Patent Publication Number: US-10324246-B2

Title: Lighting display device and light guide body

Description:
TECHNICAL FIELD 
     The technical field relates to a light guide body and a lighting display device. 
     BACKGROUND ART 
     In the related art, there is a line lighting display device in which light is incident to an edge surface of a light guide body, and the light propagates inside the light guide body through total reflection, and is emitted from an upper surface of the light guide body by prisms or dots disposed on a lower surface of the light guide body. Regarding a structure of prisms or dots formed on a light guide body lower surface, there is a structure in which a section thereof has a simple triangular shape, or a structure in which a recessed and smoothly curved surface is disposed between triangular prisms. For example, there is a light guide body having a shape disclosed in PTL 1 as illustrated in  FIG. 24 . 
     In  FIG. 24 , the reference numeral  6  indicates a light guide body, the reference numeral  8  indicates a prism whose section has a triangular shape, and the reference numeral  9  indicates a recessed and smoothly curved surface disposed between the prisms. If light propagating through light guide body  6  is incident to prisms  8 , the light is emitted to the outside from light guide body  6 , and if the light is incident to curved surfaces  9  between the prisms, the light is diffused. Disposed curved surface  9  diffuses light propagating through light guide body  6 , and prism  8  increases spreading of light emitted from light guide body  6 . 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Patent Unexamined Publication No. 2013-45671 
     SUMMARY 
     However, in the configuration of the related art, if the intensities of light emitted at a location close to and a location separated from a light source are made to be the same as each other in a case where the light guide body is long, a depth of a prism formed on the light guide body lower surface is required to be considerably small since an amount of light propagating through the light guide body is considerably large in the vicinity of the light source in the light guide body. This tendency becomes more remarkable as a light guide body becomes longer. Therefore, in a case where a light guide body is long, very minute prisms are required to be formed in the vicinity of a light source, and thus it is difficult to form prisms. If a depth of a prism is to be increased, it is necessary to increase an arrangement interval of prisms, and this causes a problem that light becomes uneven and thus display quality deteriorates. Thus, particularly, there is a problem in that it is hard to handle a display pattern in which a light source side is dark, and a location becomes brighter as the location becomes more distant from the light source. 
     In order to solve the problem of the related art, one of the objects of an object herein is to easily increase display quality of light. 
     In order to achieve the object, there is provided a light guide body, the light guide body including first dots and second dots. 
     There is provided a lighting display device including the light guide body; and a light source disposed on the first end side. 
     As mentioned above, it is possible to easily increase display quality of light. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram illustrating a line lighting display device in one embodiment. 
         FIG. 2  is a schematic diagram illustrating the line lighting display device in one embodiment. 
         FIG. 3  is a schematic diagram illustrating the line lighting display device in one embodiment. 
         FIG. 4  is a schematic diagram illustrating a second dot formed on a light guide body lower surface in one embodiment. 
         FIG. 5  is a schematic diagram illustrating the second dot formed on the light guide body lower surface in one embodiment. 
         FIG. 6  is a schematic diagram illustrating the second dot formed on the light guide body lower surface in one embodiment. 
         FIG. 7  is a diagram illustrating light which is incident to a light guide body from a light source in one embodiment. 
         FIG. 8  is a diagram illustrating light reflection at the second dot in an XY plane in one embodiment. 
         FIG. 9  is a diagram illustrating a state in which light reflected from the second dot is emitted from the light guide body in a YZ plane in one embodiment. 
         FIG. 10  is a diagram illustrating light reflection at a first dot and the second dot in the XY plane in one embodiment. 
         FIG. 11  is a diagram illustrating light reflection at the first dot and the second dot in the XY plane in one embodiment. 
         FIG. 12  is a diagram illustrating light reflection at the first dot and the second dot in the XY plane in one embodiment. 
         FIG. 13  is a diagram for explaining a relationship between a change in a depth and a change in an amount of emitted light at positions of the first dot and the second dot in the light guide body in one embodiment. 
         FIG. 14  is a diagram for explaining a relationship between a change in a depth and a change in an amount of emitted light at positions of the first dot and the second dot in the light guide body in one embodiment. 
         FIG. 15  is a diagram for explaining a relationship between a change in a depth and a change in an amount of emitted light at positions of the first dot and the second dot in the light guide body in one embodiment. 
