Wavelength conversion device, light source device, and projector

Abstract

The present invention provides a wavelength conversion device, a light source device, and a projector capable of suppressing the occurrence of delamination between the wavelength conversion layer and the substrate. [Solution] The wavelength conversion device comprises a substrate having a first surface, a wavelength conversion layer positioned on the incident side of the substrate for first light in a first wavelength band and converting the incident first light into second light in a second wavelength band different from the first wavelength band, a reflective film positioned between the wavelength conversion layer and the first surface and reflecting light incident from the wavelength conversion layer, and a bonding portion positioned between the reflective film and the first surface and bonding the reflective film and the substrate, wherein the bonding portion contains silver and a migration-inhibiting substance that suppresses the movement of silver.

Description

Technical Field

[0001] The present disclosure relates to a wavelength conversion device, a light source device, and a projector.

Background Art

[0002] Conventionally, as a light source device that can be used in a projector, a fluorescent light source device including a laser diode and a fluorescent light emitting member is known (see, for example, Patent Document 1). The fluorescent light source device described in Patent Document 1 converts light in the blue region emitted from a laser diode into fluorescence in the green region by a fluorescent light emitting member composed of a phosphor. The fluorescent light emitting member is formed by bonding a phosphor plate on a substrate surface via a bonding metal layer. Specifically, a metal film formed of a gold film on the substrate surface and a nickel / platinum / gold film or nickel / gold film formed on the back side of the phosphor plate are bonded by a bonding metal layer. Examples of the bonding metal layer include those containing silver, such as a silver sintered material or silver paste.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in order to increase the bonding strength between a substrate and a light reflection layer formed on a phosphor plate, a technique of disposing an auxiliary bonding layer containing the same metal as the bonding metal layer may be adopted. However, when a temperature difference in the phosphor plate becomes large due to the incidence of excitation light, stress is generated. Such stress may cause partial peeling of the phosphor plate and the light reflection film at the bonding metal layer. In this case, the heat transfer efficiency from the phosphor plate to the substrate may decrease, and the light utilization efficiency of the fluorescent light emitting member may decrease. Therefore, there has been a demand for a configuration that can suppress the occurrence of delamination between the phosphor plate and the substrate. [Means for solving the problem]

[0005] A wavelength conversion device according to a first aspect of the present disclosure comprises: a substrate having a first surface; a wavelength conversion layer disposed on the incident side of the substrate for first light in a first wavelength band, which converts the incident first light into second light in a second wavelength band different from the first wavelength band; a reflective film disposed between the wavelength conversion layer and the first surface, which reflects light incident from the wavelength conversion layer; and a joint disposed between the reflective film and the first surface, which joins the reflective film and the substrate, wherein the joint contains silver and a migration-inhibiting substance that suppresses the movement of silver.

[0006] A light source device according to a second aspect of this disclosure comprises a light source that emits the first light, and a wavelength conversion device according to the first aspect, to which the first light emitted from the light source is incident.

[0007] A projector according to a third aspect of this disclosure comprises a light source device according to the third aspect, an optical modulator for modulating light emitted from the light source device, and a projection optical device for projecting the light modulated by the optical modulator. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram showing the configuration of the projector in the first embodiment. [Figure 2] A schematic diagram showing the configuration of the light source device in the first embodiment. [Figure 3] A cross-sectional view showing the wavelength conversion device in the first embodiment. [Figure 4] A cross-sectional view showing the wavelength conversion device in the second embodiment. [Figure 5] A cross-sectional view showing the wavelength conversion device in the third embodiment. [Figure 6] A cross-sectional view showing the wavelength conversion device in the fourth embodiment. [Modes for carrying out the invention]

[0009] [First Embodiment] The first embodiment of this disclosure will be described below with reference to the drawings. [Projector Configuration Overview] Figure 1 is a schematic diagram showing the configuration of the projector 1 according to this embodiment. The projector 1 according to this embodiment projects image light corresponding to image information. As shown in Figure 1, the projector 1 comprises an outer casing 2 and an image projection device 3 housed in the outer casing 2. In addition, although not shown, the projector 1 comprises a control device for controlling the operation of the projector 1, a power supply device for supplying power to the electronic components of the projector 1, and a cooling device for cooling the parts of the projector 1 that need to be cooled.

[0010] [Configuration of the image projection device] The image projection device 3 forms image light according to the input image information and projects the formed image light. The image projection device 3 comprises a light source device 4, an image light generation device 30, and a projection optical device 36. The light source device 4 emits illumination light into the homogenization optical system 31 of the image light generation device 30. The configuration of the light source device 4 will be described in detail later.

[0011] The image light generation device 30 generates image light from illumination light emitted from the light source device 4. The image light generation device 30 includes a homogenization optical system 31, a color separation optical system 32, a relay optical system 33, a light modulation device 34, and an optical component housing 35. The homogenization optical system 31 homogenizes the illumination light emitted from the light source device 4. The homogenized illumination light passes through the color separation optical system 32 and the relay optical system 33 to illuminate the modulation region of the light modulation element 343, which will be described later. The homogenization optical system 31 includes two lens arrays 311 and 312, a polarization conversion element 313, and a superimposed lens 314. The color separation optical system 32 separates the illumination light incident from the homogenization optical system 31 into red, green, and blue light. The color separation optical system 32 comprises two dichroic mirrors 321 and 323, a reflective mirror 322 that reflects the blue light separated by the dichroic mirror 321, a lens 324 positioned between the dichroic mirror 321 and the reflective mirror 322, and a lens 325 positioned between the dichroic mirrors 321 and 323.

[0012] The relay optical system 33 is located in the optical path of red light, which is longer than the optical paths of other colored light, in order to suppress the loss of red light. The relay optical system 33 comprises an incident lens 331, a relay lens 333, and reflective mirrors 332 and 334. In this embodiment, red light is directed to the relay optical system 33. However, this is not the only option; for example, the colored light with a longer optical path than other colored light may be designated as blue light, and the blue light may be directed to the relay optical system 33.

