JP2015026600A - Light guide plate and illumination apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide plate capable of making an extraction element for extracting light inconspicuous.SOLUTION: A light guide plate 30 includes an extraction light guide layer 40 having a pair of principal planes 41a, 41b. The extraction light guide layer 40 includes a base part 45 having a pair of principal planes 46a, 46b and a plurality of light diffusion parts 50 arranged in the base part. When a ratio of height to the width of the light diffusion part 50, i.e. an aspect ratio of the light diffusion part 50 is high, the light diffusion part is effectively functioned as an extraction element for extracting light from the light guide plate 30 while preventing conspicuousness of the light diffusion part 50 when observing the light guide plate 30 from a normal direction to a plate surface of the extraction light guide layer 40.

Description

  The present invention relates to a light guide plate and a lighting device including the light guide plate, and more particularly to a light guide plate and a lighting device that can make an extraction element for extracting light inconspicuous.

  For example, as disclosed in Patent Document 1, an illumination device using a light guide plate and a light source arranged so as to face a side surface of the light guide plate is known. In this illuminating device, the light emitted from the light source is repeatedly reflected on the pair of main surfaces of the light guide plate and travels through the light guide plate. On the main surface on the back side of the light guide plate, a diffusible substance is provided by patterning. The light traveling in the light guide plate is incident on the main surface of the light guide plate at an angle less than the total reflection critical angle by being changed in the traveling direction by the diffusible substance, and as a result, the light from the light guide plate through the main surface. It comes out. That is, the diffusive substance functions as an extraction element for extracting light from the light guide plate. And the pattern of a diffusive substance is determined so that the desired emitted light quantity distribution along a light guide direction can be implement | achieved. As a typical example, in the case where the amount of emitted light from each region along the light guide direction is made uniform, in view of the tendency that the amount of emitted light tends to decrease in a region separated from the light source, the area as the distance from the light source increases. The pattern of the diffusible material is determined so that is increased.

JP-A-10-160938

  However, the conventional lighting device using the light guide plate has a problem in that a diffusible substance for controlling the amount of light emitted from each region is visually recognized. In particular, when the diffuse reflective material is patterned, the pattern of the diffusive material is visually recognized, and the conventional lighting device has a problem in appearance such as a decrease in design and a loss of luxury. The range of use has been limited.

  The present invention has been made in consideration of the above points, and an object thereof is to provide a light guide plate capable of making an extraction element for extracting light inconspicuous, and an illumination device including the light guide plate. To do.

The first light guide plate according to the present invention comprises:
A base portion having a pair of main surfaces and a light incident side surface formed of a portion located on one side in the first direction among the side surfaces between the pair of main surfaces;
A plurality of light diffusion portions provided in the base portion;
A take-out light guide layer.

In the first light guide plate according to the present invention, any two light diffusing portions adjacent to each other in the first direction include a separation distance d along the first direction of the two light diffusing portions and the extraction light guide layer. The heights h ₁ and h ₂ of the light diffusion portions of the two lights along the normal line direction, the refractive index n of the extraction light guide layer, and the extraction light guide layer from the one main surface side. refractive index and n _L of adjacent layers, may satisfy the following equation was used.
tan (Arcsin (n _L / n)) ≤ d / (h ₁ + h ₂ )

  In the first light guide plate according to the present invention, the height of the light diffusion portion along the normal direction of the extraction light guide layer may not be constant.

  In the first light guide plate according to the present invention, the height of the at least one light diffusion portion along the normal direction of the extraction light guide layer is located on one side in the first direction with respect to the one light diffusion portion. It may be higher than the height along the normal direction of the extraction light guide layer of at least one other light diffusion portion.

  In the first light guide plate according to the present invention, the height along the normal direction of the extraction light guide layer of any one light diffusing portion is one side in the first direction from the one light diffusing portion. You may make it become more than the height along the normal line direction of the said extraction light guide layer of the other light-diffusion part located.

