Light guide body and light guide body assembly

Abstract

A light guide body 100 is equipped with: a light incidence section 110 having a light incident surface 110a into which light is inputted in a -Z direction, reflective surfaces 112, 113 positioned in the -Z direction relative to the light incident surface, and a translucent part 11, and being configured in a manner such that the reflective surfaces reflect some of the light which is inputted from the light incident surface, and the translucent part allows a separate portion of the light inputted from the light incident surface and the reflected light which has been reflected by the reflective surfaces to pass therethrough; a light guide section 120 which has a light emission surface 120a positioned on the -Z side relative to the light incidence section, guides the reflected light in the Y-axis direction, and outputs the reflected light from the light emission surface; and a continuous part 131 provided in a manner such that the translucent part and the light guide section are connected, and a non-continuous part 132 provided in a manner such that the reflective surfaces and the light guide section are separated from one another, said continuous part 131 and non-continuous part 132 each being positioned at the boundary between the light incidence section and the light guide section. Some of the light inputted to the light incidence section is reflected by the reflective surfaces, and the reflected light is inputted into the light guide section from the translucent part via the continuous part and guided through the interior of the light guide section along the Y axis, making it possible for much of the light condensed by the light incidence section to be outputted from the light emission surface.

Description

Light guide and light guide assembly

[0001] The present invention relates to light guides and light guide assemblies.

[0002] In order to reduce carbon dioxide emissions, the use of renewable energy sources such as solar power generation is being promoted. However, the efficiency of light-to-electricity conversion is not necessarily high. Therefore, solar lighting systems have been developed to improve efficiency by collecting sunlight, directing it to another location, and using it for lighting without converting it to electricity. For example, Patent Document 1 discloses a lighting device that includes a light guide section extending parallel to an incident surface where light enters, multiple light-collecting elements, each of which has a light-collecting section that gradually tapers and is connected to the light guide section and has a reflecting surface at its end, multiple coupled waveguides that guide light from the multiple light-collecting elements via their respective reflecting surfaces, and an integrated waveguide connected to the multiple coupled waveguides and collects light. While the light-collecting elements in such lighting devices collect a large amount of light, the collected light leaks from the light-collecting elements when it travels backward, so the light-collecting efficiency is not necessarily high. Patent Document 1: JP 2008-251468 A General disclosure

[0003] (Item 1) A light guide that guides light input from a light input surface to a light output surface different from the light input surface and outputs the light may include a light input section having the light input surface configured to input the light from a first direction. The light guide may include a light guide section that is disposed closer to the light output surface than the light input section and guides the light in a second direction intersecting the first direction. The light guide may include a continuous section that connects the light input section and the light guide section and a discontinuous section that separates the light input section and the light guide section, respectively, disposed at the boundary between the light input section and the light guide section. The light input section may include a reflective surface that reflects a portion of the light input from the light input surface and a light-transmitting section that transmits another portion of the light input from the light input surface and reflected light reflected at the reflective surface. The light guide section may be configured to further guide the reflected light in the second direction. The continuous portion may be provided so that the light-transmitting portion of the light entrance portion and the light-guiding portion are continuous. The discontinuous portion may be provided so that the reflective surface of the light entrance portion and the light-guiding portion are spaced apart. (Item 2) An end of the discontinuous portion on the light-guiding portion side may be provided so as to extend at an incline with respect to the second direction. (Item 3) The reflective surface may include a first reflective surface and a second reflective surface located on one side and the other side of the light-transmitting portion with respect to the second direction and facing each other. (Item 4) The discontinuous portion may include a first discontinuous portion where the first reflective surface and the light-guiding portion are spaced apart, and a second discontinuous portion where the second reflective surface and the light-guiding portion are spaced apart. A first end of the first discontinuous portion on the light-guiding portion side and a second end of the second discontinuous portion on the light-guiding portion side may be provided so as to extend at an incline in different directions with respect to the second direction. (Item 5) The reflective surface may include a third reflective surface and a fourth reflective surface located on one side and the other side of the discontinuous portion in the second direction, respectively, facing each other. (Item 6) The third reflective surface and the fourth reflective surface may be inclined in different directions with respect to the second direction. (Item 7) The continuous portion and the discontinuous portion adjacent to the continuous portion may have different widths with respect to the second direction.(Item 8) The continuous portion and the discontinuous portion adjacent to the continuous portion may have approximately equal widths in the second direction. (Item 9) The interface between the discontinuous portion and the light-guiding portion at the boundary may form another reflective surface, reflecting the reflected light input from the light-transmitting portion to the light-guiding portion through the continuous portion and guiding it to the light-exiting surface. (Item 10) A plurality of the reflective surfaces and the light-transmitting portions may be arranged along the second direction within the light-entering portion, and a plurality of the continuous portions and the discontinuous portions may be arranged along the second direction at the boundary between the light-entering portion and the light-guiding portion. (Item 11) The plurality of discontinuous portions may have approximately equal widths in the second direction. (Item 12) The plurality of continuous portions may include a first-width continuous portion having a width of a first length in the second direction and a second-width continuous portion having a width of a second length in the second direction that is different from the first length. The first-width continuous portion and the second-width continuous portion may be arranged alternately. (Item 13) The light entrance portion may be formed to extend in the second direction, and the light entrance surface may be formed as a plane having a width in a third direction intersecting each of the first direction and the second direction. (Item 14) The light guiding portion may be formed to extend in the second direction. (Item 15) The end of the light guiding portion opposite the light entrance portion in the first direction may be formed as a plane. (Item 16) The continuous portion may be formed to extend in the third direction. (Item 17) The continuous portion may be arranged so that the third direction is approximately parallel to a plane including the sun's movement trajectory. (Item 18) The light guiding portion may be arranged so that the second direction is approximately perpendicular to a plane including the sun's movement trajectory. (Item 19) The light entrance surface may include a diffractive optical element disposed thereon or a surface treatment layer formed so that the refractive index changes continuously in the first direction. The light guide portion may be formed as a light guide member having a light incident surface and ... guide member and a light guide member having a light incident surface and a light guide member having a light guide member and a light guide member having a light guide member and a light guide member having a light guide member and a light guide member having a light guide member and a light guide member having a light guide member and a light guide member having a light guide member and a light guide member having a light guide member and a light guide member having a light guide member and a light guide member having a light guide member and a light guide member having a light guide member and a light guide member having a light guide member and a light guide member(Item 22) The light entrance portion and the light guide portion may be formed from the same material.

[0004] (Item 23) The light guide assembly may include two of the light guides stacked in the first direction. (Item 24) In the light guide assembly, the reflective surface of the lower light guide may be located below the light-transmitting portion of the upper light guide of the two light guides.

[0005] The above summary of the invention does not list all of the features of the present invention, and subcombinations of these features may also be inventions.

[0006] 6A shows the configuration of a light guide according to this embodiment. FIG. 6B shows the configuration of a light entrance section and a boundary section. FIG. 6C shows the collection of light input into the light guide by the light entrance section and the guiding of light by the light guiding section. FIG. 6D shows design variables for hollow spaces. FIG. 6E shows an example of the shape of a hollow space and design parameters related to the shape. FIG. 6F shows the guiding of light input into a light guide having polygonal hollow spaces. FIG. 6G shows an example of the arrangement and period of multiple hollow spaces, and design parameters related to the arrangement and period. FIG. 6G shows another design example of hollow spaces and design parameters. FIG. 6H shows the arrangement of a light guide and the light incidence angle φ associated with the diurnal orbit of the sun. FIG. 6H shows the light extraction efficiency for the incidence angle φ shown in FIG. 6A. FIG. 6H shows seasonal variations in the solar orbit and solar altitude. FIG. 6H shows the arrangement of a light guide and the solar altitude (noon angle) θ. FIG. 7B shows the light extraction efficiency for the solar altitude (incidence angle) θ. FIG. 7H shows an example of the arrangement of a light guide optimized for variations in solar altitude. FIG. 7I shows the configuration of a light guide according to a first modified example optimized for variations in solar altitude. FIG. 7J shows the definitions of the incidence angle and diffraction angle of light entering the input section from the light entrance surface. 16B shows the intensity versus diffraction angle of light diffracted after entering the light guide from the light entrance surface having a surface treatment layer. 16C shows the configuration of a second modified light guide optimized for variations in solar altitude. 16D shows the configuration of a third modified light guide optimized for the solar diurnal orbit in a side view. 16E shows the arrangement of a third modified light guide tilted with respect to the noon angle. 16F shows the configuration of a fourth modified light guide optimized for the solar diurnal orbit in a side view. 16G shows the configuration of a fifth modified light guide optimized for the solar diurnal orbit in a side view. 16H shows the flow of a first manufacturing method for a light guide. 16H shows the state of the interior of the mold after the mold and insert setting process in the first manufacturing method in a front view (cross section along reference line AA in FIG. 16B). 16H shows the state of the mold and insert setting process in the first manufacturing method in a side view (cross section along reference line BB in FIG. 16A). 16I shows the flow of resin in the molding process in the first manufacturing method. 16I shows the state of insert removal in the insert removal process in the first manufacturing method. 1 shows a flow chart of a second manufacturing method for a light guide; FIG. 2 shows a front view of the state inside the mold after the first mold setting process in the second manufacturing method; FIG. 3 shows the configuration of the light entrance portion molded in the light entrance portion molding process using the first mold in the second manufacturing method; FIG. 4 shows the configuration of the bottom surface and continuous portion of the light entrance portion; and FIG. 5 shows a front view of the state inside the mold after the second mold and nesting setting process in the second manufacturing method.10 shows a perspective view of a second mold and the state inside the mold after the insert setting process in the second manufacturing method. FIG. 11 shows a flow chart of a third manufacturing method for a light guide. FIG. 12 shows the configuration of a light inlet portion molded in a light inlet portion molding process in the third manufacturing method. FIG. 13 shows the configuration of a light guide portion molded in a light guide portion molding process in the third manufacturing method. FIG. 14 shows a state in which the light inlet portion and the light guide portion are welded in a welding process in the third manufacturing method. FIG. 15 shows a light guide assembly according to the present embodiment. FIG. 16 shows the principle of light collection by the light inlet portion and light guiding by the light guide portion of light input to the light guide assembly. FIG. 17 shows the configuration and light collection principle of a light guide assembly according to a modified example. FIG. 18 shows the configuration of a light guide according to a sixth modified example having a bottom structure. FIG. 19 shows light guiding of light input to a light guide according to the sixth modified example. FIG. 20 shows light guiding of light input to a light guide according to the sixth modified example. FIG. 21 shows light guiding of light input to a light guide according to the sixth modified example. FIG. 22 shows another example of a bottom structure. FIG. 23 shows yet another example of a bottom structure. 10 shows a light guide assembly formed using a light guide according to a sixth modified example.

