Light source device and projector

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

Technical Field

[0001] The present invention relates to a light source device and a projector.

Background Art

[0002] Conventionally, a light source device that uses fluorescence emitted from a phosphor when the phosphor is irradiated with excitation light emitted from a light source has been proposed. Patent Document 1 below discloses a reflective phosphor unit that emits fluorescence from the surface on which the excitation light is incident. Patent Document 2 below discloses a transmissive phosphor unit that emits fluorescence from the surface opposite to the surface on which the excitation light is incident.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the phosphor unit of Patent Document 1 above, since the light emitting surface of the phosphor is formed as a uniform plane, when the light is emitted from the light emitting surface, the light is refracted and the light emitting area is enlarged, so that it cannot be efficiently taken into the subsequent optical system and the light utilization efficiency is reduced. Further, in the phosphor unit of Patent Document 2 above, since the excitation light enters the phosphor through the transparent substrate, a part of the excitation light reflected at the interface between the phosphor and the transparent substrate becomes stray light in the transparent substrate and the light utilization efficiency is reduced.

Means for Solving the Problems

[0005] To solve the above problems, a light source device according to an aspect of the present invention includes an excitation light source that irradiates excitation light, a ceramic phosphor that wavelength-converts a part of the excitation light irradiated from the excitation light source and incident on a first surface to generate fluorescence, and emits at least the fluorescence 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 the surface roughness of the first surface is rougher than the surface roughness of the second surface.

[0006] A projector according to an aspect of the present invention includes the above light source device, a light modulation device that modulates the 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.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the drawings used in the following description may show the characteristic parts enlarged for the sake of easy understanding of the characteristics, and the dimensional ratios of the respective components are not necessarily the same as the actual ones.

[0009] (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 a light source device. As shown in FIG. 1, the projector 1 of the present 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, light modulation devices 4R, 4G, and 4B, a combining optical system 5, and a projection optical device 6.

[0010] 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 relay lens 9a and a second relay lens 9b.

[0011] The first dichroic mirror 7a separates the illumination light WL from the light source device 2 into red light LR and other light (green light LG and blue light LB). The first dichroic mirror 7a transmits the red light LR and reflects the other light (green light LG and blue light LB). On the other hand, the second dichroic mirror 7b separates the other light (green light LG and blue light LB) into green light LG and blue light LB by reflecting the green light LG and transmitting the blue light LB.

[0012] The first total reflection mirror 8a is disposed 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 modulation device 4R. On the other hand, the second total reflection mirror 8b and the third total reflection mirror 8c are disposed 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 modulation device 4B. The green light LG is reflected from the second dichroic mirror 7b toward the light modulation device 4G.

[0013] The first relay lens 9a and the second relay lens 9b are arranged on the light emission 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 a function of compensating for the light 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.

[0014] The light modulation device 4R modulates the red light LR according to the image information and forms image light corresponding to the red light LR. The light modulation device 4G modulates the green light LG according to the image information and forms image light corresponding to the green light LG. The light modulation device 4B modulates the blue light LB according to the image information and forms image light corresponding to the blue light LB.

[0015] For example, transmissive liquid crystal panels are used for the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B. In addition, polarizing plates (not shown) are arranged on each of the incident side and the emission side of the liquid crystal panel.

[0016] In addition, field lenses 10R, 10G, and 10B are arranged on the incident sides of the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B, respectively. The field lenses 10R, 10G, and 10B collimate the red light LR, the green light LG, and the blue light LB incident on the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B, respectively.

[0017] Image light from the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B is incident on the combining optical system 5. The combining optical system 5 combines the image lights corresponding to the red light LR, the green light LG, and the blue light LB, respectively, and emits the combined image light toward the projection optical device 6. For example, a cross dichroic prism is used for the combining optical system 5.

[0018] The projection optical device 6 is composed of a projection lens group and enlarges and projects the image light combined by the combining optical system 5 toward the screen SCR. As a result, an enlarged video is displayed on the screen SCR.

[0019] (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 illumination optical system 80.

