JP7249550B2 - lighting equipment - Google Patents

Description

The present disclosure relates to a lighting device using laser light.

For example, Patent Document 1 discloses an example of an illumination device, which includes an optical fiber that guides laser light emitted from a laser light source, and a wavelength conversion member that converts the wavelength of the laser light guided through the optical fiber. is disclosed.

WO2017/043122

However, in the above-described conventional optical fiber, it is difficult to make the emitted light uniform when the cross-sectional shape of the core is circular. This is probably because the laser light is not sufficiently mixed when passing through the optical fiber, but processing the cross-sectional shape of the optical fiber for mixing increases the manufacturing cost. Therefore, it is difficult to use for lighting.

Therefore, it is an object of the present invention to provide a lighting device capable of stabilizing chromaticity while suppressing an increase in manufacturing cost.

To achieve the above object, an illumination device according to an aspect of the present disclosure includes a laser light source that emits laser light, an optical fiber that guides the laser light, and the laser light that is guided to the optical fiber. A kaleidoscope that includes a transmission line for transmission, and a wavelength conversion element that emits wavelength-converted light by the laser light emitted from the transmission line, wherein the kaleidoscope is connected to the optical fiber. When the transmission line is arranged between the wavelength conversion element and is cut along a plane orthogonal to the direction in which the laser light is transmitted, the cross section of the transmission line is polygonal, and the kaleidoscope is configured to An opening at one end of the kaleidoscope into which the laser beam guided to the optical fiber is incident, and an opening at the other end of the kaleidoscope from which the laser beam guided to the optical fiber is emitted, A wavelength conversion element is arranged to cover the opening at the other end of the kaleidoscope .

The lighting device according to the present disclosure can suppress an increase in manufacturing cost and stabilize chromaticity.

FIG. 1 is a perspective view of a lighting device according to an embodiment. FIG. 2 is a schematic diagram illustrating an excitation light source in the lighting device according to the embodiment, and is a cross-sectional view illustrating the lighting fixture and the like taken along line II-II in FIG. 3A is a partially enlarged cross-sectional view illustrating an optical fiber, a ferrule, a diffusion plate, a kaleidoscope, a wavelength conversion element, etc. of the illumination device according to the embodiment; FIG. FIG. 3B is a partially enlarged cross-sectional view illustrating an optical fiber, a ferrule, a kaleidoscope, a wavelength conversion element, etc. of an illumination device according to another modification. FIG. 3C is a partially enlarged cross-sectional view illustrating an optical fiber, a kaleidoscope, a wavelength conversion element, etc. of an illumination device according to another modification. FIG. 3D is a partially enlarged cross-sectional view illustrating an optical fiber, a kaleidoscope, a wavelength conversion element, etc. of an illumination device according to another modification. FIG. 3E is a partially enlarged cross-sectional view illustrating a plurality of optical fibers, a kaleidoscope, a wavelength conversion element, etc. of an illumination device according to another modification. FIG. 3F is a diagram showing the luminance distribution of each of the laser beams emitted from the plurality of optical fibers of the illumination device according to another modification, and FIG. It is a figure which shows luminance distribution. FIG. 4 is a diagram showing the light color on the chromaticity coordinates of the light emitted from the lighting device according to the embodiment, and a diagram showing the light color on the chromaticity coordinates of the light emitted from the lighting device according to the comparative example. be. 5A is a diagram illustrating a luminance distribution of light emitted from a wavelength conversion element of the lighting device according to the embodiment; FIG. FIG. 5B is a diagram different from FIG. 5A exemplifying the luminance distribution of light emitted from the wavelength conversion element of the lighting device according to the embodiment. FIG. 6 is a diagram showing the relationship between the length of the kaleidoscope of the lighting device according to the embodiment and the amount of chromaticity change. 7A and 7B are diagrams illustrating a radiance distribution when light emitted from the kaleidoscope of the lighting device according to the embodiment is irradiated onto an irradiation surface, and a relationship between the cross-sectional shape of the kaleidoscope and the uniformity of light; It is a figure which illustrates. FIG. 8A is a diagram illustrating a luminance distribution of light emitted from a wavelength conversion element of an illumination device according to a comparative example; FIG. 8B is a diagram different from FIG. 8A exemplifying the luminance distribution of light emitted from the wavelength conversion element of the lighting device according to the comparative example. FIG. 9A is a schematic diagram illustrating a laser light source according to a comparative example used to illustrate the luminance distribution of FIG. 8A. FIG. 9B is a schematic diagram illustrating a laser light source according to a comparative example used to illustrate the luminance distribution of FIG. 8B.

Embodiments of the present disclosure will be described below with reference to the drawings. It should be noted that each of the embodiments described below is a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, etc. shown in the following embodiments are examples and are not intended to limit the present disclosure. do not have. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in independent claims representing the highest concept of the present disclosure will be described as optional constituent elements.

Each figure is a schematic diagram and is not necessarily strictly illustrated. Therefore, for example, the scales and the like do not necessarily match in each drawing. Moreover, in each figure, the same code|symbol is attached|subjected to the substantially same structure, and the overlapping description is abbreviate|omitted or simplified.

Moreover, in the following embodiments, expressions such as substantially parallel are used. For example, "substantially orthogonal" means not only completely orthogonal, but also substantially orthogonal, that is, including an error of, for example, several percent. Also, substantially orthogonal means orthogonal within the range where the effects of the present disclosure can be achieved. The same applies to expressions using other "abbreviations".

A lighting device according to the following embodiments will be described.

(Embodiment)
[composition]
[Lighting device 1]
FIG. 1 is a perspective view of a lighting device 1 according to an embodiment. FIG. 2 is a schematic diagram illustrating the excitation light source 3 in the illumination device 1 according to the embodiment, and is a cross-sectional view illustrating the lamp fixture 5 and the like taken along line II-II in FIG.

