Lighting device

Abstract

To provide a lighting device which enables reduction of unevenness of illumination light.SOLUTION: A lighting device 1 emits illumination light L1 to a lighting space S1 at the outside. The lighting device 1 includes a housing 4, a light source 2, and an optical system 3. The housing 4 has an opening 4a which is open in the lighting space S1, and a lens is not located in the opening 4a. The light source 2 emits the illumination light L1. The optical system 3 is located within the housing 4 and emits the illumination light L1 from the light source 2 at a predetermined light distribution angle θ1 from the opening 4a while forming an image. An inner peripheral surface 43c of the opening 4a has a first portion and a second portion. The first portion has a portion having the smallest opening area. The second portion is located at the lighting space S1 side relative to the first portion and has an opening area larger than the opening area in the first portion. The illumination light L1 forms an image in the first portion. The inner peripheral surface 43c is located outside the light distribution area of the illumination light L1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a lighting device. [Background technology]

[0002] Lighting devices that irradiate a space with illumination light are known (for example, Patent Documents 1 to 3). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-147025 [Patent Document 2] Japanese Patent Application Publication No. 3-43903 [Patent Document 3] Japanese Patent Publication No. 2019-67605 [Overview of the project] [Problems that the invention aims to solve]

[0004] Regarding the lighting equipment, there is room for improvement in terms of the unevenness of the light emitted into the illuminated space. [Means for solving the problem]

[0005] The lighting device is disclosed.

[0006] In one embodiment, the lighting device emits illumination light into the external lighting space. The lighting device comprises a housing, a light source, and an optical system. The housing has an opening that opens into the lighting space, and no lens is located in the opening. The light source emits illumination light. The optical system is located inside the housing and emits the illumination light from the light source out of the opening at a predetermined beam angle while forming an image of it. The inner surface of the opening has a first part and a second part. The first part is the part with the smallest opening area. The second part is located closer to the lighting space than the first part, and its opening area is larger than the opening area of ​​the first part. The illumination light is imaged in the first part. The inner surface is located outside the beam of the illumination light. [Effects of the Invention]

[0007] According to the lighting device, it is possible to reduce unevenness in the illumination light illuminating the illuminated space. [Brief explanation of the drawing]

[0008] [Figure 1] This figure schematically shows an example of the configuration of a lighting device according to the first embodiment. [Figure 2] This figure shows an enlarged view of an example of the configuration of the injection opening according to the first embodiment. [Figure 3] This diagram schematically shows an example of the shape of the injection port. [Figure 4] This figure schematically shows an example of the configuration of a lighting device according to the second embodiment. [Figure 5] This figure shows an enlarged view of an example of the configuration of the injection opening according to the second embodiment. [Figure 6] This diagram schematically shows an example of a configuration obtained by omitting the plate-shaped part from the lighting device. [Figure 7] This diagram schematically shows an example of a configuration obtained by omitting the tip section from a lighting device. [Figure 8] This figure schematically shows another example of the configuration of a lighting device according to the second embodiment. [Figure 9] This figure schematically shows a first example of the configuration of a lighting device according to the third embodiment. [Figure 10] It is a figure which expands and shows an example of the inner peripheral surface of an exit opening part. [Figure 11] It is a figure which shows roughly the second example of the structure of the lighting device concerning a 3rd embodiment. [Figure 12] It is a figure which expands and shows an example of the 1st surface of an exit opening part. [Figure 13] It is a figure which shows roughly the third example of the structure of the lighting device concerning a 3rd embodiment. [Figure 14] It is a figure which shows roughly the fourth example of the structure of the lighting device concerning a 3rd embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0009] The inventor has created a technique for reducing unevenness of illumination light in a lighting device. About this, the 1st embodiment to the 3rd embodiment will be described below based on drawings.

[0010] <First Embodiment>[ Fig. 1 is a figure which shows roughly an example of the structure of a lighting device 1 concerning a 1st embodiment. As shown in Fig. 1, the lighting device 1 is a device which emits illumination light L1 to an external lighting space S1. The lighting space S1 is a space where a person can stay or pass, for example, and as a more specific example, it may be the inside of a predetermined building or a passage space connecting each room. The lighting device 1 is arranged, for example, on the ceiling part of the lighting space S1. The illumination light L1 emitted from the lighting device 1 can directly illuminate an object in the lighting space S1. The "directly" here means that the illumination light L1 emitted from the lighting device 1 is irradiated to an object without passing through optical components such as a lens and a spatial light modulation part. A person in the lighting space S1 can visually recognize the shape and color of an object illuminated by the illumination light L1. When a more uniform illumination light L1 with less unevenness is irradiated to an object, a person can visually recognize the shape and color of the object more appropriately.

[0011] As shown in Fig. 1, the lighting device 1 includes a light source 2, an optical system (hereinafter referred to as a lens optical system) 3, and a housing 4.

[0012] The housing 4 houses the light source 2 and the lens optical system 3. The housing 4 has an exit aperture (corresponding to an aperture) 4a. In the example in Figure 1, the exit aperture 4a is formed at the end of the housing 4. The light source 2 emits illumination light L1. The illumination light L1 passes through the lens optical system 3 and travels toward the exit aperture 4a, and is emitted into the illumination space S1 through the exit aperture 4a. The exit aperture 4a is a space that connects the internal space of the housing 4 and the illumination space S1. This exit aperture 4a functions as an exit for the illumination light L1 from the internal space of the housing 4 to the illumination space S1. As shown in Figure 1, a lens does not necessarily have to be located inside the exit aperture 4a. Also, optical components such as lenses and spatial light modulation units do not necessarily have to be located forward of the exit aperture 4a in the direction of emission.

[0013] If, for example, an aluminum alloy is used as the material for the housing 4, the lighting device 1 can be made lighter and its rigidity improved. The material for the housing 4 is not limited to an aluminum alloy; for example, it may be other materials such as synthetic resin. The housing 4 may be composed of a single component, or it may have a structure in which multiple components are connected, bonded, or joined together to form a single unit.

[0014] The light source 2 has an emission section (e.g., emission surface) 21 that emits illumination light L1 into the internal space of the housing 4. The illumination light L1 is, for example, visible light. 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 VCSEL (Vertical Cavity Surface Emitting Laser) or SLD (superluminescent diode). The emission section 21 of the light source 2 may be the emission end of a light-emitting element.

[0015] Alternatively, in addition to the light-emitting element, the light source 2 may further include a light guide member such as a fiber and a rod lens. The fiber includes a linear core and a cladding. The cladding has a lower refractive index than the core and covers the core. The illumination light L1 can pass through the core while undergoing total internal reflection at the interface between the core and the cladding. The rod lens has, for example, a columnar shape. The illumination light L1 can pass through the inside of the rod lens while undergoing total internal reflection at the side surface of the rod lens. Thus, the illumination light L1 from the light-emitting element can enter the incident end of a light guide member such as a fiber and a rod lens, travel through the light guide member, and exit from the exit end of the light guide member into the internal space of the housing 4. In this case, the emission part 21 of the light source 2 corresponds to the exit end of the light guide member.

[0016] The emission part 21 may include a wavelength conversion member 23, and the illumination light L1 may be fluorescence emitted from the wavelength conversion member 23. The wavelength conversion member 23 may include, for example, BaMgAl 10 O 17 :Eu, or (Sr,Ca,Ba) 10 (PO4)6Cl2:Eu,(Sr,Ba) 10 (PO4)6Cl2:Eu, etc. as a wavelength conversion material that converts excitation light into blue light. The wavelength conversion member 23 may include, for example, (Sr,Ba,Ca)5(PO4)3Cl:Eu,Sr4Al 14 O 25 :Eu, etc. as a wavelength conversion material that converts excitation light into blue-green light. The wavelength conversion member may include, for example, SrSi2(O,Cl)2N2:Eu, (Sr,Ba,Mg)2SiO4:Eu 2+ , or ZnS:Cu,Al, Zn2SiO4:Mn, etc. as a wavelength conversion material that converts excitation light into green light. The wavelength conversion member may include, for example, Y2O2S:Eu, Y2O3:Eu, SrCaClAlSiN3:Eu 2+ , CaAlSiN3:Eu, or CaAlSi(ON)3:Eu, etc. as a wavelength conversion material that converts excitation light into red light. The wavelength conversion member may include, for example, 3Ga5O 12 :Cr, etc. as a wavelength conversion material that converts excitation light into light having a wavelength in the near-infrared region.

