Light guide

Abstract

A light guide 1 guides light input from a light entry surface 10a to a light exit surface 20a different from the light entry surface, and outputs the light from the light exit surface. The light guide 1 comprises: a light entry portion 10 that has a light entry surface through which light enters in the Z-axis direction; a light guide portion 20 that is disposed on the light exit surface side to guide the light in the Y-axis direction and to output the light from the light exit surface; and a continuous portion 31 and a discontinuous portion 32 which are disposed at the boundary of the light entry portion and the light guide portion, the continuous portion 31 making the light entry portion and the light guide portion continuous, and the discontinuous portion 32 spacing the light entry portion and the light guide portion apart from each other. In this way, the light that is input into the light entry portion in the Z-axis direction through the light entry surface enters the light guide portion through the continuous portion, which is disposed at the boundary of the light entry portion and the light guide portion to make the same continuous, and the light is then guided inside the light guide portion in the Y-axis direction. Thus, the light collected by the light entry portion can be output from the light exit surface with almost no leakage.

Description

Light guide

[0001] The present invention relates to a light guide.

[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 may be configured to guide light input from a light input surface to a light output surface different from the light input surface and output the light from the light output surface. The light guide may include a light input section having the light input surface arranged so that the light is input from a first direction. The light guide may include a light guiding section arranged closer to the light output surface than the light input section and guiding the light in a second direction intersecting the first direction and outputting the light from the light output surface. The light guide may include a continuous section arranged at the boundary between the light input section and the light guiding section, such that the light input section and the light guiding section are continuous, and a discontinuous section arranged so that the light input section and the light guiding section are spaced apart. (Item 2) A plurality of the continuous sections and a plurality of the discontinuous sections may be provided at the boundary between the light input section and the light guiding section, and a plurality of the continuous sections and a plurality of the discontinuous sections may be arranged alternately along the second direction. (Item 3) The continuous portion and the discontinuous portion may be arranged such that the length of the continuous portion is shorter than the length of the discontinuous portion in the second direction. (Item 4) The light incident portion may have a reflective surface provided to reflect the light incident from the light incident surface toward the continuous portion. (Item 5) The reflective surface may be formed to reflect the light incident from a direction perpendicular to the light incident surface toward the continuous portion. (Item 6) The reflective surface may be formed to be curved or bent on a cross section including the first direction and the second direction. (Item 7) The light incident portion may further include another reflective surface arranged opposite the reflective surface and reflecting the light incident from the light incident surface toward the continuous portion. (Item 8) The light incident portion may extend in the second direction. The light incident surface may be formed in a planar shape having a width in a third direction intersecting each of the first direction and the second direction. (Item 9) The light guiding portion may be formed to extend in the second direction. (Item 10) The light guiding section may have a flat end on the opposite side from the light incident section in the first direction. (Item 11) The continuous section may be formed to extend in the third direction. (Item 12) The continuous section may be arranged so that the third direction is approximately parallel to a plane including the sun's movement locus.(Item 13) The light entrance portion and the light guide portion may be formed as separate bodies and joined to each other via the continuous portion. (Item 14) The light entrance portion and the light guide portion may be joined by welding. (Item 15) The light entrance portion and the light guide portion may be formed from the same material. (Item 16) The discontinuous portion may include a first discontinuous portion in which the separation distance between the light entrance portion and the light guide portion is constant along the second direction, and a second discontinuous portion in which the separation distance between the light entrance portion and the light guide portion is variable along the second direction. (Item 17) The light entrance portion may have a reflective surface configured to reflect the light input from the light entrance surface toward the continuous portion. The surface of the reflective surface opposite the light guide portion may be configured to form the end of the second discontinuous portion on the light entrance portion side. (Item 18) The light guide may further include a light collecting section disposed on the opposite side of the light guide section from the light input section in the first direction, so that the light that has passed through the light guide section is input thereto. (Item 19) The light guide may further include another continuous section disposed at another boundary between the light guide section and the light collecting section, so that the light guide section and the light collecting section are continuous, and another discontinuous section disposed so that the light guide section and the light collecting section are spaced apart. (Item 20) The light collecting section may include a light returning section that returns leaked light leaking from the light guide section back to the light guide section. (Item 21) The light returning section may have a reflective surface that reflects the leaked light toward the other continuous section. (Item 22) The light returning section may have a refracting surface that refracts the leaked light reflected by the reflective surface toward the other continuous section. (Item 23) The reflective surface of the light returning portion may be disposed offset in the second direction with respect to the reflective surface of the light entering portion. (Item 24) The other continuous portion may be shorter than the other discontinuous portion in the second direction, and may be disposed such that a center of the other continuous portion is offset in the second direction with respect to the reflective surface of the light returning portion and the reflective surface of the light entering portion. (Item 25) The continuous portion and the other discontinuous portion may be disposed so as to at least partially overlap with each other when viewed in the first direction.(Item 26) The other discontinuous portion may be provided such that a distance between the light guiding portion and the light collecting portion is constant along the second direction. (Item 27) The light incident portion may have a reflective surface provided to reflect the light input from the light incident surface, and the reflective surface may be formed linearly on a cross section including the first direction and the second direction. (Item 28) The discontinuous portion may be provided such that an end portion of the discontinuous portion facing the light guiding portion extends at an angle with respect to the second direction.

[0004] 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.

[0005] 5B shows the configuration of a light guide according to a first embodiment; FIG. 5C shows the configuration of a light entrance portion and a boundary portion; FIG. 5D shows the principle of light collection by the reflecting surface of a light collecting element; FIG. 5E shows collection of light input to the light guide by the light entrance portion, light guide by the light guide portion, and light leakage from the light entrance portion; FIG. 5F shows the arrangement of a light guide and the angle of incidence of light; FIG. 5G shows the light extraction efficiency for the angle of incidence shown in FIG. 3A; FIG. 5G shows a first manufacturing method flow for a light guide; FIG. 5C shows the state inside the mold after the mold and insert setting step in the first manufacturing method, as viewed from the front (cross section along reference line AA in FIG. 5B); FIG. 5D shows the state inside the mold after the mold and insert setting step in the first manufacturing method, as viewed from the side (cross section along reference line BB in FIG. 5A); FIG. 5C shows the flow of resin in the molding step in the first manufacturing method; FIG. 5D shows the state of insert removal in the insert removal step in the first manufacturing method; FIG. 5E shows a second manufacturing method flow for a light guide; FIG. 5F shows the state inside the mold after the first mold setting step in the second manufacturing method, as viewed from the front. 1 shows the configuration of a light entrance portion molded by a light entrance portion molding step using a first mold in a second manufacturing method. The configuration of the bottom surface and continuous portion of the light entrance portion is shown. The state of the second mold and the interior of the mold after the nesting setting step in a front view in the second manufacturing method. The state of the second mold and the interior of the mold after the nesting setting step in the second manufacturing method is shown in a perspective view. The third manufacturing flow of a light guide is shown. The configuration of a light entrance portion molded by a light entrance portion molding step in a third manufacturing method. The configuration of a light guide portion molded by a light guide portion molding step in a third manufacturing method. The state of the light entrance portion and the light guide portion welded by the welding step in the third manufacturing method is shown. The state of the boundary (continuous portion and discontinuous portion) between the light entrance portion and the light guide portion welded by the welding step in the third manufacturing method is shown. The configuration of a light guide according to a first modified example is shown. The light entrance portion is collected by the light entrance portion, the light guide is guided by the light guide portion, and light leaks from the light entrance portion when light is input to the light guide according to the first modified example. The configuration of a light guide according to a second embodiment is shown. 1 shows the configuration of the light return section and boundary section; 2 shows the principle of light return by the light return section; 3 shows the principle of light guiding by the light guiding section; 4 shows the manufacturing flow of the light guide body; 5 shows the configuration of the light entrance section molded by the light entrance section molding step in the fourth manufacturing method; 6 shows the configuration of the light guiding section molded by the light guiding section molding step in the fourth manufacturing method; 7 shows the configuration of the light return section molded by the light return section molding step in the fourth manufacturing method; 8 shows the state in which the light entrance section, light guiding section, and light return section are welded by the welding step in the fourth manufacturing method; 9 shows the configuration of the light guide body according to the second modified example.1 shows the configuration of a light guide according to a third modified example. 2 shows the configuration of a light guide according to a third embodiment. 3 shows the configuration of a light entrance portion and a boundary portion. 4 shows the collection of light input to the light guide by the light entrance portion and the light guiding by the light guiding portion. 5 shows a light guide assembly according to a third embodiment. 6 shows the principle of light input to the light guide assembly by the light entrance portion and the light guiding by the light guiding portion. 7 shows the configuration and light collection principle of a light guide assembly according to a modified example.

