Wavelength conversion device and projector

Abstract

To provide a wavelength conversion device which is high in the use efficiency of light, a projector and a fluorescent body ceramic member.SOLUTION: A wavelength conversion device 1 used for a projector 100, receiving excitation light L1, and irradiating reflection light L2 including fluorescent light comprises: a baseboard 10 having a light reflection face 13; and a fluorescent body ceramic layer 20 formed above the light reflection face 13, and including a first crystal phase having a garnet structure. A visible light reflection rate of the light reflection face 13 is equal to or higher than 95% and equal to or lower than 100%, the density of the fluorescent body ceramic layer 20 is equal to or higher than 97% and equal to or lower than 100% at theoretical density, and a film thickness of the fluorescent body ceramic layer 20 is equal to or thicker than 50 μm and thinner than 120 μm.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a wavelength conversion device, a projector using the same, and a phosphor ceramic member.

Background Art

[0002] Conventionally, wavelength conversion devices used in projectors are known.

[0003] For example, Patent Document 1 discloses a wavelength conversion device including a substrate having a circular shape in plan view and a phosphor layer (phosphor ceramic member) provided along the circumferential direction of the substrate, and being rotatable by a motor connected to the center of the substrate. In Patent Document 1, this wavelength conversion device functions as a reflective phosphor wheel in a projector, and the fluorescence emitted from the phosphor layer of this wavelength conversion device is used as the light (projection light) emitted by the projector.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the above conventional wavelength conversion device, projector, and phosphor ceramic member have a problem of low light utilization efficiency. Therefore, the present invention provides a wavelength conversion device, a projector, and a phosphor ceramic member with high light utilization efficiency.

Means for Solving the Problems

[0006] A wavelength conversion device according to one aspect of the present invention is a wavelength conversion device used in a projector, which receives excitation light and emits reflected light including fluorescence, and includes a substrate having a light reflection surface, and a phosphor ceramic layer located above the light reflection surface and including a first crystal phase having a garnet structure. The visible light reflectivity of the light reflection surface is 95% or more and 100% or less, the density of the phosphor ceramic layer is 97% or more and 100% or less of the theoretical density, and the film thickness of the phosphor ceramic layer is 50 μm or more and less than 120 μm.

[0007] Moreover, a projector according to one aspect of the present invention includes an excitation light source that emits excitation light, and the above-described wavelength conversion device that receives the excitation light and emits reflected light including fluorescence.

[0008] Also, a phosphor ceramic member according to one aspect of the present invention is a phosphor ceramic member used in a projector, and includes a first crystal phase having a garnet structure and a second crystal phase having a structure other than the garnet structure. The density of the phosphor ceramic member is 97% or more and 100% or less of the theoretical density, and the film thickness of the phosphor ceramic member is 50 μm or more and less than 300 μm.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a wavelength conversion device, a projector, and a phosphor ceramic member with high light utilization efficiency.

Brief Description of the Drawings

[0010]

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DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a wavelength conversion device and the like according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0012] Note that each of the embodiments described below shows comprehensive or specific examples. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, manufacturing processes, order of manufacturing processes, etc. shown in the following embodiments are examples, and are not intended to limit the present invention. In addition, among the components in the following embodiments, components not described in the independent claims are described as optional components.

[0013] In addition, each figure is a schematic diagram and is not necessarily drawn precisely. Therefore, for example, scales etc. in each figure do not necessarily match. Also, in each figure, substantially the same configurations are denoted by the same reference numerals, and overlapping explanations are omitted or simplified.

[0014] In this specification, terms indicating the relationship between elements such as parallel or orthogonal, terms indicating the shape of elements such as circular or elliptical, and numerical ranges are not expressions representing only a strict meaning, but are expressions meaning substantially equivalent ranges, for example, including a difference of about several percent.

[0015] Also, in this specification, "plan view" means the case of viewing the wavelength conversion device along the direction perpendicular to the light reflection surface of the substrate.

[0016] Also, in this specification, the terms "upper" and "lower" in the configuration of the wavelength conversion device do not refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition, but are terms defined by the relative positional relationship based on the stacking order in the stacked structure. Also, the terms "above" and "below" are applicable not only when two components are spaced apart from each other and there is another component between the two components, but also when two components are arranged in close contact with each other and the two components are in contact.

[0017] Also, in this specification and the drawings, the x-axis, y-axis, and z-axis indicate the three axes of a three-dimensional orthogonal coordinate system. In each embodiment, two axes parallel to the light reflection surface of the substrate are taken as the x-axis and y-axis, Light reflecting surface and the direction orthogonal to them is taken as the z-axis direction. Also, in each embodiment described below, there may be cases where the positive direction of the z-axis is described as upward and the negative direction of the z-axis is described as downward.

[0018] (Embodiment) [Configuration of Wavelength Conversion Device] First, the configuration of the wavelength conversion device 1 according to the present embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of the wavelength conversion device 1 according to the present embodiment. FIG. 2 is a cross-sectional view showing a cross-section of the wavelength conversion device 1 taken along line II-II of FIG. 1.

[0019] As shown in FIGS. 1 and 2, the wavelength conversion device 1 is a device including a substrate 10 having a light reflection surface 13, a phosphor ceramics layer 20, and an antireflection layer 30.

[0020] In the present embodiment, the wavelength conversion device 1 is a phosphor wheel that is used in a projector, receives excitation light L1, and emits reflected light including fluorescence. The wavelength conversion device 1 has a disk shape, and a motor 4 for rotational drive is provided at the center of the wavelength conversion device 1 in a plan view. Therefore, the wavelength conversion device 1 is rotationally driven in the direction of the arrow shown in FIG. 1 about the motor 4 by the motor 4.

[0021] In addition, in FIG. 1, the configuration of the phosphor wheel provided with the motor 4 is shown, but the wavelength conversion device 1 may not include the motor 4. That is, the wavelength conversion device 1 may be a fixed device that is not rotationally driven. With such a configuration, the wavelength conversion device 1 becomes small, so a compact projector can be provided.

[0022] The phosphor ceramics layer 20 is a layer located above the light reflection surface 13 of the substrate 10. In the present embodiment, since the wavelength conversion device 1 is a phosphor wheel, the phosphor ceramics layer 20 is a phosphor ring. The phosphor ceramics layer 20 is provided in a ring shape on a circumference where the distance from the rotation center of the wavelength conversion device 1 (that is, the location where the motor 4 is provided) is equal. That is, the phosphor ceramics layer 20 is provided in a band shape along the circumferential direction in a plan view.

[0023] The phosphor ceramic layer 20 contains a first crystal phase having a garnet structure. More specifically, in the present embodiment, the phosphor ceramic layer 20 is composed only of the first crystal phase having a garnet structure. That is, the phosphor ceramic layer 20 according to the present embodiment does not contain a crystal phase having a structure different from the garnet structure. The garnet structure is a crystal structure represented by the general formula A3B2C3O 12 is a crystal structure represented by the general formula. As the element A, rare earth elements such as Ca, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Lu are applicable, as the element B, elements such as Mg, Al, Si, Ga, and Sc are applicable, and as the element C, elements such as Al, Si, and Ga are applicable. Such garnet structures include YAG (Yttrium Aluminum Garnet), LuAG (Lutetium Aluminum Garnet), Lu2CaMg2Si3O 12 (Lutetium Calcium Magnesium Silicon Garnet), and TAG (Terbium Aluminum Garnet). In the present embodiment, the phosphor ceramic layer 20 is composed of a first crystal phase represented by (Y 1-x Ce x )3Al2Al3O 12 (that is, (Y 1-x Ce x )3Al5O 12 )(0.001 ≦ x < 0.1), that is, it is composed of YAG.

[0024] Note that the first crystal phase constituting the phosphor ceramic layer 20 may be a solid solution of a plurality of garnet crystal phases having different chemical compositions. Such solid solutions include (Y 1-x Ce x )3Al2Al3O 12 (0.001 ≦ x < 0.1) and (Lu 1-d Ce d )3Al2Al3O12 (0.001 ≦ d < 0.1) represented solid solution with garnet crystal phase ((1 - a)(Y 1-x Ce x )3Al5O 12 ·a(Lu 1-d Ce d )3Al2Al3O 12 (0 < a < 1)) can be mentioned. Further, as such a solid solution, (Y 1-x Ce x )3Al2Al3O 12 (0.001 ≦ x < 0.1) represented solid solution with garnet crystal phase and (Lu 1-z Ce z )2CaMg2Si3O 12 (0.0015 ≦ z < 0.15) represented solid solution with garnet crystal phase ((1 - b)(Y 1-x Ce x )3Al2Al3O 12 ·b(Lu 1-z Ce z )2CaMg2Si3O 12 (0 < b < 1)) etc. can be mentioned. Since the phosphor ceramic layer 20 is composed of solid solutions of a plurality of garnet crystal phases with different chemical compositions, the fluorescence spectrum of the fluorescence emitted by the phosphor ceramic layer 20 becomes wider, and the green light component and the red light component increase. Therefore, a projector that emits projection light with a wide color gamut can be provided.

[0025] Also, the first crystal phase constituting the phosphor ceramic layer 20 may contain a crystal phase with a chemical composition shifted from the crystal phase represented by the above general formula A3B2C3O 12 . As such a crystal phase, (Y 1-x Ce x )3Al2Al3O 12 (0.001 ≦ x < 0.1) represented crystal phase with Al-rich (Y 1-x Ce x )3Al 2+δ Al3O 12 (δ is a positive number) can be mentioned. Also, as such a crystal phase, (Y 1-x Ce x )3Al2Al3O 12(0.001 ≦ x < 0.1), for the crystal phase represented by Y is rich in (Y 1-x Ce x ) 3+ζ Al2Al3O 12 (ζ is a positive number), etc. These crystal phases have a chemical composition deviation from the crystal phase represented by the general formula A3B2C3O 12 but maintain the garnet structure. Since the phosphor ceramic layer 20 is composed of crystal phases with a chemical composition deviation, regions with different refractive indices are generated in the phosphor ceramic layer 20, so that the excitation light L1 and fluorescence are more scattered, and the light-emitting area of the phosphor ceramic layer 20 becomes smaller. Therefore, a wavelength conversion device 1 and a projector with a smaller étendue and higher light utilization efficiency can be provided.