[0017] In this case, the light source 2 also includes a light-emitting element that emits excitation light to the wavelength conversion member 23. The excitation light may be, for example, violet light with a peak near 405 nm or blue light with a peak near 450 nm. If the excitation light is light with a peak between 380 nm and 415 nm, and the wavelength conversion member 23 has red, blue, and green phosphors, the color rendering of the illumination device 1 can be improved. For example, a gallium nitride (GaN) semiconductor laser that emits violet laser light at 405 nm as excitation light may be applied to the light-emitting element.

[0018] As shown in Figure 1, the illumination light L1 from the emitter 21 of the light source 2 spreads as it travels. In other words, the size of the illumination light L1 in a cross section perpendicular to the optical axis of the light source 2 increases as you move away from the light source 2. The size of the cross section of the illumination light L1 is equal to the e of the peak value in the light intensity distribution of the illumination light L1 in a cross section perpendicular to the optical axis. 2 It may also be defined by contour lines having a light intensity of 1 / 1. Here, "e" is called Napier's number. In other words, the outer rays of the illumination light L1 in Figure 1 are defined by the e of the peak value of the light intensity distribution in a cross section perpendicular to axis AX1. 2 This is a ray with 1 / 1 the amount of light. Light outside the region enclosed by the above contour lines (i.e., the outermost rays) may be considered noise light.

[0019] The lens optical system 3 is located within the internal space of the housing 4, on the path of illumination light L1 from the light source 2 to the exit aperture 4a. The lens optical system 3 includes one or more lenses 31, and focuses the illumination light L1 from the light source 2 onto a virtual image plane IS1 on the opposite side of the exit section 21, i.e., on the side of the exit aperture 4a. In other words, the lens optical system 3 is an imaging optical system that forms a real image of the light source 2 on the image plane IS1. To put it another way, the exit section 21 of the lens optical system 3 has a conjugate relationship with respect to the image plane IS1. Note that the conjugate relationship here is not in a strict sense, but rather the part on the side of the exit aperture 4a from the exit section 21 where the illumination light L1 is most focused (the part where the size of the illumination light L1 in a cross section perpendicular to the axis AX1 of the light source 2 is smallest) can be considered as the image plane IS1.

[0020] The illumination light L1 spreads out as it travels forward of the point of most concentration. Therefore, the illumination light L1 spreads out as it travels in the illumination space S1. In other words, the lens optical system 3 concentrates the illumination light L1 on the side of the exit aperture 4a and emits it from the exit aperture 4a at a predetermined beam angle θ1. The beam angle θ1 here is, for example, the beam angle of the portion of the illumination light L1 that has half the peak intensity. The beam angle θ1 can also be called the half-power angle. The beam angle θ1 may be, for example, less than 60 degrees, less than 45 degrees, less than 30 degrees, or less than 15 degrees.

[0021] As shown in Figure 1, the lens optical system 3 may consist of a single lens 31. The lens 31 may be a spherical biconvex lens. The lens 31 is formed from a material that includes at least one of glass, such as optical glass, and resin, such as acrylic resin. Alternatively, the lens optical system 3 may include a plurality of lenses 31. The plurality of lenses 31 may be arranged at intervals along the path of illumination light L1 from the light source 2 to the exit aperture 4a. The lenses 31 may be mounted on the housing 4 via a lens holder (not shown).

[0022] The virtual image plane IS1 may be a flat surface or a curved surface. If the image plane IS1 is a curved surface, an inexpensive lens can be used as the lens 31 of the lens optical system 3. Furthermore, the lens 31 may be a spherical lens, an aspherical lens, or a free-form surface lens. Also, the lens 31 may have a continuous curved surface. For example, the main surface of the lens 31 through which the illumination light L1 passes may be composed only of a curved surface without any steps. In other words, the lens 31 does not have to be a Fresnel lens. This reduces scattering or reflection in the lens 31. As a result, a comfortable illumination space with less glare can be realized.

[0023] As shown in Figure 1, the light source 2, the lens optical system 3, and the exit aperture 4a may be aligned in a straight line. For example, the light source 2, the lens optical system 3, and the exit aperture 4a may be aligned along the vertical direction. In the example in Figure 1, the optical axis of the light source 2, the optical axis of the lens optical system 3, and the central axis of the exit aperture 4a are approximately coincident. Hereafter, these axes will be referred to as axis AX1. If the lens optical system 3 includes multiple lenses 31, the multiple lenses 31 are aligned along axis AX1.

[0024] In the example shown in Figure 1, the housing 4 includes a cylindrical portion 41, a base portion 42, and an exit opening 43. The cylindrical portion 41 has a cylindrical shape, and in a more specific example, it has a cylindrical shape. The lens optical system 3 is located inside the cylindrical portion 41. In the example shown in Figure 1, the central axis of the cylindrical portion 41 is aligned with the optical axis direction of the lens optical system 3.

[0025] In the example shown in Figure 1, a shielding portion 44 is located at the first peripheral edge of the cylindrical portion 41. The shielding portion 44 has, for example, a plate-like shape and is positioned such that its thickness direction is aligned with the axis AX1. The shielding portion 44 has, for example, a disc-like shape and its peripheral edge is connected to the first peripheral edge of the cylindrical portion 41. The shielding portion 44 has an opening 4b, which penetrates the shielding portion 44 in its thickness direction. The shape of the opening 4b in plan view may be circular. In the example shown in Figure 1, the diameter of the opening 4b is smaller than the inner diameter of the cylindrical portion 41.

[0026] The base portion 42 has, for example, a plate-like shape and is positioned such that its thickness direction is aligned with the axis AX1. The emission portion 21 of the light source 2 is fixed to the base portion 42. In the example of Figure 1, an opening is formed in the center of the base portion 42, and the light source 2 is positioned within this opening. The base portion 42 is connected to the shielding portion 44 such that the light source 2 faces the opening 4b in the direction aligned with the axis AX1. The base portion 42 has, for example, a disc-like shape with an outer diameter larger than the opening 4b, and its peripheral edge is connected to the shielding portion 44.

[0027] The central portion of the illumination light L1 emitted from the light source 2 passes through the aperture 4b without hitting the shielding portion 44 and enters the lens optical system 3. In the example in Figure 1, the outer edge of the illumination light L1 that passes through the aperture 4b without hitting the shielding portion 44 is schematically shown by a dashed line. Conversely, the outer portion of the illumination light L1 enters the shielding portion 44. In the example in Figure 1, the outer portion of the illumination light L1 enters the inner surface 44c that forms the aperture 4b of the shielding portion 44. The inner surface 44c of the shielding portion 44 may, for example, absorb the illumination light L1. The reflectance of the inner surface 44c of the shielding portion 44 with respect to the illumination light L1 may be, for example, 50% or less, 40% or less, 20% or less, or 10% or less.

[0028] The inner surface 44c of the shielding portion 44 may be inclined so as it approaches the axis AX1 as it approaches the lens optical system 3. In the example in Figure 1, this inner surface 44c is shown by a dashed line. According to this, the outer portion of the illumination light L1 emitted from the light source 2 is reflected by the inner surface 44c to the side opposite to the lens optical system 3.

[0029] An injection opening 43 is located at the second peripheral edge of the cylindrical portion 41, opposite to the first peripheral edge. The injection opening 43 has, for example, a plate-like shape, and is positioned so that its thickness direction is aligned with the axis AX1. The injection opening 43 has, for example, a disc-like shape, and its peripheral edge is connected to the second peripheral edge of the cylindrical portion 41. The injection opening 43 has an injection opening 4a. The injection opening 4a penetrates the injection opening 43 in its thickness direction.

[0030] The thickness of the ejection opening 43 (in other words, the thickness h2 of the ejection opening 4a) may be greater than the thickness of the base portion 42 or the thickness of the shielding portion 44 (in other words, the thickness of the opening 4b). The thickness h2 of the ejection opening 4a may be, for example, 5 mm or more, or 10 mm or more. As a specific example, the thickness h2 is about 10 mm. The thickness of the opening may also be called the depth or height of the opening.