As shown in FIGS. 1 and 2, the illumination device 1 is a reflective illumination device using laser light, and includes an excitation light source 3, a plurality of optical fibers 11, a ferrule 12, a diffusion plate 20, and a kaleidoscope. A scope 30 and a lamp 5 are provided. The illumination device 1 is used, for example, as a downlight, a spotlight, or the like. Here, the reflective illumination device 1 using laser light is such that the rear surface of the fluorescent unit 40 (the surface on the kaleidoscope 30 side) is irradiated with the laser light, and wavelength-converted light (fluorescence) whose wavelength is converted is emitted. , is a device delivered from the front of the fluorescent unit 40 .

[Excitation light source 3]
The excitation light source 3 is a device that includes one or more laser elements and emits laser light. In this embodiment, the excitation light source 3 includes two or more laser elements. The excitation light source 3 has, for example, a container 81, a laser light source 83, a plurality of prisms 85, a plurality of lenses 87, a ferrule 88, a heat sink 89, and a drive circuit 91, as shown in FIG.

<Container 81>
The container 81 is a housing portion of the excitation light source 3 shown in FIG. The container 81 contains a plurality of laser light sources 83, a prism 85, a lens 87, a ferrule 88, a heat sink 89, and a drive circuit 91, as shown in FIG.

<Laser light source 83>
Each of the plurality of laser light sources 83 includes a semiconductor light emitting element lens and emits substantially collimated laser light. A plurality of laser light sources 83 are mounted on a substrate and thermally connected to a heat sink 89 via the substrate. In the example shown in FIG. 2, some of the plurality of laser light sources 83 are grouped together. A set of laser light sources 83 causes the laser light to be incident on the incident surface, which is one end surface of the optical fiber 11 , by inputting the laser light into the prism 85 . Although a plurality of laser light sources 83 are used in this embodiment, only one laser light source 83 may be used. In the present embodiment, the laser light emitted by the laser light source 83 is light of a predetermined wavelength in the wavelength band from violet to blue.

Moreover, although one set of laser light sources 83 is used in this embodiment, a plurality of sets of laser light sources 83 may be used. In this case, the number of prisms 85 , lenses 87 and ferrules 88 corresponding to one set of laser light sources 83 is provided.

The laser light source 83 is composed of a semiconductor laser, for example, an InGaN laser diode. A semiconductor laser or an LED (Light Emitting Diode) with a wavelength of .

The power of the laser light emitted by the laser light source 83 is controlled by the drive circuit 91 . Also, the laser light source 83 may include a laser that emits laser light in a wavelength band that does not excite the wavelength conversion element 41 of the fluorescent portion 40 .

<Prism 85>
The prism 85 is a translucent plate-like member. The prism 85 causes the laser light emitted from the pair of laser light sources 83 to enter the lens 87 .

The prism 85 is arranged so as to be perpendicular to the optical axis of the laser light emitted by the laser light source 83 , that is, arranged so as to face the pair of laser light sources 83 .

Thus, the prism 85 has the function of a light guide that guides the laser beams emitted by the set of laser light sources 83 to the lens 87 . It should be noted that this configuration can also be replaced with two pairs of mirrors.

<Lens 87>
The lenses 87 are arranged so as to face the prisms 85 on a one-to-one basis. The lens 87 converges the laser light emitted from the prism 85 and causes it to enter one end surface of the optical fiber 11 . Although the lens 87 is a convex lens in the example shown in FIG. 2, it may be an optical device capable of condensing laser light and making it incident on one end surface of the optical fiber 11. For example, it may be a concave mirror. good too.

<Ferrule 88>
The ferrule 88 is fixed to the container 81 and holds one end of the corresponding optical fiber 11 . That is, the ferrule 88 holds one end of the optical fiber 11 so that the laser light emitted from the lens 87 is incident on the optical fiber 11 .

<Heat sink 89>
The heat sink 89 is a heat dissipation member for dissipating heat generated in the plurality of laser light sources 83, and has a plurality of fins. Also, the heat sink 89 fixes the substrate on which the laser light source 83 is mounted.

<Drive circuit 91>
The drive circuit 91 is electrically connected to a power system via a power line or the like, and supplies power to each laser light source 83 . Further, the drive circuit 91 drives and controls the output of each laser light source 83 so that each laser light source 83 emits a predetermined laser beam.

The drive circuit 91 may have a function of adjusting the laser light emitted by each laser light source 83 . Further, the drive circuit 91 may be composed of an oscillator or the like that drives the laser light source 83 based on the pulse signal.

Next, the configuration of the optical fiber 11, the kaleidoscope 30, etc. will be described with reference to FIG. 3A. FIG. 3A is a partially enlarged cross-sectional view illustrating the optical fiber 11, ferrule 12, diffusion plate 20, kaleidoscope 30, fluorescent section 40, etc. of the illumination device 1 according to the embodiment.

[Optical fiber 11]
As shown in FIGS. 2 and 3A, the optical fiber 11 is, for example, a transmission body composed of a double structure in which a core with a high refractive index is wrapped by a cladding layer with a lower refractive index than the core. It is made of a material such as plastic. The optical fiber 11 transmits laser light emitted from the laser light source 83 . In this embodiment, there are two or more optical fibers 11, and the laser beams emitted from the corresponding laser elements of the two or more laser light sources 83 are transmitted. In the example shown in FIG. 2, the optical fibers 11 consist of four. A laser beam emitted by the excitation light source 3 is incident on one end of the optical fiber 11 , and a laser beam emitted by the excitation light source 3 is emitted from the other end of the optical fiber 11 .

It is assumed that one end of the optical fiber 11 is upstream of the optical path along which the laser light is transmitted, and the other end is downstream of the optical path along which the laser light is transmitted.