[0020] The excitation light source 10 includes a plurality of semiconductor lasers 10a that emit blue excitation light E composed of laser light, and a plurality of collimator lenses 10b. The plurality of semiconductor lasers 10a are arranged in an array in a plane orthogonal to the illumination optical axis 100ax. The collimator lenses 10b are arranged in an array in a plane orthogonal 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.

[0021] The afocal optical system 11 includes, for example, a convex lens 11a and a concave lens 11b. The afocal optical system 11 reduces the beam diameter of the excitation light E composed of a parallel light beam emitted from the excitation light source 10.

[0022] The homogenizer optical system 12 includes, for example, a first multi-lens array 12a and a second multi-lens array 12b. The homogenizer optical system 12 makes the light intensity distribution of the excitation light into a uniform state, a so-called top-hat distribution, on the wavelength conversion element 20 described later. The homogenizer optical system 12 superimposes a plurality of small light beams emitted from the plurality of lenses of the first multi-lens array 12a and the second multi-lens array 12b on the wavelength conversion element 20 together with the condensing optical system 13. Thereby, the light intensity distribution of the excitation light E irradiated on the wavelength conversion element 20 is made uniform.

[0023] The light collecting optical system 13 includes, for example, a first lens 13a and a second lens 13b. In the present embodiment, the first lens 13a and the second lens 13b are each composed of a convex lens. The light collecting optical system 13 is disposed in the optical path from the homogenizer optical system 12 to the wavelength conversion element 20, and collects the excitation light E and makes it incident on the wavelength conversion element 20. The configuration of the wavelength conversion element 20 will be described later.

[0024] The pickup optical system 30 includes, for example, a first collimating lens 31 and a second collimating lens 32. The pickup optical system 30 is a collimating optical system that substantially collimates 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 is incident on the uniform illumination optical system 80.

[0025] The uniform illumination optical system 80 includes a first lens array 81, a second lens array 82, a polarization conversion element 83, and a superposition lens 84.

[0026] The first lens array 81 has a plurality of first lenses 81a for dividing the illumination light WL from the light source device 2 into a plurality of partial light beams. The plurality of first lenses 81a are arranged in a matrix in a plane orthogonal to the illumination optical axis 100ax.

[0027] The second lens array 82 has a plurality of second lenses 82a corresponding to the plurality of first lenses 81a of the first lens array 81. The plurality of second lenses 82a are arranged in a matrix in a plane orthogonal to the illumination optical axis 100ax.

[0028] The second lens array 82, together with the superposition lens 84, forms an image of each first lens 81a of the first lens array 81 in the vicinity of the image formation regions of the optical modulation device 4R, the optical modulation device 4G, and the optical modulation device 4B, respectively.

[0029] 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).

[0030] The superimposing lens 84 condenses each partial light beam emitted from the polarization conversion element 83 and superimposes them in the vicinity of the image formation regions of the light modulation devices 4R, 4G, and 4B, respectively.

[0031] (Wavelength conversion element) Next, the configuration of the wavelength conversion element 20 will be described. FIG. 3 is a cross-sectional view showing the main part configuration of the wavelength conversion element 20. Note that FIG. 3 corresponds to a cross-section obtained by cutting the wavelength conversion element 20 in a plane including the illumination optical axis 100ax of FIG. 2.

[0032] As shown in FIG. 3, the wavelength conversion element 20 of the present 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 the present embodiment is a fixed type wavelength conversion element that does not temporally change the incident position of the excitation light E on the ceramic phosphor 22.

[0033] The substrate 21 is made of a metal material having excellent heat dissipation properties such as aluminum or copper, for example. The substrate 21 is a support member that supports the ceramic phosphor 22. The substrate 21 of the present embodiment is made of a non-translucent member. The substrate 21 is made of a metal material having excellent heat dissipation properties such as aluminum or copper, for example. The substrate 21 of the present embodiment has a higher thermal conductivity than the ceramic phosphor 22. The substrate 21 has surfaces (one surface) 21a and a back surface facing in opposite directions. The surface 21a of the substrate 21 is a surface that supports the ceramic phosphor 22.

[0034] 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 conversion element that wavelength-converts a 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.