[0007] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention as claimed. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0008] 1A and 1B respectively show the overall configuration of a light guide 100 according to this embodiment, as well as the configuration of a light entrance section 110 and a boundary section 130 between the light entrance section 110 and a light guide section 120. The light guide 100 is an optical device that efficiently collects light input from a light entrance surface 110a and outputs the collected light by guiding it to a light exit surface 120a different from the light entrance surface 110a without or with little leakage, and includes the light entrance section 110, the light guide section 120, and the boundary section 130. The light guide 100 as a whole has a generally plate-like shape that extends in two dimensions with the X-axis direction as its short side and the Y-axis direction as its long side, and has a thickness in the Z-axis direction.

[0009] The light entrance section 110 is an optical element that focuses light input in the input direction (the -Z direction in this embodiment) through the light entrance surface 110a, and includes a plurality of focusing elements 111. The plurality of focusing elements 111 are columnar members that extend in the X-axis direction and have an inverted, approximately isosceles trapezoidal cross section with a maximum width P in the Y-axis direction and a height d in the Z-axis direction. They are arranged in parallel in the Y-axis direction with the +Z sides of their Y-side surfaces (i.e., the +Y side surface and the -Y side surface) in contact with each other and the -Z sides spaced apart from each other. In this embodiment, the plurality of focusing elements 111 are integrally molded and connected to each other (however, for the sake of convenience in explaining the configuration and function of the light entrance section 110, the light entrance section 110 will be described as including a plurality of focusing elements 111). As a result, the light entrance section 110 is formed to extend in the Y-axis direction, and the +Z faces of the plurality of focusing elements 111 are connected to each other to form a planar light entrance surface 110a having a width in the X-axis direction. In this way, the light entrance surface 110a is provided so that light is input from the +Z side. In addition, two adjacent light-collecting elements 111 form a hollow space (also simply referred to as a space) 130s between them, which has a triangular cross section and extends in the X-axis direction.

[0010] The light-collecting elements 111 may be arranged in parallel and spaced apart from one another in the Y-axis direction. In this case, the +Z surfaces of the light-collecting elements 111 each function as an independent light-entering surface.

[0011] The light-collecting element 111 has reflective surfaces 112 and 113 and a light-transmitting portion 114 located below (in the -Z direction) the light-entering surface 110a. The light-collecting element 111 can be formed using a resin with a high refractive index, such as acrylic resin (refractive index 1.49) or polycarbonate resin (refractive index 1.58), or glass (for example, BK7 has a refractive index of 1.51 to 1.53). The boundary between the light-collecting element 111 and the space 130s, i.e., the ±Y side surfaces of the light-collecting element 111, function as reflective surfaces 112 and 113 that reflect a portion of the light input into the light-collecting element 111 via the light-entering surface 110a. Light entering the ±Y side surfaces from inside the light-collecting element 111 at an angle equal to or greater than the critical angle is totally reflected. The critical angle is approximately 42 degrees for acrylic resin, approximately 41 degrees for polycarbonate resin, and approximately 42 degrees for glass. Therefore, the ±Y side surfaces of the light-collecting element 111 are formed so that their normal lines form an angle equal to or greater than the critical angle with respect to the light input direction (the Z-axis direction in this embodiment). On the other hand, the portion of the light-collecting element 111 between the reflecting surfaces 112 and 113 functions as a light-transmitting portion 114 that transmits a portion of the light input from the light-entering surface 110a (the remaining portion that does not enter the reflecting surfaces 112 and 113 in this embodiment) and the reflected light reflected by the reflecting surfaces 112 and 113.

[0012] Reflecting surfaces 112 and 113 are positioned on the +Y and −Y sides of light-transmitting portion 114, respectively, and are arranged to face each other, so as to reflect light input from light-entering surface 110a toward light-transmitting portion 114. Here, reflecting surfaces 112 and 113 are formed linearly on the YZ cross section. Furthermore, in order to increase reflectivity, reflecting surfaces 112 and 113, i.e., the ±Y side surfaces of light-collecting element 111, may be mirror-finished. Furthermore, a reflective film may be provided using a metal or the like.

[0013] The light guide 120 is an optical element having a light output surface 120a located on the -Z side of the light input surface 110, and further guides light reflected by the reflecting surfaces 112 and 113 of the light input surface 110 in the +Y direction and / or the -Y direction, and outputs it from the light output surface 120a. The light guide 120 is formed in a plate shape extending in the Y-axis direction. Here, the width of the light guide 120 in the X-axis direction is equal to (or may be greater than) the width of the light input surface 110, the length in the Y-axis direction is greater than (or may be equal to) the length of the light input surface 110, and the thickness in the Z-axis direction is greater than the thickness of the light input surface 110 (this may be determined arbitrarily). The +Y side surface and / or the -Y side surface of the light guide 120 form the light output surface 120a that outputs light, and the -Z end surface 120b is formed flat, thereby functioning as a reflective surface that reflects light guided into the light guide 120 inward.

[0014] The light guiding section 120 can be formed from the same material as the light incident section 110 (light collecting element 111). To increase the reflectivity, the −Z end surface 120b of the light guiding section 120 may be mirror-finished. Also, a reflective film may be provided using a metal or the like.

[0015] In addition, on the light guide path from the light entrance surface 110a of the light entrance section 110 to the light exit surface 120a of the light guide section 120, the light entrance section 110 is arranged closer to the light entrance surface 110a than the light guide section 120, and the light guide section 120 is arranged closer to the light exit surface 120a than the light entrance section 110.

[0016] The boundary portion 130 is a portion located at the boundary between the light entrance portion 110 and the light guide portion 120 , and includes a continuous portion 131 and a discontinuous portion 132 .

[0017] The continuous portion 131 is provided so that the light-transmitting portion 114 of the light entrance portion 110 and the light guiding portion 120 are physically continuous with each other, and so that the light input from the light entrance surface 110a, i.e., the reflected light reflected by the reflecting surfaces 112 and 113 and the remaining light that did not enter the reflecting surfaces 112 and 113, is guided into the light guiding portion 120. The continuous portion 131 has an opening width A in the Y-axis direction and extends in the X-axis direction. The continuous portion 131 can be made of the same material as the light-collecting element 111. The continuous portion 131 may also be formed integrally with the light entrance portion 110 and / or the light guiding portion 120 as part thereof.

[0018] The discontinuous portions 132 are provided to separate the reflective surfaces 112, 113 of the light entrance portion 110 from the light guide portion 120, and are disposed adjacent to each of the ±Y sides of the continuous portion 131. The discontinuous portions 132 separate the light guide portion 120 from the light entrance portion 110 (the reflective surfaces 112, 113 formed on the ±Y side surfaces) to form a space 130s therebetween, whereby the interface between the discontinuous portions 132 and the light guide portion 120 functions as a reflective surface that reflects reflected light input from the light-transmitting portion 114 of the light entrance portion 110 through the continuous portion 131 to the light guide portion 120 and guides it to the light exit surface 120a. To increase reflectivity, the interface between the discontinuous portions 132 and the light guide portion 120, i.e., the +Z end face of the light guide portion 120 below the space 130s, may be mirror-finished. Alternatively, a reflective film may be provided using a metal or the like.

[0019] In this embodiment, the reflective surfaces 112, 113 and the light-transmitting portions 114 of the light entrance portion 110 are arranged in multiple locations along the Y-axis direction within the light entrance portion 110 by arranging the light-collecting elements 111 in parallel in the Y-axis direction to form the light entrance portion 110. Accordingly, multiple continuous portions 131 and multiple discontinuous portions 132 are provided at the boundary between the light entrance portion 110 and the light-guiding portion 120, and multiple continuous portions 131 and multiple discontinuous portions 132 are arranged alternately along the Y-axis direction. Here, the continuous portions 131 have a width A in the Y-axis direction (equal to the width of the light-transmitting portions 114) and are periodically arranged at a pitch P in the Y-axis direction. In this embodiment, the discontinuous portions 132 have a width approximately equal to that of the continuous portions 131 and are arranged adjacent to the continuous portions 131 or between the continuous portions 131. This reduces the aperture ratio A / P to approximately half. The continuous portion 131 and the discontinuous portion 132 adjacent thereto may have different widths in the Y-axis direction, and the aperture ratio A / P may be greater than or less than about half.