[0031] Figure 2 is an enlarged view showing an example of the configuration of the exit aperture 43 according to the first embodiment. In the example of Figures 1 and 2, the exit aperture 43 has a first surface 43a on the lens optical system 3 side, a second surface 43b on the illumination space S1 side, and an inner circumferential surface 43c. The first surface 43a faces the internal space of the housing 4 and faces the lens optical system 3 in the direction along the axis AX1 (see Figure 1). The second surface 43b is the surface of the exit aperture 43 opposite to the first surface 43a. The second surface 43b may also face the illumination space S1. The inner circumferential surface 43c connects the first surface 43a and the second surface 43b, forming the exit aperture 4a. As shown in Figure 2, the first end 4aa on the lens optical system 3 side of the exit aperture 4a is located on the first surface 43a, and the second end 4ab on the illumination space S1 side of the exit aperture 4a is located on the second surface 43b.

[0032] In the example in Figure 2, the opening area of ​​the ejection opening 4a is minimized at the first end opening 4aa. That is, the inner circumferential surface 43c has a first portion where the opening area is minimized. In the example in Figure 2, the first portion is the part of the inner circumferential surface 43c that forms the first end opening 4aa. The size of the first end opening 4aa where the opening area is minimized may be, for example, 5 mm or more and 50 mm or less. The size of the first end opening 4aa may be the diameter of the first end opening 4aa if the first end opening 4aa is circular, or the length of the diagonal of the first end opening 4aa if the first end opening 4aa is rectangular.

[0033] As shown in Figure 1, the illumination light L1 transmitted through the lens optical system 3 is imaged at the image plane IS1 at the first aperture 4aa (i.e., the first portion) of the inner surface 43c. In other words, the position of the image plane IS1 in the direction of propagation of the illumination light L1 is near the first portion. The direction of propagation of the illumination light L1 is, for example, along the axis AX1.

[0034] Here, "the illumination light L1 forms an image in the first part" means that the image plane IS1 is located within the focusing range described below. That is, the focusing range has a width h1 in the direction of propagation of the illumination light L1, and the center of the focusing range is equal to the position of the first part in the direction of propagation of the illumination light L1. The width h1 may be equal to the thickness h2 of the exit aperture 4a in the direction of propagation of the illumination light L1. Alternatively, the width h1 may be 80%, 60%, 40%, or 20% of the thickness h2.

[0035] The aperture area of ​​the exit aperture 4a in the first part can be set to be larger than the cross-sectional area of ​​the illumination light L1 at the same position as the first part. For example, the inner diameter of the inner circumferential surface 43c in the first part can be set to be larger than the optical diameter of the illumination light L1 at the same position as the first part. This reduces the possibility that the illumination light L1 that forms an image on the image plane IS1 will be incident on the first surface 43a of the exit aperture 43. In other words, the illumination light L1 is less likely to be blocked by the exit aperture 43, and the illumination device 1 can emit the illumination light L1 from the exit aperture 4a with a greater amount of light.

[0036] If the image plane IS1 of the illumination light L1 is located near the first part, the aperture area of ​​the first part can be set smaller while suppressing the incidence of the illumination light L1 onto the first surface 43a. In other words, the minimum aperture area of ​​the exit aperture 4a can be made smaller. As a result, it is difficult for people in the illuminated space S1 to see inside the housing 4 through the exit aperture 4a. Therefore, the presence of the illumination device 1 can be further reduced. When the presence of the illumination device 1 is reduced, people in the illuminated space S1 can more easily focus on the surrounding environment within the illuminated space S1 and more easily pay attention to the design within the illuminated space S1.

[0037] Incidentally, the illumination light L1 emitted from the light source 2 can be reflected and scattered inside the housing 4. For example, the illumination light L1 can be reflected and scattered on the inner surface 44c of the aperture 4b. Also, the illumination light L1 can be slightly reflected and scattered on the surface of the lens 31. Furthermore, when this reflected and scattered light is incident on the inner wall of the housing 4, it is reflected and scattered even more. When this reflected and scattered light (hereinafter also called unwanted light) generated by the reflection and scattering of illumination light L1 is emitted into the illumination space S1 through the exit aperture 4a, it causes unevenness in the illumination light L1.

[0038] If the minimum aperture area of ​​the emission aperture 4a can be reduced, it is possible to suppress the emission of such unwanted light through the emission aperture 4a into the illumination space S1. As a result, the illumination device 1 can emit more uniform illumination light L1 into the illumination space S1.

[0039] Figure 3 is a schematic diagram showing an example of the shape of the exit aperture 4a. Figures 3(a) to 3(c) show the shape of the exit aperture 4a as viewed along axis AX1. The shape of the exit aperture 4a may be circular as shown in Figure 3(a), elliptical as shown in Figure 3(b), or rectangular as shown in Figure 3(c). The shape of the exit aperture 4a in plan view may be the same as, or more specifically similar to, the shape of the illumination light L1 on the image plane IS1. For example, if the shape of the illumination light L1 on the image plane IS1 is circular, a circular shape as shown in Figure 3(a) may be applied as the shape of the exit aperture 4a in plan view. This allows the illumination light L1 that forms an image on the image plane IS1 to pass through the exit aperture 4a appropriately, while further reducing the aperture area of ​​the exit aperture 4a. This further reduces unwanted light emitted into the illumination space S1 through the exit aperture 4a, while further reducing the presence of the illumination device 1. Furthermore, the shape of the first portion (in this case, the first end opening 4aa) of the exit aperture 4a, which has the smallest aperture area, only needs to be the same as the shape of the illumination light L1, and a different shape from the shape of the illumination light L1 may be applied to the other portions. This is because the first portion is primarily responsible for shielding unwanted light. In the following example, a circular shape is applied as the plan view shape of the exit aperture 4a.

[0040] In the example shown in Figure 2, the opening area of ​​the exit opening 4a at the second end opening 4ab is larger than the opening area of ​​the exit opening 4a at the first end opening 4aa. In other words, the inner circumferential surface 43c has a second portion that is located closer to the illumination space S1 than the first portion and has a larger opening area than the first portion. The second portion is, for example, the portion of the inner circumferential surface 43c that forms the second end opening 4ab.

[0041] The aperture area at the second end port 4ab of the exit aperture 4a can be set to be larger than the cross-sectional area of ​​the illumination light L1 at the same position as the second end port 4ab. For example, the inner diameter of the inner circumferential surface 43c at the second end port 4ab can be set to be larger than the optical diameter of the illumination light L1 at the same position as the second end port 4ab.

[0042] In the example shown in Figure 2, the inner surface 43c is inclined to move away from the central axis (here, axis AX1) of the exit aperture 4a as it approaches the illumination space S1. In other words, the inner surface 43c has a tapered shape that widens as it approaches the illumination space S1. The inner surface 43c may correspond to, for example, the side surface of a frustum. The inner surface 43c may have a shape that follows the side surface of, for example, a frustum of a cone or a frustum of a pyramidal pyramid. In other words, the inner surface 43c may be formed in a tapered shape where the aperture area widens as it approaches the illumination space S1.

[0043] The inner circumferential surface 43c of the emission aperture 43 is located outside the light distribution of the illumination light L1. Here, "outside the light distribution" may mean the area outside the hypothetical exclusion region R1 described later. Below, the shape of the exclusion region R1 in a cross-section containing the central axis of the emission aperture 4a (for example, Figure 2) will be described. In this cross-section, the exclusion region R1 is the area enclosed by the hypothetical edges R1a and R1b. Each of edges R1a and R1b passes through the first part of the inner circumferential surface 43c with the smallest aperture area (here, the part surrounding the first end aperture 4aa). The first part intersects the cross-section at the first point Pa and the second point Pb. The first point Pa and the second point Pb are located on opposite sides of the axis AX1. Edge R1a passes through the first point Pa, and edge R1b passes through the second point Pb. Sides R1a and R1b extend linearly such that the distance between them increases as they move toward the illumination space S1. In other words, side R1a slopes away from axis AX1 as it moves toward the illumination space S1, and side R1b also slopes away from axis AX1 as it moves toward the illumination space S1. The value of the taper angle θ3 formed by sides R1a and R1b is equal to the value of the beam angle θ1. In other words, sides R1a and R1b extend with the same taper angle θ3 as the beam angle θ1.