[0035] The ceramic phosphor 22 includes a phosphor phase 25, a matrix phase 26, and a plurality of pores (scattering elements) 27. The phosphor phase 25 contains an oxide phosphor to which an activator is added. The phosphor phase 25 contains, for example, yttrium aluminum garnet (YAG(Y3Al5O 12 ):Ce) to which cerium (Ce) is added as an activator.

[0036] Taking YAG:Ce as an example, as phosphor particles, materials obtained by mixing raw material powders containing constituent elements such as Y2O3, Al2O3, and CeO3 and subjecting them to a solid-phase reaction, Y-Al-O amorphous particles obtained by a wet method such as a coprecipitation method or a sol-gel method, and YAG particles obtained by a gas-phase method such as a spray drying method, a flame pyrolysis method, or a thermal plasma method can be used.

[0037] The oxide phosphor constituting the phosphor phase 25 is Y3Al5O 12 In addition to this, it may contain at least one of Y3(Al,Ga)5O 12 , Lu3Al5O 12 , TbAl5O 12 The phosphor phase 25 may contain europium (Eu) instead of cerium (Ce) as an activator.

[0038] The matrix phase 26 functions as a binder that binds together a plurality of phosphor particles constituting the phosphor phase 25. The matrix phase 26 is composed of a material containing MgO (magnesium oxide) as a translucent ceramic. The thermal conductivity of the magnesium oxide constituting the matrix phase 26 is about 50 W / m·K, and the thermal conductivity of the YAG constituting the phosphor phase 25 is about 12 W / m·K. In the present embodiment, the matrix phase 26 contains a translucent ceramic having a higher thermal conductivity than the phosphor phase 25.

[0039] The metal oxide constituting the matrix phase 26 may contain at least one of Al2O3, ZnO, TiO2, Y2O3, YAlO3, BeO, and MgAl2O4 in addition to the above-mentioned MgO.

[0040] The thermal conductivity of Al2O3 is about 30 W / m·K, the thermal conductivity of ZnO is about 25 W / m·K, the thermal conductivity of TiO2 is about 43 W / m·K, the thermal conductivity of Y2O3 is about 27 W / m·K, the thermal conductivity of YAlO3 is about 12 W / m·K, the thermal conductivity of BeO is about 250 W / m·K, and the thermal conductivity of MgAl2O4 is about 14 W / m·K.

[0041] The plurality of pores 27 are scattering elements for scattering the excitation light E and the fluorescence Y. The average diameter of the plurality of pores 27 is set to, for example, about 1 μm or less. Note that the scattering element is 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.

[0042] Such a ceramic phosphor 22 can be manufactured, for example, by the following steps. A predetermined amount of Al2O3 powder, Y2O3 powder, and CeO2 powder, which are raw material powders of YAG:Ce, are mixed with a predetermined amount of an organic binder and ethanol, and ball milling is performed in a pot to generate a slurry. The slurry is dried, defatted, and sintered after granulation to obtain YAG:Ce powder.

[0043] A predetermined amount of YAG:Ce powder obtained in the above process, MgO powder, a predetermined amount of organic binder, and ethanol are mixed, and ball milling is performed in a pot to generate a slurry. Then, the slurry is dried and granulated, and molding, debinding, and sintering are sequentially performed to obtain the ceramic phosphor 22 of the present embodiment composed of a composite sintered body of YAG:Ce, YAG, and MgO (magnesium oxide). Note that 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. Further, in order to increase the density of the sintered body, hot isostatic pressing may be applied in which sintering is performed under pressure.

[0044] The dichroic layer 23 is provided on the first surface 22a of the ceramic phosphor 22. The dichroic layer 23 has the property 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 fluorescence Y generated in the ceramic phosphor 22 from being emitted to the outside.

[0045] A through hole (opening) 210 is formed in the substrate 21 of the present embodiment. A part of the first surface 22a of the ceramic phosphor 22 is exposed through the through hole 210. Hereinafter, in the ceramic phosphor 22, the portion of the first surface 22a that is exposed through the through hole 210 is referred to as an exposed portion 211. In the ceramic phosphor 22 of the present embodiment, the excitation light E is incident on the exposed portion 211.