As shown in FIG. 3A, the optical fiber 11 has an emission surface 11a from which guided laser light is emitted. The exit surface 11 a is the other end of the optical fiber 11 . The exit surface 11 a faces the diffusion plate 20 with the ferrule 12 interposed therebetween. The exit surface 11a is a substantially mirror surface, that is, a substantially flat surface. The rough surface of the output surface 11 a may be formed by polishing, for example, or by cleaving the optical fiber 11 . A rough surface may be formed on the output surface 11a. Also, a structure may be formed to reduce light loss at the end face. Structures for reducing light loss include, for example, AR coating with a dielectric film and imprint processing. Note that the dielectric film is preferably an inorganic film from the viewpoint of laser resistance.

[Ferrule 12]
A ferrule 12 holds the other end of the optical fiber 11 . Specifically, the ferrule 12 holds the other end of the optical fiber 11 so that the laser light emitted from the emission surface 11a of the optical fiber 11 is incident on the kaleidoscope 30 via the diffusion plate 20. . Here, the optical axis of the ferrule 12 is a straight line that coincides with the main light emitting direction, and roughly coincides with the central axis O.

[Diffusion plate 20]
The diffusing plate 20 is a plate-like optical member arranged on the central axis O and between the optical fiber 11 and the kaleidoscope 30 to diffuse and transmit the laser light guided by the optical fiber 11 . The diffuser plate 20 has an incident surface on which the laser light is incident and an output surface opposite to the incident surface from which the diffused and transmitted laser light is emitted.

The incident surface of the diffuser plate 20 faces the ferrule 12 provided at the tip of the optical fiber 11 and is substantially perpendicular to the optical axis of the ferrule 12 . The exit surface of the diffuser plate 20 faces the kaleidoscope 30 and is substantially perpendicular to the optical axis of the ferrule 12 .

Further, the distance D between the diffuser plate 20 and the kaleidoscope 30 is equal to or less than the square root of the incident area E where the laser light diffused and transmitted through the diffuser plate 20 enters the kaleidoscope 30 . More specifically, the distance between the exit surface of the diffusion plate 20 and the opening 32 at one end of the kaleidoscope 30 is the area of the opening 32 at the one end where the laser light diffused and transmitted through the diffusion plate 20 enters the kaleidoscope 30. less than or equal to the square root. The incident area E is the opening area of the opening 32 at one end and the cross-sectional area of the transmission line 31 .

Further, the diffuser plate 20 diffuses the transmitted laser light by making the exit surface rougher than the entrance surface. The exit surface may be rougher than the entrance surface, or both the exit surface and the entrance surface may be roughened.

From the viewpoint of laser resistance, the diffusion plate 20 is preferably made of an inorganic material, particularly inorganic glass. However, this does not deny the use of translucent resin materials such as acrylic and polycarbonate. From the viewpoint of laser resistance, the diffuser plate 20 is configured to have diffusibility by subjecting the glass surface to diffusion processing. For example, by applying a surface treatment such as texturing or laser processing to form fine irregularities (texturing, microprisms, etc.) on the surface of the transparent panel, or by printing or etching a dot pattern on the surface of the transparent panel. , may be configured to have light diffusing properties. For the purpose of reducing light loss, it is preferable to apply AR coating to the entrance surface and the exit surface of the diffuser plate 20 . Note that the AR coating is preferably an inorganic film from the viewpoint of laser resistance. From the viewpoint of transmittance, a multilayer film is preferable, but an inexpensive single-layer film may be used.

The diffuser plate 20 may be a milky-white diffuser plate in which a light diffusing material (light scattering material) is dispersed inside the glass. Such a diffuser plate 20 can be produced, for example, by dispersing air bubbles inside the glass. There is a need to.

The diffusion plate 20 may be configured by forming a milky-white light diffusion film containing a light diffusion material or the like on the surface (inner surface or outer surface) of the transparent panel. There is a need to.

[Kaleidoscope 30]
The kaleidoscope 30 of the present embodiment is a light pipe made of glass, the inner surface of which is coated with a dielectric multilayer film so as to reflect the laser wavelength with high efficiency. If the cross section is square, it is manufactured by laminating four sheets of glass.

It may be a light pipe made of metal with an inner surface coated to reflect the laser wavelength with high efficiency. For example, it can be manufactured by bending. In contrast to the later-described glass rod type, the light pipe type can directly hold the side surface and is easy to handle. Also, the kaleidoscope 30 may be a large-diameter glass fiber having a polygonal core, or a capillary shape.

Alternatively, it may be a glass rod made of a translucent member such as glass. When the kaleidoscope 30 is a glass rod, the outer shape of the transmission line 31 and the kaleidoscope substantially match.

The central axis of the kaleidoscope 30 substantially coincides with the central axis O described above and substantially coincides with the optical axis of the ferrule 12 . The central axis O of the kaleidoscope 30 is a straight line perpendicular to the aperture plane of the aperture 32 at one end of the kaleidoscope 30 and passing through the center of the aperture plane.

The kaleidoscope 30 also has a transmission line 31 that transmits the laser light guided to the optical fiber 11 . The kaleidoscope 30 emits laser light that has passed through the transmission line 31 . In the kaleidoscope 30, the cross section of the transmission line 31 is polygonal when the transmission line is cut along a plane perpendicular to the direction in which the laser light is transmitted. If the transmission line 31 of the kaleidoscope 30 has a polygonal shape, the guided laser light is guided inside the kaleidoscope 30 while being repeatedly reflected, so the laser light guided inside is easily mixed. Become. Thus, the kaleidoscope 30 mixes and transmits the laser light guided through the optical fiber 11 . In other words, even if laser beams guided through one or more optical fibers 11 enter the kaleidoscope 30, the kaleidoscope 30 mixes the laser beams guided by the optical fibers 11 and outputs the mixed laser beams. emit.

Here, the polygonal cross-section of the transmission line 31 includes not only a regular polygon but also a substantially polygonal shape. In other words, some or all of the faces forming the polygon may be not only flat but also curved or wavy. The cross section of the transmission line 31 may have at least one straight side, and the remaining sides may be arcuate.

The configuration of the kaleidoscope 30 of this embodiment will be described.

