JP7724968B2 - lighting equipment - Google Patents

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Application No. 2022-112160 (filed July 13, 2022), the entire disclosure of which is incorporated herein by reference.

The present disclosure relates to a lighting device.

Light-emitting devices including a light source, a beam splitter, and a wavelength conversion member have been proposed (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2014-203852

A lighting device is disclosed.

In one embodiment, the lighting device includes one or more light sources, one or more wavelength conversion members, one or more wavelength separation filters, a light-guiding member, and a lens optical system. The light source emits excitation light. The excitation light from the light source is incident on the wavelength conversion member. The wavelength conversion member emits fluorescence having a spectrum different from that of the excitation light based on the excitation light. The wavelength separation filter guides the excitation light from the light source to the wavelength conversion member. The fluorescence from the wavelength conversion member is incident on the wavelength separation filter. The light-guiding member has a cylindrical surface, and the fluorescence from the wavelength separation filter travels inside the cylindrical surface while repeatedly reflecting off the cylindrical surface. The lens optical system includes a lens onto which the fluorescence emitted from the light-guiding member is incident, and forms an image of the emission surface of the light-guiding member on a virtual image plane.

FIG. 2 is a diagram schematically illustrating an example of an optical system of the illumination device according to the first embodiment. 1 is a cross-sectional view schematically illustrating an example of the configuration of an illumination device according to a first embodiment. 10 is a graph showing an example of the spectral transmittance of a wavelength separation filter. FIG. 2 is an enlarged cross-sectional view showing a part of the configuration of the lighting device. FIG. 2 is a diagram schematically illustrating a first aspect of an optical system of the illumination device according to the first embodiment. FIG. 4 is a diagram schematically illustrating a second aspect of the optical system of the illumination device according to the first embodiment. FIG. 10 is a diagram schematically illustrating a third aspect of the optical system of the illumination device according to the first embodiment. FIG. 10 is a diagram schematically illustrating an example of an optical system of an illumination device according to a second embodiment. 10A and 10B are diagrams schematically illustrating examples of arrangements of wavelength conversion members. FIG. 10 is a diagram schematically illustrating a first aspect of the configuration of an illumination device according to a second embodiment. 10 is a graph showing an example of the spectral transmittance of a first wavelength separation filter to a third wavelength separation filter. FIG. 10 is a diagram schematically illustrating a second mode of the optical system of the illumination device according to the second embodiment. FIG. 10 is a diagram schematically illustrating a third aspect of the optical system of the illumination device according to the second embodiment. FIG. 10 is a diagram schematically illustrating a fourth aspect of the optical system of the illumination device according to the second embodiment. FIG. 10 is a diagram schematically illustrating a fifth aspect of the optical system of the illumination device according to the second embodiment. FIG. 10 is a diagram schematically illustrating a sixth aspect of the optical system of the illumination device according to the second embodiment. FIG. 10 is a diagram schematically illustrating a seventh aspect of the optical system of the illumination device according to the second embodiment. FIG. 10 is a diagram schematically illustrating an eighth aspect of the optical system of the illumination device according to the second embodiment. FIG. 10 is a diagram schematically illustrating a ninth aspect of the optical system of the illumination device according to the second embodiment. 10A and 10B are diagrams schematically illustrating examples of an arrangement of wavelength conversion members and an irradiation area of excitation light. FIG. 1 is a diagram schematically illustrating an example of the configuration of a lighting device. FIG. 10 is a diagram schematically illustrating an example of an optical system of an illumination device according to a fourth embodiment. 10A and 10B are diagrams schematically showing other examples of the shape of the wavelength conversion member. FIG. 10 is a diagram schematically illustrating another aspect of the optical system of the illumination device according to the fourth embodiment. 10A and 10B are diagrams schematically showing other examples of the shape of the wavelength conversion member.

The inventor has developed a technology that allows a lighting device to emit more uniform illumination light. The following describes first to fourth embodiments of this technology with reference to the drawings.

In the drawings, parts with the same or similar configurations and functions are given the same reference numerals, and duplicate explanations will be omitted in the following description. The drawings are schematic. A right-handed XYZ coordinate system is appropriately indicated in each drawing. Below, one side of the X direction will also be referred to as the +X side, and the other side of the X direction will also be referred to as the -X side. The same or similar designations apply to the Y and Z directions.

1. First embodiment
<1-1. Schematic configuration of lighting device 1>
Fig. 1 is a diagram schematically illustrating an example of an optical system of an illumination device 1. Fig. 2 is a cross-sectional view schematically illustrating an example of the configuration of the illumination device 1.

As shown in Figure 2, the lighting device 1 is a device that emits fluorescence L1 as illumination light into the lighting space S1. The lighting device 1 is placed, for example, on the ceiling of the lighting space S1. As shown in Figures 1 and 2, the lighting device 1 includes a light source 2, a wavelength conversion member 3, a wavelength separation filter 4, a light-guiding member 5, a lens optical system 6, and a housing 7. Below, an example of each component will first be outlined, followed by a detailed description.

The housing 7 houses the light source 2, wavelength conversion member 3, wavelength separation filter 4, light-guiding member 5, and lens optical system 6. The housing 7 has a first opening (hereinafter also referred to as the irradiation opening) 7a at its -Z end, and fluorescence L1 as illumination light is emitted from the irradiation opening 7a into the illumination space S1.

As shown in FIG. 1, the light source 2 has an emission portion (e.g., an emission surface) 201 that emits excitation light L0. The excitation light L0 may be, for example, light having a peak in the wavelength range from 380 nm to 415 nm. As a specific example, the excitation light L0 may be purple light having a peak near 405 nm. Note that the excitation light L0 is not necessarily limited to purple light, and may be, for example, blue light having a peak near 450 nm.

Excitation light L0 from the light source 2 is incident on the wavelength separation filter 4. The wavelength separation filter 4 guides the excitation light L0 to the wavelength conversion member 3. In the example of Figures 1 and 2, the light source 2 and wavelength separation filter 4 are aligned along a first direction. The first direction is, for example, the X direction. In the example of Figures 1 and 2, the wavelength conversion member 3 and wavelength separation filter 4 are aligned along a second direction that intersects the first direction. The second direction is, for example, the Z direction. Here, the wavelength separation filter 4 reflects the excitation light L0 from the light source 2 toward the wavelength conversion member 3, and guides the excitation light L0 to the wavelength conversion member 3. The excitation light L0 is incident on the wavelength conversion member 3.

The wavelength conversion member 3 contains a phosphor. The wavelength conversion member 3 emits fluorescence L1 based on the incident excitation light L0. The fluorescence L1 has a spectrum different from that of the excitation light L0. Specifically, the peak wavelength of the fluorescence L1 is longer than the peak wavelength of the excitation light L0 (hereinafter also referred to as the excitation peak wavelength), and the fluorescence L1 is visible light. The fluorescence L1 travels from the wavelength conversion member 3 toward the wavelength separation filter 4 and is incident on the wavelength separation filter 4. In the example of Figures 1 and 2, the wavelength separation filter 4 transmits the fluorescence L1 from the wavelength conversion member 3.

The light-guiding member 5 has a cylindrical surface 5a. In the example of Figures 1 and 2, the central axis of the cylindrical surface 5a is along the Z direction. Fluorescence L1 from the wavelength separation filter 4 travels inside the area surrounded by the cylindrical surface 5a while repeatedly reflecting off the cylindrical surface 5a. As shown in Figure 2, fluorescence L1 emitted from the exit surface 5c (described below) of the light-guiding member 5 travels toward and enters the lens optical system 6.

The lens optical system 6 includes one or more lenses 61 positioned between the light-guiding member 5 and the illumination opening 7a. In the example of Figures 1 and 2, three lenses 61 are shown. The three lenses 61 are lined up in the Z direction between the light-guiding member 5 and the illumination opening 7a. The lens optical system 6 is an imaging optical system that forms an image of the object plane on a virtual image plane IS1 when the exit surface 5c of the light-guiding member 5 is the object plane. The image plane IS1 is located, for example, at the illumination opening 7a. The fluorescence L1 passes through the illumination opening 7a and is irradiated into the illumination space S1.

As described above, with the lighting device 1, the fluorescence L1 travels inside the light-guiding member 5 while being reflected by the cylindrical surface 5a of the light-guiding member 5. This results in a more uniform intensity distribution of the fluorescence L1 in a cross section perpendicular to the central axis of the cylindrical surface 5a (here, the XY cross section). Therefore, more uniform fluorescence L1 is emitted from the exit surface 5c of the light-guiding member 5. Ultimately, the lighting device 1 can emit more uniform fluorescence L1 as illumination light from the irradiation opening 7a.

Furthermore, according to the lighting device 1, the lens optical system 6 forms an image on the exit surface 5c of the light-guiding member 5 on a virtual image plane IS1. This allows the fluorescence L1 to be reduced in size on the image plane IS1. This makes it less likely that the fluorescence L1 will be reflected or scattered by the inner wall of the irradiation opening 7a of the housing 7, realizing a more uniform, high-quality illumination space S1 with less glare. Furthermore, the presence of the lighting device 1 when viewed from outside the irradiation opening 7a can be reduced.

Below, an example of each component of the lighting device 1 is described in detail.

<1-1-1. Light source 2>
The light source 2 may include, for example, a semiconductor laser element such as a laser diode (LD), or a light-emitting element such as a vertical cavity surface emitting laser (VCSEL), a light-emitting diode (LED), or a super luminescent diode (SLD). The emission unit 201 of the light source 2 may be the emission end of a light-emitting element. For example, a gallium nitride (GaN) semiconductor laser that emits 405 nm violet laser light as excitation light L0 may be used as the light-emitting element.

Alternatively, the light source 2 may further include a light-guiding member such as a fiber and a rod lens in addition to the light-emitting element. The fiber includes a linear core and cladding. The cladding has a lower refractive index than the core and covers the core. The excitation light L0 can pass through the core while being totally reflected at the boundary between the core and the cladding. The rod lens has, for example, a cylindrical shape. The excitation light L0 can pass through the rod lens while being totally reflected at the side of the rod lens. The input end of such a light-guiding member corresponds to the first end face of the fiber or the first end face of the rod lens, and the output end of the light-guiding member corresponds to the second end face opposite the first end face of the fiber or the second end face opposite the first end face of the rod lens. The excitation light L0 from the light-emitting element enters the input end of the light-guiding member, travels through the light-guiding member, and exits from the output end of the light-guiding member. In this case, the output portion 201 of the light source 2 corresponds to the output end of the light-guiding member.

The light source 2 may emit excitation light L0 having linear polarization. The polarization of the excitation light L0 may be, for example, s-polarized with respect to the incident plane of the wavelength separation filter 4. Various lenses may also be positioned between the light source 2 and the wavelength separation filter 4.

<1-1-2. Wavelength separation filter 4>
1 and 2, the wavelength separation filter 4 is arranged next to the light source 2 at a distance in the X direction and is located on the +X side of the light source 2. As described above, the wavelength separation filter 4 guides the excitation light L0 from the light source 2 to the wavelength conversion member 3, and the fluorescence L1 from the wavelength conversion member 3 is incident on the wavelength separation filter 4. In the example of FIGS. 1 and 2, the wavelength separation filter 4 reflects the excitation light L0 toward the wavelength conversion member 3 and transmits the fluorescence L1. The wavelength separation filter 4 is also called a dichroic mirror.

The wavelength separation filter 4 includes, for example, a dielectric multilayer film 401. For example, the dielectric multilayer film 401 has a structure in which dielectric thin films are repeatedly stacked. The dielectric may be, for example, one or more of silicon oxide (SiO ₂ ), titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), and niobium oxide (Nb ₂ O ₃ ). For example, by appropriately setting the thicknesses of the multiple dielectric thin films that make up the dielectric multilayer film 401, a spectral transmittance that reflects the excitation light L0 and transmits the fluorescence L1 in the dielectric multilayer film 401 can be achieved. In other words, the function of the wavelength separation filter 4 is substantially realized by the dielectric multilayer film 401.

Figure 3 is a graph showing an example of the spectral transmittance of the wavelength separation filter 4. Figure 3 shows the transmittance Ts of the wavelength separation filter 4 for s-polarized light and the transmittance Tn of the wavelength separation filter 4 for unpolarized light. Here, the polarization state of the excitation light L0 is s-polarized, and its wavelength is 405 nm. In the example of Figure 3, the transmittance Ts for the excitation light L0 is almost zero, so the excitation light L0 is hardly transmitted through the wavelength separation filter 4. For simplicity's sake, if the absorption rate of the wavelength separation filter 4 is assumed to be almost zero, the excitation light L0 is reflected by the wavelength separation filter 4 with a reflectance of almost 100%. On the other hand, the polarization state of the fluorescence L1 is unpolarized. The transmittance Tn in the wavelength range of the fluorescence L1 is almost 100%, so the fluorescence L1 is transmitted through the wavelength separation filter 4.

In the examples of Figures 1 and 2, the wavelength separation filter 4 is positioned so that the direction along its surface intersects the X direction at an angle close to approximately 45 degrees. In the examples of Figures 1 and 2, the wavelength separation filter 4 extends from the -X and -Z sides toward the +X and +Z sides. As a result, the direction of propagation of the excitation light L0 from the light source 2 changes by approximately 90 degrees before and after the wavelength separation filter 4. Specifically, the excitation light L0 from the light source 2 travels toward the +X side, is reflected by the wavelength separation filter 4, and travels toward the +Z side.

<1-1-3. Wavelength conversion member 3>
In the example of FIGS. 1 and 2, the wavelength conversion member 3 is arranged next to the wavelength separation filter 4 at an interval in the Z direction, and is located on the +Z side of the wavelength separation filter 4 .

The wavelength conversion member 3 includes a phosphor. The wavelength conversion member 3 may include, as a wavelength conversion material (i.e., a fluorescent material) that converts the excitation light L0 into blue light, for example, _BaMgAl10O17 :Eu, ( _Sr ,Ca,Ba) ₁₀ ( _PO4 ) _6Cl2 :Eu, (Sr,Ba) ₁₀ ( _PO4 ) _6Cl2 :Eu, or the like. _The wavelength conversion member 3 may include, as _a wavelength conversion material that converts the excitation light L0 into blue-green light, for example, (Sr,Ba,Ca) ₅ ( _PO4 ) _3Cl :Eu, _Sr4Al14O25 :Eu _, or _the like. The wavelength conversion member 3 _{may contain, for example, SrSi2(O,Cl)2N2:Eu, (Sr,Ba,Mg)2SiO4 : Eu2 +} ^, ZnS:Cu,Al, _Zn2SiO4 :Mn, etc. as a wavelength conversion material that converts the excitation light L0 to green light. The wavelength conversion member 3 may contain, for example, _Y2O2S :Eu, _{Y2O3 :} Eu, _SrCaClAlSiN3 : _Eu2 ⁺ , _CaAlSiN3 :Eu, CaAlSi(ON) ₃ :Eu, etc. as a wavelength conversion material that converts the excitation light _L0 to red light. The wavelength conversion member ₃ may contain _3Ga5O12 :Cr, etc. as _a wavelength conversion material that converts the excitation light L0 to light having a wavelength in the near-infrared region. If the wavelength conversion member 3 contains multiple types of wavelength converting materials corresponding to multiple colors of light, the wavelength conversion member 3 can emit fluorescence L1 with high color rendering. Specifically, if the excitation light L0 is light having a peak in the range of 380 nm to 415 nm and the wavelength conversion member 3 contains phosphors corresponding to red, green, and blue light, the color rendering of the fluorescence L1 can be particularly improved.

The wavelength conversion material 3 may also contain a resin such as a binder to connect the phosphor particles together.