[0006] 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.

[0007] 1A and 1B respectively show the overall configuration of a light guide 1 according to a first embodiment, and the configuration of a light entrance section 10 and a boundary section 30 between the light entrance section 10 and a light guide section 20. The light guide 1 is an optical device that efficiently collects light input from a light entrance surface 10a and outputs the collected light by guiding it to a light exit surface 20a different from the light entrance surface 10a without or with little leakage, and includes the light entrance section 10, the light guide section 20, and the boundary section 30. Note that the light guide 1 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.

[0008] The light entrance unit 10 is an optical element that focuses light entering in the input direction (the -Z direction in this embodiment) through the light entrance surface 10a, and includes multiple focusing elements 11. The multiple focusing elements 11 are columnar members extending in the X-axis direction, each with 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 multiple focusing elements 11 are integrally molded and connected to each other (however, for the sake of convenience in explaining the configuration and function of the light entrance unit 10, the light entrance unit 10 will be described as including multiple focusing elements 11). As a result, the light entrance unit 10 extends in the Y-axis direction, and the +Z faces of the multiple focusing elements 11 are connected to each other to form a planar light entrance surface 10a having a width in the X-axis direction. In this manner, the light entrance surface 10a is configured so that light is input from the +Z side. Furthermore, two adjacent light-collecting elements 11 form between them a hollow space (simply referred to as space) 30s that has a substantially isosceles triangular cross section and extends in the X-axis direction.

[0009] The plurality of light-collecting elements 11 may be arranged in parallel and spaced apart from each other in the Y-axis direction. In this case, the +Z surfaces of the plurality of light-collecting elements 11 each function as an independent light-entering surface.

[0010] The light-collecting element 11 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 (e.g., a refractive index of 1.51 to 1.53 for BK7). As a result, the boundary between the light-collecting element 11 and the space 30s, i.e., the ±Y side surfaces of the light-collecting element 11, function as reflective surfaces 12 and 13 that reflect light input into the light-collecting element 11 via the light-entering surface 10a. Light entering the ±Y side surfaces from the interior of the light-collecting element 11 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 11 are formed so that their normals 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).

[0011] The reflecting surfaces 12 and 13 are disposed opposite to each other and are provided to reflect and collect light input from the light incident surface 10a toward the continuous portion 31. Here, in order to increase the reflectivity, the reflecting surfaces 12 and 13, i.e., the ±Y side surfaces of the light collecting element 11, may be mirror-finished. Also, a reflective film may be provided using a metal or the like.

[0012] The light guide 20 is an optical element disposed on the light exit surface 20a side, i.e., the -Z side, of the light entrance surface 10a of the light entrance unit 10, and guides light in the +Y and / or -Y directions and outputs it from the light exit surface 20a. The light guide 20 is formed in a plate shape extending in the Y-axis direction. Here, the width of the light guide 20 in the X-axis direction is equal to (or may be greater than) the width of the light entrance unit 10, the length in the Y-axis direction is greater than (or may be equal to) the length of the light entrance unit 10, and the thickness in the Z-axis direction is greater than the thickness of the light entrance unit 10 (this may be determined arbitrarily). The +Y side surface and / or the -Y side surface of the light guide 20 form the light exit surface 20a that outputs light, and the +Z end and the -Z end are formed flat, thereby functioning as reflective surfaces that reflect light guided into the light guide 20 inward.

[0013] The light guiding unit 20 can be made of the same material as the light-collecting element 11. In order to increase the reflectance, the +Z end and the −Z end of the light guiding unit 20 may be mirror-finished. Also, a reflective film may be provided using a metal or the like.

[0014] In addition, on the light guide path from the light entrance surface 10a of the light entrance section 10 to the light exit surface 20a of the light guide section 20, the light entrance section 10 is arranged closer to the light entrance surface 10a than the light guide section 20, and the light guide section 20 is arranged closer to the light exit surface 20a than the light entrance section 10.

[0015] The boundary portion 30 is a portion located at the boundary between the light entrance portion 10 and the light guide portion 20 , and includes a continuous portion 31 and a discontinuous portion 32 .

[0016] The continuous portion 31 is provided so that the light entrance portion 10 and the light guide portion 20 are physically continuous and so that light reflected by the reflecting surfaces 12, 13 of the light entrance portion 10 is guided into the light guide portion 20. The continuous portion 31 is formed in a plate shape extending in the X-axis direction and has a cross section (minimum width in the Y-axis direction, i.e., opening width A) in which the +Z end expands in the Y-axis direction relative to the -Z end so that it can guide light from a wide angle range, and is disposed at the center in the Y-axis direction on the -Z surface of the light-collecting element 11. The continuous portion 31 can be formed from the same material as the light-collecting element 11.

[0017] The discontinuous portions 32 are provided so as to separate the light entrance portion 10 and the light guide portion 20, and are disposed adjacent to each of the ±Y sides of the continuous portion 31. The discontinuous portions 32 include a first discontinuous portion 32a in which the separation distance between the light entrance portion 10 and the light guide portion 20 is constant along the Y-axis direction, and a second discontinuous portion 32b in which the separation distance between the light entrance portion 10 and the light guide portion 20 is variable (not constant but varying) along the Y-axis direction. In this example, the first discontinuous portions 32a are disposed at the ±Y ends of the discontinuous portion 32, and the second discontinuous portions 32b are disposed between the two first discontinuous portions 32a. Here, the back surfaces of the reflective surfaces 12, 13 (i.e., the surfaces opposite the light guide portion 20) are disposed so as to form the end of the second discontinuous portion 32b on the light entrance portion 10 side. The second discontinuous portion 32b and the first discontinuous portion 32a separate the light-guiding portion 20 from the light-entering portion 10 (the reflective surfaces 12, 13 on the -Z surface or the ±Y side surfaces), forming a space 30s therebetween and a space 30t extending from the -Z end in the ±Y direction, respectively, so that the +Z end surface of the light-guiding portion 20 functions as a reflective surface that reflects light heading from within the light-guiding portion 20 toward the light-entering portion 10 in the -Z direction.

[0018] In this embodiment, a plurality of continuous portions 31 and a plurality of discontinuous portions 32 are provided at the boundary between the light entrance portion 10 and the light guide portion 20, and the plurality of continuous portions 31 and the plurality of discontinuous portions 32 are alternately arranged along the Y-axis direction. Here, the continuous portions 31 having an opening width A are periodically arranged at a pitch P in the Y-axis direction, and further arranged so that the length of the continuous portions 31 is smaller than the length of the discontinuous portions 32, i.e., so that the aperture ratio A / P is small. As a result, light guided within the light guide portion 20 is reflected by the +Z end face where the discontinuous portions 32 are located and returned into the light guide portion 20, and leakage into the light entrance portion 10 and out of the light guide 1 via the continuous portions 31 can be suppressed.

[0019] 1B , the reflective surfaces 12 and 13 of the light entrance portion 10 reflect the light input from the light entrance surface 10 a toward the continuous portion 31. In particular, the reflective surfaces 12 and 13 are formed so as to reflect the light input from a direction perpendicular to the light entrance surface 10 a (the Z-axis direction in this embodiment) toward the continuous portion 31.