[0020] Here, the plurality of discontinuous portions 132, i.e., the plurality of discontinuous portions 132 arranged in the Y-axis direction via continuous portions 131, have the same or approximately the same width in the Y-axis direction. Alternatively, the plurality of continuous portions 131 may include first width continuous portions 131a having a width of a first length in the Y-axis direction and second width continuous portions 131b having a width of a second length different from the first length (see FIG. 4C ), which may be arranged alternately via the discontinuous portions 132.

[0021] As shown in FIG. 1B , the reflecting surfaces 112 and 113 of the light incident unit 110 reflect light incident from the light incident surface 110a toward the continuous portion 131. In particular, the reflecting surfaces 112 and 113 reflect light incident from a direction perpendicular to the light incident surface 110a (in this embodiment, the Z-axis direction) toward the continuous portion 131. Here, the light reflected by the reflecting surface 112 forms parallel light and passes through the continuous portion 131. That is, the light reflected at the +Z side of the reflecting surface 112 passes through the +Y side of the continuous portion 131, the light reflected at the center of the reflecting surface 112 passes through the center of the continuous portion 131, and the light reflected at the -Z side of the reflecting surface 112 passes through the -Y side of the continuous portion 131, and then enters the light guiding unit 120. Note that the light reflected by the reflecting surface 113 forms parallel light and enters the light guiding unit 120 in the same manner as the light reflected at the reflecting surface 112, except that the light travels in the opposite direction.

[0022] Note that the discontinuous portion 132 is disposed below the reflecting surfaces 112, 113 of the light entrance portion 110, and thus includes a discontinuous portion 132b separating the reflecting surface 112 from the light guiding portion 120 and a discontinuous portion 132a separating the reflecting surface 113 from the light guiding portion 120. Furthermore, by arranging the light-collecting elements 111 in parallel in the Y-axis direction within the light entrance portion 110, a space 130s having a triangular cross section as viewed in the Y-direction is formed therein by the Y-side surfaces of two adjacent light-collecting elements 111 and the discontinuous portion 132 (the +Z end portions of the light guiding portion 120), and the reflecting surfaces 112, 113 of the two adjacent light-collecting elements 111 face each other via the space 130s, and the discontinuous portions 132 located below each other are continuous. That is, the reflecting surfaces 112 and 113 (examples of the third and fourth reflecting surfaces) facing each other across the space 130s are located on the +Y end side and the -Y end side of the discontinuous portion 132 in the Y-axis direction, respectively, and are inclined in different directions with respect to the Y-axis direction (facing in the -Y, +Z direction and the +Y, +Z direction, respectively).

[0023] Furthermore, the end of the discontinuous portion 132 on the light-guiding portion 120 side (i.e., the interface with the discontinuous portion 132 of the light-guiding portion 120) is inclined with respect to the Y-axis direction. Here, the interfaces between the light-guiding portion 120 and each of the adjacent discontinuous portions 132 are inclined in different directions with respect to the Y-axis direction. The interface between the light-guiding portion 120 and the discontinuous portion 132 a is inclined in the clockwise direction with respect to the Y-axis, and the interface between the light-guiding portion 120 and the discontinuous portion 132 b is inclined in the counterclockwise direction with respect to the Y-axis. The discontinuous portions 132 arranged in the Y-axis direction include discontinuous portions 132 a and 132 b arranged alternately.

[0024] Furthermore, the opposing reflecting surfaces 112 and 113 of one focusing element 111 have the same inclination angle and in opposite directions relative to the Z axis. The inclination angles may be different for each of the adjacent focusing elements 111, or may alternate. The reflecting surfaces 112 and 113 facing each other across a space 130s between two adjacent focusing elements 111 have different inclination angles. The triangular cross sections of the multiple spaces 130s arranged in the Y-axis direction may be rotated alternately in different directions. Here, the rotation of the multiple spaces 130s refers to rotation around a reference axis parallel to the X-axis direction that passes through the center of the spaces 130s on the YZ plane. In this example, the left space 130sa is rotated clockwise and the right space 130sb is rotated counterclockwise relative to the pre-rotation state shown by the dotted line in the figure (i.e., the state in which the base of the triangle is parallel to the Y-axis direction). As a result, the spaces 130sa rotated clockwise and the spaces 130sb rotated counterclockwise are alternately arranged in the Y-axis direction.

[0025] When the plurality of spaces 130s are not rotated, the boundary 130 between the light entrance section 110 and the light guide section 120 forms a straight line extending in the Y-axis direction in the YZ plane, and the continuous section 131 and the discontinuous section 132 also form a continuous line in the YZ plane. When the plurality of spaces 130s are rotated, the boundary 130 bends repeatedly in the ±Z directions in the YZ plane to form a non-linear line extending in the Y-axis direction, and the continuous section 131 and the discontinuous section 132 also form a non-linear line in the YZ plane.

[0026] 2 shows the collection of light input into the light guide 100 by the light entrance section 110 and the light guided by the light guide section 120. As an example, the optical path of light that enters in the −Z direction from the light entrance surface 110a and is reflected by the reflecting surface 113 of the light entrance section 110 (the right-inclined surface of the space 130sa at the far left of the drawing) is shown. As described above, because the opening width A of the continuous section 131 is large (opening ratio A / P≈0.5), the light reflected by the reflecting surface 113 (reflected light) remains parallel, passes through the continuous section 131, and enters the light guide section 120. The reflected light that enters light-guiding section 120 is reflected by -Z end face 120b of light-guiding section 120 and returns in the +Z direction, then reflected at the interface with discontinuous section 132, in this case discontinuous section 132b below space 130sb, which is three spaces to the right of discontinuous section 132, or in this case space 130sa below reflecting surface 113, then reflected by -Z end face 120b of light-guiding section 120 and returns in the +Z direction, and then reflected again at the interface with discontinuous section 132b below space 130sb, which is two spaces to the right, then guided to the right within light-guiding section 120 and output from light output surface 120a. The interfaces between the discontinuous portions 132 (discontinuous portions 132a, 132b) arranged in the Y-axis direction and the light-guiding portion 120 are alternately inclined in different directions, and further the reflecting surfaces 112, 113 of the light-collecting elements 111 arranged in the Y-axis direction have alternately different inclination angles (absolute values ​​of the inclination angles with respect to the Z-axis), so that light reflected by the reflecting surface 113 is reflected at the interface of the same discontinuous portion 132 (discontinuous portion 132b in this example) and guided through the light-guiding portion 120. Note that the inclination angles of the discontinuous portions 132a, 132b and / or the inclination angles of the reflecting surfaces 112, 113 are determined so that the light that has entered the light-guiding portion 120 from the light-collecting element 111 does not leak through the light-transmitting portion 114 of a different light-collecting element 111 in the +Z direction of the light guide 100, i.e., so that the light is reflected at the interfaces of the multiple discontinuous portions 132.

[0027] 3 shows design variables for the hollow space 130s, particularly those that are important for maximizing the guided distance of light entering the light guide body 100. The design variables are grouped into three groups: shape, arrangement, and period.

[0028] The group of shape variables includes design variables related to the cross-sectional shape of the space 130s as viewed in the X direction. Here, two shapes, a polygon and a non-isosceles triangle, are adopted as the main shapes of the space 130s. The design variables for the polygon include adding tangent points to define a polygon, using a triangle as the basic shape. For example, adding one tangent point to the basic shape derives a quadrilateral shape (a wedge shape in this example). The design variables for the non-isosceles triangle include the base inclination and the left-right angle difference. The base inclination includes inclining the bottom surface (-Z plane) of the space 130s, i.e., the base of the cross-sectional shape as viewed in the X direction. For example, a deformed triangle can be derived by inclining the base of the triangle, which is the basic shape, downward and to the right. The left-right angle difference includes setting a difference in the inclination angle of the left and right hypotenuses (i.e., the reflecting surfaces 112 and 113) of the triangle, which is the basic shape. For example, a triangular shape extending to the right can be derived by making the angle of the right hypotenuse relative to the base smaller than that of the left hypotenuse.

[0029] 4A shows an example of the shape of hollow space 130s and design parameters related to the shape. By adding a contact point, one contact point is added to the base of the triangular basic shape to derive a quadrangle. The inclination of the base determines the slope of the two bases (left discontinuous portion 132c and left discontinuous portion 132f of discontinuous portion 132), i.e., the lower rear slope angle Bb and the lower front slope angle Bf. The difference between the left and right angles determines the slope of the two oblique sides (reflecting surfaces 112 and 113), i.e., the upper rear slope angle Ub and the upper front slope angle Uf.

