Light source device and projector

Abstract

To provide a light source device and a projector that can efficiently utilize excitation light.SOLUTION: A light source device of the present invention comprises: an excitation light source that emits excitation light; a ceramic phosphor that has a first surface and a second surface, and emits, from the second surface, fluorescent light generated by converting a wavelength of part of the excitation light emitted from the excitation light source and incident from the first surface; and a substrate that supports the first surface of the ceramic phosphor. The excitation light emitted from the excitation light source is incident on an exposed portion exposed from the substrate on the first surface of the ceramic phosphor, and a distance from an area irradiated with the excitation light to the substrate in the exposed portion is 0.34 mm or more.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Conventionally, light source devices have been proposed that utilize the fluorescence emitted from a phosphor when the phosphor is irradiated with excitation light emitted from a light source. The following Patent Document 1 discloses a transmissive phosphor unit that emits fluorescence from a surface opposite to the surface on which the excitation light is incident. In this phosphor unit, a phosphor is provided on a transparent substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-3923 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the phosphor unit of Patent Document 1, excitation light passes through the transparent substrate and enters the phosphor, and a portion of the excitation light is reflected at the interface between the phosphor and the transparent substrate, becoming stray light within the transparent substrate and reducing the utilization efficiency of the excitation light. [Means for solving the problem]

[0005] In order to solve the above problems, according to one aspect of the present invention, there is provided a light source device comprising: a substrate; a transmissive ceramic phosphor supported on one side of the substrate and including an exposed surface with a first surface being partly exposed from the substrate; and an excitation light source that irradiates excitation light onto the exposed surface of the ceramic phosphor, wherein the distance from an irradiation area of ​​the excitation light on the exposed surface to the substrate is 0.34 mm or more.

[0006] According to another aspect of the present invention, there is provided a projector comprising a light source device of the second aspect described above, a light modulation device that modulates light emitted from the light source device in accordance with image information to form image light, and a projection optical device that projects the image light. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a projector according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing a schematic configuration of a light source device. [Diagram 3] 2 is a cross-sectional view showing a configuration of a main part of a wavelength conversion element. FIG. [Figure 4] FIG. 2 is a diagram showing the state of fluorescence emitted from a ceramic phosphor. [Diagram 5] FIG. 13 is a graph showing the relationship between the spread width of fluorescence due to bleeding and the BY ratio. [Figure 6] FIG. 11 is a cross-sectional view showing a configuration of a main part of a wavelength conversion element according to a second embodiment. [Figure 7] FIG. 11 is a cross-sectional view showing a configuration of a main part of a wavelength conversion element according to a third embodiment. [Figure 8] FIG. 11 is a cross-sectional view showing a configuration of a main part of a wavelength conversion element according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the drawings used in the following description may show characteristic parts in an enlarged scale for convenience in order to make the features easier to understand, and the dimensional ratios of each component may not necessarily be the same as the actual ones.

[0009] (First embodiment) Fig. 1 is a diagram showing a schematic configuration of a projector according to a first embodiment, and Fig. 2 is a diagram showing a schematic configuration of a light source device. 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 4R, a light modulation device 4G, and a light modulation device 4B, a synthesis 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, 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 reflects the green light LG and transmits the blue light LB, thereby separating the other light (green light LG and blue light LB) into the green light LG and 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 optical 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 optical modulation device 4B. The green light LG is reflected from the second dichroic mirror 7b toward the optical modulation device 4G.

[0013] The first relay lens 9a and the second relay lens 9b are disposed 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 a function of compensating for 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.

[0014] The light modulation device 4R modulates the red light LR according to image information to form image light corresponding to the red light LR. The light modulation device 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.

[0015] For example, a transmissive liquid crystal panel is used for the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B. A polarizing plate (not shown) is disposed on each of the entrance side and exit side of the liquid crystal panel.

[0016] Further, a field lens 10R, a field lens 10G, and a field lens 10B are arranged on the incident side of the optical modulation device 4R, the optical modulation device 4G, and the optical modulation device 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 optical modulation device 4R, the optical modulation device 4G, and the optical modulation device 4B, respectively.

[0017] The 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 light 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. The combining optical system 5 uses, for example, a cross dichroic prism.

[0018] The projection optical device 6 is made up of a group of projection lenses, and projects, in an enlarged form, the image light combined by the combining optical system 5 onto the screen SCR, thereby causing an enlarged image to be 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 focusing 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 is composed of 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 perpendicular to the illumination optical axis 100ax. The collimator lenses 10b are arranged in an array in a plane perpendicular to the illumination optical axis 100ax so as to correspond to each semiconductor laser 10a. The collimator lenses 10b convert 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 emitted from the excitation light source 10 and consisting of a parallel beam.