  The first light guide plate according to the present invention further includes a low refractive index layer disposed adjacent to the extraction light guide layer, and the refractive index of the low refractive index layer is the base portion of the extraction light guide layer. The refractive index may be lower.

  The first light guide plate according to the present invention further includes a cover layer disposed on a side of the low refractive index layer opposite to the extraction light guide layer, and the low refractive index layer includes the extraction light guide layer and the cover layer. It may be a layer for joining the cover layer.

  The first light guide plate according to the present invention further includes a cover layer disposed on a side of the low refractive index layer opposite to the extraction light guide layer, and the cover layer includes the base of the extraction light guide layer. It may have higher scratch resistance than the part.

  In the first light guide plate according to the present invention, a width of the light diffusion portion along the first direction may be constant between the plurality of light diffusion portions included in the extraction light guide layer.

  In the first light guide plate according to the present invention, the arrangement pitch of the light diffusion portions along the first direction may be constant among the plurality of light diffusion portions included in the extraction light guide layer.

  In the first light guide plate according to the present invention, the light diffusion portion may have an aspect ratio of 0.1 or more.

  In the first light guide plate according to the present invention, the base portion is formed with a plurality of grooves at intervals in the first direction on one main surface of the pair of main surfaces, It may be provided in the groove.

  In the first light guide plate according to the present invention, the light diffusion portion may include a main portion and a diffusion component dispersed in the main portion. The diffusion component may be white particles, for example, acrylic resin particles to which titanium oxide is added. The acrylic resin particles may be contained in the light diffusion part at a weight percentage of 20% to 30%. The white particles may have an average particle diameter (average diameter) of 1 μm or more and 30 μm or less. The cross-sectional area of the light diffusing part in the cross section orthogonal to the normal direction of the light guide plate may be larger than the square of the average particle diameter of the white particles. The width of the light diffusion portion along the first direction may be greater than or equal to an average particle size (average diameter).

  In the first light guide plate according to the present invention, each light diffusing portion may extend linearly in a direction non-parallel to the first direction.

A first lighting device according to the present invention comprises:
Any of the first light guide plates according to the invention described above;
And a light source disposed to face the light incident side surface of the light guide plate.

The second light guide plate according to the present invention comprises:
A first main surface and a second main surface facing each other; and a light incident side surface comprising a portion located on one side in the first direction among the side surfaces between the first main surface and the second main surface; A led light layer having,
A low refractive index layer provided on the first main surface of the main light layer and having a refractive index lower than that of the main light layer;
An extraction light guiding layer laminated with the main light layer from the low refractive index layer side,
The first main surface includes a first region and a second region, and the low refractive index layer is provided only on the first region on the first main surface,
The extraction light guide layer has a plurality of extraction elements arranged in the first direction, each of which has a plurality of extraction elements that change the traveling direction of light from the main light layer,
The extraction element is provided in a region facing both the first region and the second region.

  In the second light guide plate according to the present invention, the extraction light guide layer further includes a base part having a pair of main surfaces, and the extraction element is a light diffusion part provided in the base part. Also good. In such a second light guide plate, the light diffusing portion may include a main portion and a diffusion component dispersed in the main portion. The diffusion component may be white particles, for example, acrylic resin particles to which titanium oxide is added. The acrylic resin particles may be contained in the light diffusion part at a weight percentage of 20% to 30%. The white particles may have an average particle diameter (average diameter) of 1 μm or more and 30 μm or less. The cross-sectional area of the light diffusing part in the cross section orthogonal to the normal direction of the light guide plate may be larger than the square of the average particle diameter of the white particles. The width of the light diffusion portion along the first direction may be greater than or equal to an average particle size (average diameter).

  In the second light guide plate according to the present invention, a height of the extraction element along a normal direction of the extraction light guide layer may not be constant.

  In the second light guide plate according to the present invention, the height of the at least one extraction element along the normal direction of the extraction light guide layer is at least located on one side in the first direction with respect to the one extraction element. You may be higher than the height along the normal line direction of the said extraction light guide layer of one other extraction element.