[0026] Furthermore, the phosphor ceramic layer 20 may include a first crystal phase and a heterogeneous phase having a structure other than the garnet structure. Since the phosphor ceramic layer 20 is composed of such a first crystal phase and heterogeneous phase, regions with different refractive indices are generated in the phosphor ceramic layer 20, so that the excitation light L1 and fluorescence are more scattered, and the light-emitting area of the phosphor ceramic layer 20 becomes smaller. Therefore, a wavelength conversion device 1 and a projector with a smaller étendue and higher light utilization efficiency can be provided.

[0027] The phosphor ceramic layer 20 composed of YAG receives the light incident from above the wavelength conversion device 1 as the excitation light L1 and emits fluorescence. More specifically, when the light emitted from the excitation light source described later is irradiated on the phosphor ceramic layer 20 as the excitation light L1, fluorescence is emitted from the phosphor ceramic layer 20 as wavelength-converted light. That is, the wavelength-converted light emitted from the phosphor ceramic layer 20 is light with a wavelength longer than the wavelength of the excitation light L1.

[0028] In this embodiment, the wavelength-converted light emitted from the phosphor ceramic layer 20 includes fluorescence which is yellow light. The phosphor ceramic layer 20 absorbs light having a wavelength of 380 nm or more and 490 nm or less, for example, and emits fluorescence which is yellow light having a fluorescence peak wavelength in the region of 490 nm or more and 580 nm or less. By configuring the phosphor ceramic layer 20 with YAG, a phosphor ceramic layer 20 that easily emits fluorescence having a fluorescence peak wavelength in the region of 490 nm or more and 580 nm or less is realized.

[0029] The x coordinate of the chromaticity diagram of the wavelength-converted light emitted from the phosphor ceramic layer 20 may be 0.415 or less, more preferably 0.410 or less, and even more preferably 0.408 or less. When the x coordinate of the chromaticity diagram of the wavelength-converted light emitted from the phosphor ceramic layer 20 is the above numerical value, the temperature quenching of the phosphor ceramic layer 20 becomes small, so that a phosphor ceramic layer 20 with high luminous efficiency can be realized.

[0030] The density of the phosphor ceramic layer 20 may be 95% or more and 100% or less of the theoretical density, and more preferably 97% or more and 100% or less of the theoretical density. Here, the theoretical density is the density when the atoms in the layer are ideally arranged. In other words, the theoretical density is the density assuming that there are no voids in the phosphor ceramic layer 20, and is a value calculated using the crystal structure. For example, when the density of the phosphor ceramic layer 20 is 99%, the remaining 1% corresponds to voids. That is, the higher the density of the phosphor ceramic layer 20, the fewer the voids. When the density of the phosphor ceramic layer 20 is in the above range, the total amount of fluorescence emitted by the phosphor ceramic layer 20 increases, so that a wavelength conversion device 1 and a projector that emit more light can be provided.

[0031] Also, the density of the phosphor ceramic layer 20 may be 4.32 g / cm 3 or more and 4.55 g / cm 3 or less, and 4.41 g / cm 3 or more and 4.55 g / cm 3The following would be better. As shown in this embodiment, when the phosphor ceramic layer 20 is made of YAG, if the density of the phosphor ceramic layer 20 is within the above range, the density of the phosphor ceramic layer 20 will be 95% or more and 100% or less, and 97% or more and 100% or less of the theoretical density, respectively. When the density of the phosphor ceramic layer 20 is within the above range, the excitation light L1 absorbed by the phosphor ceramic layer 20 can be efficiently converted into fluorescence. That is, a phosphor ceramic layer 20 with high luminous efficiency is realized.

[0032] The film thickness (length in the z-axis direction) of the phosphor ceramic layer 20 is preferably 50 μm or more and less than 150 μm, and more preferably 50 μm or more and less than 120 μm. Also, the film thickness of the phosphor ceramic layer is more preferably 70 μm or more and less than 120 μm, and even more preferably 80 μm or more and less than 110 μm.

[0033] Furthermore, an antireflection layer 30 is located above the phosphor ceramic layer 20.

[0034] The antireflection layer 30 is a layer that prevents, more specifically suppresses, the reflection of the excitation light L1. The antireflection layer 30 reduces the reflectivity of the excitation light L1 in the wavelength conversion device 1 and increases the amount of excitation light L1 reaching the phosphor ceramic layer 20. As a result, the amount of excitation light L1 that the phosphor ceramic layer 20 can absorb also increases, so the amount of fluorescence emitted by the phosphor ceramic layer 20 also increases. That is, by providing the antireflection layer 30, the amount of fluorescence emitted by the phosphor ceramic layer 20 increases.

[0035] The antireflection layer 30 may be composed of, for example, a dielectric film or a fine concavo-convex structure (so-called moth-eye structure) with a period smaller than the wavelength of light in the visible light region. When the antireflection layer 30 is composed of a dielectric film, the antireflection layer 30 preferably contains an inorganic compound. In this case, the antireflection layer 30 contains one or more inorganic compounds selected from SiO2, TiO2, Al2O3, ZnO, Nb2O5, and MgF, etc.

[0036] In addition, in FIGS. 1 and 2, a configuration in which an antireflection layer 30 is provided is shown, but the wavelength conversion device 1 may not include the antireflection layer 30.

[0037] The substrate 10 is a disk-shaped plate material and is a base material that supports the phosphor ceramics layer 20 and the antireflection layer 30. The motor 4 is provided at the center of the substrate 10 in a plan view. As shown in FIG. 2, the substrate 10 has a substrate body 11 and a light reflection layer 12.

[0038] The substrate body 11 is preferably made of a material with high thermal conductivity. For example, the substrate body 11 is preferably made of a material with higher thermal conductivity than the phosphor ceramics layer 20, but is not limited thereto. Examples of the substrate body 11 include a glass substrate, a quartz substrate, a GaN substrate, a sapphire substrate, an Si substrate, and a metal substrate. Further, the substrate body 11 may be made of a resin such as a PEN (polyethylene naphthalate) film or a PET (polyethylene terephthalate) film. Furthermore, when the substrate body 11 is a metal substrate, the substrate body 11 is made of a metal material such as Al, Fe, and Ti.

[0039] In the present embodiment, the substrate body 11 is a metal substrate made of Al. Since Al has high thermal conductivity and is lightweight, the heat dissipation of the substrate body 11 can be enhanced, and the weight of the substrate body 11 can be reduced. The thickness of the substrate body 11 is, for example, 1.5 mm or less.

[0040] In addition, the substrate 10 has a light reflection surface 13. The light reflection surface 13 is one surface of the substrate 10 on the side where the phosphor ceramics layer 20 is located. In the present embodiment, the light reflection surface 13 is constituted by one surface included in the light reflection layer 12.

[0041] The light reflection surface 13 is a surface that reflects the fluorescence emitted by the phosphor ceramic layer 20. Also, the light reflection surface 13 reflects the excitation light L1 that was not converted into fluorescence in the phosphor ceramic layer 20. The light reflection surface 13 reflects the fluorescence and the excitation light L1 that was not converted into fluorescence upward. In the present embodiment, since the fluorescence and the excitation light L1 are light in the visible light region, the higher the visible light reflectance of the light reflection surface 13, the less the light loss. Specifically, the visible light reflectance of the light reflection surface 13 may be 90% or more and 100% or less, and more preferably 95% or more and 100% or less. When the visible light reflectance of the light reflection surface 13 is within the above range, the fluorescence and the excitation light L1 are reflected more upward, so the waveguide of the fluorescence and the excitation light L1 in the lateral direction (that is, the direction parallel to the light reflection surface 13) is suppressed, and the light emitting area becomes smaller. For this reason, it is possible to provide a wavelength conversion device 1 and a projector with a smaller étendue and higher light utilization efficiency. Also, the reflectance of the light in the wavelength region of 490 nm or more and 780 nm or less of the light reflection surface 13 may be 90% or more and 100% or less, and more preferably 95% or more and 100% or less. When the reflectance of the light in the wavelength region of 490 nm or more and 780 nm or less of the light reflection surface 13 is within the above range, the fluorescence is reflected more upward, so the waveguide of the fluorescence in the lateral direction is suppressed, and the light emitting area becomes smaller. For this reason, it is possible to provide a wavelength conversion device 1 and a projector with a smaller étendue and higher light utilization efficiency. Note that in the present embodiment, the visible light region is a wavelength region with a wavelength of 380 nm or more and 780 nm or less.

[0042] The light reflection layer 12 may be made of any material as long as it can reflect the fluorescence and the excitation light L1 that was not converted into fluorescence upward. In the present embodiment, the light reflection layer 12 is a composite layer composed of light scattering particles 121 and a binder 122 in which the light scattering particles 121 are dispersed. That is, the light reflection layer 12 has light diffusibility (light scattering property) and reflects the fluorescence and the excitation light L1 that was not converted into fluorescence upward by light diffusion.

[0043] The light reflection layer 12 diffuses light due to the refractive index difference between the light-scattering particles 121 and the binder 122. The light-scattering particles 121 are, for example, fillers or white particles composed of an inorganic compound or a resin material. More specifically, the light-scattering particles 121 may be inorganic compounds such as SiO2, TiO2, Al2O3, ZnO, Nb2O5, ZrO2, and CaCO3, or resin materials such as styrene resins and acrylic resins. Further, the binder 122 is preferably composed of a resin material such as a light-transmissive acrylic resin and a silicone resin.

[0044] By providing the light reflection layer 12, the visible light reflectance of the light reflection surface 13 can be increased. Further, since the light reflection layer 12 is composed of a composite layer containing the light-scattering particles 121, the visible light reflectance of the light reflection surface 13 can be further increased. That is, the loss of light in the wavelength conversion device 1 can be further suppressed.

[0045] Note that the light reflection layer 12 may be a metal layer composed of a metal having light reflectivity. For example, the metal is Ag, Al, or an alloy containing any of these. The light reflection layer 12 is preferably formed by a dry process or a wet process using the metal. Even in such a case, the same operational effects as those when the light reflection layer 12 is composed of a composite layer containing the light-scattering particles 121 are expected.