[0013] The optical modulator 34 modulates the incident red, green, and blue light, and combines the modulated light to form an image. The optical modulator 34 includes three field lenses 341 provided according to the color of the incident light, three incident polarizers 342, three optical modulation elements 343, three exit polarizers 344, and one color synthesis optical system 345.

[0014] The optical modulation element 343 modulates the light from the light source device 4 to form image light. Specifically, the optical modulation element 343 modulates the color light incident from the incident polarizer 342 according to the image signal and emits the modulated color light. The three optical modulation elements 343 include an optical modulation element 343R that modulates red light, an optical modulation element 343G that modulates green light, and an optical modulation element 343B that modulates blue light. A transmissive liquid crystal panel can be used as an example of an optical modulation element 343.

[0015] The color synthesis optical system 345 synthesizes three color lights modulated by the light modulation elements 343R, 343G, and 343B. The image light synthesized by the color synthesis optical system 345 is incident on the projection optical device 36. In this embodiment, the color synthesis optical system 345 is constituted by a substantially rectangular parallelepiped cross dichroic prism, but it may be constituted by a plurality of dichroic mirrors.

[0016] The housing 35 for optical components houses the above-described homogenization optical system 31, color separation optical system 32, and relay optical system 33 inside. In the image projection device 3, an optical axis Ax in design is set, and the housing 35 for optical components holds the homogenization optical system 31, color separation optical system 32, relay optical system 33, and light modulation device 34 at a predetermined position on the optical axis Ax. The light source device 4, light modulation device 34, and projection optical device 36 are arranged at predetermined positions on the optical axis Ax. The projection optical device 36 projects the image light incident from the light modulation device 34 onto a projection surface such as a screen. That is, the projection optical device 36 projects the image light formed by the light modulation device 34. The projection optical device 36 can be, for example, a combined lens including a plurality of lenses and a lens barrel that houses the plurality of lenses.

[0017] [Configuration of Light Source Device] FIG. 2 is a schematic diagram showing the configuration of the light source device 4. The light source device 4 emits illumination light WL in the +X direction toward the homogenization optical system 31. As shown in FIG. 2, the light source device 4 includes a light source 41, a diffusion transmission part 42, a light separation part 43, a first condenser 44, a wavelength conversion device 5A, a second condenser 45, a diffusion optical member 46, and a housing CA for the light source. In the following description, three mutually orthogonal directions are defined as the +X direction, +Y direction, and +Z direction. In this embodiment, the +Z direction is the direction in which the principal ray is emitted from the wavelength conversion device 5A, and the +X direction orthogonal to the +Z direction is the direction in which the illumination light WL is emitted from the light source device 4. Although not shown in the diagram, the direction opposite to the +X direction is defined as the -X direction, the direction opposite to the +Y direction is defined as the -Y direction, and the direction opposite to the +Z direction is defined as the -Z direction. The -Z direction is also the direction in which the light source 41 emits excitation light. Furthermore, the axis along the +X direction is defined as the X-axis, and the axis along the +Z direction is defined as the Z-axis.

[0018] The light source device 4 has an optical axis Ax1 along the Z axis and an optical axis Ax2 along the X axis, and optical axes Ax1 and Ax2 are orthogonal to each other. The optical components of the light source device 4 are arranged on either optical axis Ax1 or optical axis Ax2. Specifically, the light source 41, the diffuse transmission unit 42, the light separation unit 43, the first light concentrating element 44, and the wavelength conversion device 5A are arranged on the optical axis Ax1. The diffusing optical element 46, the second light-gathering element 45, and the light-separating unit 43 are arranged on the optical axis Ax2. That is, the light-separating unit 43 is positioned at the intersection of the optical axis Ax1 and the optical axis Ax2. The optical axis Ax2 is connected to the optical axis Ax of the image projection device 3 by the lens array 311 of the homogenization optical system 31.

[0019] [Light source configuration] The light source 41 emits light in the -Z direction. The light source 41 comprises a light-emitting element 411 and a substrate 412. The light-emitting element 411 emits blue light BL. The blue light BL is excitation light that excites the phosphor in the wavelength converter 5A. The light-emitting element 411 is, for example, a semiconductor laser that emits laser light with a peak wavelength of 455 nm. The substrate 412 is fixed to the inner surface of the light source housing CA with the light-emitting element 411 in support. The substrate 412 receives heat from the light-emitting element 411 and transfers the received heat to the heat dissipation member HD which is exposed to the outside of the light source housing CA.

[0020] [Structure of the diffuse transmission section] The diffuse transmission section 42 diffuses the blue light BL incident from the light source 41 and emits light with a uniform illuminance distribution. The blue light BL emitted from the diffuse transmission section 42 is incident on the light separation section 43. The diffuse transmission section 42 can be exemplified by a configuration having a hologram, a configuration in which a plurality of small lenses are arranged in a plane perpendicular to the optical axis, and a configuration in which the surface through which light passes is rough. Alternatively, instead of the diffuse transmission section 42, a homogenizer optical element having a pair of multi-lens arrays may be used in the light source device 4. On the other hand, when the diffuse transmission section 42 is used, the distance from the light source 41 to the light separation section 43 can be shortened compared to when the homogenizer optical element is used.

[0021] [Configuration of the optical separation unit] The light separation unit 43 functions as a half-mirror, allowing some of the blue light BL incident from the light source 41 through the diffuse transmission unit 42 to pass through, while reflecting the other blue light BL. Specifically, the light separation unit 43 transmits a portion of the blue light BL, the first partial light, in the -Z direction to the first light-gathering element 44, and reflects the other blue light BL, the second partial light, in the -X direction to the second light-gathering element 45. The light separation unit 43 further functions as a dichroic mirror, reflecting the fluorescent light YL incident in the +Z direction from the wavelength conversion device 5A and transmitting the blue light BL incident in the +X direction from the diffuse optical member 46.

[0022] [Configuration of the first light-gathering element] The first light-gathering element 44 focuses the first partial light that has passed through the light-separating unit 43 onto the wavelength-converting device 5A. The first light-gathering element 44 also parallelizes the fluorescent YL incident from the wavelength-converting device 5A and directs it onto the light-separating unit 43 along the +Z direction.