[0044] The inner circumferential surface 43c that forms the injection opening 4a is located outside the exclusion region R1. The exclusion region R1 itself does not include edges R1a and R1b. Therefore, a portion of the inner circumferential surface 43c may be located above at least one of edges R1a and R1b.

[0045] Alternatively, "outside the light distribution" may refer to an area outside of region R2 shown in Figure 1. Region R2 is, for example, the area within the exit aperture 4a where the peak value of the light intensity distribution of the illumination light L1 is e 2 This may also be a region enclosed by the outer edge of the illumination light L1 having 1 / 2 the luminous intensity.

[0046] Furthermore, in the example shown in Figure 1, the taper angle θ2 of the inner surface 43c is greater than the beam angle θ1. The difference between the taper angle θ2 and the beam angle θ1 may be, for example, 10 degrees or more. When the taper angle θ2 is, for example, 15 to 75 degrees, the beam angle θ1 may be 10 to 60 degrees.

[0047] As described above, the illumination light L1 travels while spreading at a beam angle θ1 on the illumination space S1 side of the image plane IS1. However, the inner circumferential surface 43c is located outside the beam distribution of the illumination light L1. For this reason, the illumination light L1 is unlikely to be incident on the inner circumferential surface 43c. In particular, in the example of Figure 1, the taper angle θ2 of the inner circumferential surface 43c of the exit aperture 4a is larger than the beam angle θ1, so the illumination light L1 is unlikely to be incident on the inner circumferential surface 43c. Therefore, reflection and scattering of the illumination light L1 at the inner circumferential surface 43c are unlikely to occur, and the reflected and scattered light is unlikely to be emitted into the illumination space S1. As a result, the uniformity of the illumination light L1 emitted into the illumination space S1 can be reduced, and the illumination device 1 can emit a more uniform illumination light L1 into the illumination space S1.

[0048] In the example shown in Figure 1, the housing 4 further includes a mounting portion 46. The mounting portion 46 is a component for attaching the lighting device 1 to an installation target. The installation target may be, for example, the ceiling of the lighting space S1. The mounting portion 46 contacts the installation target (e.g., the upper surface of the ceiling) and is fixed to the installation target by fixing members such as screws. In the example shown in Figure 1, the mounting portion 46 is located on the outer circumferential surface of the cylindrical portion 41. The mounting portion 46 may be located around the entire circumference of the outer circumferential surface of the cylindrical portion 41. In other words, the mounting portion 46 may have a ring-shaped form with the axis AX1 as its central axis. In the example shown in Figure 1, in a cross-section including the axis AX1, the mounting portion 46 has a right-angled triangular shape. The surface corresponding to the hypotenuse of the mounting portion 46 is inclined to approach the axis AX1 as it approaches the lighting space S1. This surface of the mounting portion 46 can contact the installation target.

[0049] Although the mounting portion 46 may also be included in the lighting device 1 according to other embodiments described later, the mounting portion 46 will be omitted in the following description of each lighting device 1.

[0050] <Second Embodiment> In the examples shown in Figures 1 and 2, the aperture area of ​​the exit aperture 4a increases continuously and monotonically as it approaches the lighting space S1. Specifically, the diameter of the exit aperture 4a increases proportionally as it approaches the lighting space S1. However, the lighting device 1 is not necessarily limited to this.

[0051] Figure 4 is a schematic diagram showing an example of the configuration of the lighting device 1 according to the second embodiment. Hereinafter, the lighting device 1 according to the second embodiment will be referred to as lighting device 1A. Lighting device 1A has the same configuration as lighting device 1 according to the first embodiment, except for the shape of the exit opening 4a of the exit opening 43. As shown in Figure 4, the opening area of ​​the exit opening 4a increases toward the lighting space S1, but increases in a stepped manner. In the example of Figure 4, the inner circumferential surface 43c of the exit opening 43 includes a first inner circumferential portion 431c and a second inner circumferential portion 432c. Both the first inner circumferential portion 431c and the second inner circumferential portion 432c are parts of the inner circumferential surface 43c that surround the central axis of the exit opening 4a. The second inner circumferential portion 432c is located closer to the lighting space S1 than the first inner circumferential portion 431c. The first inner circumference portion 431c forms the first aperture portion 4a1 of the exit aperture 4a on the lens optical system 3 side, and the second inner circumference portion 432c forms the second aperture portion 4a2 of the exit aperture 4a on the illumination space S1 side. The first aperture portion 4a1 and the second aperture portion 4a2 are continuous and constitute the exit aperture 4a. The first end 4aa of the exit aperture 4a corresponds to the end of the first aperture portion 4a1 on the lens optical system 3 side, and the second end 4ab of the exit aperture 4a corresponds to the end of the second aperture portion 4a2 on the illumination space S1 side.

[0052] As shown in Figure 4, the opening area of ​​the first opening 4a1 is smaller than the cross-sectional size of the internal space of the cylindrical portion 41. For example, the inner diameter of the first inner circumference portion 431c is smaller than the inner diameter of the cylindrical portion 41. The opening area of ​​the first opening 4a1 may be approximately constant regardless of its position. As shown in Figure 4, the opening area of ​​the exit opening 4a may be smallest in the first opening 4a1. The opening area of ​​the first opening 4a1 may be set to be larger than the cross-sectional area of ​​the illumination light L1 within the first opening 4a1. If the first opening 4a1 has a circular shape in plan view, the inner diameter of the first inner circumference portion 431c may be set to be larger than the optical diameter of the illumination light L1 within the first opening 4a1.

[0053] The plan view shape of the first aperture 4a1 may be circular, elliptical, or rectangular, as shown in Figure 3, for example. The plan view shape of the first aperture 4a1 may be the same as, or similar to, the shape of the illumination light L1 on the image plane IS1. This allows for a further reduction in the aperture area of ​​the first aperture 4a1 while suppressing the incidence of illumination light L1 on the first surface 43a of the exit aperture 43. As a result, unwanted light emitted into the illumination space S1 can be reduced, while the presence of the illumination device 1A can be reduced.

[0054] The opening area of ​​the second opening 4a2 at the end facing the first opening 4a1 is larger than the opening area of ​​the first opening 4a1. In other words, the opening area increases in a stepped manner before and after the boundary between the first opening 4a1 and the second opening 4a2.

[0055] In the example shown in Figure 4, the opening area of ​​the second opening 4a2 increases as it approaches the lighting space S1. Specifically, the second inner circumferential portion 432c is inclined to move away from the axis AX1 as it approaches the lighting space S1. In other words, the second inner circumferential portion 432c has a tapered shape that widens as it approaches the lighting space S1. The second inner circumferential portion 432c corresponds to, for example, the side surface of a frustum. The second inner circumferential portion 432c may have a shape that follows the side surface of, for example, a frustum of a cone or a frustum of a pyramidal pyramid. In other words, the second inner circumferential portion 432c may be formed in a tapered shape in which the opening area widens as it approaches the lighting space S1. In this case, the inner diameter of the second inner circumferential portion 432c increases proportionally as it approaches the lighting space S1.

[0056] In the example shown in Figure 5, the inner diameter of the first inner circumference portion 431c of the plate-shaped portion 431 is smaller than the minimum inner diameter of the second inner circumference portion 432c of the tip portion 432. Therefore, as viewed from the lens optical system 3, the plate-shaped portion 431 covers the tip portion 432.

[0057] The aperture area of ​​the second end port 4ab of the exit aperture 4a may be set to be larger than the cross-sectional area of ​​the illumination light L1 at the same position as the second end port 4ab. For example, the inner diameter of the second end port 4ab of the second inner circumference portion 432c may be set to be larger than the optical diameter of the illumination light L1 at the same position as the second end port 4ab. As shown in Figure 4, the taper angle θ4 of the second inner circumference portion 432c may be smaller than the beam angle θ1. The difference between the beam angle θ1 and the taper angle θ4 may be, for example, 10 degrees or more.

