Wavelength conversion element

Abstract

A first wavelength conversion element according to an embodiment of the present disclosure includes: a phosphor layer; a coolant; a coolant delivery component and a housing. The phosphor layer includes a plurality of phosphor particles. The phosphor layer has voids therein. The coolant cools the phosphor layer. The coolant delivery component is disposed in contact with the phosphor layer. The coolant delivery component circulates the coolant. The housing encapsulates the phosphor layer, the coolant and the coolant delivery component. The housing includes a protective layer on at least a portion of an inner wall.

Description

Technical Field

[0001] The present disclosure relates to wavelength converting elements containing phosphor particles. Background Art

[0002] Generally, fluorescent light sources adopt a method in which a fluorescent body is fixed to a wheel and the wheel is rotated to dissipate heat generated by laser radiation. In addition, for example, Patent Document 1 discloses a fluorescent body wheel that improves the cooling efficiency of the fluorescent body by enclosing a coolant together with the fluorescent body in a sealed housing provided on a rotating substrate.

[0003] Prior art literature

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-27685 Summary of the invention

[0006] Incidentally, a wavelength conversion element including a phosphor as a light source requires improved output power and reliability.

[0007] It is desirable to provide a wavelength conversion element that can improve output power and reliability.

[0008] According to an embodiment of the present disclosure, a first wavelength conversion element includes: a phosphor layer, a coolant, a coolant delivery component, and a shell. The phosphor layer contains a plurality of phosphor particles. The phosphor layer has voids therein. The coolant cools the phosphor layer. The coolant delivery component is arranged to contact the phosphor layer. The coolant delivery component circulates the coolant. The shell encapsulates the phosphor layer, the coolant, and the coolant delivery component. A protective layer is provided on at least a portion of the inner wall of the shell.

[0009] The first wavelength conversion element according to an embodiment of the present disclosure is provided with a protective layer on at least the portion of the inner wall of the housing enclosing the phosphor layer, the coolant and the coolant delivery member. This prevents contact between the coolant and the housing.

[0010] The second wavelength conversion element according to the embodiment of the present disclosure includes: a phosphor layer, a coolant, a coolant delivery component and a shell. The phosphor layer includes phosphor particles. The phosphor layer has a porous structure. The average pore size of the porous structure varies from one surface to the light-emitting portion on the other surface. The coolant cools the phosphor layer. The coolant delivery component is arranged to contact the phosphor layer. The coolant delivery component circulates the coolant. The shell encapsulates the phosphor layer, the coolant and the coolant delivery component.

[0011] The average pore size of the voids distributed in the phosphor layer having a porous structure of the second wavelength conversion element according to an embodiment of the present disclosure varies from the one surface to the light-emitting portion on the other surface. This improves cooling performance and reduces the entry of foreign matter into the light-emitting portion and the area near the light-emitting portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 : is a cross-sectional schematic diagram showing a configuration example of a wavelength conversion element according to the first embodiment of the present disclosure.

[0013] Figure 2 yes Figure 1 A schematic plan view of a wavelength conversion element is shown.

[0014] Figure 3 : is a cross-sectional schematic diagram showing another configuration example of the wavelength conversion element according to the first embodiment of the present disclosure.

[0015] Figure 4 is a flow chart of steps for manufacturing a phosphor layer.

[0016] Figure 5 It is an enlarged schematic diagram of a main part of a wavelength conversion element used as a reference example.

[0017] Figure 6 : is a cross-sectional schematic diagram showing a configuration example of a wavelength conversion element according to Modification 1 of the present disclosure.

[0018] Figure 7 yes Figure 6 A schematic plan view of the coolant delivery components is shown.

[0019] Figure 8 : is a cross-sectional schematic diagram showing another configuration example of the wavelength conversion element according to Modification 1 of the present disclosure.

[0020] Fig. 9 yes Figure 8 A schematic plan view of the coolant delivery components is shown.

[0021] Fig.10 : is a cross-sectional schematic diagram showing a configuration example of a wavelength conversion element according to Modification 2 of the present disclosure.

[0022] Fig.11 : is a cross-sectional schematic diagram showing a configuration example of a wavelength conversion element according to Modification 3 of the present disclosure.

[0023] Fig.12 yes Fig.11 A schematic plan view of a wavelength conversion element is shown.

[0024] Fig.13: is a cross-sectional schematic diagram showing a configuration example of a wavelength conversion element according to Modification 4 of the present disclosure.

[0025] Fig.14 : is a cross-sectional schematic diagram showing a configuration example of a wavelength conversion element according to Modification 5 of the present disclosure.

[0026] Fig.15 : is a cross-sectional schematic diagram showing another configuration example of the wavelength conversion element according to Modification 5 of the present disclosure.

[0027] Fig.16 : is a cross-sectional schematic diagram showing another configuration example of the wavelength conversion element according to Modification 5 of the present disclosure.

[0028] Fig.17 : is a cross-sectional schematic diagram showing another configuration example of the wavelength conversion element according to Modification 5 of the present disclosure.

[0029] Fig.18 : is a cross-sectional schematic diagram showing a configuration example of a wavelength conversion element according to Modification 6 of the present disclosure.

[0030] Fig.19 yes Fig.18 An enlarged cross-sectional schematic diagram of the main parts of the wavelength conversion element shown.

[0031] Fig. 20 : is a cross-sectional schematic diagram showing another configuration example of the wavelength conversion element according to Modification 7 of the present disclosure.

[0032] Fig.21 is a schematic cross-sectional view showing a configuration example of a wavelength conversion element according to a second embodiment of the present disclosure.

[0033] Fig. 22 yes Fig.21 A schematic plan view of a wavelength conversion element is shown.

[0034] Fig.23 It is shown Fig.21 An enlarged schematic diagram of a configuration example of a main part of a wavelength conversion element is shown.

[0035] Fig.24 It is shown Fig.21 An enlarged schematic diagram of another configuration example of the main parts of the wavelength conversion element shown.

[0036] Fig.25 Schematic diagram showing flow path resistance relative to the average particle size of phosphor particles.

[0037] Fig.26 It is a schematic cross-sectional view of a wavelength conversion element according to Modification 7 of the present disclosure.

[0038] Fig. 27 It is a schematic cross-sectional view of a wavelength conversion element according to Modification 8 of the present disclosure.

[0039] Fig.28 It is a schematic cross-sectional view of a wavelength conversion element according to variation 9 of the present disclosure.

[0040] Fig.29 It is a schematic cross-sectional view of a wavelength conversion element according to Modification 10 of the present disclosure.

[0041] Fig.30 It is a schematic cross-sectional view of a wavelength conversion element according to Modification 11 of the present disclosure.

[0042] Fig.31 It is a schematic cross-sectional view of a wavelength conversion element according to Modification 12 of the present disclosure.

[0043] Fig.32 It is a schematic cross-sectional view of a wavelength conversion element according to Modification 13 of the present disclosure.

[0044] Fig.33 It is shown that Figure 1 An overview diagram of an example of the configuration of a light source module including a wavelength conversion element shown.

[0045] Fig.34 It is shown that Figure 1 Schematic diagram of another configuration example of a light source module including a wavelength conversion element shown.

[0046] Fig.35 It is shown that Figure 1 Schematic diagram of another configuration example of a light source module including a wavelength conversion element shown.

[0047] Fig.36 It is shown that Figure 1 Schematic diagram of another configuration example of a light source module including a wavelength conversion element shown.

[0048] Fig.37 It is shown that Fig.33 An overview diagram of a configuration example of a projector of a light source module or the like shown.

[0049] Fig.38 It is shown that Fig.33 FIG. 1 is an overview diagram of another configuration example of a projector including a light source module or the like. DETAILED DESCRIPTION

[0050] The following describes the embodiments of the present disclosure in detail with reference to the accompanying drawings. The following description is a specific example of the present disclosure, but the present disclosure is not limited to the following modes. In addition, the present disclosure is not limited to the arrangement, size, size ratio and the like of the components shown in the various figures. It should be noted that the description is carried out in the following order.

[0051] 1. First Embodiment (Example in which a protective layer is provided on an inner wall of a receiving portion included in a housing)

[0052] 1-1. Structure of wavelength conversion element

[0053] 1-2. Actions and effects

[0054] 2. Modifications

[0055] 2-1. Modification 1 (Example in which a coolant transport member having a flow path is used)

[0056] 2-2. Modification 2 (Example of a Transmissive Wavelength Converter)

[0057] 2-3. Modification 3 (Example of a reflective wavelength conversion element rotatable about a rotation axis)

[0058] 2-4. Modification 4 (Example of a transmissive wavelength conversion element rotatable about a rotation axis)

[0059] 2-5. Modification 5 (Example in which a protective layer is further provided on the inner surface of the cover glass)

[0060] 2-6. Modification 6 (Example in which the coolant transport member is formed by using a particle or fiber structure)

[0061] 3 Second Embodiment (Example in which a phosphor layer having an average pore size distribution is used)

[0062] 3-1. Structure of wavelength conversion element

[0063] 3-2. Actions and effects

[0064] 4. Modifications

[0065] 4-1. Modification 7 (Another example of average pore size distribution)

[0066] 4-2. Modification 8 (Another example of average pore size distribution)

[0067] 4-3. Modification 9 (Example in which the side wall of the phosphor layer is inclined)

[0068] 4-4. Modification 10 (Example in which a porous layer is provided between the phosphor layer and the cooling and transporting member)

[0069] 4-5. Modification 11 (Example of a Transmissive Wavelength Converter)

[0070] 4-6. Modification 12 (Example in which the opening directly below the light-emitting portion is filled with glass)

[0071] 4-7. Modification 13 (Example of Combination of First Embodiment and Second Embodiment)

[0072] 5. Application examples (light source module and projector examples)

[0073] <1. First Embodiment>

[0074] Figure 1 An example of a cross-sectional configuration of a wavelength conversion element (wavelength conversion element 1A) according to the first embodiment of the present disclosure is schematically shown. Figure 2 Schematically shows Figure 1 The planar structure of the wavelength conversion element 1A is shown. Figure 1 Shown along Figure 2 The wavelength conversion element 1A is included in a projection display device (projector 1000) (see FIG. Figures 32 to 38 ). The wavelength conversion element 1A has a configuration in which a phosphor layer 11 and a coolant delivery member 12 are enclosed in a housing 20 together with a coolant 13. The phosphor layer 11 and the coolant delivery member 12 are stacked together. The phosphor layer 11 is directly cooled by the latent heat of evaporation of the coolant 13.

[0075] (1-1. Structure of wavelength conversion element)

[0076] As described above, the wavelength conversion element 1A has a so-called two-phase cooling structure, in which the phosphor layer 11 and the coolant delivery component 12 are enclosed in the shell 20 together with the coolant 13. The phosphor layer 11 is directly cooled by the latent heat of evaporation of the coolant 13. The shell 20 includes, for example, a housing 21 and a cover glass 22. The cover glass 22 has light transmittance and is combined with the housing 21 to seal the internal space of the housing 21. A heat dissipation component 23 is provided on the rear surface of the housing 21. The wavelength conversion element 1A according to the present embodiment also includes a protective layer 24. The protective layer 24 is provided on at least a portion of the inner wall of the shell 20. The inner wall defines an internal space in which the phosphor layer 11, the coolant delivery component 12 and the coolant 13 are enclosed.

[0077] The phosphor layer 11 contains a plurality of phosphor particles. The phosphor layer 11 is preferably formed into, for example, a continuous foam type porous layer. However, as described in detail below, it is preferred that the size of these pores (average pore diameter) be smaller than the average pore diameter of the coolant transport member 12, which is also formed into a continuous foam type porous layer. For example, an average pore diameter of 30 μm or less is preferred. The phosphor layer 11 is preferably formed into, for example, a plate-like or cylindrical shape. The phosphor layer 11 includes, for example, a so-called ceramic phosphor or an adhesive type porous phosphor.