[0023] [Outline configuration of the wavelength conversion device] The wavelength converter 5A is a reflective type wavelength converter that converts the first light of the incident first wavelength band into second light of a second wavelength band different from the first wavelength band, and emits the second light diffused in the opposite direction to the incident direction of the first light. The second light is, for example, unpolarized fluorescent YL having a peak wavelength in the range of 500 to 700 nm, and the fluorescent YL includes green light and red light. The configuration of the wavelength converter 5A will be described in detail later. The fluorescent YL emitted from the wavelength converter 5A passes through the first light-gathering element 44 along the optical axis Ax1 and then enters the light-separating unit 43. The fluorescent YL that enters the light-separating unit 43 is reflected in the +X direction and emitted outside the light source device 4 along the optical axis Ax2.

[0024] [Configuration of the second light-gathering element] The second light-gathering element 45 focuses the second partial light incident from the light-separating unit 43 onto the diffusing optical member 46. The second light-gathering element 45 parallelizes the blue light incident from the diffusing optical member 46 and directs it onto the light-separating unit 43 along the +Z direction.

[0025] [Configuration of Diffusive Optical Components] The diffusing optical element 46 reflects and diffuses the blue light BL incident from the second light-gathering element 45 at a diffusion angle that is approximately the same as, or slightly smaller than, the diffusion angle of the fluorescent YL emitted from the wavelength conversion device 5A. In other words, the diffusing optical element 46 reflects and diffuses the incident light without converting the wavelength of the incident light. The blue light BL reflected in the +X direction by the diffusing optical element 46 passes through the second light-gathering element 45, then through the light separation unit 43 in the +X direction, and is emitted outside the light source device 4 together with the fluorescent YL. As described above, the illumination light WL emitted outside the light source device 4 is white light, which is a mixture of blue light BL and fluorescent light YL containing green and red light. The illumination light WL is emitted from the light source device 4 in the +X direction through the passage opening CA1 of the light source housing CA.

[0026] [Configuration of the light source enclosure] The light source housing CA is the housing of the light source device 4 and is one of the internal housings housed inside the outer housing 2. The light source housing CA houses the light source 41, the diffuse transmission section 42, the light separation section 43, the first light concentrating element 44, the wavelength conversion device 5A, the second light concentrating element 45, and the diffuse optical member 46. In this embodiment, the light source housing CA is a sealed housing that is less likely to allow dust to enter the interior. However, it is not limited to this, and the light source housing CA only needs to be able to house the optical components described above. The light source housing CA has a passage opening CA1. The passage opening CA1 is an opening through which the illumination light WL passes through the light source housing CA.

[0027] [Detailed configuration of the wavelength conversion device] Figure 3 shows a cross-section of the wavelength converter 5A along the XZ plane. That is, Figure 3 shows a cross-section of the wavelength converter 5A along a plane defined by the -Z direction, which is the incident direction of blue light BL to the wavelength converter 5A, and the +X direction, which is perpendicular to the -Z direction. As described above, the wavelength conversion device 5A emits fluorescent YL in the +Z direction, which is obtained by converting blue light BL incident along the -Z direction. As shown in Figure 3, the wavelength conversion device 5A has a base material 51, a junction 52A, a reflective film 55, and a wavelength conversion layer 56, as well as a heat dissipation member 57 as shown in Figure 2. In the wavelength conversion device 5A, the wavelength conversion layer 56, reflective film 55, junction 52A, base material 51, and heat dissipation member 57 are arranged in that order in the -Z direction, which is the incident direction of blue light BL. In other words, in the wavelength conversion device 5A, the heat dissipation member 57, base material 51, junction 52A, reflective film 55, and wavelength conversion layer 56 are arranged in that order in the +Z direction, which is the emission direction of fluorescent YL from the wavelength conversion device 5A.

[0028] [Composition of the base material] The substrate 51 supports the reflective film 55 and the wavelength conversion layer 56, which are bonded to the substrate 51 by the bonding portion 52A. The substrate 51 has a substrate 511 and a metal film 512. The substrate 511 supports the wavelength conversion layer 56 and also dissipates heat transferred from the wavelength conversion layer 56 to the heat dissipation member 57. The substrate 511 is a plate-like body made of either copper or a copper alloy. The copper or copper alloy content in the substrate 511 can be above a predetermined percentage, for example, 90% or more is preferred. The substrate 511 may also contain impurities.

[0029] The metal film 512 is provided on substantially the entire surface of the first surface 511A of the substrate 511 that is oriented in the +Z direction, and constitutes the first surface 51A of the substrate 51. That is, the metal film 512 constitutes the first surface 51A of the substrate 51 that is oriented in the +Y direction. The metal film 512 contains one of the precious metals silver (Ag), gold (Au), platinum (Pt), and palladium (Pd). More specifically, the metal film 512 contains particles of the precious metal. The metal film 512 has the function of increasing the bonding strength between the substrate 51 and the joint 52A, and the first surface 51A, which is made of the metal film 512, is bonded to the bonding material 54 of the joint 52A, which will be described later.

[0030] [Wavelength conversion layer configuration] Before describing the junction 52A, the wavelength conversion layer 56 and the reflective film 55 will be described. The wavelength conversion layer 56 is provided at the +Z end of the wavelength conversion device 5A where the blue light BL is incident. The wavelength conversion layer 56 is a phosphor layer containing a phosphor that is excited when the blue light BL is incident on the incident surface 561 facing the +Z direction. Examples of phosphors include a YAG:Ce phosphor containing cerium as an activator. The blue light BL is directly incident on the wavelength conversion layer 56 from the first light-gathering element 44, and the wavelength conversion layer 56 emits fluorescence YL upon the incidence of the blue light BL.

[0031] [Composition of the reflective film] The reflective film 55 is positioned on the substrate 51 side relative to the wavelength conversion layer 56. That is, the reflective film 55 is located in the -Z direction, which is opposite to the incident side of the blue light BL, relative to the wavelength conversion layer 56. Furthermore, the reflective film 55 is positioned on the opposite side of the substrate 51 from the junction 52A and in contact with the junction 52A. The reflective film 55 reflects light incident from the wavelength conversion layer 56 back to the wavelength conversion layer 56. That is, the reflective film 55 is connected to the side of the wavelength conversion layer 56 opposite to the incident side of the blue light BL. The reflective film 55 has a multilayer structure including a total reflection layer.

