Wavelength converter, method for manufacturing wavelength converter, light source device, and projector

Abstract

To provide a wavelength converter, a method for manufacturing a wavelength converter, a light source device, and a projector which can attain the joint intensity and the cooling efficiency of a wavelength converter layer.SOLUTION: The wavelength converter according to the present invention includes: a wavelength conversion layer having a first surface for light to enter and a second surface opposed to the first surface, the wavelength conversion layer converting entering light; a substrate arranged on the second surface side of the wavelength conversion layer; and a joint layer for joining the substrate and the wavelength conversion layer to each other. The joint layer includes: a first layer facing the substrate; and a second layer arranged between the first layer and the wavelength conversion layer. The void ratio of the first layer is higher than the void ratio of the second layer.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a wavelength converter, a method for manufacturing a wavelength converter, a light source device, and a projector. [Background technology]

[0002] In recent years, there are lighting devices that use fluorescence as illumination light. For example, the following Patent Document 1 discloses a lighting device that includes a light source that emits laser light and a wavelength conversion device that emits fluorescence when the laser light is incident. In this lighting device, the wavelength conversion device includes a phosphor layer, a heat dissipation substrate provided on the side of the phosphor layer opposite to the side where the excitation light is incident, and a bonding layer that bonds the phosphor layer and the heat dissipation substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-129354 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned lighting device, the expansion coefficients of the phosphor layer and the heat dissipation substrate are different from each other, so when the phosphor layer generates heat, the difference in the thermal expansion coefficients causes thermal stress, which may cause the phosphor layer to peel off or break. In addition, it is possible to improve the bonding strength of the phosphor layer by alleviating the thermal stress using a bonding layer with voids inside, but this creates a new problem in that the thermal conductivity of the bonding layer is reduced by the voids, reducing the cooling efficiency of the phosphor layer. [Means for solving the problem]

[0005] In order to solve the above problems, according to a first aspect of the present invention, there is provided a wavelength conversion device comprising: a wavelength conversion layer having a first surface onto which light is incident and a second surface opposite to the first surface, and converting the incident light; a substrate arranged on the second surface side of the wavelength conversion layer; and a bonding layer bonding the substrate and the wavelength conversion layer, wherein the bonding layer has a first metal layer facing the substrate and a second metal layer arranged between the first metal layer and the wavelength conversion layer, and the porosity of the first metal layer is higher than the porosity of the second metal layer.

[0006] According to a second aspect of the present invention, there is provided a light source device comprising: a wavelength converter according to the first aspect; and a light emitting element that emits the light to the wavelength converter.

[0007] According to a third aspect of the present invention, there is provided a projector comprising a light source device according to the second aspect, an optical modulation device that varies the amount of light emitted from the light source device based on image information, and a projection optical device that projects the light emitted from the modulation device.

[0008] According to a fourth aspect of the present invention, there is provided a method for manufacturing a wavelength conversion device comprising a wavelength conversion layer, a substrate, and a bonding layer bonding the substrate and the wavelength conversion layer, the bonding layer having a first metal layer facing the substrate, and a second metal layer having a higher porosity than the first metal layer and disposed between the first metal layer and the wavelength conversion layer, the method comprising: a first step of arranging a first metal material on the substrate; a second step of arranging a second metal material having a smaller particle size than the first metal material on the wavelength conversion layer; and a third step of sintering the first metal material to form the first metal layer and sintering the second metal material to form the second metal layer to form the bonding layer.

[0009] According to a fifth aspect of the present invention, there is provided a method for manufacturing a wavelength conversion device comprising a wavelength conversion layer, a substrate, and a bonding layer bonding the substrate and the wavelength conversion layer, the bonding layer having a first metal layer facing the substrate, and a second metal layer having a higher porosity than the first metal layer and disposed between the first metal layer and the wavelength conversion layer, the method comprising: a first step of arranging a first metal material on the substrate; a second step of arranging a second metal material on the wavelength conversion layer; and a third step of sintering the first metal material to form the first metal layer, and sintering the second metal material at a sintering temperature higher than the sintering temperature of the first metal material to form the second metal layer to serve as the bonding layer. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a projector according to a first embodiment. [Diagram 2] FIG. 1 is a diagram showing a schematic configuration of a lighting device. [Diagram 3] 1 is a cross-sectional view showing a configuration of a main part of a wavelength conversion device. [Figure 4] 1 is an image showing a configuration of a main part of a bonding layer. [Figure 5A] 1A to 1C are diagrams each showing a part of a manufacturing process of a wavelength converter. [Figure 5B] 1A to 1C are diagrams each showing a part of a manufacturing process of a wavelength converter. [Figure 5C] 1A to 1C are diagrams each showing a part of a manufacturing process of a wavelength converter. [Figure 6] FIG. 11 is a cross-sectional view showing a configuration of a main part of a wavelength converter according to a second embodiment. [Figure 7] FIG. 11 is a cross-sectional view showing a configuration of a main part of a wavelength converter according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 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.

[0012] (First embodiment) First, an example of a projector according to this embodiment will be described. FIG. 1 is a diagram showing a schematic configuration of a projector according to this embodiment. 1, the projector 1 of this embodiment is a projection type image display device that displays a color image on a screen SCR. The projector 1 includes an illumination device 2, a color separation optical system 3, a light modulation device 4R, a light modulation device 4G, a light modulation device 4B, a synthesis optical system 5, and a projection optical system 6.

[0013] The color separation optical system 3 separates the illumination light WL into red light LR, green light LG, and blue light LB. The color separation optical system 3 generally includes a first dichroic mirror 7a, a second dichroic mirror 7b, a first reflecting mirror 8a, a second reflecting mirror 8b, and a third reflecting mirror 8c, and a first relay lens 9a and a second relay lens 9b.

[0014] The first dichroic mirror 7a separates the illumination light WL from the illumination device 2 into red light LR and other light (green light LG and blue light LB). The first dichroic mirror 7a transmits the separated 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 into the green light LG and blue light LB.

[0015] The first reflecting 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 reflecting mirror 8b and the third reflecting 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.

[0016] The first relay lens 9a and the second relay lens 9b are disposed after the second dichroic mirror 7b in the optical path of the blue light LB.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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 system 6. The combining optical system 5 uses, for example, a cross dichroic prism.

[0021] The projection optical system 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 displaying an enlarged color image on the screen SCR.