The wavelength conversion member 3 has, for example, a surface 3a, a surface 3b, and a side surface 3c. Surface 3b is the surface of the wavelength conversion member 3 facing the wavelength separation filter 4. Surface 3a is the surface of the wavelength conversion member 3 opposite to surface 3b. Side surface 3c is the side surface connecting the periphery of surface 3a and the periphery of surface 3b of the wavelength conversion member 3. The wavelength conversion member 3 may have a plate-like shape. In other words, surfaces 3a and 3b of the wavelength conversion member 3 may be substantially flat surfaces and substantially parallel to each other. The wavelength conversion member 3 may be positioned such that its thickness direction is along the Z direction. In other words, surfaces 3a and 3b of the wavelength conversion member 3 may be substantially parallel to the XY plane.

<1-1-4. Light guide member 5>
1 and 2 , the light-guiding member 5 may include a first transparent member 51 and a second transparent member 52. The first transparent member 51 and the second transparent member 52 may be made of, for example, at least one of glass, such as optical glass, and resin, such as acrylic resin. The dielectric multilayer film 401 of the wavelength separation filter 4 is located between the first transparent member 51 and the second transparent member 52. The first transparent member 51 and the second transparent member 52 also function as a substrate supporting the dielectric multilayer film 401. Such a light-guiding member 5 also functions as a rod lens incorporating the wavelength separation filter 4.

The entire first transparent member 51 and the second transparent member 52 (i.e., the light-guiding member 5) may have, for example, a columnar shape. As a specific example, the light-guiding member 5 may have a rectangular columnar shape. The central axis of the light-guiding member 5 is, for example, approximately parallel to the Z direction. The light-guiding member 5 has a cylindrical surface 5a, an end surface 5b, and an exit surface 5c. The end surface 5b and the exit surface 5c are end surfaces located on both sides of the light-guiding member 5 in the longitudinal direction (i.e., the Z direction). The exit surface 5c is located on the -Z side of the end surface 5b, i.e., the lens optical system 6 side. The cylindrical surface 5a is a side surface connecting the periphery of the end surface 5b and the periphery of the exit surface 5c of the light-guiding member 5. The end surface 5b and the exit surface 5c may be flat surfaces, for example, or may be approximately parallel to each other. Furthermore, as shown in Figures 1 and 2, the end surface 5b of the light-guiding member 5 may be approximately parallel to the surface 3b of the wavelength conversion member 3. When the light guide member 5 has a quadrangular prism shape, the end face 5b and the light exit surface 5c have a quadrangular shape when viewed along the Z direction.

The first transparent member 51 and the second transparent member 52 are members obtained by dividing the light-guiding member 5 in two at the dielectric multilayer film 401 as the boundary. The first transparent member 51 has a first side surface 51a, which is part of the cylindrical surface 5a, a first inclined surface 51b, and an exit surface 5c. The first inclined surface 51b and the exit surface 5c are end surfaces located on both sides of the first transparent member 51 in the Z direction. The first inclined surface 51b is inclined with respect to the X direction at the same angle as the dielectric multilayer film 401. The exit surface 5c is located on the lens optical system 6 side of the first inclined surface 51b. The first side surface 51a is a side surface connecting the periphery of the first inclined surface 51b and the periphery of the exit surface 5c of the first transparent member 51. Such a first transparent member 51 has, for example, a columnar shape in which both end surfaces in the Y direction are right-angled trapezoids.

The second transparent member 52 has a second side surface 52a, which is the remaining portion of the cylindrical surface 5a, an end surface 5b, and a second inclined surface 52c. The second inclined surface 52c is inclined at the same degree as the first inclined surface 51b of the first transparent member 51 and faces the first inclined surface 51b. The second inclined surface 52c is approximately parallel to the first inclined surface 51b. The +X side end of the second inclined surface 52c is connected to the +X side end of the end surface 5b. The second side surface 52a is a side surface that connects the end surface 5b of the second transparent member 52 and the second inclined surface 52c. Such a second transparent member 52 has, for example, a columnar shape in which both end surfaces in the Y direction form a right-angled triangle.

The dielectric multilayer film 401 of the wavelength separation filter 4 is located between the first inclined surface 51b of the first transparent member 51 and the second inclined surface 52c of the second transparent member 52. In other words, the first inclined surface 51b and the second inclined surface 52c sandwich the dielectric multilayer film 401. The dielectric multilayer film 401 is formed on one of the first inclined surface 51b and the second inclined surface 52c. For example, the dielectric multilayer film 401 is formed by a physical vapor deposition method such as vacuum deposition, sputtering, or ion plating, or by a chemical vapor deposition method (CVD).

The first transparent member 51 and the second transparent member 52 may be fixed to each other via a fixing agent such as a transparent adhesive. For example, the dielectric multilayer film 401 may be formed on one of the first inclined surface 51b and the second inclined surface 52c, and the adhesive may be positioned between the other of the first inclined surface 51b and the second inclined surface 52c and the dielectric multilayer film 401. The adhesive may be, for example, a resin such as a photocurable resin.

Excitation light L0 from the light source 2 is incident on the second side surface 52a of the second transparent member 52 and travels from the second side surface 52a through the interior of the second transparent member 52 toward the wavelength separation filter 4. The excitation light L0 is reflected by the wavelength separation filter 4 and travels through the interior of the second transparent member 52 toward the end surface 5b. The excitation light L0 is emitted from the end surface 5b toward the wavelength conversion member 3 and is incident on the surface 3b of the wavelength conversion member 3. In other words, the end surface 5b can function as an emission surface for the excitation light L0.

In the example of Figures 1 and 2, fluorescence L1 from the wavelength conversion member 3 spreads as it travels toward the second transparent member 52 and is incident on the end face 5b of the second transparent member 52. Fluorescence L1 is refracted at the end face 5b and travels inside the second transparent member 52 toward the wavelength separation filter 4. In other words, the end face 5b also functions as the incident surface for fluorescence L1. Refraction at the end face 5b reduces the spread angle of fluorescence L1. In other words, the end face 5b can function as the end face of a focusing lens. Fluorescence L1 passes through the wavelength separation filter 4 and travels inside the first transparent member 51 toward the exit surface 5c. Fluorescence L1 is emitted from the exit surface 5c toward the lens optical system 6.

Fluorescence L1 travels from the end face 5b toward the exit surface 5c while repeatedly reflecting off the cylindrical surface 5a of the light-guiding member 5. As fluorescence L1 is repeatedly reflected, the intensity distribution of fluorescence L1 in a cross section perpendicular to the longitudinal direction of the light-guiding member 5 (here, the Z direction) becomes more uniform. As a result, more uniform fluorescence L1 is emitted from the exit surface 5c of the light-guiding member 5. It is also possible to reduce color unevenness of fluorescence L1 on the exit surface 5c.

By designing the light-guiding member 5 to be long, the uniformity of the fluorescence L1 at the exit surface 5c can be improved. The length of the light-guiding member 5 in the Z direction may be, for example, 10 mm or more.

Furthermore, in the specific example of the lighting device 1 in Figures 1 and 2, the first transparent member 51 from the wavelength separation filter 4 to the exit surface 5c is a single piece. "One piece" here means, for example, an object composed of a single member, rather than multiple members. If the first transparent member 51 is a single piece, there is no boundary surface (adhesive surface) between different members in the region from the wavelength separation filter 4 to the exit surface 5c. Therefore, loss of fluorescence L1 can be reduced, and the lighting device 1 can emit fluorescence L1 into the illumination space S1 with higher efficiency.

1 and 2, the area of the end face 5b of the light-guiding member 5 may be equal to or greater than the area of the surface 3b of the wavelength conversion member 3. For example, if the surface 3b of the wavelength conversion member 3 and the end face 5b of the light-guiding member 5 have a rectangular shape, the diagonal of the surface 3b may be approximately 2 mm to 4 mm, and the diagonal of the end face 5b may be approximately 4 mm to 15 mm or more. This allows more of the fluorescence L1 that spreads and travels from the surface 3b of the wavelength conversion member 3 to be incident on the end face 5b of the light-guiding member 5. Consequently, the lighting device 1 can emit the fluorescence L1 into the illumination space S1 with higher efficiency.

As shown in Figures 1 and 2, the wavelength conversion member 3 and the second transparent member 52 may be spaced apart from each other. The first distance between the surface 3b of the wavelength conversion member 3 and the end face 5b of the second transparent member 52 may be narrower than the second distance between the lens optical system 6 and the irradiation opening 7a, for example. The second distance is the distance between the lens 61 of the lens optical system 6 that is closest to the irradiation opening 7a and the irradiation opening 7a, for example. The first distance can be 5 mm or less, for example. The second distance can be 10 mm or more, for example. If the first distance is narrow, more of the light of the fluorescence L1 that spreads and travels from the wavelength conversion member 3 can be incident on the end face 5b of the second transparent member 52.

As shown in Figures 1 and 2, no other optical elements (e.g., lenses) may be positioned between the wavelength conversion member 3 and the second transparent member 52. This makes it easier to set a narrow first gap between the wavelength conversion member 3 and the second transparent member 52.

<1-1-5. Lens optical system 6>
In the example shown in FIGS. 1 and 2 , the lens optical system 6 is aligned with the light-guiding member 5 at a distance in the Z direction and is located on the −Z side of the light-guiding member 5. The lens 61 of the lens optical system 6 is located between the exit surface 5 c of the light-guiding member 5 and the irradiation opening 7 a of the housing 7. The lens 61 is formed of a material containing at least one of glass, such as optical glass, and resin, such as acrylic resin. As shown in FIGS. 1 and 2 , each lens 61 may be, for example, a biconvex lens. In the example shown in FIGS. 1 and 2 , the optical axis of the lens 61 is aligned along the Z direction. In other words, in the example shown in FIGS. 1 and 2 , the Z direction is the optical axis direction of the lens optical system 6. Note that the lens 61 is not limited to a convex lens, and may be a concave lens or a meniscus lens. The lens 61 may also be a spherical lens or an aspherical lens.

The lens optical system 6 is an imaging optical system that forms an image of the object plane on a virtual image plane IS1 when the exit surface 5c of the light-guiding member 5 is the object plane. In other words, in the example shown in Figures 1 and 2, three lenses 61 constitute the imaging optical system. The lenses 61 (particularly the lens 61 closest to the illumination aperture 7a) may also be referred to as imaging lenses. In the illumination device 1, the exit surface 5c of the light-guiding member 5 has a conjugate relationship with the image plane IS1. Note that the term "conjugate relationship" is not used in a strict sense; rather, the portion on the illumination aperture 7a side of the exit surface 5c of the light-guiding member 5 where the fluorescence L1 is most concentrated (the portion where the magnitude of the fluorescence L1 in the cross section perpendicular to the optical axis of the lens optical system 6 is smallest) can be considered to be the image plane IS1.

Image plane IS1 may be located, for example, at the illumination opening 7a. Image plane IS1 may be a flat surface or a curved surface. Fluorescence L1 is collected at image plane IS1 and emitted into illumination space S1 through the illumination opening 7a. Note that image plane IS1 does not necessarily have to be located inside the illumination opening 7a. Image plane IS1 may be located slightly offset from the illumination opening 7a in the direction of travel of fluorescence L1 passing through the illumination opening 7a (here, the Z direction). In other words, image plane IS1 may be located slightly inside the housing 7 relative to the illumination opening 7a, or slightly toward the illumination space S1.

In this lighting device 1, the imaging magnification of the lens optical system 6 is equal to or less than the ratio (M3/M1) of the size M1 of the fluorescence L1 at the exit surface 5c of the light-guiding member 5 to the size M3 of the irradiation opening 7a. The size M1 of the fluorescence L1 at the exit surface 5c of the light-guiding member 5 may be, for example, the size of the exit surface 5c of the light-guiding member 5 itself. The size M3 of the irradiation opening 7a is the opening area of the irradiation opening 7a as viewed along the Z direction. If the shape of the irradiation opening 7a as viewed along the Z direction is circular or rectangular, the diameter or diagonal length of the irradiation opening 7a may be, for example, approximately 5 mm to 15 mm. Note that if the surface forming the irradiation opening 7a is inclined, the size M3 of the irradiation opening 7a will vary at each position in the Z direction. In this case, the minimum value of the size M3 of the irradiation opening 7a may be used.

The imaging magnification is the ratio of the size M2 of the fluorescence L1 at the image plane IS1 to the size M1 of the fluorescence L1 at the exit surface 5c of the light-guiding member 5.

The magnitude of the fluorescence L1 may be defined by a contour line having a light intensity that is ^half e of the peak value in the light intensity distribution of the fluorescence L1 in a cross section perpendicular to the Z direction. Here, "e" is called the Napier's constant. In other words, the outermost light rays of the fluorescence L1 in FIG. 2 may be light rays having a light intensity that is ^half e of the peak value in the light intensity distribution in a cross section perpendicular to the optical axis AX1. Light in the region outside the region surrounded by the contour lines (i.e., the outermost light rays) may be regarded as noise light.

If the imaging magnification is equal to or less than the above ratio, the size M2 of the fluorescence L1 at the image plane IS1 can be made equal to or less than the size M3 of the illumination opening 7a. This reduces the likelihood that the fluorescence L1 will be incident on the peripheral portion of the illumination opening 7a in the housing 7. This reduces the amount of unnecessary reflected and scattered light that leaks out of the illumination opening 7a.

The imaging magnification of the lens optical system 6 may also be set so that the size of the fluorescence L1 passing through the irradiation opening 7a is smaller than the irradiation opening 7a. This further reduces reflected and scattered light.

Figure 4 is an enlarged cross-sectional view showing a portion of the configuration of the lighting device 1. In the lighting device 1, the divergence angle θ1 of the fluorescence L1 emitted from the exit surface 5c of the light-guiding member 5 may be less than or equal to the angle φ1 that defines the numerical aperture of the lens optical system 6. The numerical aperture is the product of the sine of half the value of the angle φ1 and the refractive index. The angle φ1 here is, for example, the angle formed by the two outer rays of virtual light passing through the effective area of the lens optical system 6. The effective area here corresponds to the area through which light passes through which the optical performance of the lens optical system 6 can be exhibited. For example, the effective area of the lens 61 is the area of the lens 61 excluding a predetermined peripheral width. As a more specific example, the effective area of the lens 61 may be the area surrounded by the inner peripheral edge of the part of the housing 7 that holds the peripheral edge of the lens 61 (i.e., the lens holder).

Because the divergence angle θ1 is less than or equal to the angle φ1, the fluorescence L1 can pass through the effective area of the lens optical system 6. Therefore, almost no fluorescence L1 is incident on the edge of the lens 61, and unnecessary reflection and scattering of the fluorescence L1 at the edge can be suppressed or avoided.

As described above, in the lighting device 1, the imaging magnification of the lens optical system 6 may be equal to or less than the above ratio, and the divergence angle θ1 may be equal to or less than the angle φ1. This suppresses or avoids unnecessary reflection and scattering of the fluorescence L1 at the periphery of the lens optical system 6 and the irradiation opening 7a. Therefore, the lighting device 1 can emit most of the fluorescence L1 from the light-guiding member 5 into the illumination space S1 through the irradiation opening 7a. In other words, the amount of fluorescence L1 emitted into the illumination space S1 can be improved. Furthermore, because the reflected and scattered light leaking into the illumination space S1 can be reduced, unevenness such as glare in the fluorescence L1 emitted into the illumination space S1 can be suppressed. In other words, the uniformity of the fluorescence L1 can be further improved. Therefore, the lighting device 1 can irradiate the illumination space S1 with highly efficient, high-quality fluorescence L1.

