Wavelength conversion device, light source device, and projector

Abstract

The present invention provides a wavelength conversion device, a light source device, and a projector that can easily maintain the temperature of the wavelength conversion element. [Solution] The wavelength conversion device comprises a substrate having a first surface, a rotating device for rotating the substrate, a wavelength conversion element disposed on the first surface side of the substrate and converting incident first light having a first wavelength band into second light having a second wavelength band different from the first wavelength band, and a phase change medium to which heat from the wavelength conversion element is transferred. The substrate has a recess provided on the first surface side of the substrate at a position corresponding to the wavelength conversion element, the phase change medium is sealed in the recess, and the phase state of the phase change medium is a two-phase state of liquid phase and solid phase, at least while the first light is incident on the wavelength conversion element.

Description

Technical Field

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

Background Art

[0002] Conventionally, a wavelength conversion device that converts the wavelength of incident light and emits the converted light is known (see, for example, Patent Documents 1 and 2). The wavelength conversion device described in Patent Document 1 is a phosphor wheel device including a phosphor wheel, a motor, and a fan member. The phosphor wheel rotated by the motor has a disk-shaped substrate and a phosphor disposed along the circumferential direction of the substrate on one surface of the substrate. The fan member is a stainless steel sheet metal attached to the other surface of the substrate and has a plurality of blades. The plurality of blades are formed by bending the stainless steel sheet metal. When the phosphor wheel rotates, an air flow is generated by the plurality of blades, and the generated air flow cools the phosphor excited by the incident excitation light and heated, and the substrate to which the heat of the phosphor is transferred.

[0003] The wavelength conversion device described in Patent Document 2 is a fluorescence generation device including a fluorescent film, a disk-shaped vapor chamber filled with a working fluid therein, and a stepping motor. The vapor chamber is rotatable by a motor, and a fluorescent film is formed in an annular shape on one surface of the vapor chamber. When laser light is incident on the fluorescent film and the fluorescent film generates heat, the vapor chamber transfers the heat transmitted from the fluorescent film to the working fluid and transfers it to the other surface of the vapor chamber, and radiates heat from a heat radiating portion located on the other surface. Further, due to the rotation of the vapor chamber, both capillary force and centrifugal force act on the working fluid condensed at the heat radiating portion of the vapor chamber. Therefore, the condensed working fluid can be easily moved to the inner surface of the vapor chamber corresponding to the fluorescent film provided on the peripheral side of the vapor chamber, improving the heat transport efficiency.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-066061 [Patent Document 2] Japanese Patent Publication No. 2017-207673 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In the wavelength conversion device described in Patent Document 1, the phosphor and substrate are cooled by the airflow generated by a fan member that rotates together with the substrate. However, since the phosphor and substrate are cooled only by airflow, there is a possibility that the cooling of the phosphor and substrate will be insufficient. This leads to the problem that the light utilization efficiency of the phosphor tends to decrease. While the wavelength conversion device described in Patent Document 2 can rapidly diffuse and transfer heat from the fluorescent film using a vapor chamber, it has the problem that it is difficult to maintain the temperature of the fluorescent film in a temperature range that is sufficiently high for the optical utilization efficiency of the fluorescent film. Therefore, there has been a demand for a configuration that can easily maintain the temperature of the phosphor. [Means for solving the problem]

[0006] A wavelength conversion device according to a first aspect of the present disclosure comprises a substrate having a first surface, a rotating device for rotating the substrate, a wavelength conversion element disposed on the first surface side of the substrate and converting incident first light having a first wavelength band into second light having a second wavelength band different from the first wavelength band, and a phase change medium on which heat from the wavelength conversion element is transferred, wherein the substrate has a recess provided on the first surface side of the substrate at a position corresponding to the wavelength conversion element, the phase change medium is sealed in the recess, and the phase state of the phase change medium is a two-phase state of liquid and solid phase at least while the first light is incident on the wavelength conversion element.

[0007] A light source device according to a second aspect of this disclosure comprises a light source that emits the first light, and a wavelength conversion device according to the first aspect, to which the first light emitted from the light source is incident.

[0008] A projector according to a third aspect of this disclosure comprises a light source device according to the second aspect, an optical modulator for modulating light emitted from the light source device, and a projection optical device for projecting the light modulated by the optical modulator. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram showing the configuration of the projector in the first embodiment. [Figure 2] A schematic diagram showing the configuration of the light source device in the first embodiment. [Figure 3] A perspective view showing the wavelength conversion device in the first embodiment. [Figure 4] A perspective view showing the wavelength conversion device in the first embodiment. [Figure 5] An exploded perspective view showing the wavelength conversion device in the first embodiment. [Figure 6] A front view showing the wavelength conversion device in the first embodiment. [Figure 7] A cross-sectional view showing a phosphor wheel in the first embodiment. [Figure 8] A plan view showing an enlarged view of the recess in the first embodiment. [Figure 9] A perspective view showing a wavelength conversion device included in the light source device of a projector in the second embodiment. [Figure 10] A perspective view showing the wavelength conversion device in the second embodiment. [Figure 11] An exploded perspective view showing the wavelength conversion device in the second embodiment. [Figure 12] An exploded perspective view showing the wavelength conversion device in the second embodiment. [Figure 13] A cross-sectional view showing a phosphor wheel in the second embodiment. [Figure 14]Perspective view showing the wavelength conversion device included in the light source device of the projector in the third embodiment. [Figure 15] Cross-sectional view showing the phosphor wheel in the third embodiment. [Figure 16] Plan view showing the wavelength conversion device included in the light source device of the projector in the fourth embodiment. [Figure 17] Diagram showing the positional relationship between the concave portion and the wavelength conversion element in the fourth embodiment. [Embodiments for Carrying Out the Invention]

[0010] [First Embodiment] Hereinafter, the first embodiment of the present disclosure will be described based on the drawings. [Schematic Configuration of Projector] FIG. 1 is a schematic diagram showing the configuration of a projector 1 according to this embodiment. The projector 1 according to this embodiment projects image light according to image information. As shown in FIG. 1, the projector 1 includes an exterior housing 11 and an image projection device 2 housed in the exterior housing 11. In addition, although not shown, the projector 1 includes a control device that controls the operation of the projector 1, a power supply device that supplies power to the electronic components of the projector 1, and a cooling device that cools the cooling target of the projector 1.

[0011] [Configuration of Image Projection Device] The image projection device 2 forms image light according to the input image information and projects the formed image light. The image projection device 2 includes a light source device 3, a homogenizing optical system 21, a color separation optical system 22, a relay optical system 23, an image forming device 24, an optical component housing 25, and a projection optical device 26.

[0012] The light source device 3 emits illumination light to the homogenizing optical system 21. The configuration of the light source device 3 will be described in detail later. The homogenization optical system 21 homogenizes the illumination light emitted from the light source device 3. The homogenized illumination light passes through the color separation optical system 22 and the relay optical system 23 to illuminate the modulation region of the light modulation device 243, which will be described later. The homogenization optical system 21 includes two lens arrays 211 and 212, a polarization conversion element 213, and a superimposed lens 214. The color separation optical system 22 separates the illumination light incident from the homogenization optical system 21 into red, green, and blue light. The color separation optical system 22 includes two dichroic mirrors 221 and 222, and a reflective mirror 223 that reflects the blue light separated by the dichroic mirror 221.

[0013] The relay optical system 23 is located in the optical path of red light, which is longer than the optical paths of other colored light, in order to suppress the loss of red light. The relay optical system 23 includes an incident lens 231, a relay lens 233, and reflective mirrors 232 and 234. In this embodiment, red light is directed to the relay optical system 23. However, this is not the only option; for example, the colored light with a longer optical path than the other colored light may be designated as blue light, and the blue light may be directed to the relay optical system 23.

[0014] The image forming apparatus 24 modulates the incident red, green, and blue light, and combines the modulated light to form an image. The image forming apparatus 24 includes three field lenses 241 provided according to the incident color light, three incident polarizers 242, three light modulators 243, three exit polarizers 244, and one color synthesis optical system 245.

[0015] The optical modulator 243 modulates the light from the light source 3 to form image light. Specifically, the optical modulator 243 modulates the color light incident from the incident polarizer 242 according to the image signal and emits the modulated color light. The three optical modulators 243 include an optical modulator 243R that modulates red light, an optical modulator 243G that modulates green light, and an optical modulator 243B that modulates blue light. A transmissive liquid crystal panel can be exemplified as an optical modulator 243.

[0016] The color synthesis optical system 245 synthesizes three colored lights modulated by the light modulators 243R, 243G, and 243B. The image light synthesized by the color synthesis optical system 245 is incident on the projection optical device 26. In this embodiment, the color synthesis optical system 245 is composed of a substantially rectangular cross dichroic prism, but it may be composed of a plurality of dichroic mirrors.

[0017] The optical component housing 25 houses the homogenization optical system 21, the color separation optical system 22, the relay optical system 23, and the image forming apparatus 24 described above. The image projection apparatus 2 has a design optical axis Ax1, and the optical component housing 25 holds the homogenization optical system 21, the color separation optical system 22, the relay optical system 23, and the image forming apparatus 24 at predetermined positions along the optical axis Ax1. The light source device 3 and the projection optical device 26 are positioned at predetermined positions along the optical axis Ax1. The projection optical device 26 projects image light incident from the image forming apparatus 24 onto a projection surface such as a screen. In other words, the projection optical device 26 projects the image light formed by the image forming apparatus 24. The projection optical device 26 can be, for example, a lens assembly comprising a plurality of lenses (not shown) and a lens barrel 261 that houses the plurality of lenses.

[0018] [Configuration of the light source device] Figure 2 is a schematic diagram showing the light source device 3. The light source device 3 emits illumination light to the image forming apparatus 24 into the uniformization optical system 21. As shown in Figure 2, the light source device 3 comprises a light source housing 31, a light source 32, an afocal optical element 33, a first phase difference element 34, a diffuse transmission element 35, a light separation and synthesis element 36, a first light focusing element 37, a second phase difference element 38, a second light focusing element 39, a diffuse optical element 40, a third phase difference element 41, and a wavelength conversion device 5A.

[0019] The light source device 3 has an optical axis Ax2 that extends in a straight line, and an optical axis Ax3 that is perpendicular to optical axis Ax2 and extends in a straight line. Optical axis Ax3 coincides with optical axis Ax1 in the homogenization optical system 21. The light source 32, afocal optical element 33, first phase difference element 34, diffuse transmission element 35, light separation and synthesis element 36, second phase difference element 38, second light concentrating element 39, and diffuse optical element 40 are arranged on the optical axis Ax2. The wavelength conversion device 5A, the first light concentrator 37, the light separation and synthesis element 36, and the third phase difference element 41 are arranged on the optical axis Ax3. In the following description, the three mutually orthogonal directions are referred to as the +X direction, the +Y direction, and the +Z direction. In this embodiment, the +X direction is the direction in which the light source 32 emits light along the optical axis Ax2, and the +Z direction is the direction in which the light source device 3 emits illumination light along the optical axis Ax3. Although not shown in the illustration, the direction opposite to the +X direction is referred to as the -X direction, the direction opposite to the +Y direction is referred to as the -Y direction, and the direction opposite to the +Z direction is referred to as the -Z direction.