[0022] (Lighting equipment) Next, the illumination device 2 according to this embodiment will be described. Fig. 2 is a diagram showing a schematic configuration of the illumination device 2. As shown in Fig. 2, the illumination device 2 includes a light source device 2A, an integrator optical system 31, a polarization conversion element 32, and a superimposing lens 33a. In this embodiment, the integrator optical system 31 and the superimposing lens 33a configure a superimposing optical system 33.

[0023] The light source device 2A includes an array light source 21A, a collimator optical system 22, an afocal optical system 23, a first retardation plate 28a, a polarization separation element 25, a first focusing optical system 26, a wavelength conversion device 40, a second retardation plate 28b, a second focusing optical system 29, and a diffuse reflection element 30.

[0024] The array light source 21A, the collimator optical system 22, the afocal optical system 23, the first retardation plate 28a, the polarization separation element 25, the second retardation plate 28b, the second focusing optical system 29, and the diffuse reflection element 30 are arranged in sequence on the optical axis ax1. Meanwhile, the wavelength conversion device 40, the first focusing optical system 26, the polarization separation element 25, the integrator optical system 31, the polarization conversion element 32, and the superimposing lens 33a are arranged in sequence on the illumination optical axis ax2. The optical axis ax1 and the illumination optical axis ax2 are in the same plane and are perpendicular to each other.

[0025] The array light source 21A includes a plurality of semiconductor lasers 211 as solid-state light sources. The plurality of semiconductor lasers 211 are arranged in an array in a plane perpendicular to the optical axis ax1. The semiconductor laser 211 emits, for example, a blue light beam BL (for example, a laser beam having a peak wavelength of 460 nm). The array light source 21A emits a light beam consisting of a plurality of light beams BL. In this embodiment, the array light source 21A corresponds to the "light source" in the claims.

[0026] The light beam BL emitted from the array light source 21A enters the collimator optical system 22. The collimator optical system 22 converts the light beam BL emitted from the array light source 21A into parallel light. The collimator optical system 22 is composed of a plurality of collimator lenses 22a arranged, for example, in an array. The plurality of collimator lenses 22a are arranged corresponding to the plurality of semiconductor lasers 211.

[0027] The light beam BL that has passed through the collimator optical system 22 enters the afocal optical system 23 . The afocal optical system 23 adjusts the beam diameter of the light beam BL. The afocal optical system 23 is composed of, for example, a convex lens 23a and a concave lens 23b.

[0028] The light ray BL that has passed through the afocal optical system 23 is incident on the first retardation plate 28a. The first retardation plate 28a is, for example, a rotatable half-wave plate. The light ray BL emitted from the semiconductor laser 211 is linearly polarized light. By appropriately setting the rotation angle of the first retardation plate 28a, the light ray BL that passes through the first retardation plate 28a can be made to contain a predetermined ratio of S-polarized component and P-polarized component with respect to the polarization separation element 25. By rotating the first retardation plate 28a, the ratio of the S-polarized component and the P-polarized component can be changed.

[0029] The light beam BL, which contains an S-polarized component and a P-polarized component generated by passing through the first retardation plate 28a, enters the polarization separation element 25. The polarization separation element 25 is composed of, for example, a polarizing beam splitter having wavelength selectivity. The polarization separation element 25 also forms an angle of 45° with respect to the optical axis ax1 and the illumination optical axis ax2.

[0030] The polarization separation element 25 has a polarization separation function of separating the light ray BL into a light ray BLs having an S-polarized component and a light ray BLp having a P-polarized component relative to the polarization separation element 25. Specifically, the polarization separation element 25 reflects the light ray BLs having an S-polarized component and transmits the light ray BLp having a P-polarized component.

[0031] The polarized light separating element 25 also has a color separating function of transmitting the fluorescent light YL, which has a different wavelength band from that of the light BL, regardless of its polarization state.

[0032] The S-polarized light beam BLs emitted from the polarization separation element 25 is incident on the first focusing optical system 26. The first focusing optical system 26 focuses the light beam BLs toward the wavelength conversion device 40.

[0033] In this embodiment, the first focusing optical system 26 is composed of, for example, a first lens 26a and a second lens 26b. The light beam BLs emitted from the first focusing optical system 26 is incident on the wavelength conversion device 40 in a focused state.

[0034] The fluorescence YL generated by the wavelength conversion device 40 is collimated by the first light collecting optical system 26 and then enters the polarization separation element 25. The fluorescence YL passes through the polarization separation element 25.

[0035] On the other hand, the P-polarized light ray BLp emitted from the polarization separation element 25 is incident on the second retardation plate 28b. The second retardation plate 28b is composed of a quarter-wave plate arranged in the optical path between the polarization separation element 25 and the diffuse reflection element 30. Therefore, the P-polarized light ray BLp emitted from the polarization separation element 25 is converted by the second retardation plate 28b into, for example, right-handed circularly polarized blue light BLc1, and then enters the second focusing optical system 29. The second focusing optical system 29 is composed of, for example, convex lenses 29a and 29b, and causes the blue light BLc1 to be incident on the diffuse reflecting element 30 in a focused state.

[0036] The diffuse reflecting element 30 is disposed on the opposite side of the polarization separation element 25 to the phosphor layer 42, and diffusely reflects the blue light BLc1 emitted from the second light collecting optical system 29 toward the polarization separation element 25. It is preferable to use, as the diffuse reflecting element 30, an element that reflects the blue light BLc1 in a Lambertian manner while not disturbing the polarization state.

[0037] Hereinafter, the light diffusely reflected by the diffuse reflecting element 30 is referred to as blue light BLc2. According to this embodiment, blue light BLc2 having a substantially uniform illuminance distribution is obtained by diffusively reflecting blue light BLc1. For example, right-handed circularly polarized blue light BLc1 is reflected as left-handed circularly polarized blue light BLc2.

[0038] The blue light BLc2 is converted into parallel light by the second focusing optical system 29 and then enters the second retardation plate 28b again.

[0039] The left-handed circularly polarized blue light BLc2 is converted by the second retardation plate 28b into S-polarized blue light BLs1. The S-polarized blue light BLs1 is reflected by the polarization separation element 25 towards the integrator optical system 31.

[0040] As a result, the blue light BLs1 is used as illumination light WL together with the fluorescence YL transmitted through the polarization separation element 25. That is, the blue light BLs1 and the fluorescence YL are emitted in the same direction from the polarization separation element 25, and white illumination light WL is generated in which the blue light BLs1 and the fluorescence (yellow light) YL are mixed together.