[0058] In the example shown in Figure 4, the taper angle θ2 of the side surface of a hypothetical frustum connecting the first portion of the inner surface 43c with the smallest aperture area and the portion with the largest aperture area is greater than the beam angle θ1.

[0059] In the example shown in Figure 4, the emission opening 43 includes a plate-like portion 431 and a tip portion 432, with the tip portion 432 located closer to the illumination space S1 than the plate-like portion 431. The first opening portion 4a1 is formed in the plate-like portion 431, and the second opening portion 4a2 is formed in the tip portion 432. That is, the first inner circumference portion 431c corresponds to the inner circumference surface of the plate-like portion 431, and the second inner circumference portion 432c corresponds to the inner circumference surface of the tip portion 432. The plate-like portion 431 and the tip portion 432 may be separate entities.

[0060] In the example shown in Figure 4, as described above, the minimum opening area of ​​the ejection opening 4a is the opening area of ​​the first opening portion 4a1. Therefore, the first portion of the inner circumferential surface 43c of the ejection opening 43 that has the minimum opening area corresponds to the first inner circumferential portion 431c. Furthermore, the second portion of the inner circumferential surface 43c that has a larger opening area than the first portion may correspond to, for example, the second inner circumferential portion 432c.

[0061] Figure 5 is an enlarged view showing an example of the configuration of the emission aperture 43 according to the second embodiment. In the second embodiment as well, the inner circumferential surface 43c of the emission aperture 43 is located outside the light distribution area. Here, "outside the light distribution area" may mean outside the exclusion region R1, as in the first embodiment. In the example of Figure 5, the sides R1a and R1b that define the exclusion region R1 pass through the end on the illumination space S1 side of the first part (first inner circumferential part 431c in Figure 5) where the aperture area is smallest. In Figure 5, the first inner circumferential part 431c appears as two line segments located on opposite sides of the axis AX1, and the ends of these line segments on the illumination space S1 side correspond to the first point Pa and the second point Pb, respectively. Side R1a passes through the first point Pa, and side R1b passes through the second point Pb. The value of the taper angle θ3 between side R1a and side R1b is equal to the value of the light distribution angle θ1, as in the first embodiment.

[0062] Alternatively, the "outside the light distribution area" may be outside the region R2, as in the first embodiment (see Figure 4).

[0063] In the lighting device 1A, the inner circumferential surface 43c of the emission aperture 43 is located outside the light distribution area, so the incidence of illumination light L1 onto the inner circumferential surface 43c can be suppressed. In particular, since the taper angle θ2 is larger than the light distribution angle θ1, the incidence of illumination light L1 onto the inner circumferential surface 43c can be suppressed more effectively.

[0064] Next, the thicknesses of the plate-like portion 431 and the tip portion 432 will be described. As shown in Figures 4 and 5, the thickness of the plate-like portion 431 may be less than the thickness of the tip portion 432. In other words, the thickness of the first opening portion 4a1 may be less than the thickness of the second opening portion 4a2. The thickness of the plate-like portion 431 may be, for example, less than half, less than one-tenth, or less than one-twentieth of the thickness of the tip portion 432. To give a specific numerical value for the thickness, the thickness of the plate-like portion 431 may be, for example, less than 2 mm, less than 1 mm, less than 0.5 mm, or less than 0.1 mm. As a specific example, the thickness of the plate-like portion 431 is about 50 μm. A plate-like portion 431 with such a small thickness can be said to have the shape of a film. The thickness of the tip portion 432 may be, for example, 5 mm or more, and as a specific example, it may be about 10 mm.

[0065] If the tip portion 432 is separate from the plate-like portion 431, the peripheral edge of the second inner circumference portion 432c of the tip portion 432 may be rounded. This peripheral edge is also a corner. Specifically, the peripheral edge 432a connecting the surface of the tip portion 432 on the plate-like portion 431 side to the second inner circumference portion 432c may be rounded. The radius of the rounding of the peripheral edge 432a can be set to, for example, several hundred μm or more. The thickness of the plate-like portion 431 may be smaller than the radius of the rounding of the peripheral edge 432a of the tip portion 432.

[0066] The manufacturing curvature formed on the peripheral edge 432a of the thick tip portion 432 is relatively large, so if unwanted light is incident on the peripheral edge 432a, reflection and scattering are likely to occur at the peripheral edge 432a. For example, in the first embodiment, manufacturing curvature may also be formed on the peripheral edge of the output opening 43 that forms the first end opening 4aa. If unwanted light is incident on this peripheral edge, reflection and scattering will occur over a relatively wide area at this peripheral edge. When the unwanted light reflected or scattered at this peripheral edge is emitted into the illumination space S1, it can cause unevenness in the illumination light L1 emitted into the illumination space S1. More noticeably, a person in the illumination space S1 may see the peripheral edge as glowing. This makes the illumination device 1 appear more prominent.

[0067] In contrast, in the second embodiment, the plate-like portion 431 covers the peripheral edge 432a of the tip portion 432 from the lens optical system 3 side (see Figure 5). Therefore, almost no unwanted light is incident on the peripheral edge 432a of the tip portion 432. Consequently, reflection and scattering at the peripheral edge 432a can be suppressed.

[0068] Furthermore, in the above example, since the plate-like portion 431 is thin, unwanted light is less likely to enter the first inner circumference portion 431c of the plate-like portion 431. Also, even if unwanted light does enter, because the plate-like portion 431 is thin, the area in which reflection and scattering occur in the first inner circumference portion 431c is very small. Therefore, it is possible to reduce unwanted light reflected from the plate-like portion 431 and emitted into the illumination space S1. Consequently, it is possible to reduce unevenness in the illumination light L1 emitted into the illumination space S1 and to suppress the increased presence of the illumination device 1A.

[0069] Furthermore, if the thickness of the tip portion 432 is large, the field of view angle φ1 can be reduced, as will be explained below (see Figure 4). The field of view angle φ1 here refers to the angle that indicates the range of the inner wall of the housing 4 that can be seen through the emission aperture 4a from the area Sa1 outside the area directly below the illumination device 1A in the illumination space S1. Specifically, the field of view angle φ1 is the angle formed by virtual lines VL1 and VL2 in a cross-section (for example, Figure 4) that includes the central axis of the emission aperture 4a (here, axis AX1). Virtual line VL1 is a straight line connecting point P1 and point P2. Point P1 is the intersection of the peripheral edge of the inner circumferential surface 43c of the emission aperture 43 on the illumination space S1 side and the cross-section. Point P2 is the point on the opposite side of axis AX1 from point P1 among the intersections of the peripheral edge of the inner circumferential surface 43c on the lens optical system 3 side and the cross-section. The virtual line VL1 corresponds to the line of sight from region Sa1 at the smallest elevation angle φ2 that allows the interior of the housing 4 to be seen. The virtual line VL2 is a straight line connecting point P1 and point P3. Point P3 is the point on the same side as point P1 with respect to axis AX1, where the peripheral edge of the first inner circumference portion 431c on the illumination space S1 side intersects with the cross section.

[0070] This field of view angle φ1 represents the range of the inner wall of the housing 4 that is visible through the emission aperture 4a from region Sa1, which is located outside the irradiation range of the illumination light L1 in the illumination space S1. Hereinafter, the range of the inner wall of the housing 4 sandwiched between virtual lines VL1 and VL2, which intersect at the field of view angle φ1, will be referred to as the field of view range. The larger the field of view angle φ1, the wider the field of view range. When unwanted light reflected or scattered by the inner wall of the housing 4 within the field of view range is emitted into the illumination space S1 through the emission aperture 4a, a person in region Sa1 may see the inner wall of the housing 4 as glowing. As a result, the presence of the illumination device 1A becomes more prominent. In other words, the wider the field of view range, the greater the presence of the illumination device 1A.

[0071] Figure 6 is a schematic diagram showing an example of a configuration obtained by omitting the plate-shaped portion 431 from the lighting device 1A, and Figure 7 is a schematic diagram showing an example of a configuration obtained by omitting the tip portion 432 from the lighting device 1A. In the example of Figure 6, since the plate-shaped portion 431 is not present, the opening area of ​​the first end port 4aa of the emission opening 4a is larger than that in Figure 4. As a result, the inclination of the imaginary line VL2 becomes steeper, and the inclination of the imaginary line VL1 becomes gentler. In other words, the angle between the imaginary line VL2 and axis AX1 becomes smaller, and the angle between the imaginary line VL1 and axis AX1 becomes larger. Therefore, the field of view angle φ1 becomes larger, and the field of view range becomes wider.