[0046] Further, a bonding layer may be provided between the light reflection layer 12 and the phosphor ceramics layer 20. With such a configuration, the light reflection layer 12 and the phosphor ceramics layer 20 are more closely adhered, so that the heat generated in the phosphor ceramics layer 20 can be efficiently conducted to the substrate body 11 through the light reflection layer 12. Therefore, a highly efficient wavelength conversion device 1 with less temperature quenching of the phosphor ceramics layer 20 can be provided. The bonding layer is preferably made of a transparent material such as a silicone resin or an epoxy resin. Further, the thickness of the bonding layer may be 1 μm or more and less than 100 μm, and more preferably 1 μm or more and less than 20 μm.

[0047] In FIGS. 1 and 2, a configuration in which the light reflection layer 12 is provided is shown. However, the wavelength conversion device 1 may not include the light reflection layer 12. In this case, the surface of the substrate main body 11 serves as the light reflection surface 13.

[0048] [Configuration of Projector] The wavelength conversion device 1 configured as described above is used in the projector 100 shown in FIGS. 3 and 4. FIG. 3 is a perspective view showing the appearance of the projector 100 according to the present embodiment. FIG. 4 is a schematic diagram showing the optical system of the projector 100 according to the present embodiment. Hereinafter, the configuration of the projector 100 according to the present embodiment will be described with reference to FIGS. 3 and 4.

[0049] As shown in FIGS. 3 and 4, the projector 100 according to the present embodiment includes a light source 3, a dichroic mirror 5, a wavelength conversion device 1, a display element 6, a projection optical member 7, and a reflection mirror 8.

[0050] The light source 3 is, for example, a semiconductor laser light source or an LED (Light Emitting Diode) light source, and is driven by a drive current to emit light of a predetermined color (wavelength).

[0051] In the present embodiment, the light source 3 is a semiconductor laser light source. Note that the semiconductor laser element included in the light source 3 is is, for example, a GaN-based semiconductor laser element (laser chip) made of a nitride semiconductor material. In the present embodiment, the light source 3 that is a semiconductor laser light source is a multi-chip type light emitting device.

[0052] As an example, the light source 3 emits laser light in the range from near ultraviolet to blue having a peak wavelength of 380 nm or more and 490 nm or less. More specifically, the light source 3 emits blue light having a peak wavelength of 445 nm. The light source 3 according to the present embodiment is an example of an excitation light source. The laser light emitted by the light source 3 reaches the dichroic mirror 5.

[0053] The dichroic mirror 5 is arranged at an angle of 45 degrees with respect to the optical axis of the light source 3. The dichroic mirror 5 according to the present embodiment is a dichroic mirror that transmits a part of the blue light and reflects the other part, and transmits the yellowish fluorescence.

[0054] That is, the dichroic mirror 5 has the characteristics of reflecting and transmitting the light in the wavelength region of the laser light emitted from the light source 3. Therefore, a part of the laser light emitted from the light source 3 passes through the dichroic mirror 5 without the traveling direction being changed, and the other part of the laser light is reflected by the dichroic mirror 5, the traveling direction is changed by 90°, and it heads toward the wavelength conversion device 1.

[0055] Here, the other part of the laser light emitted from the light source 3 reaches the wavelength conversion device 1 as the excitation light L1. The wavelength conversion device 1 receives the excitation light L1 and emits the reflected light L2 including fluorescence. More specifically, the reflected light L2 includes the light wavelength-converted and reflected by the phosphor ceramics layer 20 and the light reflection surface 13 provided in the wavelength conversion device 1, respectively. More specifically, the reflected light L2 is light including the yellowish fluorescence generated in the phosphor ceramics layer 20 and the excitation light L1 which is the blue light not converted into fluorescence in the phosphor ceramics layer 20. However, since the proportion of fluorescence in the reflected light L2 is high, the reflected light L2 is yellowish light.

[0056] The laser light that has passed through the dichroic mirror 5 without the traveling direction being changed reaches the reflection mirror 8 as the transmitted light L12, is specularly reflected by the reflection mirror 8, and heads toward the other surface of the dichroic mirror 5. Then, the transmitted light L12 is reflected by the other surface of the dichroic mirror 5, the traveling direction is changed by 90°, and it heads toward the display element 6.

[0057] Also, the reflected light L2 reaches the dichroic mirror 5. At this time, the dichroic mirror 5 is arranged at an angle of 45 degrees with respect to the optical axis of the reflected light L2, and also transmits the yellowish fluorescence. Therefore, the traveling direction of the reflected light L2 that has reached the dichroic mirror 5 does not change.

[0058] As a result, as shown in FIG. 4, the optical axis of the reflected light L2 and the optical axis of the transmitted light L12 coincide and are directed toward the display element 6. At this time, since the reflected light L2 is yellowish light and the transmitted light L12 is blue light, the light obtained by combining these lights is white light. That is, the light traveling from the dichroic mirror 5 toward the display element 6 is white light.

[0059] The white light, which is the mixed light of the reflected light L2 and the transmitted light L12, travels toward the display element 6. Here, if the reflected light L2 is light with a large étendue, the size of the reflected light L2 irradiated toward the display element 6 becomes larger than the size of the display element 6. Therefore, there are more ineffective (i.e., unusable) light components that do not irradiate the display element 6.

[0060] The display element 6 is a substantially planar element that controls the light (white light) passing through the aperture 2a and outputs it as an image. In other words, the display element 6 generates light for an image. Specifically, the display element 6 is a DLP (Digital Light Processing) having a DMD (Digital Micromirror Device). Further, for example, the display element 6 may be a reflective liquid crystal panel or the like. Note that a fly-eye lens, a polarization conversion element, a mirror rod, or the like may be provided between the display element 6 and the dichroic mirror 5.

[0061] The light for the image generated by the display element 6 becomes projection light that is enlarged and projected onto the screen by the projection optical member 7.

[0062] In the projector 100, only the light irradiated on the display element 6 is used as projection light. That is, the smaller the étendue of the reflected light L2, the more light can be used as the projection light of the projector 100.

[0063] [Light Behavior in Wavelength Conversion Device] Here, the light behavior in the wavelength conversion device 1 will be described using this embodiment and a comparative example.

[0064] FIG. 5A is a schematic diagram showing the wavelength conversion device 1 and the aperture member 2 according to the present embodiment. FIG. 5B is a schematic diagram showing the wavelength conversion device 1x and the aperture member 2 according to the comparative example of the present embodiment. Here, for simplicity, the aperture member 2, the wavelength conversion devices 1 and 1x, the excitation light L1, and the reflected light L2 will be used for explanation.

[0065] Here, the aperture member 2 is a member for evaluating the étendue of the reflected light L2. The aperture member 2 is a member that absorbs light, and an opening 2a is provided at the center of the aperture member 2. It can be said that the étendue of the reflected light L2 is small when the ratio of the light component passing through the opening 2a of the aperture member 2 is relatively large.

[0066] The wavelength conversion device 1x according to the comparative example has the same configuration as the wavelength conversion device 1 according to the present embodiment, except that the thickness of the phosphor ceramics layer 20x is thicker (for example, 200 μm) than the phosphor ceramics layer 20 according to the present embodiment.

[0067] The densities of the phosphor ceramics layers 20 and 20x are from 4.41 g / cm 3 to 4.55 g / cm 3 below, and the density is high. That is, in the phosphor ceramics layers 20 and 20x, there are few voids and light scattering hardly occurs, so light easily travels in the plane direction of the layer (that is, the x-axis direction or the y-axis direction), and so-called light guiding easily occurs.

[0068] First, the wavelength conversion device 1 according to the present embodiment will be described with reference to FIG. 5A.

[0069] When the thickness is sufficiently thin (50 μm or more and 120 μm or less) like the phosphor ceramic layer 20 according to the present embodiment, the distance D in the planar direction (here, the x-axis direction) of the layer from when the excitation light L1 is incident until the reflected light L2 is emitted can be made shorter. In other words, in the present embodiment, the light-emitting area (emission spot diameter) of the fluorescence of the phosphor ceramic layer 20 is sufficiently small. Therefore, as shown in FIG. 5A, the reflected light L2 reflected by the light reflection surface 13 and emitted from the phosphor ceramic layer 20 easily passes through the opening 2a of the aperture member 2. The light that has passed through the opening 2a can be used as light that is enlarged and projected onto the screen via the display element 6 and the projection optical member 7 as described above.

[0070] That is, in the present embodiment, since the thickness of the phosphor ceramic layer 20 included in the wavelength conversion device 1 is sufficiently thin, the light-emitting area of the fluorescence can be made sufficiently small. Therefore, since a lot of light passes through the opening 2a of the aperture member 2, a lot of light can be used as the projection light of the projector 100. That is, with the above configuration, a wavelength conversion device 1 with high light utilization efficiency is realized. Furthermore, by providing such a wavelength conversion device 1, a projector 100 with high light utilization efficiency is realized.

[0071] Subsequently, the wavelength conversion device 1x according to the comparative example will be described with reference to FIG. 5B.

[0072] When the thickness is sufficiently thick (200 μm) like the phosphor ceramic layer 20x according to the comparative example, the distance Dx in the planar direction of the layer from when the excitation light L1 is incident until the reflected light L2x is emitted becomes longer. In other words, in the comparative example, the light-emitting area (emission spot diameter) of the fluorescence of the phosphor ceramic layer 20x becomes large. Therefore, as shown in FIG. 5B, the reflected light L2x reflected by the light reflection surface 13 and emitted from the phosphor ceramic layer 20x is easily blocked by the aperture member 2. Therefore, in the wavelength conversion device 1x according to the comparative example, the light utilization efficiency is low.

[0073] Further, as described above, in the present embodiment, the light reflection layer 12 is provided, and further, the light reflection layer 12 is composed of a composite layer containing light-scattering particles 121, so that the visible light reflectance of the light reflection surface 13 can be further increased. As a result, the loss of light in the wavelength conversion device 1 can be further suppressed, and thus the wavelength conversion device 1 with high light utilization efficiency is realized.

[0074] [Example] Here, in the wavelength conversion devices according to Examples 1 to 3 and the comparative example of the present embodiment, the manufacturing method and the light utilization efficiency will be described.