Furthermore, the divergence angle θ2 (see Figure 2) of the fluorescence L1 in the illumination space S1 may be smaller than the divergence angle θ1 of the fluorescence L1 entering the lens optical system 6 from the exit surface 5c of the light-guiding member 5. In other words, the lens optical system 6 may be designed so that the divergence angle θ2 is smaller than the divergence angle θ1. As a specific example, the orientation angle (e.g., half-value angle) of the fluorescence L1 in the illumination space S1 is, for example, approximately 60 degrees or less. The orientation angle of the lighting device 1 may be, for example, less than 45 degrees, less than 30 degrees, or less than 15 degrees. This makes it possible to reduce the glare of the lighting device 1 that enters the field of view in an illumination space S1 in which, for example, multiple lighting devices 1 are installed at regular intervals. As a result, the comfort of the illumination space S1 can be increased.

<1-2. First aspect>
FIG. 5 is a diagram schematically illustrating a first aspect of the optical system of the lighting device 1 according to the first embodiment. As shown in FIG. 5, the light source 2, wavelength separation filter 4, and wavelength conversion member 3 may be aligned in the X direction. In the example of FIG. 5, the light source 2 is located on the −X side of the wavelength separation filter 4, and the wavelength conversion member 3 is located on the +X side of the wavelength separation filter 4. Therefore, in this structure, the wavelength separation filter 4 transmits the excitation light L0 from the light source 2 toward the wavelength conversion member 3. The excitation light L0 transmitted through the wavelength separation filter 4 is incident on the wavelength conversion member 3. The fluorescence L1 emitted by the wavelength conversion member 3 travels toward the wavelength separation filter 4 and is incident on the wavelength separation filter 4. The wavelength separation filter 4 reflects the fluorescence L1 toward the −Z side. The fluorescence L1 reflected by the wavelength separation filter 4 travels inside the light-guiding member 5 toward the emission surface 5c while repeatedly reflecting off the cylindrical surface 5a of the light-guiding member 5.

<1-3. Second aspect>
6 is a diagram schematically illustrating a second aspect of the optical system of the illumination device 1 according to the first embodiment. As shown in FIG. 6, the wavelength separation filter 4 may include a dichroic prism incorporating a dielectric multilayer film 401. Specifically, the wavelength separation filter 4 includes the dielectric multilayer film 401, a first prism 402, and a second prism 403. The first prism 402 and the second prism 403 may be made of, for example, at least one of glass such as optical glass and resin such as acrylic resin.

The second prism 403 has a side surface 403a, an end surface 403b, and a second inclined surface 403c. The second prism 403 may have the same shape as the second transparent member 52 in FIG. 1. That is, the side surface 403a may be the same as the second side surface 52a of the second transparent member 52, the end surface 403b may be the same as the end surface 5b of the second transparent member 52, and the second inclined surface 403c may be the same as the second inclined surface 52c of the second transparent member 52. Such a second prism 403 may have, for example, a right-angled triangular prism shape in which both end surfaces in the Y direction are right-angled triangles. In the example of FIG. 6, the end surface 403b of the second prism 403 faces the surface 3b of the wavelength conversion member 3 in the Z direction.

The first prism 402 has a side surface 402a, a first inclined surface 402b, and an end surface 402c. The first inclined surface 402b is inclined to the same extent as the second inclined surface 403c of the second prism 403 and faces the second inclined surface 403c. The first inclined surface 402b is approximately parallel to the second inclined surface 403c. The end surface 402c is located on the light-guiding member 5 side of the first inclined surface 402b. The end surface 402c may be a flat surface approximately parallel to the XY plane. In the example of Figure 6, the -X side end of the end surface 402c is connected to the -X side end of the first inclined surface 402b. The side surface 402a is a side surface that connects the first inclined surface 402b and the end surface 402c of the first prism 402. The first prism 402 has a right-angled triangular prism shape with right-angled triangular end faces on both sides in the Y direction.

The dielectric multilayer film 401 is located between the first inclined surface 402b of the first prism 402 and the second inclined surface 403c of the second prism 403. For example, the dielectric multilayer film 401 is formed on one of the first inclined surface 402b and the second inclined surface 403c. The first prism 402 and the second prism 403 may be fixed to each other via a fixing agent such as a transparent adhesive. In this case, an adhesive may be located between the other of the first inclined surface 402b and the second inclined surface 403c and the dielectric multilayer film 401.

Such a wavelength separation filter 4 corresponds to the component having the dielectric multilayer film 401 among the components obtained by dividing the light-guiding member 5 in Figure 1 in two at the XY cross section.

In the example of Figure 6, the light-guiding member 5 includes a rod lens having a cylindrical shape. The end face 5b of the light-guiding member 5 (i.e., the rod lens) is located away from the wavelength separation filter 4 in the Z direction. The end face 5b of the light-guiding member 5 faces the end face 402c of the first prism 402 and is, for example, approximately parallel to the end face 402c. Fluorescence L1 from the wavelength separation filter 4 is incident on the end face 5b of the light-guiding member 5. The exit surface 5c is the side of the light-guiding member 5 opposite the end face 5b, that is, the surface facing the lens optical system 6. The exit surface 5c is, for example, approximately parallel to the end face 5b. The cylindrical surface 5a of the light-guiding member 5 is a side surface connecting the periphery of the end face 5b and the periphery of the exit surface 5c.

The wavelength separation filter 4 may be fixed to the light-guiding member 5 via a fixing agent such as a transparent adhesive. In this case, the adhesive may be located between the end face 402c of the first prism 402 and the end face 5b of the light-guiding member 5.

The dichroic prism that serves as the wavelength separation filter 4 in the second aspect is already available, and the rod lens that serves as the light-guiding member 5 is also already available. This means that the existing wavelength separation filter 4 and light-guiding member 5 can be used in the lighting device 1. This allows for a reduction in the manufacturing cost of the lighting device 1 in the second aspect.

In the second aspect, the area of the end face 403b of the second prism 403 may be equal to or greater than the area of the surface 3b of the wavelength conversion member 3. Furthermore, the first distance between the end face 403b of the second prism 403 and the surface 3b of the wavelength conversion member 3 may be narrower than the second distance between the lens optical system 6 and the irradiation opening 7a, for example. This allows more of the fluorescence L1 from the wavelength conversion member 3 to be incident on the end face 403b of the second prism 403.

<1-4. Third aspect>
7 is a diagram schematically illustrating a third aspect of the optical system of the illumination device 1 according to the first embodiment. As shown in FIG. 7, the wavelength separation filter 4 may have a plate-like shape. Specifically, the wavelength separation filter 4 includes a dielectric multilayer film 401 and a transparent substrate 404. The transparent substrate 404 may be made of, for example, at least one of glass such as optical glass and resin such as acrylic resin.

The transparent substrate 404 is aligned with the light-guiding member 5 at a distance in the Z direction. The transparent substrate 404 has a plate-like shape and has a surface 404a (corresponding to the first surface) and a surface 404b (corresponding to the second surface). Surface 404b is the surface of the transparent substrate 404 opposite to surface 404a. Surfaces 404a and 404b are approximately parallel to each other and are inclined at approximately 45 degrees with respect to the X direction. The dielectric multilayer film 401 is located, for example, on surface 404a or surface 404b of the transparent substrate 404.

As described above, according to the third aspect, the dielectric multilayer film 401 is located on a plate-shaped transparent substrate 404. This allows the volume of the transparent member to be small, thereby reducing the manufacturing cost of the wavelength separation filter 4.

In the third embodiment, a focusing lens may be positioned between the wavelength separation filter 4 and the wavelength conversion member 3. The fluorescence L1 from the wavelength conversion member 3 enters the wavelength separation filter 4 through the focusing lens. This allows more of the fluorescence L1 from the wavelength conversion member 3 to enter the wavelength separation filter 4.

<1-5. Other>
In the above example, the light-guiding member 5 is a so-called rod lens, but its shape may be changed as appropriate. For example, the light-guiding member 5 may have a prismatic shape such as a triangular prism, a quadrangular prism, a pentagonal prism, or a hexagonal prism, or may have a cylindrical shape.

Furthermore, the light-guiding member 5 is not limited to a rod lens, and may be other types of light-guiding member. For example, the light-guiding member 5 may be a fiber. A fiber includes a linear core and cladding. The cladding has a lower refractive index than the core and covers the core. The fluorescence L1 can pass through the core while being totally reflected at the cylindrical surface that is the boundary between the core and the cladding. Even when the light-guiding member 5 is a fiber, it may have the dielectric multilayer film 401 of the wavelength separation filter 4 built in.

The light-guiding member 5 may also be, for example, a lens barrel. The lens barrel has a cylindrical shape, and its inner peripheral surface, the cylindrical surface, is reflective. The fluorescence L1 can pass through the interior of the lens barrel while being totally reflected by the inner peripheral surface of the lens barrel. In this structure, the light-guiding member 5 may have a rectangular cylindrical shape, such as a triangular, square, pentagonal, or hexagonal cylindrical shape, or may have a cylindrical shape.

2. Second embodiment
8 is a diagram schematically illustrating an example of an optical system of an illumination device 1A according to the second embodiment. The illumination device 1A according to the second embodiment differs from the illumination device 1 according to the first embodiment in the number of wavelength conversion members 3 and light sources 2.

The lighting device 1A is equipped with multiple wavelength conversion members 3. In the example of Figure 8, the multiple wavelength conversion members 3 are shown as a first wavelength conversion member 31, a second wavelength conversion member 32, and a third wavelength conversion member 33. The first to third wavelength conversion members 31 to 33 emit fluorescence L1 having different spectra. For example, the first wavelength conversion member 31 contains a phosphor of a first color and emits fluorescence L1 of the first color. The first color is, for example, red. The second wavelength conversion member 32 contains a phosphor of a second color and emits fluorescence L1 of the second color. The second color is, for example, green. The third wavelength conversion member 33 contains a phosphor of a third color and emits fluorescence L1 of the third color. The third color is, for example, blue.

As shown in FIG. 8, the structure including the first wavelength conversion member 31 to the third wavelength conversion member 33 may face the wavelength separation filter 4 in the Z direction. In the example of FIG. 8, the structure faces the end face 5b of the light-guiding member 5 in the Z direction. Also, in the example of FIG. 8, the first wavelength conversion member 31 to the third wavelength conversion member 33 are arranged in this order in the X direction. In the example of FIG. 8, the first wavelength conversion member 31 is located furthest on the -X side, and the third wavelength conversion member 33 is located furthest on the +X side. The first wavelength conversion member 31 may be adjacent to the second wavelength conversion member 32 and be in contact with each other, and the second wavelength conversion member 32 may be adjacent to the third wavelength conversion member 33 and be in contact with each other. The first wavelength conversion member 31 to the third wavelength conversion member 33 correspond to, for example, the members obtained by dividing the wavelength conversion member 3 in FIG. 1 into third equal parts in the X direction.

As shown in Figure 8, multiple light sources 2 may be positioned in one-to-one correspondence with multiple wavelength conversion members 3. In the example of Figure 8, the multiple light sources 2 are a first light source 21, a second light source 22, and a third light source 23. As shown in Figure 8, the structure including the first light source 21 to the third light source 23 may be aligned with the wavelength separation filter 4 in the X direction. Also, the first light source 21 to the third light source 23 may be aligned in the Z direction. In the example of Figure 8, the first light source 21 is positioned closest to the -Z side, and the third light source 23 is positioned closest to the +Z side.

The excitation light L0 emitted by the first light source 21 enters the wavelength separation filter 4 and is guided by the wavelength separation filter 4 to the first wavelength conversion member 31. In the example of Figure 8, the excitation light L0 from the first light source 21 enters the second side surface 52a of the second transparent member 52 and travels from the second side surface 52a inside the second transparent member 52 toward the wavelength separation filter 4. The excitation light L0 is reflected by the wavelength separation filter 4 and travels inside the second transparent member 52 toward the end surface 5b. The excitation light L0 travels from the end surface 5b toward the first wavelength conversion member 31 and enters the first wavelength conversion member 31.

The excitation light L0 emitted by the second light source 22 enters the wavelength separation filter 4 and is guided by the wavelength separation filter 4 to the second wavelength conversion member 32. The excitation light L0 emitted by the third light source 23 enters the wavelength separation filter 4 and is guided by the wavelength separation filter 4 to the third wavelength conversion member 33.

The first wavelength conversion member 31 emits fluorescence L1 of a first color based on the excitation light L0 incident thereon. The second wavelength conversion member 32 emits fluorescence L1 of a second color based on the excitation light L0 incident thereon. The third wavelength conversion member 33 emits fluorescence L1 of a third color based on the excitation light L0 incident thereon. The fluorescence L1 emitted by the first wavelength conversion member 31, the second wavelength conversion member 32, and the third wavelength conversion member 33 spreads and travels toward the end face 5b of the second transparent member 52, where it is incident on the end face 5b of the second transparent member 52. This fluorescence L1 is refracted at the end face 5b and travels inside the second transparent member 52 toward the wavelength separation filter 4. The fluorescence L1 passes through the wavelength separation filter 4 and travels inside the first transparent member 51 toward the exit surface 5c. The fluorescence L1 travels inside the light-guiding member 5 toward the exit surface 5c while repeatedly reflecting off the cylindrical surface 5a, causing the first to third color fluorescence L1 to spatially mix. Therefore, the fluorescence L1 having a color in which the first color to the third color are mixed is emitted from the emission surface 5c of the light-guiding member 5. Therefore, the illumination device 1A can emit the fluorescence L1 having a color in which the first color to the third color are mixed from the irradiation opening 7a.

The first light source 21 to the third light source 23 may each emit excitation light L0 with a variable light intensity. For example, the first light source 21 includes a first light-emitting element such as an LD, VCSEL, SLD, or LED, and a first drive circuit that drives the first light-emitting element. The first drive circuit includes, for example, a switching power supply circuit, and supplies variable power to the first light-emitting element. The first light-emitting element emits excitation light L0 based on the power. Like the first light source 21, the second light source 22 also includes a second light-emitting element and a second drive circuit, and the third light source 23 also includes a third light-emitting element and a third drive circuit, like the first light source 21.

In the example of Figure 8, the first light source 21, the second light source 22, and the third light source 23 are controlled by a control unit 8. The control unit 8 may be, for example, a control board or a microcomputer. The microcomputer may be, for example, a large-scale integrated circuit (LSI) that integrates a central processing unit (CPU), memory, etc.

The control unit 8 may also be referred to as a control circuit. The control unit 8 includes at least one processor to provide control and processing power for performing various functions, as described in more detail below.

According to various embodiments, the at least one processor may be implemented as a single integrated circuit (IC) or as multiple communicatively connected integrated circuits ICs and/or discrete circuits. The at least one processor may be implemented according to various known techniques.

In one embodiment, a processor includes one or more circuits or units configured to perform one or more data computational procedures or processes, e.g., by executing instructions stored in associated memory. In other embodiments, a processor may be firmware (e.g., discrete logic components) configured to perform one or more data computational procedures or processes.

According to various embodiments, the processor may include one or more processors, controllers, microprocessors, microcontrollers, application specific integrated circuits (ASICs), digital signal processors, programmable logic devices, field programmable gate arrays, or any combination of these devices or configurations, or other known combinations of devices and configurations, to perform the functions described below.

In addition, all or some of the functions of the control unit 8 may be realized by a hardware circuit that does not require software to realize the function.

The control unit 8 can output control signals individually to the first drive circuit, the second drive circuit, and the third drive circuit. The control signals correspond to target values for the light intensity of the excitation light L0 emitted from the first light source 21, the second light source 22, and the third light source 23. The control unit 8 may control the operation of the first drive circuit, for example, in response to a signal from an external device (e.g., a lighting switch) of the lighting device 1A. For example, the control unit 8 receives a signal regarding the target value of the excitation light L0 from the external device and outputs a control signal corresponding to the signal to the first drive circuit. The first drive circuit drives the first light-emitting element based on the control signal, causing the first light-emitting element to emit excitation light L0 having a light intensity close to the target value. The control unit 8 can also control the operation of the second drive circuit and the third drive circuit, in the same way as the first drive circuit.