[0072] In the example in Figure 7, since the tip 432 is not present, the slope of the virtual line VL2 becomes even steeper, and the slope of the virtual line VL1 becomes even gentler. In the example in Figure 7, the virtual line VL2 is almost parallel to axis AX1, and the virtual line VL1 intersects axis AX1 at an angle closer to a right angle. As a result, the field of view angle φ1 becomes even larger, and the field of view range becomes even wider.

[0073] In contrast, the example in Figure 4 allows for a smaller viewing angle φ1 compared to Figures 6 and 7. This is because the thickness of the tip portion 432 is greater than that of the plate-like portion 431, allowing for a gentler virtual line VL1 and a steeper virtual line VL2, thereby reducing the viewing angle φ1. Consequently, the presence of the lighting device 1A can be appropriately reduced.

[0074] In Figure 1, described in the first embodiment, the virtual line VL2 is a line virtually extended from the inner circumferential surface 43c. Therefore, if the taper angle θ2 is the same, the virtual line VL2 does not depend on the thickness h2 of the exit aperture 4a. On the other hand, the virtual line VL1 becomes steeper as the thickness h2 of the exit aperture 4a increases. Therefore, if the thickness h2 of the exit aperture 4a is greater than, for example, the thickness of the base portion 42 or the shielding portion 44, the viewing angle φ1 can be appropriately reduced.

[0075] As shown in Figures 1 and 4, the virtual line VL2 does not have to intersect the lens optical system 3. In other words, the virtual line VL2 may intersect the inner wall of the housing 4 on the side of the exit aperture 4a that is closer to the lens optical system 3. In this case, a person in area Sa1 cannot see the lens optical system 3 inside the housing 4. Therefore, the presence of the illumination device 1A can be further reduced.

[0076] Figure 8 is a schematic diagram showing another example of the configuration of the lighting device 1 according to the second embodiment. The plate-shaped portion 431 is separate from the tip portion 432 and is located between the cylindrical portion 41 and the tip portion 432. The tip portion 432 is attached to the cylindrical portion 41 by a mounting portion 433, which will be described later, and the plate-shaped portion 431 is sandwiched between the cylindrical portion 41 and the tip portion 432. A more specific example of the emission opening 43 will be described below.

[0077] In the example shown in Figure 8, the ejection opening 43 further includes a mounting portion 433. For example, the mounting portion 433 has a cylindrical shape and is erected on the periphery of the tip portion 432. The tip portion 432 and the mounting portion 433 may be integrally constructed from the same material. The mounting portion 433 has, for example, a cylindrical shape, and its central axis substantially coincides with the central axis of the cylindrical portion 41 (here, axis AX1). The outer diameter of the tip portion 432 is larger than both the outer diameter of the plate portion 431 and the outer diameter of the cylindrical portion 41, and the mounting portion 433 is located outside the plate portion 431 and the cylindrical portion 41. That is, the inner circumferential surface of the mounting portion 433 faces the outer circumferential surface of the plate portion 431 and the outer circumferential surface of the cylindrical portion 41. By fixing the mounting portion 433 to the cylindrical portion 41, the ejection opening 43 is fixed to the cylindrical portion 41. For example, the mounting portion 433 may be fitted into the cylindrical portion 41. Alternatively, for example, screw threads (not shown) may be formed on the inner circumferential surface of the mounting portion 433 and the outer circumferential surface of the cylindrical portion 41, and the mounting portion 433 may be connected to the cylindrical portion 41 by a screw action.

[0078] The peripheral edge of the plate-shaped portion 431 may be in contact with the second peripheral edge of the cylindrical portion 41 on the illumination space S1 side, or it may be in contact with the surface of the tip portion 432 on the lens optical system 3 side. For example, when the mounting portion 433 and the tip portion 432 are connected to the cylindrical portion 41 by screw action or the like, when the mounting portion 433 and the tip portion 432 are rotated around the axis AX1 relative to the cylindrical portion 41 in the tightening direction, the tip portion 432 is pressed toward the plate-shaped portion 431. In other words, the peripheral edge of the plate-shaped portion 431 is pressed toward the cylindrical portion 41 and the tip portion 432. This pressing allows the plate-shaped portion 431 to be held more firmly.

[0079] In such a lighting device 1A, the assembly of the cylindrical portion 41 and the emission opening 43 is performed, for example, by a worker as follows: First, the worker places the plate portion 431 between the cylindrical portion 41 and the tip portion 432. Next, the worker attaches the mounting portion 433 to the cylindrical portion 41. For example, the tip portion 432 and the mounting portion 433 may be press-fitted into the cylindrical portion 41. Alternatively, the tip portion 432 and the mounting portion 433 may be rotated integrally with respect to the cylindrical portion 41 and fixed by screw action. By fixing the mounting portion 433 to the cylindrical portion 41, the plate portion 431 is held by the cylindrical portion 41 and the tip portion 432. Therefore, by fixing the mounting portion 433, both the plate portion 431 and the tip portion 432 can be attached to the cylindrical portion 41. Thus, the assembly work of the lighting device 1A can be made simpler.

[0080] <Third Embodiment> Figure 9 is a schematic diagram showing a first example of the configuration of the lighting device 1 according to the third embodiment. Hereinafter, the lighting device 1 in Figure 9 will be referred to as lighting device 1B. Lighting device 1B has the same configuration as lighting device 1 according to the first or second embodiment, except for the presence or absence of the uneven shape 5.

[0081] In the example shown in Figure 9, the inner circumferential surface 43c of the ejection opening 43 has an uneven shape 5. The uneven shape 5 has a shape in which recesses and protrusions are arranged alternately in a cross-section including the central axis of the ejection opening 4a (for example, Figure 9).

[0082] Figure 10 is an enlarged view showing an example of the inner circumferential surface 43c of the exit aperture 43. In the examples of Figures 9 and 10, the uneven surface 5 has a sawtooth shape, and each tooth of the sawtooth (i.e., the convex part) is formed by the surface 51 on the lens optical system 3 side (corresponding to the third surface) and the surface 52 on the illumination space S1 side (corresponding to the fourth surface). In the uneven surface 5, the surfaces 51 and 52 are alternately continuous. Such an uneven surface 5 may have a helical shape similar to a female screw, or it may have a shape in which a plurality of ring shapes are arranged in the direction along the axis AX1. The pitch of the uneven surface 5 is set to, for example, a few millimeters or less.

[0083] As shown in Figure 10, the length of surface 52 may be longer than the length of surface 51. Also, the angle that surface 52 makes with axis AX1 may be smaller than the angle that surface 51 makes with axis AX1. In the examples in Figures 9 and 10, surface 51 is approximately perpendicular to axis AX1.

[0084] Unwanted light can enter the inner circumferential surface 43c of the exit aperture 43 mainly from the lens optical system 3 side at an oblique angle (see Figure 10). The unwanted light enters surface 51 or surface 52.

[0085] Unwanted light incident on surface 51 may be reflected by surface 51 and incident on surface 52 directly above it. Unwanted light may undergo multiple reflections in the recess between surface 51 and surface 52 directly above it. Since the multiple reflections attenuate the unwanted light, the amount of unwanted light can be reduced. Unwanted light traveling towards the back of the recess (i.e., the boundary between surface 51 and surface 52 directly above it) is reflected and travels again to the opposite side of the recess. Since the gap between surface 51 and surface 52 widens obliquely toward the lens optical system 3 side, unwanted light may travel obliquely toward the lens optical system 3 side. In other words, unwanted light incident on surface 51 of the inner circumferential surface 43c obliquely from the lens optical system 3 side is reflected and returns again obliquely toward the lens optical system 3 side.

[0086] Furthermore, some of the unwanted light incident on surface 52 from the lens optical system 3 side at an oblique angle may be reflected by surface 52 and incident on surface 51 directly below it. The unwanted light incident on surface 51 similarly undergoes multiple reflections and travels to the back of the recess. Then, the unwanted light bounces off the back of the recess and travels to the opposite side. Since the gap between surface 51 and surface 52 widens obliquely toward the lens optical system 3 side, the unwanted light can still travel obliquely toward the lens optical system 3 side.