[0032] [Connection structure] The joint portion 52A is positioned between the first surface 51A of the base material 51 and the reflective film 55, and joins the base material 51 and the reflective film 55, and consequently joins the base material 51, the reflective film 55, and the wavelength conversion layer 56. The joint portion 52A includes a bonding film 53A and a bonding material 54.

[0033] [Composition of bonding material] The bonding material 54 is positioned on the substrate 51 side, which is opposite to the reflective film 55, relative to the bonding film 53A, and is in contact with the first surface 51A of the substrate 51. In other words, the bonding material 54 is positioned in the -Z direction relative to the bonding film 53A and is in contact with the first surface 51A. The bonding material 54 contains metal nanoparticles, and more specifically, contains nanoparticles of precious metals. In this embodiment, the bonding material 54 is composed of a sintered material containing silver nanoparticles.

[0034] [Composition of the bonding film] The bonding film 53A is positioned on the reflective film 55 side relative to the bonding material 54 and is in contact with the reflective film 55. The bonding film 53A bonds the substrate 51 and the reflective film 55 by adhering to the bonding material 54. In this embodiment, the bonding film 53A contains silver. More specifically, the bonding film 53A is a bonding film containing silver particles. When the bonding film 53A and the bonding material 54 are fired, for example at 200°C, the silver particles of the bonding film 53A and the silver nanoparticles of the bonding material 54 are diffusely bonded by thermocompression. As a result, the substrate 51 and the reflective film 55 are bonded together.

[0035] The bonding film 53A contains silver (Ag) as well as a migration-inhibiting substance that suppresses the movement of silver. In this embodiment, the bonding film 53A contains copper (Cu) as the migration-inhibiting substance. More specifically, the bonding film 53A has a migration-inhibiting layer 533 inside it, which is provided between the first end face 531 on the substrate 51 side of the bonding film 53A and the second end face 532 on the wavelength conversion layer 56 side of the bonding film 53A and is composed of layers of copper particles.

[0036] As described above, the wavelength conversion layer 56 generates heat when converting the excitation light, blue light BL, into fluorescence YL. Since the blue light BL is incident on the surface of the wavelength conversion layer 56 facing the +Z direction, stress is generated inside the wavelength conversion layer 56 due to the temperature difference between the part where the blue light BL is directly incident and the part where the blue light BL is not directly incident. This stress causes the silver particles contained in the bonding film 53A to migrate. For example, silver particles contained in the bonding film 53A may migrate to the bonding material 54 side, or silver particles that were diffusely bonded to silver nanoparticles may migrate. In such cases, delamination may occur between the reflective film 55 and the bonding film 53A, delamination may occur within the bonding film 53A, or delamination may occur between the bonding film 53A and the bonding material 54. If at least one of these delaminations occurs, not only will the bonding strength between the substrate 51 and the wavelength conversion layer 56 decrease, but the heat generated in the wavelength conversion layer 56 cannot be quickly transferred to the substrate 51 side, making it impossible to effectively cool the wavelength conversion layer 56. Furthermore, if the cooling of the wavelength conversion layer 56 is delayed, the conversion efficiency from blue light BL to fluorescence YL by the wavelength conversion layer 56 decreases.

[0037] In response to this, the inventors of this case have found that the occurrence of the above-mentioned delamination can be suppressed by suppressing the movement of silver particles at the joint. Specifically, the inventors of this case have found that by including copper as a movement-inhibiting substance in the bonding film 53A, the movement of silver particles can be suppressed, and the occurrence of the above-mentioned delamination can be suppressed. Furthermore, the inventors of this case have found that by providing a layer of copper between the first end face 531 on the substrate 51 side of the bonding film 53A and the second end face 532 on the wavelength conversion layer 56 side of the bonding film 53A, the movement of silver particles within the bonding film 53A can be effectively suppressed. Specifically, the inventors of this case have found that by forming a movement-inhibiting layer 533 composed of copper particles within the bonding film 53A, the movement of silver particles within the bonding film 53A can be effectively suppressed. Therefore, in the wavelength conversion device 5A with the above configuration, the movement of silver particles within the junction 52A can be effectively suppressed, and the heat generated in the wavelength conversion layer 56 can be efficiently transferred to the substrate 51. This suppresses the decrease in the conversion efficiency from blue light BL to fluorescence YL by the wavelength conversion layer 56, as well as the occurrence of thermal damage to the wavelength conversion layer 56.

[0038] Furthermore, when the dimension of the bonding film 53A along the Z-axis is 100 nm or more and 400 nm or less, the dimension of the migration suppression layer 533 composed of copper particles along the Z-axis is 1 nm or more and 3 nm or less. This is because if the migration suppression layer 533 is relatively thin, the diffusion suppression effect of the silver particles will be low, and if the migration suppression layer 533 is relatively thick, copper particles will diffuse and precipitate on the surface of the bonding film 53A, hindering the bonding between the silver particles and silver nanoparticles. In other words, by keeping the thickness of the migration suppression layer 533 composed of copper particles within the above range, it is possible to simultaneously suppress the diffusion of silver particles and the decrease in bonding strength. Similarly, the ratio of copper to silver in the bonded film 53A is preferably 1 / 400 or more and 3 / 100 or less in terms of moles. By having the ratio of copper to silver within this range, it is possible to simultaneously suppress the diffusion of silver particles and the decrease in bonding strength. Furthermore, if the movement-inhibiting layer 533 is positioned, for example, midway between the first end face 531 and the second end face 532, the diffusion of silver particles can be suppressed more effectively. However, it is not limited to this, and the movement-inhibiting layer 533 can be positioned, for example, between the first end face 531 and the second end face 532.

[0039] [Effects of the First Embodiment] The projector 1 according to this embodiment, as described above, provides the following effects. The projector 1 comprises a light source device 4, a light modulator 34 that modulates the light emitted from the light source device 4, and a projection optical device 36 that projects the light modulated by the light modulator 34. The light source device 4 includes a light source 41 that emits blue light BL, which is the first light, and a wavelength conversion device 5A into which the blue light BL emitted from the light source 41 is incident.