[0030] FIG. 4B shows the light guide of light S input into the light guide 100 having polygonal hollow spaces 130s. In this example, spaces 130s having the diamond-shaped cross section shown in FIG. 4A are arranged at equal intervals in the Y-axis direction. Light S enters the light entrance section 110 through the light entrance surface 110a and enters the right oblique side of the first space 130s (i.e., the reflecting surface 113). The light S is reflected by the reflecting surface 113 and enters the light guide section 120 through the continuous section 131. The light S is then reflected by the bottom surface of the light guide section 120 and travels toward the bottom surface of the third space 130s. Here, the bottom surface of the space 130s includes two surfaces (left discontinuous portions 132c and 132f shown in FIG. 4A) facing in different directions, causing the light S to branch into two lights Sc and Sf. Light Sc is reflected by the bottom surface of light-guiding unit 120 at a small angle with respect to the Z-axis direction and heads toward the bottom surface of adjacent space 130s, where it is reflected again and guided in the +Y direction within light-guiding unit 120. Light Sf is reflected by the bottom surface of light-guiding unit 120 at a large angle and guided in the +Y direction within light-guiding unit 120. In this way, by appropriately branching the light and reflecting each of the branched light beams in an appropriate direction at the bottom surface of space 130s, it is possible to increase the light-guiding distance in the Y direction within light-guiding unit 120.

[0031] The group of placement variables includes design variables related to the placement of the spaces 130s in the Y-axis direction. Here, variable pitch and offset are adopted as placement variables for the spaces 130s. The variable pitch design variables include determining the width (texture width Tw in FIG. 4A ) of the bottom surfaces (discontinuous portions 132) of the spaces 130s in the Y-axis direction, and making the width of the gap (continuous portion 131) between two spaces 130s equal or different from the width of the bottom surfaces. For example, a dense arrangement of the spaces 130s is derived by making the gap between the two spaces 130s smaller than the width of the bottom surfaces. The offset design variables include vertical movement and light reflection position. The vertical movement design coefficient includes offsetting some spaces 130s among the multiple spaces 130s arranged in the Y-axis direction upward (+Z direction) or downward (-Z direction) relative to the other spaces 130s. For example, a placement is derived in which the right space is offset upward relative to the left space 130s. The design variables for the light ray reflection position include the position of the light ray incident on the bottom surface of the space 130s. For example, a configuration is derived in which the incident position of the light ray is shifted from the center of the bottom surface of the space 130s to the right of the center.

[0032] The group of periodic variables includes design variables related to the arrangement of the spaces 130s in the Y-axis direction. Here, irregular shapes are included as periodic variables of the spaces 130s. The design variables for irregular shapes include making the cross-sectional shapes of some of the spaces 130s, among the multiple spaces 130s arranged in the Y-axis direction, different from the cross-sectional shapes of the other spaces 130s. For example, an arrangement is derived in which spaces 130s having equilateral triangular cross sections and spaces 130s having triangular cross sections extending to the right are alternately arranged in the Y-axis direction.

[0033] 4C shows an example of the arrangement and period of the plurality of hollow spaces 130s, as well as design parameters related to the arrangement and period. The design parameters for the arrangement are shown as an example of the light guide path of light SA entering the right hypotenuse (reflecting surface 113) of space 130sa. Here, no contact points are added (triangular cross section), and the base of the triangular cross section is tilted diagonally downward to the left (-Y, -Z direction) or diagonally downward to the right (+Y, -Z direction) due to the base inclination. An angle difference is provided between the left and right hypotenuses (reflecting surfaces 112, 113). The shape and period of space 130s are such that, due to the irregular shape, spaces 130sa whose base is tilted diagonally downward to the left and spaces 130sb whose base is tilted diagonally downward to the right are alternately arranged in the Y-axis direction. In addition, the variable pitch determines the texture width Tw (see FIG. 4A ) of the bottom surfaces (discontinuous portions 132) of the spaces 130sa and 130sb in the Y-axis direction, the propagation ray projection width Sw (width of the continuous portions 131), the arrangement pitch (i.e., texture pitch) Tp of the spaces 130sa and 130sb by the variable pitch, the arrangement pitch deviation Bs between the spaces 130sa and 130sb, the height (i.e., texture height) of the spaces 130sa and 130sb by vertical movement, the initial deviation amount Sp0 of the propagation ray from the light ray reflection position, the propagation ray pitches Sp1, Sp2, ... which are the pitches of the reflection positions of the light rays on the interfaces with the light entrance portion 110 and the light guide portion 120, and the propagation ray angles Ts1, Ts2, ... which are the reflection angles of the light rays at the bottom surfaces of the spaces 130sa and 130sb.

[0034] 5 shows another design example and design parameters for the hollow space 130s. If the cross-sectional shape of the space 130s is triangular (without adding a contact point) and the base is tilted by inclining the base, the texture width Tw increases, which in turn reduces the propagation ray projection width Sw (the width of the continuous portion 131) or increases the texture pitch Tp, making it difficult to determine optimal design parameters. In such a case, by adding a contact point to form a square shape and tilting the base to, for example, set the lower rear slope angle Bb to 90 degrees, the base can be tilted without changing the texture width Tw, propagation ray projection width Sw, or texture pitch Tp.

[0035] 6A shows the arrangement of the light guide 100 and the incident angle φ of light accompanying the diurnal orbit of the sun. The light guide 100 is arranged so that the extension direction of the continuous portion 131 (i.e., the X-axis direction) is approximately parallel to a plane (movement trajectory plane) 99 containing the movement trajectory of the sun accompanying the diurnal orbit, and so that the normal direction of the light incident surface 110a is approximately parallel to the movement trajectory plane 99, i.e., so that the light collecting element 111 faces approximately parallel to the movement trajectory plane 99. The incident angle φ of light is determined based on the normal direction of the light incident surface 110a. Here, the movement trajectory plane 99 of the sun is the plane formed by the trajectory of the sun's orbital motion.

[0036] FIG. 6B shows the light extraction efficiency of the light guide 100 for the incident angle φ shown in FIG. 6A. The extraction efficiency can be analyzed using a so-called light ray simulation and is calculated by dividing the amount of light output from the light output surface 120a by the amount of light input to the light input surface 110a. When the incident angle φ is zero (normal incidence on the light input surface 110a), most of the light entering the light input section 110 via the light input surface 110a is guided within the light guide section 120 and output from the light output surface 120a. However, when the incident angle exceeds 20 degrees, the extraction efficiency gradually decreases, reaching almost zero at an incident angle of 80 degrees. It can be seen that a high extraction efficiency can be achieved at least within the incident angle range of 0 to 40 degrees, i.e., during long periods of sunlight.

[0037] Figure 7A shows the seasonal variations in the sun's diurnal orbit and solar altitude (noon altitude). The sun rises in the east of the horizon, reaches its zenith, and sets in the west due to its diurnal motion. Here, the diurnal orbit changes depending on the season, with the sun's altitude being highest at the summer solstice and lowest at the winter solstice.

[0038] 7B shows the arrangement of the light guide 100 and the solar altitude (also called the noon angle) θ. The light guide 100 is arranged so that the arrangement direction of the spaces 130s or the continuous portions 131 (i.e., the Y-axis direction) is approximately parallel to the north-south plane 98 that determines the solar altitude, and so that the normal direction of the light incident surface 110a is approximately parallel to the north-south plane 98, i.e., so that the light-collecting elements 111 are oriented vertically. The incident angle θ of light is determined based on the normal direction of the light incident surface 110a.

[0039] 7C shows the light extraction efficiency versus the solar altitude (incidence angle) θ shown in FIG. 7B . The extraction efficiency can be analyzed using a so-called ray simulation and is calculated by dividing the amount of light output from the light output surface 120a by the amount of light input to the light input surface 110a. When the incident angle θ is zero (normal incidence on the light input surface 110a), most of the light entering the light input section 110 via the light input surface 110a is guided through the light guide section 120 and output from the light output surface 120a. However, as the incident angle increases even slightly (exceeding approximately 3 degrees), the extraction efficiency drops sharply, reaching a minimum at an incident angle of approximately 10 degrees.

[0040] FIG. 8 shows an example of the arrangement of the light guide 100 optimized for variations in solar altitude. The light guide 100 is positioned so that the light guiding direction (i.e., the Y-axis direction) of the light guide section 120 is substantially perpendicular to the plane (movement trajectory plane 99 in FIG. 6A ) containing the sun's movement trajectory (movement trajectory associated with diurnal motion). That is, depending on the solar noon altitude, the light guide 100 is tilted by an angle θ′ so that the normal direction of the light incident surface 110a is within a range of approximately −3 to 3 degrees of the solar altitude. This brings the incident angle θ of the light S within a range of −3 to 3 degrees, maximizing the light extraction efficiency. The inclination of the light guide 100 may be adjusted multiple times throughout the year, for example, at four times a year, such as the vernal equinox, summer solstice, autumnal equinox, and winter solstice, to ensure that the normal direction of the light incident surface 110a is substantially aligned with the solar altitude.

[0041] FIG. 9 shows the configuration of a light guide 100d1 according to a first modified example, which is optimized for variations in solar altitude. The light guide 100d1 has a light guide section 120d1 whose thickness (thickness in the Z-axis direction) increases in the +Y direction. The light guide section 120d1 has a generally right-angled triangular shape in front view, with a top surface inclined at an angle θ' with respect to the Y-axis direction and a bottom surface parallel to the horizontal. The light entrance section 110 is disposed on the top surface of the light guide section 120. This allows the light guide 100 to be installed on a horizontal plane while the light entrance section 110 is inclined approximately equal to the solar altitude, thereby maximizing the light extraction efficiency, similar to the light guide 100 shown in FIG. 8.