[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 uniform on the wavelength conversion element 20 described later, that is, a so-called top hat distribution. The homogenizer optical system 12, together with the focusing optical system 13, superimposes a plurality of small light beams emitted from a plurality of lenses of the first multi-lens array 12a and the second multi-lens array 12b on the wavelength conversion element 20. This makes the light intensity distribution of the excitation light E irradiated on the wavelength conversion element 20 uniform.

[0023] The focusing 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 formed of a convex lens. The focusing optical system 13 is disposed in the optical path from the homogenizer optical system 12 to the wavelength conversion element 20, and focuses the excitation light E to make 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 approximately 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 enters 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 superimposing 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 perpendicular 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 perpendicular to the illumination optical axis 100ax.

[0028] The second lens array 82, together with the superimposing lens 84, forms images of the first lenses 81a of the first lens array 81 near the image forming areas of the light modulation device 4R, the light modulation device 4G, and the light 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 phase difference plate (not shown).

[0030] The superimposing lens 84 collects the partial light beams emitted from the polarization conversion element 83 and superimposes them near the image forming areas of the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B.

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

[0032] 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 bonding member 24. The wavelength conversion element 20 of this embodiment is a fixed phosphor in which the incident position of the excitation light E on the ceramic phosphor 22 does not change over time.

[0033] The substrate 21 is made of a metal material having excellent heat dissipation properties, such as aluminum or copper. 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 a metal material having excellent heat dissipation properties, such as aluminum or copper. The substrate 21 of this embodiment has a higher thermal conductivity than the ceramic phosphor 22. The substrate 21 has a support surface 21a 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 a surface on which the excitation light E emitted from the excitation light source 10 is incident. The second surface 22b is a surface on which the fluorescence Y is emitted. The ceramic phosphor 22 of this embodiment is a transmissive wavelength conversion element that emits the fluorescence Y generated by the excitation light E incident from the first surface 22a from the second surface 22b opposite to the first surface 22a.

[0035] The ceramic phosphor 22 has a phosphor phase 25 and a matrix phase 26. The phosphor phase 25 contains an oxide phosphor to which an activator is added. For example, the phosphor phase 25 is yttrium aluminum garnet (YAG (Y3Al5O4)) to which cerium (Ce) is added as an activator. 12 ):Ce).

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

[0037] The oxide phosphor constituting the phosphor phase 25 is Y3Al5O 12 In addition, Y3(Al,Ga)5O 12 ,Lu3Al5O 12 ,TbAlO 12 The phosphor phase 25 may contain at least one of the following: Moreover, 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 that constitute the phosphor phase 25. The matrix phase 26 is made of a material containing MgO (magnesium oxide) as a translucent ceramic. The magnesium oxide that constitutes the matrix phase 26 has a thermal conductivity of approximately 50 W / m·K, and the YAG that constitutes the phosphor phase 25 has a thermal conductivity of approximately 12 W / m·K. In this 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 approximately 30 W / m·K, that of ZnO is approximately 25 W / m·K, that of TiO2 is approximately 43 W / m·K, that of Y2O3 is approximately 27 W / m·K, that of YAlO3 is approximately 12 W / m·K, that of BeO is approximately 250 W / m·K, and that of MgAl2O4 is approximately 14 W / m·K.

[0041] Such a ceramic phosphor 22 can be manufactured, for example, by the following process. The raw powders of YAG:Ce, namely Al2O3 powder, Y2O3 powder, and CeO2 powder, are mixed with a specified amount of ethanol and ball milled in a pot to produce a slurry. The slurry is dried, granulated, degreased, and sintered to obtain the YAG:Ce powder.

[0042] A predetermined amount of the YAG:Ce powder obtained in the above process is mixed with MgO powder and a predetermined amount of ethanol, and a slurry is generated by ball milling in a pot. The slurry is then dried and granulated, and molded, degreased, and sintered in order to obtain the ceramic phosphor 22 of this embodiment, which is a composite sintered body of YAG:Ce, YAG, and MgO (magnesium oxide). In order to increase the density of the sintered body, hot isostatic pressing may be performed, in which the sintered body is sintered under pressure.

[0043] The dichroic layer 23 is provided on the first surface 22a of the ceramic phosphor 22 as a reflective layer that reflects a specific wavelength. 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 prevent the fluorescence Y generated within the ceramic phosphor 22 from being emitted to the outside. This allows the fluorescence Y generated in the ceramic phosphor 22 to be efficiently extracted from the ceramic phosphor 22.