[0078] Each of the phosphor particles is a granular phosphor that absorbs the excitation light EL radiated from the light source section 110 described below to emit fluorescence FL. For example, as the phosphor particles, a fluorescent material that is excited by a blue laser having a wavelength in a blue wavelength range (e.g., 400 nm to 470 nm) to emit yellow fluorescence (light in a wavelength range between a red wavelength range and a green wavelength range) is used. Examples of such fluorescent substances include YAG (yttrium / aluminum / garnet)-based materials. For example, the phosphor particles have an average particle size of 10 μm or more and 100 μm or less.

[0079] It is preferable that the phosphor layer 11 has a smaller diameter, for example, smaller than the diameter of the coolant delivery member 12, and has a space (space 12S) between the side surface of the phosphor layer 11 and the side wall of the housing 20 (accommodation portion 21). This allows the coolant 13 to circulate efficiently in the cooling cycle of the wavelength conversion element 1A described below.

[0080] Furthermore, it is preferable that at least a portion of the surface 11S1 of the phosphor layer 11 disposed in the housing 21 facing the cover glass 22, which corresponds to the light-emitting portion, is in contact with or bonded to the cover glass 22. The light-emitting portion converts the excitation light EL into the fluorescence FL. This makes it possible to prevent the droplets from adhering to the surface 22S of the cover glass 22 directly opposite to the light-emitting portion and prevent the excitation light EL and the fluorescence FL from being scattered by the droplets. It should be noted that Figure 1 In the example shown, the phosphor layer 11 is stacked on the coolant conveying member 12, but it is not limited thereto. Figure 3 As shown, for example, an opening 12H may be provided in the coolant delivery member 12, and the phosphor layer 11 may be inserted into the opening 12H. The opening 12H has a diameter substantially the same as the outer diameter of the phosphor layer 11. In this case, like the surface 11S1, a surface 11S2 of the phosphor layer 11 facing the bottom surface of the accommodation portion 21 may be in contact or engaged with the accommodation portion 21 (specifically, the protective layer 24).

[0081] The coolant conveying member 12 is used to carry the coolant 13 to the phosphor layer 11. Preferably, the coolant conveying member 12 is formed as a continuous foam type porous layer like the phosphor layer 11. Preferably, the average pore size of the coolant conveying member 12 is larger than that of the phosphor layer 11.

[0082] The wavelength conversion element 1A according to the present embodiment is a so-called reflective wavelength conversion element, which extracts the fluorescence FL by, for example, reflecting the fluorescence FL in the same direction as the input direction of the excitation light EL. The fluorescence FL is emitted from the phosphor layer 11 irradiated by the excitation light EL. Therefore, it is preferable that the coolant delivery member 12 further has light reflectivity. For example, it is preferable to use an inorganic material such as a metal material or a ceramic material. Examples of materials included in the coolant delivery member 12 include single metals such as aluminum (Al), copper (Cu), molybdenum (Mo), tungsten (W), cobalt (Co), chromium (Cr), platinum (Pt), tantalum (Ta), lithium (Li), zirconium (Zr), ruthenium (Ru), rhodium (Rh) or palladium (Pd) or alloys including one or more of the above metals. The coolant delivery member 12 includes a sintered ceramic compact, a sintered metal or a porous metal, and the porous metal includes, for example, the above materials.

[0083] For example, Figure 1 As shown, the coolant 13 circulates between the phosphor layer 11 and the coolant conveying member 12 to cool the phosphor particles heated by the irradiation of the excitation light EL. For example, it is preferable to use a liquid having a large latent heat for the coolant 13. In addition, the coolant 13 circulates through the gaps formed in the phosphor layer 11 and the coolant conveying member 12. Therefore, it is preferable that the coolant 13 has a low viscosity. Specific examples of the coolant 13 include water, acetone, methanol, naphthalene, benzene, and the like.

[0084] One surface of the housing 20 includes a material having light transmittance. A sealed space (internal space) may be formed in the housing 20. As described above, the housing 20 includes a housing portion 21 and a cover glass 22, the cover glass 22 is combined with the housing portion 21 to form a sealed space and the cover glass 22 corresponds to one surface described above. The cover glass 22 corresponds to a specific example of a "sealing portion" according to the present disclosure. The housing portion 21 accommodates the phosphor layer 11, the coolant delivery member 12, and the coolant 13. The phosphor layer 11 and the coolant delivery member 12 are arranged so that the phosphor layer 11 faces the cover glass 22 side (for example, at Figure 1As a material included in the housing 20, for example, aluminum, copper, stainless steel, low carbon steel, alloy materials thereof, etc. are used for the accommodating portion 21. In addition to the glass substrate, for example, soda glass, quartz, sapphire glass, crystal, etc. are used for the cover glass 22. In addition, in the case where the light source portion 110 outputs laser light with low output power, resins such as polyethylene terephthalate (PET), silicone resin, polycarbonate, and acrylic are used.

[0085] The surface of the housing 20 opposite to the one surface or the rear surface of the accommodating portion 21 is provided with a heat dissipation member 23. The heat dissipation member 23 is used to cool the accommodating portion 21. This causes the vapor of the coolant 13 to condense on the inner surface side of the accommodating portion 21, thereby causing a phase change to become liquid, and the liquid is transported to the phosphor layer 11 by the coolant transport member 12. For example, a plurality of heat dissipation fins may be used as Figure 1 The heat sink 23 shown is, but not limited to, a Pall tape element or a water cooling element may be used as the heat sink 23 .

[0086] The protective layer 24 is formed on at least a portion of the inner wall defining the inner space of the housing 20. The protective layer 24 is used to prevent the housing 20 from contacting the coolant 13. For example, it is preferable to form the protective layer 24 on the entire inner wall of the accommodation portion 21. This prevents foreign matter from being dissolved in the coolant 13 from the accommodation portion 21 (e.g., elution of metal ions from the metal included in the accommodation portion 21) and prevents the metal included in the accommodation portion 21 from being corroded.

[0087] It is preferred to use a coolant 13 of a material with high affinity for the protective layer 24. For example, in the case of using water as the coolant 13, the material of the protective layer 24 includes an oxide with high hydrophilicity, such as silicon oxide (SiO2), aluminum oxide (Al2O3) and titanium oxide (TiO2). In addition, a metal material such as gold (Au), silver (Ag) or stainless steel having a standard electrode potential greater than 0.35V and not prone to rust may be used. In this case, it is preferred to perform plasma treatment on the surface of the metal film and provide hydroxyl groups on the surface. This increases the affinity with the coolant 13 (e.g., water). Alternatively, the above-mentioned oxide film may be formed on the surface of the above-mentioned metal film. In addition to the above-mentioned materials, examples of metal materials also include zinc (Zn), nickel (Ni) and chromium (Cr) or alloys including these materials. The protective layer 24 may be a single-layer film or a stacked film. In the case where the protective layer 24 is formed as a stacked film, it is preferred to form the above-mentioned oxide film on the outermost layer, for example. The protective layer 24 may be formed, for example, by vapor deposition, film formation by a sputtering device, coating such as spin coating, plating, or mechanical bonding.

[0088] It should be noted that providing a tiny (e.g., several μm to several mm) concavo-convex structure on the surface of the protective layer 24 can also increase the affinity with the coolant 13. Providing a concavo-convex structure on the surface of the protective layer 24 helps the coolant 13 to enter the surface of the protective layer 24 through capillary force like the above-mentioned coolant delivery member 12, and increase the affinity (wettability). In addition, in addition to the function of protecting the surface of the accommodating portion 21, the protective layer 24 can be provided with an optical reflection function, an optical anti-reflection function, a color separation function, a polarization separation function, an optical phase adjustment function, a high thermal conductivity function, etc.

[0089] As described above, the wavelength conversion element 1A according to the present embodiment has a two-phase cooling structure in which the stacked phosphor layer 11 and the coolant transport member 12 are enclosed in the housing 20 together with the coolant 13. The housing 20 has a sealed internal space. The phosphor layer is directly cooled by the latent heat of vaporization of the coolant 13. In order to circulate the coolant 13 from the coolant transport member 12 to the phosphor layer 11, it is desirable to make the capillary force generated in the phosphor layer greater than the capillary force generated in the coolant transport member 12. The capillary force is expressed by the following formula.

[0090] (Formula 1) P = 2Tcosθ / ρgr…(1)

[0091] (P represents capillary force, T represents surface tension, θ represents contact angle, ρ represents liquid density, g represents gravitational acceleration, and r represents capillary radius)

[0092] The equivalent capillary radius of the coolant transport member 12 is proportional to the average pore size. In order to make the capillary force of the phosphor layer 11 larger than the capillary force of the coolant transport member 12, it is known from the above formula (1) that the average pore size of the coolant transport member 12 is preferably larger than the average pore size of the phosphor layer 11. In addition, as indicated by the formula (1), the one of the phosphor layer 11 and the coolant transport member 12 having a smaller contact angle has a larger capillary force. Therefore, it is desirable that the materials included in the phosphor layer 11 and the coolant transport member 12 both have wettability.

[0093] It should be noted that in the case where the wavelength conversion element 1A according to the present embodiment is vertically erected for use, the capillary force of the coolant conveying member 12 must overcome gravity and suck the coolant 13 upward to the irradiation position (light-emitting portion) of the excitation light EL. Therefore, in the case where R0 represents the distance from the light-emitting portion to the outermost periphery (the inner side surface of the accommodating portion 21), it is desirable that the capillary force P of the coolant conveying member 12 satisfies P ≥ the head difference R0 (mmH2O). However, this does not apply to the case where the wavelength conversion element is rotated for use, as in the wavelength conversion element 1D described below.

[0094] In the case where both the phosphor layer 11 and the coolant transport member 12 are formed by using a sintered compact, controlling predetermined parameters in the manufacturing steps of each of the sintered compacts provides a desired average pore diameter. A sintered phosphor is described below as an example. Figure 4 Flow chart of the steps of manufacturing a sintered phosphor. First, the phosphor is classified to control the particle size of the phosphor particles (step S101). Then the phosphor particles and the binder are mixed together (step S102). Next, the pressing pressure is controlled to perform uniaxial pressing (step S103). Then, degreasing is performed (step S104) and then sintering is performed (step S105). As described above, a phosphor layer 11 including a sintered phosphor is formed. The average pore size of the sintered phosphor can be adjusted to a desired value by classifying the phosphor in step S101, controlling the pressing pressure for uniaxial pressing in step S103, and controlling the sintering temperature in step S105.

[0095] The cooling cycle of the wavelength conversion element 1A according to the present embodiment is described. First, in the case where the phosphor layer 11 is irradiated with the excitation light EL, the phosphor particles generate heat. The coolant 13 is evaporated by the heat and takes away the latent heat at the same time. Figure 1 As shown, in the case where the middle part of the phosphor layer 11 is irradiated with the excitation light EL, the evaporated coolant 13 moves to the space 12S on the outer peripheral side in the form of vapor. The vapor that has moved to the space 12S dissipates latent heat through the inner wall of the accommodating portion 21 and liquefies again. The liquefied coolant 13 is transported to the phosphor layer 11 by the capillary force of the coolant transport member 12, and moves to the heat generating portion of the phosphor layer 11 by the capillary force of the phosphor layer 11. By repeating this process, the heat generated by the radiation of the excitation light EL is discharged to the coolant transport member 12.

[0096] (1-2. Actions and Effects)

[0097] In recent years, laser excited phosphors have been used as light sources in projection display devices (projectors). Laser excited phosphor light sources have problems in increasing the cooling efficiency of the phosphor. Two-phase flow cooling technology (phase change cooling technology) using latent heat has attracted attention. This two-phase flow cooling technology allows the coolant to directly cool the phosphor or the luminescent particles of the luminescent area.

[0098] However, in the case where a metal material is used for a sealed housing enclosing a phosphor and a coolant, metal ions are eluted into the coolant, or the metal included in the sealed housing is corroded. Figure 5As shown, the metal ions eluted into the coolant move to the light emitting portion X of the phosphor layer 1100 together with the coolant 1300. The coolant 1300 vaporizes and evaporates, while taking away the heat generated in the case of emitting fluorescence. However, in this case, the metal ions included in the coolant 1300 remain on the surface of the phosphor particles in the light emitting portion X and the area near the light emitting portion X. This in turn causes the deposit M of the metal ions to adhere to the surface of the phosphor particles in the light emitting portion X and the area near the light emitting portion X. The deposit M absorbs and scatters the excitation light or fluorescence. As a result, the laser excitation phosphor light source has a smaller light output power.