[0042] The light entrance surface 110a of the entrance portion 110 may be surface-treated so that light from a wide range of angles enters the light entrance portion 110 approximately perpendicularly. A surface-treated surface treatment layer 110b is provided on the light entrance surface 110a. The surface treatment layer 110b includes, for example, a diffractive optical element or a moth-eye structure. The diffractive optical element may be, for example, a diffractive element in which a frustum-shaped micropattern having a structure or period of 100 nm or more and 10 μm or less extending in the Z-axis direction is arranged in the XY direction, or an oblique grating formed by arranging plate-shaped gratings inclined with respect to the Z-axis direction with their longitudinal axes aligned in the X-axis direction in the Y-axis direction. The moth-eye structure is a structure formed by arranging microscopic protrusions having a structure of 100 nm or more and 10 μm or less extending in the Z-axis direction in the XY direction, so that the refractive index changes continuously in the Z-axis direction.

[0043] 10A shows the definitions of the angle of incidence θ and the angle of diffraction θ1 of light S entering the light entrance section 110 from the light entrance surface 110a. The angle of incidence θ of light S is determined by the angle with respect to the normal direction (shown by the dashed line) of the light entrance surface 110a. When light S enters the light entrance section 110, which has a different refractive index from the air layer, it is diffracted by passing through the surface treatment layer 110b. The angle of diffraction θ1 is also determined by the angle with respect to the normal direction (shown by the dashed line) of the light entrance surface 110a. Note that if the surface treatment layer 110b is not provided on the light entrance surface 110a, the light will be refracted when it enters the light entrance section 110.

[0044] FIG. 10B shows the transmittance versus diffraction angle θ1 of light diffracted from the light incident surface 110a having the surface treatment layer 110b into the light incident section 110. The numbers in the figure indicate the diffraction order. Here, as an example, the surface treatment layer 110b employs a diffractive optical element having an array of frustum-shaped micropatterns with a structure or periodicity of 100 nm or more and 10 μm or less. Light S is diffracted upon entering the surface treatment layer 110b, with the zeroth to −8th order diffracted light beams spreading within an angular range of −60 to 40 degrees. Here, the −2nd, −4th, −6th, and −8th order diffracted light beams spreading with high transmittance within an angular range of −20 to 20 degrees. Therefore, by providing the surface treatment layer 110b on the light incident surface 110a and forming the surface treatment layer 110b so that the diffracted light (for example, -2nd, -4th, -6th, and -8th order diffracted light) relative to the solar altitude is concentrated within this range of diffraction angle θ1 and is guided in the Z-axis direction, the light can be guided in the Y-axis direction within the light guide 100, thereby improving the extraction efficiency.

[0045] FIG. 11 shows the configuration of a light guide 100d2 according to a second modification, which is optimized for variations in solar altitude. The light guide 100d2 includes a surface treatment layer 110b formed on the light entrance surface 110a. The surface treatment layer 110b may be, for example, a diffractive optical element having a trapezoidal micropattern with a structure or period of 100 nm or more and 10 μm or less, arranged in the X and Y directions. By designing the micropattern so that when light is incident at an incident angle θ in the YZ plane, most of the diffracted light is diffracted at a diffraction angle of approximately zero or within a diffraction angle range near zero. This allows most of the light S entering the light entrance surface 110a at a noon angle (incident angle θ) to be directed in the Z-axis direction within the light entrance section 110 and guided to the light guide section 120.

[0046] FIG. 12 shows a side view of a light guide 100d3 according to a third modification, which is optimized for the diurnal orbit of the sun. The light guide 100d3 includes a surface treatment layer 110b formed on the light entrance surface 110a. The surface treatment layer 110b may be, for example, a diffractive optical element with a frustum-shaped micropattern arranged in the XY direction. By designing the micropattern so that when light is incident at an incident angle φ in the XZ plane, most of the diffracted light is diffracted at a diffraction angle of approximately zero or within a diffraction angle range near zero, most of the light S entering the light entrance surface 110a at the incident angle φ can be directed in the Z-axis direction within the light entrance section 110 and guided to the light guide section 120.

[0047] 13, the light guide 100 may be tilted around the Y axis so that light enters the light entrance surface 110a at an incident angle φ relative to the meridian altitude. This allows strong light from the sun at meridian to enter the light entrance surface 110a, maximizing the amount of light guided to the light guide section 120.

[0048] 10B , it can be seen that the −3rd-order diffracted light, as well as the −2nd- and −8th-order diffracted light, spreads with high transmittance within an angular range of −50 to −20 degrees. Therefore, by providing a surface treatment layer 110b on the light incident surface 110a and forming the surface treatment layer 110b so that diffracted light (e.g., −3rd-order diffracted light) is concentrated within this diffraction angle θ1 range relative to the diurnal altitude of the sun and is guided in the Z-axis direction, the light can be guided in the Y-axis direction within the light guide 100, thereby improving the extraction efficiency. For example, the light guide 100 having the surface treatment layer 110b provided on the light incident surface 110a can be positioned so that the intersection line between the plane containing the sun's movement trajectory (the movement trajectory plane 99 in FIG. 6A ) and the light incident surface 110a is inclined with respect to the horizontal.

[0049] 14A and 14B show side views of the fourth and fifth modified light guides 100d4 and 100d5, which are optimized for the diurnal orbit of the sun. Each of the light guides 100d4 and 100d5 includes a light entrance section 110 having a light entrance surface 110a that is inclined about the Y axis relative to a light guide section 120 that extends in the X and Y directions.

[0050] The light entrance section 110 of the light guide 100d4 has an inverted W-shaped light entrance surface 110a, which includes two inclined surfaces facing the -X and +Z directions and two inclined surfaces facing the +X and +Z directions in side view. A surface treatment layer 110b may be provided on the light entrance surface 110a, including a diffractive optical element in which a truncated cone-shaped micropattern having a structure or period of 100 nm or more and 10 μm or less is arranged in the XY direction. By designing the micropattern so that when light enters an inclined surface inclined at an angle φ' in the -X and +Z directions with respect to the vertical axis in the XZ plane, most of the diffracted light is diffracted in a diffraction angle range approximately in the Z-axis direction or near the Z-axis. This allows most of the light S entering the light entrance surface 110a to be directed in the Z-axis direction within the light entrance section 110 and guided to the light guide section 120. Furthermore, due to the symmetry of the diffractive optical element, even when light enters an inclined surface that is inclined in the +X and +Z directions in the opposite direction to the initial direction, most of the light S that enters the light entrance surface 110a can be directed in the Z-axis direction within the light entrance section 110 and guided to the light guide section 120.

[0051] The light entrance section 110 of the light guide 100d5 has a sawtooth-shaped light entrance surface 110a including three inclined surfaces facing the -X and +Z directions in a side view. A surface treatment layer 110b including, for example, a diffractive optical element with a frustum-shaped micropattern arranged in the XY direction may be provided on the light entrance surface 110a. By designing the micropattern so that when light enters an inclined surface inclined in the -X and +Z directions by an angle φ' with respect to the vertical axis in the XZ plane, most of the diffracted light is diffracted in a diffraction angle range approximately along the Z axis or near the Z axis, most of the light S entering the light entrance surface 110a can be directed along the Z axis within the light entrance section 110 and guided to the light guide section 120. The light entrance surface 110a is not limited to three inclined surfaces, and may include one, two, four, or more inclined surfaces.

[0052] 15 shows a first manufacturing method flow S100 for the light guide 100. In this embodiment, as an example, acrylic resin is used as the molding material for the light guide 100. In other words, the light entrance section 110 and the light guide section 120 are formed from the same material.

[0053] In step S101, molds 151 and 152 and multiple inserts 153 are set. Figures 16A and 16B show the interiors of molds 151 and 152 from a front view (along reference line AA in Figure 16B) and a side view (along reference line BB in Figure 16A), respectively. Mold 151 is a metal mold for forming light entrance section 110 and includes an internal space sized and shaped to accommodate light entrance section 110 and multiple inserts 153. Mold 152 is a metal mold for forming light guiding section 120 and includes an internal space sized and shaped to accommodate light guiding section 120. Multiple inserts 153 are metal molds for forming spaces 130s in light entrance section 110 (between multiple light-collecting elements 111), and are solid columns with approximately isosceles triangular cross-sectional shapes.

[0054] The mold 152 is placed with its internal space facing the +Z direction, multiple nesting pieces 153 are arranged on the mold 152 in the Y-axis direction so as to straddle the internal space of the mold 152 in the X-axis direction, and the mold 151 is placed over the mold 152 with its internal space facing the -Z direction. As a result, an internal space 150s is formed between the molds 151 and 152, separated vertically by the multiple nesting pieces 153 except for a portion.

[0055] In step S102, acrylic resin is injected into the molds 151 and 152 to form the light guide 100. Fig. 16C shows the flow of resin inside the molds 151 and 152. The resin is injected downward through a through-hole (not shown) in the mold 152 and fills the interior space 150s in the direction indicated by the black arrow, filling upward through the gaps between the multiple inserts 153. After a certain period of time has passed and the resin has cooled, the process moves to the next step.