[0044] In the present embodiment, a through hole (opening) 210 is formed in the substrate 21. 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 part of the first surface 22a 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.

[0045] The ceramic phosphor 22 is bonded to the substrate 21 via a bonding member 24. The bonding member 24 of this embodiment contains a conductive filler with high thermal conductivity. The conductive filler contained in the bonding member 24 may be made of at least one of metal, Al2O3, ZrO2, MgO, and AlN. By using the bonding member 24 containing a conductive filler in this manner, the heat of the ceramic phosphor 22 can be efficiently transferred to the substrate 21.

[0046] The substrate 21 abuts against a region of the ceramic phosphor 22 different from the region where excitation light is incident. Therefore, the substrate 21 also functions as a member that dissipates heat generated in the ceramic phosphor 22. The substrate 21 abuts against the ceramic phosphor 22 in a portion other than the through hole 210.

[0047] The ceramic phosphor 22 of this embodiment emits white illumination light WL that is a combination of blue light (transmitted light) E1, which is a portion of the blue excitation light E emitted from the excitation light source 10 and 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.

[0048] 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 fluorescent light Y. Hereinafter, in this specification, this light amount ratio will be referred to as the BY ratio. The condition for obtaining a practical white balance for the illumination light WL used in a projector is a BY ratio of 30% to 50%.

[0049] It is known that the BY ratio is affected by the thickness of the ceramic phosphor 22. For example, by making the thickness of the ceramic phosphor 22 relatively thin, the amount of blue light E1 transmitted through the ceramic phosphor 22 can be increased. However, if the thickness of the ceramic phosphor 22 is thinner than 40 μm, it becomes difficult to manufacture the ceramic phosphor 22. Therefore, from the viewpoint of manufacturing, it is desirable to set the lower limit of the thickness of the ceramic phosphor 22 to 40 μm.

[0050] Furthermore, if the thickness of ceramic phosphor 22 is made relatively thick, the amount of blue light E1 passing through ceramic phosphor 22 decreases. Furthermore, if the thickness of ceramic phosphor 22 exceeds 150 μm, reabsorption of fluorescence Y is likely to occur within ceramic phosphor 22, and the amount of fluorescence Y that can be extracted from second surface 22b decreases. Therefore, from the viewpoint of light utilization efficiency of fluorescence Y, it is desirable to set the upper limit of the thickness of ceramic phosphor 22 to 150 μm.

[0051] 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 not less than 40 μm and not more than 150 μm.

[0052] 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 propagates to a region wider than the incidence region, causing the fluorescence emission region to expand in width, i.e., the so-called fluorescence bleeding occurs.

[0053] FIG. 4 is a diagram showing the state of fluorescence emitted from the ceramic phosphor 22. As shown in FIG. In the light source device 2 of this embodiment, an irradiation area SP of the excitation light E is formed on the exposed portion 211 of the ceramic phosphor 22. Therefore, as shown in Fig. 4, in the ceramic phosphor 22 of this embodiment, the width W2 of the light emission area of ​​the fluorescence Y in the exposed portion 211 becomes larger than the width W1 of the irradiation area SP due to the influence of bleeding. Note that, as shown in Fig. 4, the difference between the width W2 of the light emission area of ​​the fluorescence Y and the width W1 of the irradiation area SP corresponds to the spread width W3 of the fluorescence Y due to bleeding.

[0054] Here, consider a case where the light-emitting region of fluorescence Y on exposed portion 211 reaches substrate 21 due to bleeding. The state in which the light-emitting region of fluorescence Y reaches substrate 21 is equivalent to the state in which excitation light E reaches substrate 21. Therefore, when the light-emitting region of fluorescence Y reaches substrate 21, part of the excitation light E is directly incident on substrate 21 and absorbed, resulting in optical loss.

[0055] In contrast, in the light source device 2 of the present embodiment, the distance from the irradiation area SP of the excitation light E to the substrate 21 in the exposed portion 211 is made greater than a predetermined value, thereby preventing the excitation light E incident on the ceramic phosphor 22 from directly entering the substrate 21.

[0056] Fig. 5 is a diagram showing the relationship between the spread width of fluorescence due to bleeding and the BY ratio. The horizontal axis in Fig. 5 shows the spread width W3 (unit: mm) of fluorescence due to bleeding shown in Fig. 4. The vertical axis in Fig. 5 corresponds to the BY ratio (unit: %). Each graph in Fig. 5 shows the relationship between the spread width of fluorescence and the BY ratio for ceramic phosphors 22 of different thicknesses.

