, the wavelength conversion element 120 of this embodiment includes a substrate 121, a ceramic phosphor 122, a dichroic layer 23, and a motor 125. As shown in FIG. The wavelength conversion element 120 of this embodiment is a rotary wavelength conversion element that temporally changes the incident position of the excitation light E on the ceramic phosphor 122 .

The substrate 121 is made of a metal material such as aluminum, copper, or the like, which is excellent in heat dissipation. The substrate 121 is a rotating substrate that is rotatable around a predetermined rotation axis O. As shown in FIG. A rotation axis O passes through the center of the substrate 121 . The motor 125 rotates the disk-shaped substrate 121 around the rotation axis O. As shown in FIG.

The ceramic phosphor 122 of this embodiment is annularly formed around the rotation axis O. As shown in FIG. The ceramic phosphor 122 is configured by shaping the ceramic phosphor 22 of the first embodiment into an annular shape. Dichroic layer 23 is provided between substrate 121 and ceramic phosphor 222 . The substrate 121 dissipates heat generated by the ceramic phosphor 122 .

A dichroic layer 23 is provided on the first surface 122 a of the ceramic phosphor 122 . The annular ceramic phosphor 122 is fixed to the substrate 21 via the bonding member 24 at the radially inner end 122a1 of the first surface 122a. That is, the ceramic phosphor 122 is provided so as to protrude radially outward from the substrate 21 when viewed in plan from the direction along the rotation axis O. As shown in FIG. The excitation light E is incident on the portion of the ceramic phosphor 122 projecting radially outward from the substrate 121 . In this embodiment, the substrate 121 abuts on a region of the ceramic phosphor 122 that is different from the incident region of the excitation light E, and dissipates heat generated in the ceramic phosphor 122 .

In the wavelength conversion element 120 of this embodiment, the excitation light E is incident on the rotated ceramic phosphor 122 . When the excitation light E is incident on the ceramic phosphor 122 , heat is generated in the ceramic phosphor 122 . In this embodiment, the motor 125 rotates the ceramic phosphor 122 to temporally move the incident position of the excitation light E on the ceramic phosphor 122 . As a result, the same position of the ceramic phosphor 122 is always irradiated with the excitation light E, so that only a part of the ceramic phosphor 122 is locally heated, and deterioration of the ceramic phosphor 122 is suppressed.

In the case of this embodiment, heat dissipation can be further improved by rotating the ceramic phosphor 122 .

Also in the wavelength conversion element 120 of this embodiment, the substrate 121 in contact with the ceramic phosphor 122 is made of a non-translucent member. As a result, in the wavelength conversion element 120 , the fluorescence Y generated by the ceramic phosphor 122 is efficiently extracted to the outside without leaking out to the substrate 121 .

(Effect of Second Embodiment)
Similar to the wavelength conversion element 20 of the above-described embodiment, the wavelength conversion element 120 of this embodiment can efficiently generate the illumination light WL including the fluorescence Y and the blue light E1 in the ceramic phosphor 122 and output it to the outside. Further, the wavelength conversion element 120 of this embodiment is a rotary wavelength conversion device that temporally changes the incident region of the excitation light E with respect to the ceramic phosphor 22 by rotating the substrate 121 around the predetermined rotation axis O. It consists of elements.

According to the light source device including the wavelength conversion element 120 of the present embodiment, the illumination light WL can be efficiently used when the rotary wavelength conversion element 120 is used. In addition, by improving the heat dissipation property of the ceramic phosphor 122, it is possible to suppress a decrease in the amount of fluorescence due to a decrease in the wavelength conversion efficiency of the ceramic phosphor 122. FIG. Therefore, by using this light source device, it is possible to reduce the etendue and to provide a projector capable of displaying high-quality images, which is the same effect as in the first embodiment.