[0046] The ceramic phosphor 22 is joined to the substrate 21 via a joining member 24. The joining member 24 of the present embodiment contains a conductive filler having a high thermal conductivity. As the material of the conductive filler contained in the joining member 24, for example, at least one of metal, Al2O3, ZrO2, MgO, and AlN is used. By using the joining member 24 containing such a conductive filler, the heat of the ceramic phosphor 22 can be efficiently transmitted to the substrate 21 side.

[0047] The substrate 21 abuts on a region different from the excitation light incident region in the ceramic phosphor 22. Therefore, the substrate 21 also functions as a member for dissipating the heat generated in the ceramic phosphor 22. The substrate 21 abuts on the ceramic phosphor 22 at a portion excluding the through hole 210.

[0048] The ceramic phosphor 22 of the present embodiment emits white illumination light WL synthesized from blue light (transmitted light) E1, which is a part of the excitation light E emitted from the excitation light source 10 and is emitted from the second surface 22b without being wavelength-converted, and yellow fluorescence Y generated by wavelength conversion of the excitation light E by the ceramic phosphor 22.

[0049] The white balance of the illumination light WL emitted from the ceramic phosphor 22 is determined by the light quantity ratio between the light quantity of the blue light E1 and the light quantity of the fluorescence Y. Hereinafter, in this specification, this light quantity ratio is referred to as the BY ratio. The condition for obtaining a practical white balance as the illumination light WL used in the projector is that the BY ratio is 30% to 50%.

[0050] It has been found that the BY ratio is affected by the thickness of the ceramic phosphor 22. For example, when the thickness of the ceramic phosphor 22 is relatively decreased, the light quantity of the blue light E1 transmitted through the ceramic phosphor 22 can be increased. However, when the thickness of the ceramic phosphor 22 becomes thinner 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 value of the thickness of the ceramic phosphor 22 is 40 μm.

[0051] On the other hand, when the thickness of the ceramic phosphor 22 is relatively increased, the light quantity of the blue light E1 transmitted through the ceramic phosphor 22 decreases. Furthermore, when the thickness of the ceramic phosphor 22 exceeds 300 μm, reabsorption of the fluorescence Y easily occurs in the ceramic phosphor 22, so that the light quantity of the fluorescence Y that can be extracted from the second surface 22b decreases. Therefore, from the viewpoint of the light utilization efficiency of the fluorescence Y, it is desirable that the upper limit value of the thickness of the ceramic phosphor 22 is 300 μm.

[0052] Based on the above viewpoints, in the light source device 2 of the present embodiment, the thickness of the ceramic phosphor 22 is set to be 40 μm or more and 300 μm or less.

[0053] Generally, in a phosphor, the width of the fluorescence emission region is wider than the width of the excitation light incident region. This is due to the so-called fluorescence bleeding, where the excitation light incident on the phosphor is scattered and propagates in a region wider than the incident region, causing the width of the fluorescence emission region to expand.

[0054] Here, for example, as a comparative example, the 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, when the number of pores 27 contained in the ceramic phosphor 22 is reduced, the distance between the pores 27 increases. Therefore, the light scattered by a certain pore 27 propagates a long distance within the phosphor before being scattered by another pore 27 and reaches the second surface 22b. As a result, the emission area of the light emitted from the second surface 22b is in an enlarged state.

[0055] On the other hand, when the number of pores 27 contained in the ceramic phosphor 22 is increased, the excitation light E incident on the ceramic phosphor 22 is easily 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 decreases. Thus, in the configuration of the comparative example in which both the first surface 22a and the second surface 22b are flat surfaces, it is not possible to suppress the emission area of the fluorescence Y by controlling the number of pores 27 contained in the ceramic phosphor 22.

[0056] In contrast, the ceramic phosphor 22 of the present embodiment adopts a configuration in which while including a plurality of pores 27 as scattering elements for scattering the fluorescence Y, the surface roughness of the second surface 22b that emits the fluorescence Y is made rougher than the surface roughness of the first surface 22a. In the present embodiment, the second surface 22b is configured as a rough surface including fine recesses 221a, and the first surface 22a is configured as a flat surface. The recesses 221a on the second surface 22b are formed, for example, by a process of polishing the second surface 22b during the manufacture of the ceramic phosphor 22.