[0057] It can be seen from FIG. 5 that as the thickness of the ceramic phosphor 22 increases from 40 μm to 150 μm, the bleeding width of the Y fluorescence increases.

[0058] For example, when using a ceramic phosphor 22 with a minimum thickness (40 μm), it has been confirmed that in order to achieve the desired white balance (BY ratio 30% to 50%) for the illumination light WL emitted from the ceramic phosphor 22, the spread width of the fluorescence Y due to bleeding will be approximately 0.15 mm. Also, when using ceramic phosphor 22 with the upper limit thickness (150 μm), it can be confirmed that the spread width of fluorescence Y due to bleeding is approximately 0.31 mm in order to realize the desired white balance (BY ratio 30%) for the illumination light WL emitted from ceramic phosphor 22. Also, when using ceramic phosphor 22 with the upper limit thickness, it can be confirmed that the spread width of fluorescence Y is approximately 0.34 mm in order to realize the white balance of the illumination light WL (BY ratio 50%).

[0059] In the light source device 2 of this embodiment, when a desired white balance (BY ratio 30% to 50%) is achieved using a ceramic phosphor 22 with a thickness of 40 μm to 150 μm, the substrate 21 is spaced further away than the maximum spread width of the fluorescence Y (0.34 mm).

[0060] In the light source device 2 of this embodiment, the distance D from the irradiation area SP of the excitation light E to the through-hole 210 of the substrate 21 in the exposed portion 211 is set to 0.34 mm or more. As a result, even when a white balance with a BY ratio of 50% is achieved using a ceramic phosphor 22 with a thickness of 150 μm, at which the spread width of the fluorescence Y due to bleeding is the largest, the excitation light E does not reach the substrate 21. Note that the distance D is defined as the distance between the irradiation area SP and the inner surface of the through-hole 210 in the direction along the support surface 21a of the substrate 21.

[0061] (Effects of the first embodiment) The light source device 2 of this embodiment includes an excitation light source 10 that emits excitation light E, a ceramic phosphor 22 including a first surface 22a, and a substrate 21 that supports the first surface 22a of the ceramic phosphor 22, and the excitation light E emitted from the excitation light source 10 is incident on an exposed portion 211 of the first surface 22a that is exposed from the substrate 21, and the distance D from the irradiation area SP of the excitation light E to the substrate 21 in the exposed portion 211 is 0.34 mm or more.

[0062] According to the light source device 2 of the present embodiment, the excitation light E is directly incident on the ceramic phosphor 22 through the exposed portion 211, so that the excitation light E can be utilized more efficiently than in a configuration in which the excitation light is incident on the phosphor through a light-transmitting substrate. Furthermore, in the light source device 2 of this embodiment, the distance D from the irradiation area SP of the excitation light E to the substrate 21 in the exposed portion 211 is set to 0.34 mm or more, so that the excitation light E, which is diffusely reflected in the ceramic phosphor 22 and causes bleeding of the fluorescence Y, is prevented from being directly incident on the substrate 21. This prevents the absorption of the excitation light E by the substrate 21, thereby improving the light utilization efficiency of the excitation light E and thereby improving the conversion efficiency of the fluorescence Y.

[0063] In the light source device 2 of the present embodiment, the thickness of the ceramic phosphor 22 is not less than 40 μm and not more than 150 μm, the ceramic phosphor 22 includes a second surface 22b different from the first surface 22a, and converts the wavelength of a portion of the excitation light E irradiated to the exposed portion 211 of the first surface 22a to generate fluorescence Y and emits the fluorescence Y from the second surface 22b, while also emitting blue light E1, which is another portion of the excitation light E, from the second surface 22b, with the BY ratio of the blue light E1 to the fluorescence Y being desirably 30% to 50%.

[0064] In this way, by setting the BY ratio to 30% to 50%, illumination light WL with a proper white balance can be generated. Furthermore, by setting the thickness of the ceramic phosphor 22 to be 40 μm or more and 150 μm or less, the ceramic phosphor 22 can be easily manufactured.

[0065] In the light source device 2 of the present embodiment, the substrate 21 is made of a non-light-transmitting material having a higher thermal conductivity than the ceramic phosphor 22 .

[0066] According to this configuration, since the substrate 21 is made of a non-translucent material, it is possible to suppress the occurrence of loss due to the excitation light E leaking into the substrate 21. In addition, the substrate 21 can dissipate heat from the ceramic phosphor 22.

[0067] In the light source device 2 of the present embodiment, the exposed portion 211 of the ceramic phosphor 22 is exposed via a through-hole 210 formed in the substrate 21.