[0020] FIG. 1C shows the principle of light collection by the reflecting surfaces 12 and 13 of the light collecting element 11. The reflecting surfaces 12 and 13 are curved or bent on the YZ cross section, and are formed so as to be significantly inclined with respect to the input direction (Z-axis direction) of light on the -Z side relative to the +Z side. The reflecting surfaces 12 and 13 may also be continuously curved from the +Z side toward the -Z side. Here, the reflecting surfaces 12 and 13 form part of a parabola 19 on the YZ cross section, which is determined by a directrix 19a parallel to the Y axis located on the -Z side of the continuous portion 31 and a focal point 19b located at the center of the continuous portion 31. As a result, light that enters in the -Z direction from the light entrance surface 10a and enters the +Z side of the reflecting surfaces 12 and 13 is reflected at a relatively large angle of incidence (the angle between the normal to the reflecting surface and the input direction), light that enters the center is reflected at a medium angle of incidence, and light that enters the -Z side is reflected at a relatively small angle of incidence, resulting in light being collected toward the center of the continuous portion 31.

[0021] Furthermore, the reflecting surfaces 12 and 13 may be bent so that multiple straight lines are continuous. Here, the reflecting surfaces 12 and 13 approximately form a portion of the parabola 19 on the YZ cross section. In this case, the length and inclination of each straight line may be determined so that parallel light reflected from a straight surface including one straight line spreads over the entire range or a wide range of the Y-axis direction of the continuous portion 31 and passes through the continuous portion 31. As a result, light entering the +Z side of the reflecting surfaces 12 and 13 is reflected at a relatively large angle of incidence (the angle between the normal to the reflecting surface and the input direction), light entering the center is reflected at a medium angle of incidence, and light entering the -Z side is reflected at a relatively small angle of incidence, and is concentrated toward the continuous portion 31.

[0022] FIG. 2 shows how light input to the light guide 1 is collected by the light entrance portion 10, guided by the light guide portion 20, and leaked light from the light entrance portion 10. As described above, because the width A of the continuous portion 31 in the Y-axis direction is small, the light is collected by the continuous portion 31, and the light that enters the light guide portion 20 via the continuous portion 31 spreads within the light guide portion 20. Light that is reflected from the +Z side of the reflecting surface 13 and enters the light guide portion 20 via the continuous portion 31 enters the ±Z end faces of the light guide portion 20 at a relatively large inclination and is reflected a relatively large number of times within the light guide portion 20 before being guided in the +Y direction. Light that is reflected from the -Z side of the reflecting surface 13 and enters the light guide portion 20 via the continuous portion 31 enters the ±Z end faces of the light guide portion 20 at a small inclination and is reflected a relatively small number of times within the light guide portion 20 before being guided in the +Y direction. Therefore, the light that enters the reflecting surface 13 is reflected by the ±Z end faces and guided in the +Y direction while spreading over a wide angle range overall. Here, there is a possibility that the light may return to the light entrance section 10 via a continuous section 31 different from the continuous section 31 through which the light entered the light guide section 20, and then leak out of the light guide body 1. However, the small aperture ratio A / P suppresses light leakage.

[0023] 3A shows the arrangement of the light guide 1 and the angle of incidence of light. The light guide 1 is arranged so that the extension direction of the continuous portion 31 (i.e., the X-axis direction) is approximately parallel to a plane (movement trajectory plane) 99 containing the sun's movement trajectory, and so that the normal direction of the light incident surface 10a is approximately parallel to the movement trajectory plane 99, i.e., so that the light collecting element 11 faces approximately parallel to the movement trajectory plane 99. The angle of incidence of light is determined based on the normal direction of the light incident surface 10a. Here, the sun's movement trajectory plane 99 is the plane formed by the trajectory of the sun's orbital motion.

[0024] 3B shows the light extraction efficiency of the light guide 1 for the incident angle shown in FIG. 3A. The extraction efficiency can be analyzed using so-called ray simulation and is calculated by dividing the amount of light output from the light output surface 20a by the amount of light input to the light input surface 10a. When the incident angle is zero (normal incidence on the light input surface 10a), most of the light entering the light input section 10 through the light input surface 10a is guided within the light guide section 20 and output from the light output surface 20a. 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 obtained at least within the incident angle range of 0 to 40 degrees, i.e., during the long hours of sunlight.

[0025] In addition, the inclination of the light guide 1 may be adjusted according to the sun's noon angle, for example, multiple times throughout the year, so that the extension direction of the continuous portion 31 and the normal direction of the light incident surface 10a are approximately parallel to the sun's movement trajectory plane 99.

[0026] 4 shows a first manufacturing method flow S100 for the light guide 1. In this embodiment, as an example, acrylic resin is used as the molding material for the light guide 1. In other words, the light entrance section 10 and the light guide section 20 are formed from the same material.

[0027] In step S101, molds 51 and 52 and multiple inserts 53 are set. Figures 5A and 5B show the interiors of molds 51 and 52 from a front view (along reference line AA in Figure 5B) and a side view (along reference line BB in Figure 5A), respectively. Mold 51 is a metal mold for forming light entrance section 10 and includes an internal space sized and shaped to accommodate light entrance section 10 and multiple inserts 53. Mold 52 is a metal mold for forming light guide section 20 and includes an internal space sized and shaped to accommodate light guide section 20. Multiple inserts 53 are metal molds for forming spaces 30s and 30t in light entrance section 10 (between multiple light-collecting elements 11), and are solid columnar bodies with a cross-sectional shape that is approximately an isosceles triangle with protruding pieces extending to the left and right from its base.

[0028] The mold 52 is placed with its internal space facing the +Z direction, multiple nesting pieces 53 are arranged on the mold 52 in the Y-axis direction so as to straddle the internal space of the mold 52 in the X-axis direction, and the mold 51 is placed over the mold 52 with its internal space facing the -Z direction. As a result, an internal space 50s is formed between the molds 51 and 52, separated vertically by the multiple nesting pieces 53 except for a portion.

[0029] In step S102, acrylic resin is injected into the molds 51 and 52 to form the light guide 1. Fig. 5C shows the flow of resin inside the molds 51 and 52. The resin is injected downward through a through-hole (not shown) in the mold 52 and fills the internal space 50s in the direction indicated by the black arrow, filling upward through the gaps between the multiple inserts 53. After a certain period of time has passed and the resin has cooled, the process moves to the next step.

[0030] In step S103, mold 51 is pulled in the +Z direction to open the mold, thereby exposing light entrance section 10 on mold 52 with light guide section 20 fitted in the internal space of mold 52, as shown in FIG.

[0031] In step S104, the plurality of core dies 53 are pulled out. Fig. 5D shows the state in which the plurality of core dies 53 are pulled out from the light guide 1. The plurality of core dies 53 are pulled out in the direction of the outline arrow (+X direction). Note that the plurality of core dies 53 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 1.

[0032] In step S105, the light guide 1 is removed from the mold 52. This gives the light guide 1 shown in FIG. 1A.

[0033] In step S106, the molds 51 and 52 and the plurality of inserts 53 are cleaned, and the flow ends thereafter. By repeating steps S101 to S106, a plurality of light guide bodies 1 can be manufactured.

[0034] 6 shows a second manufacturing method flow S200 for the light guide 1. In this embodiment, as an example, acrylic resin is used as the molding material for the light guide 1. In other words, the light entrance section 10 and the light guide section 20 are formed from the same material.

[0035] In step S201, molds 61 and 62 are set. FIG. 7A shows the interior of the molds 61 and 62 as viewed from the front (as viewed in the X-axis direction). The molds 61 and 62 are a pair of metal molds for forming the light entrance section 10. The mold 61 includes an internal space sized and shaped to accommodate the light entrance section 10. The mold 62 has multiple protruding edges 62a that protrude from the top surface in the +Z direction and are aligned in the Y-axis direction. The multiple protruding edges 62a are structures for forming spaces 30s and 30t in the light entrance section 10 (between the multiple light-collecting elements 11), and are formed to have a cross-sectional shape that includes an approximately isosceles triangle with protruding pieces extending to the left and right from its base, and extend in the X-axis direction.

[0036] The mold 62 is placed with its multiple protruding sides 62a facing in the +Z direction, and the mold 61 is placed over the mold 62 with its internal space facing in the -Z direction to accommodate the protruding sides 62a. This forms an internal space 61s between the molds 61 and 62.