[0099] Possible countermeasures against metal deposition include suppressing the change in properties by including a metal with a non-conductive coating formed on the surface in a sealed housing or oxidizing the surface of the housing in advance. However, in an environment where the coolant is in continuous contact for a long period of time and the temperature of the coolant varies, it is difficult to prevent the elution or corrosion of metal ions without substantially affecting the optical output power.

[0100] In contrast, in the present embodiment, a protective layer 24 is provided on the inner wall of the accommodation portion 21 defining the inner space of the housing 20, thereby preventing the coolant 13 from contacting the accommodation portion 21. This prevents metal ions from eluting into the coolant 13 and prevents the metal included in the accommodation portion 21 from being corroded.

[0101] As described above, the wavelength conversion element 1A according to the present embodiment is provided with the protective layer 24 on the inner wall of the housing portion 21 defining the internal space. This makes it possible to prevent the metal ions from eluting from the housing portion 21 into the coolant 13, prevent the housing portion 21 from being corroded, and prevent the deposits of the metal ions from adhering to the light emitting region, in particular, of the phosphor layer 11. Therefore, a wavelength conversion element having high output power and high reliability can be realized.

[0102] In addition, the wavelength conversion element 1A according to the present embodiment uses two-phase cooling. This keeps the phosphor layer 11 at a constant temperature. This makes it possible to stabilize the light source output power in the light source module including the wavelength conversion element 1A, and allows the projector including the light source module to have higher image quality.

[0103] Furthermore, a non-rotating wavelength conversion element having efficient cooling performance and allowing stable use can be realized in this embodiment. This makes it possible to miniaturize the light source module and the projector. Furthermore, compared with the use of a rotating wavelength conversion element, there is less concern about image quality degradation caused by rotating flash. Therefore, the light source output power can be further stabilized. In addition, the image quality of the projector including this light source can be further improved.

[0104] Next, the second embodiment, modifications 1 to 13, and application examples are described. Hereinafter, components similar to those of the first embodiment described above are assigned the same reference numerals, and description of the similar components is appropriately omitted.

[0105] <2. Modifications>

[0106] (2-1. Modification 1)

[0107] Figure 6 An example of a cross-sectional configuration of a wavelength conversion element (wavelength conversion element 1B) according to Modification 1 of the present disclosure is schematically shown. Figure 7 Schematically shows Figure 6 An example of a planar configuration of the coolant delivery member 32 is shown. It should be noted that Figure 6 The cross section of the coolant delivery member 32 is along Figure 7 II-II shown. As in the first embodiment described above, the wavelength conversion element 1B is included in a light source module (light source module 100) of a projection display device (projector 1000). The wavelength conversion element 1B according to this modification encloses the stacked phosphor layer 11 and the coolant delivery component 32 together with the coolant 13 in the housing 20, and is different from the first embodiment described above in that the coolant delivery component 32 includes a metal plate having a micro flow path 32X formed on a contact surface with the phosphor layer 11.

[0108] The coolant transport member 32 is used to carry the coolant 13 to the phosphor layer 11. As described above, the coolant transport member 32 has a micro flow path 32X formed on the contact surface with the phosphor layer 11. Grooves are formed on the surface S1 (contact surface with the phosphor layer 11) of the coolant transport member 32 by micromachining to serve as the flow path 32X. These grooves extend radially from the middle of the coolant transport member 32 to the outer periphery, for example, Figure 7 As shown. Each of these flow paths 32X is formed to have a width and depth of, for example, tens of μm to hundreds of μm. This generates capillary force. It should be noted that, as in the above-described first embodiment, the flow paths 32X are formed so that the capillary force of the coolant transport member 32 is smaller than the capillary force of the phosphor layer 11. In addition, Figure 7 An example is shown in which the flow path 32X radially extends from the middle of the coolant delivery member 32 to the outer periphery of the coolant delivery member 32, but is not limited thereto. For example, the flow path 32X may be formed to have a lattice shape or a spiral shape.

[0109] It is preferable to use a material having high wettability and hydrophilicity for the metal plate included in the coolant delivery member 32. Furthermore, in consideration of the use as a light reflecting layer, for example, it is preferable to use an aluminum (Al) substrate. In addition, a substrate including an inorganic material including the material included in the above-mentioned coolant delivery member 12, such as a copper (Cu) substrate, may be used, but in this case it is preferable to form a high reflection film on the surface.

[0110] in addition, Figure 6 An example is shown in which the phosphor layer 11 is stacked on the coolant transporting member 12 in the accommodation portion 21 , but is not limited thereto. Figure 8 An example of a cross-sectional configuration of a wavelength conversion element 1B according to Modification 1 of the present disclosure is schematically shown. Fig. 9 Schematically shows Figure 8 Another example of a planar configuration of the coolant delivery member 32 is shown. It should be noted that Figure 8 The cross section of the coolant delivery member 32 is along Fig. 9 For example, as described above Figure 3 The wavelength conversion element 1A shown, the wavelength conversion element 1B according to the present modification may be provided with an opening 32H on the coolant conveying member 32, and the phosphor layer 11 may be inserted into the opening 32H. The opening 32H has substantially the same diameter as the outer diameter of the phosphor layer 11.

[0111] As described above, in the present modification, using a metal plate having flow path 32X of a predetermined size on the contact surface with phosphor layer 11 as coolant transport member 32 also makes it possible to obtain effects similar to those of the above-described first embodiment.

[0112] It should be noted that the flow path 32X may also be formed directly on the housing portion 21. In this case, the coolant conveying member 32 may be omitted. This makes it possible to reduce the components included in the wavelength conversion element 1B and to miniaturize (thinnen) the wavelength conversion element 1B.

[0113] (2-2. Modification 2)

[0114] Fig.10 The cross-sectional structure of the wavelength conversion element (wavelength conversion element 1C) according to the modification example 2 of the present disclosure is schematically shown. As in the first embodiment described above, the wavelength conversion element 1C is included in the light source module (light source module 100) of the projection display device (projector 1000). The wavelength conversion element 1C according to this modification example is a so-called transmissive wavelength conversion element, in which the fluorescent light FL emitted from the fluorescent layer 11 passes through the fluorescent layer 11 and is extracted from the surface opposite to the surface irradiated with the excitation light EL.

[0115] In this modification, the coolant conveying member 12 is provided with an opening 12H at a position corresponding to the light emitting portion of the phosphor layer 11 (the irradiation position of the excitation light EL). Figure 3 In the wavelength conversion element 1A shown, the phosphor layer 11 is inserted into the opening 12H. The surface of the input excitation light EL of the phosphor layer 11 (for example, the surface 11S2) and the surface of the output fluorescence FL of the phosphor layer 11 (for example, the surface 11S1) are in contact or engagement with the accommodating portion 21 and the cover glass 22, respectively. The housing 40 includes a back cover 41A, a side wall 41B and a cover glass 42. The back cover 41A and the cover glass 42 each include a light-transmitting material. The side wall 41B can be formed by using the above-mentioned materials mentioned for the accommodating portion 21, or can be formed by using a material similar to that of the cover glass 42 and the back cover 41A. This, for example, converts the excitation light EL radiated from the back cover 41A side into fluorescence FL in the phosphor layer 11, and extracts the fluorescence FL from the cover glass 42 side. The heat dissipation component 43 is provided in an area that does not block the radiation of the excitation light EL, for example, as Fig.10 shown.

[0116] It is preferred that the protective layer 44 is formed at least on the inner side of the side wall 41B of the accommodating portion 41 defining the inner space of the housing 40. The protective layer 44 may also be further formed on the surface 41S of the rear cover constituting the bottom surface of the inner space, such as Fig.10 As shown. In this case, it is preferable to form the protective layer 44 except for the region adjacent to the fluorescent layer 11, for example, so as not to block the input of the excitation light EL. However, this is not the case when the protective layer 44 is transmissive to the excitation light EL and the fluorescent light FL. The protective layer 44 may be formed on the entire surface 41S of the rear cover 41A.

[0117] As described above, in the present modification, the rear cover 41A having light transmittance is used for the bottom surface of the housing portion 41. This makes it possible to configure a transmissive wavelength conversion element 1C having effects similar to those of the above-described first embodiment.

[0118] (2-3. Modification 3)

[0119] Fig.11 An example of a cross-sectional configuration of a wavelength conversion element (wavelength conversion element 1D) according to Modification 3 of the present disclosure is schematically shown. Fig.12 Schematically shows Fig.11 The planar structure of the wavelength conversion element 1D is shown. Fig.11 Shown along Fig.12The cross-sectional structure taken along the line IV-IV is shown. As in the first embodiment described above or in a similar manner, the wavelength conversion element 1D is included in a light source module (light source module 100) of a projection display device (projector 1000). The wavelength conversion element 1D according to this variation is a so-called reflective fluorescent wheel that can rotate around a rotation axis (e.g., axis J51).

[0120] In this modification, the phosphor layer 11 is arranged along a circular coolant delivery member 12 (for example, Fig.12 In other words, the phosphor layer 61 is formed to have, for example, a ring shape.

[0121] As in the first embodiment described above, the protective layer 24 is formed on the inner wall of the housing portion 21 defining the inner space of the housing 20. An opening 12H is provided on the coolant delivery member 12, and the opening 12H has substantially the same shape as the annular-shaped phosphor layer 11. The phosphor layer 11 is inserted into the opening 12H. A surface 11S1 of the phosphor layer 11 facing the cover glass 22 and a surface 11S2 facing the bottom surface of the housing portion 21 are in contact or engagement with the cover glass 22 and the housing portion 21, respectively.

[0122] The housing 20 according to the present modification is a wheel component. For example, a motor 55 is attached to the housing 20. The motor 55 is used to rotate and drive the wavelength conversion element 1D at a predetermined rotation speed. The motor 55 drives the wavelength conversion element 1D to rotate the phosphor layer 61 in a plane orthogonal to the radiation direction of the excitation light EL emitted from the light source section 110. This temporarily changes (moves) the position where the excitation light EL irradiates the wavelength conversion element 1D in a plane orthogonal to the radiation direction of the excitation light at a speed corresponding to the rotation speed.

[0123] (2-4. Modification 4)

[0124] Fig.13 An example of a cross-sectional configuration of a wavelength conversion element (wavelength conversion element 1E) according to a modification example 4 of the present disclosure is schematically shown. As in the first embodiment described above or in a similar manner, the wavelength conversion element 1E is included in a light source module (light source module 100) of a projection display device (projector 1000). The wavelength conversion element 1E according to this modification example is a so-called transmissive fluorescent wheel rotatable around a rotation axis (e.g., axis J51).

[0125] In this modification, as in the above-mentioned modification 2, the housing 40 includes a rear cover 41A, a side wall 41B and a cover glass 42. The rear cover 41A and the cover glass 42 each include a light-transmitting material. In addition, as in the above-mentioned modification 2, the protective layer 44 is also formed, for example, on the inner side of the side wall 41B that defines the internal space of the accommodating portion 41. In addition, the protective layer 44 is formed on the surface 41S of the rear cover 41A constituting the bottom surface of the internal space, except for, for example, the area adjacent to the phosphor layer 11. However, as described above, this is not the case when the protective layer 44 is transmissive to the excitation light EL and the fluorescent light FL. The protective layer 44 may be formed on the entire surface 41S of the rear cover 41A.

[0126] As described above, the present technology can also be applied to a rotating wavelength conversion element. It is possible to prevent the deposit of metal ions from adhering to the light-emitting portion of the phosphor layer 11 and the area near the light-emitting portion, and to improve the output power and reliability. In addition, in the rotating wavelength conversion element, in addition to the capillary force mentioned above, the centrifugal force also promotes the circulation of the coolant 13. Therefore, the above-mentioned rotating wavelength conversion elements 1D and 1E can obtain higher cooling performance than non-rotating wavelength conversion elements (such as the above-mentioned wavelength conversion elements 1A to 1C).