[0056] In step S103, mold 151 is pulled in the +Z direction to open the mold, thereby exposing light entrance section 110 on mold 152 with light guiding section 120 fitted in the internal space of mold 152, as shown in Fig. 16D.

[0057] In step S104, the plurality of core dies 153 are pulled out. Fig. 16D shows the state in which the plurality of core dies 153 are pulled out from the light guide 100. The plurality of core dies 153 are pulled out in the direction of the outline arrow (+X direction). Note that the plurality of core dies 153 may be formed in a tapered shape in which the +X end is narrower than the -X end, so that they can be easily pulled out from the light guide 100.

[0058] In step S105, the light guide 100 is removed from the mold 152. This results in the light guide 100 shown in FIG. 1A.

[0059] In step S106, the molds 151 and 152 and the plurality of inserts 153 are cleaned, and the flow then ends. By repeating steps S101 to S106, a plurality of light guide bodies 1 can be manufactured.

[0060] 17 shows a second manufacturing method flow S200 for the light guide 100. In this embodiment, as an example, acrylic resin is used as the molding material for the light guide 100. In other words, the light entrance section 110 and the light guide section 120 are formed from the same material.

[0061] In step S201, molds 161 and 162 are set. FIG. 18A shows the interior of molds 161 and 162 as viewed from the front (as viewed in the X-axis direction). Molds 161 and 162 are a pair of metal molds for forming the light entrance section 110. Mold 161 includes an internal space having a size and shape capable of accommodating light entrance section 110. Mold 162 has multiple protruding edges 162a that protrude from the top surface in the +Z direction and are aligned in the Y-axis direction. The multiple protruding edges 162a are structured to form spaces 130s in the light entrance section 110 (between the multiple light-collecting elements 111), and are formed to have a substantially isosceles triangular cross-sectional shape extending in the X-axis direction.

[0062] The mold 162 is placed with its multiple protruding sides 162a facing in the +Z direction, and the mold 161 is placed over the mold 162 with its internal space facing in the -Z direction to accommodate the protruding sides 162a. This forms an internal space 161s between the molds 161 and 162.

[0063] In step S202, acrylic resin is injected into molds 161 and 162 to mold light entrance portion 110. FIGS. 18B and 18C respectively show the overall configuration and the structure on the -Z side of the molded light entrance portion 110. As described above, light entrance portion 110 is integrally molded such that multiple light-collecting elements 111 are arranged in parallel in the Y-axis direction, and spaces 130s are included between adjacent light-collecting elements 111. A continuous portion 131 is formed on the -Z surface of each light-collecting element 111. In other words, in this example, continuous portion 131 is integrally molded with light entrance portion 110. The detailed configuration of continuous portion 131 is as described above.

[0064] In step S203, the mold 162 is opened from the mold 161. In this state, the light entrance portion 110 is housed in the mold 161.

[0065] In step S204, the molds 161, 163 and the multiple core dies 165 are set. Figures 18D and 18E show the internal state of the molds 161, 163 in a front view (viewed in the X-axis direction) and a perspective view, respectively. The mold 163 is configured similarly to the previously described mold 152. The multiple core dies 165 are configured similarly to the previously described core 153, except that their length is equal to the width of the light entrance portion 110 in the X-axis direction.

[0066] The mold 161 containing the light entrance portion 110 is turned upside down, and cores 165 are inserted into each of the plurality of spaces 130s of the light entrance portion 110. The mold 163 is then placed over the mold 161 with its internal space facing in the -Z direction. As a result, the light entrance portion 110 with the plurality of cores 165 fitted into the spaces 130s is contained in the internal space of the mold 161, and an internal space 163s is formed between the mold 161 and the mold 163.

[0067] In step S205, acrylic resin is injected into molds 161 and 163 to form light guide 100 by insert molding. The resin is injected into internal space 163s through a through-hole (not shown) in mold 163 and fills the +Z side of light entrance portion 110. When the resin cools after a certain period of time has passed, it forms light guide portion 120 and is integrated with light entrance portion 110 via continuous portion 131 (see FIG. 18C ).

[0068] In step S206, the light guide 100 is removed from the molds 161 and 163, and the plurality of core dies 165 are also pulled out from the light guide 100. Note that the plurality of core dies 165 may be formed in a tapered shape such that the +X end is narrower than the −X end, so that the core dies 165 can be easily pulled out from the light guide 100. In this way, the light guide 100 shown in FIG. 1A is obtained.

[0069] In step S207, the molds 161, 162, and 163 and the plurality of inserts 165 are cleaned, and the flow then ends. By repeating steps S201 to S207, a plurality of light guides 100 can be manufactured.

[0070] 19 shows a third manufacturing method flow S300 for the light guide 100. In this embodiment, as an example, acrylic resin is used as the molding material for the light guide 100. In other words, the light entrance section 110 and the light guide section 120 are formed from the same material.

[0071] In step S302, the light entrance section 110 is molded. The light entrance section 110 can be molded by the above-described steps S201 to S203. Fig. 20A shows the configuration of the molded light entrance section 110. The light entrance section 110 is formed as a separate body from the light guide section 120.

[0072] In step S304, light guide section 120 is molded. Details of the molding are omitted. Fig. 20B shows the configuration of molded light guide section 120. Light guide section 120 is formed as a separate body from light entrance section 110.

[0073] In step S306, the light entrance portion 110 and the light guide portion 120 are welded together to form the light guide 100. As shown in FIG. 20C , the light entrance portion 110 is placed on the +Z end face of the light guide portion 120, with one end face where the space 130s is formed facing the -Z side. This causes the -Z face of the light entrance portion 110 to abut against the +Z end face of the light guide portion 120. In this state, ultrasonic vibrations are applied to the light entrance portion 110 and / or the light guide portion 120 to weld them together. This causes the light entrance portion 110 and the light guide portion 120 to be joined together via the continuous portion 131, forming the light guide 100.

[0074] Before applying ultrasonic vibrations to the light entrance section 110 and / or the light guide section 120, the welding portion may be preheated by, for example, irradiating them with infrared light, and then the light entrance section 110 and the light guide section 120 may be brought into contact with each other, and then vibration may be applied in a direction parallel to the contacting surfaces while applying pressure in the contacting direction to generate frictional heat, thereby welding the light entrance section 110 and the light guide section 120. This allows welding without air entrapment and with reduced beads.

[0075] The light incident portion 110 and the light guiding portion 120 may be bonded together using, for example, a solvent, instead of welding. For example, the light incident portion 110 and the light guiding portion 120 may be bonded together by providing a small gap between them, pouring a photocurable adhesive into the gap using capillary force, and curing the photocurable adhesive by irradiating it with light. Alternatively, the light incident portion 110 and the light guiding portion 120 may be bonded together using optical tape (e.g., ACO04N by 3M). Alternatively, the light guide 100 may be molded using a 3D printer.

[0076] 21 shows a light guide assembly 100a according to this embodiment. The light guide assembly 100a includes two light guides 100 stacked in the Z-axis direction. Here, the upper light guide 100 is disposed on the light incident surface 110a of the lower light guide 100. A small gap is provided between the light incident surface 110a of the lower light guide 100 and the −Z surface of the upper light guide 100.

[0077] In each of the two light guides 100, the light entrance section 110 is formed with 180-degree rotational symmetry about the Z-axis direction. In the upper light guide 100, the reflecting surface 112 is located at the +Y end face, and the reflecting surface 113 is located at the -Y end face. The light guide section 120 is also formed with 180-degree rotational symmetry about the Z-axis direction. Here, the distance L from the +Y end of the light guide section 120 to the reflecting surface 112 of the light entrance section 110 closest to the +Y end is １１２ and the distance L from the −Y end of the light guide unit 120 to the light entrance unit 110 closest to the −Y end. １１３ The difference between these is approximately equal to the width of the continuous portion 131 and the discontinuous portion 132 in the Y-axis direction, that is, half the arrangement pitch P of the plurality of light-collecting elements 111 .

[0078] Therefore, in the light guide assembly 100a, the lower light guide 100 is rotated 180 degrees about the Z axis relative to the upper light guide 100. As a result, the reflecting surface 113 is located at the +Y end surface of the light incident portion 110, and the reflecting surface 112 is located at the -Y end surface. Then, the upper light guide 100 is placed on the light incident surface 110a of the lower light guide 100, and their ±Y end surfaces are aligned. As a result, the light collecting elements 111 of the upper light guide 100 are arranged offset by P / 2 in the Y-axis direction relative to the light collecting elements 111 of the lower light guide 100, and the reflecting surfaces 112 and 113 of the light collecting elements 111 of the lower light guide 100 are located below (in the -Z direction) the light transmitting portions 114 of the light collecting elements 111 of the upper light guide 100.

[0079] 22 shows the principle of light collection by the light entrance section 110 of light input to the light guide assembly 100a and light guiding by the light guide section 120. Here, the optical path of light that is not reflected by the reflective surfaces 112, 113 of the light entrance section 110 of the upper light guide 100 but enters the light guide section 120 via the light-transmitting section 114 therebetween (light-transmitting section 114 of the light collecting element 111 on the left side of the drawing) is shown. Note that the guiding of light that enters the reflective surfaces 112, 113 of the light entrance section 110 is as described above with reference to FIG. 2.