[0037] In step S202, acrylic resin is injected into molds 61 and 62 to mold the light entrance portion 10. FIGS. 7B and 7C show the overall configuration and the structure on the -Z side of the molded light entrance portion 10, respectively. As described above, the light entrance portion 10 is integrally molded such that multiple light-collecting elements 11 are arranged side by side in the Y-axis direction, with spaces 30s being formed between adjacent light-collecting elements 11. A continuous portion 31 is formed at the center of the -Z face of each light-collecting element 11 in the Y-axis direction, protruding from the -Z face of the light-collecting element 11 in the -Z direction and extending in the X-axis direction. In other words, in this example, the continuous portion 31 is integrally molded with the light entrance portion 10. The detailed configuration of the continuous portion 31 is as described above.

[0038] In step S203, the mold 62 is opened from the mold 61. In this state, the light entrance portion 10 is housed in the mold 61.

[0039] In step S204, the molds 61, 63 and the multiple inserts 65 are set. Figures 7D and 7E show the interiors of the molds 61, 63 in a front view (viewed in the X-axis direction) and a perspective view, respectively. The mold 63 is configured similarly to the mold 52 described above. The multiple inserts 65 are configured similarly to the insert 53 described above, except that their length is equal to the width of the light entrance portion 10 in the X-axis direction.

[0040] The mold 61 containing the light entrance section 10 is turned upside down, and cores 65 are inserted into each of the plurality of spaces 30s of the light entrance section 10. The mold 63 is then placed over the mold 61 with its internal space facing in the -Z direction. As a result, the light entrance section 10 with the plurality of cores 65 fitted into the spaces 30s is contained in the internal space of the mold 61, and an internal space 63s is formed between the mold 61 and the mold 63.

[0041] In step S205, acrylic resin is injected into the molds 61 and 63 to form the light guide 1 by cast-in-place molding. The resin is injected into the internal space 63s through a through-hole (not shown) in the mold 63 and fills the +Z side of the light entrance portion 10. When the resin cools after a certain period of time has passed, the resin forms the light guide portion 20 and is integrated with the light entrance portion 10 via the continuous portion 31 (see FIG. 7C ).

[0042] In step S206, the light guide 1 is removed from the molds 61 and 63, and the plurality of core dies 65 are pulled out from the light guide 1. Note that the plurality of core dies 53 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 1. In this way, the light guide 1 shown in FIG. 1A is obtained.

[0043] In step S207, the molds 61, 62, and 63 and the plurality of inserts 65 are cleaned. This completes the flow. By repeating steps S201 to S207, a plurality of light guides 1 can be manufactured.

[0044] 8 shows a third manufacturing method flow S300 for the light guide 1. In this embodiment, as an example, acrylic resin is used as the molding material for the light guide 1. In other words, the light entrance section 10 and the light guide section 20 are formed from the same material.

[0045] In step S302, the light entrance section 10 is molded. The light entrance section 10 can be molded by the above-described steps S201 to S203. Fig. 9A shows the configuration of the molded light entrance section 10. The light entrance section 10 is formed as a separate body from the light guide section 20.

[0046] In step S304, the light guide section 20 is molded. Details of the molding are omitted. Fig. 9B shows the configuration of the molded light guide section 20. The light guide section 20 is formed as a separate body from the light entrance section 10.

[0047] In step S306, the light entrance portion 10 and the light guide portion 20 are welded together to form the light guide 1. As shown in FIG. 9C , the light entrance portion 10 is placed on the +Z end face of the light guide portion 20, with the end face where the space 30s is formed facing the -Z side. As a result, as shown in FIG. 9D , the continuous portion 31 integrally molded on the -Z face of the light entrance portion 10 abuts the +Z end face of the light guide portion 20. In this state, ultrasonic vibrations are applied to the light entrance portion 10 and / or the light guide portion 20 to weld them together. As a result, the light entrance portion 10 and the light guide portion 20 are joined to each other via the continuous portion 31, and the light guide 1 is formed.

[0048] The light entrance portion 10 and the light guide portion 20 may be bonded to each other by, for example, a solvent, instead of by welding. The light guide 1 may also be molded using a 3D printer.

[0049] The light guide 1 of the first embodiment is an optical device that guides light input from a light entrance surface 10a to a light exit surface 20a that is different from the light entrance surface 10a and outputs it from the light exit surface 20a, and is equipped with a light entrance section 10 having the light entrance surface 10a through which light enters in the Z-axis direction, a light guide section 20 arranged on the side of the light exit surface 20a and guiding light in the Y-axis direction and outputting it from the light exit surface 20a, a continuous section 31 that connects the light entrance section 10 and the light guide section 20, and a discontinuous section 32 that separates the light entrance section 10 and the light guide section 20, which are arranged at the boundary between the light entrance section 10 and the light guide section 20. According to this, light input into light entrance portion 10 in the Z-axis direction via light entrance surface 10a enters light entrance portion 20 via continuous portion 31, which is disposed at the boundary between light entrance portion 10 and light guide portion 20 and continues them, and is guided in the Y-axis direction within light guide portion 20, so that the light collected by light entrance portion 10 can be output from light exit surface 20a with almost no leakage. Furthermore, by structurally separating light guide 1 into two portions, light entrance portion 10 that collects light and light guide portion 20 that guides light, and connecting light entrance portion 10 to light guide portion 20 via continuous portion 31 whose width is smaller than that of discontinuous portion 32, it is possible to suppress light leakage from light guide portion 20 to light entrance portion 10 via continuous portion 31.

[0050] In addition, the light guide 1 of the first embodiment is provided with a pair of reflective surfaces 12, 13 facing the ±Y side surfaces of one focusing element 11, but this is not limited to this, and a reflective surface may be provided on only one of the ±Y side surfaces.

[0051] In addition, the light output from the light exit surface 20a of the light guide 1 may be input to another light guide (such as an optical fiber) other than the light guide 1, and output (emitted) at the other end of the other light guide.

[0052] 10 shows the configuration of a light guide 1d according to the first modification, in particular the detailed configuration of a light entrance portion 10d and a boundary portion 30d between the light entrance portion 10d and a light guide portion 20d. The light guide 1d includes a light entrance portion 10d, a light guide portion 20d, and a boundary portion 30d.

[0053] Like the previously described light entrance unit 10, the light entrance unit 10d is an optical element that focuses light entering in the input direction (the -Z direction in this example) through the light entrance surface 10a, and includes multiple focusing elements 11d. The multiple focusing elements 11d are columnar members extending in the X-axis direction, each with a substantially parallelogram-shaped cross section with a 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 their +Z ends in contact with each other and their ±Y slopes spaced apart. In this example, the multiple focusing elements 11d are integrally molded and connected to each other. As a result, the light entrance unit 10d extends in the XY directions, and the +Z faces of the multiple focusing elements 11d are connected to each other to form a planar light entrance surface 10a that extends in the XY directions. Furthermore, two adjacent focusing elements 11d form a space 30s between them, extending in the +Y and -Z directions and also in the X-axis direction.

[0054] The light-collecting elements 11d 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 11d each function as an independent light-entering surface.

[0055] As described above, the light-collecting element 11d can be formed using a resin or glass having a high refractive index. As a result, the boundary between the light-collecting element 11d and the space 30s, i.e., the -Y inclined surface of the light-collecting element 11, functions as a reflecting surface 14 that reflects light input into the light-collecting element 11d through the light-entering surface 10a. When light enters the -Y side surface from inside the light-collecting element 11d at an angle equal to or greater than the critical angle, it is totally reflected. Therefore, the -Y side surface of the light-collecting element 11d is formed so that its normal forms an angle equal to or greater than the critical angle with respect to the input direction of the light (the Z-axis direction in this example).

[0056] The reflecting surface 14 reflects the light input from the light-entering surface 10a so as to condense the light toward the continuous portion 31. Here, in order to increase the reflectivity, the reflecting surface 14, i.e., the -Y side surface of the light-condensing element 11d, may be mirror-finished. Also, a reflective film may be provided using a metal or the like.

[0057] The light guide section 20d is configured in the same manner as the light guide section 20 described above.

[0058] The boundary portion 30d is a portion located at the boundary between the light entrance portion 10d and the light guide portion 20d, and includes a continuous portion 31 and a discontinuous portion 32.

[0059] The continuous portion 31 physically connects the light entrance portion 10d and the light guide portion 20d, and guides light reflected by the reflecting surface 14 of the light entrance portion 10d into the light guide portion 20d. The continuous portion 31 is formed in a plate shape extending in the X axis direction and having a width in the Y axis direction, i.e., an opening width A, and is disposed on the +Y side of the -Z plane of the light collecting element 11. The continuous portion 31 can be formed from the same material as the light collecting element 11.