         FIG. 16  is a diagram for explaining a relationship between a change in a depth and a change in an amount of emitted light at positions of the first dot and the second dot in the light guide body in one embodiment. 
         FIG. 17  is a diagram illustrating a case where the light guide body is disposed to be curved in one embodiment. 
         FIG. 18  is a diagram illustrating a case where a shape of the light guide body in the YZ plane is a circular shape in one embodiment. 
         FIG. 19  is a diagram illustrating a case where sectional shapes of the first dot and the second dot in the YZ plane are trapezoidal shapes in one embodiment. 
         FIG. 20  is a diagram illustrating arrangement of the first dot and the second dot and a change in an amount of emitted light in a longitudinal direction of the light guide body in one embodiment. 
         FIG. 21  is a diagram illustrating arrangement of the first dot and the second dot and a change in an amount of emitted light in a longitudinal direction of the light guide body in one embodiment. 
         FIG. 22  is a diagram illustrating a state in which the first dot and the second dot are arranged in two rows on a light source side in the longitudinal direction of the light guide body in one embodiment. 
         FIG. 23  is a diagram illustrating forms of the first dot and the second dot which are arranged in two rows on the light source side in the longitudinal direction of the light guide body. 
         FIG. 24  is a diagram illustrating a prism shape of a line lighting display device of the related art disclosed in PTL 1. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments will be described with reference to the drawings. 
     Embodiment 1 
       FIGS. 1 to 3  are schematic diagrams illustrating a line lighting display device in one embodiment.  FIG. 1  is a diagram illustrating light guide body  104  in a longitudinal direction thereof, and  FIG. 2  is a diagram in which light guide body  104  is viewed from an arrow A direction in  FIG. 1 .  FIG. 3  is a diagram in which light guide body  104  illustrated in  FIG. 1  is viewed from a Y axis direction. 
     In  FIG. 1 , as coordinate axes, the drawing surface rightward direction is taken as an X axis, the upper direction is taken as a Y axis, and the drawing surface depth direction is taken as a Z axis. 
     Light source  101  is formed of an LED or the like. Light source board  102  is provided with electrical wirings for light source  101 , and light source  101  is disposed thereon. A surface of light source board  102  on which light source  101  is disposed is coated with white paint or the like so as to increase light reflectance. 
     Reflector  103  is disposed to surround light source  101  and light guide body  104 , and prevents light from light source  101  from leaking to the outside and thus the light is emitted inward of light guide body  104 . Reflector  103  has an inner surface made of a material with high reflectance. For example, the inner surface is a diffusion surface with high reflectance made of a resin having fine bubbles, or is coated with white paint. 
     Light guide body  104  is made of a material having high light transmittance, and has a smoothly curved or linear long rod shape. A material of light guide body  104  is, for example, a resin such as acryl or polycarbonate, or glass. Since light guide body  104  is disposed so that the X axis direction is a longitudinal direction, and light is incident thereto from light source  101 , the light is incident from an edge surface on a side where light source  101  is provided, that is, from a negative X axis direction. Light guide body upper surface  113  is a surface of light guide body  104  in a positive Y axis direction. Light guide body upper surface  113  has an aspherical lens shape in a YZ plane, and a focal point position is located at the bottom center of second dot  108  in contact with light guide body lower surface  112 , second dot  108  being formed on light guide body lower surface  112  which is an opposite surface to light guide body upper surface  113 . Light which is reflected at the second dot and is emitted from light guide body upper surface  113  is converted into substantially parallel light. 
     In  FIG. 2 , a plurality of grooves  111  are formed along the X axis direction on light guide body upper surface  113 . Grooves  111  are disposed so as not to overlap each other with an interval, that is, so as to leave the aspherical lens shape of light guide body upper surface  113 . A shape of groove  111  is a spherical lens shape or an aspherical lens shape having a focal length which is different from that of the aspherical lens shape of light guide body upper surface  113 . For example, a sectional shape thereof in the YZ plane is a recessed circular arc shape. Grooves  111  diffuse light emitted from second dot  108  of light guide body lower surface  112 . 
       FIGS. 4 to 6  are schematic diagrams illustrating the second dot formed on the light guide body lower surface in one embodiment. 
     As illustrated in  FIG. 4 , light guide body lower surface  112  is a surface of light guide body  104  in the negative Y axis direction. A plurality of first dots  106  and a plurality of second dots  108  are formed on light guide body lower surface  112 . In first dots  106  and second dots  108  formed on light guide body lower surface  112 , depths of the dots may change according to a distance from a light source side edge surface of light guide body  104 , and overlapping between the first dot and the second dot or a gap between the first dot and the second dot may change. 