[0057] FIG. 4 is an enlarged view of the main part showing the state of the light emitted from the second surface 22b of the ceramic phosphor 22 of the present embodiment. In FIG. 4, the light emitted from the second surface 22b is shown. As shown in FIG. 4, in the ceramic phosphor 22 of the present embodiment, the fluorescent Y scattered by the pores 27 enters the recess 221a formed in the second surface 22b. The fluorescent Y that has entered the recess 221a is refracted at the interface between the recess 221a and the air and is emitted to the outside of the ceramic phosphor 22. Note that a part of the fluorescence that has entered the portion of the second surface 22b where the recess 221a is not formed is totally reflected and returned into the phosphor.

[0058] In the ceramic phosphor 22 of the present embodiment, the number of pores 27 is reduced to such an extent that the backscattering of the excitation light E is suppressed. When the number of pores decreases, the backscattering of the excitation light E decreases. Therefore, since the excitation light E is efficiently taken into the ceramic phosphor 22, the conversion efficiency of the fluorescent Y by the excitation light E is improved.

[0059] On the other hand, when the number of pores decreases, the scattering effect of the light described above decreases, so that the fluorescent Y easily propagates through the phosphor, and thus the emission area of the fluorescent Y expands. In the case of the present embodiment, since the recess 221a formed in the second surface 22b efficiently extracts the fluorescent Y to the outside of the ceramic phosphor 22, the expansion of the emission area of the fluorescent Y is suppressed. Also, in the case of the present embodiment, a part of the blue light E1 is efficiently extracted from the ceramic phosphor 22 as the blue light E1 by the recess 221a, similarly to the fluorescent Y, so that the expansion of the emission area of the blue light E1 is suppressed.

[0060] As described above, according to the ceramic phosphor 22 of the present embodiment, it is possible to suppress the scattering of light inside by reducing the number of pores 27 and improve the light extraction efficiency by the recess 221a formed in the second surface 22b.

[0061] (Effect of the First Embodiment) The light source device 2 of the present embodiment includes an excitation light source 10 that irradiates excitation light E, a first surface 22a, and a second surface 22b different from the first surface 22a. The excitation light E irradiated from the excitation light source 10 and incident on the first surface 22a is wavelength-converted to generate fluorescence Y, and a ceramic phosphor 22 that emits at least the fluorescence Y from the second surface 22b, and a substrate 21 that supports the ceramic phosphor 22. The wavelength conversion element 20 has a ceramic phosphor 22 that includes scattering elements, and the surface roughness of the second surface 22b is rougher than the surface roughness of the first surface 22a. In the case of the present embodiment, the scattering element is a pore 27.

[0062] According to the light source device 2 of the present embodiment, since the surface roughness of the second surface 22b is rougher than that of the first surface 22a due to the recess 221a provided on the second surface 22b that emits the fluorescence Y, even when the number of pores 27 is suppressed, the fluorescence Y can be efficiently extracted from the second surface 22b while suppressing the spread of the light emission area of the fluorescence Y. Therefore, since the étendue of the fluorescence Y becomes small, the light utilization efficiency of the fluorescence Y can be improved by efficiently taking in the fluorescence Y into the subsequent uniform illumination optical system 80. Also, for the blue light E1, similar to the fluorescence Y, it can be efficiently extracted from the second surface 22b by the recess 221a. Further, by reducing the number of pores 27, the backward scattering of the excitation light E is suppressed, so that the excitation light E can be efficiently taken into the ceramic phosphor 22. Therefore, the light utilization efficiency of the excitation light E is improved, and as a result, the conversion efficiency of the fluorescence Y can be improved to obtain bright fluorescence Y. Therefore, according to the light source device 2 of the present embodiment, the illumination light WL including the fluorescence Y and the blue light E1 can be efficiently generated in the ceramic phosphor 22 using the excitation light E emitted from the excitation light source 10.

[0063] In the light source device 2 of the present embodiment, the substrate 21 is made of a non-translucent material, the ceramic phosphor 22 includes an exposed portion 211 where a part of the first surface 22a is exposed from the substrate 21, and the excitation light E is incident on the exposed portion 211 of the ceramic phosphor 22. In the case of this embodiment, a dichroic layer 23 is further provided on the first surface 22a of the ceramic phosphor 22, which transmits the excitation light E and reflects the fluorescence Y.