[0060] Discontinuous portion 32 is a portion provided to separate light entrance portion 10d and light guide portion 20d, and is disposed adjacent to the -Y side of continuous portion 31. Discontinuous portion 32 separates light guide portion 20d from light entrance portion 10d (-Z surface) to form space 30t therebetween that extends in the +Y direction from the -Z end of space 30s, and thereby the +Z end surface of light guide portion 20d functions as a reflective surface that reflects, in the -Z direction, light traveling from inside light guide portion 20d toward light entrance portion 10d.

[0061] In this modification, continuous portions 31 and discontinuous portions 32 are alternately arranged in the Y-axis direction at the boundary between light entrance portion 10d and light guide portion 20d. Here, continuous portions 31 having an opening width A are periodically arranged at a pitch P in the Y-axis direction, and further, continuous portions 31 are arranged so as to be shorter than discontinuous portions 32, i.e., so as to have a smaller aperture ratio A / P. This makes it possible to prevent light guided through light guide portion 20d from being reflected by the +Z end face where discontinuous portions 32 are located and returned into light guide portion 20, and from leaking via continuous portions 31 into light entrance portion 10d and out of light guide body 1d.

[0062] The reflecting surface 14 of the light entrance portion 10d reflects light input from the light entrance surface 10a toward the continuous portion 31. In particular, the reflecting surface 14 is formed so as to reflect light input from a direction perpendicular to the light entrance surface 10a (in this example, the Z-axis direction) toward the continuous portion 31. The reflecting surface 14 can be formed in the same manner as the reflecting surfaces 12 and 13 described above. As a result, light entering the +Z side of the reflecting surface 14 is reflected at a relatively large angle of incidence (the angle between the normal to the reflecting surface and the input direction), light entering the center is reflected at a medium angle of incidence, and light entering the -Z side is reflected at a relatively small angle of incidence, and the light is collected toward the continuous portion 31.

[0063] 11 shows the collection of light input to the light guide 1d by the light input portion 10d, the light guided by the light guide portion 20d, and the light leakage from the light input portion 10d. As described above, because the width A of the continuous portion 31 in the Y-axis direction is small, the light is collected by the continuous portion 31 and then enters the light guide portion 20d via the continuous portion 31, spreading within the light guide portion 20d. Light reflected from the +Z side of the reflecting surface 14 and enters the light guide portion 20d via the continuous portion 31 enters the ±Z end faces of the light guide portion 20d at a relatively large inclination, and is guided in the +Y direction while being reflected a relatively large number of times within the light guide portion 20d. Light reflected from the -Z side of the reflecting surface 14 and enters the light guide portion 20d via the continuous portion 31 enters the ±Z end faces of the light guide portion 20d at a small inclination, and is guided in the +Y direction while being reflected a relatively small number of times within the light guide portion 20d. Therefore, light that enters reflecting surface 14 is reflected by the ±Z end surfaces while spreading over a wide angle range as a whole, and is guided in the +Y direction. Here, the light may return to light entrance portion 10d via a continuation portion 31 different from the continuation portion 31 through which it entered light guide portion 20d, and may leak out of light guide body 1d. However, light leakage is suppressed by the small aperture ratio A / P.

[0064] In the light guide 1d according to the first modification, light input to the light entrance portion 10d in the Z-axis direction via the light entrance surface 10a enters the light entrance portion 20d via the continuous portion 31 that is disposed at the boundary between the light entrance portion 10d and the light guide portion 20d and continues them, and is guided within the light guide portion 20d in the Y-axis direction, so that the light collected by the light entrance portion 10d can be output from the light exit surface 20a with almost no leakage. Furthermore, by structurally separating the light guide 1d into two portions, the light entrance portion 10d that collects light and the light guide portion 20d that guides light, and connecting the light entrance portion 10d to the light guide portion 20d via the continuous portion 31 that is narrower than the discontinuous portion 32, it is possible to suppress leakage of light from the light guide portion 20d to the light entrance portion 10d via the continuous portion 31.

[0065] Furthermore, the cross-sectional shape is determined so that the -Z end face of each of the plurality of light-collecting elements 11d is located approximately on the -Z side of the reflecting surface 14 of the adjacent light-collecting element 11. As a result, the continuous portion 31 and discontinuous portion 32 for one light-collecting element 11 are located approximately on the -Z side of the reflecting surface 14 of the adjacent light-collecting element 11, and when viewed in the light input direction (the -Z direction in this example), the reflecting surfaces 14 of the plurality of light-collecting elements 11d are continuous in the Y-axis direction. Therefore, most of the light input in the -Z direction from the light incident surface 10a is reflected by the reflecting surface 14 and is guided to the light-guiding section 20 via the continuous portion 31.

[0066] The upper surface (light entrance surface 10a of the light entrance section 10, 10d) and the lower surface (-Z surface of the light entrance section 20, 20d) of the light guide 1 according to the first embodiment and the light guide 1d according to the modified example may be smooth, which can prevent the accumulation of dust and other particles when the light guide 1, 1d is installed outdoors.

[0067] In the light guide 1 according to the first embodiment and the light guide 1d according to the modified example, the light guide sections 20, 20d are formed in a plate shape extending in the Y-axis direction perpendicular to the light input direction (Z-axis direction). However, this is not limited thereto, and the light guide sections 20, 20d may be curved in any direction intersecting the light input direction, such as curved in an arc or spherical shell shape. Furthermore, the light guide sections 20, 20d may be curved or bent in any direction from the portion overlapping with the light entrance sections 10, 10d, or may be formed to extend to the light exit surface 20a by widening or narrowing, or by increasing or decreasing its thickness. Thus, light collected by the light entrance section 10 is guided into the light guide section 20 and then reflected by its end surface and guided in any direction toward the light exit surface 20a.

[0068] 12A and 12B respectively show the overall configuration of a light guide 1d2 according to a second embodiment, as well as the configuration of a light return section 40 and a boundary section 70 between the light return section 40 and the light guide section 20. The light guide 1d2 is an optical device that efficiently collects light input from a light incident surface 10a and guides the collected light with minimal leakage to a light exit surface 20a different from the light incident surface 10a for output, and includes a light incident section 10, a light guide section 20, a boundary section 30, a light return section 40, and a boundary section 70. Note that the light guide 1d2 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.

[0069] The light entrance section 10, the light guide section 20, and the boundary section 30 are configured in the same manner as the light entrance section 10, the light guide section 20, and the boundary section 30 in the light guide body 1d2 according to the first embodiment, respectively.

[0070] The light return section 40 is an example of a light collecting section arranged on the opposite side of the light guide section 20 from the light input section 10 in the Z-axis direction, and is provided so that light that has passed through the light guide section 20 is input. The light return section 40 is an optical member that returns transmitted light that has passed through the light guide section 20 (i.e., leaked light leaking from the light guide section 20 to the -Z side) to the light guide section 20, and has a plurality of light return elements 41. The plurality of light return elements 41 are columnar members that have an inverted, approximately concave cross section with a maximum width P in the Y-axis direction and a height h in the Z-axis direction and extend in the X-axis direction. They are each arranged below (on the -Z side of) the plurality of light collecting elements 11, and 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 light return elements 41 are integrally molded by being connected to each other (however, for convenience of explaining the configuration and function of the light return section 40, the light return section 40 will be described as including a plurality of light return elements 41). As a result, the light return section 40 extends in the XY directions, and the +Z faces of the multiple light return elements 41 are connected to each other to form a plane that extends in the XY directions. In addition, a hollow space (simply referred to as space) 40s having a substantially isosceles triangular cross section and extending in the X-axis direction is formed at the center of the -Z face of the light return element 41, and a hollow space (simply referred to as space) 40t having an isosceles triangular cross section and extending in the X-axis direction is formed between two adjacent light-collecting elements 11.