[0040] The wavelength conversion device 5A includes a substrate 51 having a first surface 51A, a joint 52A, a reflective film 55, and a wavelength conversion layer 56. The wavelength conversion layer 56 is positioned on the incident side of the blue light BL relative to the substrate 51 and converts the incident blue light BL into fluorescent YL. The blue light BL corresponds to the first light in the first wavelength band, and the fluorescent YL corresponds to the second light in the second wavelength band, which is different from the first wavelength band. The reflective film 55 is positioned between the wavelength conversion layer 56 and the first surface 51A of the substrate 51, and reflects light incident from the wavelength conversion layer 56. The joint portion 52A is positioned between the reflective film 55 and the first surface 51A of the substrate 51, and joins the reflective film 55 and the substrate 51. The joint portion 52A contains silver and a migration-inhibiting substance that suppresses the movement of silver.

[0041] With this configuration, the joint 52A contains a migration-inhibiting substance that suppresses the movement of silver, thereby preventing the silver from moving over time and reducing the bonding strength of the joint 52A. Consequently, partial delamination between the wavelength conversion layer 56 and the substrate 51 can be suppressed. This prevents a decrease in the heat transfer efficiency from the wavelength conversion layer 56 to the substrate 51, which in turn prevents a decrease in the utilization efficiency of blue light BL by the wavelength conversion layer 56, and consequently, a decrease in the conversion efficiency from blue light BL to fluorescent YL by the wavelength conversion layer 56. Furthermore, this makes it possible to increase the brightness of the light emitted from the light source device 4, and consequently, to increase the brightness of the image projected from the projector 1.

[0042] In the wavelength conversion device 5A, the junction 52A includes a bonding film 53A containing silver and a migration-inhibiting substance, and a bonding material 54 containing silver nanoparticles, which is positioned on the substrate 51 side relative to the bonding film 53A and is bonded to the bonding film 53A. With this configuration, the bonding strength between the reflective film 55 and the base material 51 by the bonding portion 52A can be increased because the bonding portion 52A has a bonding film 53A and a bonding material 54. Furthermore, the inclusion of a migration-inhibiting substance in the bonding film 53A prevents the silver within the bonding film 53A from migrating to the bonding material 54, thereby suppressing partial delamination between the reflective film 55 and the bonding film 53A. Consequently, a decrease in the heat transfer efficiency from the wavelength conversion layer 56 to the substrate 51 via the reflective film 55 can be suppressed, and a decrease in the utilization efficiency of blue light BL by the wavelength conversion layer 56 can be suppressed.

[0043] In the wavelength conversion device 5A, the substrate 51 comprises a substrate 511 having a first surface 511A, and a metal film 512 containing a noble metal and provided on the first surface 511A. The metal film 512 constitutes the first surface 51A. This configuration makes it possible to increase the bonding strength between the base material 51 and the bonding material 54.

[0044] In the wavelength conversion device 5A, the migration-inhibiting material is copper. With this configuration, the movement of silver within the junction 52A is suppressed by the copper. This allows the wavelength conversion device 5A described above to be effectively utilized.

[0045] In the wavelength conversion device 5A, the ratio of copper to silver in the bonding film 53A is between 1 / 400 and 3 / 100 in terms of moles. Here, if the ratio of copper to silver is relatively low, the effect of suppressing silver migration is low, while if the ratio is high, copper is deposited on the surface of the bonding film 53A, and the bonding strength between the bonding film 53A and the bonding material 54 decreases. In contrast, by keeping the copper-to-silver ratio within the above range, it is possible to suppress both the decrease in bonding strength due to silver migration and the decrease in bonding strength due to copper deposition. Therefore, the effects of the wavelength conversion device 5A described above can be effectively realized.

[0046] In the wavelength conversion device 5A, the migration-inhibiting substance is provided in a layer between the first end face 531 on the substrate 51 side of the bonding film 53A and the second end face 532 on the wavelength conversion layer 56 side of the bonding film 53A. With this configuration, copper can be efficiently introduced into the bonding film 53A, and the layered copper effectively suppresses the movement of silver. Therefore, the effects of the wavelength conversion device 5A described above can be effectively realized.

[0047] [Second Embodiment] Next, a second embodiment of this disclosure will be described. The projector according to this embodiment has the same configuration as the projector 1 according to the first embodiment, but the composition of the bonding film in the wavelength conversion device is different. Specifically, the wavelength conversion device according to this embodiment has a different migration-inhibiting substance contained in the bonding film compared to the wavelength conversion device 5A according to the first embodiment. In the following description, parts that are the same or substantially the same as parts already described are denoted by the same reference numerals and their description is omitted.

[0048] [Outline configuration of projector and light source device] Figure 4 shows a cross-section of the wavelength converter 5B of the light source device of the projector according to this embodiment, along the XZ plane. The projector according to this embodiment has the same configuration and functions as the projector 1 according to the first embodiment, except that it is equipped with a wavelength converter 5B shown in Figure 4 instead of the wavelength converter 5A according to the first embodiment. That is, the light source device according to this embodiment has the same configuration and functions as the light source device 4 according to the first embodiment, except that it is equipped with a wavelength converter 5B instead of the wavelength converter 5A.

[0049] [Configuration of the wavelength conversion device] The wavelength conversion device 5B has the same configuration and function as the wavelength conversion device 5A according to the first embodiment, except that it includes a joint 52B instead of the joint 52A according to the first embodiment. That is, the wavelength conversion device 5B includes a base material 51, a joint 52B, a reflective film 55, and a wavelength conversion layer 56, as well as a heat dissipation member 57, which is not shown in Figure 4. The joint 52B has the same configuration and function as the joint 52A according to the first embodiment, except that it has a bonding film 53B instead of the bonding film 53A according to the first embodiment. That is, the joint 52B has a bonding film 53B and a bonding material 54, and bonds the substrate 51, the reflective film 55 and the wavelength conversion layer 56.