The kaleidoscope 30 has a transmission line 31 surrounded by mirror surfaces and through which laser light passes. Also, the kaleidoscope 30 is formed with an opening 32 at one end and an opening 33 at the other end. The kaleidoscope 30 is fixed to the lamp 5 with a plate spring or the like.

A transmission line 31 is a space in the kaleidoscope 30 from an opening 32 at one end to an opening 33 at the other end, through which laser light passes. That is, in the transmission line 31, the laser light passes from the opening 32 at one end to the opening 33 at the other end. Also, the diameter of the transmission line 31 (the diameter of the opening 32 at one end and the diameter of the opening 33 at the other end) is smaller than the diameter of the fluorescent portion 40 and larger than the core diameter of the optical fiber 11 .

The one end opening 32 and the other end opening 33 are openings formed at one end and the other end of the kaleidoscope 30 . An opening 32 at one end serves as an incident surface on which laser light guided through the optical fiber 11 is incident. Also, the opening 33 at the other end serves as an emission surface from which the laser light guided through the optical fiber 11 is emitted.

As shown in FIG. 2, it is fixed to the lamp 5 by a plate spring or the like.

As shown in FIG. 3A, the kaleidoscope 30 is also arranged on the optical path between the optical fiber 11 and the wavelength conversion element 41 of the fluorescent section 40 . Specifically, the kaleidoscope 30 is arranged so that one end (opening 32 at one end) faces the output surface 11a of the optical fiber 11, and the other end (opening 33 at the other end) is the fluorescent portion 40. are arranged to face the

Also, the kaleidoscope 30 collectively emits laser beams transmitted through one or more optical fibers 11 . As shown in FIG. 2, the kaleidoscope 30 collectively emits the laser beams of the four laser light sources 83 transmitted by the optical fiber 11. The light may be collected into one and emitted.

Also, the kaleidoscope 30 is detachable from the lamp 5 . The kaleidoscope 30 is fixed to the lamp 5 by a fixing member such as a spring.

[Light fixture 5]
The lamp 5 is used to convert the wavelength of the laser light from the excitation light source 3 transmitted through the optical fiber 11 and emit it as illumination light. The lamp 5 is composed of, for example, a fiber coupling made of stainless steel, a lens made of glass, a holder made of aluminum, and an outer shell made of aluminum.

In this embodiment, the lamp 5 has a fluorescent portion 40 , a heat sink 151 for dissipating heat generated by the fluorescent material, an exterior portion 153 , a lens 158 and a reflecting member 157 .

<Fluorescent part 40>
The fluorescent part 40 is a wavelength converter that converts the laser light mixed in the kaleidoscope 30 into fluorescent light. The fluorescent part 40 is a flat plate. In the present embodiment, the phosphor section 40 is a structure in which a phosphor layer (wavelength conversion element 41) and the like are formed on a sapphire substrate 42, for example. The sapphire substrate 42 is fixed to the heat sink 151 while being in contact with the heat sink 151 .

The wavelength conversion element 41 wavelength-converts the laser light incident on one surface and emits it from the other surface. More specifically, the laser light transmitted through the kaleidoscope 30 is incident on one surface (on the kaleidoscope 30 side) of the wavelength conversion element 41 . In this embodiment, the intensity distribution of the light incident on one surface of the wavelength conversion element 41 is made uniform, and is substantially uniform on the laser beam irradiation surface. The laser light incident on one surface of the wavelength conversion element 41 is wavelength-converted and emitted from the other surface (reflecting member 157 side).

The wavelength conversion element 41 is formed in a plate shape, for example. The wavelength conversion element 41 contains a phosphor that emits wavelength-converted light by laser light, and the phosphor is dispersed and held in a binder that is a transparent material made of ceramic such as glass or silicone resin. The wavelength conversion element 41 is, for example, a YAG (Yttrium Aluminum Garnet)-based phosphor, a cousin-based phosphor, an escasun-based phosphor, a BAM (Ba, Mg, Al)-based phosphor, or the like. can be selected. The binder is not limited to ceramic and silicone resin, and other transparent materials such as transparent glass may be used.

In the example shown in FIGS. 2 and 3A, the wavelength conversion element 41 receives laser light emitted from the kaleidoscope 30, converts the wavelength of the incident laser light, emits the wavelength-converted wavelength-converted light, and emits white illumination. In the case of , part of the laser light is diffusely transmitted. For illumination of a specific color, a configuration in which the laser light is not diffusely transmitted may be used. More specifically, the wavelength conversion element 41 has a function of wavelength-converting part of the light incident on one surface on the kaleidoscope 30 side. In the present embodiment, the wavelength conversion element 41 receives laser light incident on one surface of the kaleidoscope 30, converts the wavelength of the incident laser light, converts the wavelength of the incident laser light, and converts the wavelength of the laser light (wavelength laser light that has passed through the wavelength conversion element 41 without being converted) is emitted from the other surface. Wavelength-converted light and laser light may be collectively referred to simply as light.

Note that the loss associated with wavelength conversion turns into heat. Since the wavelength conversion element 41 has a temperature quenching characteristic in which the wavelength conversion efficiency decreases as the temperature increases, the heat dissipation of the wavelength conversion element 41 is very important. A sapphire substrate 42 is supported by a heat sink 151 . More specifically, the sapphire substrate 42 is fixed to the other end surface of the heat sink 151 at a position that intersects the central axis of the heat sink 151 and is thermally connected to the heat sink 151 . In other words, one surface of the sapphire substrate 42 is brought into contact with the other end surface of the heat sink 151 in order to facilitate the dissipation of heat generated in the wavelength conversion element 41 through the sapphire substrate 42 . Here, as shown in FIG. 2, the central axis of the heat sink 151 is an axis that passes through the center of the lamp 5 in the longitudinal direction when the lamp 5 is elongated, for example, and coincides with the central axis O. .