  In the second light guide plate according to the present invention, the height along the normal direction of the extraction light guide layer of any one extraction element is located on one side in the first direction with respect to the one extraction element. It may be more than the height along the normal direction of the extraction light guide layer of another extraction element.

  In the second light guide plate according to the present invention, the extraction light guide layer has a plurality of grooves formed in one main surface of the pair of main surfaces at intervals in the first direction, and the extraction element is The light diffusion part formed in the groove may be used.

  In the second light guide plate according to the present invention, the one main surface may be a surface facing the leading light layer side of the pair of main surfaces, or of the pair of main surfaces. The surface may face the side opposite to the leading light layer.

  In the second light guide plate according to the present invention, the extraction element may have an aspect ratio of 0.1 or more.

  A second light guide plate according to the present invention is provided on the opposite side of the extraction light guide layer from the main light layer so as to be adjacent to the extraction light guide layer and is lower in refractive index than the extraction light guide layer. A second low refractive index layer having a refractive index may be further provided.

  The second light guide plate according to the present invention further includes a cover layer disposed on a side of the second low refractive index layer opposite to the extraction light guide layer, and the second low refractive index layer includes the extraction low layer. You may make it be a layer for joining a light guide layer and the said cover layer.

  In the second light guide plate according to the present invention, the cover layer may have higher scratch resistance than the extraction light guide layer.

  In the second light guide plate according to the present invention, the extraction element is disposed adjacent to the main light layer in the second region, and a difference in refractive index between the extraction element and the main light layer is the low refractive index. The refractive index difference between the refractive index layer and the leading light layer may be smaller.

  In the second light guide plate according to the present invention, a width along the first direction may be constant among the plurality of extraction elements included in the extraction light guide layer.

  In the second light guide plate according to the present invention, a pitch along the first direction may be constant among the plurality of extraction elements included in the extraction light guide layer.

  In the second light guide plate according to the present invention, each extraction element may extend linearly in a direction non-parallel to the first direction.

  The second light guide plate according to the present invention further includes a third low refractive index layer provided on the second main surface of the main light layer and having a refractive index lower than that of the main light layer. It may be.

  The second light guide plate according to the present invention further includes a cover layer disposed on a side of the third low refractive index layer opposite to the main light layer, and the third low refractive index layer includes the extraction guide. You may make it be a layer for joining an optical layer and the said cover layer.

  In the second light guide plate according to the present invention, the cover layer may have higher scratch resistance than the main light layer.

A second lighting device according to the present invention comprises:
Any of the second light guide plates according to the invention described above;
And a light source disposed to face the light incident surface of the light guide plate.

  According to the present invention, the extraction element for extracting light from the light guide plate can be made inconspicuous.

FIG. 1 is a view for explaining an embodiment of the present invention, and is a longitudinal sectional view showing an illumination device and a light guide plate. FIG. 2 is a partial perspective view showing the lighting device and the light guide plate. FIG. 3 is a plan view showing the lighting device and the light guide plate. FIG. 4 is a partially enlarged view showing the light guide plate of FIG. FIG. 5 is a diagram corresponding to FIG. 1 and showing a modification of the light guide plate and the lighting device. FIG. 6 is a view for explaining an embodiment of the present invention, and is a longitudinal sectional view showing an illumination device and a light guide plate. FIG. 7 is a partial perspective view showing the lighting device and the light guide plate. FIG. 8 is a plan view showing the illumination device and the light guide plate. FIG. 9 is a diagram corresponding to FIG. 6 and showing a modification of the light guide plate. FIG. 10 is a view corresponding to FIG. 6 and showing another modification of the light guide plate. FIG. 11 is a partially enlarged view showing still another modification of the light guide plate in the same field of view as FIG.