[0041] The illumination light WL is emitted toward the integrator optical system 31. The integrator optical system 31 is composed of, for example, a lens array 31a and a lens array 31b. The lens arrays 31a and 31b are each composed of a plurality of small lenses arranged in an array.

[0042] The illumination light WL transmitted through the integrator optical system 31 is incident on the polarization conversion element 32 . The polarization conversion element 32 is composed of a polarization separation film and a phase difference plate, and converts the illumination light WL containing the unpolarized fluorescence YL into linearly polarized light.

[0043] The illumination light WL transmitted through the polarization conversion element 32 is incident on the superimposing lens 33a. The superimposing lens 33a homogenizes the distribution of illuminance of the illumination light WL in the illuminated area in cooperation with the integrator optical system 31. In this manner, the illumination device 2 generates the illumination light WL.

[0044] (Wavelength conversion device) 3 is a cross-sectional view showing a configuration of a main part of the wavelength converter 40. Hereinafter, the light BLs emitted from the first light collecting optical system 26 and incident on the phosphor layer 42 will be referred to as excitation light BLs. As shown in FIG. 3, the wavelength conversion device 40 includes a substrate 41, a phosphor layer 42, and a bonding layer 50. The wavelength conversion device 40 of this embodiment has a fixed type configuration in which the substrate 41 does not rotate. The substrate 41 has a surface 41a facing the first focusing optical system 26 and a back surface 41b opposite to the surface 41a. The bonding layer 50 bonds the substrate 41 and the phosphor layer 42. The wavelength conversion device 40 of this embodiment further includes a reflective member 43 provided between the bonding layer 50 and the phosphor layer 42. In this embodiment, the phosphor layer 42 corresponds to the "wavelength conversion layer" described in the claims. In addition, hereinafter, the state in which the wavelength conversion device 40 is viewed along the normal direction of the first surface 42a, which is the incident direction of the excitation light BLs onto the phosphor layer 42, i.e., the direction in which the chief ray of the excitation light BLs enters the phosphor layer 42, may be referred to as the "planar state."

[0045] The material of the substrate 41 is preferably a material having high thermal conductivity and excellent heat dissipation properties, and examples of such materials include metals such as aluminum and copper, and ceramics such as aluminum nitride, alumina, sapphire, diamond, etc. In this embodiment, the substrate 41 is formed using copper. In addition, by providing a heat dissipation member made of a heat sink on rear surface 41b of substrate 41, the heat dissipation properties of substrate 41 may be further improved and thermal deterioration of phosphor layer 42 may be suppressed.

[0046] In this embodiment, the phosphor layer 42 is a ceramic phosphor formed by firing phosphor particles. As the phosphor particles constituting the phosphor layer 42, a YAG (Yttrium Aluminum Garnet) phosphor containing Ce ions is used.

[0047] The phosphor particles may be made of one material, or may be made of a mixture of particles formed using two or more materials. As the phosphor layer 42, a phosphor layer in which phosphor particles are dispersed in an inorganic binder such as alumina, or a phosphor layer formed by firing an inorganic material, such as a glass binder, and phosphor particles, may be suitably used. The phosphor layer may also be formed by firing phosphor particles without using a binder.

[0048] The phosphor layer 42 is held on a surface 41a of the substrate 41 via a bonding layer 50, which will be described later. The phosphor layer 42 has a first surface 42a on which the excitation light BLs is incident and from which fluorescence YL obtained by wavelength-converting the excitation light BLs is emitted, and a surface opposite to the first surface 42a, i.e., a second surface 42b on which the reflecting member 43 and the substrate 41 are provided. That is, in this embodiment, the substrate 41 is disposed on the opposite side to the first surface 42a on which the excitation light BLs of the phosphor layer 42 is incident. The reflecting member 43 reflects the light incident from the phosphor layer 42 toward the first focusing optical system 26.

[0049] The phosphor layer 42 has light scattering properties due to a plurality of pores provided therein. Some of the plurality of pores are formed on the second surface 42b of the phosphor layer 42, and therefore the pores cause unevenness on the second surface 42b of the phosphor layer 42. The phosphor layer 42 of this embodiment includes a planarization film 45 that planarizes the second surface 42b. The planarization film 45 is made of an inorganic material having translucency, such as SiO2. The planarization film 45 fills the unevenness of the second surface 42b to planarize the second surface 42b.

[0050] The reflective member 43 of the present embodiment is configured by laminating a total reflective layer made of a multilayer film and a reflective layer made of a metal material such as Ag that provides high reflectance. The reflective member 43 is formed by sequentially depositing the multilayer film and the reflective layer on the flattening film 45 by deposition, sputtering, or the like. In the present embodiment, the material of the planarization film 45 is, for example, the same material (SiO2) as that of the surface layer of the total reflection layer of the multilayer film located on the phosphor layer 42 side of the reflection member 43. This improves the adhesion between the planarization film 45 and the reflection member 43. Moreover, since the surface of the phosphor layer 42 is made substantially flat by the planarizing film 45 as described above, the multilayer film and the reflective layer constituting the reflective member 43 can be uniformly formed on the second surface 42b of the phosphor layer 42. Furthermore, since the adhesion between the second surface 42b of the phosphor layer 42 and the bonding layer 50 is increased, the bonding strength of the bonding layer 50 can be further improved.

[0051] In this way, the reflective member 43 reflects a portion of the fluorescence YL generated in the phosphor layer 42 and heading toward the substrate 41 toward the first surface 42a, thereby enabling the fluorescence YL to be efficiently extracted to the outside of the phosphor layer 42.

[0052] The bonding layer 50 has a first metal layer 51 and a second metal layer 52. The first metal layer 51 is a metal layer that faces the substrate 41. The second metal layer 52 is a metal layer that is disposed between the first metal layer 51 and the phosphor layer 42.

[0053] The bonding layer 50 has a size sufficient to cover the entire second surface 42b of the phosphor layer 42. In the present embodiment, in a planar view, the outer periphery of the bonding layer 50 coincides with the outer periphery of the phosphor layer 42. Therefore, the bonding layer 50 is bonded to the peripheral edge 42b1 of the second surface 42b of the phosphor layer 42.

[0054] Here, consider a case where the size of the bonding layer 50 is slightly smaller than the second surface 42b of the phosphor layer 42, and the periphery 42b1 of the second surface 42b is exposed from the bonding layer 50. When the periphery 42b1 of the second surface 42b is exposed from the bonding layer 50, a problem occurs in that the bonding layer 50 becomes easily peeled off from the periphery 42b1 of the second surface 42b. In addition, when an external force is applied to the periphery 42b1 of the second surface 42b for some reason, defects such as chipping or cracking may occur in the periphery 42b1.