[0064] According to this configuration, since the substrate 21 is composed of a non-translucent member, it is possible to suppress the occurrence of loss due to the 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 through the exposed portion 211. Moreover, since the dichroic layer 23 is provided on the first surface 22a, it is possible to suppress the fluorescence Y generated in the ceramic phosphor 22 from being emitted to the outside. As a result, the fluorescence Y generated by the ceramic phosphor 22 can be efficiently extracted from the ceramic phosphor 22.

[0065] In the light source device 2 of this embodiment, the wavelength conversion element 20 is composed of a fixed-type 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.

[0066] According to this configuration, it is possible to provide the fixed-type wavelength conversion element 20 with high light utilization efficiency.

[0067] 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.

[0068] According to this configuration, by setting the thickness of the ceramic phosphor 22 to 40 μm or more and 300 μm or less, it becomes easy to manufacture the ceramic phosphor 22 that generates illumination light WL with an appropriate white balance having a BY ratio of 30% to 50%.

[0069] The projector 1 of this embodiment is a projector including a light source device 2, a light modulation device that modulates the light emitted from the light source device 2 according to image information to form image light, and a projection optical device that projects the image light.

[0070] According to the projector 1 of the present embodiment, since the image light is generated using the bright illumination light WL generated by the light source device 2 with high light utilization efficiency, a high-quality image can be displayed.

[0071] (Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to FIG. 5. The schematic configuration of the projector in the second embodiment is the same as that in the first embodiment, and the configuration of the wavelength conversion element in the light source device is different from that in the first embodiment. Therefore, hereinafter, the configuration of the wavelength conversion element will be described, and the description of other configurations will be omitted.

[0072] FIG. 5 is a cross-sectional view showing a main part configuration of the wavelength conversion element of the present embodiment. As shown in FIG. 5, the wavelength conversion element 120 of the present embodiment includes a substrate 121, a ceramic phosphor 122, a dichroic layer 23, and a motor 125. The wavelength conversion element 120 of the present embodiment is a rotary type wavelength conversion element that temporally changes the incident position of the excitation light E on the ceramic phosphor 122.

[0073] The substrate 121 is made of a metal material having excellent heat dissipation properties such as aluminum and copper. The substrate 121 is a rotary substrate that can rotate around a predetermined rotation axis O. The 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.

[0074] The ceramic phosphor 122 of the present embodiment is formed in an annular shape around the rotation axis O. The ceramic phosphor 122 is formed by shaping the ceramic phosphor 22 of the first embodiment into an annular shape. The dichroic layer 23 is provided between the substrate 121 and the ceramic phosphor 222. The substrate 121 dissipates the heat generated by the ceramic phosphor 122.

[0075] A dichroic layer 23 is provided on the first surface 122a of the ceramic phosphor 122. The annular ceramic phosphor 122 has the radially inner end portion 122a1 of the first surface 122a fixed to the substrate 21 via a joining member 24. That is, when viewed in plan from the direction along the rotation axis O, the ceramic phosphor 122 is provided so as to protrude radially outward from the substrate 21. The excitation light E is incident on the portion of the ceramic phosphor 122 that protrudes radially outward of the substrate 121. In the present embodiment, the substrate 121 abuts on a region different from the incident region of the excitation light E in the ceramic phosphor 122 and dissipates the heat generated in the ceramic phosphor 122.

[0076] In the wavelength conversion element 120 of the present embodiment, the excitation light E is incident on the rotating ceramic phosphor 122. When the excitation light E is incident on the ceramic phosphor 122, heat is generated in the ceramic phosphor 122. In the present embodiment, the ceramic phosphor 122 is rotated by the motor 125, so that the incident position of the excitation light E in the ceramic phosphor 122 is temporally moved. As a result, the excitation light E is constantly irradiated on the same position of the ceramic phosphor 122, so that only a part of the ceramic phosphor 122 is locally heated, and deterioration of the ceramic phosphor 122 is suppressed.

[0077] In the case of the present embodiment, the heat dissipation property can be further enhanced by rotating the ceramic phosphor 122.