[0127] (2-5. Modification 5)

[0128] Fig.14 Another example of the cross-sectional configuration of the wavelength conversion element 1A used as a modified example of the above-mentioned first embodiment is schematically shown. This example has been described in the above-mentioned first embodiment, in which the protective layer 24 is provided on the inner wall of the housing 21, but is not limited thereto. This modified example is different from the above-mentioned first embodiment in that, in addition to the inner wall of the housing 21, the protective layer 54 is also formed on the surface 22S1 of the cover glass 22. The surface 22S1 of the cover glass 22 defines the internal space together with the housing 21.

[0129] As described above, the protective layer 54 is provided on the entire inner wall of the accommodating portion 21 and the cover glass 22 which define the internal space of the housing 20. However, it is preferable to form the protective layer 54 on the surface 22S1 of the cover glass 22 except for the area adjacent to the phosphor layer 11, for example, so as not to block the input of the excitation light EL and not to block the output of the fluorescence FL. However, this is not the case when the protective layer 44 is transmissive to the excitation light EL and the fluorescence FL. The protective layer 44 may be formed on the entire surface 41S of the back cover 41A. The protective layer 54 may be formed by using, for example, the materials mentioned in the above-mentioned first embodiment. However, for the protective layer 54 formed on the surface 22S1 of the cover glass 22, it is preferable to use a light-shielding metal material among the above-mentioned materials. This obtains an effect that makes it possible to suppress stray light in addition to the effect according to the above-mentioned first embodiment.

[0130] It should be noted that the configuration according to the present modification example can also be applied to the wavelength conversion elements 1B to 1E described in the above-mentioned modifications 1 to 4. Figures 15 to 17 Schematically showing other examples of cross-sectional configurations of wavelength conversion elements 1B to 1E according to a combination of the configuration according to this modification and the above-described corresponding modifications 1 to 4. As described above, providing the light-shielding protective layer 54 to the surface 22S1 of the cover glass 22 (or the surface 42S1 of the cover glass 42) enables, in addition to the effects according to the above-described modifications 1 to 4, an effect of suppressing stray light can be obtained.

[0131] (2-6. Modification 6)

[0132] This embodiment has been described in the above-mentioned first embodiment or the like, in which the coolant transport member (eg, coolant transport member 12) includes a sintered ceramic compact, a sintered metal, or a porous metal, but the coolant transport member may include, for example, the following materials.

[0133] Fig.18 An example of a cross-sectional configuration of a wavelength conversion element (wavelength conversion element 1F) according to Modification 6 of the present disclosure is schematically shown. Fig.19 yes Fig.18 1F is an enlarged view of the configuration of the coolant delivery component 52 shown. The wavelength conversion element 1F is a reflective wavelength conversion element. The coolant delivery component 52 includes a plurality of particles 52X, each of which has, for example, light reflectivity. Examples of each of the particles 52X having light reflectivity include barium sulfate (BaSO4), titanium oxide (TiO2), aluminum oxide (Al2O3), and the like. Preferably, the surfaces of the plurality of particles 52X included in the coolant delivery component 52 are covered with a protective layer 52Y similar to the protective layer 24 provided on, for example, the inner wall of the housing 20. This makes it possible to prevent metal ions from eluting from the plurality of particles 52X into the coolant 13 ( Fig.18 (not shown) and prevent the plurality of particles 52X from being corroded by the coolant 13.

[0134] In the wavelength conversion element 1F according to the present modification, in the coolant delivery member 52, a plurality of particles 52X are partially in contact with the wall surface of the internal space of the housing 20. A space 52S is provided in the middle of the housing 20. The coolant 13 circulates to the phosphor layer 11 through the gap in the coolant delivery member 52 provided along the inner wall of the housing 20. The coolant 13 evaporates in the phosphor layer 11 and the evaporated coolant 13 is discharged to the space 52S formed in the middle of the housing 20.

[0135] It should be noted that the wavelength conversion element 1F according to the present modification includes particles each having light transmittance in the coolant delivery member 52. This makes it possible to construct a transmissive wavelength conversion element. Examples of particles each having light transmittance include SiO2-based glass, aluminum oxide (Al2O3) particles. In the case where the coolant delivery member 52 includes particles each having light transmittance, some portions of the phosphor layer 11 or specifically the portions in contact with the surface 42S of the cover glass 42 and the surface 41S of the rear cover 41A may include the particles included in the coolant delivery member 52.

[0136] Furthermore, in addition to the case of the plurality of particles 52X, the coolant transporting member 52 may include, for example, a fiber structure 52F. Fig. 20 The cross-sectional configuration of a wavelength conversion element 1F including a coolant delivery component 52 is schematically shown, and the coolant delivery component 52 includes a fiber structure 52F. Examples of materials of the fiber structure 52F include metals such as aluminum (Al), copper (Cu) and stainless steel, resins, glass, ceramics, and the like. The fiber structure 52F may include one of the above materials or a combination of two or more of the above materials. It should be noted that in the case where a material in which metal ions may be eluted into the coolant 13 or may be corroded by the coolant 13 is used as the coolant delivery component 52, it is preferred to cover the surface of the material with a protective layer 54Y as described above. The same situation applies to the case where the coolant delivery component 32 is formed by using an aluminum (Al) substrate, a copper (Cu) substrate, etc., as in the wavelength conversion element 1B according to the above-mentioned modification example 1.

[0137] <3. Second Embodiment>

[0138] Fig.21 An example of a cross-sectional configuration of a wavelength conversion element (wavelength conversion element 1G) according to the second embodiment of the present disclosure is schematically shown. Fig. 22 Schematically shows Fig.21 The planar structure of the wavelength conversion element 1G is shown. Fig.21 Shown along Fig. 22 The wavelength conversion element 1G is included in a light source module (light source module 100) of a projection display device (projector 1000) described below, for example (see Figures 32 to 38 The wavelength conversion element 1G according to the present embodiment has a configuration in which the phosphor layer 61 and the coolant conveying member 12 are enclosed in the housing 20 together with the coolant 13. The phosphor layer 61 and the coolant conveying member 12 are stacked together. The phosphor layer 61 is directly cooled by the evaporation latent heat of the coolant 13.

[0139] (3-1. Structure of wavelength conversion element)

[0140] As described above, the wavelength conversion element 1G according to the present embodiment has a so-called two-phase cooling structure in which the phosphor layer 61 and the coolant delivery member 12 are enclosed in the housing 20 together with the coolant 13. The phosphor layer 61 is directly cooled by the latent heat of evaporation of the coolant 13. The housing 20 includes, for example, a housing 21 and a cover glass 22. The cover glass 22 has light transmittance and is combined with the housing 21 to seal the internal space of the housing 21. The heat dissipation member 23 is provided on the rear surface of the housing 21. In the present embodiment, the phosphor layer 61 is configured so that its average pore size is different between the surface 61S1 facing the cover glass 22 and the surface 61S2 facing the coolant delivery member 12.

[0141] The phosphor layer 61 includes a plurality of phosphor particles. The phosphor layer 61 is preferably formed as, for example, a continuous foam type porous layer. Although described in detail below, it is preferred that the size of these pores (average pore diameter) is smaller than the average pore diameter of the coolant transport member 12, which is also formed as a continuous foam type porous layer. For example, an average pore diameter of 30 μm or less is preferred. The phosphor layer 61 is preferably formed to have, for example, a plate-like or cylindrical shape. The phosphor layer 61 includes, for example, a so-called ceramic phosphor or an adhesive type porous phosphor.

[0142] Each phosphor particle is a granular phosphor that absorbs the excitation light EL radiated from the light source section 110 described below to emit fluorescence FL. For example, as the phosphor particles, a fluorescent material that is excited by a blue laser having a wavelength in a blue wavelength range (e.g., 400 nm to 470 nm) to emit yellow fluorescence (light in a wavelength range between a red wavelength range and a green wavelength range) is used. Examples of such fluorescent substances include YAG (yttrium / aluminum / garnet)-based materials. For example, the phosphor particles have an average particle size of 10 μm or more and 100 μm or less.

[0143] Preferably, the phosphor layer 61 has a smaller diameter, for example, smaller than the diameter of the coolant delivery member 12, and has a space (space 12S) between the side surface of the phosphor layer 61 and the side wall of the housing 20 (accommodation portion 21). This allows the coolant 13 to circulate efficiently in the cooling cycle of the wavelength conversion element 1G described below. In addition, it is preferred that a portion of the surface 61S1 of the phosphor layer 61 corresponding to at least the light-emitting portion is in contact with or engaged with the cover glass 22 in the accommodation portion 21. The surface 61S1 is arranged to face the cover glass 22. The light-emitting portion converts the excitation light EL into the fluorescence FL. This makes it possible to prevent droplets from adhering to the surface 22S of the cover glass 22 directly opposite to the light-emitting portion and prevent the excitation light EL and the fluorescence FL from being scattered by the droplets.

[0144] Furthermore, as described above, the phosphor layer 61 is configured such that its average pore size is different between the surface 61S1 facing the cover glass 22 and the surface 61S2 facing the coolant transport member 12. For example, the phosphor layer 61 has a porous structure in which the average pore size of the phosphor layer 61 changes from the surface 61S2 to the surface 62S1. The surface 61S2 corresponds to a specific example of “one surface” according to the present disclosure, and the surface 62S1 corresponds to a specific example of “another surface or other surface” according to the present disclosure.

[0145] Fig.23 and Fig.24 Each is an enlarged view of a cross-sectional configuration of the phosphor layer 61 and a region surrounding the phosphor layer 61. The phosphor layer 61 is a main portion of the wavelength conversion element 1F according to the present disclosure. Fig.23 The phosphor layer 61 shown has a stacked structure in which a first layer 61A and a second layer 61B are stacked in sequence starting from the coolant conveying part 12 side. The first layer 61A has a predetermined average pore size. The second layer 61B has a higher particle density than the first layer 61A. The second layer 61B includes a light source portion that converts the radiated excitation light EL into fluorescence FL. For example, it is preferred that the second layer 61B has a non-porous structure with no voids (holes) inside it. This makes it possible to prevent foreign matter from entering the light source portion. In addition, the first layer 61A does not contribute to light emission. The first layer 61A does not have to be formed using phosphor particles, as long as it can include a continuous foam-type porous layer.

[0146] exist Fig.24 In the phosphor layer 61 shown, the first layer 61A has a multilayer structure in which a plurality of layers (e.g., three layers 61A1, 61A2, and 61A3) having different average pore sizes are stacked. These layers 61A1, 61A2, and 61A3 are stacked so that the average pore size gradually decreases along the direction in which the coolant 13 flows. In other words, among these layers 61A1, 61A2, and 61A3, layer 61A1 has the largest average pore size, layer 61A2 has an average pore size that is smaller than layer 61A1 and larger than layer 61A3, and layer 61A3 has the smallest average pore size. This makes it possible to suppress the increase in flow path resistance in the phosphor layer 11 and increase the capillary force toward the light-emitting portion of the phosphor layer 11. As a result, the maximum amount of heat to be transported can be increased.

[0147] The coolant conveying member 12 is used to carry the coolant 13 to the phosphor layer 61. It is preferable that the coolant conveying member 12 is formed as a continuous foam type porous layer like the phosphor layer 61. It is preferable that the average pore size of the coolant conveying member 12 is larger than that of the phosphor layer 61.

[0148] The wavelength conversion element 1G according to the present embodiment is a so-called reflective wavelength conversion element, which extracts the fluorescence FL by, for example, reflecting the fluorescence FL in the same direction as the input direction of the excitation light EL. The fluorescence FL is emitted from the phosphor layer 61 irradiated by the excitation light EL. Therefore, it is preferable that the coolant delivery member 12 further has light reflectivity. For example, it is preferable to use an inorganic material such as a metal material or a ceramic material. Examples of materials included in the coolant delivery member 12 include a single metal such as aluminum (Al), copper (Cu), molybdenum (Mo), tungsten (W), cobalt (Co), chromium (Cr), platinum (Pt), tantalum (Ta), lithium (Li), zirconium (Zr), ruthenium (Ru), rhodium (Rh) or palladium (Pd) or an alloy including one or more of the above metals. The coolant delivery member 12 includes a sintered ceramic compact, a sintered metal or a porous metal, and the porous metal includes, for example, the above materials.