[0020] [Configuration of the light source enclosure] The light source housing 31 houses the light source 32, afocal optical element 33, first phase difference element 34, diffuse transmission element 35, light separation and synthesis element 36, first light focusing element 37, second phase difference element 38, second light focusing element 39, diffuse optical element 40, third phase difference element 41, and wavelength conversion device 5A. The light source housing 31 is a sealed housing that makes it difficult for dust and other particles to enter the interior.

[0021] [Light source configuration] The light source 32 comprises at least one solid-state light-emitting element 321, which emits light incident on the diffusion optical element 40 and the wavelength conversion device 5A in the +X direction. The solid-state light-emitting element 321 emits blue light, which is the excitation light. For example, the solid-state light-emitting element 321 is a laser diode (LD) that emits laser light with a peak wavelength of 440 nm. The light emitted by the light source 32 is s-polarized blue light BLs directed to the light separation and synthesis element 36. However, the light emitted by the light source 32 may also be p-polarized blue light BLp directed to the light separation and synthesis element 36, or it may be blue light containing a mixture of s-polarized and p-polarized light. In the latter case, the first phase difference element 34 can be omitted.

[0022] [Configuration of afocal optical elements] The afocal optical element 33 adjusts the beam diameter of blue light BLs incident from the light source 32 in the +X direction. The afocal optical element 33 consists of a lens 331 that focuses the incident light and a lens 332 that parallelizes the light beam focused by the lens 331. Note that the afocal optical element 33 is optional.

[0023] [Configuration of the first phase difference element] The first phase difference element 34 is provided between lens 331 and lens 332. The first phase difference element 34 converts a portion of the incident blue light BLs into blue light BLp, and emits light containing both s-polarized blue light BLs and p-polarized blue light BLp. The first phase difference element 34 may be rotated by a rotating device around a rotation axis along the optical axis Ax2. In this case, the ratio of s-polarized and p-polarized components in the blue light emitted from the first phase difference element 34 can be adjusted according to the rotation angle of the first phase difference element 34.

[0024] [Configuration of the diffuse transmission element] The diffuse transmission element 35 equalizes the illuminance distribution of blue light BLp and BLs incident from lens 332 in the +X direction. The blue light BLs and BLp that have passed through the diffuse transmission element 35 are then incident on the light separation and synthesis element 36. The diffuse transmission element 35 can be exemplified by a configuration having a hologram, a configuration in which a plurality of small lenses are arranged in a plane perpendicular to the optical axis, and a configuration in which the surface through which light passes is rough. Alternatively, a homogenizer optical element having a pair of multi-lenses may be used instead of the diffuse transmission element 35.

[0025] [Configuration of the photo-separating and synthesizing element] The light separation and synthesis element 36 has the function of a light separation element that separates incident light, and the function of a photosynthesis element that synthesizes light incident from two directions. The light separation and synthesis element 36 is a polarizing beam splitter that separates the s-polarized and p-polarized components contained in the incident light. Specifically, the light separation and synthesis element 36 reflects the s-polarized component and transmits the p-polarized component. Furthermore, the light separation and synthesis element 36 has a color separation characteristic that transmits light of a predetermined wavelength or greater, regardless of whether it is the s-polarized or p-polarized component. Therefore, of the blue light BLp and BLs incident from the diffusion transmission element 35 to the light separation and synthesis element 36, the p-polarized blue light BLp is transmitted through the light separation and synthesis element 36 in the +X direction and incident on the second phase difference element 38. On the other hand, the s-polarized blue light BLs is reflected in the -Z direction by the light separation and synthesis element 36 and incident on the first light concentrating element 37. The light separation and synthesis element 36 may also have the function of a half-mirror that allows some of the light incident from the light source 32 via the diffusion transmission element 35 to pass through and reflects the remaining light, and the function of a dichroic mirror that reflects the blue light incident from the diffusion optical element 40 and transmits the fluorescence incident from the wavelength conversion device 5A that has a wavelength longer than the wavelength of blue light. In this case, the first phase difference element 34 can be omitted.

[0026] [Configuration of the first light-gathering element] The first light-gathering element 37 constitutes the pickup optical system. The first light-gathering element 37 focuses the blue light BLs reflected in the -Z direction by the light separation and synthesis element 36 onto the wavelength conversion element 54 of the phosphor wheel 52A, which is part of the wavelength conversion device 5A (described later). The first light-gathering element 37 also parallelizes the fluorescent YL incident from the wavelength conversion element 54 in the +Z direction and emits the parallelized fluorescent YL to the light separation and synthesis element 36. In this embodiment, the first light-gathering element 37 is composed of three lenses 371, 372, and 373, but the number of lenses constituting the first light-gathering element 37 is not limited.

[0027] [Outline configuration of the wavelength conversion device] The wavelength conversion device 5A includes a phosphor wheel 52A that converts the wavelength of the blue light BLs incident from the first light-gathering element 37 and emits fluorescent YL. The phosphor wheel 52A is a so-called reflective wavelength conversion element and emits fluorescent YL in the direction opposite to the incident direction of the excitation light, the blue light BLs. The configuration of the wavelength conversion device 5A will be described in detail later.

[0028] The fluorescent yellow light (YL) emitted from the wavelength converter 5A in the +Z direction is parallelized by the first light-gathering element 37 and then incident on the light separation and synthesis element 36. As described above, since the light separation and synthesis element 36 has the characteristic of transmitting fluorescent yellow light (YL), the fluorescent yellow light incident on the light separation and synthesis element 36 along the +Z direction passes through the light separation and synthesis element 36 and is incident on the third phase difference element 41.

[0029] [Configuration of the second phase difference element] The second phase difference element 38 is positioned in the +X direction relative to the light separation and synthesis element 36. That is, the second phase difference element 38 is positioned between the light separation and synthesis element 36 and the second light concentrator element 39. The second phase difference element 38 converts the blue light BLp that has passed through the light separation and synthesis element 36 in the +X direction into circularly polarized blue light BLc. The blue light BLc that has passed through the second phase difference element 38 in the +X direction is incident on the second light concentrator element 39.

[0030] [Configuration of the second light-gathering element] The second light-gathering element 39 focuses the blue light BLc that passes through the light separation and synthesis element 36 in the +X direction and is incident from the second phase difference element 38 onto the diffuse optical element 40. The second light-gathering element 39 also parallelizes the light incident from the diffuse optical element 40 in the -X direction and emits it to the second phase difference element 38. In this embodiment, the second light-gathering element 39 is composed of three lenses 391, 392, and 393, but the number of lenses constituting the second light-gathering element 39 is not limited.

[0031] [Configuration of Diffuse Optical Elements] The diffusing optical element 40 diffuses the incident blue light BLc at a diffusion angle similar to that of the fluorescent YL emitted from the wavelength conversion device 5A. Specifically, the diffusing optical element 40 reflects and diffuses the blue light BLc incident from the second light-gathering element 39 in the +X direction in the -X direction. The diffusing optical element 40 is a reflective element that performs Lambertian reflection on the incident blue light BLc. The diffusing optical element 40 may be rotated by a rotation device around a rotation axis parallel to the optical axis Ax2. The blue light BLc diffused by the diffusing optical element 40 passes through the second focusing element 39 and then enters the second phase difference element 38. When the blue light BLc that enters the diffusing optical element 40 is reflected by the diffusing optical element 40, it is converted into circularly polarized light with the opposite direction of rotation. Therefore, the blue light BLc that enters the second phase difference element 38 via the second focusing element 39 is converted into s-polarized blue light BLs by the second phase difference element 38. Then, the blue light BLs is reflected in the +Z direction by the light separation and synthesis element 36 and enters the third phase difference element 41. That is, the light that enters the third phase difference element 41 from the light separation and synthesis element 36 is white light containing a mixture of blue light BLs and fluorescent YL.

[0032] [Configuration of the third phase difference element] The third phase difference element 41 is provided in the output port 311 located on the surface of the light source housing 31 facing the +Z direction. The third phase difference element 41 converts the blue light BLs and white light including fluorescence YL incident from the light separation and synthesis element 36 into white light containing a mixture of s-polarized and p-polarized light. This converted white light is emitted in the +Z direction as illumination light LT through the output port 311 and incident on the homogenization optical system 21 described above.

[0033] [Configuration of the wavelength conversion device] Figures 3 and 4 are perspective views of the wavelength converter 5A. More specifically, Figure 3 is a perspective view of the wavelength converter 5A as seen from the side where the excitation light is incident, and Figure 4 is a perspective view of the wavelength converter 5A as seen from the opposite side of the side where the excitation light is incident. Furthermore, Figure 5 is an exploded perspective view of the wavelength converter 5A as seen from the side where the excitation light is incident, and Figure 6 is a front view of the wavelength converter 5A as seen from the side where the excitation light is incident. The wavelength conversion device 5A converts the first light having a first wavelength band into the second light having a second wavelength band different from the first wavelength band. Specifically, the wavelength conversion device 5A converts the wavelength of the blue light BLs, which is the excitation light emitted from the light source 32, to emit the fluorescent YL. The wavelength conversion device 5A includes a rotating device 51 shown in Figures 3 to 5 and a phosphor wheel 52A shown in Figures 3 to 6. In the following explanation, the -Z direction is the direction in which the excitation light is incident on the wavelength converter 5A. The +Z direction is the side of the wavelength converter 5A where the excitation light is incident, and the -Z direction is the side of the wavelength converter 5A opposite to the side where the excitation light is incident.

[0034] [Configuration of the rotating device] The rotating device 51 rotates the phosphor wheel 52A around the rotation axis Rx. The rotating device 51 is a motor, and the base material 53 of the phosphor wheel 52A is fixed to the rotating device 51 by a screw SC. In other words, the rotating device 51 holds the base material 53 and rotates the base material 53 around the rotation axis Rx. The rotating device 51 comprises a rotating device body 511 and a rotor 512. The rotating device body 511 rotates the rotor 512 around the rotation axis Rx. The rotor 512 is connected to the base material 53 by a screw SC. A portion of the rotor 512 is inserted into an opening 531 provided in the base material 53.

[0035] [Phosphor Wheel Configuration] The phosphor wheel 52A is rotated by a rotating device 51 and emits blue light BLs, which is first light having a first wavelength band, as second light YL, which is second light having a second wavelength band. The phosphor wheel 52A comprises a substrate 53, a wavelength conversion element 54, a phase change medium 55, a metal layer 56, and an adhesive layer 57.

[0036] [Composition of the base material] The base material 53 is an aluminum disc that is rotated by a rotating device 51. The base material 53 has a first surface 53A facing the +Z direction, a second surface 53B located on the opposite side of the first surface 53A and facing the -Z direction, an opening 531, a plurality of fins 532, and a recess 533 as shown in Figures 5 and 6.

[0037] As shown in Figure 3, the opening 531 is formed in a circular shape in the center of the base material 53 when viewed along the rotation axis Rx, and penetrates the base material 53 along the rotation axis Rx. A portion of the rotor 512 is inserted into the opening 531 from the -Z direction. Multiple fins 532 are provided around the opening 531. The multiple fins 532 are arranged at equal intervals along the circumferential direction centered on the rotation axis Rx. Each of the multiple fins 532 is formed by cutting and bending the base material 53 in the -Z direction. When the base material 53 is rotated by the rotating device 51, the multiple fins 532 generate an airflow that cools the phosphor wheel 52A and also dissipate heat from the wavelength conversion element 54 that is transmitted to the base material 53.