[0068] According to this configuration, the exposed portion 211 can be easily configured, and therefore the configuration of the light source device itself can be made compact.

[0069] The light source device 2 of this embodiment further includes a dichroic layer 23 that is provided on the first surface 22a of the ceramic phosphor 22 and transmits the excitation light E and reflects the fluorescence Y.

[0070] According to this configuration, since the first surface 22a is provided with the dichroic layer 23, it is possible to prevent the fluorescence Y generated within the ceramic phosphor 22 from being emitted to the outside. This makes it possible to efficiently extract the fluorescence Y generated in the ceramic phosphor 22 from the ceramic phosphor 22.

[0071] The projector 1 of this embodiment includes a light source device 2, light modulation devices 4R, 4G, and 4B that modulate the light emitted from the light source device 2 in accordance with image information to form image light, and a projection optical device 6 that projects the image light.

[0072] 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, and therefore a high-quality image can be displayed.

[0073] Second embodiment A second embodiment of the present invention will now be described with reference to FIG. The schematic configuration of the projector of the second embodiment is similar to that of the first embodiment, but the configuration of the wavelength conversion element in the light source device is different from that of the first embodiment. Therefore, the following describes the configuration of the wavelength conversion element, and descriptions of other configurations are omitted.

[0074] 6 is a cross-sectional view showing a main configuration of a wavelength conversion element of this embodiment. As shown in FIG 6, a wavelength conversion element 120 of this embodiment includes a substrate 21, a ceramic phosphor 122, a dichroic layer 23, and a bonding member 24.

[0075] The ceramic phosphor 122 has a first surface 122a and a second surface 122b. The first surface 122a is a surface onto which the excitation light E emitted from the excitation light source 10 is incident. The second surface 122b is a surface from which the fluorescence Y is emitted. The ceramic phosphor 122 has a recess 123 formed on the second surface 122b.

[0076] In this embodiment, the ceramic phosphor 122 includes a first region A1 and a second region A2. The first region A1 is a region including the irradiation region SP of the excitation light E, and is a region in which the recess 123 is provided. The second region A2 is a region different from the first region A1, and is a region surrounding the periphery of the first region A1. When viewed in plan from the second surface 22b side, the second region A2 is a region located closer to the substrate 21 (outer side) than the fluorescence emission region A3 that emits the fluorescence Y. In other words, the fluorescence Y is not emitted from the second region A2. In the present embodiment, the thickness of the first region A1 is thinner than the thickness of the second region A2 by providing the recess 123 as described above. The thicknesses of the first region A1 and the second region A2 are both 40 μm or more and 150 μm or less.

[0077] In the ceramic phosphor 122, the boundary BL between the first region A1 and the second region A2 is located between the irradiation region SP of the excitation light E and the substrate 21, and therefore the first region A1, which is relatively thin, is not disposed on the substrate 21. In the thickness direction of the substrate 21 (the vertical direction in FIG. 6), a part of the second region A2 overlaps with the substrate 21. That is, the second region A2 is joined to the substrate 21 via the joining member 24.

[0078] Also in the wavelength conversion element 120 of this embodiment, the distance D from the irradiation area SP of the excitation light E in the exposed portion 211 to the substrate 21 is set to 0.34 mm or more.

[0079] (Effects of the second embodiment) In the wavelength conversion element 120 of this embodiment, the thickness of the first region A1 into which the excitation light E is incident is made relatively thin, thereby suppressing waveguiding of the fluorescence Y in the ceramic phosphor 122 and suppressing an increase in the area of ​​the fluorescence emission region A3. This makes it possible to suppress an increase in the etendue of the fluorescence Y. In addition, by making the thickness of the second region A2, which is located outside the fluorescence emission region A3 and is joined to the substrate 21, relatively thick, it is possible to reduce the thermal resistance of the path for dissipating the heat generated in the first region A1 to the substrate 21. This improves the heat dissipation of the ceramic phosphor 122, thereby improving the conversion efficiency of the fluorescence Y and generating bright fluorescence Y. Furthermore, in the wavelength conversion element 120 of the present embodiment, by bonding the second region A2, which is relatively thick, to the substrate 21, the shear force of the ceramic phosphor 122 can be improved and damage to the ceramic phosphor 122 can be suppressed.

[0080] Therefore, according to the light source device equipped with the wavelength conversion element 120 of this embodiment, the absorption of the excitation light E by the substrate 21 is suppressed, and the conversion efficiency of the fluorescence Y can be improved by efficiently utilizing the excitation light E, so that bright illumination light WL can be generated.