This allows the control unit 8 to individually adjust the light intensity of the fluorescence L1 emitted by the first wavelength conversion member 31 to the third wavelength conversion member 33. In other words, the proportions of the first color fluorescence L1, the second color fluorescence L1, and the third color fluorescence L1 in the fluorescence L1 emitted by the lighting device 1A can be changed. This allows the lighting device 1A to adjust the color of the fluorescence L1 emitted into the illumination space S1.

Moreover, in the above example, a single wavelength separation filter 4 is positioned for multiple wavelength conversion members 31. Therefore, the manufacturing cost of the lighting device 1A can be reduced compared to a structure in which multiple wavelength separation filters 4 corresponding to multiple wavelength conversion members 31 are used.

<2-1. Arrangement pattern of wavelength conversion member>
FIG. 9 is a diagram schematically illustrating an example of the arrangement of wavelength conversion members 3. FIG. 9 illustrates the shape of the wavelength conversion member 3 when viewed along the Z direction. As shown in FIG. 9( a), each of the first wavelength conversion member 31, the second wavelength conversion member 32, and the third wavelength conversion member 33 may have a rectangular shape when viewed along the Z direction. The first wavelength conversion member 31 to the third wavelength conversion member 33 are arranged in this order in the short-side direction. In the example of FIG. 9, the short-side direction is the X direction. As shown in FIG. 9( a), the second wavelength conversion member 32 may be adjacent to and in contact with the first wavelength conversion member 31 and the third wavelength conversion member 33. In the example of FIG. 9( a), the structure including the first wavelength conversion member 31 to the third wavelength conversion member 33 has a rectangular shape. As shown in FIG. 9( a), the first wavelength conversion member 31 to the third wavelength conversion member 33 may have approximately the same area and may have the same shape.

As shown in FIG. 9(b), the areas of the first wavelength conversion member 31, the second wavelength conversion member 32, and the third wavelength conversion member 33 may be different. For example, the area of the second wavelength conversion member 32 that emits fluorescence L1 of the second color (here, green) may be larger than the areas of both the first wavelength conversion member 31 and the third wavelength conversion member 33. Because green has a high luminosity, a structure in which the area of the second wavelength conversion member 32 that emits green fluorescence L1 as the second color is large allows the lighting device 1 to emit fluorescence L1 with higher brightness. As shown in FIG. 9(b), the first wavelength conversion member 31 and the third wavelength conversion member 33 may have approximately the same area or the same rectangular shape. 9(b), the first wavelength conversion member 31 and the third wavelength conversion member 33 are adjacent to each other in the Y direction, for example, and the second wavelength conversion member 32 is adjacent to both the first wavelength conversion member 31 and the third wavelength conversion member 33 in the X direction, for example. The second wavelength conversion member 32 may have the same rectangular shape as the overall shapes of the first wavelength conversion member 31 and the third wavelength conversion member 33. In the example of FIG. 9(b), the structure including the first wavelength conversion member 31 to the third wavelength conversion member 33 also has a rectangular shape.

Furthermore, among the multiple wavelength conversion members 3, the area of the wavelength conversion members 3 containing fluorescent materials with low heat resistance may be larger than the area of the wavelength conversion members 3 containing fluorescent materials with higher heat resistance than the fluorescent materials. In this case, the excitation light L0 can be incident on a wider irradiation area of the wavelength conversion members 3 with larger areas and lower heat resistance. Therefore, even if the power density of the excitation light L0 to the wavelength conversion members 3 is reduced, the wavelength conversion members 3 can emit a sufficient amount of fluorescence L1. Furthermore, reducing the power density of the excitation light L0 can mitigate the temperature rise of the wavelength conversion members 3. Therefore, even wavelength conversion members 3 with low heat resistance can emit fluorescence L1 with high reliability. On the other hand, by reducing the area of the wavelength conversion members with high heat resistance, the amount of fluorescent material can be reduced, thereby reducing the manufacturing cost of the lighting device 1A.

In the example of Figure 9 (b), the area of the second wavelength conversion member 32 is large, so the excitation light L0 can be incident on the second wavelength conversion member 32 over a wider range. This makes it possible to realize a lighting device 1A that is suitable for situations where the second color fluorescence L1 is used frequently.

As shown in Figure 9(c), each of the first wavelength conversion member 31 to the third wavelength conversion member 33 may have a circular shape. The first wavelength conversion member 31 to the third wavelength conversion member 33 may be circumscribing each other. In the example of Figure 9(c), the first wavelength conversion member 31 to the third wavelength conversion member 33 have approximately the same area.

As shown in FIG. 9(d), each of the first wavelength conversion member 31 to the third wavelength conversion member 33 may have a fan-like shape. In the example of FIG. 9(d), the first wavelength conversion member 31 to the third wavelength conversion member 33 have approximately the same area and a central angle of approximately 120 degrees. The first wavelength conversion member 31 to the third wavelength conversion member 33 are adjacent to each other with their centers aligned. A structure including such first wavelength conversion member 31 to the third wavelength conversion member 33 has a circular shape. In other words, the first wavelength conversion member 31 to the third wavelength conversion member 33 have a shape obtained by dividing a circle into three equal parts in the circumferential direction.

As shown in FIG. 9(e), the areas of the first wavelength conversion member 31 to the third wavelength conversion member 33 may be different. For example, the area of the second wavelength conversion member 32 that emits fluorescence L1 of the second color (here, green) may be larger than the areas of both the first wavelength conversion member 31 and the third wavelength conversion member 33. In the example of FIG. 9(e), the second wavelength conversion member 32 has a semicircular shape, and the first wavelength conversion member 31 and the third wavelength conversion member 33 have fan-shaped shapes with a central angle of approximately 90 degrees. In the example of FIG. 9(e), the structure including the first wavelength conversion member 31 to the third wavelength conversion member 33 also has a circular shape.

As shown in FIG. 9(f), the multiple wavelength conversion members 3 may include a first wavelength conversion member 31 and a second wavelength conversion member 32. The first wavelength conversion member 31 includes, for example, a phosphor made up of a mixture of multiple types of phosphors. The first wavelength conversion member 31 emits fluorescence L1 at a first color temperature that corresponds to the characteristics and mixing ratio of the multiple types of phosphors. For example, 2650 Kelvin (K) is applied as the first color temperature. The second wavelength conversion member 32 also includes, for example, a phosphor made up of a mixture of multiple types of phosphors. The second wavelength conversion member 32 emits fluorescence L1 at a second color temperature that corresponds to the characteristics and mixing ratio of the multiple types of phosphors. For example, 6500 K is applied as the second color temperature. Note that various color temperatures, such as 3000 K, 4000 K, or 5000 K, may be applied as the first or second color temperature.

In the example of Figure 9 (f), the first wavelength conversion member 31 and the second wavelength conversion member 32 have a rectangular shape and are arranged in contact with each other in their short direction (here, the X direction). The structure including the first wavelength conversion member 31 and the second wavelength conversion member 32 has a rectangular shape.

The multiple light sources 2 for this structure simply need to be a first light source 21 corresponding to the first wavelength conversion member 31 and a second light source 22 corresponding to the second wavelength conversion member 32. In other words, the third light source 23 is not required.

<2-2. First aspect>
Fig. 10 is a diagram schematically illustrating a first aspect of the configuration of an illumination device 1A according to the second embodiment. In the first aspect of the second embodiment, a plurality of wavelength separation filters 4 are positioned in one-to-one correspondence with a plurality of wavelength conversion members 3. In the example of Fig. 10, the plurality of wavelength separation filters 4 are positioned as a first wavelength separation filter 41, a second wavelength separation filter 42, and a third wavelength separation filter 43, which correspond respectively to a first wavelength conversion member 31, a second wavelength conversion member 32, and a third wavelength conversion member 33.

Each of the first wavelength separation filter 41 to the third wavelength separation filter 43 may be, for example, a dichroic prism, and specifically may include a dielectric multilayer film 401, a first prism 402, and a second prism 403.

In the example of Figure 10, the first light source 21, the first wavelength separation filter 41 and the first wavelength conversion member 31 are arranged in a first direction (here, the X direction), the second light source 22, the second wavelength separation filter 42 and the second wavelength conversion member 32 are arranged in the X direction, and the third light source 23, the third wavelength separation filter 43 and the third wavelength conversion member 33 are arranged in the X direction.

10, the light-guiding member 5 and the first to third wavelength separation filters 41 to 43 are aligned in the second direction (here, the Z direction). The first to third wavelength separation filters 41 to 43 are aligned in the Z direction in increasing order of distance from the light-guiding member 5. In other words, the first wavelength separation filter 41 is closest to the light-guiding member 5, and the third wavelength separation filter 43 is farthest from the light-guiding member 5. In other words, the shorter the peak wavelength of the fluorescence L1 emitted by the wavelength conversion member 3, the farther the corresponding wavelength separation filter 4 is located from the light-guiding member 5. For example, the third wavelength separation filter 43 corresponding to the third wavelength conversion member 33 that emits the third color fluorescence L1 with the shortest peak wavelength is located farthest from the light-guiding member 5. The light-guiding member 5 and the first to third wavelength separation filters 41 to 43 may be fixed to each other by, for example, a fixing agent such as an adhesive.

The third wavelength separation filter 43 guides the excitation light L0 from the third light source 23 toward the third wavelength conversion member 33, and also guides the third color fluorescence L1 from the third wavelength conversion member 33 toward the second wavelength separation filter 42. Specifically, the third wavelength separation filter 43 transmits the excitation light L0 from the third light source 23 toward the +X side, i.e., toward the third wavelength conversion member 33. On the other hand, the third wavelength separation filter 43 reflects the third color fluorescence L1 from the third wavelength conversion member 33 toward the -Z side, i.e., toward the second wavelength separation filter 42.

The second wavelength separation filter 42 guides the excitation light L0 from the second light source 22 to the second wavelength conversion member 32, and also guides both the third-color fluorescence L1 from the third wavelength separation filter 43 and the second-color fluorescence L1 from the second wavelength conversion member 32 to the first wavelength separation filter 41. Specifically, the second wavelength separation filter 42 transmits the excitation light L0 from the second light source 22 to the +X side, i.e., the second wavelength conversion member 32 side, and transmits the third-color fluorescence L1 from the third wavelength separation filter 43 to the -Z side, i.e., the first wavelength separation filter 41 side. The second wavelength separation filter 42 also reflects the second-color fluorescence L1 from the second wavelength conversion member 32 to the first wavelength separation filter 41 side.

The first wavelength separation filter 41 guides the excitation light L0 from the first light source 21 to the first wavelength conversion member 31, and also guides the second- and third-color fluorescence L1 from the second wavelength separation filter 42 and the first-color fluorescence L1 from the first wavelength conversion member 31 to the light-guiding member 5. Specifically, the first wavelength separation filter 41 transmits the excitation light L0 from the first light source 21 toward the +X side, i.e., the first wavelength conversion member 31 side, and transmits the second- and third-color fluorescence L1 from the second wavelength separation filter 42 toward the -Z side, i.e., the light-guiding member 5 side. The first wavelength separation filter 41 also reflects the first-color fluorescence L1 from the first wavelength conversion member 31 toward the light-guiding member 5 side.

Figure 11 is a graph showing an example of the spectral transmittance of the first wavelength separation filter 41 to the third wavelength separation filter 43. The example in Figure 11 shows the spectral transmittance T41 of the dielectric multilayer film 401 of the first wavelength separation filter 41, the spectral transmittance T42 of the dielectric multilayer film 401 of the second wavelength separation filter 42, and the spectral transmittance T43 of the dielectric multilayer film 401 of the third wavelength separation filter 43. The "light source wavelength" shown in Figure 11 indicates, for example, the excitation peak wavelength of the excitation light L0, and the "first fluorescence wavelength" to "third fluorescence wavelength" indicate, for example, the peak wavelengths of the first color to third color fluorescence L1, respectively. The first fluorescence wavelength is, for example, 610 nm or more and 800 nm or less, with 650 nm being a specific example. The second fluorescence wavelength is, for example, 510 nm or more and 590 nm or less, with 550 nm being a specific example. The third fluorescent wavelength is, for example, 460 nm or more and 490 nm or less, and a specific example is 480 nm. Note that, for simplicity, the description will be given ignoring the polarization state.

11, the dielectric multilayer film 401 of the first wavelength separation filter 41 to the third wavelength separation filter 43 may be a short-pass dichroic film. That is, the dielectric multilayer film 401 may transmit light with wavelengths shorter than a predetermined cutoff wavelength and reflect light with wavelengths longer than the cutoff wavelength. As a specific example, the cutoff wavelength λc1 of the spectral transmittance T41 is set between the first peak wavelength (i.e., the first fluorescent wavelength) of the first-color fluorescence L1 and the second peak wavelength (i.e., the second fluorescent wavelength) of the second-color fluorescence L1. The cutoff wavelength λc2 of the spectral transmittance T42 is set between the second fluorescent wavelength and the third peak wavelength (i.e., the third fluorescent wavelength) of the third-color fluorescence L1. The cutoff wavelength λc3 of the spectral transmittance T43 is set between the third fluorescent wavelength and the excitation peak wavelength (i.e., the light source wavelength) of the excitation light L0. The cutoff wavelength λc3 is set to a value greater than 440 nm and less than 460 nm, specifically 450 nm, for example. The dielectric multilayer film 401 of the third wavelength separation filter 43 transmits light in the wavelength range of 400 nm to 440 nm and reflects light in the wavelength range of 460 nm to 800 nm. The cutoff wavelength λc2 is set to a value greater than 490 nm and less than 510 nm, specifically 500 nm, for example. The dielectric multilayer film 401 of the second wavelength separation filter 42 transmits light in the wavelength range of 400 nm to 490 nm and reflects light in the wavelength range of 510 nm to 800 nm, for example. The cutoff wavelength λc1 is set to a value greater than 590 nm and less than 610 nm, specifically 600 nm, for example. The dielectric multilayer film 401 of the first wavelength separation filter 41 transmits light in the wavelength range of, for example, 400 nm or more and 590 nm or less, and reflects light in the wavelength range of 610 nm or more and 800 nm or less.

According to the spectral transmittance T43 in Figure 11, the third wavelength separation filter 43 transmits the excitation light L0 and reflects the third color (here, blue) fluorescence L1 from the third wavelength conversion member 33. This third color fluorescence L1 is incident on the second wavelength separation filter 42.

According to the spectral transmittance T42 in Figure 11, the second wavelength separation filter 42 transmits the excitation light L0 and the third color fluorescence L1 and reflects the second color (here, green) fluorescence L1 from the second wavelength conversion member 32. As a result, the second color fluorescence L1 and the third color fluorescence L1 mix and enter the first wavelength separation filter 41. In other words, the second wavelength separation filter 42 also functions as a combining element that combines the second color fluorescence L1 and the third color fluorescence L1 and guides the combined fluorescence L1 to the first wavelength separation filter 41.

According to the spectral transmittance T41 in Figure 11, the first wavelength separation filter 41 transmits the excitation light L0, the second color fluorescence L1, and the third color fluorescence L1, and reflects the first color (red in this case) fluorescence L1 from the first wavelength conversion member 31. As a result, the first to third color fluorescence L1 mix and enter the end face 5b of the light-guiding member 5. In other words, the first wavelength separation filter 41 also functions as a combining element that combines the first to third color fluorescence L1 and guides the combined fluorescence L1 to the light-guiding member 5.

Fluorescence L1 of the first to third colors travels from the end face 5b of the light-guiding member 5 through the interior of the light-guiding member 5 toward the exit surface 5c. Specifically, fluorescence L1 of the first to third colors travels through the interior of the light-guiding member 5 while being repeatedly reflected by the cylindrical surface 5a of the light-guiding member 5. This improves the uniformity of fluorescence L1 emitted from the exit surface 5c of the light-guiding member 5.