The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

(Modification)
Although the transmission-type wavelength conversion element is exemplified in the above embodiment, the present invention is not limited to this.
The configuration of the wavelength conversion element according to the modification will be described below with reference to FIG.
FIG. 6 is a cross-sectional view showing the essential configuration of a wavelength conversion element of a modification. As shown in FIG. 6, in the wavelength conversion element 220 of the present modified example, the ceramic phosphor 222 includes a first surface 222a, a second surface 222b, a third surface 222c, and reflectors provided on the third surface 222c. It includes a membrane 28 and a plurality of pores 27 . The third surface 222c is a surface different from the first surface 222a and the second surface 222b. The reflective film 28 is composed of, for example, a metal mirror or a dielectric multilayer film. The ceramic phosphor 222 has a fourth surface 222d facing opposite to the second surface 222b supported by a substrate (not shown).

In the ceramic phosphor 222 of this modified example, the first surface 222a is the surface on which the excitation light E is incident, and the second surface 222b is the surface from which the illumination light WL is emitted. The third surface 222c is provided with the reflecting film 28 to reflect the excitation light E and the fluorescence Y toward the second surface 222b. Also in this modification, the surface roughness of the second surface 222b is rougher than the surface roughness of the first surface 22a. The second surface 222b is a rough surface including fine recesses 221a, and the first surface 222a is a flat surface.

The ceramic phosphor 222 of this modified example converts the wavelength of the excitation light E incident from the first surface 222a to generate fluorescence Y, and reflects part of the excitation light E and the fluorescence Y from the third surface 222c. , and emits the illumination light WL from the second surface 222b. As in the first embodiment, the first surface 222a may be provided with a dichroic layer as an optical layer that transmits excitation light and reflects fluorescence.

According to the ceramic phosphor 222 of this modified example, as in the above-described embodiment, the illumination light WL generated using the excitation light E incident from the first surface 222a is efficiently emitted from the second surface 222b. A wavelength conversion element is provided.

Further, for example, in the above-described embodiments, the substrates 21 and 121 are entirely made of a non-translucent member (metal). Leakage of the fluorescent light Y can be prevented if the part that contacts with the lens is made of a non-translucent member. Therefore, the substrates 21 and 121 may be made of a translucent member except for the portion that abuts on one of the ceramic phosphors 22 and 122 .

Further, for example, in the ceramic phosphors 22 and 122 of the above embodiments, the phosphor phase 25 contains an oxide phosphor, and the matrix phase 26 contains a metal oxide. Alternatively, the phosphor phase 25 may contain nitride phosphors and the matrix phase 26 may contain metal nitrides. SiAlON phosphors such as α-SiAlON and β-SiAlON can be used as nitride phosphors. AlN, for example, can be used as the metal nitride. AlN has a thermal conductivity of about 255 W/m·K. In this way, when the phosphor phase 25 contains a nitride phosphor and the matrix phase 26 contains a metal oxide, it is possible to stably produce a ceramic phosphor without causing unnecessary oxidation reaction or the like in each phase. can be done.

In addition, specific descriptions of the shape, number, arrangement, material, manufacturing method, etc. of each component of the ceramic phosphor, the wavelength conversion element, the light source device, and the projector are not limited to the above embodiments, and can be changed as appropriate. be. In the above embodiment, an example in which the light source device according to the present invention is installed in a projector using a liquid crystal light valve has been described, but the present invention is not limited to this. For example, the light source device according to the present invention may be installed in a projector using a digital micromirror device as an optical modulator.

In the above embodiment, an example in which the light source device according to the present invention is installed in the projector has been shown, but the present invention is not limited to this. The light source device according to the present invention can also be applied to lighting fixtures, automobile headlights, and the like.

A light source device according to an aspect of the present invention may have the following configuration.
A light source device according to one aspect of the present invention includes an excitation light source that emits excitation light, a first surface, and a second surface that is different from the first surface. a wavelength conversion element having a ceramic phosphor for wavelength-converting excitation light to generate fluorescence and emitting at least the fluorescence from a second surface; and a substrate supporting the ceramic phosphor, wherein the ceramic phosphor scatters element, and the surface roughness of the second surface is greater than the surface roughness of the first surface.