[0038] As shown in Figures 5 and 6, the recess 533 is provided radially outward of the base material 53 relative to the plurality of fins 532. The recess 533 is formed in a ring shape centered on the rotation axis Rx when viewed along the rotation axis Rx, and is recessed in the -Z direction. A metal layer 56 is provided on the surface of the recess 533, and a phase change medium 55 is placed inside the recess 533. The recess 533 is closed by a wavelength conversion element 54. The shape of the outer edge of the recess 533 will be described in detail later.

[0039] [Configuration of the wavelength conversion element] The wavelength conversion element 54 is formed in a ring shape centered on the rotation axis Rx and is positioned on the first surface 53A side of the base material 53. In this embodiment, the wavelength conversion element 54 is positioned in the +Z direction relative to the base material 53 and is fixed to the first surface 53A so as to close the recess 533. Therefore, the dimensions of the wavelength conversion element 54 in the radial direction centered on the rotation axis Rx are larger than the dimensions of the recess 533 in the radial direction of the base material 53. The wavelength conversion element 54 contains a phosphor that converts the first light, blue light BLs, into the second light, fluorescent YL. An example of such a phosphor is a YAG phosphor containing Ce as an activator.

[0040] [Composition of the phase change medium] As shown in Figures 5 and 6, the phase change medium 55 is sealed within the recess 533 by the wavelength conversion element 54. At least a portion of the phase change medium 55 changes from a solid state to a liquid state due to the heat transmitted from the wavelength conversion element 54. That is, the phase state of at least a portion of the phase change medium 55 changes from a solid phase to a liquid phase due to the heat from the wavelength conversion element 54. Thus, the phase change medium 55 has the characteristic of being in a two-phase state of liquid and solid phases, at least while blue light BLs is incident on the wavelength conversion element 54, and as long as it is in this two-phase state, the temperature of the phase change medium 55 remains approximately constant even if further heat is transmitted. In this embodiment, the phase change medium 55 is a liquid metal having a metallic luster. As the liquid metal, for example, a low-melting-point metal such as Ga with a melting point of 29.8°C, In with a melting point of 156.4°C, and Sn with a melting point of 231.9°C, or an alloy containing multiple low-melting-point metals can be used. When the liquid metal used as the phase change medium 55 is an alloy containing multiple low-melting-point metals, the melting and boiling points of the liquid metal can be adjusted by the composition and blending of the low-melting-point metals, and the temperature range in which the two-phase state is maintained can be adjusted. In this way, by adjusting the blending and ratio of the low-melting-point metals, a phase change medium 55 can be prepared in which a two-phase state of liquid and solid phases is maintained at least while blue light BLs is incident on the wavelength conversion element 54. That is, a phase change medium 55 can be prepared in which the temperature remains substantially constant even when heat is transferred from the wavelength conversion element 54 while blue light BLs is incident on the wavelength conversion element 54.

[0041] The phase change medium 55 in this embodiment satisfies the following formula 1. In Equation 1, Q is the amount of blue light BLs incident on the wavelength conversion element 54 per unit time (W), and η is the conversion efficiency of the wavelength conversion element 54 from blue light BLs to fluorescent YL. The conversion efficiency is, for example, the amount of light emitted by the fluorescent YL divided by the amount of light incident on the blue light BLs. In Equation 1, ΔH is the heat of fusion (J / g) of the phase change medium 55, ρ is the specific gravity of the phase change medium 55, and t is the depth (mm) of the recess 533. Note that specific gravity is the density (g / mm³). 3 ) is also acceptable. In Equation 1, n is the rotational speed (rpm) of the substrate 53 by the rotating device 51, d is the spot diameter (mm) of the blue light BLs incident on the wavelength conversion element 54, and D is the distance (mm) between the center of the spot of the blue light BLs irradiated on the wavelength conversion element 54 and the rotation axis Rx of the substrate 53. In Equation 1, π is the ratio of a circle's circumference to its diameter (pi). The right-hand side of Equation 1 represents the heat of melting required per unit time.

[0042]

number

[0043] By satisfying equation 1 above, it is possible to suppress the complete dissolution of the liquid metal in the region corresponding to the spot of blue light BLs in the phase change medium 55 at the moment the phosphor wheel 52A rotates and blue light BLs are spot-irradiated. At this time, the phase state of the liquid metal in that region is a two-phase state consisting of a solid phase and a liquid phase. Here, during the period until the phase change from solid to liquid phase is completed, heat is used for the change in phase state, so the temperature of the phase change medium 55 during this period remains constant at the melting point of the liquid metal and does not rise. Therefore, by re-solidifying the molten liquid metal through cooling caused by the rotation of the phosphor wheel 52A between the time the phosphor wheel 52A completes one rotation and the same region of the wavelength conversion element 54 is spot-irradiated again, the liquid metal repeatedly melts and solidifies, making it possible to control the temperature of the wavelength conversion element 54 to any temperature based on the melting point of the liquid metal. The phosphor contained in the wavelength conversion element 54 has a higher conversion efficiency to fluorescent YL when the temperature of the wavelength conversion element 54 is low, and the conversion efficiency decreases significantly when the temperature exceeds a predetermined temperature. For this reason, satisfying equation 1 above, which allows the temperature of the wavelength conversion element 54 to be controlled to an arbitrary temperature based on the melting point of the liquid metal when irradiated with blue light BLs, is effective in improving the conversion efficiency to fluorescent YL. In this embodiment, the liquid metal constituting the phase change medium 55 is a mixed metal composed of Ga, In, and Sn, which have different melting points. As described above, by changing the composition and blend of these metals, the melting point of the liquid metal, i.e., the melting point of the phase change medium 55, can be adjusted, and consequently, the temperature of the wavelength conversion element 54 during excitation light irradiation can be arbitrarily adjusted.

[0044] [Metal layer composition] Figure 7 shows a portion of the cross-section of the phosphor wheel 52A along its radial direction. In Figure 7, the radially outward direction of both the phosphor wheel 52A and the substrate 53 is indicated by arrow D1. The metal layer 56 is a metal layer composed of metals other than aluminum, and is a corrosion-inhibiting layer that suppresses corrosion of the substrate 53 by the phase change medium 55, which is a liquid metal. In this case, depending on the composition of the liquid metal, the liquid metal may corrode the aluminum. Therefore, the phase change medium 55 sealed in the recess 533 may corrode the substrate 53 which is made of aluminum. In contrast, as shown in Figure 7, the metal layer 56 is provided between the base material 53 and the phase change medium 55 on the first surface 53A side. That is, the metal layer 56 is provided on the inner surface of the recess 533 and on the periphery of the recess 533 on the first surface 53A. More specifically, the metal layer 56 is provided on the first inner surface that forms the outer peripheral edge 5331 of the recess 533, the second inner surface that forms the inner peripheral edge 5332 of the recess 533, the third inner surface that forms the bottom surface 5333 of the recess 533, and on the periphery of the recess 533 on the first surface 53A. Therefore, even if the phase change medium 55 is placed in the recess 533, corrosion of the recess 533 by the phase change medium 55 is suppressed. Note that the wavelength conversion element 54 that closes the recess 533 and seals in the phase change medium 55 does not contain aluminum. Therefore, even if the phase change medium 55 comes into contact with the wavelength conversion element 54, corrosion of the wavelength conversion element 54 by the phase change medium is suppressed.

[0045] [Composition of the adhesive layer] The adhesive layer 57 adheres the first surface 53A to the wavelength conversion element 54. The adhesive layer 57 is provided on the periphery of the recess 533 when viewed from the +Z direction on the first surface 53A. In addition to adhering and fixing the wavelength conversion element 54 to the first surface 53A, the adhesive layer 57 also suppresses the leakage of the phase change medium 55, which is sealed inside the recess 533 by the wavelength conversion element 54, to the outside of the recess 533.

[0046] [Construction of the outer edge of the recess] Figure 8 is a plan view showing an enlarged view of the recess 533 as seen from the +Z direction. As shown in Figure 8, a plurality of protrusions 534 are formed on the outer periphery of the recess 533, arranged along the circumferential direction with respect to the rotation axis Rx. In other words, the base material 53 has a plurality of protrusions 534 that communicate with the recess 533. Each of the multiple protrusions 534 is a portion that extends radially outward from the outer edge of the recess 533, centered on the rotation axis Rx of the base material 53. Each of the multiple protrusions 534 has multiple inclined surfaces 5341, 5342 that, when viewed along the rotation axis Rx, intersect a straight line that passes through the rotation axis Rx and the protrusion 534 and is along the radial direction of the base material 53, and whose extension line is inclined with respect to the tangent line at the intersection of the straight line and the outer edge of the base material 53. That is, each of the inclined surfaces 5341, 5342 intersects the base material 53 at a different angle with respect to the radial direction, and the inclined surfaces 5341 and 5342 face each other and intersect each other. For example, if one of the multiple protrusions 534 is designated as protrusion 534A, the extension line EL1 of the inclined surface 5341 of protrusion 534A passes through protrusion 534A and intersects with a straight line L1 that runs along the radial direction of the base material 53, and also intersects with a tangent line L2 at the intersection of the straight line L1 and the outer edge of the base material 53. Similarly, the extension line EL2 of the inclined surface 5342 intersects with both the straight line L1 and the tangent line L2. In protrusion 534A, the inclined surfaces 5341 and 5342 intersect the base material 53 at different angles with respect to the radial direction, and the inclined surfaces 5341 and 5342 face each other and intersect each other.

[0047] Such protrusions 534 have the function of promoting convection within the recesses 533 of the phase change medium 55, which has changed its phase state from solid to liquid due to the heat transmitted from the wavelength conversion element 54. Note that the liquid phase change medium 55 refers to the phase change medium 55 in a liquid state. More specifically, because the liquid phase change medium 55 is fluid, it flows radially outward from the base material 53 due to the centrifugal force acting on the base material 53 when it rotates. After this, the liquid phase change medium 55 flows along the inclined surfaces 5341 and 5342 and returns to the radially inward side of the base material 53. That is, the liquid phase change medium 55 convects within the recess 533 including the convex portion 534, as shown by the arrow AR in Figure 8. This makes it possible to equalize the temperature of the phase change medium and makes it easier to maintain a nearly constant temperature for the two-phase phase change medium. In addition, by causing the phase change medium 55 to flow, the liquid phase change medium 55 can come into contact with the base material 53, which is being rotated and cooled, and the re-solidification of the liquid phase change medium 55 can be promoted. In addition, the flow of the phase change medium 55 within the recess 533 prevents the concentration of the liquid phase change medium 55 at the outer edge of the recess 533 due to centrifugal force. Therefore, leakage of the phase change medium 55 to the outside of the recess 533 can be prevented.

[0048] [Depth of the recess] As shown in Figure 7, the depth of the recess 533 varies depending on its position within the recess 533. The depth of the recess 533 is the dimension between the first surface 53A and the bottom surface 5333 of the recess 533. More specifically, the depth of the outer peripheral edge portion of the recess 533 is smaller than the depth of the inner peripheral edge portion of the recess 533. In this embodiment, the depth of the recess 533 decreases from the inner peripheral edge to the outer peripheral edge. This configuration further promotes convection of the liquid phase change medium when the substrate 53 is rotated.