[0087] As described above, at least a portion of the unwanted light incident on the inner circumferential surface 43c of the emission aperture 43 can be reflected towards the lens optical system 3, thereby reducing the amount of unwanted light emitted into the illumination space S1. Consequently, the uniformity of the illumination light L1 emitted into the illumination space S1 can be reduced. In other words, the illumination device 1B can emit more uniform illumination light L1 into the illumination space S1.

[0088] The taper angle θ2 of the inner circumferential surface 43c having the uneven shape 5 may be, for example, the angle between virtual lines VL3 and VL4 in a cross-section including the axis AX1. Virtual lines VL3 and VL4 are located on opposite sides of the axis AX1 and may be straight lines connecting the tips of the protrusions of the uneven shape 5. The taper angle θ2 is greater than the beam angle θ1, as in the first embodiment.

[0089] Figure 11 is a schematic diagram showing a second example of the configuration of the lighting device 1 according to the third embodiment. Hereinafter, the lighting device 1 in Figure 11 will be referred to as lighting device 1C. Lighting device 1C has the same configuration as lighting device 1B except for the position of the uneven shape 5. In lighting device 1C, instead of the inner circumferential surface 43c of the emission opening 43, the first surface 43a of the emission opening 43 has the uneven shape 5.

[0090] The uneven shape 5 may be formed in the annular region surrounding the ejection opening 4a on the first surface 43a. The uneven shape 5 may also be formed around the entire circumference of the annular region. In a cross-section including the axis AX1 (for example, Figure 11), the uneven shape 5 has a shape in which recesses and protrusions are arranged side by side.

[0091] Figure 12 is an enlarged view of an example of the first surface 43a of the ejection opening 43. In the example of Figure 12, the uneven surface 5 has a sawtooth shape, and each tooth (i.e., convex part) of the sawtooth is formed by surface 53 and surface 54. In the uneven surface 5, surfaces 53 and 54 are alternately continuous. Such an uneven surface 5 may have a helical shape in plan view, or it may have a shape in which multiple ring shapes are arranged concentrically. The pitch of the uneven surface 5 is set to, for example, a few millimeters or less. As shown in Figure 12, the length of surface 51 may be equal to the length of surface 52. For example, surfaces 51 and 52 correspond to the hypotenuse of an isosceles triangle.

[0092] The protrusions of the uneven shape 5 do not necessarily have to extend along the circumferential direction centered on axis AX1. For example, the uneven shape 5 may have a dot-like shape in plan view. In other words, multiple protrusions may be arranged two-dimensionally. Furthermore, the cross-sectional shape of the protrusions or recesses does not necessarily have to be triangular, but may be any shape such as circular or elliptical.

[0093] When unwanted light enters the first surface 43a of the exit aperture 43, the unwanted light is reflected and scattered by the first surface 43a, which has an uneven shape 5. As a result, the unwanted light spreads more widely toward the lens optical system 3. Therefore, the unwanted light is more spatially uniform. In addition, the unwanted light is attenuated by repeated reflection and scattering inside the housing 4. Therefore, even if unwanted light reflected and scattered by the housing 4 is emitted from the exit aperture 4a into the illumination space S1, it is less likely to cause unevenness in the illumination light L1.

[0094] Furthermore, both the first surface 43a and the inner circumferential surface 43c of the injection opening 43 may have an uneven shape 5.

[0095] Figure 13 is a schematic diagram showing a third example of the configuration of the lighting device 1 according to the third embodiment. Hereinafter, the lighting device 1 in Figure 13 will be referred to as lighting device 1D. Lighting device 1D has the same configuration as lighting device 1 according to the first or second embodiment, except for the presence or absence of the reflection reduction unit 6. In lighting device 1D, the reflection reduction unit 6 is located. In the example in Figure 13, the reflection reduction unit 6 is located on the first surface 43a and the inner circumferential surface 43c of the emission opening 43. In other words, the surface of the reflection reduction unit 6 corresponds to the first surface 43a and the inner circumferential surface 43c. The reflection reduction unit 6 reduces the reflection of unwanted light.

[0096] The reflection reduction section 6 may include an anti-reflective coating having a low reflectivity for illumination light L1. In other words, the reflectivity of the first surface 43a and the inner circumferential surface 43c may be low. This reflectivity may be, for example, 50% or less, 40% or less, 20% or less, or 10% or less. The reflection reduction section 6 may have a low reflectivity over the entire wavelength range of illumination light L1, or it may have a low reflectivity at the peak wavelength. The reflectivity of the reflection reduction section 6 for illumination light L1 is, for example, lower than the reflectivity of the inner wall of the housing 4 where the reflection reduction section 6 is not located.

[0097] Such a reflection reduction portion 6 can be formed, for example, by performing a blackening treatment on the first surface 43a and the inner circumferential surface 43c of the ejection opening 43. As a specific example, the reflection reduction portion 6 can be formed by a blackening treatment such as chemical conversion treatment, plating, and painting. The blackening treatment may be a matte blackening treatment or a glossy blackening treatment. Such a reflection reduction portion 6 is made of a black material. This material may include, for example, at least one of a black metal, a black metal oxide film, and a black resin.

[0098] Alternatively, the reflection reduction section 6 may include a dielectric multilayer film. The dielectric multilayer film has, for example, a structure in which multiple dielectric thin films are stacked. As the dielectric, one or more materials from among titanium oxide (TiO2), SiO2, niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5), and magnesium fluoride (MgF2) may be used.

[0099] Alternatively, the reflection reduction section 6 may include flocked paper. For example, flocked paper may consist of a base material such as paper or cloth, and chemical fibers attached to the base material in an upright position. If black flocked paper is used, the reflection of unwanted light can be further suppressed compared to flocked paper of other colors.

[0100] The reflection reduction portion 6 may be formed around the entire circumference of the annular region surrounding the exit aperture 4a on the first surface 43a. The reflection reduction portion 6 can be formed over the entire surface of the first surface 43a. Alternatively, the reflection reduction portion 6 may be formed around the entire circumference of the inner circumferential surface 43c, for example, over the entire surface of the inner circumferential surface 43c.

[0101] In the example shown in Figure 12, the reflection reduction section 6 is located on both the first surface 43a and the inner circumferential surface 43c of the exit opening 43, but it may be located on at least one of them. Furthermore, the first surface 43a may have an uneven shape 5 and also have the reflection reduction section 6, and the inner circumferential surface 43c may have an uneven shape 5 and also have the reflection reduction section 6.

[0102] Figure 14 is a schematic diagram showing a fourth example of the configuration of the lighting device 1 according to the third embodiment. Hereinafter, the lighting device 1 in Figure 14 will be referred to as lighting device 1E. Lighting device 1E has the same configuration as lighting device 1A except for the presence or absence of the uneven shape 5. In the example of Figure 14, the second inner circumferential portion 432c of the tip portion 432 of the exit opening 43 has the uneven shape 5. The uneven shape 5 of the second inner circumferential portion 432c can be made up of surfaces 51 and 52, for example, similar to those in Figure 10. On the other hand, as shown in Figure 14, the first inner circumferential portion 431c of the plate-like portion 431 of the exit opening 43 does not have to have the uneven shape 5. This makes it easier to process the plate-like portion 431 and easier to manufacture the plate-like portion 431 thinly.

[0103] In the example shown in Figure 14, the first surface 43a of the plate-like portion 431 has an uneven shape 5. The uneven shape 5 of the first surface 43a can be composed of surfaces 53 and 54, for example, similar to those in Figure 12.

[0104] According to the lighting device 1E, since the second inner circumference portion 432c has an uneven shape 5, unwanted light emitted into the lighting space S1 can be reduced by the same action as the lighting device 1B. Also, since the first surface 43a has an uneven shape 5, unwanted light emitted into the lighting space S1 can be reduced by the same action as the lighting device 1C.