[0071] Like the light-collecting element 11, the light-returning element 41 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 (e.g., a refractive index of 1.51 to 1.53 for BK7). As a result, the boundary between the light-returning element 41 and the space 40s, i.e., the opposing inclined surfaces formed in the center of the light-returning element 41, function as reflective surfaces 42, 43 that reflect light input from the light-collecting element 11 located directly above (on the +Z side of) the light-returning element 41 to the region between them and the light-guiding unit 20 without being reflected by the reflective surfaces 12, 13. Light is totally reflected when it enters the reflective surfaces 42, 43 from inside the light-returning element 41 at an angle equal to or greater than the critical angle. The critical angle is approximately 42 degrees for acrylic resin, approximately 41 degrees for polycarbonate resin, and approximately 42 degrees for glass. Therefore, the inclined surface of the light returning element 41 is formed so that the normal to the inclined surface forms an angle equal to or larger than the critical angle with respect to the incident direction of the light (the Z-axis direction in this embodiment).

[0072] FIG. 13 shows the principle of light return by the light return section. The light return element 41 is disposed below the light collecting element 11. The reflecting surfaces 42 and 43 of the light return section 40 (light return element 41) are disposed offset in the Y-axis direction relative to the reflecting surfaces 12 and 13 of the light entrance section 10. In this example, the offset is P / 2. As a result, in the YZ cross section, the reflecting surface 42 reflects, toward the continuous section 71 described below, the leakage light (thick line in the figure) that is input into the light collecting element 11 in the -Z direction via the light entrance surface 10a, passes through the light guide section 20 via an area on the +Y side of the center of the light collecting element 11 and on the -Y side of the reflecting surface 12, leaks from the -Z surface of the light guide section 20, and enters the light return element 41 (light return element 41a in this example). In this example, the reflecting surface 42 reflects light toward a continuous portion 71 (the rightmost continuous portion 71 in the figure) located on the boundary between two adjacent light return elements 41b and 41c on the +Y side of the light return element 41a. The reflecting surface 43 reflects, among the light input into the light collecting element 11 in the -Z direction via the light incident surface 10a, the leakage light (not shown) that passes through the light guide unit 20 via the region on the -Y side from the center of the light collecting element 11 and the +Y side of the reflecting surface 13, and leaks from the -Z surface of the light guide unit 20 and enters the light return element 41a, toward another continuous portion 71 (located on the boundary between the two light return elements 41 adjacent on the -Y side of the light return element 41).

[0073] Furthermore, the boundary between the light return element 41 and the space 40t, i.e., the ±Y side surfaces of the light return element 41, function as refractive surfaces 44, 45 that refract the leaked light reflected by the reflecting surfaces 42, 43 toward the continuous portion 71. Here, the refractive surface 44 formed on the +Y side surface of the light return element 41a and the refractive surface 45 formed on the -Y side surface of the light return element 41b adjacent to the +Y side of the light return element 41a form parts of two circles 49 that are tangent in the Y-axis direction, i.e., opposing arcs. As a result, the opposing refractive surfaces 44, 45 and the space 40t located therebetween form a focal point 49a on the boundary between the light return element 41b and the light return element 41c adjacent to the +Y side of the light return element 41b (i.e., the center of the continuous portion 71). The leaked light reflected by the reflecting surface 42 within the light returning element 41a is emitted into the space 40t via the refractive surface 44, enters the light returning element 41b via the refractive surface 45 of the light returning element 41b, is condensed at the focal point 49a, and returns to the light guiding unit 20 via the continuation portion 71. Similarly, the leaked light reflected by the reflecting surface 43 within the light returning element 41a is condensed via the refractive surface formed on the -Y side surface of the light returning element 41a, the space, and the refractive surface formed on the +Y side surface of the light returning element adjacent to the -Y side of the light returning element 41a, and returns to the light guiding unit 20 via the continuation portion (none of which are shown).

[0074] The boundary portion 70 is a portion located at the boundary between the light guide portion 20 and the light return portion 40 , and includes a continuous portion 71 and a discontinuous portion 72 .

[0075] The continuous portion 71 is provided so that the light guide portion 20 and the light return portion 40 are physically continuous with each other, and returns leaked light reflected by the reflecting surfaces 42, 43 of the light return portion 40 (light return element 41) into the light guide portion 20. The continuous portion 71 is formed in a plate shape extending in the X-axis direction, and is disposed on the boundary between two adjacent light return elements 41. The continuous portion 71 can be formed from the same material as the light return elements 41.

[0076] Discontinuous portion 72 is a portion provided to separate light guide portion 20 and light return portion 40, and is disposed between the ±Y end portions of light return element 41 where continuous portion 71 is located. Discontinuous portion 72 separates the +Z face of light return portion 40 from light guide portion 20 to form space 70s therebetween, and thereby the −Z end face of light guide portion 20 functions as a reflective surface that reflects light traveling from inside light guide portion 20 toward light return portion 40 in the +Z direction.

[0077] In this embodiment, the continuous portions 71 and the discontinuous portions 72 are alternately arranged in the Y-axis direction at the boundary between the light guide portion 20 and the light return portion 40. Here, the continuous portions 71 and the discontinuous portions 72 are provided so that at least a portion of each of them overlaps with each other when viewed in the Z-axis direction. Furthermore, the discontinuous portions 72 are provided so that the distance between the light guide portion 20 and the light return portion 40 is constant along the Y-axis direction.

[0078] Furthermore, continuous portions 71 are periodically arranged in the Y-axis direction at pitch P, and are arranged so that continuous portions 71 are shorter than discontinuous portions 72, i.e., so that the width / pitch P of continuous portions 71 is smaller. This makes it possible to prevent light guided within light-guiding portion 20 from being reflected by the −Z end face where discontinuous portions 72 are located and returned to light-guiding portion 20, and from leaking via continuous portions 71 to light-returning portion 40 and out of light guide 1.

[0079] 14 shows the principle of light guiding by the light guide unit 20. The center of the continuous portion 71 is arranged so as to be offset in the Y-axis direction with respect to the reflecting surfaces 42, 43 of the light return unit 40 (light return element 41) and the reflecting surfaces 12, 13 of the light input unit 10 (light collecting element 11). In this embodiment, the continuous portion 71 is arranged below (on the -Z side) the boundary between two adjacent light collecting elements 11. Alternatively, the continuous portion 71 may be arranged below the reflecting surfaces 12, 13 of the light collecting elements 11. This prevents light that enters the light guide unit 20 from the light collecting elements 11 via the region between the reflecting surfaces 12, 13 without being reflected by them from the light collecting elements 11, from entering the light return unit 40 via the continuous portion 71.

[0080] Furthermore, a wide discontinuous portion 72 is formed on the +Z surface of the light returning element 41, and reflects light that has been reflected by the reflecting surfaces 12 and 13 of the light incident portion 10 and entered the light guiding portion 20 via the continuous portion 31. Here, the light reflected on the +Z side of the reflecting surface 13 passes through the continuous portion 31 at a small angle with respect to the Z axis and enters the vicinity of the -Y end of the discontinuous portion 72 on the light returning element 41 adjacent to the +Y side at an angle equal to or greater than the critical angle, the light reflected at the center of the reflecting surface 13 passes through the continuous portion 31 at a medium angle with respect to the Z axis and enters the center of the discontinuous portion 72 at an angle equal to or greater than the critical angle, and the light reflected on the -Z side of the reflecting surface 13 passes through the continuous portion 31 at a large angle with respect to the Z axis and enters the vicinity of the +Y end of the discontinuous portion 72 at an angle equal to or greater than the critical angle, and each is reflected by the reflecting surface on the discontinuous portion 72. Much of the light that enters the light-guiding section 20 through the reflective surfaces 12 and 13 of the light-entering section 10 and the continuous section 31 can be reflected by the reflective surface on the discontinuous section 72 and returned (confined) within the light-guiding section 20.

[0081] 15 shows a fourth manufacturing method flow S400 for the light guide 1d4. In this embodiment, as an example, acrylic resin is used as the molding material for the light guide 1d2. That is, the light entrance section 10, the light guide section 20, and the light return section 40 are formed from the same material.

[0082] In step S402, the light entrance section 10 is molded. The light entrance section 10 can be molded by the above-described steps S201 to S203. Fig. 16A shows the configuration of the molded light entrance section 10. The light entrance section 10 is formed as a separate body from the light guide section 20 and the light return section 40.