[0081] Third embodiment Hereinafter, a third embodiment of the present invention will be described with reference to FIG. The schematic configuration of the projector of the third embodiment is similar to that of the first embodiment, but the configuration of the wavelength conversion element in the light source device is different from that of the first embodiment. Therefore, the following describes the configuration of the wavelength conversion element, and descriptions of other configurations are omitted.

[0082] Fig. 7 is a cross-sectional view showing the main configuration of the wavelength conversion element of this embodiment. As shown in Fig. 7, the wavelength conversion element 220 of this embodiment includes a substrate 121, a ceramic phosphor 222, a dichroic layer 23, and a motor 125. The wavelength conversion element 220 of this embodiment is a rotating wheel type wavelength conversion element that changes the incident position of the excitation light E with respect to the ceramic phosphor 222 over time.

[0083] The substrate 121 is made of a metal material with excellent heat dissipation properties, such as aluminum or copper. The substrate 121 is a rotatable substrate that is rotatable 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.

[0084] The ceramic phosphor 222 of this embodiment is formed in an annular shape around the rotation axis O. The ceramic phosphor 222 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 heat generated by the ceramic phosphor 222.

[0085] A dichroic layer 23 is provided on a first surface 222a of the ceramic phosphor 222. A radially inner end 222a1 of the first surface 222a of the annular ceramic phosphor 222 is fixed to the substrate 21 via a bonding member 24. That is, when viewed from above in a 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 a protruding portion (exposed portion) 1220 of the ceramic phosphor 122 protruding radially outward from the substrate 21. In this embodiment, the substrate 21 abuts on a region of the ceramic phosphor 222 different from the incidence region of the excitation light E, and dissipates heat generated in the ceramic phosphor 322.

[0086] In the wavelength conversion element 220 of this embodiment, the excitation light E is incident on the protruding portion 1220 of the ceramic phosphor 122 in a rotating state. When the excitation light E is incident on the ceramic phosphor 222, heat is generated in the protruding portion 1220 of the ceramic phosphor 222. In this embodiment, the motor 125 rotates the ceramic phosphor 222 to move the incident position of the excitation light E on the protruding portion 1220 of the ceramic phosphor 222 over time. As a result, the excitation light E is constantly irradiated to the same position of the protruding portion 1220 of the ceramic phosphor 222, so that only a part of the ceramic phosphor 222 is locally heated, and deterioration of the ceramic phosphor 222 is suppressed.

[0087] In the present embodiment, by rotating the ceramic phosphor 222, the heat dissipation property of the ceramic phosphor 222 can be further improved.

[0088] In the wavelength conversion element 220 of this embodiment, the substrate 21 in contact with the ceramic phosphor 222 is also made of a non-translucent material. As a result, in the wavelength conversion element 220, the fluorescence Y generated in the ceramic phosphor 222 is efficiently extracted to the outside without leaking out to the substrate 121.

[0089] Also in the wavelength conversion element 220 of this embodiment, the distance D from the irradiation area SP of the excitation light E in the protruding portion 1220 to the substrate 121 is set to 0.34 mm or more.

[0090] (Effects of the third embodiment) According to the light source device including the wavelength conversion element 220 of this embodiment, when a rotational wavelength conversion element is used, similarly to the first embodiment, absorption of the excitation light E by the substrate 121 can be suppressed, and the excitation light E can be efficiently used. In addition, by improving the heat dissipation in the ceramic phosphor 222, a decrease in the amount of fluorescence due to a decrease in the wavelength conversion efficiency of the ceramic phosphor 222 can be suppressed.

[0091] (Fourth embodiment) A fourth embodiment of the present invention will be described below with reference to FIG. The schematic configuration of the projector of the fourth embodiment is the same as that of the third embodiment, but the configuration of the wavelength conversion element in the light source device is different from that of the third embodiment. Specifically, the wavelength conversion element of this embodiment has a structure that combines the configuration of the wavelength conversion element of the third embodiment with the configuration of the second embodiment. Below, the configuration of the wavelength conversion element will be described, and descriptions of other configurations will be omitted.

[0092] FIG. 8 is a cross-sectional view showing a configuration of a main part of the wavelength conversion element of this embodiment. 8, the wavelength conversion element 320 of this embodiment includes a substrate 121, a ceramic phosphor 322, a dichroic layer 23, and a motor 125. The wavelength conversion element 320 of this embodiment is a rotating wheel type wavelength conversion element that changes the incident position of the excitation light E with respect to the ceramic phosphor 322 over time.