[0105] In the lighting device 1E, only one of the first surface 43a and the second inner circumference portion 432c of the emission opening 43 may have the uneven shape 5. Also, the first surface 43a may have a reflection reduction portion 6 together with the uneven shape 5, or in place of the uneven shape 5, similar to the lighting device 1D. Also, the second inner circumference portion 432c may have a reflection reduction portion 6 together with the uneven shape 5, or in place of the uneven shape 5, similar to the lighting device 1D.

[0106] As described above, lighting devices 1,1A to 1E have been described in detail, but the above description is illustrative in all respects, and lighting devices 1,1A to 1E are not limiting. It is understood that countless variations not illustrated can be envisioned without falling outside the scope of this disclosure. The components described in each of the above embodiments and variations can be combined or omitted as appropriate, as long as they do not contradict each other.

[0107] It goes without saying that all or part of each of the above embodiments and various modifications can be combined as appropriate and in a non-contradictory manner.

[0108] This disclosure includes the following:

[0109] In one embodiment, (1) the lighting device is a lighting device that emits illumination light into an external lighting space, and can comprise a housing having an opening that opens into the lighting space and in which no lens is located, a light source that emits the illumination light, and an optical system located inside the housing that forms an image of the illumination light from the light source and emits it from the opening at a predetermined beam angle, wherein the inner surface of the opening can have a first portion having the smallest opening area and a second portion located closer to the lighting space than the first portion and having a larger opening area than the opening area in the first portion, the illumination light can be imaged in the first portion, and the inner surface can be located outside the beam distribution of the illumination light.

[0110] (2) In the lighting device described in (1) above, the housing may have a first surface on which the first end of the opening on the optical system side is formed, and a second surface on which the second end of the opening on the lighting space side is formed, and at least one of the inner surface and the first surface may have an uneven shape.

[0111] (3) In the lighting device described in (2) above, in a cross-section including the central axis of the opening, at least one of the inner circumferential surface and the first surface may have the uneven shape.

[0112] (4) The lighting device according to (3) above, wherein the inner circumferential surface may have the uneven shape, the uneven shape may have a shape in which recesses and protrusions are arranged alternately in the cross section, the protrusions may have a third surface and a fourth surface on the lighting space side of the third surface, and in the cross section, the length of the fourth surface may be longer than the length of the third surface.

[0113] (5) In any one of the lighting devices described in (1) to (4) above, the housing may have a first surface on which the first end of the opening on the optical system side is formed, and a second surface on which the second end of the opening on the lighting space side is formed, and the reflectance of the illumination light of at least one of the inner surface and the first surface may be 50% or less.

[0114] (6) In the lighting device described in any one of (1) to (5) above, the inner circumferential surface may have a tapered shape that widens towards the lighting space, and the taper angle of the inner circumferential surface may be greater than the light distribution angle.

[0115] (7) In the lighting device described in any one of (1) to (5) above, the housing may include a plate-like portion having a first inner circumferential portion of the inner circumferential surface that forms a first opening portion of the opening including the first portion, and a tip portion having a second inner circumferential portion of the inner circumferential surface that forms a second opening portion of the opening that is closer to the lighting space than the first opening portion, and the opening area of ​​the opening may increase in a stepped manner before and after the boundary between the first opening portion and the second opening portion.

[0116] (8) In the lighting device described in (7) above, the thickness of the tip portion may be greater than the thickness of the plate-shaped portion.

[0117] (9) In the lighting device described in (7) or (8) above, the plate-shaped portion and the tip portion may be separate.

[0118] (10) In the lighting device described in (9) above, the plate-like portion may have a film-like shape.

[0119] (11) In the lighting device described in (10) above, the second inner circumference portion may have a tapered shape that widens towards the lighting space, the peripheral edge of the second inner circumference portion on the plate-like portion side may be rounded, and the thickness of the plate-like portion may be less than or equal to the radius of the rounding of the peripheral edge.

[0120] (12) In the lighting device described in any one of (7) to (11) above, the first inner circumference portion of the plate-shaped portion does not have to have an uneven shape, and the second inner circumference portion of the tip portion may have an uneven shape.

[0121] (13) In the lighting device described in any one of (7) to (12) above, the housing may further include a cylindrical portion for housing the optical system, and the plate portion may be held between the cylindrical portion and the tip portion. [Explanation of symbols]

[0122] 1. Lighting device 2 light source 3. Optical System (Lens Optical System) 4 cabinets 41 Cylindrical part 431 Plate-like part 43a 1st page 43b 2nd side 43c Inner surface 431c First inner circumference portion 432 Tip 432a Peripheral edge 432c Second inner circumference portion 4a aperture (output aperture) 4a1 1st opening part 4a2 2nd opening part 4aa 1st end port 4ab 2nd end port 5 Uneven shape 51 3rd side (side) 52 4th side (side) L1 illumination light S1 Lighting Space

Claims

1. A lighting device that emits illumination light into an external lighting space, A housing having an opening that opens into the aforementioned lighting space, and in which no lens is located at the opening, The aforementioned light source that emits illumination light, An optical system located inside the housing, which forms an image of the illumination light from the light source and emits it from the aperture at a predetermined beam angle. Equipped with, The inner circumferential surface of the opening is The first part has the smallest opening area, A second portion located closer to the lighting space than the first portion, and having an opening area larger than the opening area of ​​the first portion. It has, The illumination light is imaged in the first portion, The inner circumferential surface is located outside the light distribution area of ​​the illumination light, The aforementioned enclosure is A plate-like portion having a first inner circumferential portion of the inner circumferential surface, which forms a first opening portion including the first portion of the opening, A tip portion having a second inner circumferential portion of the inner circumferential surface, which forms a second opening portion of the opening that is closer to the lighting space than the first opening portion. Includes, A lighting device in which the opening area of ​​the opening increases in a stepped manner before and after the boundary between the first opening portion and the second opening portion.

2. A lighting device according to claim 1, The second inner circumference portion is inclined so as it approaches the lighting space that it moves away from the central axis of the opening, in this lighting device.

3. A lighting device according to claim 1 or claim 2, The aforementioned enclosure is The first surface on which the first end opening on the optical system side of the opening is formed, The second surface of the aforementioned opening, on the side of the lighting space, is formed on the second end and It has, A lighting device wherein at least one of the inner circumferential surface and the first surface has an uneven shape.

4. A lighting device according to claim 3, A lighting device in which, in a cross-section including the central axis of the opening, at least one of the inner circumferential surface and the first surface has the aforementioned uneven shape.

5. A lighting device according to claim 4, The inner circumferential surface has the aforementioned uneven shape, The aforementioned uneven shape has a cross-sectional shape in which recesses and protrusions are arranged alternately. The aforementioned protrusion has a third surface and a fourth surface that is closer to the illumination space than the third surface. In the cross-section, the length of the fourth surface is longer than the length of the third surface of the lighting device.

6. A lighting device according to claim 1 or claim 2, The aforementioned enclosure is The first surface on which the first end opening on the optical system side of the opening is formed, The second surface of the opening on the lighting space side is formed It has, A lighting device in which the reflectance of at least one of the inner surface and the first surface to the illumination light is 50% or less.

7. A lighting device according to claim 1 or claim 2, The inner circumferential surface has a tapered shape that widens towards the illumination space. A lighting device in which the taper angle of the inner surface is greater than the light distribution angle.

8. A lighting device according to claim 1 or claim 2, A lighting device in which the thickness of the tip portion is greater than the thickness of the plate-shaped portion.

9. A lighting device according to claim 1 or claim 2, A lighting device in which the plate-shaped part and the tip part are separate components.

10. A lighting device according to claim 9, The aforementioned plate-like portion has a film-like shape, and is a lighting device.

11. A lighting device according to claim 10, The second inner circumference portion has a tapered shape that widens towards the illumination space, The peripheral edge of the second inner circumference portion on the plate-like side is rounded. A lighting device in which the thickness of the plate-like portion is less than or equal to the radius of the curvature of the peripheral edge.

12. A lighting device according to claim 1 or claim 2, The first inner circumference portion of the plate-like part does not have an uneven shape. The second inner circumference portion of the tip of the lighting device has an uneven shape.

13. A lighting device according to claim 1 or claim 2, The housing further includes a cylindrical portion for housing the optical system, The plate-shaped portion is held between the cylindrical portion and the tip portion of the lighting device.

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