[0080] Light that enters light guide 120 via light-transmitting portion 114 of light entrance portion 110 passes through −Z end face 120b of light guide 120, leaks out of upper light guide 100, and enters lower light guide 100 from light entrance surface 110a in the −Z direction. Here, because reflecting surfaces 112 and 113 of lower light guide 100 are located below light-transmitting portion 114 of upper light guide 100, light that has passed through the +Y side of upper light-transmitting portion 114 is reflected by reflecting surface 113 on the +Y side of the lower, maintains parallel light, passes through continuation portion 131, and enters lower light guide 120. As previously explained using Figure 2, the reflected light that enters the light-guiding section 120 is reflected at the -Z end surface 120b of the light-guiding section 120 and the interface between the light-guiding section 120 and the discontinuous section 132, is guided to the right within the light-guiding section 120, and is output from the light-emitting surface 120a.

[0081] Light (not shown) that has passed through the -Y side of the upper light-transmitting portion 114 is reflected by the lower reflecting surface 112 on the -Y side, and passes through the adjacent continuous portion 131 while maintaining parallel light, before entering the lower light-guiding portion 120. The reflected light that has entered the light-guiding portion 120 is guided leftward within the light-guiding portion 120 and is output from the other light-emitting surface 120a.

[0082] In this way, by collecting light emitted from the light entrance section 110 (light-collecting element 111) of the upper light guide 100 through the transparent section 114 and light guide section 120 between them without being reflected by the reflective surfaces 112 and 113, i.e., leaked light, using the lower light guide 100, most of the light that enters the light guide assembly 100a can be trapped within the light guide section 120 and output from the light exit surface 120a.

[0083] 23 shows the configuration and light-collecting principle of a modified light guide assembly 100b. The light guide assembly 100b includes three light guides 100 stacked in the Z-axis direction. The middle light guide 100 is disposed on the light incident surface 110a of the lower light guide 100, and the upper light guide 100 is disposed on the light incident surface 110a of the middle light guide 100. Small gaps are provided between the three light guides 100. In each light guide 100, the continuous portion 131 has twice the width of the discontinuous portion 132, and the three light guides 100 are arranged with their respective light-collecting elements 111 offset by P / 3 in the Y-axis direction. As a result, the reflecting surfaces 112 and 113 of the light collecting elements 111 of the middle and lower light guides 100 are located below (in the −Z direction) the light transmitting portions 114 of the light collecting elements 111 of the upper light guide 100 .

[0084] Of the light entering light entrance surface 110a of upper light guide 100, light beams I11 and I12 are reflected by reflective surfaces 112 and 113 of upper light entrance section 110, respectively, and guided through upper light guide section 120, and output from light exit surface 120a. Of the light passing through light-transmitting section 114 between reflective surfaces 112 and 113 of upper light guide 100, light beams I21 and I22 passing through the -Y side are reflected by reflective surfaces 112 and 113 of middle light entrance section 110, respectively, and guided through middle light guide section 120, and light beams I31 and I32 passing through the +Y side are reflected by reflective surfaces 112 and 113 of lower light entrance section 110, respectively, and guided through lower light guide section 120, and output from light exit surface 120a of each light guide 100. In this way, the widths of the reflective surfaces 112, 113 and the continuous portion 131 of the light entrance portion 110 may be changed (1 to N-1), the light guide 100 may be stacked in multiple (N) stages, and the light guide assembly may be configured by offsetting the stages by P / N in the Y-axis direction.

[0085] The light guide 100 according to this embodiment is a light guide that guides light input from a light incident surface 110a to a light exit surface 120a and outputs it from the light exit surface 120a. The light guide 100 has a light incident surface 110a where light is input in the -Z direction, and reflective surfaces 112 and 113 and a light-transmitting portion 114 that are positioned in the -Z direction relative to the light incident surface 110a. The reflective surfaces 112 and 113 reflect a portion of the light input from the light incident surface 110a, and the light-transmitting portion 114 reflects another portion of the light input from the light incident surface 110a. The optical element includes a light-entering section 110 that transmits reflected light reflected by 112 and 113, a light-guiding section 120 that has a light-exiting surface 120a located on the -Z side of the light-entering section 110 and that guides the reflected light in the Y-axis direction and outputs it from the light-exiting surface 120a, continuous sections 131 that are respectively arranged at the boundaries between the light-entering section 110 and the light-guiding section 120 and are provided so that the light-transmitting section 114 and the light-guiding section 120 are continuous, and discontinuous sections 132 that are provided so that the reflective surfaces 112 and 113 are spaced apart from the light-guiding section 120. According to this, a portion of the light input to the light entrance section 110 in the -Z direction via the light entrance surface 110a is reflected by the reflecting surfaces 112 and 113 of the light entrance section 110, and the reflected light is passed from the light-transmitting section 114 of the light entrance section 110 through the continuous section 131 into the light guide section 120, and is then guided within the light guide section 120 along the Y axis, so that much of the light focused by the light entrance section 110 can be output from the light exit surface 120a.

[0086] The light guide assembly 100a according to this embodiment includes two light guides 100 stacked in the Z-axis direction. Light emitted from the light entrance portion 110 (light-collecting element 111) of the upper light guide 100 through the light-transmitting portion 114 and the light guide portion 120 between them without being reflected by the reflective surfaces 112 and 113, i.e., leaked light, is collected by the lower light guide 100, so that most of the light entering the light guide assembly 100a is trapped within the light guide portion 120 and can be output from the light exit surface 120a.

[0087] In addition, a bottom structure 121 may be provided on the bottom surface of the light-guiding section 120 so that the light guided from the light-entering section 110 to the light-guiding section 120 can be guided a long distance in the Y-axis direction without leakage or with little leakage through the light-entering section 110.

[0088] 24A shows the configuration of a light guide 100d6 according to a sixth modified example, which has a bottom surface structure 121. The light guide 100d6 includes a light entrance section 110 and a light guide section 120, with a plurality of spaces 130s arranged in the Y-axis direction between the light entrance section 110 and the light guide section 120. The plurality of spaces 130s includes, as an example, two spaces 130s0 having an equilateral triangular cross section at the center in the Y-axis direction, five spaces 130s1 having triangular cross sections extending in the -Y and -Z directions on the +Y side, and five spaces 130s2 having triangular cross sections extending in the +Y and -Z directions on the -Y side. The light guide section 120 includes, on its bottom surface, a bottom surface structure 121 that protrudes in the -Z direction and extends in the X-axis direction. Bottom surface structure 121 includes three bottom surface structures 121a having inclined surfaces facing the +Y and -Z directions on the +Y side of light guiding section 120, and three bottom surface structures 121b having inclined surfaces facing the -Y and -Z directions on the -Y side of light guiding section 120. Note that the number of spaces 130s and the number of bottom surface structures 121 may be determined arbitrarily.

[0089] 24B to 24E show the guiding of light input to light guide 100d6 according to the sixth modification. As shown in FIG. 24B , of the light entering light input section 110 from light input surface 110a, light S1 reflected by the left slopes (reflecting surfaces 112) of three spaces 130s1 on the +Y side is guided to three bottom structures 121a and reflected by the slopes, then guided to the bottoms of two spaces 130s0 and the bottom surface (discontinuous portion 132) of space 130s2 on the +Y side and reflected there, and then output from light output surface 120a on the −Y side. 24C, light S2 reflected by the left slopes (reflecting surfaces 112) of two spaces 130s1 on the -Y side is guided to the center of the bottom surface of light-guiding section 120 and reflected therein, then guided to the bottom surfaces (discontinuous portions 132) of two spaces 130s2 on the +Y side and reflected therein, then guided to the bottom surface on the -Y side of light-guiding section 120 and reflected therein, and then output from light-exiting surface 120a on the -Y side. As shown in FIG. 24D, light S3 reflected by the left slopes (reflecting surfaces 112) of two spaces 130s0 and the left slope (reflecting surface 112) of space 130s2 on the +Y side is guided to three bottom surface structures 121b and reflected therein, then guided to the bottom surfaces (discontinuous portions 132) of three spaces 130s2 on the -Y side and reflected therein, and then output from light-exiting surface 120a on the -Y side. 24E , light S4 reflected by the left slopes (reflecting surfaces 112) of the three spaces 130s2 on the -Y side is guided to the bottom surface on the -Y side of light guiding unit 120, where it is reflected, and then output from light output surface 120a on the -Y side. In this way, by providing bottom surface structure 121 in light guiding unit 120 and directing the light that entered light guiding unit 120 from light input unit 110 in the Y-axis direction within light guiding unit 120 at a small angle relative to the Y-axis direction, it is possible to guide the light to light output surface 120a with fewer reflections. In other words, the light guided distance within light guiding unit 120 can be increased.

[0090] 25A and 25B show other examples of bottom surface structures 122 and 123. Bottom surface structure 122 shown in Fig. 25A is a groove-like structure formed on the bottom surface of light-guiding section 120 so as to be recessed in the +Z direction and extend in the X-axis direction. Bottom surface structure 123 shown in Fig. 25B is an uneven structure formed on the bottom surface of light-guiding section 120 so that half of it protrudes in the -Z direction and the other half is recessed in the +Z direction and extends in the X-axis direction. The inclined surfaces of bottom surface structures 122 and 123 are inclined at the same angle as the inclined surface of bottom surface structure 121.