     As illustrated in  FIGS. 1 and 3 , arrangement  140  indicates arrangement of the first dots and second dots arranged on light guide body lower surface  112 . 
     In  FIG. 3 , arrangement  140  of the first dots and the second dots is disposed near the center of light guide body lower surface  112  of light guide body  104  along light guide body  104 . 
       FIGS. 4 to 6  are diagrams illustrating states of first dot  106  and second dot  108  formed on light guide body lower surface  112 . In  FIGS. 4 to 6 , the same constituent elements as in  FIGS. 1 to 3  are given the same reference numerals, and description thereof will be omitted. 
       FIG. 4  illustrates first dot  106  and second dot  108  at position  105   a  on light guide body lower surface  112  in the vicinity of light source  101  in  FIG. 1 .  FIG. 5  illustrates first dot  106  and second dot  108  at position  105   b  on light guide body lower surface  112  in the vicinity of the center of light guide body  104  in  FIG. 1 , and  FIG. 6  illustrates first dot  106  and second dot  108  at position  105   c  on light guide body lower surface  112  in the vicinity of an opposite side of light guide body  104  to the light source in  FIG. 1 . 
     In  FIG. 4 , first dot  106  protrudes inward of light guide body  104  with respect to light guide body lower surface  112 , and forms a recessed dot when viewed from the outside of the light guide body. First dot  106  has a triangular pyramid shape with a round ridge line portion and the center in the X direction, and inclined surface  107  on the light source side forms small angle θ 1  with light guide body lower surface  112  in the XY plane. Angle θ 1  is preferably a small angle which is more than 0 degrees and is equal to or less than about 10 degrees. 
     Second dot  108  protrudes inward of light guide body  104  with respect to light guide body lower surface  112  and forms a recessed dot when viewed from the outside of light guide body  104 . Second dots  108  are disposed at the substantially same interval in the longitudinal direction, that is, the X axis direction on light guide body lower surface  112 . Second dot  108  is a rotation symmetric body with a central axis in the Y axis direction, a tip end thereof is curved surface  109 , and side surface  110  thereof has a conical shape and forms angle θ 2  with light guide body lower surface  112 . If angle θ 2  is set to an angle of about 45° to 70°, when light propagating through the light guide body is reflected at side surface  110  of the second dot, the light is emitted in a front direction of light guide body  104 , that is, the Y axis direction. 
     As illustrated in  FIGS. 1 and 4 , at position  105   a  close to light source  101  on light guide body lower surface  112 , first dot  106  and second dot  108  form a pair, and first dot  106  and second dot  108  are disposed in this order from light source  101  side in each pair. In other words, second dot  108  is disposed further in the positive X axis direction than first dot  106 . A part of second dot  108  on light source  101  side, that is, in the negative X axis direction may be disposed to overlap first dot  106 . In other words, the mutual recessed shapes of first dot  106  and second dot  108  overlap each other. If a length of first dot  106  in the XY plane on light guide body lower surface  112  is indicated by L 1 , and a length of second dot  108  is indicated by L 2 , a relationship of L 1 &gt;L 2  is satisfied. A relationship between angle θ 1  of first dot  106  and angle θ 2  of side surface  110  of second dot  108  with respect to light guide body lower surface  112  satisfies θ 1 &lt;θ 2 . A sectional shape of the first dot and a sectional shape of the second dot in the YZ plane are substantially the same as each other, and first dot  106  is disposed to be slightly larger than second dot  108 . First dot  106  is formed so that depth h 1  is reduced as the first dot becomes more distant from light source  101 . On the other hand, second dot  108  is formed so that depth h 2  is increased as the second dot becomes more distant from light source  101 . In a pair of first dot  106  and second dot  108 , a relationship of h 1 &gt;h 2  is satisfied. At position  105   a , a difference between h 1  and h 2  may be gradually reduced as a location becomes more distant from light source  101 . 