[0049] [Effects of Phase Change Media] In this embodiment, the phase change medium 55 can be in contact with the wavelength conversion element 54 on the side opposite to the side into which the first light, blue light BLs, is incident. A portion of the solid phase change medium 55 melts due to the heat transmitted from the wavelength conversion element 54, and as a result, the phase state of the phase change medium 55 becomes a two-phase state of solid and liquid phases. As described above, the temperature of the two-phase phase change medium 55 remains approximately constant as long as the two-phase state is not resolved. That is, in the mixed state of the solid phase change medium 55 and the liquid phase change medium 55, the temperature of the phase change medium 55 remains approximately constant even if further heat is transmitted to the phase change medium 55. For this reason, the temperature of the wavelength conversion element 54 in contact with the phase change medium 55 can be maintained within a predetermined temperature range. As described above, the temperature of the phase change medium 55 when it is in a two-phase state can be defined by the composition and formulation of the phase change medium 55, and therefore the temperature range of the wavelength conversion element 54 when blue light BLs are incident on it can be defined. For this reason, by adjusting the composition and formulation of the phase change medium 55 so that the temperature range of the wavelength conversion element 54 is such that the utilization efficiency of blue light BLs by the wavelength conversion element 54 is sufficiently high, the temperature of the wavelength conversion element 54 can be maintained at a temperature in which the wavelength conversion element 54 can maintain high light utilization efficiency.

[0050] Furthermore, since the phase change medium 55 is a liquid metal with metallic luster, it reflects light incident from the wavelength conversion element 54. Therefore, the light incident from the wavelength conversion element 54 to the phase change medium 55 can be returned to the wavelength conversion element 54 by the phase change medium 55. As a result, when blue light BLs is incident on the phase change medium 55, the blue light BLs reflected by the phase change medium 55 can be converted into fluorescent YL by the wavelength conversion element 54. When fluorescent YL is incident on the phase change medium 55, the fluorescent YL reflected by the phase change medium 55 can be emitted to the outside from the wavelength conversion element 54. Therefore, the utilization efficiency of blue light BLs by the wavelength conversion element 54 can be increased, and the diffusion of fluorescent YL emitted from the wavelength conversion element 54 can be suppressed.

[0051] [Effects of the First Embodiment] The projector 1 according to this embodiment, as described above, provides the following effects. The projector 1 comprises a light source device 3, a light modulator 243 that modulates the light emitted from the light source device 3, and a projection optical device 26 that projects the light modulated by the light modulator 243. The light source device 3 includes a light source 32 that emits blue light BLs as first light, and a wavelength conversion device 5A into which the blue light BLs emitted from the light source 32 are incident.

[0052] The wavelength conversion device 5A comprises a rotating device 51, a base material 53, a wavelength conversion element 54, and a phase change medium 55. The base material 53 has a first surface 53A, and the rotating device 51 rotates the base material 53. The wavelength conversion element 54 is positioned on the first surface 53A side of the substrate 53. That is, the wavelength conversion element 54 is positioned on the side of the substrate 53 where the blue light BLs are incident. The wavelength conversion element 54 converts the incident blue light BLs into fluorescent YL. The blue light BLs corresponds to first light having a first wavelength band, and the fluorescent YL corresponds to second light having a second wavelength band different from the first wavelength band. Heat from the wavelength conversion element 54 is transferred to the phase change medium 55. The substrate 53 has a recess 533 provided on the first surface 53A side of the substrate 53 at a position corresponding to the wavelength conversion element 54. The phase change medium 55 is sealed in the recess 533, and the phase state of the phase change medium 55 is a two-phase state of liquid and solid phase, at least while blue light BLs is incident on the wavelength conversion element 54.

[0053] Here, the temperature of the phase change medium 55 remains constant while the above two-phase state is maintained. Therefore, as long as blue light BLs is incident on the wavelength conversion element 54, the temperature of the phase change medium 55 remains approximately constant, and the temperature of the wavelength conversion element 54 can be maintained within a predetermined range. From this, by adjusting the composition and formulation of the phase change medium 55 to adjust the temperature range in which the two-phase state of the phase change medium 55 is maintained, the temperature of the wavelength conversion element 54 can be maintained within a temperature range in which the optical utilization efficiency of the wavelength conversion element 54 is sufficiently high. Accordingly, the optical utilization efficiency of the wavelength conversion element 54 can be improved. In addition, because the recess 533 in which the phase change medium 55 is enclosed is provided at the above position, it is possible to easily transfer heat from the wavelength conversion element 54 to the phase change medium 55. Furthermore, since the light source device 3 is equipped with a wavelength converter 5A, a light source device 3 can be configured that is highly bright and has high conversion efficiency from blue light BLs to fluorescence YL, and consequently, a projector 1 capable of projecting high-brightness images can be configured.

[0054] In the wavelength conversion device 5A, the phase change medium 55 is a liquid metal. The liquid metal reflects the fluorescent YL converted by the wavelength conversion element 54 in the +Z direction. The -Z direction corresponds to the incident direction of the blue light BLs incident on the wavelength conversion element 54, and the +Z direction corresponds to the opposite direction to the -Z direction. With this configuration, the phase change medium 55, which is a liquid metal, can be used as a reflective layer. Therefore, the configuration of the wavelength conversion device 5A can be simplified compared to the case where a separate reflective layer is provided.

[0055] In the wavelength conversion device 5A, the base material 53 is made of aluminum. The base material 53 has a metal layer 56 made of a metal other than aluminum, which is placed between the base material 53 and the phase change medium 55 on the first surface 53A side. In this embodiment, the metal layer 56 is provided on the first surface 53A, including the inside of the recess 533. The metal layer 56 corresponds to a corrosion suppression layer. In this case, if the phase change medium 55 is a liquid metal, depending on the type of liquid metal, the phase change medium 55 may corrode the aluminum, which could lead to corrosion of the base material 53. In contrast, with the above configuration, the metal layer 56, which is made of a metal other than aluminum, can suppress corrosion of the substrate 53 by the phase change medium 55. Therefore, the wavelength conversion device 5A can be used stably.

[0056] In the wavelength conversion device 5A, the recess 533 has a plurality of protrusions 534 that extend radially outward from the base material 53. The plurality of protrusions 534 are provided on the outer peripheral edge 5331 located radially outward from the base material 53 in the recess 533. Here, when the substrate 53 rotates, centrifugal force acts on the phase change medium 55 sealed in the recess 533, causing the liquid phase change medium 55 to flow into the multiple protrusions 534 provided on the outer peripheral edge 5331 of the recess 533. This makes it easier to convect the liquid phase change medium 55 within the recess 533, thus making it easier to equalize the temperature of the entire phase change medium 55 to which heat is transferred, and thus maintaining the temperature of the phase change medium 55, and consequently the temperature of the wavelength conversion element 54, at a nearly constant level. Furthermore, by causing the phase change medium 55 to flow, the liquid phase change medium 55 can come into contact with the substrate 53, which is being rotated and cooled, thus promoting the re-solidification of the liquid phase change medium 55.

[0057] In the wavelength conversion device 5A, each of the multiple protrusions 534 has multiple inclined surfaces 5341, 5342 that intersect the radial direction of the base material 53 at different angles when viewed along the rotation axis Rx of the base material 53. With this configuration, the direction of movement of the liquid phase change medium 55, which moves due to the centrifugal force acting on it when the base material 53 rotates, can be changed to a direction along the inclined surfaces 5341 and 5342. This promotes convection of the liquid phase change medium 55 within the recess 533, and also prevents the liquid phase change medium 55 from concentrating at the outer peripheral edge 5331 of the recess 533 and leaking out of the recess 533.

[0058] In the wavelength conversion device 5A, as shown in Figure 7, the depth of the radially outer portion of the substrate 53 in the recess 533 is smaller than the depth of the radially inner portion of the substrate 53 in the recess 533. With this configuration, the varying depths of the recesses 533 promote the flow of the liquid phase change medium 55 within the recesses 533 due to the centrifugal force acting when the substrate 53 rotates.

[0059] In the wavelength conversion device 5A, if Q is the amount of blue light BLs incident on the wavelength conversion element 54 per unit time, η is the conversion efficiency of the wavelength conversion element 54 from blue light BLs to fluorescence YL, ΔH is the heat of fusion of the phase change medium 55, ρ is the specific gravity of the phase change medium 55, t is the depth of the recess 533, d is the spot diameter of the blue light BLs incident on the wavelength conversion element 54, n is the rotation speed of the substrate 53 by the rotating device 51, and D is the distance between the center of the spot of the blue light BLs irradiated on the wavelength conversion element 54 and the rotation axis Rx of the substrate 53, then the phase change medium 55 satisfies the above-described equation 1. With this configuration, the molten phase change medium 55 is re-solidified by the cooling caused by the rotation of the substrate 53 and the wavelength conversion element 54 while the substrate 53 is rotating and the blue light BLs are spot-irradiated again onto the same region of the wavelength conversion element 54. This allows the phase change medium to repeatedly undergo melting and solidification. This makes it easier to control the temperature of the wavelength conversion element 54 to any temperature based on the melting point of the phase change medium 55.

[0060] [Second Embodiment] Next, a second embodiment of this disclosure will be described. The projector according to this embodiment has the same configuration as the projector 1 according to the first embodiment, but the configuration of the phosphor wheel constituting the wavelength conversion device is different. In the following description, parts that are the same or substantially the same as those already described are denoted by the same reference numerals and their description is omitted.

[0061] [Outline configuration of projector and light source device] Figures 9 and 10 are perspective views showing the wavelength converter 5B included in the light source device of the projector according to this embodiment. More specifically, Figure 9 is a perspective view showing the wavelength converter 5B as seen from the incident side of the blue light BLs, and Figure 10 is a perspective view showing the wavelength converter 5B as seen from the opposite side of the incident side of the blue light BLs. Figure 11 is an exploded perspective view showing the wavelength converter 5B as seen from the incident side of the blue light BLs, and Figure 12 is an exploded perspective view showing the wavelength converter 5B as seen from the opposite side of the incident side of the blue light BLs. Note that the fixing member 60 is not shown in Figures 11 and 12. The projector according to this embodiment has the same configuration and functions as the projector 1 according to the first embodiment, except that it is equipped with a wavelength converter 5B shown in Figures 9 to 12 in place of the wavelength converter 5A according to the first embodiment. That is, the light source device according to this embodiment has the same configuration and functions as the light source device 3 according to the first embodiment, except that it is equipped with a wavelength converter 5B in place of the wavelength converter 5A.

[0062] [Configuration of the wavelength conversion device] The wavelength conversion device 5B has the same configuration and functions as the wavelength conversion device 5A according to the first embodiment, except that it is equipped with a phosphor wheel 52B instead of the phosphor wheel 52A according to the first embodiment. That is, the wavelength conversion device 5B is equipped with a rotating device 51 and a phosphor wheel 52B. The phosphor wheel 52B, like the phosphor wheel 52A, is rotated around the rotation axis Rx by the rotating device 51 to convert the wavelength of blue light BLs and emit fluorescence YL. The phosphor wheel 52B has the same configuration and function as the phosphor wheel 52A, except that it further comprises a substrate 58, a reflective layer 59, and a fixing member 60. That is, the phosphor wheel 52B has a base material 53, a wavelength conversion element 54, a phase change medium 55, a metal layer 56, and an adhesive layer 57, as well as a substrate 58, a reflective layer 59, and a fixing member 60.