[0091] The −Z end faces may be mirror-finished to increase the reflectance on the inclined surfaces of the bottom structures 121 to 123. Also, a reflective film may be provided using metal or the like.

[0092] FIG. 26 shows a light guide assembly 100c formed using a light guide portion 100d6 according to a sixth modification. The light guide assembly 100c includes two light guides 100d6 stacked in the Z-axis direction. Here, the two light guides 100d6 have bottom structures 122. The upper light guide 100d6 is disposed on the light incident surface 110a of the lower light guide 100d6. The focusing elements 111 of the upper light guide 100d6 are offset by P / 2 in the Y-axis direction relative to the focusing elements 111 of the lower light guide 100d6. The reflecting surfaces 112 and 113 of the multiple focusing elements 111 of the lower light guide 100 are located below (in the −Z direction) the light-transmitting portions 114 of the multiple focusing elements 111 of the upper light guide 100. As a result, light Sa reflected by the reflective surfaces 112 and 113 of the upper light guide 100d6 is guided to the upper light guide 120 and guided in the Y-axis direction, and light Sb entering the light guide 120 via the light-transmitting portion 114 of the upper light guide 100d6 leaks out of the upper light guide 100 through the −Z end face 120b of the light guide 120, enters the lower light guide 100d6 from its light entrance surface 110a in the −Z direction, is reflected by the reflective surfaces 112 and 113 of the lower light guide 100d6, and is guided to the lower light guide 120 and guided in the Y-axis direction. As a result, most of the light that has entered the light guide assembly 100c can be confined within the two light guides 120 and output from the two light exit surfaces 120a.

[0093] The upper surface (light entrance surface 110a of light entrance section 110) and the lower surface (-Z surface of light entrance section 120) of light guide 100 according to this embodiment may be smooth, which can prevent the accumulation of dust and other particles when light guide 100 is installed outdoors.

[0094] In the light guide 100 according to the present embodiment, the light guide section 120 is formed in a plate shape extending in the Y-axis direction perpendicular to the light input direction (Z-axis direction). However, the present invention is not limited to this. The light guide section 120 may be curved in any direction intersecting the light input direction, such as an arc-shaped or spherical-shell-shaped curve. The light guide section 120 may be curved or bent in any direction from the portion overlapping with the light entrance section 110, or may be formed to extend to the light exit surface 120a by widening or narrowing, or increasing or decreasing its thickness. Thus, light collected by the light entrance section 110 is guided into the light guide section 120 and then reflected by its end surface and guided in any direction toward the light exit surface 120a.

[0095] The light output from the light output surface 120a of the light guide 100 may be input to another light guide (such as an optical fiber) different from the light guide 100 and output (emitted) at the other end of the other light guide. For example, when a second light guide 100 separate from the light guide 100 is abutted against the light guide 100 so that light output from the light guide 100 is input to the second light guide 100 without escaping into the air, the abutment surface of the light guide 100 abutting the second light guide 100 may be regarded as the light output surface 120a. Also, even when the abutment surface between the two light guides 100 is eliminated by joining the second light guide 100 separate from the light guide 100 to the light guide 100 by welding or the like, the boundary between the two light guides 100 (i.e., the abutment surface before welding) may be regarded as the light output surface 120a. Furthermore, in the second light guide 100, the surface from which light input from the light guide 100 is output may be regarded as the light output surface 120a.

[0096] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0097] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order.

[0098] 98... Plane (north-south plane), 99... Plane (movement locus plane), 100... Light guide, 100a, 100b, 100c... Light guide assembly, 100d1 to 100d6... Light guide, 110... Light entrance part, 110a... Light entrance surface, 110b... Surface treatment layer, 111... Light condensing element, 1 DESCRIPTION OF SYMBOLS 12,113...Reflection surface, 114...Transparent part, 120,120d1...Light guiding part, 120a...Light exit surface, 120b...-Z end surface, 121,121a, 121b, 122,122,123...Bottom structure, 130...Boundary part, 130s, 130s0, 130s1, 130s2 , 130sa, 130sb... hollow space (space), 131... continuous portion, 131a... first width continuous portion, 131b... second width continuous portion, 132... discontinuous portion, 132a, 132b... discontinuous portion, 132c... left discontinuous portion, 132f... left discontinuous portion, 150s... internal space, 151, 152... mold, 153... insert, 161, 162, 163... mold, 161s, 163s... internal space, 162a... protruding edge, 165... insert, Bb... lower rear slope angle, Bf... lower front slope angle, S, S1, S2, S3, S4, SA, Sa, Sb, Sc, Sf... light.

Claims

1. A light guide that guides light input from a light incident surface to a light output surface that is different from the light incident surface and outputs the light, a light entrance portion having the light entrance surface provided so that the light is input from a first direction; a light guide portion disposed closer to the light exit surface than the light entrance portion and configured to guide the light in a second direction intersecting the first direction; a continuous portion disposed at the boundary between the light entrance portion and the light guide portion, the continuous portion being provided so that the light entrance portion and the light guide portion are continuous, and a discontinuous portion being provided so that the light entrance portion and the light guide portion are spaced apart, the light incident portion has a reflecting surface provided to reflect a part of the light incident from the light incident surface, and a light transmitting portion that transmits another part of the light incident from the light incident surface and reflected light reflected by the reflecting surface, the light guiding portion is configured to further guide the reflected light in the second direction, the continuous portion is provided so that the light-transmitting portion of the light entrance portion and the light-guiding portion are continuous with each other, The discontinuous portion is provided so that the reflecting surface of the light entrance portion and the light guide portion are spaced apart.

2. The light guide according to claim 1 , wherein an end of the discontinuous portion on the light guide portion side is provided so as to extend at an angle with respect to the second direction.

3. The light guide according to claim 1 , wherein the reflective surface includes a first reflective surface and a second reflective surface that are located on one side and the other side of the light-transmitting portion in the second direction and face each other.

4. the discontinuous portion includes a first discontinuous portion where the first reflecting surface and the light guiding portion are spaced apart and a second discontinuous portion where the second reflecting surface and the light guiding portion are spaced apart, a first end portion of the first discontinuous portion on the light guiding portion side and a second end portion of the second discontinuous portion on the light guiding portion side are provided to extend inclined directions different from each other with respect to the second direction, The light guide of claim 3 .

5. The light guide according to claim 1 , wherein the reflective surfaces include a third reflective surface and a fourth reflective surface located on one side and the other side of the discontinuous portion in the second direction, respectively, and facing away from each other.

6. The light guide according to claim 5 , wherein the third reflecting surface and the fourth reflecting surface are inclined in different directions with respect to the second direction.

7. The light guide according to claim 1 , wherein the continuous portion and the discontinuous portion adjacent to the continuous portion have different widths in the second direction.

8. The light guide according to claim 1 , wherein the continuous portion and the discontinuous portion adjacent to the continuous portion have widths that are approximately equal to each other in the second direction.

9. The light guide of claim 1, wherein the interface between the discontinuous portion and the light guide portion at the boundary forms another reflective surface, reflecting the reflected light input from the transparent portion to the light guide portion through the continuous portion and guiding it to the light output surface.

10. a plurality of the reflective surfaces and the light-transmitting portions are arranged in the light entrance portion along the second direction, The light guide according to claim 1 , wherein a plurality of the continuous portions and discontinuous portions are arranged along the second direction at the boundary between the light entrance portion and the light guide portion.

11. The light guide according to claim 10 , wherein the plurality of discontinuous portions have substantially equal widths in the second direction.

12. the plurality of continuous portions include a first width continuous portion having a width of a first length in the second direction, and a second width continuous portion having a width of a second length in the second direction that is different from the first length, The first width continuous portion and the second width continuous portion are alternately arranged. The light guide of claim 10.

13. The light guide of claim 1, wherein the light entrance portion is formed to extend in the second direction, and the light entrance surface is formed in a planar shape having a width in a third direction that intersects with each of the first direction and the second direction.

14. The light guide according to claim 13 , wherein the light guide portion is formed to extend in the second direction.

15. The light guide according to claim 13 , wherein an end of the light guide portion opposite to the light entrance portion in the first direction is formed to be flat.

16. The light guide according to claim 13 , wherein the continuous portion is formed so as to extend in the third direction.

17. The light guide according to claim 16 , wherein the continuous portion is arranged so that the third direction is substantially parallel to a plane including a path of movement of the sun.

18. The light guide according to claim 16 , wherein the light guide portion is arranged so that the second direction is substantially perpendicular to a plane including a path of movement of the sun.

19. the light entrance surface includes a diffractive optical element disposed thereon or a surface treatment layer formed so that the refractive index changes continuously in the first direction; The intersection line between the plane including the sun's movement locus and the light incident surface is inclined with respect to the horizontal direction.

17. The light guide of claim 16.

20. The light guide according to claim 1 , wherein the light entrance portion and the light guide portion are formed as separate bodies and joined to each other via the continuous portion.

21. The light guide of claim 20 , wherein the light entrance portion and the light guide portion are joined by welding.

22. The light guide according to claim 1 , wherein the light entrance portion and the light guide portion are formed from the same material.

23. A light guide assembly comprising two light guides according to any one of claims 1 to 22 stacked in the first direction.

24. 24. The light guide assembly of claim 23, wherein the reflective surface of the lower light guide is located below the transparent portion of the upper light guide of the two light guides.