     In  FIG. 5 , first dot  106  is separated from second dot  108 , and depth h 1  of first dot  106  is larger than depth h 2  of second dot  108 , that is, a relationship of h 1 &lt;h 2  is satisfied. At position  105   b , a difference between h 1  and h 2  may be gradually increased as a location becomes more distant from light source  101 . A gap between first dot  106  and second dot  108  may be increased as a location becomes more distant from light source  101 . In the description of  FIG. 4 , as an example, a description has been made of a case where first dot  106  overlaps second dot  108  in the vicinity of light source  101 , but the first dot and the second dot is not necessarily required to overlap each other. That is, first dot  106  and second dot  108  may be disposed to be sufficiently close to each other, and a gap therebetween may be increased as a location becomes more distant from the light source. 
     As illustrated in  FIG. 6 , at position  105   c , first dot  106  is not present, and only second dot  108  is present. 
     In  FIG. 1 , position  105   a  is located on lower surface  112  of light guide body  104  in the vicinity of light source  101 , position  105   b  is located on lower surface  112  in the vicinity of the center of light guide body  104 , and position  105   c  is located on lower surface  112  in the vicinity of the edge surface of light guide body  104  on the opposite side to light source  101 . 
     A description will be made of an operation of the line lighting display device configured in the above-described way. 
       FIG. 7  is a diagram illustrating a portion where light is incident to light guide body  104  from light source  101  in  FIG. 1 . In  FIG. 7 , the same constituent elements as in  FIG. 1  are given the same reference numerals, and description thereof will be omitted. 
     Most of light emitted from light source  101  is directly incident to light guide body  104  from the edge surface of light guide body  104  in the negative X axis direction. Among light beams emitted from light source  101 , light beams which are not directly incident to light guide body  104  and are reflected at reflector  103  or light source board  102  are diffused and reflected, and some of the light beams are incident to reflector  103  or light source board  102  again, and the others are incident from the edge surface of light guide body  104  in the negative X axis direction. Light beams  120  which are incident from the edge surface of light guide body  104  in the negative X axis direction travel inside light guide body  104  in the X axis direction, and are totally reflected at interfaces of light guide body  104 , that is, light guide body upper surface  113  and light guide body lower surface  112  so as to propagate. Since light guide body  104  has a linear shape or a smoothly curved shape, light which is incident from the edge surface in the negative X axis direction is totally reflected so as to propagate without leaking out of light guide body  104 . 
       FIG. 8  is a diagram illustrating a state in which light is emitted from light guide body  104  by second dot  108  formed in light guide body  104 . In  FIG. 8 , the same constituent elements as in  FIG. 1  are given the same reference numerals, and description thereof will be omitted. 
     If light beams  120  propagating through light guide body  104  are incident to and reflected at second dot  108 , an angle of light beams  120  greatly changes, and thus light beams  120  are converted into light beams  121  with angles close to the Y axis direction. 
     Since second dot  108  has a triangular pyramid shape in which the tip end thereof is curved surface  109 , and an angle formed between side surface  110  and light guide body lower surface  112  is angle θ 2 , reflected light at side surface  110  with a large inclined angle becomes reflected light toward light source  101  (refer to  FIG. 1 ) side, that is, light beams with angles approximately from the Y axis direction in the negative X axis direction in the XY plane. Reflected light at curved surface  109  of the tip end becomes reflected light toward the opposite side to light source  101  (refer to  FIG. 1 ), that is, light beams with angles approximately from the Y axis direction in the positive X axis direction in the XY plane. As mentioned above, curved surface  109  is provided at the tip end of second dot  108  is provided in addition to side surface  110 , and thus light beams in which light is widely spread in the XY plane can be formed. An amount of light emitted from light guide body  104  in the Y axis direction due to light reflection at second dot  108  is approximately proportional to a depth of second dot  108 . Therefore, an amount of light propagating through light guide body  104  is large at a location close to light source  101 , and, at a location becoming distant from light source  101 , some of light beams  120  are emitted outward of light guide body  104  due to second dot  108 , and thus an amount of light propagating through light guide body  104  is gradually reduced. Thus, in a case where the entire light guide body  104  is caused to emit light uniformly with the same luminance, if there is no first dot  106 , it is necessary to reduce depth h 2  of the second dot on light source  101  side, and to increase depth h 2  of second dot  108  as a location becomes more distant from light source  101 , in order to reduce an amount of light emitted from light source  101  side. As a length of light guide body  104  increases, it is necessary to reduce a depth of second dot  108  on light source  101  side. In order to increase depth h 2  of second dot  108 , an arrangement interval of second dots  108  in the X axis direction is required to be increased, and thus light emitted from light guide body  104  causes bright spots at a rough interval to be viewed, that is, unevenness to be viewed, and thus display quality deteriorates. 