Furthermore, according to the first aspect of the second embodiment, the first wavelength separation filter 41, the second wavelength separation filter 42, and the third wavelength separation filter 43 are positioned corresponding to the first wavelength conversion member 31, the second wavelength conversion member 32, and the third wavelength conversion member 33, respectively. This allows the areas of the first wavelength conversion member 31 to the third wavelength conversion member 33 to be increased. This allows the areas of the irradiation regions of the excitation light L0 incident on each of the first wavelength conversion member 31 to the third wavelength conversion member 33 to be increased. Therefore, even if the power density of the excitation light L0 in the irradiation regions is reduced, each of the first wavelength conversion member 31 to the third wavelength conversion member 33 can emit fluorescence L1 with a sufficient amount of light. Furthermore, reducing the power density of the excitation light L0 reduces the temperature rise occurring in each of the first wavelength conversion member 31 to the third wavelength conversion member 33. This reduces the degree of thermal degradation of the first wavelength conversion member 31 to the third wavelength conversion member 33. That is, it is possible to reduce thermal deterioration of the first wavelength conversion member 31 to the third wavelength conversion member 33 while ensuring the light amount of the fluorescent light L1.

In the example of Figure 10, the shorter the peak wavelength of the fluorescence L1 emitted by the corresponding wavelength conversion member 3, the farther the wavelength separation filter 4 is located from the light-guiding member 5. As can be seen from Figure 11, a short-pass dichroic film can be used as the dielectric multilayer film 401 of the wavelength separation filter 4. The optical design of such a dielectric multilayer film 401 with a single cutoff wavelength is relatively easy.

Also, as shown in Figure 11, the first wavelength conversion member 31 to the third wavelength conversion member 33 may be located on the same side of the first wavelength separation filter 41 to the third wavelength separation filter 43, respectively. In the example of Figure 11, the first wavelength conversion member 31 is located on the +X side (corresponding to the first side) of the first wavelength separation filter 41, the second wavelength conversion member 32 is located on the +X side of the second wavelength separation filter 42, and the third wavelength conversion member 33 is located on the +X side of the third wavelength separation filter 43. For this reason, as shown in Figure 11, the first wavelength conversion member 31 to the third wavelength conversion member 33 can easily be attached to a common cooling member 75.

In the example of Figure 11, the cooling member 75 has a plate-like shape and is positioned with its thickness direction along the X direction. The cooling member 75 is positioned on the +X side of the wavelength conversion member 3, that is, on the opposite side from the wavelength separation filter 4. This cooling member 75 also functions as a support member that supports all of the first wavelength conversion member 31 to the third wavelength conversion member 33.

The cooling member 75 has a thermal conductivity higher than that of all of the first wavelength conversion member 31, the second wavelength conversion member 32, and the third wavelength conversion member 33. For example, the cooling member 75 is made of a metal material with high thermal conductivity. Examples of such metal materials include copper (Cu), aluminum (Al), magnesium (Mg), gold (Au), silver (Ag), iron (Fe), chromium (Cr), cobalt (Co), beryllium (Be), molybdenum (Mo), tungsten (W), and alloys. Such a cooling member 75 can function as a heat sink that cools the first wavelength conversion member 31 through the third wavelength conversion member 33. This reduces the degree of thermal degradation of the wavelength conversion member 31.

The first to third wavelength conversion members 31 to 33 may be directly bonded to the -X side surface 75a of the cooling member 75. For example, by forming phosphor pellets on the surface 75a of the cooling member by heat molding or the like, the surfaces 3a of the first to third wavelength conversion members 31 to 33 can be directly bonded to the surface 75a of the cooling member 75. In this way, if the cooling member 75 is directly bonded to the wavelength conversion member 3, the heat of the wavelength conversion member 3 can be transferred to the cooling member 75 more quickly. This further reduces the degree to which the wavelength conversion member 3 is deteriorated by heat.

In addition, in the first aspect, the first wavelength conversion member 31 to the third wavelength conversion member 33 are attached to a common cooling member 75, making it easy to assemble the lighting device 1A.

<2-3. Second aspect>
12 is a diagram schematically illustrating a second aspect of the optical system of the illumination device 1A according to the second embodiment. The illumination device 1A according to the second aspect of the second embodiment differs from the illumination device 1A of FIG. 10 in the positions of the light source 2, the wavelength separation filter 4, and the wavelength conversion member 3.

In the example of Figure 12, the arrangement order of the light source 2, wavelength separation filter 4, and wavelength conversion member 3 alternates as they move away from the light-guiding member 5. Specifically, in the example of Figure 12, the first light source 21, first wavelength separation filter 41, and first wavelength conversion member 31 are located in this order from the -X side to the +X side. On the other hand, the second light source 22, second wavelength separation filter 42, and second wavelength conversion member 32 are located in this order from the +X side to the -X side. In other words, the arrangement order of the second light source 22, second wavelength separation filter 42, and second wavelength conversion member 32 is reversed from that of the first light source 21, first wavelength separation filter 41, and first wavelength conversion member 31. The third light source 23, third wavelength separation filter 43, and third wavelength conversion member 33 are located in this order from the -X side to the +X side.

As a result, the inclination of the dielectric multilayer film 401 of the second wavelength separation filter 42 is opposite to the inclination of the dielectric multilayer film 401 of the first wavelength separation filter 41 and the third wavelength separation filter 43. In the example of Figure 12, the dielectric multilayer films 401 of the first wavelength separation filter 41 and the second wavelength separation filter 42 extend from the -X side and -Z side to the +X side and +Z side, and the dielectric multilayer film 401 of the second wavelength separation filter 42 extends from the -X side and +Z side to the +X side and -Z side. This allows the dielectric multilayer film 401 of the second wavelength separation filter 42 to reflect the second color fluorescence L1 from the second wavelength conversion member 32 toward the -Z side, i.e., toward the first wavelength separation filter 41.

As described above, according to the second aspect, the second wavelength conversion member 32 is located on the opposite side of the wavelength separation filter 4 in the X direction from the first wavelength conversion member 31 and the third wavelength conversion member 33. In other words, unlike the first wavelength conversion member 31 and the third wavelength conversion member 33, the second wavelength conversion member 32 is located on the -X side (corresponding to the second side) of the second wavelength separation filter 42. This allows the spacing between adjacent pairs of multiple wavelength conversion members 3 to be increased. The first wavelength conversion member 31 to the third wavelength conversion member 33 generate heat and function as a heat source, and the wide spacing between the wavelength conversion members 3 allows each wavelength conversion member 3 to be cooled more effectively.

<2-4. Third aspect>
13 is a diagram schematically illustrating a third aspect of the optical system of the illumination device 1A according to the second embodiment. The illumination device 1A according to the third aspect of the second embodiment differs from the illumination device 1A of FIG. 12 in the position of the third wavelength conversion member 33 and the characteristics of the third wavelength separation filter 43.

In the third aspect of the second embodiment, the third wavelength conversion member 33 faces the third wavelength separation filter 43 in the Z direction and is located on the +Z side of the third wavelength separation filter 43. In other words, the third wavelength conversion member 33 is located on the +Z side of the third wavelength separation filter 43, which is the farthest from the light-guiding member 5 in the Z direction. The third wavelength conversion member 33 is positioned with its thickness direction aligned with the Z direction.

The third wavelength separation filter 43 reflects the excitation light L0 from the third light source 23 toward the +Z side. As a result, the excitation light L0 travels toward the third wavelength conversion member 33 and is incident on the third wavelength conversion member 33. The third color fluorescence L1 emitted by the third wavelength conversion member 33 travels toward the third wavelength separation filter 43 and is incident on the third wavelength separation filter 43. The third wavelength separation filter 43 transmits the third color fluorescence L1 toward the -Z side. As a result, the third color fluorescence L1 travels toward the second wavelength separation filter 42.

<2-5. Fourth aspect>
Fig. 14 is a diagram schematically illustrating a fourth aspect of the optical system of the illumination device 1A according to the second embodiment. The illumination device 1A according to the fourth aspect of the second embodiment differs from the illumination device 1A in Fig. 10 in the structure of the wavelength separation filter 4.

In the fourth aspect of the second embodiment, the wavelength separation filter 4 includes three dielectric multilayer films 401: a first transparent member 410, a second transparent member 412, a third transparent member 423, and a fourth transparent member 430. The three dielectric multilayer films 401 correspond to the first wavelength conversion member 31 to the third wavelength conversion member 33, respectively. Hereinafter, the dielectric multilayer film 401 corresponding to the first wavelength conversion member 31 will be referred to as the first dielectric multilayer film 411, the dielectric multilayer film 401 corresponding to the second wavelength conversion member 32 will be referred to as the second dielectric multilayer film 421, and the dielectric multilayer film 401 corresponding to the third wavelength conversion member 33 will be referred to as the third dielectric multilayer film 431.

The spectral transmittance of the first dielectric multilayer film 411 is, for example, the same as the spectral transmittance T41 in Figure 11, the spectral transmittance of the second dielectric multilayer film 421 is, for example, the same as the spectral transmittance T42 in Figure 11, and the spectral transmittance of the third dielectric multilayer film 431 is, for example, the same as the spectral transmittance T43 in Figure 11. In other words, the first dielectric multilayer film 411 to the third dielectric multilayer film 431 essentially realize the functions of the first wavelength separation filter 41 to the third wavelength separation filter 43 in Figure 10, respectively.

In the example of Figure 14, the first dielectric multilayer film 411 is located between the first transparent member 410 and the second transparent member 412, the second dielectric multilayer film 421 is located between the second transparent member 412 and the third transparent member 423, and the third dielectric multilayer film 431 is located between the third transparent member 423 and the fourth transparent member 430. The material of the first transparent member 410, the second transparent member 412, the third transparent member 423, and the fourth transparent member 430 can be, for example, at least one of glass such as optical glass and resin such as acrylic resin.

The first transparent member 410 has a side surface 410a, an inclined surface 410b, and an end surface 410c. The end surface 410c faces the end surface 5b of the light-guiding member 5 in the Z direction and may be in contact with the end surface 5b. The end surface 410c may be approximately parallel to the end surface 5b. The inclined surface 410b of the first transparent member 410 is the surface opposite the end surface 410c and is inclined to the same extent as the first dielectric multilayer film 411. The side surface 410a is a side surface that connects the inclined surface 410b and the end surface 410c of the first transparent member 410. The first transparent member 410 may be, for example, a prism having a triangular prism shape with right-angled triangles as the end surfaces on both sides in the Y direction.

The second transparent member 412 has a side surface 412a, an inclined surface 412b, and an inclined surface 412c. The inclined surface 412c faces the inclined surface 410b of the first transparent member 410 and is approximately parallel to the inclined surface 410b. A first dielectric multilayer film 411 is located between the inclined surface 410b of the first transparent member 410 and the inclined surface 412c of the second transparent member 412. The first dielectric multilayer film 411 may be formed on one of the inclined surfaces 410b and 412c, and a fixing agent such as a transparent adhesive may be located between the other of the inclined surfaces 410b and 412c and the first dielectric multilayer film 411. The first dielectric multilayer film 411 is supported by the first transparent member 410 and the second transparent member 412.

The inclined surface 412b of the second transparent member 412 is the surface opposite to the inclined surface 412c and is approximately parallel to the inclined surface 412c. The side surface 412a is the side surface that connects the periphery of the inclined surface 412b with the periphery of the inclined surface 412c. The second transparent member 412 has, for example, a quadrangular prism shape in which both end faces in the Y direction are parallelograms.

The third transparent member 423 has a side surface 423a, an inclined surface 423b, and an inclined surface 423c. The shape of the third transparent member 423 is, for example, the same as the shape of the second transparent member 412. A second dielectric multilayer film 421 is located between the inclined surface 412b of the second transparent member 412 and the inclined surface 423c of the third transparent member 423. The second dielectric multilayer film 421 may be formed on one of the inclined surfaces 412b and 423c, and a fixing agent such as an adhesive may be located between the other of the inclined surfaces 412b and 423c and the second dielectric multilayer film 421. The second dielectric multilayer film 421 is supported by the second transparent member 412 and the third transparent member 423.

The fourth transparent member 430 has a side surface 430a, an end surface 430b, and an inclined surface 430c. The shape of the fourth transparent member 430 is, for example, the same as the shape of the first transparent member 410, and is positioned in a state inverted in the Z direction relative to the first transparent member 410. A third dielectric multilayer film 431 is positioned between the inclined surface 423b of the third transparent member 423 and the inclined surface 430c of the fourth transparent member 430. The third dielectric multilayer film 431 may be formed on one of the inclined surfaces 423b and 430c, and a fixing agent such as an adhesive may be positioned between the other of the inclined surfaces 423b and 430c and the third dielectric multilayer film 431. The third dielectric multilayer film 431 is supported by the third transparent member 423 and the fourth transparent member 430.

As described above, the second transparent member 412 is located between the first dielectric multilayer film 411 and the second dielectric multilayer film 421. Because the second transparent member 412 is a single piece, there is no boundary surface (adhesive surface) between different members in the area between the inclined surfaces 412b and 412c. This reduces the loss of fluorescence L1, allowing the lighting device 1A to emit fluorescence L1 into the illumination space S1 with higher efficiency. Because the third transparent member 423 between the second dielectric multilayer film 421 and the third dielectric multilayer film 431 is also a single piece, it reduces the loss of fluorescence L1.

Note that the first dielectric multilayer film 411 realizes the first wavelength separation filter 41 in Figure 11, and can therefore be said to be the dielectric multilayer film 401 of the first wavelength separation filter 41. Like the first dielectric multilayer film 411, the second dielectric multilayer film 421 is the dielectric multilayer film 401 of the second wavelength separation filter 42, and the third dielectric multilayer film 431 is the dielectric multilayer film 401 of the third wavelength separation filter 43. Therefore, in the fourth aspect of the second embodiment, it can be said that a second transparent member 412 formed from a single member is located between the dielectric multilayer film 401 of the first wavelength separation filter 41 and the second wavelength separation filter 42, and a third transparent member 423 formed from a single member is located between the dielectric multilayer film 401 of the second wavelength separation filter 42 and the third wavelength separation filter 43.

<2-6. Fifth aspect>
Fig. 15 is a diagram schematically illustrating a fifth aspect of the optical system of the illumination device 1A according to the second embodiment. The illumination device 1A according to the fifth aspect of the second embodiment differs from the illumination device 1A of Fig. 14 in the positions of the light source 2 and the wavelength conversion member 3. In the example of Fig. 15, the second wavelength conversion member 32 is located on the opposite side of the wavelength separation filter 4 in the X direction from the first wavelength conversion member 31 and the third wavelength conversion member 33. The second light source 22 is located on the opposite side of the wavelength separation filter 4 in the X direction from the first light source 21 and the third light source 23.

Therefore, the slope of the second dielectric multilayer film 421 is opposite to the slopes of the first dielectric multilayer film 411 and the third dielectric multilayer film 431. Because the sloped surface 412b of the second transparent member 412 and the sloped surface 423c of the third transparent member 423 are substantially parallel to the second dielectric multilayer film 421, the slope of the sloped surface 412b of the second transparent member 412 is opposite to the slope of the sloped surface 412c, and the sloped surface 423c of the third transparent member 423 is opposite to the slope of the sloped surface 423b. Therefore, the second transparent member 412 has, for example, a triangular prism shape with both end faces in the Y direction forming a right-angled isosceles triangle, and the third transparent member 423 has, for example, the same shape.