[0083] In step S404, the light guide section 20 is molded. Details of the molding are omitted. Fig. 16B shows the configuration of the molded light guide section 20. The light guide section 20 is formed as a separate body from the light entrance section 10 and the light return section 40.

[0084] In step S406, the light return section 40 is molded. The light return section 40 can be molded in the same manner as the light entrance section 10. That is, a mold including an internal space having a size and shape capable of accommodating the light return section 40 and having a plurality of grooves on its ceiling surface arranged in the Y-axis direction and having a cross-sectional shape complementary to the continuous section 71 is placed over a mold having a plurality of protruding sides on its top surface arranged in the Y-axis direction and having a cross-sectional shape complementary to the spaces 40s, 40t, to form an internal space between them, and acrylic resin is poured into the internal space, thereby molding the light return section 40.

[0085] 16C shows the configuration of the molded light return section 40. In the light return section 40, a plurality of light return elements 41 are connected in the Y-axis direction, a continuous portion 71 is disposed on the boundary between adjacent light return elements 41 on the +Z plane, and spaces 40s and 40t are formed on the −Z plane that are aligned in the Y-axis direction.

[0086] In step S406, the light entrance portion 10, the light guide portion 20, and the light return portion 40 are welded together to form the light guide 1d2. As shown in FIG. 16D , the light entrance portion 10 is disposed on the +Z end face of the light guide portion 20, with one end face having the space 30s facing the -Z side, and the light return portion 40 is disposed on the -Z end face of the light guide portion 20, with one end face having the spaces 40s and 40t facing the -Z side. As a result, the continuous portion 31 integrally molded on the -Z face of the light entrance portion 10 abuts the +Z end face of the light guide portion 20, and the continuous portion 71 integrally molded on the +Z face of the light return portion 40 abuts the -Z end face of the light guide portion 20. In this state, ultrasonic vibration is applied to at least one of the light entrance portion 10, the light guide portion 20, and the light return portion 40 to weld them together. As a result, the light entrance section 10 and the light guide section 20 are joined to each other via the continuous section 31, and the light guide section 20 and the light return section 40 are joined to each other via the continuous section 71, thereby forming the light guide body 1d2.

[0087] Note that the method is not limited to welding, and for example, a solvent may be used to bond the light entrance section 10, the light guide section 20, and the light return section 40. Furthermore, the light guide body 1d2 may be molded using a 3D printer.

[0088] The light guide 1d2 of the second embodiment is an optical device that guides light input from a light entrance surface 10a to a light exit surface 20a that is different from the light entrance surface 10a and outputs it from the light exit surface 20a, and is equipped with a light entrance section 10 having the light entrance surface 10a through which light enters in the Z-axis direction, a light guide section 20 that is arranged on the side of the light exit surface 20a and guides light in the Y-axis direction and outputs it from the light exit surface 20a, a continuous section 31 that connects the light entrance section 10 and the light guide section 20 and a discontinuous section 32 that separates the light entrance section 10 and the light guide section 20, which are arranged at the boundary between the light entrance section 10 and the light guide section 20, and a light return section 40 that is arranged on the opposite side of the light entrance section 10 from the light guide section 20 in the Z-axis direction and returns leaked light that leaks from the light guide section 20 to the light guide section 20. As a result, the light returning section 40 returns light that is input from the light entering section 10 (light-collecting element 11) to the light returning section 40 via the area between the reflecting surfaces 12 and 13 and the light guiding section 20 without being reflected by them, i.e., leaked light, to the light guiding section 20, thereby trapping much of the light that entered the light entering section 10 within the light guiding section 20 and outputting it from the light exit surface 20a.

[0089] 17 shows the configuration of a light guide 1d3 according to a second modification. The light guide 1d3 further comprises a bottom 48 in addition to the light guide 1d2 according to the second embodiment. The bottom 48 is formed in a plate shape extending in the Y-axis direction using the same material as the light return section 40, and is fused to the -Z face of the light return section 40. The bottom 48 and the light return section 40 may also be formed integrally. This allows leakage light that leaks toward the -Z side without being reflected by the reflective surfaces 42 and 43 to be reflected by the -Z face of the bottom 48, guided and confined within the bottom 48 in the Y-axis direction, and returned to the +Z direction.

[0090] FIG. 18 shows the configuration of a light guide 1d4 according to a third modification. The light guide 1d4 includes a light return section 40d, which is formed by forming only a space 40s on the −Z plane relative to the light return section 40 of the light guide 1d2 according to the second embodiment. Here, a reflective film made of metal or the like may be provided on the reflective surfaces 42, 43 to ensure total reflection even when leaked light enters at an angle less than the critical angle. Furthermore, the reflective surfaces 42, 43 may be parabolically curved or bent so that the leaked light reflected by the reflective surfaces 42, 43 is focused on a continuous portion 71 on the boundary between two adjacent light return elements 41 on the +Y side. This allows the light return section 40 to return light from the light entrance section 10 (light-collecting element 11) to the light guide section 20 via the region between the reflective surfaces 12, 13 and the light guide section 20 without being reflected therefrom, i.e., the leaked light, to the light guide section 20. This allows most of the light entering the light entrance section 10 to be trapped within the light guide section 20 and output from the light output surface 20a.

[0091] In the light guide 1d2 according to the second embodiment and the light guides 1d3 and 1d4 according to the second and third modifications, the light guide section 20 is formed in a plate shape extending in the Y-axis direction perpendicular to the light input direction (Z-axis direction). However, the light guide section 20 may be curved in any direction intersecting the light input direction, such as an arc-shaped or spherical-shell-shaped curve. Furthermore, the light guide section 20 may be curved or bent in any direction from the portion overlapping with the light entrance section 10, or may be formed to extend to the light exit surface 20a by widening or narrowing, or increasing or decreasing its thickness. Thus, light collected by the light entrance section 10 is guided into the light guide section 20 and then reflected by its end surface and guided in any direction toward the light exit surface 20a.

[0092] In addition, the light output from the light exit surface 20a of the light guides 1d2, 1d3, and 1d4 may be input to another light guide (such as an optical fiber) different from the light guides 1d2, 1d3, and 1d4, and output (emitted) at the other end of the other light guide.

[0093] 19A and 19B respectively show the overall configuration of a light guide 100 according to a third embodiment, and 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 guides the collected light to a light exit surface 120a different from the light entrance surface 110a without or with little leakage, and is provided with the light entrance section 110, the light guide section 120, and the boundary section 130. Note that 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.

[0094] 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. The +Z sides of the Y-side surfaces (i.e., the +Y side surface and the -Y side surface) are in contact with each other, and the -Z sides are spaced apart from each other and arranged in parallel in the Y-axis direction. 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 extends 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 (simply referred to as a space) 130s between them, which has a triangular cross section and extends in the X-axis direction.

[0095] 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.

[0096] 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.

[0097] Reflecting surfaces 112 and 113 are positioned on the +Y and −Y sides of light-transmitting portion 114, respectively, and are arranged opposite 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.

[0098] The light guide 120 has a light output surface 120a located on the -Z side of the light input section 110, and is an optical component that guides reflected light reflected by the reflecting surfaces 112 and 113 of the light input section 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 section 110, the length in the Y-axis direction is greater than (or may be equal to) the length of the light input section 110, and the thickness in the Z-axis direction is greater than the thickness of the light input section 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 and functions as a reflective surface that reflects the light guided into the light guide 120 inward.

[0099] 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.

[0100] 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 .

[0101] 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.

[0102] 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 130, may be mirror-finished. Alternatively, a reflective film may be provided using a metal or the like.

[0103] In the third embodiment, the light-entering section 110 is formed by arranging the light-collecting elements 111 in parallel in the Y-axis direction, so that the reflecting surfaces 112, 113 and the light-transmitting sections 114 of the light-entering section 110 are arranged in multiple locations along the Y-axis direction within the light-entering section 110. Accordingly, multiple continuous sections 131 and multiple discontinuous sections 132 are provided at the boundary between the light-entering section 110 and the light-guiding section 120, and multiple continuous sections 131 and multiple discontinuous sections 132 are alternately arranged along the Y-axis direction. Here, the continuous sections 131 have a width A in the Y-axis direction (equal to the width of the light-transmitting sections 114) and are periodically arranged at a pitch P in the Y-axis direction. In this embodiment, the discontinuous sections 132 have a width approximately equal to that of the continuous sections 131 and are arranged between the continuous sections 131. This reduces the aperture ratio A / P to approximately half.