Although the sapphire substrate 42 having high thermal conductivity is used as the substrate in this embodiment, the use of a transparent substrate such as glass is not excluded. Further, the sapphire substrate 42 is provided with an AR film for transmitting the laser with high efficiency toward the kaleidoscope 30 side in order to increase the efficiency of light, and the lens 158 side is provided with an AR film for transmitting the laser with high efficiency and transmitting the wavelength-converted light. is preferably formed by a first clock mirror that reflects the light.

As shown in FIG. 3A, the wavelength conversion element 41 may be, for example, a red phosphor, a green phosphor, a blue phosphor, or the like. Converted light may be emitted. In this case, these wavelength-converted lights of red light, green light, and blue light may be mixed to produce white light.

In the present embodiment, the wavelength conversion element 41 absorbs a part of the blue laser light from the excitation light source 3, for example, and converts the green to yellow wavelength-converted light and the light emitted without being absorbed by the wavelength conversion element 41. Combined with the blue laser light, a pseudo-white wavelength-converted light is emitted. When the excitation light source 3 emits blue laser light, the wavelength conversion element 41 may include multiple types of phosphors that absorb part of the blue laser light and convert the wavelength from green to yellow. good. The sapphire substrate 42 is preferably thick in order to improve thermal conductivity, but is preferably thinner than the effective diameter of the kaleidoscope in order to improve uniformity of incident laser light in the wavelength conversion element.

<Heat sink 151>
As shown in FIG. 2 , the heat sink 151 is a heat dissipation member for dissipating heat generated in the kaleidoscope 30 and the wavelength conversion element 41 . The heat sink 151 holds the fluorescent part 40 arranged at a position intersecting the central axis O. As shown in FIG.

The heat sink 151 has a plurality of fins and an insertion portion 151a.

The insertion portion 151 a holds the kaleidoscope 30 . The insertion portion 151a is a holding portion that holds the kaleidoscope 30 while the kaleidoscope 30 is inserted. Also, the insertion portion 151a fixes the kaleidoscope 30 in a predetermined posture. Further, the insertion portion 151a is formed at a position that overlaps (coincides with) the central axis O of the heat sink 151 indicated by the dashed line.

<Exterior part 153>
The exterior part 153 is connected to the heat sink 151 and arranged on the downstream side of the optical path. Specifically, the exterior part 153 is arranged downstream of the wavelength conversion element 41 in the optical path. Moreover, the exterior part 153 is a bottomless cylindrical body having an opening that opens before and after the optical path.

<Reflection member 157>
The reflecting member 157 reflects the wavelength-converted light emitted from the wavelength conversion element 41 approximately toward the lens 158 . The reflecting member 157 is a bowl-shaped member whose diameter increases from the wavelength conversion element 41 toward the lens 158 . The reflecting member 157 is fixed to the other end surface of the heat sink 151 so as to surround the wavelength conversion element 41 and face the lens 158 .

<Lens 158>
Lens 158 is, for example, a Fresnel lens. The lens 158 is fixed to the exterior part 153 so as to close the opening of the exterior part 153 . Specifically, the lens 158 is fixed to the exterior portion 153 in a posture facing the wavelength conversion element 41, and the wavelength-converted light emitted from the wavelength conversion element 41 is incident thereon. Then, the lens 158 controls the distribution of the wavelength-converted light so as to perform predetermined illumination, and emits the light.

[Experimental result]
Experimental results of the lighting device 1 according to the embodiment will be described below.

In this experiment, the wavelength of the laser light was 455 nm, and the optical fiber 11 with a core diameter of 400 μm was used. A light pipe was used as the kaleidoscope 30 . The kaleidoscope 30 has an inner diameter of 2×2 mm square of the opening 32 at one end and the opening 33 at the other end of the kaleidoscope 30, the reflectance of the inner surface of the kaleidoscope 30 is 99%, and the length is 8 mm. was used. The diffusion plate 20 used has a thickness of 0.7 mm and a square of 4×4 mm.

4A and 4B show the light color on the chromaticity coordinates (Cx, Cy) of the light emitted from the lighting device 1 according to the embodiment, and FIG. is a diagram showing the light color of .

As shown in FIG. 4, the light emitted from the illumination device 1 of the present embodiment has chromaticity coordinates in which Cx is about 0.436 and Cy is about 0.402. In FIG. 4, the chromaticity change amount of this embodiment is 0.0005. Therefore, the color of the light emitted by the illumination device 1 of the present embodiment is substantially uniform.

FIG. 5A is a diagram illustrating the luminance distribution of light emitted from the wavelength conversion element 41 of the illumination device 1 according to the embodiment. FIG. 5A illustrates the luminance distribution at point A1 on the chromaticity coordinates of FIG. FIG. 5B illustrates the luminance distribution of light emitted from the wavelength conversion element 41 of the illumination device 1 according to the embodiment, and is a diagram different from FIG. 5A. FIG. 5B illustrates the luminance distribution at point A2 on the chromaticity coordinates of FIG. The light emitted from the wavelength conversion element 41 is light containing laser light and wavelength-converted light. 5A and 5B, the horizontal axis indicates the width of light emitted from the wavelength conversion element 41, and the position of the central axis O is 0 (mm). The position 0 (mm) of the central axis O substantially coincides with the optical axis of the light emitted from the wavelength conversion element 41 . Also, the vertical axis indicates the luminance distribution.

As shown in FIGS. 5A and 5B, the luminance distribution of the light emitted from the wavelength conversion element 41 has a rectangular shape, and the peak portion is smoothed (substantially uniformed). Such laser light is a top-hat type laser light. In other words, the illumination device 1 according to the present embodiment irradiates the illumination surface, which is the object, with a high degree of uniformity. The degree of uniformity is the ratio of the minimum radiance to the maximum radiance of the light irradiated onto the irradiation surface, which is the object, and is an index indicating the variation (uniformity) of brightness.

FIG. 6 is a diagram showing the relationship between the length of the kaleidoscope 30 of the illumination device 1 according to the embodiment, that is, the length of the transmission line 31, and the amount of chromaticity change.