In the fifth aspect of the second embodiment, the second transparent member 412, which is formed from a single member, is located between the first dielectric multilayer film 411 and the second dielectric multilayer film 421, thereby reducing the loss of fluorescence L1. Furthermore, the third transparent member 423, which is also formed from a single member, is located between the second dielectric multilayer film 421 and the third dielectric multilayer film 431, thereby further reducing the loss of fluorescence L1.

<2-7. Sixth aspect>
Fig. 16 is a diagram schematically illustrating a sixth aspect of the optical system of the illumination device 1A according to the second embodiment. The illumination device 1A according to the sixth aspect of the second embodiment differs from the illumination device 1A of Fig. 10 in the configuration of the wavelength separation filter 4. In the example of Fig. 16, each of the first wavelength separation filter 41 to the third wavelength separation filter 43 includes a dielectric multilayer film 401 and a plate-shaped transparent substrate 404. This structure allows for a reduction in the manufacturing cost of each of the first wavelength separation filter 41 to the third wavelength separation filter 43.

A focusing lens may be located between the first wavelength separation filter 41 and the first wavelength conversion member 31. The first color fluorescence L1 from the first wavelength conversion member 31 enters the first wavelength separation filter 41 through the focusing lens. This allows more of the fluorescence L1 from the first wavelength conversion member 31 to enter the first wavelength separation filter 41. Focusing lenses may also be located between the second wavelength separation filter 42 and the second wavelength conversion member 32, and between the third wavelength separation filter 43 and the third wavelength conversion member 33.

<2-8. Seventh aspect>
17 is a diagram schematically illustrating a seventh aspect of the optical system of the illumination device 1A according to the second embodiment. The illumination device 1A according to the seventh aspect of the second embodiment differs from the illumination device 1A in FIG. 10 in the positions of the light source 2, the wavelength conversion member 3, and the wavelength separation filter 4.

As shown in FIG. 17, the second wavelength separation filter 42 may be aligned with the first wavelength separation filter 41 in the X direction. In the example of FIG. 17, the second wavelength separation filter 42 is located on the +X side of the first wavelength separation filter 41. Also, as shown in FIG. 17, the third wavelength separation filter 43 may be aligned with the second wavelength separation filter 42 in the Z direction. In the example of FIG. 17, the third wavelength separation filter 43 is located on the -Z side of the second wavelength separation filter 42, that is, on the light-guiding member 5 side. Therefore, the third wavelength separation filter 43 is adjacent to the light-guiding member 5 in the X direction. In the example of FIG. 17, the third wavelength separation filter 43 is located on the +X side of the light-guiding member 5. The light-guiding member 5 and the first wavelength separation filter 41 to the third wavelength separation filter 43 may be appropriately fixed, for example, with a fixing agent such as a transparent adhesive.

As shown in Figure 17, the third light source 23 may be aligned with the third wavelength separation filter 43 in the X direction, and the third wavelength conversion member 33 may be aligned with the third wavelength separation filter 43 in the Z direction. In the example of Figure 17, the third light source 23 is located on the +X side of the third wavelength separation filter 43, i.e., on the opposite side from the light-guiding member 5, and the third wavelength conversion member 33 is located on the -Z side of the third wavelength separation filter 43, i.e., on the opposite side from the second wavelength separation filter 42.

The third wavelength separation filter 43 reflects the excitation light L0 from the third light source 23 toward the -Z side, i.e., toward the third wavelength conversion member 33. On the other hand, the third wavelength separation filter 43 transmits the third color fluorescence L1 from the third wavelength conversion member 33 toward the +X side, i.e., toward the second wavelength separation filter 42.

As shown in Figure 17, the second light source 22 may be aligned with the second wavelength separation filter 42 in the Z direction, and the second wavelength conversion member 32 may be aligned with the second wavelength separation filter 42 in the X direction. In the example of Figure 17, the second light source 22 is located on the +Z side of the second wavelength separation filter 42, i.e., on the opposite side from the first wavelength separation filter 41, and the second wavelength conversion member 32 is located on the +X side of the second wavelength separation filter 42, i.e., on the opposite side from the first wavelength separation filter 41.

The second wavelength separation filter 42 reflects the excitation light L0 from the second light source 22 toward the +X side, i.e., toward the second wavelength conversion member 32. It also reflects the third color fluorescence L1 from the third wavelength separation filter 43 toward the -X side, i.e., toward the first wavelength separation filter 41. On the other hand, the second wavelength separation filter 42 transmits the second color fluorescence L1 from the second wavelength conversion member 32 toward the -X side, i.e., toward the first wavelength separation filter 41.

As shown in Figure 17, the first light source 21 may be aligned with the first wavelength separation filter 41 in the X direction, and the first wavelength conversion member 31 may be aligned with the first wavelength separation filter 41 in the Z direction. In the example of Figure 17, the first light source 21 is located on the -X side of the first wavelength separation filter 41, i.e., on the opposite side from the second wavelength separation filter 42, and the first wavelength conversion member 31 is located on the +Z side of the first wavelength separation filter 41, i.e., on the opposite side from the light-guiding member 5.

The first wavelength separation filter 41 reflects the excitation light L0 from the first light source 21 toward the +Z side, i.e., toward the first wavelength conversion member 31. It also reflects the second and third color fluorescence L1 from the second wavelength separation filter 42 toward the -Z side, i.e., toward the light-guiding member 5. On the other hand, the first wavelength separation filter 41 transmits the first color fluorescence L1 from the first wavelength conversion member 31 toward the -Z side, i.e., toward the light-guiding member 5.

As described above, in the example of Figure 17, the path of the third color fluorescence L1 passing through the third wavelength separation filter 43 and the first wavelength separation filter 41 in this order is formed in a U-shape.

Now, the second wavelength separation filter 42 is adjacent to the first wavelength separation filter 41 in the X direction. This allows the size of the lighting device 1A to be reduced in the Z direction. When the lighting device 1A is installed in an attic space, the lighting device 1A is installed in an orientation where the Z direction is along the vertical direction. However, the height of the attic space may be low. Specifically, the height of the attic space may be approximately 10 cm. As described above, if the size of the lighting device 1A in the Z direction can be reduced, the lighting device 1A can be easily installed in a low-height attic space.

Furthermore, in the above example, the third wavelength separation filter 43 is located on the -Z side relative to the second wavelength separation filter 42. This allows the size of the lighting device 1A in the Z direction to be further reduced. This makes it even easier to install the lighting device 1A in a low-height space above the ceiling.

Also, in the example of Figure 17, the shorter the peak wavelength of the fluorescence L1, the farther the wavelength separation filter 4 is from the light-guiding member 5 in the U-shaped path of the fluorescence L1. For example, the third wavelength separation filter 43 is located farthest from the light-guiding member 5 in the U-shaped path of the third-color fluorescence L1. This allows the first wavelength separation filter 41, the second wavelength separation filter 42, and the third wavelength separation filter to be configured with a dielectric multilayer film 401 having a simple spectral transmittance with a single cutoff wavelength. However, as can be understood from the above explanation, a long-pass dichroic film that reflects short-wavelength light and transmits long-wavelength light is used for the dielectric multilayer film 401.

<2-9. Eighth aspect>
Fig. 18 is a diagram schematically illustrating an eighth aspect of the optical system of the illumination device 1A according to the second embodiment. The illumination device 1A according to the eighth aspect of the second embodiment differs from the illumination device 1A of Fig. 10 in the positions of the light source 2, the wavelength conversion member 3, and the wavelength separation filter 4, and in the presence or absence of a combining element 45.

Fluorescence L1 from the first wavelength separation filter 41 to the third wavelength separation filter 43 enters the combining element 45 from different directions. That is, the first color fluorescence L1 from the first wavelength separation filter 41 enters the combining element 45 without passing through either the second wavelength separation filter 42 or the third wavelength separation filter 43. Fluorescence L1 of the second and third colors also enters the combining element 45. The combining element 45 is an optical element that combines the fluorescence L1 from the first wavelength separation filter 41, the second wavelength separation filter 42, and the third wavelength separation filter 43 and guides it to the end face 5b of the light-guiding member 5. The combining element 45 is, for example, a cross prism. The combining element 45 is aligned with the light-guiding member 5 in the Z direction and is located on the +Z side of the light-guiding member 5.

As shown in Figure 18, the first wavelength separation filter 41 may be aligned with the combining element 45 in the X direction, and in the example of Figure 18, it is located on the +X side of the combining element 45. The second wavelength separation filter 42 may be aligned with the combining element 45 in the Z direction, and in the example of Figure 18, it is located on the +Z side of the combining element 45, i.e., on the opposite side from the light-guiding member 5. The third wavelength separation filter 43 may be aligned with the combining element 45 in the X direction, and in the example of Figure 18, it is located on the +Z side of the combining element 45, i.e., on the opposite side from the first wavelength separation filter 41. As described above, multiple wavelength separation filters 4 and light-guiding members 5 may be arranged to surround the combining element 45.

As shown in Figure 18, the first light source 21 may be aligned with the first wavelength separation filter 41 in the Z direction, and the first wavelength conversion member 31 may be aligned with the first wavelength separation filter 41 in the X direction. In the example of Figure 18, the first light source 21 is located on the -Z side of the first wavelength separation filter 41, and the first wavelength conversion member 31 is located on the +X side of the first wavelength separation filter 41, i.e., on the opposite side from the combining element 45.

The first wavelength separation filter 41 reflects the excitation light L0 from the first light source 21 toward the +X side, i.e., toward the first wavelength conversion member 31. On the other hand, the first wavelength separation filter 41 transmits the first color fluorescence L1 from the first wavelength conversion member 31 toward the -X side, i.e., toward the combining element 45.

As shown in Figure 18, the second light source 22 may be aligned with the second wavelength separation filter 42 in the X direction, and the second wavelength conversion member 32 may be aligned with the second wavelength separation filter 42 in the Z direction. In the example of Figure 18, the second light source 22 is located on the +X side of the second wavelength separation filter 42, and the second wavelength conversion member 32 is located on the +Z side of the second wavelength separation filter 42, i.e., on the opposite side from the combining element 45.

The second wavelength separation filter 42 reflects the excitation light L0 from the second light source 22 toward the +Z side, i.e., toward the second wavelength conversion member 32. On the other hand, the second wavelength separation filter 42 transmits the second color fluorescence L1 from the second wavelength conversion member 32 toward the -Z side, i.e., toward the combining element 45.

As shown in Figure 18, the third light source 23 may be aligned with the third wavelength separation filter 43 in the Z direction, and the third wavelength conversion member 33 may be aligned with the third wavelength separation filter 43 in the X direction. In the example of Figure 18, the third light source 23 is located on the +Z side of the third wavelength separation filter 43, and the third wavelength conversion member 33 is located on the -X side of the third wavelength separation filter 43, i.e., on the opposite side from the combining element 45.

The third wavelength separation filter 43 reflects the excitation light L0 from the third light source 23 toward the -X side, i.e., toward the third wavelength conversion member 33. On the other hand, the third wavelength separation filter 43 transmits the third color fluorescence L1 from the third wavelength conversion member 33 toward the +X side, i.e., toward the combining element 45.

As described above, the first, second, and third color fluorescence L1 enter the confluence element 45 from three directions. The confluence element 45 guides the first, second, and third color fluorescence L1 to the -Z side, i.e., the light-guiding member 5 side.

As shown in FIG. 18, the combining element 45 may include a first dielectric multilayer film 451, a second dielectric multilayer film 452, and a first prism 453 to a fourth prism 456.

The first dielectric multilayer film 451 and the second dielectric multilayer film 452 intersect in a cross shape. For example, the first dielectric multilayer film 451 is positioned with its surface extending from the -X and -Z sides to the +X and +Z sides, and the second dielectric multilayer film 452 is positioned with its surface extending from the -X and +Z sides to the +X and -Z sides. The first dielectric multilayer film 451 reflects the first-color fluorescence L1 from the first wavelength conversion member 31 toward the -Z side, while transmitting the second-color fluorescence L1 from the second wavelength conversion member 32 and the third-color fluorescence L1 from the third wavelength conversion member 33. The second dielectric multilayer film 452 reflects the third-color fluorescence L1 from the third wavelength conversion member 33 toward the -Z side, while transmitting the first-color fluorescence L1 from the first wavelength conversion member 31 and the second-color fluorescence L1 from the second wavelength conversion member 32.

With this combining element 45, the first color fluorescence L1 is reflected toward the -Z side by the combining element 45, the second color fluorescence L1 is transmitted through the combining element 45 toward the -Z side, and the third color fluorescence L1 is reflected toward the -Z side by the combining element 45. As a result, the first, second, and third color fluorescence L1 combined by the combining element 45 are incident on the end surface 5b of the light-guiding member 5.

In the example of Figure 18, the first prism 453 to the fourth prism 456 have, for example, a triangular prism shape with both end faces in the Y direction forming right-angled isosceles triangles, and are positioned so that their vertices approximately coincide. The first prism 453 is located on the -Z side of the vertex, the second prism 454 is located on the -X side, the third prism 455 is located on the +Z side, and the fourth prism 456 is located on the +X side. The first dielectric multilayer film 451 is located between the first prism 453 and the second prism 454 and between the third prism 455 and the fourth prism 456, and the second dielectric multilayer film 452 is located between the second prism 454 and the third prism 455 and between the first prism 453 and the fourth prism 456.

According to the eighth aspect of the second embodiment, the first wavelength separation filter 41 and the third wavelength separation filter 43 are aligned in the X direction. This allows the size of the lighting device 1A in the Z direction to be reduced.

Furthermore, each of the first wavelength separation filter 41 to the third wavelength separation filter 43 only needs to reflect the excitation light L0, and does not need to reflect the fluorescence L1. In other words, each of the first wavelength separation filter 41 to the third wavelength separation filter 43 may be able to transmit the first to third color fluorescence L1. Therefore, the cutoff frequency of the dielectric multilayer film 401 of the first wavelength separation filter 41 to the third wavelength separation filter 43 only needs to be located between the excitation peak wavelength of the excitation light L0 and the third peak wavelength of the third color fluorescence L1. In other words, filters with the same specifications can be used for the first wavelength separation filter 41 to the third wavelength separation filter 43. This simplifies component management.

<2-10. Ninth aspect>
In the wavelength separation filter 4, an air gap may be located between the dielectric multilayer film 401 and the transparent member. For example, in the lighting device 1A of Fig. 17, in at least one of the first wavelength separation filter 41 to the third wavelength separation filter 43, an air gap may be located between the first prism 402 and the second prism 403. As a specific example, the dielectric multilayer film 401 may be formed on the first prism 402, and an air gap may be located between the dielectric multilayer film 401 and the second prism 403.

This reduces the wavelength dependence of the spectral transmittance of the wavelength separation filter 4.

3. Third Embodiment
Fig. 19 is a diagram schematically illustrating an example of an optical system of an illumination device 1B according to the third embodiment. The illumination device 1B differs from the illumination device 1A of Fig. 8 in the number of light sources 2 and the presence or absence of a driving unit 25. As shown in Fig. 19, the illumination device 1B may be provided with a single light source 2.

The drive unit 25 displaces the light source 2 to change the irradiation area of the excitation light L0 in the wavelength conversion member 3. For example, the drive unit 25 may move the light source 2 along the Z direction. By moving the light source 2 along the Z direction, the irradiation area of the excitation light L0 in the wavelength conversion member 3 can be moved along the X direction.

The drive unit 25 may include, for example, a motor as a drive source that generates a drive force to move the light source 2. The drive unit 25 may also include a power transmission mechanism such as a ball screw mechanism that transmits the drive force from the drive source to the light source 2.

Figure 20 is a diagram schematically illustrating an example of the arrangement of wavelength conversion members 3 and the irradiation region R1 of excitation light L0. The arrangement patterns of wavelength conversion members 3 in Figures 20(a) to 20(f) are the same as the arrangement patterns in Figures 9(a) to 9(f), respectively.