[0078] Also in the wavelength conversion element 120 of the present embodiment, the substrate 121 in contact with the ceramic phosphor 122 is made of a non-translucent member. Thereby, in the wavelength conversion element 120, the fluorescence Y generated in the ceramic phosphor 122 is efficiently taken out to the outside without leaking out to the substrate 121.

[0079] (Effect of the Second Embodiment) The wavelength conversion element 120 of the present embodiment is similar to the wavelength conversion element 20 of the above embodiment, and can efficiently generate illumination light WL including fluorescence Y and blue light E1 in the ceramic phosphor 122 and extract it to the outside. Further, the wavelength conversion element 120 of the present embodiment is a rotation type wavelength conversion element that changes the incident region of the excitation light E with respect to the ceramic phosphor 22 over time by rotating the substrate 121 around a predetermined rotation axis O.

[0080] According to the light source device including the wavelength conversion element 120 of the present embodiment, when the rotation type wavelength conversion element 120 is used, the illumination light WL can be efficiently utilized. Further, 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. Therefore, by using this light source device, the same effects as those of the first embodiment, such as reducing the étendue and providing a projector capable of displaying a high-quality image, can be obtained.

[0081] Note that the technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0082] (Modification example) In the above embodiment, a transmissive wavelength conversion element is taken as an example, but the present invention is not limited to this. Hereinafter, the configuration of the wavelength conversion element according to the modification example will be described with reference to FIG. 6. FIG. 6 is a cross-sectional view showing the main configuration of the wavelength conversion element of the modification example. As shown in FIG. 6, in the wavelength conversion element 220 of the present modification example, the ceramic phosphor 222 includes a first surface 222a, a second surface 222b, a third surface 222c, a reflective film 28 provided on the third surface 222c, 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 is supported by a substrate (not shown) with a fourth surface 222d facing the opposite side of the second surface 222b.

[0083] In the ceramic phosphor 222 of this modification 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 the surface on which the reflective film 28 is provided, and reflects 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 that of the first surface 22a. The second surface 222b is composed of a rough surface including fine recesses 221a, and the first surface 222a is composed of a flat surface.

[0084] The ceramic phosphor 222 of this modification example is a reflective wavelength conversion element that wavelength-converts the excitation light E incident from the first surface 222a to generate fluorescence Y, and reflects a part of the excitation light E and the fluorescence Y at the third surface 222c to emit the illumination light WL from the second surface 222b. Note that, as in the first embodiment, a dichroic layer may be provided on the first surface 222a as an optical layer that transmits the excitation light and reflects the fluorescence.

[0085] According to the ceramic phosphor 222 of this modification example, as in the above embodiment, a reflective wavelength conversion element is provided that efficiently emits the illumination light WL generated using the excitation light E incident from the first surface 222a from the second surface 222b.

[0086] Further, for example, in the above embodiment, the case where the entire substrate 21, 121 is made of a non-translucent member (metal) is taken as an example. However, if at least the portion of the substrate 21, 121 that abuts on any of the ceramic phosphors 22, 122 is made of a non-translucent member, light leakage of the fluorescence Y can be prevented. Therefore, the substrate 21, 121 may be made of a translucent member except for the portion that abuts on any of the ceramic phosphors 22, 122.

[0087] Further, for example, in the ceramic phosphors 22, 122 of the above embodiment, the phosphor phase 25 included an oxide phosphor and the matrix phase 26 included a metal oxide. Instead of this configuration, the phosphor phase 25 may include a nitride phosphor and the matrix phase 26 may include a metal nitride. As the nitride phosphor, for example, sialon phosphors such as α-SiAlON and β-SiAlON can be used. As the metal nitride, for example, AlN or the like can be used. The thermal conductivity of AlN is about 255 W / m·K. Thus, when the phosphor phase 25 includes a nitride phosphor and the matrix phase 26 includes a metal oxide, the ceramic phosphor can be stably manufactured without causing unnecessary oxidation reactions or the like in each phase.