As shown in FIG. 6, black triangles indicate the case where the lighting device 1 uses the first diffusion plate having a small diffusion degree. Further, the black rhombus indicates the case where the illumination device 1 uses a second diffuser plate having a higher degree of diffusion than the first diffuser plate.

According to FIG. 6, in both cases of using the first diffusion plate and the second diffusion plate, the longer the kaleidoscope 30 becomes, the more the amount of chromaticity change tends to decrease. That is, the longer the kaleidoscope 30 is, the easier it is for the laser light emitted from the emission surface 11a of the optical fiber 11 to be mixed when transmitted inside the kaleidoscope 30 . Therefore, the kaleidoscope 30 can emit laser light with a reduced amount of chromaticity change, that is, laser light with high color-mixing property in which color spots of light are suppressed. Also, since the second diffusion plate has a higher degree of diffusion than the first diffusion plate, even if the length of the light pipe is short, the amount of chromaticity change is smaller than that of the first diffusion plate.

FIG. 7 is a diagram illustrating the radiance of light emitted from the kaleidoscope 30 of the illumination device 1 according to the embodiment, and a diagram illustrating the relationship between the cross-sectional shape of the kaleidoscope 30 and the uniformity of light. .

(a) of FIG. 7 illustrates the radiance distribution of laser light on the exit surface of the kaleidoscope 30 when the cross-sectional shape of the kaleidoscope 30 is changed. In FIG. 7A, when the central axis O of the kaleidoscope 30 is deviated from the optical axis of the ferrule 12, the laser beam emitted from the kaleidoscope 30 is applied to the irradiated surface. 3 illustrates a radiance distribution; Further, in FIG. 7A, when the central axis O of the kaleidoscope 30 and the optical axis of the ferrule 12 are substantially aligned, the laser beam emitted from the kaleidoscope 30 is applied to the irradiated surface. radiance distribution.

FIG. 7B is a diagram illustrating the relationship between the cross-sectional shape of the kaleidoscope 30 and the uniformity of the illumination device 1 on the output surface of the kaleidoscope 30 . FIG. 7B illustrates a case where the central axis O of the kaleidoscope 30 is deviated from the optical axis of the ferrule 12 and a case where the central axis O of the kaleidoscope 30 and the optical axis of the ferrule 12 substantially match. are doing.

As shown in FIG. 7A, when the central axis O of the kaleidoscope 30 is deviated from the optical axis of the ferrule 12, the radiation becomes It can be seen that there are spots in the luminance. Even when the central axis O of the kaleidoscope 30 substantially coincides with the optical axis of the ferrule 12, the radiance becomes uneven as the number of corners of the polygon that is the cross-sectional shape of the kaleidoscope 30 increases. I understand.

7B, when the central axis O of the kaleidoscope 30 is deviated from the optical axis of the ferrule 12, as the number of corners of the polygon that is the cross-sectional shape of the kaleidoscope 30 increases, , the uniformity of the light is degraded. Further, even when the central axis O of the kaleidoscope 30 substantially coincides with the optical axis of the ferrule 12, the degree of light uniformity decreases as the number of polygonal corners of the cross-sectional shape of the kaleidoscope 30 increases.

In other words, it was found that as the cross-sectional shape of the kaleidoscope 30 approaches a circular shape, spots occur in the radiance distribution of light and the degree of uniformity decreases, that is, the mixing ability of the kaleidoscope 30 decreases. For this reason, it is preferable that the cross-sectional shape of the kaleidoscope 30 has a small number of corners, and in particular, triangles, quadrilaterals, pentagons, and the like are preferable.

This is because as the number of corners of the transmission line 31 increases, the length of each side of the polygon becomes shorter, so that the laser light tends to converge on the central axis O of the transmission line 31 . On the other hand, since the length of one side of a polygon such as a triangle or a square is long, it is difficult for the laser light to converge on the central axis O of the transmission line 31 .

[Comparative example]
FIG. 8A is a diagram illustrating a luminance distribution of light emitted from a wavelength conversion element of an illumination device according to a comparative example; Also, FIG. 8A illustrates the luminance distribution at point B1 on the chromaticity coordinates of FIG. FIG. 8B is a diagram different from FIG. 8A exemplifying the luminance distribution of light emitted from the wavelength conversion element of the lighting device according to the comparative example. FIG. 9A is a schematic diagram illustrating a laser light source according to a comparative example used to illustrate the luminance distribution of FIG. 8A. FIG. 9B is a schematic diagram illustrating a laser light source according to a comparative example used to illustrate the luminance distribution of FIG. 8B.

FIG. 8B differs from FIG. 8A in the setup of the injection into the optical fiber 11 . The relative positions of the laser 83, the prism 85, the lens 87, and the ferrule 88 (fiber incident end face) are shown by solid lines in FIG. deviated from The relative positions of the laser 83, prism 85, lens 87, and ferrule 88 (fiber incident end face) in the laser light source of FIG. 9A are the same as those of FIG.

The problem is that the luminance distribution on the fiber output side changes depending on the alignment on the fiber input side. The chromaticity will change depending on the assembly accuracy on the incident side and the like. In the present invention, by using a circular core fiber and a kaleidoscope, it is possible to stabilize chromaticity between instruments at low cost.

Also, FIG. 8B illustrates the luminance distribution at point B2 on the chromaticity coordinates of FIG.

The illumination device according to the comparative example does not have the kaleidoscope 30 in which the transmission line 31 has a polygonal cross section as shown in FIG. It is a lighting device that is The light emitted from the wavelength conversion element of this illumination device is light containing laser light and wavelength-converted light. 8A and 8B, the horizontal axis indicates the width of light emitted from the wavelength conversion element, and the position of the central axis O is 0 (mm). A position 0 (mm) of the central axis O substantially coincides with the optical axis. Also, the vertical axis indicates the luminance distribution.

As shown in FIGS. 8A and 8B, the luminance distribution of the light emitted from the wavelength conversion element has a parabolic shape, the emitted light has spots, and the luminance distribution of the emitted light is uniform. not In other words, the illumination device of the comparative example irradiates the illumination surface, which is the object, with a low degree of uniformity.