In Figure 20(a), the irradiation region R1 of the excitation light L0 is shown as a rectangle. The shape of the irradiation region R1 can be determined, for example, by placing one or more lenses between the light source 2 and the wavelength separation filter 4 and by the optical design of the lenses. In Figure 20(a), the irradiation region R1 spans the first wavelength conversion member 31 and the second wavelength conversion member 32 but is not located within the third wavelength conversion member 33. In this case, the lighting device 1B can emit fluorescence L1 that is a mixture of the first and second colors at a mixing ratio that corresponds to the area ratio of the first wavelength conversion member 31 and the second wavelength conversion member 32 within the irradiation region R1. By moving the irradiation region R1 along the X direction, the area of each wavelength conversion member 3 within the irradiation region R1 changes, thereby changing the color of the fluorescence L1. Note that in the example of Figure 20(a), the direction of movement of the irradiation region R1 is schematically indicated by a double-headed arrow.

The control unit 8 controls the light source 2 and the drive unit 25. For example, when the control unit 8 outputs a control signal to the drive unit 25 corresponding to a target value for the hue of the fluorescence L1, the drive unit 25 moves the light source 2 along the Z direction to a position based on the control signal. This causes the excitation light L0 from the light source 2 to be incident on the wavelength conversion member 3 in the irradiation region R1 corresponding to the target value for the hue of the fluorescence L1. Therefore, the lighting device 1B can emit fluorescence L1 that is close to the target hue into the illumination space S1.

20(b) and 20(c), the first wavelength conversion member 31 to the third wavelength conversion member 33 are positioned two-dimensionally in the XY plane. Therefore, the drive unit 25 may move the light source 2 two-dimensionally. For example, the drive unit 25 may move the light source 2 in the Y and Z directions, thereby moving the irradiation region R1 in the wavelength conversion member 3 in the X and Y directions. Note that in the examples of Figures 20(b) and 20(c), the movement direction of the irradiation region R1 is also schematically indicated by a double-headed arrow.

The drive unit 25 may include, for example, a first motor as an example of a drive source for the Y direction, and a second motor as an example of a drive source for the Z direction. The drive unit 25 may also include a power transmission mechanism for the Y direction, such as a ball screw mechanism, that transmits the drive force of the first motor to the light source 2, and a power transmission mechanism for the X direction, such as a ball screw mechanism, that transmits the drive force of the second motor to the light source 2.

20(d) and 20(e), the irradiation region R1 is shown as a circle. The diameter of the irradiation region R1 is smaller than the diameter of the circle of the structure including the first wavelength conversion member 31 to the third wavelength conversion member 33. The center of the irradiation region R1 is shifted from the center Q1 of the circle. In the examples of Figures 20(d) and 20(e), the irradiation region R1 spans the first wavelength conversion member 31 to the third wavelength conversion member 33. Therefore, the lighting device 1B can emit fluorescence L1, a mixture of the first to third colors, into the illumination space S1 at a mixing ratio according to the area ratio of the first wavelength conversion member 31 to the third wavelength conversion member 33 within the irradiation region R1.

As shown in Figures 20(d) and 20(e), the drive unit 25 may move the light source 2 so that the irradiation area R1 moves in the circumferential direction about the center Q1. Figure 21 is a diagram schematically showing an example of the configuration of such an illumination device 1B. The drive unit 25 moves the light source 2 in the circumferential direction about the central axis Q2. In other words, the drive unit 25 revolves the light source 2 around the central axis Q2. As shown in Figure 21, the drive unit 25 may include a drive source 251 such as a motor and an eccentric shaft 252. The eccentric shaft 252 is attached to the light source 2. The optical axis of the light source 2 is offset from the central axis Q2 in the Z direction. The central axis Q2 is a virtual axis that travels from the center Q1 along the Z direction to the -Z side and follows the virtual light ray reflected by the wavelength separation filter 4. The drive source 251 rotates the eccentric shaft 252 around the central axis Q2. As a result, the light source 2 revolves around the central axis Q2, and the irradiation region R1 revolves around the center Q1. This revolution changes the proportion of the area of each wavelength conversion member 3 in the irradiation region R1, and therefore the color of the fluorescence L1 can be changed.

In Figure 20(f), the irradiation area R1 of the excitation light L0 is shown as a rectangle. In Figure 20(f), the irradiation area R1 spans the first wavelength conversion member 31 and the second wavelength conversion member 32. In this case, the lighting device 1B can emit fluorescence L1 that is a mixture of colors of the first color temperature and the second color temperature at a mixing ratio that corresponds to the ratio of the areas of the first wavelength conversion member 31 and the second wavelength conversion member 32 within the irradiation area R1. By moving the irradiation area R1 along the X direction, the area of each wavelength conversion member 3 within the irradiation area R1 changes, and therefore the hue of the fluorescence L1 can be changed.

4. Fourth Embodiment
22 is a diagram schematically illustrating an example of an optical system of an illumination device 1C according to Embodiment 4. The illumination device 1C differs from the illumination device 1 according to Embodiment 1 in the shape of the wavelength conversion member 3.

As shown in FIG. 22, the surface 3b of the wavelength conversion member 3 may be non-flat. As a specific example, the surface 3b of the wavelength conversion member 3 may have a concave shape recessed toward the +Z side. In other words, the surface 3b of the wavelength conversion member 3 may have a concave shape in which the center of the surface 3b is farther from the wavelength separation filter 4 than the periphery of the surface 3b. The depth (or height) of the surface 3b may be, for example, approximately 1 mm or more. As shown in FIG. 22, the wavelength conversion member 3 may be positioned such that at least the center of the surface 3b faces the end face 5b of the light-guiding member 5 in the Z direction. In the example of FIG. 22, the surface 3b of the wavelength conversion member 3 has a semi-elliptical shape in a ZX cross section including the central axis of the light-guiding member 5. However, the shape of the surface 3b is not necessarily limited to this. For example, the surface 3b may have a semi-circular shape or a V-shape in a ZX cross section. The surface 3b may have a shape in the ZX cross section that extends uniformly along the Y direction, or may have, for example, a hemispherical, semi-ellipsoidal, conical or pyramidal shape. Also, as shown in Fig. 22 , the surface 3a of the wavelength conversion member 3 may have the same or similar shape as the surface 3b.

In the lighting device 1C, the surface area of the surface 3b of the wavelength conversion member 3 is relatively large. This allows the excitation light L0 to be incident on a wider irradiation area of the surface 3b of the wavelength conversion member 3. This reduces the power density of the excitation light L0 on the surface 3b, thereby reducing the temperature rise of the wavelength conversion member 3. This reduces the degree of thermal degradation of the wavelength conversion member 3.

In addition, in the example of Figure 22, the surface 3b of the wavelength conversion member 3 has a concave shape that is recessed toward the +Z side. This shape allows more of the fluorescence L1 emitted by the wavelength conversion member 3 to travel toward the center of the end face 5b of the light-guiding member 5. This makes it possible to improve the amount of fluorescence L1 incident on the wavelength separation filter 4. As a result, the lighting device 1C can emit fluorescence L1 into the illumination space S1 with higher efficiency.

Figure 23 is a diagram schematically illustrating another example of the shape of the wavelength conversion member 3. As shown in Figure 23(a), the surface 3b of the wavelength conversion member 3 may have an uneven shape. That is, the surface 3b of the wavelength conversion member 3 may have an uneven shape in a ZX cross section including the central axis of the cylindrical surface 5a. In the example of Figure 23(a), the surface 3b of the wavelength conversion member 3 has a linear uneven shape in the ZX cross section, but it may also have a curved uneven shape. That is, each concave portion of the uneven shape of the surface 3b may have a V-shape, or may have a semicircular or semi-elliptical shape. Furthermore, multiple concave portions in the uneven shape may be arranged one-dimensionally or two-dimensionally. That is, multiple concave portions may be arranged one-dimensionally in the X direction or Y direction, or may be arranged two-dimensionally in the XY plane. When multiple concave portions are arranged one-dimensionally, each concave portion of the uneven shape of the surface 3b may have a ZX cross section that extends uniformly along the Y direction, for example. When multiple recesses are arranged two-dimensionally, each recess in the uneven shape of the surface 3b may have, for example, a hemispherical, semi-ellipsoidal, conical, or pyramidal shape. The depth (or height) of each recess in the uneven shape of the surface 3b may be, for example, about 1 mm or more. The wavelength conversion member 3 is positioned such that at least one recess in the surface 3b faces the end face 5b of the light-guiding member 5 in the Z direction.

As shown in Figure 23 (b), the surface 3b of the wavelength conversion member 3 may have a convex shape that bulges toward the -Z side. In other words, the surface 3b of the wavelength conversion member 3 has a convex shape in which the center of the surface 3b is closer to the wavelength separation filter 4 than the periphery of the surface 3b. The height of the surface 3b may be, for example, approximately 1 mm or more. The wavelength conversion member 3 is positioned such that at least the center of the surface 3b faces the end surface 5b of the light-guiding member 5 in the Z direction.

In all of the wavelength conversion members 3 shown in Figure 23, the surface 3b is non-planar, so the surface area of the surface 3b onto which the excitation light L0 is incident is large. This reduces the temperature rise of the wavelength conversion member 3 and reduces the degree of thermal degradation of the wavelength conversion member 3.

<4-1. Alternative embodiments>
Fig. 24 is a diagram schematically illustrating another aspect of the optical system of the illumination device 1C according to the fourth embodiment. The illumination device 1C according to the other aspect of the fourth embodiment differs from the illumination device 1C in Fig. 22 in the configuration of the wavelength conversion member 3.

In the example of Figure 24, multiple wavelength conversion members 3 are shown, including a first wavelength conversion member 31 to a third wavelength conversion member 33 that are the same as or similar to those in Figure 10. In the example of Figure 24, the first wavelength conversion member 31, the second wavelength conversion member 32, and the third wavelength conversion member 33 are arranged in this order in the X direction. The first wavelength conversion member 31 may be in contact with the second wavelength conversion member 32, and the second wavelength conversion member 32 may be in contact with the third wavelength conversion member 33.

As shown in Figure 24, the surfaces 3b of the first wavelength conversion member 31 to the third wavelength conversion member 33 are non-planar and have a concave shape that is recessed toward the +Z side as a whole. In other words, the concave surface is formed by the surfaces 3b of the first wavelength conversion member 31 to the third wavelength conversion member 33. The first wavelength conversion member 31 to the third wavelength conversion member 33 in Figure 24 may each correspond to a portion obtained by dividing the wavelength conversion member 3 in Figure 22 into three in the X direction. The surfaces 3b of the first wavelength conversion member 31 to the third wavelength conversion member 33 face the end face 5b of the light-guiding member 5 in the Z direction.

As shown in Figure 24, the lighting device 1C may have multiple light sources 2 corresponding to multiple wavelength conversion members 3. In the example of Figure 24, the multiple light sources 2 shown are a first light source 21 to a third light source 23 that are the same as or similar to those in Figure 10.

According to the fourth embodiment, the entire surfaces 3b of the first wavelength conversion member 31 to the third wavelength conversion member 33 are non-planar. This reduces the temperature rise of the first wavelength conversion member 31 to the third wavelength conversion member 33. In addition, in the example of FIG. 24, the entire surfaces 3b of the first wavelength conversion member 31 to the third wavelength conversion member 33 have a concave shape recessed toward the +Z side. This allows more of the fluorescence L1 emitted by each of the first wavelength conversion member 31 to the third wavelength conversion member 33 to be incident on the end surface 5b of the light-guiding member 5.

25(a) and 25(b) are diagrams schematically illustrating other examples of the shape of the wavelength conversion member 3. As shown in FIGS. 25(a) and 25(b), each of the surfaces 3b of the first to third wavelength conversion members 31 to 33 may have a single concave shape. In the examples of FIGS. 25(a) and 25(b), the first to third wavelength conversion members 31 to 33 are aligned in the X direction, so the entire surfaces 3b of the first to third wavelength conversion members 31 to 33 have an uneven shape. As an example of the shape of each surface 3b, as shown in FIG. 25(a), it may have a semi-elliptical or semi-circular shape in the ZX cross section, or as shown in FIG. 25(b), it may have a V-shape in the ZX cross section. Each surface 3b may have a shape in the ZX cross section that extends uniformly along the Y direction, or may have a hemispherical, semi-elliptical, conical, or pyramidal shape, for example.

As shown in Figure 25(c), each of the surfaces 3b of the first wavelength conversion member 31 to the third wavelength conversion member 33 may have an uneven shape. Examples of the uneven shape on each surface 3b are the same as or similar to those shown in Figure 23(a).

Furthermore, each of the surfaces 3b of the first wavelength conversion member 31 to the third wavelength conversion member 33 may have a single convex shape that bulges toward the +Z side. Examples of the convex shape on each surface 3b are the same as or similar to those shown in Figure 23(b).

The first wavelength conversion member 31 to the third wavelength conversion member 33 may have the same shape. This allows the first wavelength conversion member 31 to the third wavelength conversion member 33 to emit fluorescence L1 to the same extent. Therefore, the lighting device 1C can emit fluorescence L1 with less color unevenness into the lighting space S1.

As mentioned above, the lighting devices 1, 1A-1C have been described in detail. However, the above description is merely an example in all respects, and the lighting devices 1, 1A-1C are not limited thereto. It is understood that countless variations not illustrated can be envisioned without departing from the scope of this disclosure. The configurations described in the above embodiments and variations (or aspects) can be combined or omitted as appropriate, as long as they are not mutually inconsistent.

It goes without saying that all or part of the components of each of the above-mentioned embodiments and various modified examples (or aspects) can be combined as appropriate and consistent.

This disclosure includes the following:

In one embodiment, (1) the lighting device comprises one or more light sources that emit excitation light; one or more wavelength conversion elements that receive the excitation light from the light sources and emit fluorescence based on the excitation light, the fluorescence having a spectrum different from that of the excitation light; one or more wavelength separation filters that guide the excitation light from the light sources to the wavelength conversion elements and receive the fluorescence from the wavelength conversion elements; a light-guiding element that has a cylindrical surface and through which the fluorescence from the wavelength separation filters travels within an area surrounded by the cylindrical surface while repeatedly reflecting off the cylindrical surface; and a lens optical system that includes a lens on which the fluorescence emitted from the light-guiding element is incident and forms an image of the emission surface of the light-guiding element on a virtual image plane.

(2) In the lighting device of (1) above, the wavelength separation filter may include a dielectric multilayer film that reflects one of the excitation light and the fluorescence and transmits the other of the excitation light and the fluorescence, and the light-guiding member may include a first transparent member having a first inclined surface on which the dielectric multilayer film is located, the exit surface on the lens optical system side, and a first side surface that is at least a part of the cylindrical surface that connects the periphery of the first inclined surface and the periphery of the exit surface.

(3) In the lighting device of (2) above, the light-guiding member may further include a second transparent member, which has a second inclined surface that sandwiches the dielectric multilayer film together with the first inclined surface of the first transparent member, an end face opposite the second inclined surface, and a second side surface that connects the second inclined surface and the end face.

(4) In the lighting device of (1) above, the light-guiding member may include a rod lens located away from the wavelength separation filter and having an end surface onto which the fluorescence from the wavelength separation filter is incident, an exit surface on the lens optical system side, and a side surface which is the cylindrical surface connecting the end surface and the exit surface.

(5) In the lighting device described in (4) above, the wavelength separation filter may include a dichroic prism having a dielectric multilayer film that reflects one of the excitation light and the fluorescence and transmits the other of the excitation light and the fluorescence.

(6) In the lighting device of (4) above, the wavelength separation filter may include a plate-shaped transparent substrate having a first surface and a second surface, and a dielectric multilayer film located on the first surface or the second surface of the transparent substrate, which reflects one of the excitation light and the fluorescent light and transmits the other of the excitation light and the fluorescent light.