[0055] In contrast, since the bonding layer 50 of the present embodiment is bonded to the peripheral edge 42b1 of the second surface 42b of the phosphor layer 42 as described above, it is possible to suppress the occurrence of defects such as peeling of the bonding layer 50 and chipping or cracking of the peripheral edge 42b1. Therefore, the bonding layer 50 of the present embodiment can further improve the bonding reliability between the substrate 41 and the phosphor layer 42.

[0056] The first metal layer 51 is provided on the surface 41a of the substrate 41. The second metal layer 52 is disposed in a recess 53 provided in the first metal layer 51, and is in contact with the second surface 42b of the phosphor layer 42. The first metal layer 51 is in contact with the second surface 42b of the phosphor layer 42 in a portion other than the recess 53. In other words, the first metal layer 51 and the second metal layer 52 are in contact with the second surface 42b of the phosphor layer 42.

[0057] The first metal layer 51 is formed by sintering a first metal material containing at least one of Ag, Au, and Cu. The second metal layer 52 is formed by sintering a second metal material containing at least one of Ag, Au, and Cu. In other words, the first metal layer 51 contains at least one of Ag, Au, and Cu, and the second metal layer 52 contains at least one of Ag, Au, and Cu.

[0058] FIG. 4 is an image showing the main configuration of the bonding layer 50. 4, the first metal layer 51 includes a plurality of pores 51a, and the second metal layer 52 includes a plurality of pores 52a. Here, the ratio of voids caused by pores 51a to the entire volume of the first metal layer 51 is referred to as the "porosity of the first metal layer 51," and the ratio of voids caused by pores 52a to the entire volume of the second metal layer 52 is referred to as the "porosity of the second metal layer 52."

[0059] In the bonding layer 55 of the present embodiment, the porosity of the first metal layer 51 is higher than the porosity of the second metal layer 52. It is preferable that the porosity of the first metal layer 51 is not less than 30% and less than 40%, and the porosity of the second metal layer 52 is not less than 10% and less than 30%.

[0060] The first metal layer 51 has a higher porosity than the second metal layer 52, and therefore has a relatively low Young's modulus and is easily deformed. Therefore, in the bonding layer 55, the first metal layer 51 can function as a stress relaxation layer that relieves thermal stress caused by the difference in thermal expansion coefficient between the substrate 41 and the phosphor layer 42. Therefore, the bonding layer 55 can suppress the occurrence of defects such as peeling or damage of the phosphor layer 42 due to thermal stress by the first metal layer 51.

[0061] In this embodiment, the second metal layer 52 is disposed in the recess 53 of the first metal layer 51. Therefore, the first metal layer 51 is disposed so as to surround the periphery of the second metal layer 52. In this embodiment, in a state in which the bonding layer 50 is viewed from above, the first metal layer 51 surrounds the entire periphery of the second metal layer 52. Note that the shape of the first metal layer 51 in a state in which it is viewed from above may be any of a rectangular shape, a circular shape, and an elliptical shape. According to this configuration, the first metal layer 51 is disposed so as to surround the second metal layer 52 within the bonding surface of the bonding layer 50, so that the stress relaxation function of the first metal layer 51 can be generated in a well-balanced manner within the bonding surface. This can further enhance the effect of suppressing peeling or damage of the phosphor layer 42.

[0062] On the other hand, the second metal layer 52 has a lower porosity than the first metal layer 51 and therefore has a relatively high thermal conductivity, so that the heat dissipation property of the phosphor layer 42 can be improved. In this embodiment, the second metal layer 52 is disposed in correspondence with an incident region AR of the excitation light BLs in the phosphor layer 42. That is, the second metal layer 52 is disposed in a region overlapping at least a portion of the incident region AR when the first surface 42a of the phosphor layer 42 is viewed from the normal direction. In this embodiment, the second metal layer 52 is disposed in a region overlapping with the entire incident region AR.

[0063] The phosphor layer 42 generates heat when the fluorescence YL is generated, and the incident region AR usually has the highest temperature. According to the bonding layer 55 of the present embodiment, the second metal layer 52 having high thermal conductivity is disposed in an area of ​​the phosphor layer 42 corresponding to the incident region AR, which has the highest temperature, so that the heat of the phosphor layer 42 can be efficiently released.

[0064] The second metal layer 52 has a higher Young's modulus and is less likely to deform than the first metal layer 51. Therefore, the bonding layer 55 can improve the bonding strength between the substrate 41 and the phosphor layer 42 by bonding them with the first metal layer 51.

[0065] In addition, in the bonding layer 50 of this embodiment, since the first metal layer 51 and the second metal layer 52 contact the second surface 42b of the phosphor layer 42, the stress relief function of the first metal layer 51 and the cooling efficiency improvement function of the second metal layer 52 can be efficiently generated within the bonding surface.

[0066] Here, a region in the bonding layer 50 where the first metal layer 51 and the second metal layer 52 overlap in the incident direction of the excitation light BLs to the phosphor layer 42 is defined as a first region A. That is, the bonding layer 50 of the present embodiment includes the first region A where the first metal layer 51 and the second metal layer 52 overlap in the incident direction of the excitation light BLs to the phosphor layer 42.

[0067] Here, since the second metal layer 52 has a lower porosity and a denser structure than the first metal layer 51, the volume shrinkage rate is large when the material is sintered, and if the thickness is too large, cracks may occur. On the other hand, the stress relaxation function of the first metal layer 51 increases in proportion to its thickness.

[0068] 3, in the bonding layer 50 of the present embodiment, the thickness D1 of the first metal layer 51 along the incident direction in the first region A is greater than the thickness D2 of the second metal layer 52 along the incident direction. With this configuration, the stress relaxation function of the first metal layer 51 is enhanced while cracks during sintering of the second metal layer 52 are suppressed, thereby further improving the reliability of the bonding layer 50.

[0069] Next, a method for manufacturing the wavelength converter 40 of this embodiment will be described. The manufacturing method of the wavelength conversion device 40 of this embodiment includes a first step of arranging a first metal material on the substrate 41, a second step of sintering a second metal material having a smaller particle size than the first metal material arranged on the phosphor layer 42 to form a second metal layer 52, and a third step of bonding the first metal layer 51 formed by sintering the first metal material to the second metal layer 52 to generate a bonding layer 55.