[0050] [Composition of the bonding film] The bonding film 53B contains silver (Ag) and also contains a silver alloy as a migration-inhibiting substance. Examples of silver alloys include APC alloy (Ag-Pd-Cu alloy) and APC-TR alloy (manufactured by Furuya Metal Co., Ltd.). Here, the inventors have found that by including the silver alloy exemplified above as a migration-inhibiting substance in the bonding film, the migration of silver particles due to the stress is suppressed, similar to the copper particles in the bonding film 53A according to the first embodiment. For this reason, a wavelength conversion device 5B having a bonding film 53B containing silver and a silver alloy can achieve the same effect as the wavelength conversion device 5A according to the first embodiment, instead of bonding film 53A.

[0051] [Effects of the second embodiment] The projector according to this embodiment, as described above, has the same effects as the projector 1 according to the first embodiment, and also has the following effects. In the wavelength conversion device 5B, the migration suppression material is a silver alloy. With this configuration, the movement of silver in the joint 52B can be suppressed by the silver alloy. Therefore, partial delamination between the wavelength conversion layer 56 and the substrate 51 can be suppressed. As a result, a decrease in the heat transfer efficiency from the wavelength conversion layer 56 to the substrate 51 can be suppressed, and a decrease in the utilization efficiency of blue light BL by the wavelength conversion layer 56, and consequently a decrease in the conversion efficiency from blue light BL to fluorescence YL by the wavelength conversion layer 56, can be suppressed.

[0052] [Third Embodiment] Next, a third embodiment of this disclosure will be described. The projector according to this embodiment has the same configuration as the projector 1 according to the first embodiment, but the composition of the bonding film in the wavelength conversion device is different. In the following description, parts that are the same or substantially the same as parts already described are denoted by the same reference numerals and their description is omitted.

[0053] [Outline configuration of projector and light source device] Figure 5 shows a cross-section of the wavelength conversion device 5C of the projector light source device according to this embodiment, along the XZ plane. The projector according to this embodiment has the same configuration and functions as the projector 1 according to the first embodiment, except that it is equipped with a wavelength converter 5C shown in Figure 5 instead of the wavelength converter 5A according to the first embodiment. That is, the light source device according to this embodiment has the same configuration and functions as the light source device 4 according to the first embodiment, except that it is equipped with a wavelength converter 5C instead of the wavelength converter 5A.

[0054] [Configuration of the wavelength conversion device] The wavelength conversion device 5C has the same configuration and function as the wavelength conversion device 5A according to the first embodiment, except that it includes a joint 52C instead of the joint 52A according to the first embodiment. That is, the wavelength conversion device 5C includes a base material 51, a joint 52C, a reflective film 55, and a wavelength conversion layer 56, as well as a heat dissipation member 57, which is not shown in Figure 5. The joint 52C has the same configuration and function as the joint 52A according to the first embodiment, except that it has a bonding film 53C instead of the bonding film 53A according to the first embodiment. That is, the joint 52C has a bonding film 53C and a bonding material 54, and bonds the substrate 51, the reflective film 55 and the wavelength conversion layer 56.

[0055] [Composition of the bonding film] The bonding film 53C contains silver (Ag) and also contains silver oxide (Ag2O) as a migration inhibitor. More specifically, the bonding film 53C contains silver particles and silver oxide particles. Here, silver oxide is a substance that does not easily diffuse within the bonding film 53C. For this reason, the inventors have found that by using a bonding film 53C containing silver oxide as a migration-inhibiting substance, the migration of silver particles due to the above stress can be suppressed, similar to the copper particles in the bonding film 53A according to the first embodiment. For this reason, a wavelength conversion device 5C having a bonding film 53C instead of bonding film 53A can achieve the same effect as the wavelength conversion device 5A according to the first embodiment. Furthermore, one method for forming the bonding film 53C on the bonding material 54 as a bonding film containing silver and silver oxide is to perform O2 assistance when forming the silver film on the bonding material 54. This makes it possible to form the bonding film 53C containing silver and silver oxide on the bonding material 54.

[0056] [Effects of the third embodiment] The projector according to this embodiment described above provides the same effects as the projector 1 according to the first embodiment, as well as the following effects. In the wavelength conversion device 5C, the migration-inhibiting substance is silver oxide (Ag2O). With this configuration, the movement of silver at the junction 52C can be suppressed by silver oxide (Ag2O). Therefore, the same effect as the wavelength conversion devices 5A and 5B can be achieved.

[0057] [Fourth Embodiment] Next, a fourth embodiment of this disclosure will be described. The projector according to this embodiment has the same configuration as the projector 1 according to the first embodiment, but the composition of the bonding film in the wavelength conversion device is different. In the following description, parts that are the same or substantially the same as parts already described are denoted by the same reference numerals and their description is omitted.

[0058] [Outline configuration of projector and light source device] Figure 6 shows a cross-section of the wavelength converter 5D of the light source device of the projector according to this embodiment, along the XZ plane. The projector according to this embodiment has the same configuration and functions as the projector 1 according to the first embodiment, except that it is equipped with a wavelength converter 5D shown in Figure 6 instead of the wavelength converter 5A according to the first embodiment. That is, the light source device according to this embodiment has the same configuration and functions as the light source device 4 according to the first embodiment, except that it is equipped with a wavelength converter 5D instead of the wavelength converter 5A.

[0059] [Configuration of the wavelength conversion device] The wavelength conversion device 5D has the same configuration and function as the wavelength conversion device 5A according to the first embodiment, except that it includes a joint 52D instead of the joint 52A according to the first embodiment. That is, the wavelength conversion device 5D includes a base material 51, a joint 52D, a reflective film 55, and a wavelength conversion layer 56, as well as a heat dissipation member 57, which is not shown in Figure 5. The joint 52D has the same configuration and function as the joint 52A according to the first embodiment, except that it has a bonding film 53D instead of the bonding film 53A according to the first embodiment. That is, the joint 52D has a bonding film 53D and a bonding material 54, and bonds the substrate 51, the reflective film 55 and the wavelength conversion layer 56.