[0075] First, the manufacturing method of the phosphor ceramic layer will be described.

[0076] The phosphor ceramic layers according to Examples 1 to 3 and the comparative example are all composed of a first crystal phase represented by (Y 0.9953 Ce 0.0047 )3Al5O 12 . Further, the phosphor ceramic layers according to Examples 1 to 3 and the comparative example are all composed of Ce 3+ -activated phosphors.

[0077] The following three types were used as raw materials for the phosphor ceramic layers according to Examples 1 to 3 and the comparative example. Specifically, Y2O3 (yttrium oxide, purity 3N, Nippon Yttrium Co., Ltd.), Al2O3 (aluminum oxide, purity 3N, Sumitomo Chemical Co., Ltd.) and CeO2 (cerium oxide, purity 3N, Nippon Yttrium Co., Ltd.) were used.

[0078] First, a compound (Y 0.9953 Ce 0.0047 )3Al5O 12The above raw materials were weighed so as to achieve [the desired state]. Next, the weighed raw materials and alumina balls (10 mm in diameter) were put into a plastic pot. The amount of the alumina balls was such that it filled about 1 / 3 of the volume of the plastic pot. Then, pure water was put into the plastic pot, and using a pot rotation device (manufactured by Nitto Kagaku Co., Ltd., BALL MILL ANZ-51S), the raw materials and the pure water were mixed. This mixing was carried out for 12 hours. In this way, a slurry-like mixed raw material was obtained.

[0079] The slurry-like mixed raw material was dried using a dryer. Specifically, a nylon (Registered Trademark) sheet was laid so as to cover the inner wall of a metal vat, and the mixed raw material was poured above the nylon (Registered Trademark) sheet. The metal vat, the nylon (Registered Trademark) sheet, and the mixed raw material were treated in a dryer set at 150 °C for 8 hours and dried. Then, the dried mixed raw material was recovered, and the mixed raw material was granulated using a spray dryer device. Note that during granulation, polyvinyl alcohol was used as an adhesive (binder).

[0080] The granulated mixed raw material was temporarily molded into a cylindrical shape using an electro-hydraulic press (manufactured by Riken Seiki Co., Ltd., EMP-5) and a cylindrical mold (outer diameter 58 mm, inner diameter 38 mm, height 130 mm). The pressure during molding was set at 5 MPa / cm 2 Then, using a cold isostatic pressing device, the molded body after temporary molding was fully molded. The pressure during full molding was set at 300 MPa. Note that after full molding, a heat treatment (debinding treatment) was carried out for the purpose of removing the adhesive (binder) used during granulation. The temperature of the heat treatment was set at 500 °C. Also, the time of the heat treatment was set at 10 hours.

[0081] The molded body after heat treatment was fired using a tubular atmosphere furnace. The firing temperature was set at 1675 °C. Also, the firing time was set at 4 hours. The firing atmosphere was a mixed gas atmosphere of nitrogen and hydrogen. Note that the outer diameter and inner diameter of the fired product after firing were 43 mm and 29 mm, respectively.

[0082] The fired cylindrical fired product was sliced using a multi-wire saw. The thickness of the sliced cylindrical fired product was set to about 700 μm.

[0083] The sliced fired product was polished using a polishing device, and the thickness of the fired product was adjusted. By performing this adjustment, the fired product became a phosphor ceramic layer. The thickness of the phosphor ceramic layer was 53 μm in Example 1, 75 μm in Example 2, 106 μm in Example 3, and 206 μm in the comparative example.

[0084] The outer diameter and inner diameter of the phosphor ceramic layers according to Examples 1 to 3 and the comparative example were 43 mm and 29 mm, respectively. Further, the phosphor ceramic layers according to Examples 1 to 3 and the comparative example were dark yellow.

[0085] Subsequently, the evaluation of the phosphor ceramic layer will be described.

[0086] First, the density of the phosphor ceramic layers according to Examples 1 to 3 and the comparative example was evaluated using the Archimedes method. The density of the phosphor ceramic layers according to Examples 1 to 3 and the comparative example was all 4.49 g / cm 3 It was. Also, the density of the phosphor ceramic layers according to Examples 1 to 3 and the comparative example was all Y3Al5O 12 The theoretical density (4.55 g / cm 3 ) was 98.7%. That is, the density of the phosphor ceramic layers according to Examples 1 to 3 and the comparative example was all 97% or more and 100% or less of the theoretical density of Y3Al5O 12 .

[0087] Subsequently, a method for manufacturing a wavelength conversion device will be described.

[0088] First, a disk-shaped substrate body of Al (diameter 50 mm, thickness 0.5 mm) is prepared. Subsequently, using a dispenser device, on the substrate body 、T A silicone resin in which iO2 particles are dispersed toIt was applied so that the light-reflecting layer to be included becomes circular (outer diameter 46 mm, inner diameter 30 mm). Here, the silicone-based resin included in the light-reflecting layer also functions as an adhesive for bonding the phosphor ceramic layer and the substrate body.

[0089] Thereafter, the phosphor ceramic layer is arranged so as to overlap with the circularly applied light-reflecting layer. Here, the phosphor ceramic layer was fixed by a metal jig so that the thickness of the light-reflecting layer becomes about 50 μm. Thereafter, heat treatment was performed using a dryer to cure the light-reflecting layer. The temperature of the heat treatment at this time was 150 °C. The visible light reflectance of the light-reflecting surface, which is one surface included in the light-reflecting layer, was 95% or more.

[0090] In this way, the wavelength conversion devices according to Examples 1 to 3 and the comparative example, each including the phosphor ceramic layer according to the above Examples 1 to 3 and the comparative example and the substrate, were obtained.

[0091] Furthermore, the evaluation of the wavelength conversion device will be described.

[0092] Using an evaluation apparatus for a reflection-type laser excitation method wavelength conversion device, the wavelength conversion devices according to Examples 1 to 3 and the comparative example were evaluated. Specifically, in the evaluation apparatus, the rotated wavelength conversion device is irradiated with excitation light (laser light), and the fluorescence energy of the fluorescence emitted from the wavelength conversion device is evaluated by a power meter. The wavelength, output, and irradiation spot diameter (1 / e 2 ) of the laser light were 455 nm, 70 W, and 1.2 mm, respectively. This laser light is a Gaussian beam. Also, the rotation speed of the wavelength conversion device was 7200 rpm. The evaluation apparatus is provided with an aperture member that shields a part of the fluorescence emitted from the wavelength conversion device. At this time, for example, the distance between the wavelength conversion device and the aperture member is 3 mm or more and 100 mm or less, and the opening of the aperture member is a circular hole with an opening diameter of 5 mm or more and 10 mm or less.

[0093] FIG. 6 is a diagram showing the evaluation results of the wavelength conversion devices according to Examples 1 to 3 and Comparative Example of the present embodiment. Specifically, FIG. 6 shows the relative fluorescence energy values (after passing through the aperture), the relative fluorescence energy values (before passing through the aperture), and the coupling efficiency of the wavelength conversion devices according to Examples 1 to 3 and Comparative Example.

[0094] Here, the relative fluorescence energy value (after passing through the aperture) is the relative value of the fluorescence energy of the fluorescence emitted by each wavelength conversion device after passing through the aperture of the aperture member. Note that the fluorescence energy of the fluorescence emitted by the wavelength conversion device according to the Comparative Example after passing through the aperture was set to 100%.

[0095] Also, the relative fluorescence energy value (before passing through the aperture) is the relative value of the fluorescence energy of the fluorescence emitted by each wavelength conversion device before passing through the aperture of the aperture member. Note that the fluorescence energy of the fluorescence emitted by the wavelength conversion device according to the Comparative Example after passing through the aperture was set to 100%.

[0096] The coupling efficiency is the ratio of the relative fluorescence energy value (after passing through the aperture) to the relative fluorescence energy value (before passing through the aperture). That is, the coupling efficiency is the value obtained by dividing the relative fluorescence energy value (after passing through the aperture) by the relative fluorescence energy value (before passing through the aperture).

[0097] In a projector, the fluorescence after passing through the aperture is used as part of the projection light. That is, it can be said that the larger the relative fluorescence energy value (after passing through the aperture), the more fluorescence can be used as the projection light of the projector.

[0098] As shown in Fig. 6, the coupling efficiencies of the wavelength conversion devices according to Example 1, Example 2, Example 3 and the Comparative Example were 85%, 86%, 84% and 81% respectively. That is, the coupling efficiencies in the Examples were all higher than the coupling efficiency in the Comparative Example. The higher the coupling efficiency, the more light passing through the opening among the generated fluorescence, that is, as shown in Figs. 5A and 5B, it indicates that the emission area of the fluorescence emitted by the wavelength conversion device is small. That is, the emission area of the fluorescence emitted by the wavelength conversion devices according to Examples 1 to 3 is smaller than the emission area of the fluorescence emitted by the wavelength conversion device according to the Comparative Example, indicating that the wavelength conversion devices according to the Examples have high light utilization efficiency.

[0099] Also, as shown in Fig. 6, it is clear that when the thickness of the phosphor ceramic layer according to Examples 1 to 3 is in the range of 50 μm or more and 120 μm or less, a sufficiently high coupling efficiency is achieved compared with the Comparative Example. That is, when the thickness of the phosphor ceramic layer 20 according to the above-described embodiment is in the range of 50 μm or more and 120 μm or less, the wavelength conversion device 1 with high light utilization efficiency is realized.

[0100] Also, the relative fluorescence energy values (after passing through the opening) of the wavelength conversion devices according to Example 1, Example 2, Example 3 and the Comparative Example were 103%, 106%, 105% and 100% respectively. That is, in any of Examples 1 to 3, the relative fluorescence energy value (after passing through the opening) was higher than the relative fluorescence energy value (after passing through the opening) in the Comparative Example. And in Examples 1 to 3, the relative fluorescence energy values (after passing through the opening) of the wavelength conversion devices according to Example 2 with the phosphor ceramic layer thickness of 76 μm and Example 3 with the phosphor ceramic layer thickness of 106 μm were higher.