[0070] Each step will be described below. Note that Figures 5A to 5C are diagrams each showing a part of the manufacturing process of the wavelength converter 40. In the first step, the first metal layer 51 is disposed on the surface 41a of the substrate 41. As the first metal material 51A, a paste-like material containing particles of at least one of Ag, Au, and Cu was used.

[0071] 5A, in the second step, a second metal material 52A is disposed on the second surface 42b of the phosphor layer 42. As the second metal material 52A, a paste-like material containing particles of at least one of Ag, Au, and Cu, the particles having an average particle size smaller than that of the first metal material 51A, is used.

[0072] In this embodiment, the phosphor layer 42 is formed, for example, by dividing a phosphor wafer into individual pieces using a dicing blade. A planarization film 45 and a reflective member 43 are formed in advance on the second surface 42b of the phosphor layer 42. Then, as shown in FIG. 5A, the second metal material 52A is sintered by applying heat H1 to the second metal material 52A to form the second metal layer 52. The second metal layer 52 is formed by sintering the second metal material 52A, which has a smaller particle size than the first metal material 51A, as described above, and therefore can have a smaller porosity than the first metal layer 51.

[0073] In addition, the second metal material 52A arranged in a predetermined area on the phosphor wafer may be sintered to form the second metal layer 52, and then the phosphor wafer may be diced into individual pieces of a predetermined size to produce the phosphor layer 42 having the second metal layer 52 formed thereon.

[0074] Next, in the third step, the first metal material 51A is sintered to form the first metal layer 51, and the first metal layer 51 and the second metal layer 52 are joined to generate the joining layer 50. In the case of this embodiment, in the third step, as shown in Fig. 5B, the first metal material 51A is sintered in a state in which the second metal layer 52 is pressed against the first metal material 51A. Note that, in this embodiment, the sintering temperature of the first metal material 51A and the sintering temperature of the second metal material 52A are preferably set to the same temperature.

[0075] 5C, a recess 53 is formed in the first metal layer 51 by pressing the second metal layer 52, and a structure can be formed in which the second metal layer 52 is disposed in the recess 53. In this manner, the wavelength converter 40 of the present embodiment shown in FIG. 3 is manufactured.

[0076] In the manufacturing method of the wavelength conversion device 40 of this embodiment, the porosity of the first metal layer 51 and the second metal layer 52 is adjusted by varying the particle size of the first metal material 51A and the second metal material 52A, but it is also possible to use another manufacturing method in which the porosity of the first metal layer 51 and the second metal layer 52 is adjusted by varying the sintering temperature of the first metal material 51A and the second metal material 52A.

[0077] Another method for manufacturing such a wavelength conversion device 40 includes a first step of arranging a first metal material on a substrate 41, a second step of sintering a second metal material arranged on the phosphor layer 42 to form a second metal layer 52, and a third step of joining the first metal layer 51 and the second metal layer 52 formed by sintering the first metal material at a sintering temperature lower than that of the second metal material to generate a bonding layer 50.

[0078] In the third step of the present manufacturing method, since the sintering temperature of the first metal material is lower than that of the second metal material, the degree of melting of the surface of each particle of the first metal material is suppressed more than the degree of melting of the surface of each particle of the second metal material. Therefore, the gap between each particle of the first metal layer is larger than that of the second metal layer, and as a result, the porosity of the first metal layer can be made higher than that of the second metal layer. Therefore, in the present manufacturing method, by adjusting the sintering temperature of the first metal material and the second metal material, it is possible to manufacture a wavelength conversion device 40 including a bonding layer 50 having a first metal layer 51 and a second metal layer 52 having different porosities. In the present manufacturing method, it is preferable to use materials having the same particle size for the first metal material and the second metal material, but the particle size of the first metal material and the second metal material may be different from each other by appropriately adjusting the sintering temperature.

[0079] Thus, the wavelength converter 40 of the present embodiment includes a phosphor layer 42 having a first surface 42a on which excitation light BLs is incident and a second surface 42b opposite to the first surface 42a, and converts the incident excitation light BLs, a substrate 41 disposed on the second surface 42b side of the phosphor layer 42, and a bonding layer 50 bonding the substrate 41 and the phosphor layer 42. The bonding layer 50 includes a first metal layer 51 facing the substrate 41 and a second metal layer 52 disposed between the first metal layer 51 and the phosphor layer 42, and the porosity of the first metal layer 51 is higher than the porosity of the second metal layer 52.

[0080] According to the wavelength converter 40 of the present embodiment, by providing the bonding layer 50 having the first metal layer 51 functioning as a stress relaxation layer and the second metal layer 52 contributing to improving the bonding strength, it is possible to increase the bonding strength between the phosphor layer 42 and the substrate 41 while suppressing peeling or damage of the phosphor layer 42 due to thermal stress. Furthermore, in the wavelength converter 40 of the present embodiment, the phosphor layer 42 and the substrate 41 are bonded together by the bonding layer 55 including the second metal layer 52 having excellent thermal conductivity, so that the phosphor layer 42 can be efficiently cooled to increase the fluorescence conversion efficiency. Therefore, the wavelength converter 40 of the present embodiment can achieve both improved bonding strength of the phosphor layer 42 and improved cooling efficiency.

[0081] Furthermore, according to the manufacturing method of the wavelength converter 40 of the present embodiment, it is possible to manufacture a wavelength converter 40 including a bonding layer 50 having a first metal layer 51 and a second metal layer 52 with different porosities by adjusting the particle sizes of the first metal material 51A and the second metal material 52A. Thus, it is possible to manufacture a wavelength converter 40 that achieves both improved bonding strength and improved cooling efficiency of the phosphor layer 42.

[0082] Furthermore, the light source device 2A including this wavelength conversion device 40 can realize a highly reliable light source device that generates bright fluorescence YL by suppressing peeling of the phosphor layer 42 while increasing the cooling efficiency of the phosphor layer 42. Furthermore, according to the projector 1 of this embodiment, since the projector 1 is provided with the light source device 2A, the projector 1 can form a high-luminance image.

[0083] Second embodiment Next, a wavelength conversion device according to a second embodiment will be described. The same reference numerals are used to designate the same components as those in the above embodiment, and detailed descriptions thereof will be omitted.

[0084] FIG. 6 is a cross-sectional view showing a configuration of a main part of a wavelength converter 140 of this embodiment. As shown in FIG. 6, a wavelength converter 140 of this embodiment includes a substrate 41, a phosphor layer 42, a reflecting member 43, and a bonding layer 150. The substrate 41 is a substrate having a phosphor layer 42 and a bonding layer 150. The bonding layer 150 is a bonding layer.