[0149] The coolant 13 circulates between the phosphor layer 61 and the coolant conveying member 12 to cool the phosphor particles heated by the irradiation of the excitation light EL. For example, it is preferable to use a liquid having a large latent heat for the coolant 13. In addition, the coolant 13 circulates through the gaps formed in the phosphor layer 61 and the coolant conveying member 12. Therefore, it is preferable that the coolant 13 has a low viscosity. Specific examples of the coolant 13 include water, acetone, methanol, naphthalene, benzene, and the like.

[0150] One surface of the housing 20 includes a material having light transmittance. A sealed space (internal space) may be formed in the housing 20. As described above, the housing 20 includes a housing portion 21 and a cover glass 22, the cover glass 22 is combined with the housing portion 21 to form a sealed space and the cover glass 22 corresponds to one surface described above. The cover glass 22 corresponds to a specific example of a "sealing portion" according to the present disclosure. The housing portion 21 accommodates the phosphor layer 11, the coolant delivery member 12, and the coolant 13. The phosphor layer 11 and the coolant delivery member 12 are arranged so that the phosphor layer 11 faces the cover glass 22 side (for example, at Figure 1 As the material included in the housing 20, for example, aluminum, copper, stainless steel, low carbon steel, alloy materials thereof, etc. are used for the accommodating portion 21. In addition to the glass substrate, for example, soda glass, quartz, sapphire glass, crystal, etc. are used for the cover glass 22. In addition, in the case where the light source portion 110 outputs laser light with low output power, resins such as polyethylene terephthalate (PET), silicone resin, polycarbonate, and acrylic are used.

[0151] The surface of the housing 20 opposite to the one surface or the rear surface of the accommodation portion 21 is provided with a heat dissipation member 23. The heat dissipation member 23 is used to cool the accommodation portion 21. This causes the vapor of the coolant 13 to condense on the inner surface side of the accommodation portion 21, thereby causing a phase change to become liquid, and the liquid is transported to the phosphor layer 61 by the coolant transport member 12. A plurality of heat dissipation fins may be used as the heat dissipation member 23, but is not limited thereto. For example, a Peltier element or a water cooling element may be used as, for example, the heat dissipation member 23.

[0152] In the case where both the phosphor layer 61 and the coolant delivery member 12 are formed by using a sintered compact, the predetermined parameters in the manufacturing step of each of the sintered compacts are controlled to provide a desired average pore size, as described in the first embodiment described above. For the phosphor layer 61 in which a plurality of layers (the first layer 61A (61A1, 61A2, and 61A3) and the second layer 61B) having different average pore sizes are stacked, for example, phosphor particles having a predetermined particle size corresponding to the corresponding layers 61A1, 61A2, and 61A3 are separated by classifying the phosphor (step S101), and then sintered phosphors having a desired average particle size are produced respectively by steps S102 to S105 as in the present embodiment. Thereafter, the respective sintered phosphors are stacked, thereby completing the phosphor layer 61 in which the average pore size gradually decreases along the direction in which the coolant 13 flows. It should be noted that the average pore size of the voids (pores) formed in the phosphor layer 61 is proportional to the particle size of the phosphor particles included in the phosphor layer 61. The larger the particle size of the phosphor particles used, the larger the average pore size of the resulting phosphor layer 61 .

[0153] The phosphor layer 61 can also be manufactured by using the following method. For example, phosphor particles each having a desired particle size are selected by classifying the phosphor. A sheet having phosphor particles set in a mold is molded and calcined to obtain a desired pore size spatial distribution. This uniformly forms the various layers (the first layer 61A (layers 61A1, 61A2, and 61A3)) included in the phosphor layer 61 along the direction in which the coolant 13 flows. The average pore size of the phosphor layer 61 gradually decreases. It should be noted that in addition to classification, the particle size of the phosphor particles can also be adjusted by utilizing manufacturing conditions.

[0154] The cooling cycle of the wavelength conversion element 1G according to the present embodiment is described. First, in the case where the phosphor layer 61 is irradiated with the excitation light EL, the phosphor particles generate heat. The coolant 13 is evaporated by the heat and takes away the latent heat at the same time. Fig.21As shown, in the case where the middle part of the phosphor layer 61 is irradiated with the excitation light EL, the evaporated coolant 13 moves to the outer peripheral side (space 12S) of the phosphor layer 61 in the form of vapor. The vapor that has moved to the space 12S is dissipated latent heat by the inner wall of the accommodating portion 21 and liquefied again. The liquefied coolant 13 is transported to the phosphor layer 61 by the capillary force of the coolant transport member 12, and is immediately moved to the heat-generating portion (light-emitting portion) of the phosphor layer 61 (e.g., layer 61A3) by the capillary force of the phosphor layer 61. By repeating this process, the heat generated by the radiation of the excitation light EL is discharged to the coolant transport member 12.

[0155] (3-2. Actions and Effects)

[0156] As described above, in recent years, laser excited phosphors have been used as light sources in projection display devices (projectors). Laser excited phosphor light sources have problems in increasing the cooling efficiency of the phosphor. Two-phase flow cooling technology (phase change cooling technology) using latent heat has attracted attention. The two-phase flow cooling technology allows the coolant to directly cool the phosphor or the luminescent particles of the luminescent area. However, the two-phase flow cooling technology has the problem that the phosphor is contaminated by eluents and the light output power is reduced due to the contamination, and the eluents come from the materials included in the sealed shell that encapsulates the phosphor and the coolant.

[0157] In contrast, the present embodiment has a multilayer structure in which the average pore size on the coolant delivery member 12 side and the cover glass 22 side are different. The cover glass 22 side includes a light-emitting portion that converts the radiated excitation light EL into the fluorescent light FL. Specifically, a first layer 61A having an average pore size smaller than a predetermined average pore size of the coolant delivery member 12 and a second layer 61B containing a light-emitting portion and having a higher particle density than the first layer 61A are stacked in sequence starting from the coolant delivery member 12 side. This promotes the flow of the coolant 13 into the phosphor layer 61 and makes it possible to improve the cooling efficiency of the phosphor layer 61. In addition, the particle density of the light-emitting portion and the area near the light-emitting portion (the second layer 61B in the present embodiment) increases. Preferably, the light-emitting portion and the area near the light-emitting portion (the second layer 61B in the present embodiment) have a non-porous structure. This suppresses foreign matter included in the coolant 13 (such as eluted matter from the material included in the housing 20) from entering the light-emitting portion, and makes it possible to prevent the light-emitting portion and the area near the light-emitting portion from being contaminated.

[0158] In addition, the two-phase flow cooling technology circulates the coolant by using the capillary force caused by the voids (pores) in the phosphor layer, but the collision between the flow of the coolant in the gaseous state and the flow of the liquid coolant becomes the flow resistance in the layer. In the case of releasing more heat, the coolant in the layer circulates at a higher speed. The flow resistance caused by the above collision increases significantly. As a result, the total flow resistance exceeds the total capillary force, resulting in drying.

[0159] In contrast, in the present embodiment, for example, Fig.24 As shown, the first layer 61A includes multiple layers (e.g., three layers 61A1, 61A2, and 61A3) having different average pore sizes. The multiple layers are stacked so that the average pore size gradually increases in the direction in which the coolant 13 flows. This makes it possible to suppress an increase in flow path resistance and increase capillary force.

[0160] Fig.25 Arranged in such a way that will have The flow path resistance in the case where a sintered cylindrical phosphor having a height of 1 mm and 3 mm is divided into a plurality of layers, each of the plurality of layers has 1 mm in the height direction, and the particle size distribution of the phosphor particles is set as follows. Fig.25 Samples A (20 / 20 / 20), B (20 / 50 / 50), and C (20 / 50 / 100) in FIG. 4 show that gradually decreasing the particle size distribution (average pore size) toward the light-emitting portion allows the flow path resistance to be reduced. In sample A (20 / 20 / 20), all layers have an average particle size of 20 μm. In sample B (20 / 50 / 50), the layer including the light-emitting portion has an average particle size of 20 μm, and the other two layers have an average particle size of 50 μm. In sample C (20 / 50 / 100), the layers have an average particle size of 20 μm, 50 μm, and 100 μm from the layer including the light-emitting portion.

[0161] As described above, the wavelength conversion element 1G according to the present embodiment is provided with the phosphor layer 61 having a porous structure in which the first layer 61A and the second layer 61B are stacked in order from the coolant conveying member 12 side. The average pore size of the second layer 61B including the light emitting portion that converts the excitation light EL into the fluorescent light FL is smaller than the average pore size of the first layer 61A provided on the coolant conveying member 12 side. Alternatively, the second layer 61B has a non-porous structure. This improves the cooling performance and prevents foreign matter from contaminating the light emitting portion, thereby making it possible to realize a wavelength conversion element with high output power and high reliability.

[0162] In addition, in the present embodiment, the first layer 61A provided on the coolant transport member 12 side has a multilayer structure including, for example, a plurality of layers (e.g., layer 61A1, layer 61A2, and layer 61A3) whose average pore diameters gradually decrease along the flow of the coolant. This makes it possible to suppress an increase in flow path resistance and increase capillary force. This further improves cooling performance and makes it possible to further increase output power.

[0163] <4. Modifications>

[0164] In the above-described second embodiment or the like, the wavelength conversion element 1G including the phosphor layer 61 having a cylindrical shape and having a multilayer structure in which a plurality of layers are stacked in the Z-axis direction has been described, but the phosphor layer 61 may be configured as follows.

[0165] (4-1. Modification 7)

[0166] Fig.26 Another example of the cross-sectional structure of the main part of the wavelength conversion element 1G serving as a modified example of the second embodiment is schematically shown. Fig.26 The phosphor layer 61 shown has a non-porous second layer 61B that is limited to the minimum area that contributes to light emission. Specifically, the phosphor layer 61 has a configuration in which the side surfaces of the layers 61A2 and 61A3 included in the second layer 61B and the first layer 61A are covered by the layer 61A1 having the largest average pore size. In other words, the phosphor layer 61 according to the present modification is configured to have an area having an average pore size larger than the average pore size of the light-emitting portion at the side surface of the phosphor layer 61 containing the light-emitting portion in a plan view.

[0167] As described above, since a region having an average pore size larger than that of the second layer 61B is provided around the second layer 61B containing the light-emitting portion in a plan view, the coolant 13 that is evaporated by the heat generated by the phosphor particles in the light-emitting portion and the region near the light-emitting portion and becomes a gas phase has a smaller flow resistance when it is discharged into the space 12S. In addition, by increasing the average pore size of the second layer 61B containing the light-emitting portion, the flow of the gaseous coolant 13 and the liquid coolant 13 is adjusted by the balance of the capillary force, so that the inflow of the coolant 13 from the periphery of the light-emitting portion (for example, the outer periphery of the second layer 61B away from the light-emitting portion according to the second embodiment described above) to the light-emitting portion is suppressed. This suppresses the increase in flow resistance caused by the interface between the respective flows and makes it possible to further improve the output power and reliability.

[0168] (4-2. Modification 8)

[0169] Fig. 27 Another example of the cross-sectional structure of the main part of the wavelength conversion element 1G serving as a modified example of the second embodiment is schematically shown. Fig. 27 The phosphor layer 61 shown has a second layer 61B limited to the minimum area contributing to light emission as in the above-described embodiment 7, and has a configuration in which the side surfaces of the layers 61A2 and 61A3 included in the first layer 61A are processed into a tapered shape and a layer 61C having an average pore size larger than that of the layer 61A is provided at these side surfaces including the side surface of the second layer 61B. This layer 61C corresponds to a specific example of a “coolant discharge area” according to the present disclosure.

[0170] As described above, the second layer 61B including the light emitting portion has a minimum diameter that contributes to the light emitting method. In addition, each layer (layers 61A2 and 61A3) between the layer 61A and the second layer 61B has a cone shape. The layer 61C having an average pore diameter greater than the average pore diameter of the layer 61A is provided at the side surface of the layers 61A2 and 61A3 and the second layer 61B. This makes it possible to further reduce the flow resistance of the coolant 13 in the gaseous state. This makes it possible to expect an increase in the maximum amount of heat to be transported and to further improve the output power and reliability.