In addition, as shown in FIG. 4, the light emitted from the lighting device of the comparative example has a chromaticity coordinate Cx of about 0.425 to about 0.428 and Cy of about 0.398 to about 0.399. degree. In FIG. 4, the chromaticity variation is 0.0045. Therefore, the color of the light emitted by the lighting device of the comparative example is not uniform. That is, the light emitted from the lighting device of the comparative example has a higher chromaticity change amount and a lower degree of uniformity than the light emitted from the lighting device 1 of the present embodiment. In addition, the luminance distribution of light has spots. For this reason, the illumination device of the comparative example cannot emit uniform light.

[Effect]
Next, the effects of the illumination device 1 according to this embodiment will be described.

As described above, the illumination device 1 of the present embodiment includes the laser light source 83 that emits laser light, the optical fiber 11 that guides the laser light, and the transmission device that transmits the laser light guided by the optical fiber 11 . A kaleidoscope 30 having a transmission line 31 and including the transmission line 31 , and a wavelength conversion element 41 for emitting wavelength-converted light by laser light emitted from the transmission line 31 . Also, the kaleidoscope 30 is arranged between the optical fiber 11 and the wavelength conversion element 41 . When the transmission line 31 is cut along a plane perpendicular to the direction in which the laser light is transmitted, the cross section of the transmission line 31 has a polygonal shape.

According to this, the kaleidoscope 30 mixes the laser light guided through the optical fiber 11 , so that the mixed laser light can be made incident on the wavelength conversion element 41 . In addition, since the kaleidoscope 30 has a polygonal cross section, the light transmitted through the kaleidoscope 30 can be mixed.

Moreover, since there is no need to process the optical fiber 11 having a circular cross-sectional shape to have a polygonal cross-sectional shape, the manufacturing cost of the illumination device 1 is unlikely to increase.

Therefore, in the illumination device 1 in which the laser light source 83 using the optical fiber 11 and the wavelength-converted light by the wavelength conversion element 41 are separated, it is possible to suppress an increase in manufacturing cost and stabilize chromaticity. In other words, the illumination device 1 can improve the uniformity of the emitted light.

The lighting device 1 of the present embodiment further includes a diffusion plate 20 arranged between the optical fiber 11 and the kaleidoscope 30 for diffusing and transmitting the laser light guided by the optical fiber 11 . Then, the laser light diffused and transmitted through the diffusion plate 20 is incident on the kaleidoscope 30 .

According to this, the diffusion plate 20 can diffuse and transmit the laser light guided to the optical fiber 11 . Therefore, the diffuser plate 20 can make the diffused and transmitted laser light incident on the kaleidoscope 30 . That is, the kaleidoscope 30 can emit more mixed light. As a result, the illumination device 1 can emit more uniform light.

Further, in the illumination device 1 of the present embodiment, the distance between the diffusion plate 20 and the kaleidoscope 30 is equal to or less than the square root of the incident area of the laser light diffused and transmitted through the diffusion plate 20 and incident on the kaleidoscope 30. .

According to this, the diffusion plate 20 diffuses and transmits the laser light, so that the wavelength conversion element 41 can emit more uniform light.

Moreover, in the illumination device 1 of the present embodiment, the kaleidoscope 30 is a light pipe.

For example, if a columnar transparent member (for example, a transparent rod) is used as the kaleidoscope 30, it is necessary to support the transparent member with respect to the optical fiber 11 by some means such as a support member. If the light-transmitting member is supported by the supporting member, the contact surface between the supporting member and the light-transmitting member will have different refractive indices, which may cause a difference in the intended mixing ability of the light-transmitting member. Therefore, it becomes difficult to design the translucent member and the support member for supporting the translucent member in order to obtain the desired mixing ability.

In addition, in the illumination device 1 of the present embodiment, the cross section of the transmission line 31 is polygonal with fewer angles than the decagon.

According to this, the illumination device 1 can make the emitted light more uniform.

(Other modifications, etc.)
As described above, the present disclosure has been described based on the embodiments, but the present disclosure is not limited to the above embodiments.

For example, the illumination device 1 according to the above embodiment uses the diffuser plate 20, but the diffuser plate 20 may not be provided as shown in FIG. 3B. FIG. 3B is a partially enlarged cross-sectional view illustrating the optical fiber 11, the ferrule 12, the kaleidoscope 30, the wavelength conversion element 41, etc. of the illumination device 1 according to another modification. As shown in FIG. 3B, the illumination device 1 can make the luminance distribution of emitted light uniform without using the diffuser plate 20 . For this reason, the diffusion plate 20 is not an essential component when the illumination device 1 does not need to be downsized. Further, as shown in FIG. 6, black circles indicate the case where the diffuser plate 20 is not used in the illumination device 1 (that is, the case where the diffuser plate 20 is not arranged between the optical fiber 11 and the kaleidoscope 30). According to FIG. 6, the longer the kaleidoscope 30, the more the chromaticity variation tends to decrease. In other words, as the length of the kaleidoscope 30 increases, the illumination device 1 becomes larger, but the laser light emitted from the emission surface 11a of the optical fiber 11 is more likely to be mixed when guided inside the kaleidoscope 30. Become. Therefore, the kaleidoscope 30 can emit laser light with a reduced amount of chromaticity change, that is, laser light with high color-mixing property in which color spots of light are suppressed.