[0088] In addition, specific descriptions of the shape, number, arrangement, material, manufacturing method, etc. of each component of the ceramic phosphor, wavelength conversion element, light source device, and projector are not limited to the above embodiment and can be appropriately changed. In the above embodiment, an example in which the light source device according to the present invention is mounted on a projector using a liquid crystal light valve has been shown, but the present invention is not limited thereto. For example, the light source device according to the present invention may be mounted on a projector using a digital micromirror device as a light modulation device.

[0089] In the above embodiment, an example in which the light source device according to the present invention is mounted on a projector has been shown, but the present invention is not limited thereto. The light source device according to the present invention can also be applied to lighting fixtures, automobile headlights, and the like.

[0090] The 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 irradiates excitation light, a first surface, and a second surface different from the first surface, wavelength-converts the excitation light irradiated from the excitation light source and incident on the first surface to generate fluorescence, and emits at least fluorescence from the second surface. It includes a wavelength conversion element having a ceramic phosphor and a substrate that supports the ceramic phosphor. The ceramic phosphor includes a scattering element, and the surface roughness of the second surface is rougher than the surface roughness of the first surface.

[0091] In the light source device according to one aspect of the present invention, the scattering element may be configured as pores.

[0092] In the light source device according to one aspect of the present invention, the substrate may be made of a non-translucent material, the ceramic phosphor may include an exposed portion where a part of the first surface is exposed from the substrate, and the excitation light may be incident on the exposed portion of the ceramic phosphor.

[0093] In the light source device according to one aspect of the present invention, it may further include an optical layer provided on the first surface of the ceramic phosphor, transmitting the excitation light and reflecting the fluorescence.

[0094] In the light source device according to one aspect of the present invention, the wavelength conversion element may be a fixed-type wavelength conversion element in which the incident region of the excitation light on the ceramic phosphor does not change with time.

[0095] In the light source device according to one aspect of the present invention, the wavelength conversion element may be a rotation-type wavelength conversion element that changes the incident region of the excitation light on the ceramic phosphor with time by rotating the substrate around a predetermined rotation axis.

[0096] In the light source device according to one aspect of the present invention, the ceramic phosphor may include a third surface different from the first and second surfaces, and a reflective film provided on the third surface, and the light reflected by the reflective film may be emitted from the second surface.

[0097] In the light source device according to one aspect of the present invention, the thickness of the ceramic phosphor may be 40 μm or more and 300 μm or less.

[0098] 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 the light source device according to the above aspect of the present invention, a light modulation device that modulates the 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.

Description of Reference Numerals

[0099] 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

1. An excitation light source for irradiating excitation light, comprising a first surface and a second surface different from the first surface, converting the excitation light irradiated from the excitation light source and incident on the first surface into fluorescence, and emitting at least the fluorescence from the second surface. A wavelength conversion element having a ceramic phosphor, a substrate for supporting the ceramic phosphor, and a joining member for joining the ceramic phosphor and the substrate, wherein the ceramic phosphor contains a scattering element, the surface roughness of the second surface is rougher than the surface roughness of the first surface, the ceramic phosphor includes an exposed portion where a part of the first surface is exposed from the substrate, the excitation light is incident on the exposed portion of the ceramic phosphor, the first surface is disposed on the side opposite to the second surface, the first surface is joined to the substrate via the joining member, the joining member contains a conductive filler, the conductive filler contains at least one of MgO and AlN Light source device.

2. The scattering element is a pore The light source device according to claim 1.

3. The substrate is made of a non-transparent material The light source device according to claim 1 or claim 2.

4. 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 claim 3.

5. The wavelength conversion element is a fixed-type wavelength conversion element in which the incident region of the excitation light on the ceramic phosphor does not change with time The light source device according to any one of claims 1 to 4.

6. The wavelength conversion element is a rotary-type wavelength conversion element that changes the incident region of the excitation light on the ceramic phosphor with time by rotating the substrate around a predetermined rotation axis The light source device according to any one of claims 1 to 4.

7. 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 reflected by the reflective film is emitted from the second surface The light source device according to any one of claims 1 to 4.

8. The thickness of the ceramic phosphor is 40 μm or more and 300 μm or less The light source device according to any one of claims 1 to 7.

9. The light source device according to any one of claims 1 to 8, ​ ​ ​ ​ ​ ​ ​ ​ An optical modulation device that modulates the 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 includes a projector.

Images