[0085] The bonding layer 150 of this embodiment has a first metal layer 151 and a second metal layer 152. In this embodiment, the second metal layer 152 is laminated on a surface 151a of the first metal layer 151, which is a flat surface. In a planar view, the first metal layer 151 and the second metal layer 152 have the same shape as the phosphor layer 42. That is, in the bonding layer 150 of this embodiment, the back surface 152b of the second metal layer 152 and the surface 151a of the first metal layer 151 have the same shape, and the surface 152a of the second metal layer 152 and the second surface 42b of the phosphor layer 42 have the same shape.

[0086] According to the wavelength converter 140 of the present embodiment, since it includes the bonding layer 150 having the first metal layer 151 functioning as a stress relaxation layer and the second metal layer 152 contributing to improving the bonding strength, it is possible to improve both the bonding strength and the cooling efficiency of the phosphor layer 42. Furthermore, since the wavelength converter 240 of the present embodiment includes the bonding layer 150 having a structure in which the first metal layer 151 and the second metal layer 152 are laminated, the manufacturing process of the bonding layer 150 can be simplified compared to the configuration of the first embodiment.

[0087] Third embodiment Next, a wavelength conversion device according to a third embodiment will be described. The same reference numerals are used to designate the same components as those in the above-described embodiment, and detailed descriptions thereof will be omitted.

[0088] FIG. 7 is a cross-sectional view showing a configuration of a main part of a wavelength converter 240 of this embodiment. As shown in FIG. 7, a wavelength converter 240 of this embodiment includes a substrate 41, a phosphor layer 42, a reflecting member 43, and a bonding layer 250. The substrate 41 is a substrate having a phosphor layer 42 and a bonding layer 250. The bonding layer 250 is a bonding layer.

[0089] The bonding layer 250 of the present embodiment has a first metal layer 251 and a second metal layer 252. The second metal layer 252 has the same size as the phosphor layer 42, similar to the wavelength conversion device 140 of the second embodiment. On the other hand, the first metal layer 251 includes a base portion 251a and a convex portion 251b.

[0090] The base portion 251a faces the substrate 41 and is a portion sandwiched between the substrate 41 and the second metal layer 252. The base portion 251a protrudes outward from the second metal layer 252. The convex portion 251b protrudes toward the phosphor layer 42 from the portion of the base portion 251a that protrudes outward from the second metal layer 252 and faces the third surface 42c of the phosphor layer 42. The third surface 42c of the phosphor layer 42 is a surface that intersects with the first surface 42a and the second surface 42b, and corresponds to a side surface of the phosphor layer 42. In other words, the convex portion 251b in this embodiment corresponds to the "facing portion" in the claims. In this embodiment, a part of the convex portion 251b of the first metal layer 251 is in contact with a third surface c, which is a side surface of the phosphor layer .

[0091] According to the wavelength conversion device 240 of the present embodiment, since the bonding layer 250 having the first metal layer 251 functioning as a stress relaxation layer and the second metal layer 252 contributing to the improvement of the bonding strength is provided, it is possible to improve both the bonding strength and the cooling efficiency of the phosphor layer 42. In addition, since the third surface 42c, which is the side surface of the phosphor layer 42, is covered by the convex portion 251b of the first metal layer 251, even if an external force is applied due to some factor, chipping or damage of the third surface 42c, which is the side surface of the phosphor layer 42, can be suppressed. Therefore, the durability of the phosphor layer 42 can be improved. In addition, since a part of the convex portion 251b contacts the third surface 42c of the phosphor layer 42, the heat of the phosphor layer 42 can be released to the first metal layer 251 side via the convex portion 251b. This can further improve the cooling efficiency of the phosphor layer 42.

[0092] 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.

[0093] In the wavelength conversion device 40 of the first embodiment, the second metal layer 52 is disposed so as to surround the entire periphery of the first metal layer 51 in a planar view, but the positional relationship between the second metal layer 52 and the first metal layer 51 is not limited to this. For example, in a planar view, a part of the side surface of the first metal layer 51 may be exposed from the second metal layer 52. In other words, in a planar view, a part of the side surface of the first metal layer 51 may be flush with the side surface of the second metal layer 52, or a part of the side surface of the first metal layer 51 may protrude from the side surface of the second metal layer 52.

[0094] In addition, in the wavelength conversion device 40 of the first embodiment, the bonding layer 50 has a size sufficient to cover the entire second surface 42b of the phosphor layer 42, and thus the bonding layer 50 is bonded to the peripheral edge 42b1 of the second surface 42b. However, the bonding layer 50 does not have to cover a portion of the second surface 42b of the phosphor layer 42. In other words, the bonding layer 50 does not have to be bonded to a portion of the peripheral edge 42b1 of the second surface 42b.

[0095] In addition, in the first and second embodiments, when viewed in a planar state, the outer periphery of the bonding layer 50, 150 coincides with the outer periphery of the phosphor layer 42, but at least a portion of the outer periphery of the bonding layer 50, 150 may extend beyond the outer periphery of the phosphor layer 42.

[0096] Furthermore, the wavelength converter according to the present invention is not limited to a fixed type, but can be applied to, for example, a rotary type wavelength converter in which a circular substrate rotates.

[0097] Furthermore, in the first embodiment, the reflecting member and the bonding layer are provided, but if the bonding layer has sufficient reflective properties, the reflecting member can be omitted.

[0098] In the first embodiment, the bonding layer has a first metal layer and a second metal layer, but the number of layers is not limited to this. For example, the bonding layer may have three or more layers. Note that the "layer" is not limited to a layer having a clear boundary between materials, and a layer in which the porosity gradually changes from the substrate to the phosphor layer can be interpreted as having multiple metal layers with different porosities.

[0099] In addition, in the above embodiment, an example in which the light source device according to the present invention is mounted on a projector is shown, but the present invention is not limited to this. The light source device according to the present invention can also be applied to lighting fixtures, automobile headlights, and the like.

[0100] The following is a summary of this disclosure. (Appendix 1) a wavelength conversion layer having a first surface onto which light is incident and a second surface opposite to the first surface, the wavelength conversion layer converting the incident light; a substrate disposed on the second surface side of the wavelength conversion layer; a bonding layer that bonds the substrate and the wavelength conversion layer, the bonding layer includes a first metal layer facing the substrate and a second metal layer disposed between the first metal layer and the wavelength conversion layer; The porosity of the first metal layer is higher than the porosity of the second metal layer. Wavelength conversion device.