Further, in the illumination device 1 according to the above-described embodiment, as shown in FIG. 3C, the end of the optical fiber 11 allows the laser beam to enter the kaleidoscope 30 without providing the ferrule 12 at the end of the optical fiber 11. It may be held by the holding member 99 as follows. FIG. 3C is a partially enlarged cross-sectional view illustrating the optical fiber 11, the kaleidoscope 30, the wavelength conversion element 41, and the like of the illumination device 1 according to another modification. As shown in FIG. 3C, the coating at the end of optical fiber 11 is removed to expose the cladding of optical fiber 11 and the exposed cladding is inserted into opening 32 at one end of kaleidoscope 30 . When the kaleidoscope 30 is a light pipe, the kaleidoscope 30 has a bottomless cylindrical shape. As described above, in the illumination device 1 of the present embodiment, the optical fiber 11 has the emission surface 11a from which the guided laser beam is emitted. The end on the output surface 11 a side is held so as to be positioned within the transmission line 31 of the kaleidoscope 30 . As shown in FIG. 7, in this embodiment using the kaleidoscope 30, the degree of uniformity at the aperture surface 33 of the kaleidoscope 30 can be increased regardless of the incident position of the laser light. The positional relationship between the surface 11a and the kaleidoscope 30 can be loose, and the cost can be reduced. According to this, the optical fiber 11 can be held in the kaleidoscope 30 without providing the ferrule 12 at the end of the optical fiber 11 . Therefore, it is possible to reduce the number of parts of the illumination device 1, and it is possible to adapt the end face to a rough state in the polishing process and the cleave for making the end face a mirror surface, and it is possible to reduce the cost. becomes. In addition, in the illumination device 1 according to the above-described embodiment, the end of the optical fiber 11 may be held by the holding member 99 by providing the ferrule 12 at the end of the optical fiber 11 as shown in FIG. 3D. The ferrule 12 does not have to be placed inside the transmission line 31 of the kaleidoscope 30 . FIG. 3D is a partially enlarged cross-sectional view illustrating the optical fiber 11, the kaleidoscope 30, the wavelength conversion element 41, and the like of the illumination device 1 according to another modification. The optical fibers 11 used in FIGS. 3C and 3D may be bundle fibers. In addition, when a plurality of optical fibers 11 such as bundle fibers are used, the luminance distribution as it is is emitted from the plurality of optical fibers 11 . By using a kaleidoscope 30, the laser light emitted from the emission surfaces 11a of the plurality of optical fibers 11a as shown in FIG. Chromaticity change can be improved. In addition, the same problem occurs in a configuration in which multiple optical fibers are present on the incident side instead of a bundle fiber, and a single fiber is used on the output side via a fiber combiner. , a configuration in which the kaleidoscope 30 is installed is also effective.

Moreover, in the illumination device 1 of the present embodiment, the optical fiber 11 has an emission surface 11a for emitting guided laser light. A rough surface for diffusing and transmitting the laser light is formed on the emission surface 11a.

According to this, the emission surface 11 a can diffuse and transmit the laser light guided to the optical fiber 11 . Therefore, the emission surface 11 a can allow the diffused and transmitted laser light to enter the kaleidoscope 30 . That is, the kaleidoscope 30 can emit more mixed light. As a result, the illumination device 1 can make the emitted light more uniform. By roughening the end face, it is possible to obtain the same effect as installing a diffusion plate, and it is possible to reduce the size of the device.

In addition, in the illumination device 1 according to the above-described embodiment, the end on the side of the exit surface 11a is arranged inside the transmission path 32 (inside the kaleidoscope 30). Therefore, positioning of the kaleidoscope 30 with respect to the optical fiber 11 can be facilitated. Thereby, the reproducibility of the near-field pattern (NFP) on the wavelength conversion element 41 can be improved.

Further, in the illumination device 1 according to the above-described embodiment, in order to increase the uniformity (improve the uniformity) of the laser light emitted from the kaleidoscope 30, the number of angles of the cross section of the transmission line 31 in the kaleidoscope 30 is set to A kaleidoscope 30 designed by a design method that designs for reduction may be used. In addition, if the optical fiber 11 adds a component that closes the opening 32 at one end of the kaleidoscope 30, it is possible to prevent dust from entering.

In addition, in the lighting device according to the above embodiment, the optical connector is detachable from the lamp, but the means of attachment and detachment is not limited to the above, and known means may be used.

In addition, a form obtained by applying various modifications that a person skilled in the art can think of to the embodiment, and a form realized by arbitrarily combining the constituent elements and functions in the embodiment within the scope of the present disclosure. Included in disclosure.

1 lighting device 11 optical fiber 11a emission surface 20 diffusion plate 30 kaleidoscope 31 transmission line 41 wavelength conversion element 83 laser light source

Claims (7)

a laser light source that emits laser light;
an optical fiber that guides the laser light;
a kaleidoscope having a transmission line for transmitting the laser light guided to the optical fiber and including the transmission line;
a wavelength conversion element that emits wavelength-converted light by the laser light emitted from the transmission line,
The kaleidoscope is arranged between the optical fiber and the wavelength conversion element,
a cross section of the transmission line when the transmission line is cut along a plane perpendicular to the direction in which the laser light is transmitted, and is polygonal;
The kaleidoscope has an opening at one end of the kaleidoscope into which the laser light guided by the optical fiber is incident, and an opening at the other end of the kaleidoscope from which the laser light guided by the optical fiber is emitted. and
The wavelength conversion element is arranged to cover the opening at the other end of the kaleidoscope.
lighting device. further comprising a diffusion plate disposed between the optical fiber and the kaleidoscope for diffusing and transmitting the laser light guided by the optical fiber;
The illumination device according to claim 1, wherein the laser beam diffused and transmitted through the diffuser plate is incident on the kaleidoscope. The lighting device according to claim 2, wherein the distance between the diffuser plate and the kaleidoscope is equal to or less than the square root of the incident area of the laser beam diffused and transmitted through the diffuser plate and incident on the kaleidoscope. The illumination device according to any one of claims 1 to 3, wherein the kaleidoscope is a light pipe. The optical fiber has an emission surface for emitting the guided laser light,
The illumination device according to any one of claims 1 to 4, wherein a rough surface that diffuses and transmits the laser light is formed on the emission surface. The lighting device according to claim 5, wherein the end on the exit surface side is arranged in the transmission line. The lighting device according to any one of claims 1 to 6, wherein the cross section of the transmission line is a polygonal shape with fewer angles than a decagonal shape.

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