       FIG. 9  is a diagram illustrating light beams in light guide body  104  in the YZ plane. In  FIG. 9 , the same constituent elements as in  FIGS. 1 and 8  are given the same reference numerals, and description thereof will be omitted. Light beams  121  reflected at second dot  108  formed on light guide body lower surface  112  are emitted from second dot  108  as light beams  121  which are spread centering on the Y axis direction. Light guide body upper surface  113  has a lens shape in the YZ plane, and the lens shape is formed so that a focal point position of the lens is located at the bottom center of second dot  108 . Generally, a light beam passing through the focal point position of the lens becomes a light beam which is parallel to a lens optical axis, that is, a straight line connecting the center of the lens to the lens focal point position, due to the lens. As a position of a light beam becomes more distant from the focal point position of the lens, the light beam is emitted with a large angle with respect to the lens optical axis. Since a width of second dot  108  in a YZ section is sufficiently smaller than light guide body upper surface  113  having the lens shape, a light beam reflected at and emitted from second dot  108  becomes a light beam passing through a position close to the focal point position of the lens shape of light guide body upper surface  113 , and thus light emitted from light guide body upper surface  113  is emitted as light similar to parallel light. Since grooves  111  are formed on light guide body upper surface  113 , among light beams emitted from second dot  108 , light beams which are incident to grooves  111  are diffused so as to become light beams which are spread in the YZ plane. Since grooves  111  are disposed with an interval on light guide body upper surface  113 , light emitted from second dot  108  is emitted as light beams in which widely spread light beams emitted from grooves  111  and directional light beams which are parallel to the Y axis direction are combined with each other. With this configuration, it is possible to perform lighting in which display with high luminance can be displayed, and display is viewed at a wide angle in the YZ plane, when viewed from the Y axis direction. 
       FIGS. 10 to 12  are diagrams illustrating a state in which light is emitted from light guide body  104  by first dot  106  and second dot  108  of light guide body  104 . In  FIGS. 10 to 12 , the same constituent elements as in  FIG. 1  are given the same reference numerals, and description thereof will be omitted. 
       FIG. 10  illustrates light beams at position  105   a  on light guide body lower surface  112  close to the light source in light guide body  104  in  FIG. 1 . If light beams  120  propagating through light guide body  104  are incident to inclined surface  107  of first dot  106  on the light source side, angle θ 1  of inclined surface  107  on the light source side is small, and thus an azimuth change of reflected light beams is small, and most of the light beams are totally reflected inside light guide body  104  so as to continuously propagate. 
       FIG. 11  illustrates a light amount distribution right after first dot  106  in the YZ plane at position  130  in the light guide body in  FIG. 10 . Light beams  120  in light guide body  104  propagate while being totally reflected at the interfaces of light guide body  104 , that is, light guide body upper surface  113  and light guide body lower surface  112 , and thus a light amount distribution of light guide body  104  in the YZ plane is substantially uniform. If there is first dot  106  on light guide body lower surface  112 , a location right after first dot  106  is shielded from light beams, and thus an amount of light is reduced in the location. The light beams propagating through light guide body  104  are spread centering on the X axis direction, and thus the light amount distribution is a distribution in which an amount of light is gradually reduced from the outer shape of first dot  106  inward thereof in the YZ plane at position  130  right after first dot  106 . 
     Second dot  108  is disposed at a location where an amount of light is reduced due to first dot  106  right after first dot  106  in the advancing direction of light beams  120 . If first dot  106  is provided compared with the absence of first dot  106 , in a case where the same amount of light is emitted from light guide body  104 , an amount of emitted light can be reduced even if depth h 2  of the second dot is not reduced, and thus depth h 2  of the second dot can be increased. 
     Since an amount of light propagating through light guide body  104  is large in the vicinity of light source  101 , if there is no first dot  106 , the number of light beams  121  reflected at second dot  108  and emitted from light guide body  104  increases, and thus the number of light beams  120  propagating through light guide body  104  is reduced. Thus, in order to suppress reflection at second dot  108 , a depth of second dot  108  is required to be considerably small, and thus it is difficult to manufacture light guide body  104 . In contrast, if first dot  106  is provided, it is not necessary to form second dot  108  to be shallow, and thus it becomes easier to manufacture light guide body  104 . If first dot  106  is provided, a depth of the easily manufactured second dot can be secured, and it is possible to reduce an amount of light emitted from light guide body  104  due to second dot  108  even in the vicinity of light source  101  in which the number of light beams propagating through light guide body  104  is large. 