[0063] [Circuit board configuration] The substrate 58 is positioned on the incident side of the base material 53 to the blue light BLs, which is the first light, with the wavelength conversion element 54 in place. When combined with the base material 53, the substrate 58 encapsulates the phase change medium 55 located in the recess 533 of the base material 53. The substrate 58 is an aluminum disc, similar to the base material 53, and its diameter is approximately the same as the diameter of the base material 53. The substrate 58 has a first surface 58A facing the +Z direction, which is the incident side of the blue light BLs, and a second surface 58B facing the opposite side from the first surface 58A, as well as an opening 581. The opening 581 is positioned to correspond to the opening 531 when the substrate 58 is combined with the base material 53, and a portion of the rotor 512, which passes through the opening 531, is inserted from the -Z direction.

[0064] A wavelength conversion element 54, formed in a ring shape centered on the rotation axis Rx, is arranged on the first surface 58A using an adhesive or the like. The wavelength conversion element 54 is positioned on the first surface 58A corresponding to a recess 533 provided in a ring shape on the first surface 53A of the substrate 53 centered on the rotation axis Rx. A reflective layer 59 is provided on the first surface 58A in the portion where the wavelength conversion element 54 is arranged. The reflective layer 59 is provided between the wavelength conversion element 54 and the first surface 58A. Similar to the phase change medium 55 in the first embodiment, the reflective layer 59 reflects light incident from the wavelength conversion element 54 back towards the wavelength conversion element 54. The second surface 58B is the surface facing the first surface 53A of the base material 53. In this embodiment, as shown in Figure 12, the entire surface of the second surface 58B is provided with a metal layer 56 similar to the metal layer 56 that is a corrosion-inhibiting layer provided in the recess 533. However, the metal layer 56 is not limited to this and may be provided on the second surface 58B at a position facing the recess 533 of the base material 53. That is, the metal layer 56 may be formed in a ring shape that covers the recess 533 on the second surface 58B.

[0065] Figure 13 is a schematic diagram showing a portion of the radial cross-section of the phosphor wheel 52B. Specifically, Figure 13 is a schematic cross-section showing the end of the phosphor wheel 52B. As shown in Figures 9, 10, and 13, the fixing member 60 clamps the radially outer end 53E of the base material 53 and the radially outer end 58E of the substrate 58, thereby fixing the base material 53 and the substrate 58 together. The fixing member 60 maintains the assembled state of the base material 53 and the substrate 58, and also seals the phase change medium 55 between the base material 53 and the substrate 58. The fixing member 60 is formed in a ring shape along the outer edges of the base material 53 and the substrate 58, and covers the gap between the base material 53 and the substrate 58 on the outer side of the phosphor wheel 52B. This fixing member 60 prevents the phase change medium 55 from leaking radially outward from between the base material 53 and the substrate 58 to the phosphor wheel 52B.

[0066] [Effects of the second embodiment] The projector according to this embodiment described above provides the same effects as the projector 1 according to the first embodiment, as well as the following effects. The wavelength conversion device 5B further includes a substrate 58 positioned on the first surface 53A side of the base material 53. That is, the substrate 58 is positioned on the side of the base material 53 where the blue light BLs are incident. The substrate 58 has a first surface 58A on which the wavelength conversion element 54 is provided, and a second surface 58B facing the first surface 53A of the base material 53. With this configuration, the phase change medium 55 is sealed between the first surface 53A of the base material 53, where the recess 533 is provided, and the second surface 58B of the substrate 58, on which the wavelength conversion element 54 is provided on the first surface 58A. As a result, the wavelength conversion device 5A is constructed by combining the base material 53 and the substrate 58, which have relatively high strength, so the wavelength conversion device 5B can be manufactured more easily compared to the case where the wavelength conversion element 54, which has lower strength than the base material 53 and the substrate 58, is attached to the first surface 53A so as to cover the recess 533. Therefore, the ease of manufacturing the wavelength conversion device 5B can be improved.

[0067] The wavelength conversion device 5B further comprises a reflective layer 59 positioned between the wavelength conversion element 54 and the first surface 58A, which reflects the fluorescent YL converted by the wavelength conversion element 54. With this configuration, light incident on the reflective layer 59 from the wavelength conversion element 54 can be returned to the wavelength conversion element 54 by the reflective layer 59. As a result, when blue light BLs are incident on the reflective layer 59, the blue light BLs reflected by the reflective layer 59 can be converted into fluorescent YL by the wavelength conversion element 54. When fluorescent YL is incident on the reflective layer 59, the fluorescent YL reflected by the reflective layer 59 can be emitted to the outside from the wavelength conversion element 54. Therefore, the utilization efficiency of blue light BLs by the wavelength conversion element 54 can be increased, and the diffusion of fluorescent YL emitted from the wavelength conversion element 54 can be suppressed.

[0068] In the wavelength conversion device 5B, the substrate 58 is made of aluminum. The substrate 58 has a metal layer 56 made of a metal other than aluminum, which is provided on the second surface 58B. As described above, when the phase change medium 55 is a liquid metal, depending on the type of liquid metal, contact between the liquid metal and aluminum may cause the aluminum to corrode. Therefore, depending on the type of phase change medium 55, the base material 53 may corrode. In contrast, with the above configuration, the metal layer 56, which is made of a metal other than aluminum, can suppress corrosion of the substrate 58 by the phase change medium 55. Therefore, the wavelength conversion device 5B can be used stably.

[0069] The wavelength conversion device 5B further includes a fixing member that clamps the radially outer end 53E of the base material 53 and the radially outer end 58E of the substrate 58 to fix the base material 53 and the substrate 58. With this configuration, since the end 53E and end 58E are held between the fixing member 60, leakage of the phase change medium 55 located between the base material 53 and the substrate 58 to the outside of the base material 53 and the substrate 58 can be suppressed.

[0070] [Third Embodiment] Next, a third embodiment of this disclosure will be described. The projector according to this embodiment has the same configuration as the projector according to the second embodiment, but the configuration of the wavelength conversion device is different. More specifically, the wavelength conversion device according to this embodiment differs in that it has an extended portion and a bent portion instead of a fixed member 60. In the following description, parts that are the same or substantially the same as parts already described will be denoted by the same reference numerals and their description will be omitted.

[0071] [Outline configuration of projector and light source device] Figure 14 is a perspective view of the wavelength converter 5C of the projector light source device according to this embodiment, as seen from the incident side of the blue light BLs. Figure 15 is a schematic diagram showing a cross-section along the radial direction of the phosphor wheel 52C of the wavelength converter 5C. The projector according to this embodiment has the same configuration and functions as the projector according to the second embodiment, except that it is equipped with a wavelength converter 5C shown in Figures 14 and 15 in place of the wavelength converter 5B according to the second embodiment. In other words, the projector according to this embodiment has the same configuration and functions as the projector 1 according to the first embodiment, except that it is equipped with a wavelength converter 5C in place of the wavelength converter 5A according to the first embodiment. That is, the light source device according to this embodiment has the same configuration and functions as the light source device 3 according to the first embodiment, except that it is equipped with a wavelength converter 5C in place of the wavelength converter 5A.

[0072] [Configuration of the wavelength conversion device] The wavelength conversion device 5C has the same configuration and functions as the wavelength conversion device 5B according to the second embodiment, except that it is equipped with a phosphor wheel 52C instead of the phosphor wheel 52B according to the second embodiment. That is, the wavelength conversion device 5C is equipped with a rotating device 51 and a phosphor wheel 52C. The phosphor wheel 52C, like the phosphor wheel 52B, is rotated around the rotation axis Rx by the rotating device 51, and converts the wavelength of the blue light BLs as the first light to emit the fluorescent YL as the second light. The phosphor wheel 52C has the same configuration and function as the phosphor wheel 52B, except that it is equipped with a base material 61 instead of the base material 53 and the fixing member 60. That is, the phosphor wheel 52B comprises a base material 61, a wavelength conversion element 54, a phase change medium 55, a metal layer 56, an adhesive layer 57, a substrate 58, and a reflective layer 59.

[0073] [Composition of the base material] The base material 61 is fixed to the rotor 512 of the rotating device 51 and rotated together with the substrate 58 around the rotation axis Rx by the rotating device 51. The substrate 58 is fixed to the base material 61 by an adhesive layer 57 interposed between the substrate 58 and the base material 61. As shown in Figure 15, the base material 61 has a first surface 61A facing the +Z direction and a second surface 61B opposite to the first surface 61A, and also has an extension 611 and a bent portion 612 at its radially outer end 61E, but otherwise has the same configuration and function as the base material 53. That is, the base material 61 has a first surface 61A, a second surface 61B, a recess 533, an extension 611 and a bent portion 612, as well as an opening 531 and a plurality of fins 532, which are not shown in Figure 15.

[0074] The extension portion 611 is a part of the base material 61 that extends radially outward beyond the radially outer end 58E of the substrate 58. Therefore, the diameter of the base material 61 is larger than the diameter of the substrate 58. The bent portion 612 is the part that bends from the extended portion 611 toward the end portion 58E. That is, the bent portion 612 is the part that bends in a direction in which the tip of the extended portion 611 approaches the end portion 58E. The bent portion 612 is bent at approximately a right angle to the extension direction of the extended portion 611. However, it is not limited to this, and the bent portion 612 may be inclined toward the substrate 58 side and toward the end portion 58E as it extends toward the extension direction of the extended portion 611. Alternatively, the bent portion 612 may be inclined toward the substrate 58 side and toward the end portion 58E as it extends toward the extension direction of the extended portion 611.

[0075] In the wavelength conversion device 5C according to this embodiment, the metal layer 56 is provided on substantially the entire surface of the first surface 61A of the substrate 61. Therefore, the metal layer 56 is provided not only on the inner surface and periphery of the recess 533, but also on the surface facing the substrate 58 in both the extended portion 611 and the bent portion 612. Furthermore, the wavelength conversion device 5C according to this embodiment does not have a configuration that maintains the base material 61 and the substrate 58 facing each other, as is the case with the fixing member 60 according to the second embodiment. For this reason, in the wavelength conversion device 5C, the adhesive layer 57 interposed between the first surface 61A of the base material 61 and the second surface 58B of the substrate 58 to bond and fix the base material 61 and the substrate 58 is filled not only around the periphery of the recess 533, but also between the extended portion 611 and the bent portion 612 and the substrate 58.

[0076] [Effects of the third embodiment] The projector according to this embodiment, as described above, provides the same effects as the projector according to the second embodiment, as well as the following effects. In the wavelength conversion device 5C, of ​​the radially outer end 61E of the base material 61 and the radially outer end 58E of the substrate 58, the end 61E has an extended portion 611 and a bent portion 612. The extension portion 611 extends radially outward from the end portion 58E of the base material 61. The bent portion 612 bends from the extension portion 611 toward the end portion 58E. That is, the bent portion 612 is bent so that its tip is close to the end portion 58E. The end portion 61E corresponds to the first end portion, and the end portion 58E corresponds to the second end portion. With this configuration, even if centrifugal force acts on the phase change medium 55 when the base material 61 and substrate 58 rotate, causing the liquid phase change medium 55 to move radially outward from the base material 61 and substrate 58, the bent portion 612 can prevent the liquid phase change medium 55 from leaking out to the outside of the base material 61 and substrate 58.