[0093] The ceramic phosphor 322 has a first surface 322a on which the excitation light E emitted from the excitation light source 10 is incident, and a second surface 322b from which the fluorescence Y is emitted. The ceramic phosphor 322 has a recess 323 formed in a predetermined region of the second surface 322b.

[0094] The ceramic phosphor 322 of this embodiment includes a first region A11 and a second region A12. The first region A11 is a region including the irradiation region SP of the excitation light E, and is a region in which the recess 323 is provided. The second region A12 is a region different from the first region A11, and is a ring-shaped region located radially inside the first region A11. The thickness of the first region A11 is thinner than the thickness of the second region A12. In this embodiment, the protruding portion 1320 of the ceramic phosphor 322 is composed of the first region A11 and a part of the second region A12. In this embodiment, since the recess 323 is provided as described above, the thickness of the first region A11 is thinner than the thickness of the second region A12. The thicknesses of the first region A11 and the second region A12 are both 40 μm or more and 150 μm or less.

[0095] In the thickness direction of the substrate 121 (the vertical direction in FIG. 8), a part of the second region A12 overlaps with the substrate 121. That is, the second region A12 is joined to the substrate 121 via the joining member 24. In the ceramic phosphor 322, the boundary BL between the first region A11 and the second region A12 is located between the irradiation region SP of the excitation light E and the substrate 121. In the wavelength conversion element 320 of this embodiment as well, the distance D from the irradiation region SP of the excitation light E in the protruding portion 1220 to the substrate 21 is set to 0.34 mm or more.

[0096] (Effects of the fourth embodiment) In the wavelength conversion element 320 of this embodiment, when a rotational wavelength conversion element is used, similarly to the second embodiment, the heat dissipation of the ceramic phosphor 322 is improved to improve the fluorescence conversion efficiency and generate bright fluorescence Y. In addition, by bonding to the substrate 121 in the second region A12, damage to the ceramic phosphor 322 can be suppressed. In addition, by improving the heat dissipation of the ceramic phosphor 322, the conversion efficiency of the fluorescence Y is improved, and therefore brighter illumination light WL can be generated.

[0097] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the case where the entire substrate 21, 121 is made of a non-light-transmitting material (metal) has been exemplified, but leakage of the fluorescence Y can be prevented if at least the portion of the substrate 21, 121 that abuts against any of the ceramic phosphors 22, 122, 222, 322 is made of a non-light-transmitting material. Therefore, the substrate 21, 121 may be made of a light-transmitting material other than the portion that abuts against any of the ceramic phosphors 22, 122, 222, 322.

[0098] Also, for example, in the ceramic phosphors 22, 122, 222, and 322 of the above-mentioned embodiments, the phosphor phase 25 contains an oxide phosphor, and the matrix phase 26 contains a metal oxide. Instead of this configuration, the phosphor phase 25 may contain a nitride phosphor, and the matrix phase 26 may contain a metal nitride. As the nitride phosphor, for example, a sialon phosphor such as α-SiAlON or β-SiAlON may be used. As the metal nitride, for example, AlN may be used. The thermal conductivity of AlN is 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, unnecessary oxidation reactions and the like do not occur in each phase, and the ceramic phosphor can be stably manufactured.

[0099] In addition, the specific description of the shape, number, arrangement, material, manufacturing method, etc. of each component of the light source device and the projector is not limited to the above embodiment and can be changed as appropriate. 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 is shown, but this is not limiting. 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.

[0100] In the above embodiment, the light source device according to the present invention is mounted on a projector, 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.

[0101] The light source device according to the aspect of the present invention may have the following configuration. One embodiment of the light source device of the present invention comprises an excitation light source that emits excitation light, a ceramic phosphor that includes a first surface and a second surface and emits fluorescence generated by wavelength-converting a portion of the excitation light emitted from the excitation light source and incident on the first surface from the second surface, and a substrate that supports the first surface of the ceramic phosphor, wherein the excitation light emitted from the excitation light source is incident on an exposed portion of the first surface of the ceramic phosphor that is exposed from the substrate, and the distance from the irradiation area of ​​the excitation light to the substrate in the exposed portion is 0.34 mm or more.

[0102] In one embodiment of the light source device of the present invention, the thickness of the ceramic phosphor is 40 μm or more and 150 μm or less, and the ceramic phosphor emits another portion of the excitation light as transmitted light from the second surface together with the fluorescence, and the light intensity ratio between the transmitted light and the fluorescence emitted from the ceramic phosphor may be 30% to 50%.