[0171] (4-3. Modification 9)

[0172] Fig.28 Another example of the cross-sectional structure of the main part of the wavelength conversion element 1G serving as a modified example of the second embodiment is schematically shown. Fig.28 The phosphor layer 61 shown is not provided with the layer 61C provided in the above-mentioned modification 8. There is no structure around the side surfaces of the layers 61A2 and 61A3 and the second layer 61B. This allows the coolant 13 that evaporates and becomes a gas phase due to the heat generated in the phosphor particles in the light-emitting portion and the area near the light-emitting portion to be directly discharged to the space 12S. Therefore, the flow path resistance of the gaseous coolant 13 can be further reduced. This makes it possible to expect a further increase in the maximum amount of heat to be transported.

[0173] (4-4. Modification 10)

[0174] Fig.29 Another example of a cross-sectional configuration of a main portion of a wavelength conversion element 1G serving as a modified example of the above-described second embodiment is schematically shown. Each of the layers 61A1, 61A2, 61A3, and 61C does not have to be formed by using phosphor particles. For example, each of the layers 61A1, 61A2, 61A3, and 61C can be formed by using a porous material having high thermal conductivity. Specifically, each of the layers 61A1, 61A2, 61A3, and 61C according to this modified example may include, for example, a sintered ceramic compact, a sintered metal, or a porous metal, the porous metal including the materials mentioned for the coolant delivery member 12. This makes it possible to further improve the heat dissipation performance. It should be noted that layer 61C does not have to be provided as in the above-described modified example 9.

[0175] (4-5. Modification 11)

[0176] Fig.30 Another example of the cross-sectional structure of the main part of the wavelength conversion element 1G used as a modified example of the second embodiment is schematically shown. The wavelength conversion element 1G may also be included in a transmission-type wavelength conversion element. In the case of a transmission-type wavelength conversion element, Fig.30As shown, openings H are provided at positions corresponding to the light emitting portions of the second layer 61B of the first layer 61A and the coolant transport member 12. This allows the fluorescence FL to be extracted from the side (e.g., the back cover 41A side) opposite to the incident side (e.g., the cover glass 42 side) of the excitation light EL.

[0177] It should be noted that in the case where the first layer 61A having voids (holes) inside is provided with the opening H as in the present modification, it is preferable that each of the side surfaces facing the opening H is non-porous. This makes it possible to prevent the coolant 13 that is evaporated by the heat generated by the phosphor particles in the light emitting portion and the area near the light emitting portion and becomes a gas phase from flowing into the opening H. This makes it possible to suppress a reduction in light extraction efficiency caused by droplets adhering to the opening.

[0178] (4-6. Modification 12)

[0179] Fig.31 Another example of the cross-sectional configuration of the main part of the wavelength conversion element 1G used as a modified example of the above-mentioned second embodiment is schematically shown. The wavelength conversion element 1G according to this modified example has a glass 71 provided in the opening H formed in the above-mentioned modified example 11. In this way, the glass 71 is provided in the opening H so that the coolant 13 in a gaseous state can be prevented from flowing into the opening H. Compared with the case of a non-porous side surface opposite to the opening H, this makes it easier to prevent the coolant 13 in a gaseous state from flowing into the opening.

[0180] It should be noted that it is sufficient as long as the glass 71 is a light-transmitting member. The glass is not restrictive. For example, sapphire or the like can be used. In addition, the second embodiment and modifications 7 to 12 described above can also be applied to, for example, Fig.11 and 13 The phosphor wheels shown (wavelength conversion elements 1D and 1E) are each rotatable about a rotation axis (eg, axis J51). Effects similar to those of the second embodiment and modifications 7 to 12 described above can be obtained.

[0181] (4-7. Modification 13)

[0182] Fig.32 An example of a cross-sectional configuration of a wavelength conversion element (wavelength conversion element 1H) according to a combination of the above-described first embodiment and the above-described second embodiment is schematically shown. The wavelength conversion element 1H according to this modification includes a phosphor layer 61 in which the average pore diameters of a surface 61S1 facing the cover glass 22 and a surface 61S2 facing the coolant delivery member 12 are different, for example, as in the above-described second embodiment. As in the above-described first embodiment, the protective layer 24 is provided on the inner wall of the accommodating portion 21.

[0183] In this way, the phosphor layer 61 is provided with an average pore size distribution that decreases, for example, along the flow of the coolant 13, and the inner wall of the housing 21 is provided with the protective layer 24 that prevents the housing 21 and the coolant 13 from directly contacting each other. This makes it possible to further prevent the light emitting portion from being contaminated by elution of the material included in the housing 21 in the coolant 13, etc. Therefore, a wavelength conversion element with higher output power and higher reliability can be realized.

[0184] It should be noted that an example of a combination of the above-described first embodiment and the above-described second embodiment has been described in this modification, but the above-described first and second embodiments and modifications 1 to 12 may be combined with each other. For example, the above-described modification 5 and the above-described second embodiment may be combined, and the protective layer 24 of the above-described wavelength conversion element 1G may also be formed on the cover glass 22 side. This makes it possible to obtain an effect of suppressing stray light in addition to the effect according to this modification.

[0185] <5. Application Examples>

[0186] (Configuration Example 1 of Light Source Module)

[0187] Fig.33 1 is a schematic diagram showing the overall configuration of an example of a light source module 100 (light source module 100A) included in, for example, a projector 1000 described below. The light source module 100A includes a wavelength conversion element 1 (any of the wavelength conversion elements 1A to 1H described above), a light source section 110, a polarization beam splitter (PBS) 112, a quarter wave plate 113, and a focusing optical system 114. The above-mentioned respective components included in the light source module 100A are arranged on the optical path of light (combined light Lw) emitted from the wavelength conversion element 1 in the order of the focusing optical system 114, the quarter wave plate 113, and the PBS 112 from the wavelength conversion element 1 side. The light source section 110 is arranged at a position opposite to one light incident surface of the PBS 112 in a direction orthogonal to the optical path of the combined light Lw.

[0188] The light source unit 110 includes a solid-state light emitting element that emits light having a predetermined wavelength. In this embodiment, a semiconductor laser element that oscillates excitation light EL (for example, a blue laser having a wavelength of 445 nm or 455 nm) is used as the solid-state light emitting element. The light source unit 110 emits linearly polarized (S-polarized) excitation light EL.

[0189] It should be noted that, in the case where the light source section 110 includes a semiconductor laser element, the excitation light EL having a predetermined output power can be obtained by one semiconductor laser element, or by combining a plurality of lights output from a plurality of semiconductor laser elements. In addition, the wavelength of the excitation light EL is not limited to the above-mentioned values. Any wavelength can be used as long as the wavelength falls within the light wavelength band referred to as blue light.

[0190] The PBS 112 is used to separate the excitation light EL incident from the light source section 110 and the combined light Lw incident from the wavelength conversion element 1. Specifically, the PBS 112 reflects the excitation light EL incident from the light source section 110 toward the quarter wave plate 113. In addition, the PBS 112 transmits the combined light Lw incident from the wavelength conversion element 1 through the focusing optical system 114 and the quarter wave plate 113. The transmitted combined light Lw is input to the illumination optical system 200 (described below).

[0191] The quarter wave plate 113 is a phase difference element that causes the incident light to produce a phase difference of π / 2. In the case where the incident light is linearly polarized light, the linearly polarized light is converted into circularly polarized light. In the case where the incident light is circularly polarized light, the circularly polarized light is converted into linearly polarized light. The linearly polarized excitation light EL emitted from the polarization beam splitter 112 is converted into circularly polarized excitation light EL by the quarter wave plate 113. In addition, the circularly polarized excitation light component contained in the combined light Lw emitted from the wavelength conversion element 1 is converted into linearly polarized light by the quarter wave plate 113.

[0192] The focusing optical system 114 focuses the excitation light EL emitted from the quarter wave plate 113 in a predetermined spot diameter, and emits the focused excitation light EL toward the wavelength conversion element 1. In addition, the focusing optical system 114 converts the combined light Lw emitted from the wavelength conversion element 1 into parallel light, and emits the parallel light toward the quarter wave plate 113. It should be noted that the focusing optical system 114 may include, for example, one collimating lens or may have a configuration in which incident light is converted into parallel light by using a plurality of lenses.

[0193] Note that the configuration of the optical component that separates the excitation light EL incident from the light source section 110 and the combined light Lw emitted from the wavelength conversion element 1 is not limited to that of the PBS 112. Any optical component may be used as long as its configuration allows the above-described light separation operation.

[0194] (Configuration Example 2 of Light Source Module)

[0195] Fig.34 1 is a schematic diagram showing the overall configuration of another example (light source module 100B) of the light source module 100 .

[0196] The light source module 100B includes a wavelength conversion element 1, a light source section 110, a dichroic mirror 115, and a focusing optical system 114. The above-mentioned components included in the light source module 100C are arranged on the optical path of the light (combined light Lw) emitted from the wavelength conversion element 1 in the order of the focusing optical system 114, the quarter wave plate 113, and the PBS 112 from the wavelength conversion element 1 side. The light source section 110 is arranged at a position in a direction orthogonal to the optical path of the combined light Lw, and the excitation light EL is reflected toward the wavelength conversion element 1 by the dichroic mirror 115.

[0197] (Configuration Example 3 of Light Source Module)

[0198] Fig.35 100 is a schematic diagram of the overall structure of another example (light source module 100C) of the light source module 100 .

[0199] The light source module 100C includes a wavelength conversion element 1, a light source section 110, a dichroic mirror 115, a quarter wave plate 113, and a focusing optical system 114. The above-mentioned components included in the light source module 100C are arranged in the order of the focusing optical system 114, the quarter wave plate 113, and the dichroic mirror 115 from the wavelength conversion element 1 side on the optical path of the light (combined light Lw) emitted from the wavelength conversion element 1. A color mirror 116 is further arranged on the front surface of the wavelength conversion element 1 (for example, on the cover glass 22). This reflects a part of the excitation light EL (blue light). The reflected excitation light EL (blue light) is combined with the fluorescent light FL (yellow light) to produce white light.

[0200] (Configuration Example 4 of Light Source Module)

[0201] Fig.36 1 is a schematic diagram of the overall structure of another example (light source module 100D) of the light source module 100 .

[0202] The light source module 100D includes a wavelength conversion element 1, a diffusion plate 131, a light source unit 110 that emits excitation light or laser, lenses 117 to 120, a dichroic mirror 121, and a reflector 122. The diffusion plate 131 is rotatably supported by an axis J131, and is rotated and driven, for example, by a motor 132. The light source unit 110 includes a first laser group 110A and a second laser group 110B. Each of a plurality of semiconductor laser elements 111A oscillates excitation light (for example, a wavelength of 445nm or 455nm), and the plurality of semiconductor laser elements 111A are arranged in the first laser group 110A. Each of a plurality of semiconductor laser elements 111B oscillates blue laser (for example, a wavelength of 465nm), and the plurality of semiconductor laser elements 111B are arranged in the second laser group 110B. Here, for the sake of simplicity, the excitation light oscillated from the first laser group 110A is defined as EL1 , and the blue laser light (which is simply referred to as blue light) oscillated from the second laser group 110B is defined as EL2 .

[0203] In the light source module 100D, the wavelength conversion element 1 is arranged to incident the excitation light EL1 to the phosphor layer 11. The excitation light has passed through the lens 117, the dichroic mirror 121 and the lens 118 in sequence from the first laser group 110A. The fluorescence FL from the wavelength conversion element 1 is reflected by the dichroic mirror 121. After that, the fluorescence FL passes through the lens 119 and travels to the outside. In other words, the fluorescence FL travels to the illumination optical system 200 described below. The diffuser 131 diffuses the blue light EL2 from the second laser group 110B passing through the reflector 122. The blue light EL2 diffused by the diffuser 131 passes through the lens 120 and the dichroic mirror 121. After that, the blue light EL2 passes through the lens 119 and travels to the outside. In other words, the blue light EL2 travels to the illumination optical system 200.