[0077] [Fourth Embodiment] Next, a fourth embodiment of this disclosure will be described. The projector according to this embodiment has the same configuration as the projector according to the second embodiment, but the configuration of the wavelength conversion device is different. More specifically, the wavelength conversion device according to this embodiment differs in that it has a spiral recess. In the following description, parts that are the same or substantially the same as parts already described are denoted by the same reference numerals and their description is omitted.

[0078] [Outline configuration of projector and light source device] Figure 16 is a plan view of the wavelength converter 5D of the projector light source device according to this embodiment, as seen from the incident side of the blue light BLs. Note that the substrate 58 is not shown in Figure 16. The projector according to this embodiment has the same configuration and functions as the projector according to the second embodiment, except that it is equipped with a wavelength converter 5D shown in Figure 16 instead of the wavelength converter 5B according to the second embodiment. In other words, the light source device according to this embodiment has the same configuration and functions as the light source device according to the second embodiment, except that it is equipped with a wavelength converter 5D instead of the wavelength converter 5B. To put it another way, the projector and light source device according to this embodiment have the same configuration and functions as the projector 1 and light source device 3 according to the first embodiment, except that it is equipped with a wavelength converter 5D instead of the wavelength converter 5A according to the first embodiment.

[0079] [Configuration of the wavelength conversion device] The wavelength conversion device 5D has the same configuration and functions as the wavelength conversion device 5B according to the second embodiment, except that it is equipped with a phosphor wheel 52D instead of the phosphor wheel 52B according to the second embodiment. That is, the wavelength conversion device 5D is equipped with a rotating device 51 and a phosphor wheel 52D. The phosphor wheel 52D, like the phosphor wheel 52B, is rotated around the rotation axis Rx by the rotating device 51, and converts the wavelength of the blue light BLs as the first light to emit the fluorescence YL as the second light. The phosphor wheel 52D has the same configuration and function as the phosphor wheel 52B, except that it is equipped with a base material 62 instead of the base material 53 and fixing member 60. That is, the phosphor wheel 52B is equipped with a base material 62 as shown in Figure 16, as well as a wavelength conversion element 54, a phase change medium 55, a metal layer 56, an adhesive layer 57, a substrate 58, and a reflective layer 59, which are not shown in Figure 16.

[0080] [Composition of the base material] The base material 62 is fixed to the rotor 512 of the rotating device 51 and rotated together with the substrate 58 around the rotation axis Rx by the rotating device 51. The base material 62 has a first surface 62A facing the +Z direction and a second surface (not shown) located on the opposite side of the first surface 62A. The substrate 58 is fixed to the base material 62 by an adhesive layer 57 interposed between the second surface 58B and the first surface 62A of the substrate 58. The base material 62 has the same configuration and function as the base material 53, except that it has an opening 621 and a recess 622 instead of the opening 531, the plurality of fins 532 and the recess 533. That is, the base material 62 has a first surface 62A, a second surface (not shown), an opening 621 and a recess 622. The aperture 621, like the aperture 531, is formed in a roughly circular shape in the center of the base material 62 when viewed from the +Z direction, which is the incident side of the blue light BLs. A part of the rotor 512 of the rotating device 51 is inserted into the aperture 621 from the -Z direction.

[0081] Figure 17 shows the positional relationship between the recess 622 and the wavelength conversion element 54. In other words, Figure 17 is a view of the wavelength conversion device 5D, with the substrate 58 omitted, from the +Z direction. The recess 622 is provided in the first surface 62A of the base material 62 so as to be recessed in the -Z direction, and, similar to the recess 533 in the first to third embodiments, is a portion in which the phase change medium 55 is arranged. The recess 622 is formed in a spiral shape centered on the rotation axis Rx of the base material 62 over substantially the entire surface of the first surface 62A when viewed along the rotation axis Rx of the base material 62. As shown in Figure 17, the recess 622 is provided on the first surface 62A of the substrate 62 in a corresponding portion PT1 that corresponds to the wavelength conversion element 54 and a non-corresponding portion PT2 that does not correspond to the wavelength conversion element 54. That is, a part of the helical recess 622 is provided in the corresponding portion PT1, and the remaining part of the recess 622 is provided in the non-corresponding portion PT2, and the portion of the recess 622 located in the corresponding portion PT1 and the portion located in the non-corresponding portion PT2 are connected so that a liquid phase change medium can flow through them.

[0082] Such a recess 622 has a first channel 623 and a second channel 624. The first channel 623 is a channel that causes the liquid phase change medium 55, which has had heat transferred from the wavelength conversion element 54 by the rotation of the substrate 62, to flow from the corresponding portion PT1 to the non-corresponding portion PT2. The second channel 624 is in communication with the first channel 623 and is a channel that causes the liquid phase change medium 55 to flow from the non-corresponding section PT2 to the corresponding section PT1. The central end of the substrate 62 in the first channel 623 and the central end of the substrate 62 in the second channel 624 are connected in a way that allows the liquid phase change medium 55 to flow. Similarly, the outer edge end of the substrate 62 in the first channel 623 and the outer edge end of the substrate 62 in the second channel 624 are connected in a way that allows the liquid phase change medium 55 to flow. Therefore, the first channel 623 and the second channel 624 constitute a circulating channel through which the liquid phase change medium 55 circulates.

[0083] [Flow of phase change medium in recessed areas] The heat generated in the wavelength conversion element 54 when the first light, blue light BLs, is incident is transferred to the corresponding portion PT1 on the first surface 62A of the substrate 62 via the substrate 58. As a result, some of the solid phase change medium 55 located in the recess 622 melts and changes into liquid phase phase change medium 55. This phase change of the phase change medium 55 gradually spreads throughout the phase change medium 55 in the recess 622, and the liquid phase phase change medium 55 circulates in the first channel 623 and the second channel 624. As the base material 62 rotates, the liquid phase change medium 55 flows through the first channel 623 from the corresponding portion PT1 to the non-corresponding portion PT2, and the heat transferred to the phase change medium 55 is transported from the corresponding portion PT1 to the non-corresponding portion PT2. As the base material 62 rotates, the liquid phase change medium 55 flows through the second channel 624 from the non-corresponding portion PT2 to the corresponding portion PT1, resulting in the presence of a relatively low-temperature liquid phase change medium 55 in the corresponding portion PT1.

[0084] As the liquid phase change medium 55 circulates in this manner, it can be used as a heat transport medium to transport heat from the corresponding portion PT1 to the non-corresponding portion PT2, thereby preventing the temperature of the phase change medium 55 from becoming too high. Consequently, it becomes easier to maintain the state of the phase change medium 55 in a two-phase state of solid and liquid, and consequently, it becomes easier to maintain the temperature of the wavelength conversion element 54 within a predetermined range.

[0085] In this embodiment, the first channel 623 is configured to allow the liquid phase-change medium 55 to flow from the corresponding portion PT1 to the non-corresponding portion PT2, and the second channel 624 is configured to allow the liquid phase-change medium 55 to flow from the non-corresponding portion PT2 to the corresponding portion PT1. However, the embodiment is not limited to this configuration, and the second channel 624 may be configured as a channel through which the liquid phase-change medium 55 flows from the corresponding portion PT1 to the non-corresponding portion PT2, and the first channel 623 may be configured as a channel through which the liquid phase-change medium 55 flows from the non-corresponding portion PT2 to the corresponding portion PT1.

[0086] [Effects of the fourth embodiment] The projector according to this embodiment, as described above, provides the same effects as the projector according to the second embodiment, as well as the following effects. In the wavelength conversion device 5D, the recess 622 has a helical shape when viewed along the rotation axis Rx of the base material 62. The recess 622 is provided in the base material 62 in a corresponding portion PT1 that corresponds to the wavelength conversion element 54 and in a non-corresponding portion PT2 that does not correspond to the wavelength conversion element 54. The recess 622 has a first channel 623 and a second channel 624. The first channel 623 is a channel that moves the liquid phase change medium 55, which has been heated by the rotation of the substrate 62, from the corresponding portion PT1 to the non-corresponding portion PT2. The second channel 624 communicates with the first channel 623 and is a channel that moves the liquid phase change medium 55 from the non-corresponding portion PT2 to the corresponding portion PT1. The spiral recess 622 is a single channel through which the first channel 623 and the second channel 624 are connected to each other.

[0087] With this configuration, the phase change medium 55, which has changed from a solid phase to a liquid phase, can be flowed from the corresponding portion PT1 to the non-corresponding portion PT2 by the first channel 623, thereby dissipating heat from the liquid phase change medium 55 to the non-corresponding portion PT2, which is away from the wavelength conversion element 54. Then, the liquid phase change medium 55 that has dissipated heat in the non-corresponding portion PT2 can be flowed from the non-corresponding portion PT2 to the corresponding portion PT1 by the second channel 624, thereby circulating the liquid phase change medium 55 within the recess 622. In this way, the liquid phase change medium 55 can be used as a heat transport medium to transport heat from the corresponding portion PT1 to the non-corresponding portion PT2, so that the entire phase change medium 55 does not change into liquid phase change medium 55, and the temperature of the wavelength conversion element 54 located in the corresponding portion PT1 can be easily maintained within the above temperature range.

[0088] [Variations of the Embodiment] This disclosure is not limited to the embodiments described above, and any modifications and improvements that can achieve the purposes of this disclosure are included. In the embodiments described above, the phase change medium 55 was assumed to be a liquid metal. However, it is not limited to this, and the phase change medium 55 may be any substance other than a liquid metal, as long as the phase state of the phase change medium can be maintained in a two-phase state of liquid and solid phases, at least while the blue light BLs are incident on the wavelength conversion element 54.

[0089] In the first embodiment described above, the phase change medium 55 was also used as a reflective layer that reflects light incident from the wavelength conversion element 54. However, the phase change medium 55 is not limited to this and does not have to have reflective properties. In this case, for example, a reflective layer may be formed on the surface of the wavelength conversion element 54 opposite to the incident surface of the blue light BLs. An example of such a reflective layer is a reflective layer mainly composed of silver.

[0090] In the embodiments described above, the base materials 53, 61, and 62 are made of aluminum, and a metal layer 56, which serves as a corrosion-inhibiting layer, is provided between the base materials 53, 61, and 62 and the phase change medium 55. However, the embodiments are not limited to this, and the base materials 53, 61, and 62 may not contain aluminum and may be made of a metal or alloy other than aluminum. In this case, the metal layer 56 may be omitted.

[0091] In the first to third embodiments described above, the recess 533 is provided on the outer peripheral edge 5331 located radially outward of the base materials 53, 61, 62 in the recess 533, and has a plurality of protrusions 534 that extend radially outward from the base materials 53, 61, 62. However, the recess 533 is not limited to this, and does not have to have protrusions 534. On the other hand, each flow channel 623, 624 of the recess 622 in the fourth embodiment described above may have a plurality of protrusions 534.