[0103] In a light source device according to one embodiment of the present invention, the ceramic phosphor has a first region and a second region, the first region is a region including an irradiation region of excitation light, the second region is a region located closer to the substrate than a fluorescence emission region that emits fluorescence, and the thickness of the first region is greater than the thickness of the second region. ThinThe substrate may have a higher thermal conductivity than the ceramic phosphor, and at least a portion of the second region may overlap with the substrate in a thickness direction of the substrate.

[0104] In the light source device according to one aspect of the present invention, in the ceramic phosphor, the boundary between the first region and the second region may be located between the region irradiated with excitation light and the substrate.

[0105] In the light source device according to one aspect of the present invention, the exposed portion of the ceramic phosphor may be exposed through an opening formed in the substrate.

[0106] 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 for transmitting the excitation light and reflecting the fluorescent light.

[0107] In one embodiment of the light source device of the present invention, the substrate is a rotating substrate that rotates around a predetermined rotation axis, and the ceramic phosphor is arranged so as to protrude radially outward from the substrate, and the portion of the ceramic phosphor that protrudes from the substrate may be an exposed portion.

[0108] A projector according to one aspect of the invention may have the following configuration. A projector according to one aspect of the present invention comprises a 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 in accordance with image information to form image light, and a projection optical device that projects the image light. [Explanation of symbols]

[0109] 1...projector, 2...light source device, 4B, 4G, 4R...light modulation device, 6...projection optical device, 10...excitation light source, 21, 121...substrate, 22, 122, 222, 322...ceramic phosphor, 22a, 122a, 222a, 322a...first surface, 22b, 122b, 322b...second surface, 23...dichroic layer (optical layer), 210...through hole (opening), 211...exposed portion, 1220, 1320...protruding portion (exposed portion), A1, A11...first region, A2, A12...second region, A3...fluorescence emission region, BL...boundary (boundary between first region and second region), D...distance, E...excitation light, E1...blue light (transmitted light), O...rotation axis, SP...irradiation region, Y...fluorescence.

Claims

1. an excitation light source that emits excitation light; a ceramic phosphor including a first surface and a second surface, the ceramic phosphor generating fluorescence by wavelength-converting a portion of the excitation light emitted from the excitation light source and incident on the first surface, and emitting the fluorescence from the second surface; a substrate supporting the first surface of the ceramic phosphor; the excitation light emitted from the excitation light source is incident on an exposed portion of the first surface of the ceramic phosphor that is exposed from the substrate, a distance from an irradiation area of ​​the excitation light to the substrate in the exposed portion is 0.34 mm or more; The ceramic phosphor has a first region and a second region, the first region is a region including an irradiation region of the excitation light, the second region is a region located closer to the substrate than a fluorescence emission region that emits the fluorescence, The thickness of the first region is smaller than the thickness of the second region, At least a portion of the second region overlaps with the substrate in a thickness direction of the substrate. Light source device.

2. In the ceramic phosphor, the boundary between the first region and the second region is located between the region irradiated with the excitation light and the substrate. The light source device according to claim 1 .

3. an excitation light source that emits excitation light; a ceramic phosphor including a first surface and a second surface, the ceramic phosphor generating fluorescence by wavelength-converting a portion of the excitation light emitted from the excitation light source and incident on the first surface, and emitting the fluorescence from the second surface; a substrate supporting the first surface of the ceramic phosphor; the excitation light emitted from the excitation light source is incident on an exposed portion of the first surface of the ceramic phosphor that is exposed from the substrate, a distance from an irradiation area of ​​the excitation light to the substrate in the exposed portion is 0.34 mm or more; the substrate is a rotating substrate that rotates around a predetermined rotation axis, The ceramic phosphor is provided on the substrate so as to protrude radially outward from the substrate, The portion of the ceramic phosphor protruding from the substrate is the exposed portion. Light source device.

4. The exposed portion of the ceramic phosphor is exposed through an opening formed in the substrate. The light source device according to claim 3 .

5. The thickness of the ceramic phosphor is 40 μm or more and 150 μm or less, the ceramic phosphor emits another portion of the excitation light as transmitted light from the second surface together with the fluorescent light, The ratio of the amount of light between the transmitted light and the fluorescent light emitted from the ceramic phosphor is 30% to 50%. The light source device according to any one of claims 1 to 4.

6. The substrate is made of a non-transparent material having a higher thermal conductivity than the ceramic phosphor. The light source device according to any one of claims 1 to 5.

7. an optical layer provided on the first surface of the ceramic phosphor to transmit the excitation light and reflect the fluorescent light; The light source device according to any one of claims 1 to 6.

8. A light source device according to any one of claims 1 to 7, a light modulation device that modulates the light emitted from the light source device in accordance with image information to form image light; a projection optical device that projects the image light; projector.

Images