[0204] (Projector Configuration Example 1)

[0205] Fig.37 is a schematic diagram showing the overall structure of the projector 1000. The projector 1000 includes Fig.33 The light source module 100 or the like shown (any of the light source modules 100A to 100D described above) serves as a light source optical system. Note that the following description takes a reflective 3LCD projector in which light modulation is performed by a reflective liquid crystal panel (LCD) as an example.

[0206] like Fig.37 As shown, the projector 1000 includes the above-mentioned light source module 100, an illumination optical system 200, an image forming unit 300 and a projection optical system 400 (projection optical system) in this order.

[0207] The illumination optical system 200 includes, from a position close to the light source module 100, for example, a fly-eye lens 210 (210A and 210B), a polarization conversion element 220, a lens 230, dichroic mirrors 240A and 240B, reflecting mirrors 250A and 250B, lenses 260A and 260B, a dichroic mirror 270, and polarization plates 280A to 280C.

[0208] The fly-eye lens 210 (210A and 210B) realizes a uniform distribution of the illumination of the white light from the light source module 100. The polarization conversion element 220 is used to align the polarization axis of the incident light with a predetermined direction. For example, light other than P polarized light is converted into P polarized light. The lens 230 converges the light from the polarization conversion element 220 toward the dichroic mirrors 240A and 240B. Each of the dichroic mirrors 240A and 240B selectively reflects light in a predetermined wavelength range and selectively transmits a variety of light in other wavelength ranges. For example, the dichroic mirror 240A mainly reflects red light in the direction of the reflector 250A. In addition, the dichroic mirror 240B mainly reflects blue light in the direction of the reflector 250B. Therefore, it is mainly green light that passes through both the dichroic mirrors 240A and 240B and travels to the reflective polarizing plate 310C (described below) of the image forming unit 300. Reflector 250A reflects light (mainly red light) from dichroic mirror 240A toward lens 260A, and reflector 250B reflects light (mainly blue light) from dichroic mirror 240B toward lens 260B. Lens 260A transmits light (mainly red light) from reflector 250A and converges the light on dichroic mirror 270. Lens 260B transmits light (mainly blue light) from reflector 250B and converges the light on dichroic mirror 270. Dichroic mirror 270 selectively reflects green light and selectively transmits a variety of lights in other wavelength ranges. Here, dichroic mirror 270 transmits the red light component in the light from lens 260A. In the case where the light from lens 260A includes a green light component, the green light component is reflected toward polarizing plate 280C. Each of polarizing plates 280A to 280C includes a polarizer having a polarization axis in a predetermined direction. For example, in the case where light is converted into P-polarized light by the polarization conversion element 220 , each of the polarization plates 280A to 280C transmits the P-polarized light and reflects the S-polarized light.

[0209] The image forming section 300 includes reflective polarizing plates 310A to 310C, reflective liquid crystal panels 320A to 320C (light modulation elements), and a dichroic prism 330 .

[0210] The reflective polarizing plates 310A to 310C transmit a plurality of lights (e.g., a plurality of P-polarized lights) having the same polarization axis as the polarization axis of the plurality of polarized lights from the polarizing plates 280A to 280C, respectively, and reflect a plurality of lights (a plurality of S-polarized lights) having other polarization axes. Specifically, the reflective polarizing plate 310A transmits the P-polarized red light from the polarizing plate 280A in the direction of the reflective liquid crystal panel 320A. The reflective polarizing plate 310B transmits the P-polarized blue light from the polarizing plate 280B in the direction of the reflective liquid crystal panel 320B. The reflective polarizing plate 310C transmits the P-polarized green light from the polarizing plate 280C in the direction of the reflective liquid crystal panel 320C. In addition, the P-polarized green light that passes through both the dichroic mirrors 240A and 240B and is incident on the reflective polarizing plate 310C passes through the reflective polarizing plate 310C as it is and is incident on the dichroic prism 330. Furthermore, the reflective polarizing plate 310A reflects the S-polarized red light from the reflective liquid crystal panel 320A and causes the S-polarized red light to be incident on the dichroic prism 330. The reflective polarizing plate 310B reflects the S-polarized blue light from the reflective liquid crystal panel 320B and causes the S-polarized blue light to be incident on the dichroic prism 330. The reflective polarizing plate 310C reflects the S-polarized green light from the reflective liquid crystal panel 320C and causes the S-polarized green light to be incident on the dichroic prism 330.

[0211] The reflective liquid crystal panels 320A to 320C perform spatial modulation on red light, blue light, or green light, respectively.

[0212] The dichroic prism 330 combines the red light, the blue light, and the green light incident thereon, and emits the combined light toward the projection optical system 400 .

[0213] The projection optical system 400 includes lenses L410 to L450 and a mirror M400. The projection optical system 400 enlarges the light emitted from the image forming unit 300 and projects it onto a screen 460 or the like.

[0214] (Operation of light source module and projector)

[0215] Next, refer to Fig.33 and 37 The operation of the projector 1000 including the light source module 100 is described.

[0216] First, the excitation light EL is oscillated toward the PBS from the light source section 110. The excitation light EL is reflected by the PBS 112 and then sequentially passes through the quarter-wave plate 113 and the condensing optical system 114. The wavelength conversion element 1A is irradiated with the excitation light EL.

[0217] In the wavelength conversion element 1A, a portion of the excitation light EL (blue light) is absorbed in the phosphor layer 11 and converted into light in a predetermined wavelength band (fluorescent light FL; yellow light). The fluorescent light FL emitted from the phosphor layer 11 and the portion of the excitation light EL that is not absorbed in the phosphor layer 11 are scattered together and reflected toward the side of the focusing optical system 114. As a result, the fluorescent light FL and a portion of the excitation light EL are combined to generate white light in the wavelength conversion element 1A. This white light (combined light Lw) is emitted toward the focusing optical system 114.

[0218] After that, the combined light Lw passes through the condensing optical system 114 , the quarter-wave plate 113 , and the PBS 112 and enters the illumination optical system 200 .

[0219] Combined light Lw incident from the light source module 100 (light source module 100A) sequentially passes through the fly-eye lenses 210 ( 210A and 210B), the polarization conversion element 220 , and the lens 230 , and then reaches the dichroic mirrors 240A and 240B.

[0220] The color separation mirror 240A mainly reflects red light. The red light passes through the reflector 250A, the lens 260A, the color separation mirror 270, the polarizing plate 280A and the reflective polarizing plate 310A in sequence and reaches the reflective liquid crystal panel 320A. The red light is subjected to spatial modulation at the reflective liquid crystal panel 320A, and then is reflected by the reflective polarizing plate 310A to be incident on the color separation prism 330. It should be noted that in the case where the light reflected by the color separation mirror 240A toward the reflector 250A includes a green light component, the green light component is reflected by the color separation mirror 270 and passes through the polarizing plate 280C and the reflective polarizing plate 310C in sequence to reach the reflective liquid crystal panel 320C. The color separation mirror 240B mainly reflects blue light. The blue light is incident on the color separation prism 330 through a similar process. The green light that has passed through the color separation mirrors 240A and 240B is also incident on the color separation prism 330.

[0221] The red light, blue light, and green light incident on the dichroic prism 330 are combined and then emitted as image light toward the projection optical system 400. The projection optical system 400 amplifies the image light from the image forming section 300 and projects it onto a screen 500 or the like.

[0222] (Projector Configuration Example 2)

[0223] Fig.38 1 is a schematic diagram showing a configuration example of a transmissive 3LCD projection display device (projector 1000) that performs light modulation by a transmissive liquid crystal panel. Projector 1000 includes, for example, a light source module 100, an image generation system 600 including an illumination optical system 610 and an image generation unit 630, and a projection optical system 700.

[0224] The illumination optical system 610 includes, for example, an integrating element 611, a polarization conversion element 612, and a condensing lens 613. The integrating element 611 includes a first fly-eye lens 611A including a plurality of microlenses arranged two-dimensionally and a second fly-eye lens 611B including a plurality of microlenses arranged in one-to-one association with the microlenses.

[0225] The light (parallel light) incident on the integrator element 611 from the light source module 100 is divided into a plurality of light beams by the microlenses of the first fly-eye lens 611A. Images of these light beams are formed on the respective corresponding microlenses of the second fly-eye lens 611B. The respective microlenses of the second fly-eye lens 611B serve as secondary light sources, and the polarization conversion element 612 is irradiated with a plurality of parallel lights having uniform brightness as incident light.

[0226] The integrator element 611 has a function of adjusting the incident light from the light source module 100 that illuminates the polarization conversion element 612 to light having a uniform brightness distribution as a whole.

[0227] The polarization conversion element 612 has a function of making the incident light entering through the integrator element 611 etc. have a uniform polarization state. For example, the polarization conversion element 612 emits outgoing light including blue light Lb, green light Lg, and red light Lr through a lens etc. provided on the outgoing side of the light source module 100 .

[0228] The illumination optical system 610 also includes a dichroic mirror 614 and a dichroic mirror 615, a mirror 616, a mirror 616 and a mirror 618, a relay lens 619 and a relay lens 620, a field lens 621R, a field lens 621G and a field lens 621B, liquid crystal panels 631R, 631G and 631B used as an image generating unit 630, and a dichroic prism 632.

[0229] The dichroic mirror 614 and the dichroic mirror 615 each have the property of selectively reflecting colored light in a predetermined wavelength range and transmitting light in other wavelength ranges. For example, the dichroic mirror 614 selectively reflects the red light Lr. The dichroic mirror 615 selectively reflects the green light Lg of the green light Lg and the blue light Lb that have passed through the dichroic mirror 614. The remaining blue light Lb passes through the dichroic mirror 615. This separates the light (e.g., white combined light Lw) emitted from the light source module 100 into a plurality of colored lights of different colors.

[0230] The separated red light Lr is reflected by the mirror 616 and passes through the field lens 621R to be collimated. Thereafter, the red light Lr is incident on the liquid crystal panel 631R to modulate the red light. The green light Lg passes through the field lens 621G to be collimated, and thereafter, the green light Lg is incident on the liquid crystal panel 631G to modulate the green light. The blue light Lb passes through the relay lens 619 and is reflected by the mirror 617. The blue light Lb further passes through the relay lens 620 and is reflected by the mirror 618. The blue light Lb reflected by the mirror 618 passes through the field lens 621B to be collimated. Thereafter, the blue light Lb is incident on the liquid crystal panel 631B to modulate the blue light Lb.

[0231] The liquid crystal panels 631R, 631G and 631B are electrically coupled to a signal source (such as a PC, etc.) not shown in the figure, which supplies an image signal including image information. The liquid crystal panels 631R, 631G and 631B modulate the incident light for each pixel based on the image signals of each color provided and generate a red image, a green image and a blue image respectively. The modulated light of each color (the formed image) is emitted to the color separation prism 632 and combined together. The color separation prism 632 overlaps and combines the light of each color incident from three directions and emits the combined light toward the projection optical system 700.

[0232] The projection optical system 700 includes, for example, a plurality of lenses, etc. The projection optical system 700 amplifies the light emitted from the image generation system 600 and projects the light onto the screen 500 .

[0233] Although the present disclosure has been described with reference to the first and second embodiments and Modifications 1 to 13, the present disclosure is not limited to the above embodiments, etc. The present disclosure can be modified in various ways. For example, the material, thickness, etc. of each layer described in the above embodiments are only examples, but are not limited thereto. Other materials and thicknesses may be used.

[0234] In addition, a device other than the above-mentioned projector 1000 may be configured as a projection display device according to the present technology. For example, an example has been described in which a reflective liquid crystal panel or a transmissive liquid crystal panel is used as a light modulation element in the above-mentioned projector 1000, but the present technology can also be applied to a projector including a digital micro-mirror device (DMD: Digital Micro-mirror Device) or the like.

[0235] In addition, in the present technology, the wavelength conversion element 1, the light source module 100, etc. according to the present technology can be included in a device other than a projection display device. For example, the light source module 100 according to the present disclosure can be used for lighting applications and can be applied to, for example, a lighting lamp for a car and a light source for lighting.