[0092] In the first to third embodiments described above, the recess 533 is assumed to have a plurality of protrusions 534 having inclined surfaces 5341 and 5342. However, the recess 533 is not limited to this, and instead of a plurality of protrusions 534 arranged at equal intervals along the circumferential direction centered on the rotation axis Rx, the recess 533 may have a plurality of arc-shaped or wave-shaped protrusions. In this case, the plurality of protrusions may be provided at equal intervals along the circumferential direction centered on the rotation axis Rx on the outer peripheral edge 5331, or they may be provided randomly along the circumferential direction. The same applies to the recess 622. Furthermore, the circumferential dimensions of each of the multiple protrusions, centered on their respective rotation axis Rx, may differ from one another. The same applies to protrusion 534.

[0093] In the first to third embodiments described above, the depth of the radially outer portion of the base material 53,61 in the recess 533 was assumed to be smaller than the depth of the radially inner portion of the base material 53,61 in the recess 533. More specifically, the depth of the recess 533 was assumed to decrease from the radially inner portion of the base material 53,61 toward the radially outer portion. However, the depth of the recess 533 is not limited to this, and may be constant, or it may increase from the radially inner portion of the base material 53,61 toward the radially outer portion. Furthermore, such a change in depth may also be applied to the recess 622.

[0094] In the first to fourth embodiments described above, the phase change medium 55 was assumed to satisfy the above formula 1. However, the phase change medium 55 is not limited to this and does not need to satisfy the above formula 1.

[0095] In the second and third embodiments described above, the substrate 58, which is provided on the blue light BLs incident side, which is the first surface 53A, 61A, 62A side of the substrates 53, 61, 62, is configured as a disc shape when viewed along the rotation axis Rx and is fixed to the substrates 53, 61, 62 by an adhesive layer 57. However, the shape of the substrate 58 can be changed as appropriate, and is not limited to this. For example, the substrate 58 may be configured in a ring shape corresponding to the wavelength conversion element 54, supporting the wavelength conversion element 54, and may be placed on the substrates 53, 61 so as to cover the recess 533 in place of the wavelength conversion element 54 in the first embodiment. In this case, it is preferable that the substrate 58 is made of a metal other than aluminum.

[0096] In the second to fourth embodiments described above, the wavelength conversion devices 5B, 5C, and 5D are assumed to have a reflective layer 59 disposed between the wavelength conversion element 54 and the first surface 58A of the substrate 58. However, the invention is not limited to this, and the reflective layer 59 may be omitted if the first surface 58A has sufficient reflective properties, etc.

[0097] In the second to fourth embodiments described above, a metal layer 56 as a corrosion-inhibiting layer is provided on the second surface 58B of the substrate 58. However, the invention is not limited to this, and in cases where the substrate 58 is made of a metal or alloy other than aluminum, the metal layer 56 does not need to be provided on the second surface 58B.

[0098] In the second embodiment described above, the wavelength conversion device 5B is provided with a ring-shaped fixing member 60 that clamps the radially outer ends 53E and 58E of the base material 53 and the substrate 58, respectively. However, the fixing member 60 is not limited to this and may have other configurations such as screws, as long as it can fix the base material 53 and the substrate 58. Furthermore, the fixing member 60 may be omitted as long as it can fix the base material 53 and the substrate 58 and suppress leakage of the phase change medium 55 to the outside.

[0099] In the third embodiment described above, the base material 61 is provided at the radially outer end 61E and has an extension portion 611 that extends radially outward from the radially outer end 58E of the substrate 58, and a bent portion 612 that is bent toward the end 58E. However, the embodiment is not limited to this, and the substrate 58 may have an extension portion and a bent portion similar to the extension portion 611 and the bent portion 612, and the base material 61 may not have an extension portion 611 and a bent portion 612. The bent portion 612 may also be a folded portion that is bent from the extended portion 611 toward the end portion 58E. That is, the bent portion 612 only needs to extend in a direction intersecting the extended portion 611, and the bent portion 612 may be formed by bending the base material 61, or the base material 61 may be manufactured in advance so that the bent portion 612 is provided.

[0100] In the fourth embodiment described above, the helical recess 622 has a first flow path 623 and a second flow path 624, and the liquid phase change medium 55 circulates through the first flow path 623 and the second flow path 624. However, the embodiment is not limited to this, and the recess 622 only needs to be formed in a helical shape and arranged in the corresponding portion PT1 and the non-corresponding portion PT2, and does not necessarily have to include the first flow path 623 and the second flow path 624. Furthermore, the recesses 622 do not have to be helical; multiple recesses may be provided radially around the rotation axis Rx. In this case, each radially extending recess 622 may include a first flow path 623 and a second flow path 624.

[0101] In each of the embodiments described above, the first light was defined as blue light BLs, and the second light was defined as unpolarized light containing green and red light components. However, the invention is not limited to this, and the first light may be light with a different wavelength band and polarization state than the blue light BLs, and the same applies to the second light.

[0102] In the second to fourth embodiments described above, the phase change medium 55 was assumed to be located inside the recesses 533 and 622 in the substrates 53, 61, and 62. However, the invention is not limited to this, and the recesses 533 and 622 do not necessarily have to be provided in the substrates 53, 61, and 62. In this case, the phase change medium 55 may be sealed between the substrates 53, 61, and 62 and the substrate 58.

[0103] In each of the embodiments described above, the projector is assumed to be equipped with three optical modulators 243R, 243G, and 243B. However, the present disclosure is not limited to this and can also be applied to projectors equipped with two or fewer optical modulators, or four or more optical modulators.

[0104] In the embodiments described above, a transmissive liquid crystal panel with different light incident and light exit surfaces was exemplified as the optical modulator 243. However, a reflective liquid crystal panel with the same light incident and light exit surfaces may also be used. Furthermore, any optical modulator capable of modulating the incident light beam to form an image corresponding to image information may be used, such as a device using a micromirror, for example, a DMD (Digital Micromirror Device), or other optical modulators other than liquid crystals.

[0105] In the embodiments described above, examples were given in which the light source device of this disclosure is applied to a projector. However, the light source device according to this disclosure is not limited to this and may be used in electronic devices other than projectors, such as lighting fixtures and headlights of automobiles, etc.

[0106] [Summary of this disclosure] A summary of this disclosure is provided below. [Note 1] A substrate having a first surface, A rotating device for rotating the substrate, A wavelength conversion element is disposed on the first surface side of the substrate and converts first light having a first wavelength band into second light having a second wavelength band different from the first wavelength band. The phase change medium through which heat is transferred in the wavelength conversion element, Equipped with, The substrate has a recess provided on the first surface side of the substrate at a position corresponding to the wavelength conversion element, The phase change medium is sealed in the recess, The phase state of the phase-change medium is a two-phase state of liquid and solid phase, at least while the first light is incident on the wavelength conversion element. A wavelength conversion device characterized by the following features.

[0107] Here, the temperature of the phase change medium remains constant while the two-phase state described above is maintained. Therefore, since the temperature of the phase change medium remains approximately constant at least while the first light is incident on the wavelength conversion element, the temperature of the wavelength conversion element can be maintained within a predetermined range. Thus, by adjusting the composition and formulation of the phase change medium to control the temperature range in which the two-phase state of the phase change medium is maintained, the temperature of the wavelength conversion element can be maintained within a temperature range where the optical utilization efficiency of the wavelength conversion element is sufficiently high. Consequently, the optical utilization efficiency of the wavelength conversion element can be improved. Furthermore, because the recess in which the phase change medium is enclosed is provided at the above-mentioned position, heat from the wavelength conversion element can be easily transferred to the phase change medium.

[0108] [Note 2] In the wavelength conversion device described in Appendix 1, The phase change medium is a liquid metal, The liquid metal reflects the second light converted by the wavelength conversion element in a direction opposite to the incident direction of the first light incident on the wavelength conversion element. A wavelength conversion device characterized by the following features. With this configuration, a phase-change medium that is a liquid metal can be used as a reflective layer. Therefore, the configuration of the wavelength conversion device can be simplified compared to the case where a separate reflective layer is provided.

[0109] [Note 3] In the wavelength conversion device described in Appendix 1 or Appendix 2, The aforementioned substrate is made of aluminum, The substrate has a corrosion-inhibiting layer made of a metal other than aluminum, which is disposed between the substrate and the phase change medium on the first surface side. A wavelength conversion device characterized by the following features. In this case, if the phase change medium is a liquid metal, depending on the type of liquid metal, the phase change medium may corrode the aluminum, potentially causing corrosion of the substrate. In contrast, with the above configuration, corrosion of the substrate by the phase change medium can be suppressed by the corrosion-inhibiting layer made of a metal other than aluminum. Therefore, the wavelength conversion device can be used stably.

[0110] [Note 4] In the wavelength conversion device described in any one of the appendices 1 to 3, The recess is provided on the outer peripheral edge located radially outward of the substrate in the recess, and has a plurality of protrusions that extend radially outward of the substrate. A wavelength conversion device characterized by the following features. Here, when the substrate rotates, centrifugal force acts on the phase change medium sealed in the recess, causing the liquid phase change medium to flow into the multiple protrusions provided on the outer edge of the recess. This makes it easier to convect the liquid phase change medium within the recess, thus making it easier to equalize the temperature of the entire phase change medium to which heat is transferred, and thus maintaining the temperature of the phase change medium, and consequently the temperature of the wavelength conversion element, at a nearly constant level. Furthermore, by causing the phase change medium to flow, the liquid phase change medium can come into contact with the substrate, which is being rotated and cooled, thus promoting the re-solidification of the liquid phase change medium.

[0111] [Note 5] In the wavelength conversion device described in Appendix 4, Each of the aforementioned multiple protrusions has a plurality of inclined surfaces that intersect the radial direction of the substrate at different angles when viewed along the rotation axis of the substrate. A wavelength conversion device characterized by the following features. With this configuration, the direction of movement of the liquid phase change medium, which moves due to the centrifugal force acting on it when the substrate rotates, can be changed to a direction along the inclined surface. This promotes convection of the liquid phase change medium within the recess and prevents the liquid phase change medium from concentrating at the outer edge of the recess and leaking out of the recess.

[0112] [Note 6] In the wavelength conversion device described in any one of the appendices 1 to 5, The depth of the radially outer portion of the substrate in the recess is smaller than the depth of the radially inner portion of the substrate in the recess. A wavelength conversion device characterized by the following features. With this configuration, the varying depths of the recesses facilitate the movement of the liquid phase of the phase change medium within the recesses due to the centrifugal force acting on the phase change medium when the substrate rotates.

[0113] [Note 7] In the wavelength conversion device described in any one of the appendices 1 to 6, If Q is the amount of light per unit time of the first light incident on the wavelength conversion element, η is the conversion efficiency of the wavelength conversion element from the first light to the second light, ΔH is the heat of fusion of the phase change medium, ρ is the specific gravity of the phase change medium, t is the depth of the recess, n is the rotation speed of the substrate by the rotating device, d is the spot diameter of the first light incident on the wavelength conversion element, and D is the distance between the center of the spot of the first light irradiated on the wavelength conversion element and the rotation axis of the substrate, then the phase change medium satisfies the following equation 2: A wavelength conversion device characterized by the following features.