[0101] Also, as shown in FIG. 6, when the thickness of the phosphor ceramic layer according to Examples 2 and 3 is in the range of 70 μm or more and 120 μm or less, it is clear that a sufficiently high relative fluorescence energy value (after passing through the aperture) is obtained as compared with the comparative example. That is, when the thickness of the phosphor ceramic layer 20 according to the present embodiment is in the range of 70 μm or more and 120 μm or less, the wavelength conversion device 1 with higher light utilization efficiency is realized.

[0102] Furthermore, the relative fluorescence energy values (before passing through the aperture) of the wavelength conversion devices according to Example 1, Example 2, Example 3, and the comparative example were 121%, 124%, 125%, and 124%, respectively. The relative fluorescence energy value (before passing through the aperture) of the wavelength conversion device according to Example 1, in which the thickness of the phosphor ceramic layer was the thinnest at 53 μm, was lower than the relative fluorescence energy values (before passing through the aperture) of the wavelength conversion devices according to Example 2 and Example 3 and the comparative example. This reason is presumably that in the wavelength conversion device according to Example 1, since the thickness of the phosphor ceramic layer was thin, the phosphor ceramic layer could not sufficiently absorb the laser light.

[0103] Here, furthermore, in the wavelength conversion device according to Example 4 of the present embodiment, the manufacturing method and the light utilization efficiency will be described.

[0104] First, the manufacturing method of the phosphor ceramic layer included in the wavelength conversion device according to Example 4 of the present embodiment will be described.

[0105] All of the phosphor ceramic layers according to Example 4 are composed of a first crystal phase represented by (Y 0.997 Ce 0.003 )3Al5O 12 . Also, all of the phosphor ceramic layers according to Example 4 are composed of Ce 3+ activated phosphors.

[0106] In Example 4, a compound (Y 0.997 Ce 0.003 )3Al5O 12A fired product was obtained in the same procedure as in Examples 1 to 3, except that the raw materials were weighed so as to obtain the following composition. That is, the main difference between the phosphor ceramic layers according to Examples 1 to 3 and the phosphor ceramic layer according to Example 4 is that the composition ratio of Y and Ce is different.

[0107] The thickness of the phosphor ceramic layer according to Example 4 was 103 μm.

[0108] The outer diameter and inner diameter of the phosphor ceramic layer according to Example 4 were 41 mm and 27 mm, respectively. The phosphor ceramic layer according to Example 4 was dark yellow.

[0109] Next, the evaluation of the phosphor ceramic layer will be described.

[0110] First, the density of the phosphor ceramic layer according to Example 4 was evaluated using the Archimedes method. The density of the phosphor ceramic layer according to Example 4 was 4.48 g / cm 3 . Also, the densities of the phosphor ceramic layers according to Example 4 were all 98.4% of the theoretical density (4.55 g / cm 12 ) of Y3Al5O 3 . That is, the density of the phosphor ceramic layer according to Example 4 was 97% or more and 100% or less of the theoretical density of Y3Al5O 12 .

[0111] As described above, the phosphor ceramic layer 20 according to the present embodiment is composed of YAG having Ce 3+ and Ce 4+ . That is, the phosphor ceramic layer 20 contains Ce 3+ and Ce 4+ . Therefore, next, the Ce 3+ abundance ratio and the Ce 4+ abundance ratio of the phosphor ceramic layer according to Example 4 were evaluated using a hard X-ray XAFS apparatus. Specifically, using a hard X-ray XAFS apparatus, an XAFS spectrum of the phosphor ceramic layer according to Example 4 was obtained in the range of 5687 eV to 5777 eV. For this obtained XAFS spectrum, Ce3+ reference spectrum of 4+ and Ce 3+ abundance ratio and Ce 4+ abundance ratio were evaluated. Note that Ce 3+ reference spectrum of 4+ and Ce

[0112] Table 1 shows the Ce 3+ abundance ratio and Ce 4+ abundance ratio of the phosphor ceramic layer according to Example 4. As shown in Table 1, the Ce 3+ abundance ratio and Ce 4+ abundance ratio of the phosphor ceramic layer according to Example 4 were 78.3% and 21.7%, respectively. In the phosphor ceramic layer according to Example 4, Ce 3+ ×100% / (Ce 3+ +Ce 4+ )≧60% was satisfied, that is, the Ce 3+ abundance ratio was 60% or more.

[0113]

Table 1

[0114] Subsequently, a method for manufacturing the wavelength conversion device according to Example 4 will be described.

[0115] First, a disk-shaped substrate body made of Al coated with Ag as a light reflection layer (diameter 50 mm, thickness 0.5 mm) is prepared. A screw hole is opened at the center of this substrate body. Subsequently, a phosphor ceramic layer is provided on this substrate body.

[0116] Inside the phosphor ceramic layer, a disk-shaped first plate member made of Al with a screw hole in the center (outer diameter 26.5 mm, thickness 100 μm) is installed. Note that the phosphor ceramic layer is a phosphor ring, and the first plate member is installed inside the ring shape. And further, a disk-shaped second plate member made of Al with a screw hole in the center (outer diameter 29 mm, thickness 200 μm) is installed so as to overlap the phosphor ceramic layer and the first plate member. Then, the substrate body, the first plate member, and the second plate member are screwed together. In this way, the phosphor ceramic layer is fixed, and a wavelength conversion device is obtained. That is, in the wavelength conversion device according to Example 4, the phosphor ceramic layer is sandwiched and fixed between the substrate body and the second plate member.

[0117] In this way, the phosphor ceramic layer and the wavelength conversion device according to Example 4 were obtained.

[0118] Furthermore, the evaluation of the wavelength conversion device will be described.

[0119] The wavelength conversion device according to Example 4 was evaluated in the same manner as in Examples 1 to 3.

[0120] FIG. 7 is a diagram showing the evaluation results of the wavelength conversion device according to Example 4 of the present embodiment. Specifically, in FIG. 7, the relative fluorescence energy value (after passing through the opening), the relative fluorescence energy value (before passing through the opening), and the coupling efficiency of the wavelength conversion device according to Example 4 are shown. Note that in FIG. 7, for comparison, the relative fluorescence energy value (after passing through the opening), the relative fluorescence energy value (before passing through the opening), and the coupling efficiency of the wavelength conversion devices according to Examples 1 to 3 and the comparative example are also shown.

[0121] Here, the relative fluorescence energy value (after passing through the opening) is the relative value of the fluorescence energy of the fluorescence emitted by the wavelength conversion device after passing through the opening of the aperture member. Note that the fluorescence energy of the fluorescence emitted by the wavelength conversion device according to the comparative example after passing through the opening was set to 100%.

[0122] The relative fluorescence energy value (before passing through the opening) is the relative value of the fluorescence energy of the wavelength conversion device before passing through the opening of the aperture member. Note that the fluorescence energy of the wavelength conversion device according to the comparative example after passing through the opening is set to 100%.

[0123] The coupling efficiency is the ratio of the relative fluorescence energy value (after passing through the opening) to the relative fluorescence energy value (before passing through the opening). That is, the coupling efficiency is the value obtained by dividing the relative fluorescence energy value (after passing through the opening) by the relative fluorescence energy value (before passing through the opening).

[0124] As shown in FIG. 7, the coupling efficiency of the wavelength conversion device according to Example 4 was 85%. Also, as described above, the coupling efficiency of the wavelength conversion device according to the comparative example is 81%. The wavelength conversion device according to Example 4, which has a higher coupling efficiency, has more light passing through the opening among the generated fluorescence and a smaller fluorescence emission area. For example, as shown in FIGS. 5A and 5B, in the wavelength conversion device according to Example 4, since a large amount of light passes through the opening 2a of the aperture member 2, there is a large amount of light that can be used as the projection light of the projector 100. That is, the wavelength conversion device according to Example 4 shows high light utilization efficiency.

[0125] Furthermore, the relative fluorescence energy value (after passing through the opening) and the relative fluorescence energy value (before passing through the opening) of the wavelength conversion device according to Example 4 were 108% and 128%, respectively. These values are higher than the relative fluorescence energy value (after passing through the opening) and the relative fluorescence energy value (before passing through the opening) of the wavelength conversion devices according to Examples 1 to 3.

[0126] As described above, in the phosphor ceramic layer according to Example 4, the Ce 3+ abundance ratio is 60% or more, and the Ce 4+ abundance ratio is less than 40% and is small. Therefore, since the non-radiative relaxation loss due to Ce 4+ is reduced, Ce 3+The phosphor ceramic layer according to Example 4 with a ratio of 60% or more has high luminous efficiency. Therefore, by providing such a phosphor ceramic layer, the wavelength conversion device according to Example 4 can improve the utilization efficiency of light. Furthermore, when a projector is provided with such a wavelength conversion device 1, the utilization efficiency of the light of the projector can be improved. For example, a projector with low power consumption can be realized.

[0127] Also, since the non-radiative relaxation loss by Ce 4+ is reduced, the heat generation of the phosphor ceramic layer according to Example 4 is reduced. For this reason, in a projector provided with such a phosphor ceramic layer, the maximum input energy of the excitation light L1 can be increased, that is, a high-output projector can be realized.

[0128] (Modification 1) The phosphor ceramic layer 20 according to the embodiment is composed only of the first crystal phase, but is not limited thereto. Here, a wavelength conversion device 1a provided with a phosphor ceramic layer 20a including the first crystal phase and the second crystal phase will be described.

[0129] [Configuration of Wavelength Conversion Device] First, the configuration of the wavelength conversion device 1a according to this modification will be described with reference to the drawings. FIG. 8 is a perspective view of the wavelength conversion device 1a according to this modification. FIG. 9 is a cross-sectional view showing a cross-section of the wavelength conversion device 1a taken along line IX-IX of FIG. 8.

[0130] The wavelength conversion device 1a according to this modification has the same configuration as the wavelength conversion device 1 according to the embodiment, except that it includes a phosphor ceramic layer 20a. That is, as shown in FIGS. 8 and 9, the wavelength conversion device 1a includes a substrate 10 having a light reflecting surface 13, a phosphor ceramic layer 20a, and an antireflection layer 30.

[0131] Note that also in this modification, the wavelength conversion device 1a is a phosphor wheel used in a projector, which receives the excitation light L1 and emits reflected light including fluorescence.