(7) In any one of the lighting devices (1) to (6) above, the one or more wavelength conversion members may include a first wavelength conversion member and a second wavelength conversion member that emit the fluorescence of different spectra from each other.

(8) In the lighting device of (7) above, the one or more light sources may include a first light source that emits the excitation light toward the first wavelength conversion member and a second light source that emits the excitation light toward the second wavelength conversion member.

(9) In the lighting device of (8) above, the first wavelength conversion member and the second wavelength conversion member can be adjacent to each other, and the one or more wavelength separation filters can include a single wavelength separation filter, which can guide the excitation light from the first light source to the first wavelength conversion member, can guide the excitation light from the second light source to the second wavelength conversion member, and can guide the fluorescence from the first wavelength conversion member and the second wavelength conversion member to the light-guiding member.

(10) In the lighting device of (8) above, the one or more wavelength separation filters may include a first wavelength separation filter that guides the excitation light from the first light source to the first wavelength conversion member and onto which the fluorescence from the first wavelength conversion member is incident, and a second wavelength separation filter that guides the excitation light from the second light source to the second wavelength conversion member and onto which the fluorescence from the second wavelength conversion member is incident.

(11) In the lighting device of (10) above, the first peak wavelength of the fluorescence emitted by the first wavelength conversion member may be longer than the second peak wavelength of the fluorescence emitted by the second wavelength conversion member, and the second peak wavelength may be longer than the excitation peak wavelength of the excitation light, the second wavelength separation filter may guide the fluorescence from the second wavelength conversion member to the first wavelength separation filter, and the first wavelength separation filter may combine the fluorescence from the first wavelength conversion member and the fluorescence from the second wavelength separation filter and guide the combined fluorescence to the light-guiding member.

(12) In the lighting device of (11) above, the one or more wavelength conversion members may further include a third wavelength conversion member that emits the fluorescence having a third peak wavelength that is shorter than the second peak wavelength and longer than the excitation peak wavelength, the one or more light sources may further include a third light source that emits the excitation light for the third wavelength conversion member, and the one or more wavelength separation filters may further include a third wavelength separation filter that guides the excitation light from the third light source to the third wavelength conversion member and guides the fluorescence from the third wavelength conversion member to the second wavelength separation filter, The long separation filter can combine the fluorescence from the third wavelength separation filter and the fluorescence from the second wavelength conversion member and guide the combined fluorescence to the first wavelength separation filter, and the cutoff wavelength of the first wavelength separation filter can be set to a value between the first peak wavelength and the second peak wavelength, the cutoff wavelength of the second wavelength separation filter can be set to a value between the second peak wavelength and the third peak wavelength, and the cutoff wavelength of the third wavelength separation filter can be set to a value between the third peak wavelength and the excitation peak wavelength.

(13) In the lighting device of (11) or (12) above, the first wavelength conversion member can be aligned with the first wavelength separation filter in a first direction and can be positioned on a first side relative to the first wavelength separation filter, the second wavelength conversion member can be aligned with the second wavelength separation filter in the first direction and can be positioned on the first side relative to the second wavelength separation filter, and the first wavelength separation filter can be aligned with the second wavelength separation filter in a second direction intersecting the first direction.

(14) The lighting device of (13) above may further include a cooling member that supports both the first wavelength conversion member and the second wavelength conversion member and has a thermal conductivity higher than that of both the first wavelength conversion member and the second wavelength conversion member.

(15) In the lighting device of (11) or (12) above, the first wavelength conversion member can be aligned with the first wavelength separation filter in a first direction and can be positioned on a first side relative to the first wavelength separation filter, the second wavelength conversion member can be aligned with the second wavelength separation filter in the first direction and can be positioned on a second side opposite to the first side relative to the second wavelength separation filter, and the first wavelength separation filter can be aligned with the second wavelength separation filter in a second direction intersecting the first direction.

(16) In any one of the lighting devices (13) to (15) above, the first wavelength separation filter, the second wavelength separation filter, and the light-guiding member can be aligned in the second direction.

(17) In the lighting device of (11) or (12) above, the first wavelength separation filter and the second wavelength separation filter can be aligned in a first direction, and the first wavelength separation filter and the light-guiding member can be aligned in a second direction intersecting the first direction.

(18) In the lighting device of (17) above, the one or more wavelength conversion members may further include a third wavelength conversion member, and the third wavelength conversion member may emit fluorescence having a peak wavelength shorter than the peak wavelength of the fluorescence emitted by the second wavelength conversion member and longer than the peak wavelength of the excitation light, the one or more light sources may further include a third light source that emits the excitation light to the third wavelength conversion member, the one or more wavelength separation filters may further include a third wavelength separation filter that guides the excitation light from the third light source to the third wavelength conversion member and guides the fluorescence from the third wavelength conversion member to the second wavelength separation filter, and the second wavelength separation filter may guide the fluorescence from the third wavelength separation filter to the second wavelength separation filter, and the third wavelength separation filter may face the second wavelength separation filter in the second direction and be located on the light-guiding member side of the second wavelength separation filter.

(19) Any one of the lighting devices (10) to (18) above may further include a transparent member positioned between the dielectric multilayer film of the first wavelength separation filter and the dielectric multilayer film of the second wavelength separation filter, supporting the dielectric multilayer film of the first wavelength separation filter and the dielectric multilayer film of the second wavelength separation filter.

(20) The lighting device of (10) above may further include a converging element into which the fluorescence from the first wavelength separation filter and the fluorescence from the second wavelength separation filter are incident from different directions, and the converging element can converge the fluorescence from the first wavelength separation filter and the fluorescence from the second wavelength separation filter and guide the converged fluorescence to the light-guiding member.

(21) The lighting device of (7) above may further include a drive unit that displaces the light source, the first wavelength conversion member and the second wavelength conversion member may be adjacent to each other, the wavelength separation filter may guide the excitation light from the light source to the first wavelength conversion member and the second wavelength conversion member, and the drive unit may displace the light source and move the irradiation area of the excitation light relative to the first wavelength conversion member and the second wavelength conversion member.

(22) In any one of the lighting devices (1) to (21) above, the surface of the wavelength conversion member facing the wavelength separation filter may have a convex, concave, or uneven shape.

REFERENCE SIGNS LIST 1 Illumination device 2 Light source 21 First light source 22 Second light source 3 Wavelength conversion member 31 First wavelength conversion member 32 Second wavelength conversion member 3b Surface 4 Wavelength separation filter 41 First wavelength separation filter 42 Second wavelength separation filter 412 Transparent member (second transparent member)
5 Light guide member 51 First transparent member 52 Second transparent member 6 Lens optical system 61 Lens 7 Housing 7a Opening

Claims (20)

one or more light sources that emit excitation light;
one or more wavelength converting members that receive the excitation light from the light source and emit fluorescence having a spectrum different from that of the excitation light based on the excitation light;
one or more wavelength separation filters that guide the excitation light from the light source to the wavelength conversion member and onto which the fluorescence from the wavelength conversion member is incident;
a light guiding member having a cylindrical surface, wherein the fluorescence from the wavelength separation filter travels through an interior surrounded by the cylindrical surface while being repeatedly reflected by the cylindrical surface;
a lens optical system including a lens onto which the fluorescence emitted from the light guiding member is incident, and which forms an image of the emission surface of the light guiding member on a virtual image plane ,
the one or more wavelength converting members include a first wavelength converting member and a second wavelength converting member that emit the fluorescence having different spectra from each other;
The one or more light sources
a first light source that emits the excitation light toward the first wavelength conversion member;
a second light source that emits the excitation light toward the second wavelength conversion member;
1. A lighting device comprising : 10. The lighting device according to claim 1,
the wavelength separation filter includes a dielectric multilayer film that reflects one of the excitation light and the fluorescent light and transmits the other of the excitation light and the fluorescent light;
The light guide member is
an illumination device comprising a first transparent member having a first inclined surface on which the dielectric multilayer film is located, an exit surface on the lens optical system side, and a first side surface that is at least a part of the cylindrical surface that connects the periphery of the first inclined surface and the periphery of the exit surface. 3. The lighting device according to claim 2,
the light-guiding member further includes a second transparent member;
The second transparent member is
a second inclined surface that sandwiches the dielectric multilayer film together with the first inclined surface of the first transparent member;
an end surface opposite to the second inclined surface;
a second side surface connecting the second inclined surface and the end surface; 10. The lighting device according to claim 1,
The light guide member is
an end surface positioned away from the wavelength separation filter, on which the fluorescence from the wavelength separation filter is incident;
an exit surface on the lens optical system side;
An illumination device comprising a rod lens having a side surface that is the cylindrical surface and connects the end surface and the light exit surface. 5. The lighting device according to claim 4,
The wavelength separation filter is
an illumination device comprising: a dichroic prism having a dielectric multilayer film that reflects one of the excitation light and the fluorescent light and transmits the other of the excitation light and the fluorescent light; 5. The lighting device according to claim 4,
The wavelength separation filter is
a plate-shaped transparent substrate having a first surface and a second surface;
a dielectric multilayer film located on the first surface or the second surface of the transparent base material, the dielectric multilayer film reflecting one of the excitation light and the fluorescent light and transmitting the other of the excitation light and the fluorescent light. 7. The lighting device according to claim 1 ,
the first wavelength converting member and the second wavelength converting member are adjacent to each other,
the one or more wavelength separation filters include a single wavelength separation filter;
the single wavelength separation filter guides the excitation light from the first light source to the first wavelength conversion member, guides the excitation light from the second light source to the second wavelength conversion member, and guides the fluorescence from the first wavelength conversion member and the second wavelength conversion member to the light-guiding member. 7. The lighting device according to claim 1 ,
The one or more wavelength separation filters are
a first wavelength separation filter that guides the excitation light from the first light source to the first wavelength conversion member and onto which the fluorescence from the first wavelength conversion member is incident;
a second wavelength separation filter that guides the excitation light from the second light source to the second wavelength conversion member and onto which the fluorescence from the second wavelength conversion member is incident. 9. The lighting device according to claim 8 ,
a first peak wavelength of the fluorescence emitted by the first wavelength converting member is longer than a second peak wavelength of the fluorescence emitted by the second wavelength converting member;
the second peak wavelength is longer than the excitation peak wavelength of the excitation light,
the second wavelength separation filter guides the fluorescence from the second wavelength conversion member to the first wavelength separation filter;
The first wavelength separation filter combines the fluorescence from the first wavelength conversion member and the fluorescence from the second wavelength separation filter, and guides the combined fluorescence to the light guiding member. 10. The lighting device according to claim 9 ,
the one or more wavelength converting members further include a third wavelength converting member that emits the fluorescence having a third peak wavelength that is shorter than the second peak wavelength and longer than the excitation peak wavelength,
the one or more light sources further include a third light source that emits the excitation light toward the third wavelength conversion member,
the one or more wavelength separation filters further include a third wavelength separation filter that guides the excitation light from the third light source to the third wavelength converting member and guides the fluorescence from the third wavelength converting member to the second wavelength separation filter,
the second wavelength separation filter combines the fluorescence from the third wavelength separation filter and the fluorescence from the second wavelength conversion member and guides the combined fluorescence to the first wavelength separation filter;
a cutoff wavelength of the first wavelength separation filter is set to a value between the first peak wavelength and the second peak wavelength,
a cutoff wavelength of the second wavelength separation filter is set to a value between the second peak wavelength and the third peak wavelength,
an illumination device, wherein the cutoff wavelength of the third wavelength separation filter is set to a value between the third peak wavelength and the excitation peak wavelength. 10. The lighting device according to claim 9 ,
the first wavelength conversion member is aligned with the first wavelength separation filter in a first direction and is located on a first side with respect to the first wavelength separation filter;
the second wavelength conversion member is aligned with the second wavelength separation filter in the first direction and is located on the first side with respect to the second wavelength separation filter,
The illumination device, wherein the first wavelength separation filter is aligned with the second wavelength separation filter in a second direction that intersects with the first direction. 12. The lighting device according to claim 11 ,
a cooling member that supports both the first wavelength conversion member and the second wavelength conversion member and has a thermal conductivity higher than that of both the first wavelength conversion member and the second wavelength conversion member. 10. The lighting device according to claim 9 ,
the first wavelength conversion member is aligned with the first wavelength separation filter in a first direction and is located on a first side with respect to the first wavelength separation filter;
the second wavelength conversion member is aligned with the second wavelength separation filter in the first direction and is located on a second side opposite to the first side with respect to the second wavelength separation filter,
The illumination device, wherein the first wavelength separation filter is aligned with the second wavelength separation filter in a second direction that intersects with the first direction. 12. The lighting device according to claim 11 ,
The first wavelength separation filter, the second wavelength separation filter, and the light guiding member are aligned in the second direction. 10. The lighting device according to claim 9 ,
the first wavelength separation filter and the second wavelength separation filter are aligned in a first direction,
The illumination device, wherein the first wavelength separation filter and the light guiding member are aligned in a second direction intersecting the first direction. 16. The lighting device according to claim 15 ,
the one or more wavelength converting members further include a third wavelength converting member;
the third wavelength converting member emits the fluorescence having a peak wavelength that is shorter than the peak wavelength of the fluorescence emitted by the second wavelength converting member and longer than the peak wavelength of the excitation light,
the one or more light sources further include a third light source that emits the excitation light toward the third wavelength conversion member,
the one or more wavelength separation filters further include a third wavelength separation filter that guides the excitation light from the third light source to the third wavelength converting member and guides the fluorescence from the third wavelength converting member to the second wavelength separation filter,
the second wavelength separation filter guides the fluorescence from the third wavelength separation filter to the second wavelength separation filter;
the third wavelength separation filter faces the second wavelength separation filter in the second direction and is located on the light-guiding member side of the second wavelength separation filter. 9. The lighting device according to claim 8 ,
the illumination device further comprising a transparent member positioned between the dielectric multilayer film of the first wavelength separation filter and the dielectric multilayer film of the second wavelength separation filter, the transparent member supporting the dielectric multilayer film of the first wavelength separation filter and the dielectric multilayer film of the second wavelength separation filter. 9. The lighting device according to claim 8 ,
a combining element onto which the fluorescence from the first wavelength separation filter and the fluorescence from the second wavelength separation filter are incident from different directions,
The combining element combines the fluorescence from the first wavelength separation filter and the fluorescence from the second wavelength separation filter, and guides the combined fluorescence to the light-guiding member. one or more light sources that emit excitation light;
one or more wavelength converting members that receive the excitation light from the light source and emit fluorescence having a spectrum different from that of the excitation light based on the excitation light;
one or more wavelength separation filters that guide the excitation light from the light source to the wavelength conversion member and onto which the fluorescence from the wavelength conversion member is incident;
a light guiding member having a cylindrical surface, wherein the fluorescence from the wavelength separation filter travels through an interior surrounded by the cylindrical surface while being repeatedly reflected by the cylindrical surface;
a lens optical system including a lens onto which the fluorescence emitted from the light guiding member is incident, the lens optical system forming an image of an exit surface of the light guiding member on a virtual image plane;
a driving unit that displaces the light source ;
Equipped with
the one or more wavelength converting members include a first wavelength converting member and a second wavelength converting member that emit the fluorescence having different spectra from each other;
the first wavelength converting member and the second wavelength converting member are adjacent to each other,
the wavelength separation filter guides the excitation light from the light source to the first wavelength conversion member and the second wavelength conversion member;
The driving unit displaces the light source to move an irradiation area of the excitation light with respect to the first wavelength conversion member and the second wavelength conversion member. 20. The lighting device according to claim 1, wherein:
The illumination device, wherein the surface of the wavelength conversion member on the wavelength separation filter side has a convex, concave, or uneven shape.