[0101] According to the wavelength conversion device having this configuration, by providing a bonding layer having a first metal layer with high porosity that functions as a stress relaxation layer and a second metal layer with low porosity that contributes to improving the bonding strength, it is possible to increase the bonding strength between the wavelength conversion layer and the substrate while suppressing peeling or damage of the wavelength conversion layer due to thermal stress. In addition, since the wavelength conversion layer and the substrate are bonded by the second metal layer with excellent thermal conductivity, it is possible to efficiently cool the wavelength conversion layer and increase the wavelength conversion efficiency. Therefore, with this configuration, it is possible to improve both the bonding strength of the wavelength conversion layer and the cooling efficiency.

[0102] (Appendix 2) the second metal layer is disposed in correspondence with an incident area of ​​the wavelength conversion layer, 2. A wavelength conversion device according to claim 1.

[0103] According to this configuration, by disposing the second metal layer having excellent thermal conductivity in a region of the wavelength conversion layer corresponding to the incident region which has the highest temperature, the wavelength conversion layer can be efficiently cooled.

[0104] (Appendix 3) The first metal layer is disposed so as to surround the second metal layer. 3. A wavelength conversion device as described in appendix 2.

[0105] According to this configuration, the first metal layer is disposed so as to surround the second metal layer within the bonding surface of the bonding layer, so that the stress relaxation function of the first metal layer can be generated in a well-balanced manner within the bonding surface, thereby further enhancing the effect of suppressing peeling or damage of the fluorescent wavelength conversion layer.

[0106] (Appendix 4) the second metal layer is disposed in a recess provided in the first metal layer; the first metal layer and the second metal layer are in contact with the wavelength conversion layer. 4. A wavelength conversion device according to claim 1,

[0107] With this configuration, the first metal layer and the second metal layer are in contact with the wavelength conversion layer, so that the stress relief function of the first metal layer and the cooling efficiency improvement function of the second metal layer can be efficiently generated within the bonding surface.

[0108] (Appendix 5) The porosity of the first metal layer is 30% or more and less than 40%, The porosity of the second metal layer is 10% or more and less than 30%. 5. A wavelength conversion device according to claim 1,

[0109] This configuration makes it possible to realize a bonding layer in which the porosity of the first metal layer is higher than the porosity of the second metal layer.

[0110] (Appendix 6) the first metal layer includes at least one of Ag, Au, and Cu; The second metal layer includes at least one of Ag, Au, and Cu. 6. A wavelength conversion device according to any one of claims 1 to 5.

[0111] This configuration makes it possible to realize a bonding layer having a first metal layer and a second metal layer with different porosities.

[0112] (Appendix 7) The bonding layer is bonded to a peripheral edge of the second surface of the wavelength conversion layer. 7. A wavelength conversion device according to any one of claims 1 to 6.

[0113] This configuration can suppress the occurrence of defects such as peeling of the bonding layer and chipping or cracking of the periphery, thereby further improving the bonding reliability between the substrate and the wavelength conversion layer.

[0114] (Appendix 8) the bonding layer includes a first region where the first metal layer and the second metal layer overlap in an incident direction of the light to the wavelength conversion layer, a thickness of the first metal layer along the incident direction in the first region is greater than a thickness of the second metal layer along the incident direction in the first region; 8. A wavelength conversion device according to any one of claims 1 to 7.

[0115] According to this configuration, the stress relaxation function of the first metal layer is improved while cracks occurring during sintering of the second metal layer are suppressed, thereby making it possible to further improve the reliability of the bonding layer.

[0116] (Appendix 9) the first metal layer includes an opposing portion facing a third surface intersecting the first surface and the second surface of the wavelength conversion layer, a portion of the facing portion of the first metal layer contacts the third surface of the wavelength conversion layer; 9. A wavelength conversion device according to any one of claims 1 to 8.

[0117] According to this configuration, the third surface of the wavelength conversion layer is covered by the facing portion of the first metal layer, so that even if an external force is applied due to some factor, chipping or damage to the third surface of the wavelength conversion layer can be suppressed. This improves the durability of the wavelength conversion layer. In addition, because part of the facing portion contacts the third surface of the wavelength conversion layer, heat from the wavelength conversion layer can be released to the first metal layer side through the facing portion. This improves the cooling efficiency of the wavelength conversion layer.

[0118] (Appendix 10) The wavelength conversion layer includes a planarization film that planarizes the second surface. 4. A wavelength conversion device according to claim 1,

[0119] According to this configuration, the flatness of the surface of the wavelength conversion layer can be improved by the planarizing film, and therefore the adhesion between the wavelength conversion layer and the bonding layer can be improved, thereby further improving the bonding strength of the bonding layer.

[0120] (Appendix 11) A wavelength conversion device according to any one of claims 1 to 10, A light source that emits the light to the wavelength conversion device. Light source device.

[0121] According to the light source device having this configuration, it is possible to provide a highly reliable light source device that generates bright light by suppressing peeling of the wavelength conversion layer while increasing the cooling efficiency of the wavelength conversion layer.

[0122] (Appendix 12) A light source device according to claim 11; a light modulation device that changes the amount of light emitted from the light source device based on image information; a projection optical system that projects the light emitted from the light modulation device. projector.

[0123] According to the projector having this configuration, since the projector includes the light source device, the projector can form a high brightness image.

[0124] (Appendix 13) 1. A method for manufacturing a wavelength conversion device comprising: a wavelength conversion layer; a substrate; and a bonding layer bonding the substrate and the wavelength conversion layer, the bonding layer having a first metal layer facing the substrate; and a second metal layer having a higher porosity than the first metal layer and disposed between the first metal layer and the wavelength conversion layer, the method comprising: a first step of disposing a first metallic material on the substrate; a second step of sintering a second metal material having a smaller particle size than the first metal material disposed on the wavelength conversion layer to form the second metal layer; and a third step of bonding the first metal layer formed by sintering the first metal material to the second metal layer to generate the bonding layer. A method for manufacturing a wavelength conversion device.

[0125] According to the method for manufacturing a wavelength conversion device having this configuration, it is possible to manufacture a wavelength conversion device having a bonding layer having a first metal layer and a second metal layer with different porosities by adjusting the particle diameters of the first metal material and the second metal material, thereby providing a wavelength conversion device that achieves both improved bonding strength and cooling efficiency of the wavelength conversion layer.