[0132] The phosphor ceramic layer 20a includes a first crystal phase and a second crystal phase. More specifically, in this modification, the phosphor ceramic layer 20a is composed of a first crystal phase and a second crystal phase.

[0133] The first crystal phase has the configuration as described in the embodiment.

[0134] Also, the second crystal phase is a crystal phase having a structure different from the garnet structure. That is, the second crystal phase has a structure different from the structure of the first crystal phase. For this reason, the refractive index of the first crystal phase and the refractive index of the second crystal phase are different from each other.

[0135] When the phosphor ceramic layer 20a is observed in cross section, when the entire area of the image showing the phosphor ceramic layer 20a is taken as 100%, the area showing the first crystal phase is, for example, 10% or more and 99% or less. Note that the area showing the first crystal phase is not limited to this, and may be, for example, 75% or more and 98% or less, or 85% or more and 95% or less. That is, the phosphor ceramic layer 20a according to this modification mainly contains the first crystal phase.

[0136] As an example, the second crystal phase according to this modification is a crystal phase having a perovskite structure, but is not limited to this, and may be a crystal phase having a structure different from the garnet structure and the perovskite structure.

[0137] The perovskite structure is a crystal structure represented by the general formula EFO3. For the element E, rare earth elements such as Ca, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Lu are applicable, and for the element F, elements such as Mg, Al, Si, Ga, and Sc are applicable. Examples of such a garnet structure include YAP (Yttrium Aluminum Perovskite). In this modification, the second crystal phase is (Y 1-y Ce y)AlO3 (0 ≦ y < 0.1), that is, it is represented by YAP.

[0138] Note that the second crystal phase may be a solid solution of a plurality of perovskite crystal phases with different chemical compositions.

[0139] Also, the second crystal phase may contain a crystal phase with a chemical composition shifted from the crystal phase represented by the general formula EFO3 described above.

[0140] Note that the phosphor ceramic layer 20a according to this modification is composed only of the first crystal phase and the second crystal phase, that is, it does not contain a crystal phase having a structure different from the garnet structure and the perovskite structure.

[0141] In this modification, as an example, the material representing the second crystal phase is YAP, but it is not limited to this. Also, the difference between the refractive index of the material representing the second crystal phase and the refractive index of the material representing the first crystal phase having a garnet structure (here YAG) is preferably 0.05 or more and 0.5 or less, so that the material representing the second crystal phase is selected. Thereby, as described above, the refractive index of the first crystal phase and the refractive index of the second crystal phase become different from each other. Note that the difference between the refractive index of the material representing the second crystal phase and the refractive index of the material representing the first crystal phase is more preferably 0.06 or more and 0.3 or less, and even more preferably 0.07 or more and 0.15 or less.

[0142] Also, for example, when the second crystal phase according to this modification is a crystal phase having a structure different from the garnet structure and the perovskite structure, as the material representing the second crystal phase, Al2O3, Y2O3, Y4Al2O9, Lu2O3, Lu4Al2O9, etc. may be used.

[0143] The phosphor ceramic layer 20a receives the light incident from above the wavelength conversion device 1a as the excitation light L1 and emits fluorescence. More specifically, when the light emitted from the excitation light source described later is irradiated onto the phosphor ceramic layer 20a as the excitation light L1, fluorescence is emitted from the phosphor ceramic layer 20a as wavelength-converted light. That is, the wavelength-converted light emitted from the phosphor ceramic layer 20a is light having a wavelength longer than the wavelength of the excitation light L1.

[0144] In this modified example, the wavelength-converted light emitted from the phosphor ceramic layer 20a includes fluorescence that is yellow light. The phosphor ceramic layer 20a, for example, absorbs light having a wavelength of 380 nm or more and 490 nm or less, and emits fluorescence that is yellow light having a fluorescence peak wavelength in the region of 490 nm or more and 580 nm or less. By configuring the phosphor ceramic layer 20a with YAG and YAP, a phosphor ceramic layer 20a that easily emits fluorescence having a fluorescence peak wavelength in the region of 490 nm or more and 580 nm or less is realized.

[0145] The x coordinate of the chromaticity diagram of the wavelength-converted light emitted from the phosphor ceramic layer 20a may be 0.415 or less, more preferably 0.410 or less, and even more preferably 0.408 or less. When the x coordinate of the chromaticity diagram of the wavelength-converted light emitted from the phosphor ceramic layer 20a is the above numerical value, the temperature quenching of the phosphor ceramic layer 20a is reduced, so that a phosphor ceramic layer 20a with high luminous efficiency can be realized.

[0146] The density of the phosphor ceramic layer 20a may be 95% or more and 100% or less of the theoretical density, and more preferably 97% or more and 100% or less of the theoretical density. Here, the theoretical density is the density when the atoms in the layer are ideally arranged. In other words, the theoretical density is the density assuming that there are no voids in the phosphor ceramic layer 20a, and it is a value calculated using the crystal structure. For example, when the density of the phosphor ceramic layer 20a is 99%, the remaining 1% corresponds to voids. That is, the higher the density of the phosphor ceramic layer 20a, the fewer the voids. When the density of the phosphor ceramic layer 20a is within the above range, the total fluorescence emitted by the phosphor ceramic layer 20a increases, so that a wavelength conversion device 1a and a projector that emit more light can be provided. Note that the theoretical density is the theoretical density of the first crystal phase having a garnet structure.

[0147] The density of the phosphor ceramic layer 20a may be 4.32 g / cm 3 or more and 4.55 g / cm 3 or less, and more preferably 4.41 g / cm 3 or more and 4.55 g / cm 3 or less. As shown in this modification, when the phosphor ceramic layer 20a is composed of YAG and YAP, when the density of the phosphor ceramic layer 20a is within the above range, the density of the phosphor ceramic layer 20a is 95% or more and 100% or less and 97% or more and 100% or less, respectively. When the density of the phosphor ceramic layer 20a is within the above range, the excitation light L1 absorbed by the phosphor ceramic layer 20a can be efficiently converted into fluorescence. That is, a phosphor ceramic layer 20a with high luminous efficiency is realized.

[0148] The film thickness (length in the z-axis direction) of the phosphor ceramic layer 20a is preferably 50 μm or more and less than 150 μm, and more preferably 50 μm or more and less than 120 μm. Further, the film thickness of the phosphor ceramic layer is more preferably 70 μm or more and less than 120 μm, and even more preferably 80 μm or more and less than 110 μm.

[0149] [Configuration of Projector] The wavelength conversion device 1a configured as described above is used in a projector, similarly to the wavelength conversion device 1 according to the embodiment. That is, instead of the wavelength conversion device 1 according to the embodiment, the wavelength conversion device 1a according to this modification example may be used.

[0150] [Examples] Here, in the wavelength conversion devices according to Examples 5 and 6, the manufacturing method and the light utilization efficiency will be described. Note that the wavelength conversion device according to Example 5 has the same configuration as the wavelength conversion device 1a according to this modification example, and the wavelength conversion device according to Example 6 has the same configuration as the wavelength conversion device 1 according to the embodiment.

[0151] First, the manufacturing method of the phosphor ceramics layer included in the wavelength conversion devices according to Examples 5 and 6 will be described.

[0152] The phosphor ceramics layer according to Example 5 is mainly composed of a crystal phase represented by (Y 0.997 Ce 0.003 )3Al5O 12 (that is, the first crystal phase). As described above, the phosphor ceramics layer according to Example 5 also includes the second crystal phase. The phosphor ceramics layer according to Example 6 is composed of a crystal phase represented by (Y 0.997 Ce 0.003 )3Al5O 12 (that is, the first crystal phase). Also, the phosphor ceramics layers according to Examples 5 and 6 are both composed of Ce 3+ - activated phosphors.

[0153] The phosphor ceramics layers according to Examples 5 and 6 used the same raw materials as those used in Examples 1 to 3.

[0154] First, the raw materials were weighed so as to form a compound (Y 0.997 Ce 0.003 )3Al5O 12 with a stoichiometric composition. Next, the raw materials were mixed in the same procedure as in Examples 1 to 3 to obtain a slurry - like mixed raw material.

[0155] Next, in Example 5, granulated mixed raw materials were obtained by a method that does not use a spray dryer. Specifically, 100 g of the mixed raw materials dried using a dryer were put into an alumina mortar. Then, 0.5 w t % of an aqueous solution of polyvinyl alcohol dissolved was used as the polyvinyl alcohol solution, and 18 mL of this polyvinyl alcohol solution was further put into the alumina mortar. Thereafter, using a pestle, the mixed raw materials and the polyvinyl alcohol solution were mixed. Next, the mixture of the mixed raw materials and the polyvinyl alcohol solution was sieved using a mesh with an opening of 512 μm. As a result, a mixture of the mixed raw materials and the polyvinyl alcohol solution with a particle size of about 512 μm or less was obtained. Thereafter, the mixture was treated in a dryer set at 105°C for 30 minutes to remove moisture. In this way, the granulated mixed raw materials used in Example 5 were obtained. Also, in Example 6, the mixed raw materials were granulated in the same procedure as in Examples 1 to 3, and granulated mixed raw materials were obtained.

[0156] The phosphor ceramic layers according to Examples 5 and 6 were preformed in the same manner. Specifically, the granulated mixed raw materials were preformed into a cylindrical shape using an electrohydraulic press (manufactured by Riken Seiki Co., Ltd., EMP-5) and a cylindrical mold (outer diameter 66 mm, inner diameter 46 mm, height 130 mm). The pressure during molding was 5 MPa. Next, using a cold isostatic pressing device, the preformed molded body was fully molded. The pressure during full molding was 300 MPa. Note that the molded body after full molding was subjected to a heat treatment (debinder treatment) for the purpose of removing the adhesive (binder) used during granulation. The temperature of the heat treatment was 500°C. Also, the time of the heat treatment was 10 hours.

[0157] The molded body after the heat treatment was fired using a tubular atmosphere furnace. The firing temperature was 1675°C. Also, the firing time was 4 hours. The firing atmosphere was a mixed gas atmosphere of nitrogen and hydrogen. Note that the outer diameter and inner diameter of the fired product after firing were 49 mm and 35 mm, respectively.