       FIG. 12  illustrates light beams at position  105   b  on light guide body lower surface  112  in the vicinity of the center of light guide body  104  in  FIG. 1 . 
     Depth h 1  of first dot  106  is reduced as the first dot becomes more distant from light source  101  side, but, conversely, depth h 2  of second dot  108  is increased. Therefore, the depth of first dot  106  is smaller than the depth of second dot  108  at position  105   b  on light guide body lower surface  112 . If a gap between first dot  106  and second dot  108  is increased as a location becomes more distant from light source  101 , second dot  108  is hardly influenced by a reduction in an amount of light due to first dot  106 . Light beams  120  propagating through light guide body  104  are gradually emitted as light beams  121  from light guide body  104  in the Y axis direction due to second dot  108  disposed on light guide body lower surface  112 , and an amount of light propagating through light guide body  104  is reduced. Thus, it is necessary to increase an amount of light emitted from light guide body  104  by increasing a depth of second dot  108 , but a depth of first dot  106  is reduced, and overlapping between first dot  106  and second dot  108  in the X direction in the YZ plane is also reduced. Therefore, an amount of light which is incident to second dot  108  is increased, and thus an increase of a depth of second dot  108  may be slight. 
     At position  105   c  close to the edge surface on the opposite side to the light source on light guide body lower surface  112  in  FIG. 1 , only second dot  108  is disposed on light guide body lower surface  112 , and thus light beams  121  are reflected at second dot  108  so as to be emitted from light guide body  104  in the same manner as in  FIG. 8 . 
       FIGS. 13 to 16  are diagrams for explaining a relationship between changes in depths of first dot  106  and second dot  108  and a change in an amount of light emitted from light guide body  104  in the Y axis direction.  FIG. 13  is a diagram illustrating depth h 1  of first dot  106  and depth h 2  of second dot  108  in gradation display in which an amount of emitted light on light source  101  (refer to  FIG. 1 ) side is small, an amount of emitted light in the vicinity of the center of light guide body  104  is large, and an amount of emitted light of light guide body  104  on the opposite side to light source  101  is small.  FIG. 14  is a diagram illustrating a light emission amount distribution regarding light emitted from light guide body  104  viewed from the Y axis direction at the depths of first dot  106  and second dot  108 , corresponding to  FIG. 13 . 
     Depth h 1  of first dot  106  on light source  101  side is larger than depth h 2  of second dot  108 , that is, a relationship of h 1 &gt;h 2  is satisfied, and thus an amount of light reflected at second dot  108  (refer to  FIG. 1 ) and emitted from light guide body  104  can be reduced. As a location becomes more distant from light source  101 , depth h 1  of first dot  106  is reduced, depth h 2  of second dot  108  is increased, and thus it is possible to increase an amount of light emitted from light guide body  104  over the vicinity of the center of light guide body  104 . An amount of light propagating through light guide body  104  is reduced from the vicinity of the center of light guide body  104 , and thus an amount of light emitted from light guide body  104  is gradually reduced. A position where an amount of light emitted from light guide body  104  is the maximum may be changed by adjusting depth h 1  of first dot  106  and depth h 2  of second dot  108  from the light source to the vicinity of the center of light guide body  104 . 
       FIG. 15  is a diagram illustrating depths of first dot  106  and second dot  108  at which an amount of light emitted from light guide body  104  in the Y axis direction is substantially uniform in the entire light guide body.  FIG. 16  is a diagram illustrating a distribution of an amount of light emitted from light guide body  104 , viewed from the Y axis direction at depth h 1  of first dot  106  and depth h 2  of second dot  108 , corresponding to  FIG. 15 . 
     Depth h 1  of first dot  106  on light source  101  side is made to be smaller than depth h 2  of second dot  108 , and thus it is possible to adjust an amount of light emitted from light guide body  104 . Depths of first dot  106  and second dot  108  are set not to be too small. As a location becomes more distant from light source  101 , depth h 1  of first dot  106  is reduced, depth h 2  of second dot  108  is increased, and thus an amount of light emitted from light guide body  104  is adjusted. Therefore, light can be uniformly emitted from the entire light guide body  104 . 