[0126] (Appendix 14) 1. A method for manufacturing a wavelength conversion device comprising: a wavelength conversion layer; a substrate; and a bonding layer bonding the substrate and the wavelength conversion layer, the bonding layer having a first metal layer facing the substrate; and a second metal layer having a higher porosity than the first metal layer and disposed between the first metal layer and the wavelength conversion layer, the method comprising: A first step of disposing a first metal material on the substrate; a second step of sintering the second metallic material disposed on the wavelength conversion layer to form the second metallic layer; and a third step of bonding the first metal layer formed by sintering the first metal material at a sintering temperature lower than that of the second metal material to the second metal layer to generate the bonding layer. A method for manufacturing a wavelength conversion device.

[0127] According to the method for manufacturing a wavelength converter having this configuration, by adjusting the sintering temperatures of the first metal material and the second metal material, a wavelength converter having a bonding layer including a first metal layer and a second metal layer having different porosities can be manufactured, thereby providing a wavelength converter that achieves both improved bonding strength of the wavelength conversion layer and improved cooling efficiency.

[0128] (Appendix 15) In the first step, metal particles containing at least one of Ag, Au, and Cu are used as the first metal material, and in the second step, metal particles containing at least one of Ag, Au, and Cu are used as the second metal material. 15. A method for producing a wavelength converter according to claim 13 or 14.

[0129] According to this configuration, the bonding layer having the first metal layer and the second metal layer with different porosities can be manufactured by sintering the first metal material and the second metal material.

[0130] (Appendix 16) The third step includes sintering the first metal material while pressing the second metal layer against the first metal material. 16. A method for manufacturing a wavelength converter according to any one of claims 13 to 15.

[0131] According to this configuration, it is possible to manufacture a structure in which the second metal layer is disposed in a recess formed in the first metal layer. [Explanation of symbols]

[0132] 1...projector, 2A...light source device, 4B, 4G, 4R...light modulation device, 6...projection optical system, 40, 140, 240...wavelength conversion device, 40...phosphor layer (wavelength conversion layer), 41...substrate, 42a...first surface, 42b...second surface, 42c...third surface, 45...planarization film, 50, 55, 150, 250...bonding layer, 51, 151, 251...first metal layer, 51A...first metal material, 52, 152, 252...second metal layer, 52A...second metal material, 53...recess, 42b1...periphery, 251b...convex portion (opposing portion), A...first region, AR...incident region, D1, D2...thickness.

Claims

1. A wavelength conversion layer having a first surface to which light is incident and a second surface opposite to the first surface, which converts the incident light, A substrate disposed on the second surface side of the wavelength conversion layer, The system comprises a bonding layer that bonds the substrate and the wavelength conversion layer, The bonding layer comprises a first metal layer facing the substrate and a second metal layer disposed between the first metal layer and the wavelength conversion layer. The porosity of the first metal layer is higher than that of the second metal layer. Wavelength conversion device.

2. The second metal layer is arranged in a manner corresponding to the incident region of the light in the wavelength conversion layer. The wavelength conversion device according to claim 1.

3. The first metal layer is arranged so as to surround the second metal layer. The wavelength conversion device according to claim 2.

4. The second metal layer is placed in a recess provided in the first metal layer. The first metal layer and the second metal layer are in contact with the wavelength conversion layer. A wavelength conversion device according to any one of claims 1 to 3.

5. The porosity of the first metal layer is 30% or more and less than 40%. The porosity of the second metal layer is 10% or more and less than 30%. A wavelength conversion device according to any one of claims 1 to 3.

6. The first metal layer comprises at least one of Ag, Au, and Cu. The second metal layer comprises at least one of Ag, Au, and Cu. A wavelength conversion device according to any one of claims 1 to 3.

7. The bonding layer is bonded to the periphery of the second surface of the wavelength conversion layer. A wavelength conversion device according to any one of claims 1 to 3.

8. The bonding layer includes a first region in which the first metal layer and the second metal layer overlap in the direction of incidence of the light to the wavelength conversion layer. The thickness of the first metal layer along the incident direction in the first region is greater than the thickness of the second metal layer along the incident direction in the first region. A wavelength conversion device according to any one of claims 1 to 3.

9. The first metal layer includes a portion facing a third surface that intersects the first and second surfaces in the wavelength conversion layer, A portion of the opposing portion of the first metal layer contacts the third surface of the wavelength conversion layer. A wavelength conversion device according to any one of claims 1 to 3.

10. The wavelength conversion layer includes a planarizing film that flattens the second surface. A wavelength conversion device according to any one of claims 1 to 3.

11. A wavelength conversion device according to any one of claims 1 to 3, The wavelength conversion device comprises a light source that emits the light, Light source device.

12. The light source device according to claim 11, A light modulation device that modulates light emitted from the aforementioned light source device based on image information, The system comprises a projection optical system that projects light emitted from the aforementioned optical modulation device, projector.

13. A method for manufacturing a wavelength conversion apparatus, comprising a wavelength conversion layer, a substrate, and a bonding layer for bonding the substrate and the wavelength conversion layer, wherein the bonding layer comprises a first metal layer facing the substrate and a second metal layer having a higher porosity than the first metal layer and being disposed between the first metal layer and the wavelength conversion layer, A first step of placing a first metal material on the substrate, A second step is to form the second metal layer by sintering a second metal material with a smaller particle size than the first metal material arranged in the wavelength conversion layer, The method comprises a third step of forming a bonded layer by joining a first metal layer formed by sintering the first metal material with a second metal layer, A method for manufacturing a wavelength conversion device.

14. A method for manufacturing a wavelength conversion apparatus, comprising a wavelength conversion layer, a substrate, and a bonding layer for bonding the substrate and the wavelength conversion layer, wherein the bonding layer comprises a first metal layer facing the substrate and a second metal layer having a higher porosity than the first metal layer and being disposed between the first metal layer and the wavelength conversion layer, A first step of placing a first metal material on the substrate, A second step involves sintering the second metal material placed in the wavelength conversion layer to form the second metal layer, The method comprises a third step of forming a bonded layer by joining the first metal layer and the second metal layer, which are formed by sintering the first metal material at a sintering temperature lower than that of the second metal material. A method for manufacturing a wavelength conversion device.

15. In the first step, metal particles containing at least one of Ag, Au, and Cu are used as the first metal material. In the second step, metal particles containing at least one of Ag, Au, and Cu are used as the second metal material. A method for manufacturing a wavelength conversion device according to claim 13 or claim 14.

16. The third step involves sintering the first metal material while pressing the second metal layer against the first metal material. A method for manufacturing a wavelength conversion device according to claim 13 or claim 14.

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