[0158] The cylindrical fired product after firing was sliced using a multi-wire saw. The thickness of the sliced cylindrical fired product was set to about 700 μm.

[0159] In Examples 5 and 6, the fired product after firing was heat-treated at a temperature of 1000 °C or higher.

[0160] Using a polishing device, the fired product after slicing was polished to adjust the thickness of the fired product. The thickness of the phosphor ceramic layer was 118 μm in Example 5 and 117 μm in Example 6.

[0161] Note that the outer diameter and inner diameter of the phosphor ceramic layer according to Examples 5 and 6 were both 49 mm and 35 mm. Also, the phosphor ceramic layer according to Examples 5 and 6 was dark yellow.

[0162] Subsequently, the evaluation of the phosphor ceramic layer will be described.

[0163] First, using the Archimedes method, the densities of the phosphor ceramic layers according to Examples 5 and 6 were evaluated. The densities of the phosphor ceramic layers according to Examples 5 and 6 were 4.48 g / cm 3 and 4.42 g / cm 3 respectively. Also, the densities of the phosphor ceramic layers according to Examples 5 and 6 were 98.4% and 97.1% of the theoretical density (4.55 g / cm3) of Y3Al5O 12 respectively. That is, the densities of the phosphor ceramic layers according to Examples 5 and 6 were 97% or more and 100% or less of the theoretical density of Y3Al5O 12

[0164] Next, using a scanning electron microscope (SEM), the cross-sectional SEM image of the phosphor ceramic layer according to Example 5 was evaluated.

[0165] ​FIG. 10 is an SEM image showing a cross-section of the phosphor ceramic layer according to Example 5 of this modified example. FIG. 10(a) is an SEM image showing a wide-range cross-section of the phosphor ceramic layer according to Example 5. Note that the SEM image shown in FIG. 10(a) corresponds to the image of the region surrounded by the dashed rectangle in the cross-sectional view shown in FIG. 9. FIG. 10(b) is an enlarged SEM image of the region surrounded by the dashed rectangle in FIG. 10(a). FIG. 10(c) is an enlarged SEM image of the region surrounded by the two-dashed rectangle in FIG. 10(a).

[0166] Here, the phosphor ceramic layer in Example 5, that is, the phosphor ceramic layer 20a according to this modified example, includes a single-phase part and a mixed-phase part separated from this single-phase part. The single-phase part is shown in FIG. 10(b), and the mixed-phase part is shown in FIG. 10(c).

[0167] In this modified example, in the SEM image in FIG. 10, the darker-colored region corresponds to the first crystal phase having a garnet structure, and the lighter-colored region corresponds to the second crystal phase having a perovskite structure. Also, in the SEM image in FIG. 10, the darkest-colored region corresponds to voids.

[0168] Only the first crystal phase is provided in the single-phase part among the first crystal phase having a garnet structure and the second crystal phase having a structure different from the garnet structure (here, a perovskite structure). More specifically, here, only the first crystal phase is provided in the single-phase part, and no other crystal phases having a structure different from the garnet structure and the perovskite structure are provided.

[0169] Also, both the first crystal phase and the second crystal phase are mixed and provided in the mixed-phase part. More specifically, only both the first crystal phase and the second crystal phase are mixed and provided in the mixed-phase part. Note that both the first crystal phase and the second crystal phase, and further other crystal phases having a structure different from the garnet structure and the perovskite structure may be mixed and provided in the mixed-phase part.

[0170] The mixed-phase part according to Example 5 is provided with a structure in which both the first crystal phase and the second crystal phase are randomly intertwined, but it is not limited thereto, and both the first crystal phase and the second crystal phase may be provided with a structure in which they are periodically arranged.

[0171] Note that the phosphor ceramic layer in Example 5 includes a plurality of mixed-phase parts. The regions surrounded by the dotted lines in Fig. 10(a) correspond to the mixed-phase parts, respectively.

[0172] The periphery of each of the plurality of mixed-phase parts is surrounded by a single-phase part. The shapes of the single-phase part and the plurality of mixed-phase parts can also be said to be an island-in-sea shape. In this case, the single-phase part corresponds to the sea and the plurality of mixed-phase parts correspond to the islands.

[0173] In addition, more second crystal phase may be provided in the mixed-phase part than the first crystal phase. For example, the ratio of the first crystal phase to the second crystal phase in the mixed-phase part is as follows. When the phosphor ceramic layer according to Example 5 is observed in cross section (for example, Fig. 10), when the entire area of the image showing the mixed-phase part is 100%, the area showing the second crystal phase is, for example, 10% or more and 99% or less. Note that the area showing the second crystal phase is not limited thereto, and may be, for example, 70% or more and 95% or less, or 80% or more and 90% or less. That is, mainly the second crystal phase is provided in the mixed-phase part according to this modification.

[0174] As described above, both the first crystal phase having a garnet structure and the second crystal phase having a perovskite structure are mixed and provided in the mixed-phase part. As described above, the refractive index of the first crystal phase and the refractive index of the second crystal phase are different from each other. Therefore, the refractive index of the single-phase part provided with only the first crystal phase and the refractive index of the mixed-phase part are different from each other. In this modification, since the refractive index of YAG is 1.83 and the refractive index of YAP is 1.91, the refractive index of the single-phase part is lower than the refractive index of the mixed-phase part.

[0175] Furthermore, the size of the mixed-phase portion will be described. Note that the size of the mixed-phase portion refers to the length in the longitudinal direction of the mixed-phase portion in the SEM image shown in FIG. 10. The size of the mixed-phase portion is, for example, the length indicated by the double-headed arrows in FIG. 10. The size of the mixed-phase portion is preferably 0.5 μm or more and less than 500 μm, more preferably 1 μm or more and less than 300 μm, and even more preferably 2 μm or more and less than 100 μm.

[0176] Thus, it was shown that the phosphor ceramic layer (phosphor ceramic layer 20a) according to Example 5 contains the first crystal phase and the second crystal phase, and a single-phase portion and a mixed-phase portion are provided in FIG. 10. On the other hand, the phosphor ceramic layer according to Example 6 is composed of only the first crystal phase. Therefore, it has been confirmed that no mixed-phase portion is provided in the phosphor ceramic layer according to Example 6.

[0177] Subsequently, a method for manufacturing the wavelength conversion device according to Examples 5 and 6 will be described.

[0178] First, a disk-shaped substrate body (diameter: 50 mm, thickness: 0.5 mm) of Al coated with Ag as a light reflection layer is prepared. A screw hole is formed in the central portion of this substrate body. Subsequently, a phosphor ceramic layer is installed on this substrate body.

[0179] An Al disk-shaped third plate member (outer diameter: 34.5 mm, thickness: 100 μm) having a screw hole in the central portion is installed inside the phosphor ceramic layer. Note that the phosphor ceramic layer is a phosphor ring, and the third plate member is installed inside the ring shape. Then, an Al disk-shaped fourth plate member (outer diameter: 39 mm, thickness: 200 μm) having a screw hole in the central portion is installed so as to overlap the phosphor ceramic layer and the third plate member. Then, the substrate body, the third plate member, and the fourth plate member are screwed together. In this way, the phosphor ceramic layer is fixed, and a wavelength conversion device is obtained. That is, in the wavelength conversion device according to Examples 5 and 6, the phosphor ceramic layer is sandwiched and fixed between the substrate body and the fourth plate member.

[0180] Furthermore, the evaluation of the wavelength conversion device will be described.

[0181] The wavelength conversion devices according to Examples 5 and 6 were evaluated in the same manner as in Examples 1 to 3.

[0182] FIG. 11 is a diagram showing the evaluation results of the wavelength conversion devices according to Examples 5 and 6 of this modified example. Specifically, FIG. 11 shows the relative fluorescence energy values (after passing through the aperture), the relative fluorescence energy values (before passing through the aperture), and the coupling efficiency of the wavelength conversion devices according to Examples 5 and 6.

[0183] Here, the relative fluorescence energy value (after passing through the aperture) is the relative value of the fluorescence energy of the fluorescence emitted by each wavelength conversion device after passing through the aperture of the aperture member. Note that the fluorescence energy of the fluorescence emitted by the wavelength conversion device according to Example 6 after passing through the aperture was set to 100%.

[0184] Also, the relative fluorescence energy value (before passing through the aperture) is the relative value of the fluorescence energy of the fluorescence emitted by each wavelength conversion device before passing through the aperture of the aperture member. Note that the fluorescence energy of the fluorescence emitted by the wavelength conversion device according to Example 6 after passing through the aperture was set to 100%.

[0185] Also, the coupling efficiency is the ratio of the relative fluorescence energy value (after passing through the aperture) to the relative fluorescence energy value (before passing through the aperture). That is, the coupling efficiency is the value obtained by dividing the relative fluorescence energy value (after passing through the aperture) by the relative fluorescence energy value (before passing through the aperture).

[0186] As shown in FIG. 11, the relative fluorescence energy values (after passing through the aperture) of the wavelength conversion devices according to Examples 5 and 6 were 101% and 100%, respectively. Furthermore, the relative fluorescence energy values (before passing through the aperture) of the wavelength conversion devices according to Examples 5 and 6 were 117% and 122%, respectively.

[0187] Also, the coupling efficiency of the wavelength conversion device according to Example 5 corresponding to the wavelength conversion device 1a according to this modification was 87%. The coupling efficiency of the wavelength conversion device according to Example 6 corresponding to the wavelength conversion device 1 according to the embodiment was 82%.

[0188] As described above, the phosphor ceramics layer (phosphor ceramics layer 20a) included in the wavelength conversion device according to Example 5 is composed of a first crystal phase and a second crystal phase having different refractive indexes from each other.

[0189] As a result, regions with different refractive indexes are generated in the phosphor ceramics layer 20a, making it easier for the excitation light L1 and fluorescence to be scattered. As a result, the light guiding in the planar direction of the layer (that is, the x-axis direction or the y-axis direction) shown in FIGS. 5A and 5B of the embodiment is suppressed, and the light emitting area of the phosphor ceramics layer 20a becomes smaller. For this reason, the coupling efficiency of the wavelength conversion device according to Example 5 is higher than that of the wavelength conversion device according to Example 6. That is, a wavelength conversion device (wavelength conversion device 1a) according to Example 5 with a smaller étendue and higher light utilization efficiency is realized. When a projector is equipped with such a wavelength conversion device 1a, the light utilization efficiency of the projector can be further increased.