[0060] [Composition of the bonding film] The bonding film 53D contains silver (Ag) and hydrogen as a migration inhibitor. More specifically, the bonding film 53D contains silver particles and hydrogen. Here, the inventors have found that by including hydrogen as a migration-inhibiting substance in the bonding film, the migration of silver particles due to the above stress is suppressed, similar to the copper particles in the bonding film 53A according to the first embodiment. For this reason, a wavelength conversion device 5D having a bonding film 53D containing silver and hydrogen can achieve the same effect as the wavelength conversion device 5A according to the first embodiment, instead of bonding film 53A. Furthermore, one method for constructing the bonding film 53D containing silver and hydrogen is to incorporate hydrogen into the bonding film by performing a high-temperature annealing treatment on the silver-containing bonding film in a hydrogen atmosphere. Consequently, the bonding material 54 will also contain hydrogen.

[0061] [Effects of the fourth embodiment] The projector according to this embodiment described above provides the same effects as the projector 1 according to the first embodiment, as well as the following effects. In the wavelength conversion device 5D, the substance that inhibits migration is hydrogen. With this configuration, the hydrogen contained in the junction can suppress the movement of silver in the junction 52D. Therefore, it is possible to achieve the same effect as the wavelength conversion devices 5A, 5B, and 5C.

[0062] [Variations of the Embodiment] This disclosure is not limited to the embodiments described above, and any modifications and improvements that can achieve the purposes of this disclosure are included. In the embodiments described above, copper, silver alloy, silver oxide (Ag2O), and hydrogen were mentioned as migration-inhibiting substances. However, the substance is not limited to these, and other substances may be used as long as they can suppress the movement of silver within the joints 52A, 52B, 52C, and 52D.

[0063] In each of the above embodiments, the joints 52A, 52B, 52C, and 52D are said to have a bonding film 53A, 53B, 53C, and 53D containing silver and a migration-inhibiting substance, and a bonding material 54 containing silver nanoparticles. However, the configuration of the joints is not limited to this, and is not limited to the above. For example, the joints may include other layers.

[0064] In the first embodiment described above, the ratio of copper to silver in the bonded film 53A was set to 1 / 400 or more and 3 / 100 or less in terms of moles. However, this ratio is not limited to this, and can be changed as appropriate; it does not necessarily have to be within the range of 1 / 400 or more and 3 / 100 or less.

[0065] In the first embodiment described above, the copper as a migration-inhibiting material was assumed to be provided in a layer within the bonding film 53A. That is, a migration-inhibiting layer 533 composed of copper was assumed to be formed within the bonding film 53A. However, the invention is not limited to this, and the copper as a migration-inhibiting material only needs to be contained within the bonding film 53A.

[0066] In each of the embodiments described above, the optical modulation device 34 of the projector is assumed to include three optical modulation elements 343R, 343G, and 343B. However, the present disclosure is not limited to this and can also be applied to projectors with two or fewer, or four or more, optical modulation elements.

[0067] In the embodiments described above, a transmissive liquid crystal panel with different light incident and light exit surfaces was exemplified as the optical modulation element 343. However, a reflective liquid crystal panel with the same light incident and light exit surfaces may also be used. Furthermore, any optical modulation device capable of modulating the incident light beam to form an image corresponding to image information may be used, such as a device using a micromirror, for example, a DMD (Digital Micromirror Device), or other optical modulation devices other than liquid crystals.

[0068] In the embodiments described above, examples were given in which the light source device of this disclosure is applied to a projector. However, the light source device of this disclosure is not limited to this and may be used in electronic devices other than projectors, such as lighting fixtures and headlights of automobiles, etc. Furthermore, the configurations of the projector and light source device are not limited to those exemplified in the above embodiments and can be modified as appropriate. For example, the light source device only needs to include a light source and a wavelength converter, and other configurations can be modified as appropriate.

[0069] [Summary of this disclosure] A summary of this disclosure is provided below. [Note 1] A substrate having a first surface, A wavelength conversion layer is positioned on the incident side of the substrate to the first light in the first wavelength band, and converts the incident first light into second light in a second wavelength band different from the first wavelength band. A reflective film is disposed between the wavelength conversion layer and the first surface and reflects light incident from the wavelength conversion layer, A joint portion is provided between the reflective film and the first surface, and joins the reflective film and the substrate. Equipped with, The aforementioned joint contains silver and a migration-inhibiting substance that inhibits the movement of silver. A wavelength conversion device characterized by the following features.

[0070] With this configuration, the inclusion of a migration-inhibiting substance in the joint suppresses the movement of silver, thereby preventing the decrease in bonding strength due to silver migration over time. Consequently, partial delamination between the wavelength conversion layer and the substrate can be suppressed. This prevents a decrease in the heat transfer efficiency from the wavelength conversion layer to the substrate, which in turn prevents a decrease in the utilization efficiency of the first light by the wavelength conversion layer, and consequently, a decrease in the conversion efficiency from the first light to the second light by the wavelength conversion layer.

[0071] [Note 2] In the wavelength conversion device described in Appendix 1, The aforementioned joint is A bonding film containing silver and the migration-inhibiting substance, A bonding material containing silver nanoparticles, which is disposed on the substrate side relative to the bonding film and is bonded to the bonding film, A wavelength conversion device characterized by the following features. With this configuration, the bonding strength between the reflective film and the substrate can be increased because the joint has a bonding film and a bonding material. Furthermore, the inclusion of a migration-inhibiting substance in the bonding film prevents the silver within the bonding film from migrating to the bonding material side, thus suppressing partial delamination between the reflective film and the bonding film. Consequently, a decrease in the heat transfer efficiency from the wavelength conversion layer to the substrate via the reflective film can be suppressed, and a decrease in the utilization efficiency of the first light by the wavelength conversion layer can be suppressed.

[0072] [Note 3] In the wavelength conversion device described in Appendix 2, The aforementioned substrate is A substrate having a first surface, It has a metal film containing a precious metal and provided on the first surface, The metal film constitutes the first surface, A wavelength conversion device characterized by the following features. This configuration allows for increased bonding strength between the substrate and the bonding material.