In one aspect of the light source device of the present invention, the scattering elements may be pores.

In one aspect of the light source device of the present invention, the substrate is made of a non-translucent material, the ceramic phosphor includes an exposed portion in which a portion of the first surface is exposed from the substrate, and the excitation light is It may be configured to be incident on the exposed portion of the ceramic phosphor.

The light source device according to one aspect of the present invention may further include an optical layer provided on the first surface of the ceramic phosphor to transmit excitation light and reflect fluorescence.

In one aspect of the light source device of the present invention, the wavelength conversion element may be a fixed wavelength conversion element in which the incident region of the excitation light with respect to the ceramic phosphor does not change with time.

In the light source device according to one aspect of the present invention, the wavelength conversion element is a rotary wavelength conversion element that temporally changes the incident region of the excitation light to the ceramic phosphor by rotating the substrate around a predetermined rotation axis. It is good also as a structure which is an element.

In one aspect of the light source device of the present invention, the ceramic phosphor includes a third surface different from the first surface and the second surface, and a reflective film provided on the third surface. A configuration in which light is emitted from the second surface may be employed.

In one aspect of the light source device of the present invention, the thickness of the ceramic phosphor may be 40 μm or more and 300 μm or less.

A projector according to one aspect of the present invention may have the following configuration.
A projector according to one aspect of the present invention includes a light source device according to the above aspect of the present invention, an optical modulation device that modulates light emitted from the light source device according to image information to form image light, and projects image light. and a projection optical device for

DESCRIPTION OF SYMBOLS 1... Projector, 2... Light source device, 4B, 4G, 4R... Light modulation device, 6... Projection optical device, 10... Excitation light source, 20, 120, 220... Wavelength conversion element, 21, 121... Substrate, 21a... Surface, 22, 122, 222... ceramic phosphor, 22a, 122a, 222a... first surface, 22b, 222b... second surface, 23... dichroic layer (optical layer), 27... pore (scattering element), 28... reflective film, 211... Exposed portion, 222c... Third surface, E... Excitation light, O... Rotation axis, Y... Fluorescence.

Claims (9)

an excitation light source that emits excitation light;
including a first surface and a second surface different from the first surface, wavelength-converting the excitation light irradiated from the excitation light source and incident on the first surface to generate fluorescence, and the second surface a wavelength conversion element having a ceramic phosphor that emits at least the fluorescence from and a substrate that supports the ceramic phosphor,
the ceramic phosphor includes a scattering element;
A light source device in which the surface roughness of the second surface is rougher than the surface roughness of the first surface. The light source device according to claim 1, wherein the scattering elements are pores. The substrate is made of a non-translucent material,
The ceramic phosphor includes an exposed portion in which a portion of the first surface is exposed from the substrate,
The light source device according to claim 1 or 2, wherein the excitation light enters the exposed portion of the ceramic phosphor. The light source device according to claim 3, further comprising an optical layer provided on the first surface of the ceramic phosphor, transmitting the excitation light and reflecting the fluorescence. The light source device according to any one of claims 1 to 4, wherein the wavelength conversion element is a fixed type wavelength conversion element in which an incident region of the excitation light with respect to the ceramic phosphor does not change with time. . 2. The wavelength conversion element is a rotary wavelength conversion element that temporally changes the incident region of the excitation light with respect to the ceramic phosphor by rotating the substrate around a predetermined rotation axis. The light source device according to claim 4 . The ceramic phosphor includes a third surface different from the first surface and the second surface, and a reflective film provided on the third surface,
The light source device according to any one of claims 1 to 4, wherein light reflected by the reflective film is emitted from the second surface. The light source device according to any one of claims 1 to 7, wherein the ceramic phosphor has a thickness of 40 µm or more and 300 µm or less. A light source device according to any one of claims 1 to 8;
a light modulating device that modulates light emitted from the light source device according to image information to form image light;
and a projection optical device that projects the image light.

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