     As mentioned above, a plurality of pairs of first dots  106  and second dots  108  are formed in light guide body  104 , and inclined surface  107  and side surface  110  as side surfaces of first dot  106  and second dot  108  on the light source  101  side are formed so that an inclination of side surface  110  with respect to light guide body lower surface  112  is larger than that of inclined surface  107 . In the vicinity of light source  101 , depth h 1  of first dot  106  is larger than depth h 2  of second dot  108 , and, as a location comes closer to the end on the opposite side to light source  101 , depth h 1  of first dot  106  is reduced, and depth h 2  of second dot  108  is increased. Depth h 1  of first dot  106  may be gradually reduced as a location becomes more distant from light source  101 , and depth h 2  of second dot  108  may be gradually increased as a location becomes more distant from light source  101 . First dot  106  may not be provided at the end on the opposite side to light source  101 . A length of inclined surface  107  may be reduced as a location becomes more distant from light source  101 , and a length of the side surface may be increased as a location becomes more distant from light source  101 . According to such a configuration, a depth of second dot  108  can be increased as a result of disposing first dot  106  right before second dot  108  on light guide body lower surface  112  on light source  101  side, and thus it is possible to easily manufacture a light guide body. Since an amount of light emitted from light guide body  104  can be gradually increased from a state close to 0 while securing a sufficient depth causing second dot  108  to be easily manufactured, an amount of emitted light is reduced in the vicinity of light source  101  in which the number of propagating light beams is large, and an amount of irradiation light is increased in a region which is separated from light source  101  in which the number of propagating light beams is small. Therefore, an amount of irradiation light can be uniform in the entire of light guide body  104 , and thus it is possible to improve display quality. Since an interval between second dots  108  in the X axis direction can be reduced, it is possible to perform smooth display and thus to improve display quality. 
     In  FIG. 1 , light guide body  104  is formed in a linear shape, but, as illustrated in  FIG. 17 , may be formed in a curved shape in a three-dimensional space. 
     An arrangement interval of second dots  108  is equal, but the interval may be changed. 
     The number of grooves  111  formed on light guide body upper surface  113  in the longitudinal direction is not limited to three, and may be one, two, or four or more. Alternatively, in a case where spreading of light emitted from light guide body  104  is reduced, grooves  111  may be omitted. 
     A sectional shape of first dot  106  in the YZ plane may be similar to that of second dot  108 , but may not be similar if first dot  106  is slightly larger than second dot  108 . The tip end of inclined surface  107  of first dot  106  on the light source side may be formed in a shape with an acute angle instead of a curved shape. 
     Second dot  108  has a rotation symmetric shape centering on the Y axis, but the central axis of the dot may be inclined from the Y axis. For example, the central axis may be inclined in the negative X axis direction or the positive X axis direction in the XY plane. 
     Regarding a sectional shape of light guide body  104  in the YZ plane, the upper surface has an aspherical lens shape, but, as illustrated in  FIG. 18 , a YZ section of light guide body  104  may have a circular shape, that is, light guide body upper surface  113  and light guide body lower surface  112  may have a semicircular shape. Since light guide body upper surface  113  has an aspherical lens shape, and grooves  111  are used, spreading of light in the YZ plane can be adjusted from a state of being close to parallel light, but, if a sectional shape of light guide body  104  is a circular shape, light is widely spread even though spreading of light in the YZ plane cannot be made in a state of being close to parallel light, and thus spreading of light can be used for various applications. 
     Second dot  108  has a small sectional area in the YZ plane since the tip end thereof is curved surface  109 , and side surface  110  thereof is a conical surface, and this is advantageous in that a dot depth can be increased, but, as illustrated in  FIG. 19 , a sectional shape of second dot  108  in the YZ plane may be trapezoidal shape  138 , and a sectional shape of the first dot in the YZ plane may be trapezoidal shape  136 . 
     Arrangement  140  of first dot  106  and second dot  108  are disposed at the center of light guide body  104 , but, as illustrated in  FIG. 20 , may be changed in a sine wave shape, and thus an amount of emitted light in the Y axis direction can be changed in a sine wave shape. Alternatively, as illustrated in  FIG. 21 , arrangement  140  is obliquely disposed with a small angle with respect to the X axis in a short length, and thus an amount of emitted light in the Y axis direction can be changed. In other words, arrangement  140  is divided into a plurality of lines, and each arrangement may be disposed with an angle with respect to the X axis direction. 