[0104] As shown in FIG. 19B , 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 20 shows the collection of light input into the light guide 1 by the light entrance section 110 and the guidance of the light 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.

[0110] The light guide 100 according to the third embodiment can be manufactured in the same manner as the light guide 1 according to the first embodiment.

[0111] FIG. 21 shows a light guide assembly 100a according to a third 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 entrance surface 110a of the lower light guide 100. A small gap is provided between the light entrance surface 110a of the lower light guide 100 and the −Z surface of the upper light guide 100. The lower light guide 100 is disposed on the opposite side of the light entrance portion 110 of the light guide portion 120 of the upper light guide 100 in the Z-axis direction, and is also an example of a light collecting portion provided to input light that has passed through the upper light guide portion 120.

[0112] 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 .

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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 .

[0119] 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.

[0120] The light guide 100 according to the third 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 the light incident surface 110a into which 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.

[0121] The light guide assembly 100a according to the third 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. This allows most of the light entering the light guide assembly 100a to be trapped within the light guide portion 120 and output from the light exit surface 120a.

[0122] The upper surface (light entrance surface 110a of the light entrance section 110) and the lower surface (-Z surface of the light guide section 120) of the light guide 100 according to the third embodiment may be smooth, which can prevent the accumulation of dust and other particles when the light guide 100 is installed outdoors.

[0123] In the light guide 100 according to the third embodiment, the light guide section 120 is formed in a plate shape extending in the Y-axis direction perpendicular to the light input direction (the Z-axis direction). However, 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.

[0124] In addition, 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) other than the light guide 100, and output (emitted) at the other end of the other light guide.

[0125] 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.

[0126] 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.

[0127] DESCRIPTION OF SYMBOLS 1, 1d, 1d2, 1d3, 1d4...light guide body, 10, 10d...light entrance portion, 10a...light entrance surface, 11, 11d...light collecting element, 12, 13, 14...reflecting surface, 19...parabola, 19a...directrix, 19b...focus, 20, 20d...light guide portion, 20a...light exit surface, 20d...light guide portion, 30, 30d...boundary portion, 30s, 30t...space, 31...continuous portion, 32...discontinuous portion, 40, 40d...light return portion, 40s, 40t...space, 41, 41a, 41b...light return element, 42, 43...reflecting surface, 44, 45...refractive surface, 48...bottom, 49...circle, 49a...focus, 50s...internal space, 51, 52...mold, 53...nested mold, 61, 62, 63 ...mold, 61s, 63s...internal space, 62a...protruding edge, 65...nested, 70...boundary portion, 70s...space, 71...continuous portion, 72...discontinuous portion, 80...incident angle, 99...movement trajectory plane, 100...light guide, 100a, 100b...light guide assembly, 110...light incident portion, 110a...light incident surface, 111...light focusing element, 112, 113...reflecting surface, 114...light-transmitting portion, 120...light guide portion, 120a...light output surface, 120b...-Z end surface, 130...boundary portion, 130s, 130sa, 130sb...space, 131...continuous portion, 132, 132a, 132b...discontinuous portion, I11, I12, I21, I22, I31, I32...light.

Claims

1. A light guide that guides light input from a light entrance surface to a light exit surface different from the light entrance surface and outputs the light from the light exit surface, 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 and output the light from the light exit surface; A continuous portion is 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 with each other, and a discontinuous portion is provided so that the light entrance portion and the light guide portion are spaced apart from each other; A light guide comprising:

2. The light guide body of claim 1 , wherein the continuous portions and the discontinuous portions are each provided in multiple numbers at the boundary between the light entrance portion and the light guide portion, and the continuous portions and the discontinuous portions are alternately arranged along the second direction.

3. The light guide according to claim 2 , wherein the continuous portion and the discontinuous portion are arranged such that a length of the continuous portion is smaller than a length of the discontinuous portion in the second direction.

4. The light guide according to claim 1 , wherein the light entrance portion has a reflecting surface provided to reflect the light input from the light entrance surface toward the continuous portion.

5. The light guide according to claim 4 , wherein the reflecting surface is formed so as to reflect the light, which is input from a direction perpendicular to the light incident surface, toward the continuous portion.

6. The light guide according to claim 5 , wherein the reflective surface is curved or bent on a cross section including the first direction and the second direction.

7. The light guide according to claim 5 , further comprising another reflecting surface disposed opposite the reflecting surface and reflecting the light input from the light incident surface toward the continuous portion.

8. The light guide according to claim 1 , wherein the light entrance portion extends 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 both the first direction and the second direction.

9. The light guide according to claim 8 , wherein the light guide portion is formed to extend in the second direction.

10. The light guide according to claim 9 , wherein an end portion of the light guide portion opposite to the light entrance portion in the first direction is formed in a flat shape.

11. The light guide according to claim 8 , wherein the continuous portion is formed so as to extend in the third direction.

12. The light guide according to claim 11 , wherein the continuous portion is disposed so that the third direction is substantially parallel to a plane including a path of movement of the sun.

13. 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.

14. The light guide of claim 13 , wherein the light entrance portion and the light guide portion are joined by welding.

15. The light guide of claim 1 , wherein the light entrance portion and the light guide portion are formed from the same material.

16. 2. The light guide body of claim 1, wherein the discontinuous portion includes a first discontinuous portion in which a distance between the light entrance portion and the light guide portion is constant along the second direction, and a second discontinuous portion in which a distance between the light entrance portion and the light guide portion is variable along the second direction.

17. the light entrance portion has a reflecting surface provided to reflect the light input from the light entrance surface toward the continuous portion, The light guide according to claim 16 , wherein a surface of the reflecting surface opposite to the light guide portion constitutes an end portion of the second discontinuous portion on the light entrance portion side.

18. The light guide according to claim 1 , further comprising a light collecting section arranged on the opposite side of the light input section with respect to the light guiding section in the first direction so that the light that has passed through the light guiding section is input thereto.

19. 19. The light guide of claim 18, further comprising: other continuous portions arranged at other boundaries of the light guiding portion and the light collecting portion such that the light guiding portion and the light collecting portion are continuous; and other discontinuous portions arranged so that the light guiding portion and the light collecting portion are spaced apart.

20. The light guide according to claim 19 , wherein the light collecting section includes a light returning section that returns the transmitted light that has passed through the light guiding section to the light guiding section.

21. The light guide according to claim 20 , wherein the light returning portion has a further other reflective surface that reflects the passing light toward the other continuous portion.

22. The light guide according to claim 21 , wherein the light returning portion has a refracting surface that refracts the passing light reflected by the further other reflective surface toward the other continuous portion.

23. the light entrance portion has a reflecting surface provided to reflect the light input from the light entrance surface toward the continuous portion, The light guide according to claim 21 , wherein the further other reflective surface of the light return section is arranged offset in the second direction relative to the reflective surface of the light entrance section.

24. the light entrance portion has a reflecting surface provided to reflect the light input from the light entrance surface toward the continuous portion, the other continuous portion and the other discontinuous portion are arranged such that a length of the other continuous portion is shorter than a length of the other discontinuous portion in the second direction, The light guide according to claim 21 , wherein a center of the other continuous portion is arranged to be offset in the second direction relative to the further other reflecting surface of the light return portion and the reflecting surface of the light entrance portion.

25. The light guide according to claim 19 , wherein the continuous portion and the other discontinuous portion are provided to at least partially overlap each other when viewed in the first direction.

26. The light guide element according to claim 19 , wherein the other discontinuous portion is provided such that a distance between the light guide portion and the light collection portion is constant along the second direction.

27. 27. The light guide of claim 1, wherein the light entrance portion has a reflective surface arranged to reflect the light input from the light entrance surface, and the reflective surface is formed in a straight line on a cross section including the first direction and the second direction.

28. The light guide body according to claim 1 , wherein the discontinuous portion is provided such that an end portion of the discontinuous portion facing the light guide portion extends at an angle with respect to the second direction.

Images