[0190] Further, the phosphor ceramics layer 20a includes a single-phase portion and a mixed-phase portion separated from this single-phase portion. Only the first crystal phase out of the first crystal phase and the second crystal phase is provided in the single-phase portion, and both the first crystal phase and the second crystal phase are mixed and provided in the mixed-phase portion. The refractive indexes of such a single-phase portion and a mixed-phase portion are different from each other.

[0191] As a result, regions with different refractive indexes are generated in the phosphor ceramics layer 20a, making it even easier for the excitation light L1 and fluorescence to be scattered. As a result, the light emitting area of the phosphor ceramics layer 20a becomes even smaller. For this reason, a wavelength conversion device 1a with an even smaller étendue and higher light utilization efficiency is realized.

[0192] In addition, when the size of the mixed-phase portion is within the above range, the excitation light L1 and fluorescence are more likely to be scattered.

[0193] Further, the phosphor ceramic layer 20a includes a plurality of mixed-phase portions. The periphery of each of the plurality of mixed-phase portions is surrounded by a single-phase portion.

[0194] As a result, the excitation light L1 and fluorescence are more likely to be scattered. As a result, the light-emitting area of the phosphor ceramic layer 20a becomes even smaller. For this reason, the etendue is even smaller, and a wavelength conversion device 1a with even higher light utilization efficiency is realized.

[0195] The above results suggest that the coupling efficiency of the wavelength conversion device 1a has been increased not only by the light guiding suppression effect due to the thin film thickness of the phosphor ceramic layer 20a, but also by the light guiding suppression effect of the phosphor ceramic layer 20a itself. That is, it is suggested that the coupling efficiency of the wavelength conversion device 1a can be increased without controlling the film thickness of the phosphor ceramic layer 20a.

[0196] In addition, the difference between the refractive index of the material representing the second crystal phase and the refractive index of the material representing the first crystal phase is 0.05 or more and 0.5 or less.

[0197] As a result, the excitation light L1 and fluorescence are more likely to be scattered. As a result, the light-emitting area of the phosphor ceramic layer 20a becomes even smaller. For this reason, the etendue is even smaller, and a wavelength conversion device 1a with even higher light utilization efficiency is realized.

[0198] In addition, the second crystal phase is a crystal phase represented by (Y 1-y Ce y )AlO3 (0 ≦ y < 0.1).

[0199] This makes it easy to set the difference between the refractive index of the material representing the second crystal phase and the refractive index of the material representing the first crystal phase within the above range.

[0200] (Modification 2) Furthermore, a phosphor ceramic layer 20b with a different configuration will be described with respect to the phosphor ceramic layers 20 and 20a.

[0201] FIG. 12 is a perspective view of a phosphor ceramic member according to this modification.

[0202] As an example, the phosphor ceramic member according to this modification is a phosphor ceramic layer 20b having a layered shape.

[0203] The phosphor ceramic layer 20b is a member used in a projector, similar to the phosphor ceramic layers 20 and 20a shown in the embodiment and Modification 1.

[0204] The phosphor ceramic layer 20b has the same configuration as the phosphor ceramic layer 20a according to Modification 1, except for the following one point. Specifically, the one point is that the Ce 3+ abundance ratio is 60% or more.

[0205] That is, the phosphor ceramic layer 20b includes a first crystal phase having a garnet structure and a second crystal phase having a structure other than the garnet structure. The first crystal phase and the second crystal phase have different refractive indices from each other. In this modification, the first crystal phase and the second crystal phase are crystal phases represented by YAG and YAP, respectively, and the phosphor ceramic layer 20b mainly includes the first crystal phase. Also, the density of the phosphor ceramic member (phosphor ceramic layer 20b) may be 95% or more and 100% or less of the theoretical density, and more preferably 97% or more and 100% or less of the theoretical density. Also, the film thickness of the phosphor ceramic member (phosphor ceramic layer 20b) does not particularly need to be limited, but when limited, it is preferably 50 μm or more and less than 500 μm, more preferably 50 μm or more and less than 300 μm. Further, the film thickness is even more preferably 50 μm or more and less than 120 μm.

[0206] The phosphor ceramic member (phosphor ceramic layer 20b) has the above configuration. Therefore, when the phosphor ceramic layer 20b is used in a projector and excited light is irradiated, regions with different refractive indices are generated in the phosphor ceramic layer 20b, so that the excited light and fluorescence are more scattered. As a result, the light guiding in the plane direction of the layer (that is, the x-axis direction or the y-axis direction) shown in FIGS. 5A and 5B of the embodiment is suppressed, and the light emitting area of the phosphor ceramic layer 20b becomes smaller. For this reason, the phosphor ceramic member has a smaller etendue and higher light utilization efficiency. When a projector includes such a phosphor ceramic member (phosphor ceramic layer 20b), the light utilization efficiency of the projector can be further increased.

[0207] Furthermore, the phosphor ceramic layer 20b is composed of YAG and YAP containing Ce 3+ and Ce 4+ , that is, the phosphor ceramic layer 20b contains Ce 3+ and Ce 4+ . Here, in the phosphor ceramic layer 20b, Ce 3+ ×100% / (Ce 3+ +Ce 4+ )≧60% is satisfied, that is, the abundance ratio of Ce 3+ is 60% or more.

[0208] For the phosphor ceramic layer 20b with the abundance ratio of Ce 3+ being 60% or more, the non-radiative relaxation loss due to Ce 4+ is reduced, so the luminous efficiency is increased. Furthermore, in a projector including such a phosphor ceramic layer 20b, the light utilization efficiency can be increased. For example, a projector with low power consumption can be realized.

[0209] Also, since the non-radiative relaxation loss due to Ce 4+ is reduced, the heat generation of the phosphor ceramic layer 20b is reduced. For this reason, in a projector including such a phosphor ceramic layer 20b, the maximum input energy of the excitation light can be increased, that is, a high-output projector can be realized.

[0210] (Other embodiments) As described above, the wavelength conversion device and the like according to the present invention have been described based on embodiments and modification examples. However, the present invention is not limited to these embodiments and modification examples. As long as the gist of the present invention is not deviated from, various modifications conceived by those skilled in the art applied to the embodiments and modification examples, and other forms constructed by combining some constituent elements in the embodiments and modification examples are also included in the scope of the present invention.

[0211] In the embodiment, the light source is half was a semiconductor laser light source, but it is not limited to this off, L and it may be an ED light source.

[0212] Also, various changes, replacements, additions, omissions, etc. can be made to the above embodiments within the scope of the claims or their equivalents.

Description of reference numerals

[0213] 1 Wavelength conversion device 10 Substrate 11 Substrate body 12 Light reflection layer 13 Light reflection surface 20 Phosphor ceramic layer 30 Anti-reflection layer 100 Projector 121 Light-scattering particles L1 Excitation light L2 Reflected light

Claims

1. A wavelength conversion device used in a projector, which receives excitation light and emits reflected light including fluorescence, comprising: a substrate having a substrate body and a light reflection layer located above the substrate body and including a light reflection surface; a phosphor ceramic layer located above the light reflection surface and including a first crystal phase having a garnet structure; a bonding layer made of a transparent material provided between the light reflection layer and the phosphor ceramic layer; the visible light reflectivity of the light reflection surface is 95% or more and 100% or less; the density of the phosphor ceramic layer is 97% or more and 100% or less of the theoretical density; the film thickness of the phosphor ceramic layer is 50 μm or more and less than 120 μm; in plan view of the light reflection layer, the light reflection layer is provided to extend outside the outer shape of the phosphor ceramic layer; the phosphor ceramic layer further includes a second crystal phase having a structure different from the garnet structure; the second crystal phase has a randomly intertwined structure wavelength conversion device.

2. The film thickness of the phosphor ceramic layer is 70 μm or more and less than 120 μm The wavelength conversion device according to claim 1.

3. Furthermore, it includes an antireflection layer located above the phosphor ceramic layer for preventing reflection of the excitation light The wavelength conversion device according to claim 1 or 2.

4. The light reflection layer includes light-scattering particles The wavelength conversion device according to claim 1.

5. The light reflection layer contains Ag The wavelength conversion device according to claim 1.

6. The phosphor ceramic layer is composed of the first crystal phase represented by (Y １－ｘ Ce ｘ ), ３ Al ５ O １２ (0.001 ≤ x < 0.1). The wavelength conversion device according to any one of claims 1 to 5.

7. The density of the phosphor ceramic layer is 4.41 g / cm ３ or more and 4.55 g / cm ３ or less The wavelength conversion device according to any one of claims 1 to 6.

8. The phosphor ceramic layer includes a single-phase part and a mixed-phase part separated from the single-phase part, only the first crystal phase of the first crystal phase and the second crystal phase is provided in the single-phase part, both the first crystal phase and the second crystal phase are mixed and provided in the mixed-phase part The wavelength conversion device according to claim 1.

9. The phosphor ceramic layer includes a plurality of the mixed-phase parts, the periphery of each of the plurality of mixed-phase parts is surrounded by the single-phase part The wavelength conversion device according to claim 8.

10. The difference between the refractive index of the material representing the second crystal phase and the refractive index of the material representing the first crystal phase is 0.05 or more and 0.5 or less The wavelength conversion device according to claim 8 or 9.

11. The second crystal phase is (Y １－ｙ Ce ｙ )AlO ３ which is a crystal phase represented by (0 ≤ y < 0.1). The wavelength conversion device according to any one of claims 8 to 10.

12. The phosphor ceramic layer contains Ce ３＋ and Ce ４＋ and includes Ce ３＋ × 100% / (Ce ３＋ + Ce ４＋ ) ≥ 60% is satisfied The wavelength conversion device according to any one of claims 1 to 11.

13. An excitation light source that emits excitation light, The wavelength conversion device according to any one of claims 1 to 12, which receives the excitation light emitted from the excitation light source and emits reflected light including fluorescence, and A projector.

Images