[0073] [Note 4] In the wavelength conversion device described in Appendix 2 or Appendix 3, The aforementioned migration-inhibiting substance is copper. A wavelength conversion device characterized by the following features. With this configuration, the movement of silver is inhibited by the copper. This allows the above effect to be effectively achieved.

[0074] [Note 5] In the wavelength conversion device described in Appendix 4, The ratio of copper to silver in the aforementioned bonded film is between 1 / 400 and 3 / 100 in terms of moles. A wavelength conversion device characterized by the following features. In this case, if the ratio of copper to silver is low, the effect of suppressing silver migration is low, while if the ratio is high, copper is deposited on the surface of the bonded film, reducing the bonding strength. In contrast, by keeping the copper-to-silver ratio within the above range, it is possible to suppress both the decrease in bonding strength due to silver migration and the decrease in bonding strength due to copper deposition. Therefore, the above effects can be effectively achieved.

[0075] [Note 6] In the wavelength conversion device described in Appendix 4 or Appendix 5, The migration-inhibiting material is provided in a layered manner between the first end face on the substrate side of the bonding film and the second end face on the wavelength conversion layer side of the bonding film. A wavelength conversion device characterized by the following features. This configuration allows for efficient introduction of copper into the bonding film, and the layered copper effectively suppresses the movement of silver. Therefore, the above effects can be effectively achieved.

[0076] [Note 7] In the wavelength conversion device described in any one of the appendices 1 to 3, The aforementioned migration-inhibiting material is a silver alloy. A wavelength conversion device characterized by the following features. With this configuration, the movement of silver can be suppressed by the silver alloy. Therefore, the above effect can be effectively achieved.

[0077] [Note 8] In the wavelength conversion device described in any one of the appendices 1 to 3, The aforementioned migration-inhibiting substance is silver oxide. A wavelength conversion device characterized by the following features. With this configuration, the movement of silver can be suppressed by silver oxide (Ag2O). Therefore, the above effect can be effectively achieved.

[0078] [Note 9] In the wavelength conversion device described in any one of the appendices 1 to 3, The aforementioned transport-inhibiting substance is hydrogen. A wavelength conversion device characterized by the following features. With this configuration, the movement of silver can be suppressed by the hydrogen contained in the junction. Therefore, the above effect can be effectively achieved.

[0079] [Note 10] The light source that emits the first light, The wavelength conversion device described in any one of the appendices 1 to 9, into which the first light emitted from the light source is incident, Equipped with, A light source device characterized by the following features. Such a light source device can achieve the same effect as the wavelength conversion device described above. Therefore, the wavelength conversion efficiency from the first light to the second light by the wavelength conversion device is improved, and the brightness of the light emitted from the light source device can be increased.

[0080] [Note 11] The light source device described in Appendix 10, A light modulator that modulates the light emitted from the light source device, A projection optical device that projects light modulated by the aforementioned optical modulation device, Equipped with, A projector characterized by the following features. Such projectors can achieve the same effect as the light source devices described above. This allows for an increase in the brightness of the image projected from the projector. [Explanation of symbols]

[0081] 1...Projector, 34...Optical modulation device, 36...Projection optical device, 4...Light source device, 41...Light source, 5A, 5B, 5C, 5D...Wavelength conversion device, 51...Substrate, 51A...First surface, 511...Substrate, 511A...First surface, 512...Metal film, 52A, 52B, 52C, 52D...Joint portion, 53A, 53B, 53C, 53D...Bonding film, 531...First end face, 532...Second end face, 533...Movement suppression layer, 54...Bonding material, 55...Reflective film, 56...Wavelength conversion layer, 57...Heat dissipation member.

Claims

1. A substrate having a first surface, A wavelength conversion layer is positioned on the incident side of the substrate to the first light in the first wavelength band, and converts the incident first light into second light in a second wavelength band different from the first wavelength band. A reflective film is disposed between the wavelength conversion layer and the first surface and reflects light incident from the wavelength conversion layer, A joint portion is provided between the reflective film and the first surface, and joins the reflective film and the substrate. Equipped with, The aforementioned joint contains silver and a migration-inhibiting substance that inhibits the movement of silver. A wavelength conversion device characterized by the following features.

2. In the wavelength conversion apparatus according to claim 1, The aforementioned joint is A bonding film containing silver and the migration-inhibiting substance, A bonding material containing silver nanoparticles, which is disposed on the substrate side relative to the bonding film and is bonded to the bonding film, A wavelength conversion device characterized by the following features.

3. In the wavelength conversion apparatus according to claim 2, The aforementioned substrate is A substrate having a first surface, It has a metal film containing a precious metal and provided on the first surface, The metal film constitutes the first surface, A wavelength conversion device characterized by the following features.

4. In the wavelength conversion apparatus according to claim 2, The aforementioned migration-inhibiting substance is copper. A wavelength conversion device characterized by the following features.

5. In the wavelength conversion apparatus according to claim 4, The ratio of copper to silver in the aforementioned bonding film is between 1 / 400 and 3 / 100 in terms of moles. A wavelength conversion device characterized by the following features.

6. In the wavelength conversion device according to claim 4 or claim 5, The migration-inhibiting material is provided in a layered manner between the first end face on the substrate side of the bonding film and the second end face on the wavelength conversion layer side of the bonding film. A wavelength conversion device characterized by the following features.

7. In the wavelength conversion apparatus according to any one of claims 1 to 3, The aforementioned migration-inhibiting material is a silver alloy. A wavelength conversion device characterized by the following features.

8. In the wavelength conversion apparatus according to any one of claims 1 to 3, The aforementioned migration-inhibiting substance is silver oxide. A wavelength conversion device characterized by the following features.

9. In the wavelength conversion apparatus according to any one of claims 1 to 3, The aforementioned transport-inhibiting substance is hydrogen. A wavelength conversion device characterized by the following features.

10. The first light source that emits light, A wavelength conversion device according to any one of claims 1 to 3, into which the first light emitted from the light source is incident, Equipped with, A light source device characterized by the following features.

11. The light source device according to claim 10, A light modulator that modulates the light emitted from the light source device, A projection optical device that projects light modulated by the aforementioned optical modulation device, Equipped with, A projector characterized by the following features.

Images