[0114]

number

[0115] With this configuration, the molten phase change medium is re-solidified by cooling due to the rotation of the substrate and the wavelength conversion element between the time the substrate completes one rotation and the time the first light is irradiated again in the same region of the wavelength conversion element, thereby allowing the phase change medium to repeatedly undergo melting and solidification. This makes it easier to control the temperature of the wavelength conversion element to any temperature based on the melting point of the phase change medium.

[0116] [Note 8] In a wavelength conversion device described in any one of the appendices 1 to 7, The substrate further comprises a substrate disposed on the first surface side of the aforementioned substrate, The aforementioned substrate is The first surface on which the wavelength conversion element is provided, The substrate has a second surface facing the first surface, A wavelength conversion device characterized by the following features. In this configuration, the phase change medium is sealed between a first surface of the substrate with a recess and a second surface of the substrate on which a wavelength conversion element is provided. As a result, since the wavelength conversion device is constructed by combining a substrate and a base material with relatively high strength, it is possible to manufacture the wavelength conversion device more easily compared to the case where the wavelength conversion element, which has a lower strength than the substrate and base material, is mounted on the first surface so as to cover the recess. Therefore, the ease of manufacturing the wavelength conversion device can be improved.

[0117] [Note 9] In the wavelength conversion device described in Appendix 8, The system further comprises a reflective layer disposed between the wavelength conversion element and the first surface, which reflects the second light converted by the wavelength conversion element. A wavelength conversion device characterized by the following features. With this configuration, light incident on the reflective layer from the wavelength conversion element can be returned to the wavelength conversion element by the reflective layer. As a result, when first light is incident on the reflective layer, the first light reflected by the reflective layer can be converted into second light by the wavelength conversion element. When second light is incident on the reflective layer, the second light reflected by the reflective layer can be emitted to the outside from the wavelength conversion element. Therefore, the utilization efficiency of the first light by the wavelength conversion element can be increased, and the diffusion of the second light emitted from the wavelength conversion element can be suppressed.

[0118] [Note 10] In the wavelength conversion device described in Appendix 8 or Appendix 9, The substrate is made of aluminum, The substrate has a metal layer provided on the second surface, which is made of a metal other than aluminum. A wavelength conversion device characterized by the following features. As described above, when the phase change medium is a liquid metal, depending on the type of liquid metal, contact between the liquid metal and aluminum can cause the aluminum to corrode. Therefore, depending on the type of phase change medium, there is a risk of corrosion of the substrate. In contrast, with the above configuration, corrosion of the substrate by the phase change medium can be suppressed by the metal layer made of a metal other than aluminum. Therefore, the wavelength conversion device can be used stably.

[0119] [Note 11] In the wavelength conversion device described in any one of the appendices 8 to 10, The system further includes a fixing member that clamps the radially outer end of the base material and the radially outer end of the substrate to fix the base material and the substrate together. A wavelength conversion device characterized by the following features. With this configuration, the radially outer end of the base material and the radially outer end of the substrate are held by the fixing member, so that the phase change medium located between the base material and the substrate does not leak out to the outside of the base material and the substrate.

[0120] [Note 12] In the wavelength conversion device described in any one of the appendices 8 to 10, Of the first radially outer end of the substrate and the second radially outer end of the substrate, one end is An extension that extends radially outward from the other end, It has a bent portion that is bent from the extended portion toward the other end, A wavelength conversion device characterized by the following features. With this configuration, even if centrifugal force acts on the phase change medium when the substrate and substrate rotate, causing the liquid phase change medium to move radially outward from the substrate and substrate, the bent portion can prevent the liquid phase change medium from leaking out to the outside of the substrate and substrate.

[0121] [Note 13] In the wavelength conversion device described in any one of the appendices 8 to 12, The recess is spiral in shape when viewed along the rotation axis of the substrate, and is provided in the substrate in a corresponding portion corresponding to the wavelength conversion element and a non-corresponding portion not corresponding to the wavelength conversion element. The aforementioned recess is A first channel that causes the phase change medium, which has had heat transferred from the wavelength conversion element by the rotation of the substrate, to flow from the corresponding portion to the non-corresponding portion, The device has a second channel that communicates with the first channel and causes the phase change medium to flow from the non-corresponding portion to the corresponding portion, A wavelength conversion device characterized by the following features.

[0122] With this configuration, the phase change medium, which has changed into a liquid phase, can be moved from the corresponding portion to the non-corresponding portion via the first channel, thereby dissipating heat from the liquid phase change medium to the non-corresponding portion away from the wavelength conversion element. Then, the liquid phase change medium can be moved from the non-corresponding portion to the corresponding portion via the second channel, thereby circulating the liquid phase change medium within the recess. In this way, the liquid phase change medium can be used as a heat transport medium to transport heat from the corresponding portion to the non-corresponding portion, so it is possible to suppress the complete transformation of the phase change medium into a liquid phase change medium, and it is possible to easily maintain the temperature of the wavelength conversion element located in the corresponding portion within the above temperature range.

[0123] [Note 14] The light source that emits the first light, The wavelength conversion device described in any one of Appendix 1 to Appendix 13, into which the first light emitted from the light source is incident, Equipped with, A light source device characterized by the following features. Such a light source device can achieve the same effects as the wavelength conversion device described above. This makes it possible to construct a light source device that is both highly luminous and has high conversion efficiency from the first light to the second light.

[0124] [Note 15] The light source device described in Appendix 14, A light modulator that modulates the light emitted from the light source device, A projection optical device that projects light modulated by the aforementioned optical modulation device, Equipped with, A projector characterized by the following features. Such a projector can achieve the same effect as the light source device described above. This makes it possible to construct a projector capable of projecting high-brightness images. [Explanation of Symbols]

[0125] 1...Projector, 243...Optical Modulator, 26...Projection Optical Device, 3...Light Source Device, 32...Light Source, 5A, 5B, 5C, 5D...Wavelength Conversion Device, 51...Rotating Device, 511...Rotating Device Body, 512...Rotor, 52A, 52B, 52C, 52D...Phosphor Wheel, 53...Substrate, 53A...First Surface, 53B...Second Surface, 53E...End, 531...Opening, 532...Fin, 533...Recess, 5331...Outer Edge, 5332...Inner Edge, 5333...Bottom Surface, 534...Convex Part, 5341, 534 2... Inclined surface, 54... Wavelength conversion element, 55... Phase change medium, 56... Metal layer (corrosion suppression layer), 57... Adhesive layer, 58... Substrate, 58A... First surface, 58B... Second surface, 58E... End, 59... Reflective layer, 60... Fixing member, 61... Base material, 61A... First surface, 61B... Second surface, 61E... End, 611... Extension, 612... Bent part, 62... Base material, 62A... First surface, 621... Opening, 622... Recess, 623... First channel, 624... Second channel, BLs... Blue light (first light), YL... Fluorescence (second light).

Claims

1. A substrate having a first surface, A rotating device for rotating the substrate, A wavelength conversion element is disposed on the first surface side of the substrate and converts first light having a first wavelength band into second light having a second wavelength band different from the first wavelength band. The phase change medium through which heat is transferred in the wavelength conversion element, Equipped with, The substrate has a recess provided on the first surface side of the substrate at a position corresponding to the wavelength conversion element, The phase change medium is sealed in the recess, The phase state of the phase-change medium is a two-phase state of liquid and solid phase, at least while the first light is incident on the wavelength conversion element. A wavelength conversion device characterized by the following features.

2. In the wavelength conversion apparatus according to claim 1, The phase change medium is a liquid metal, The liquid metal reflects the second light converted by the wavelength conversion element in a direction opposite to the incident direction of the first light incident on the wavelength conversion element. A wavelength conversion device characterized by the following features.

3. In the wavelength conversion device according to claim 1 or claim 2, The aforementioned substrate is made of aluminum, The substrate has a corrosion-inhibiting layer made of a metal other than aluminum, which is disposed between the substrate and the phase change medium on the first surface side. A wavelength conversion device characterized by the following features.

4. In the wavelength conversion device according to claim 1 or claim 2, The recess is provided on the outer peripheral edge located radially outward of the substrate in the recess, and has a plurality of protrusions that extend radially outward of the substrate. A wavelength conversion device characterized by the following features.

5. In the wavelength conversion apparatus according to claim 4, Each of the aforementioned multiple protrusions has a plurality of inclined surfaces that intersect the radial direction of the substrate at different angles when viewed along the rotation axis of the substrate. A wavelength conversion device characterized by the following features.

6. In the wavelength conversion device according to claim 1 or claim 2, The depth of the radially outer portion of the substrate in the recess is smaller than the depth of the radially inner portion of the substrate in the recess. A wavelength conversion device characterized by the following features.

7. In the wavelength conversion device according to claim 1 or claim 2, If Q is the amount of light per unit time of the first light incident on the wavelength conversion element, η is the conversion efficiency of the wavelength conversion element from the first light to the second light, ΔH is the heat of fusion of the phase change medium, ρ is the specific gravity of the phase change medium, t is the depth of the recess, n is the rotation speed of the substrate by the rotating device, d is the spot diameter of the first light incident on the wavelength conversion element, and D is the distance between the center of the spot of the first light irradiated on the wavelength conversion element and the rotation axis of the substrate, then the phase change medium satisfies the following equation 1: A wavelength conversion device characterized by the following features. [Math 1]

8. In the wavelength conversion device according to claim 1 or claim 2, The substrate further comprises a substrate disposed on the first surface side of the substrate, The aforementioned substrate is The first surface on which the wavelength conversion element is provided, The substrate has a second surface facing the first surface, A wavelength conversion device characterized by the following features.

9. In the wavelength conversion device according to claim 8, The system further comprises a reflective layer disposed between the wavelength conversion element and the first surface, which reflects the second light converted by the wavelength conversion element. A wavelength conversion device characterized by the following features.

10. In the wavelength conversion device according to claim 8, The substrate is made of aluminum, The substrate has a metal layer provided on the second surface, which is made of a metal other than aluminum. A wavelength conversion device characterized by the following features.

11. In the wavelength conversion device according to claim 8, The system further includes a fixing member that clamps the radially outer end of the base material and the radially outer end of the substrate to fix the base material and the substrate together. A wavelength conversion device characterized by the following features.

12. In the wavelength conversion device according to claim 8, Of the first radially outer end of the substrate and the second radially outer end of the substrate, one end is An extension that extends radially outward from the other end, It has a bent portion that is bent from the extended portion toward the other end, A wavelength conversion device characterized by the following features.

13. In the wavelength conversion device according to claim 8, The recess is spiral in shape when viewed along the rotation axis of the substrate, and is provided in the substrate in a corresponding portion corresponding to the wavelength conversion element and a non-corresponding portion not corresponding to the wavelength conversion element. The aforementioned recess is A first channel that causes the phase change medium, which has had heat transferred from the wavelength conversion element by the rotation of the substrate, to flow from the corresponding portion to the non-corresponding portion, A second channel is in communication with the first channel and causes the phase change medium to flow from the non-corresponding portion to the corresponding portion, A wavelength conversion device characterized by the following features.

14. The first light source that emits light, A wavelength conversion device according to claim 1 or claim 2, into which the first light emitted from the light source is incident, Equipped with, A light source device characterized by the following features.

15. The light source device according to claim 14, A light modulator that modulates the light emitted from the light source device, A projection optical device that projects light modulated by the aforementioned optical modulation device, Equipped with, A projector characterized by the following features.

Images