     A light-transmissive cover may be further provided to surround light guide body  104  and light source  101 , and a thin emboss may be formed on a rear surface of the light-transmissive cover, that is, a surface facing light guide body  104  so that light is weakly emitted from the cover. 
     A plurality of cylindrical surfaces having a cylindrical axis which is parallel to the Z axis direction may be formed on the rear surface of the light-transmissive cover so that a spread angle of light emitted from light guide body  104  is increased. 
     As illustrated in  FIG. 22 , when viewed from the Y axis, arrangement  140  of first dot  106  and second dot  108  may not be disposed in one row, and arrangement  140  in a region ranging over a predetermined distance from light source  101  (refer to  FIG. 1 ) may be disposed in two rows, and may be combined into one row as a location becomes more distant from light source  101 .  FIG. 23  is an enlarged view of first dot  106  and second dot  108  illustrated in  FIG. 22 . In  FIG. 23 , first dots  106  and second dots  108  at light guide body positions  141   a ,  141   b ,  141   c  and  141   d  in  FIG. 22  are illustrated, and first dots  106  and second dots  108  in the middle are not illustrated. 
     As exemplified in  FIG. 23 , pairs of first dots  106  and second dots  108  are arranged in two rows in the Z axis direction at light guide body position  141   a . The centers of first dot  106  and second dot  108  are slightly deviated. The centers are deviated in a direction of a gap between first dots  106  being larger than a gap between second dots  108  in the Z axis direction. At light guide body position  141   b , as a location becomes more distant from light source  101 , first dot  106  becomes shallower and smaller, and second dot  108  becomes deeper and larger. At light guide body position  141   c , first dot  106  is removed, and two second dots  108  in the Z axis direction overlap each other. At light guide body position  141   d , second dots  108  are completely integrated into a dot. In other words, third dots corresponding to second dots  108  are arranged on the positive X axis direction with light guide body position  141   c  as a boundary. At light guide body positions  141   a ,  141   b ,  141   c  and  141   d , second dots  108  are disposed so that arrangement widths w of second dots  108  in the Z axis direction are substantially the same as each other. Here, in a case where second dot  108  is formed of a dot as at light guide body position  141   d , arrangement width w of second dots  108  indicates a width thereof in the Z axis direction, and, in a case where second dot  108  is formed of two dots as at light guide body positions  141   a ,  141   b  and  141   c , arrangement width w indicates a distance between outer circumferences of the two dots in the Z axis direction. As mentioned above, width w of second dot  108  in the Z axis direction is made to be substantially constant regardless of a distance from light source  101 , and thus spreading of light emitted from light guide body  104  in the Y axis direction can be made to be substantially uniform. This is because, in the YZ plane, light guide body upper surface  113  (refer to  FIG. 1 ) has a lens shape, and a focal point position of the lens is disposed approximately near the bottom center of second dot  108  formed on light guide body lower surface  112  (refer to  FIG. 1 ), and thus reflected light at second dot  108  becomes a light beam which is parallel to the Y axis direction in light guide body upper surface  113 . At this time, spreading of light in light guide body upper surface  113  changes due to the width of the second dot in the Z axis direction. If the width of the second dot in the Z axis direction is small, light is approximated to parallel light, and if the width in the Z axis direction is large, light becomes widely spread light. Since second dots  108  are disposed in two rows on light source  101  side, a width of the outer shape of the second dots is increased, and a width of the outer shape of second dots  108  in the longitudinal direction of light guide body  104  is made to be constant, spreading of light emitted from light guide body upper surface  113  can be made to be substantially uniform. 
     Light guide body  104  may have a configuration in which there is a cavity inside thereof, and there is no cavity inside thereof, and may have a configuration in which a light beam propagates. In a case where there is no cavity inside the light guide body, first dot  106  and second dot  108  are formed on light guide body lower surface  112  by recessing the surface of light guide body  104 . In a case where there is a cavity inside the light guide body, first dot  106  and second dot  108  may be formed on light guide body lower surface  112  by recessing the surface of light guide body  104 , and may be formed of protrusions which protrude in an internal direction of the cavity on light guide body lower surface  112 . In a case of the protrusion, a depth of the dot corresponds to a height of the protrusion. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure is suitable for a light guide body which can easily increase display quality of light even in a case of a long light guide body and can perform lighting by reflecting a light beam from a light source, and a line lighting display device or the like having the light guide body.