[0236] It should be noted that the present technology may also have the following configuration. This first technology provides a protective layer at least on a portion of the inner wall of the shell that encapsulates the phosphor layer, the coolant, and the coolant delivery component. This suppresses contact between the coolant and the shell. According to the second technology having the following configuration, the average pore size of the voids distributed in the phosphor layer having a porous structure changes from one surface of the light-emitting portion to another surface. This improves the inflow efficiency of the coolant toward the phosphor layer and reduces the entry of foreign matter into the light-emitting portion and the area near the light-emitting portion. This makes it possible to provide a wavelength conversion element that can improve the output power and reliability. It should be noted that the effects described herein are not necessarily restrictive, but may include any effect described in the present disclosure. [1]

[0238] A wavelength conversion element, comprising:

[0239] A phosphor layer containing a plurality of phosphor particles and having voids therein;

[0240] a coolant for cooling the phosphor layer;

[0241] A coolant delivery member disposed in contact with the phosphor layer and circulating the coolant; and

[0242] A housing encapsulates the phosphor layer, the coolant, and the coolant delivery member, and the housing has a protective layer on at least a portion of an inner wall thereof. [2]

[0244] The wavelength conversion element according to [1], wherein

[0245] The housing has a housing portion and a sealing portion, the housing portion housing the phosphor layer, the coolant, and the coolant delivery member, the sealing portion having light transmittance and forming an internal space in the housing by being combined with the housing portion, and

[0246] The protective layer is arranged on the inner wall of the accommodation portion. [3]

[0248] The wavelength conversion element according to [2], wherein the protective layer is further provided in a region other than a region facing the phosphor layer on one surface facing the sealing portion in the internal space. [4]

[0250] The wavelength conversion element according to [2] or [3], wherein the protective layer on the accommodation portion side is provided in a region other than a region facing the phosphor layer. [5]

[0252] The wavelength conversion element according to any one of [1] to [4], wherein the protective layer is further provided on a surface of the coolant transporting member. [6]

[0254] The wavelength conversion element according to any one of [1] to [5], wherein the protective layer includes a material or a surface structure having a high affinity for the coolant. [7]

[0256] The wavelength conversion element according to any one of [1] to [6], wherein the protective layer includes a single-layer film or a multi-layer film. [8]

[0258] The wavelength conversion element according to any one of [1] to [7], wherein the protective layer includes silicon oxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), or titanium oxide (TiO 2 ). [9]

[0260] The wavelength conversion element according to any one of [1] to [7], wherein the protective layer contains a metal material having a standard electrode potential higher than 0.35 V.

[10]

[0262] The wavelength conversion element according to any one of [1] to [7], wherein the protective layer includes gold (Au), silver (Ag), or stainless steel.

[11]

[0264] The wavelength conversion element according to any one of [1] to

[10] , wherein

[0265] The coolant circulates by capillary force generated in the phosphor layer and the coolant transport member, and

[0266] A capillary force in the phosphor layer is greater than a capillary force in the coolant transporting member.

[12]

[0268] The wavelength conversion element according to any one of [1] to

[11] ,

[0269] The coolant delivery component has a light-reflecting

[13]

[0271] The wavelength conversion element according to any one of [1] to

[12] , wherein the phosphor layer has a space between itself and the side wall of the housing.

[14]

[0273] The wavelength conversion element according to any one of [1] to

[13] , wherein the phosphor layer has a continuous foam type porous structure.

[15]

[0275] The wavelength conversion element according to any one of [1] to

[14] , wherein the phosphor layer includes a ceramic phosphor.

[16]

[0277] The wavelength conversion element according to any one of [1] to

[15] , wherein the coolant transporting member has a continuous foam type porous structure.

[17]

[0279] The wavelength conversion element according to any one of [1] to

[16] , wherein the coolant delivery member includes a sintered ceramic compact, a sintered metal, or a porous metal.

[18]

[0281] The wavelength conversion element according to any one of [1] to

[16] , wherein the coolant transporting member includes a plurality of particle or fiber structures.

[19]

[0283] The wavelength conversion element according to

[18] , wherein each of the plurality of particles included in the coolant transport member includes barium sulfate, titanium oxide, or aluminum oxide.

[20]

[0285] The wavelength conversion element according to

[18] , wherein the fiber structure included in the coolant transport member includes copper, aluminum, stainless steel, resin, glass or ceramic, or a combination of the above materials. [twenty one]

[0287] The wavelength conversion element according to any one of [1] to

[20] , wherein

[0288] The phosphor layer and the coolant delivery member each have a continuous foam type porous structure, and

[0289] The average pore size of the phosphor layer is smaller than the average pore size of the coolant delivery member. [twenty two]

[0291] The wavelength conversion element according to any one of [1] to

[21] , wherein the coolant conveying member has a flow path for conveying the coolant on its contact surface with the phosphor layer. [twenty three]

[0293] The wavelength conversion element according to any one of [1] to

[22] , wherein the phosphor layer is directly cooled by latent heat generated by evaporation of the coolant. [twenty four]

[0295] The wavelength conversion element according to any one of [2] to

[23] , wherein the housing portion has a heat dissipation member on the back surface.

[25]

[0297] The wavelength conversion element according to any one of [1] to

[24] , wherein the housing is a rotatable wheel member, and the phosphor layer has a ring shape.

[26]

[0299] The wavelength conversion element according to any one of [1] to

[25] , wherein:

[0300] When the phosphor layer and the coolant transport member are used in a state where their surfaces stand vertically, the capillary force (P) in the coolant transport member satisfies the following formula (1):

[0301] P≥head difference R0 (mmH2O)……(1),

[0302] (R0: distance from the light emitting portion in the phosphor layer to the inner side wall of the housing).

[27]

[0304] A wavelength conversion element, comprising:

[0305] A phosphor layer, the phosphor layer containing a plurality of phosphor particles and having a porous structure in which an average pore size changes from one surface toward a light-emitting portion of another surface;

[0306] a coolant for cooling the phosphor layer;

[0307] A coolant delivery member disposed in contact with the phosphor layer and circulating the coolant; and

[0308] A housing encapsulates the phosphor layer, the coolant, and the coolant delivery member.

[28]

[0310] The wavelength conversion element according to

[27] , wherein the phosphor layer has a plurality of voids, and the plurality of voids are distributed in such a manner that the average pore size gradually decreases from the one surface toward the light-emitting portion of the other surface.

[29]

[0312] The wavelength conversion element according to

[27] or

[28] , wherein at least the light-emitting portion of the phosphor layer does not include voids.

[30]

[0314] A wavelength conversion element according to any one of

[27] to

[29] , wherein the phosphor layer has a coolant discharge region around the light-emitting portion, the coolant discharge region having voids having an average pore size larger than voids near the other surface of the light-emitting portion.

[31]

[0316] The wavelength conversion element according to any one of

[27] to

[30] , wherein the phosphor layer has an inclined surface on at least a part of a side surface.

[32]

[0318] The wavelength conversion element according to any one of

[27] to

[31] , wherein

[0319] The phosphor layer has a first layer containing a plurality of phosphor particles, and a second layer made of a porous material that does not contribute to light emission, and

[0320] A plurality of voids whose pore diameters vary from the one surface toward the other surface are formed in the second layer.

[33]

[0322] The wavelength conversion element according to

[32] , wherein the second layer includes a sintered ceramic compact, a sintered metal, or a porous metal.

[34]

[0324] The wavelength conversion element according to any one of

[27] to

[33] , wherein the coolant conveying member is provided on the one surface of the phosphor layer and has an opening at a position facing the light emitting portion, and a light transmitting member is provided in the opening.

[35]

[0326] The wavelength conversion element according to

[34] , wherein the light-transmitting component includes glass or sapphire.

[36]

[0328] The wavelength conversion element according to any one of

[27] to

[35] , wherein the housing further has a protective layer on at least a portion of an inner wall thereof.

[0329] This application claims the priority based on Japanese Patent Application No. 2019-058236 filed in the Japan Patent Office on March 26, 2019, the entire contents of which are incorporated into this application by reference.

[0330] It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.

Claims

1. A wavelength conversion element, comprising: A phosphor layer containing a plurality of phosphor particles and having voids therein; a coolant for cooling the phosphor layer; A coolant conveying member disposed in contact with the phosphor layer and circulating the coolant; and a housing enclosing the phosphor layer, the coolant and the coolant delivery member, and the housing having a protective layer on at least a portion of its inner wall, wherein The phosphor layer has a multilayer structure including a plurality of layers, and average pore sizes of the plurality of layers gradually decrease along the flow of the coolant.

2. The wavelength conversion element according to claim 1, wherein The housing has a housing portion that houses the phosphor layer, the coolant, and the coolant delivery member, and a sealing portion that has light transmittance and forms an internal space in the housing by being combined with the housing portion, and The protective layer is arranged on the inner wall of the accommodation portion. 3 . The wavelength conversion element according to claim 2 , wherein the protective layer is provided in a region other than a region of the accommodation portion and the sealing portion that form the internal space and that faces the phosphor layer, and is further provided on a surface of the coolant conveying member. The wavelength conversion element according to claim 1 , wherein the protective layer comprises a metal material having a standard electrode potential higher than 0.35 V.

5. The wavelength conversion element according to claim 1, wherein The coolant circulates by capillary force generated in the phosphor layer and the coolant transport member, and A capillary force in the phosphor layer is greater than a capillary force in the coolant delivery member. The wavelength conversion element according to claim 1 , wherein the coolant delivery member has light reflectivity. 7 . The wavelength conversion element according to claim 1 , wherein the phosphor layer has a space between itself and a side wall of the housing.

8. The wavelength conversion element according to claim 1, wherein The phosphor layer and the coolant delivery member each have a continuous foam type porous structure, and The average pore size of the phosphor layer is smaller than the average pore size of the coolant delivery member. 9 . The wavelength conversion element according to claim 1 , wherein the coolant conveying member has a flow path for conveying the coolant on a contact surface thereof with the phosphor layer. 10 . The wavelength conversion element according to claim 1 , wherein the phosphor layer is directly cooled by latent heat generated by evaporation of the coolant. The wavelength conversion element according to claim 2 , wherein the housing portion has a heat dissipation member on a rear surface. 12 . The wavelength conversion element according to claim 1 , wherein the housing is a rotatable wheel member, and the phosphor layer has a ring shape.

13. The wavelength conversion element according to claim 1, wherein: When the phosphor layer and the coolant delivery member are used in a state where their surfaces stand vertically, the capillary force (P) in the coolant delivery member satisfies the following formula (1): P≥head difference R0 (mmH2O)……(1), Here, R0 is the distance from the light emitting portion in the phosphor layer to the inner side wall of the housing.

14. A wavelength conversion element, comprising: A phosphor layer, the phosphor layer containing a plurality of phosphor particles and having a porous structure with an average pore size changing from one surface toward a light-emitting portion of another surface, the phosphor layer having a plurality of voids, the plurality of voids being distributed in a manner that the average pore size gradually decreases from the one surface toward the light-emitting portion of the other surface; a coolant for cooling the phosphor layer; a coolant delivery member disposed in contact with the phosphor layer and circulating the coolant; and A housing encapsulates the phosphor layer, the coolant, and the coolant delivery member. 15 . The wavelength conversion element according to claim 14 , wherein at least the light emitting portion of the phosphor layer does not include a void. 16 . The wavelength conversion element according to claim 14 , wherein the phosphor layer has a coolant discharge region around the light emitting portion, the coolant discharge region having voids having an average pore diameter larger than voids near the other surface of the light emitting portion.

17. The wavelength conversion element according to claim 14, wherein The phosphor layer has a first layer containing a plurality of phosphor particles, and a second layer made of a porous material that does not contribute to light emission, and A plurality of voids having an average pore size varying from the one surface toward the other surface are formed in the second layer. 18 . The wavelength conversion element according to claim 14 , wherein the coolant conveying member is provided on the one surface of the phosphor layer and has an opening at a position facing the light emitting portion, and a light-transmitting member is provided in the opening.

19. The wavelength conversion element according to claim 14, wherein the housing further has a protective layer on at least a portion of an inner wall thereof.

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