  Hereinafter, first and second embodiments of the present invention will be described with reference to the drawings. 1-5 is a figure for demonstrating the 1st Embodiment of this invention and its modification. On the other hand, FIGS. 6 to 11 are diagrams for explaining the second embodiment of the present invention and its modification.

  In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product.

  In the present specification, the terms “plate”, “sheet”, and “film” are not distinguished from each other only based on the difference in names. For example, “plate” is a concept that includes members that can be referred to as sheets and films. Therefore, “light guide plate” is only different from the members that are referred to as “light guide sheet” and “light guide film”. Cannot be distinguished.

  In addition, “plate surface (sheet surface, film surface)” means a target plate-like member (sheet-like) when the target plate-like (sheet-like, film-like) member is viewed as a whole and globally. It refers to the surface that coincides with the plane direction of the member or film-like member. In the following first embodiment, the plate surface of the light guide plate, the plate surface of the extraction light guide layer of the light guide plate, and the plate surface of the base portion of the extraction light guide layer are parallel to each other. Further, in a second embodiment to be described later, the plate surface of the light guide plate, the plate surface of the main light layer of the light guide plate, the plate surface of the extraction light guide layer of the light guide plate, and the base portion of the extraction light guide layer The plate surfaces are parallel to each other.

  Furthermore, as used in this specification, the shape and geometric conditions and the degree thereof are specified. For example, terms such as “parallel”, “orthogonal”, “identical”, length and angle values, etc. Without being bound by meaning, it should be interpreted including the extent to which similar functions can be expected.

<First Embodiment>
First, the first embodiment will be described.

  1-4 is a figure for demonstrating the 1st Embodiment of this invention. Among these, FIGS. 1-3 is the longitudinal cross-sectional view which shows the illuminating device 10, respectively, a partial perspective view, and a partial top view. FIG. 4 is a partially enlarged view of FIG. Moreover, the cross section shown by FIG.1 and FIG.4 has shown the cross section along the AA of FIG.

  The illumination device 10 is a device that emits light in a planar shape, and can be used for various applications such as indoor or outdoor illumination, advertising illumination, and backlight for a display device. As shown in FIGS. 1 to 3, the lighting device 10 is configured as a so-called edge-light type lighting device, and includes a light guide plate 30 and a light source 20 including a light emitter 22 disposed on a side of the light guide plate 30. have. The light guide plate 30 is formed in a flat plate shape, and has a first main surface 31a and a second main surface 31b as a pair of opposing main surfaces. In the illustrated first embodiment, the first main surface 31 a forms the light emitting surface 10 a of the lighting device 10. The illumination device 10 includes a housing 11 provided so as to face the second main surface 31b of the light guide plate 30 as indicated by a two-dot chain line in FIG. The casing 11 covers the second main surface 31b of the light guide plate 30 so as to be connected to the entire circumference of the side end surface of the light guide plate 30 at the end thereof. The inner surface of the housing 11 is formed as a reflective surface made of a highly reflective material such as metal.

  In the illustrated example, the flat light guide plate 30 is formed in a quadrangular shape in plan view. Therefore, the first main surface 31a and the second main surface 31b, which are a pair of main surfaces, are also formed in a square shape, and four side surfaces defined between the pair of main surfaces 31a and 31b of the light guide plate 30 are four. Includes face. One side surface of the two side surfaces facing the first direction d1 extending along the plate surface of the light guide plate 30 forms a light incident surface 31c. As shown in FIGS. 1 and 2, the light emitter 22 of the light source 20 is provided facing the light incident surface 31c. As shown in FIG. 1, the light L11, L12, L13 incident on the light guide plate 30 from the light incident surface 31c is directed toward the opposite surface 31d facing the light incident surface 31c along the first direction (light guide direction) d1. In general, the light guide plate 30 travels along the first direction (light guide direction) d1.

  The light source 20 can be configured in various modes such as a fluorescent lamp such as a linear cold cathode tube, a point LED (light emitting diode), an incandescent lamp, and the like. In the first embodiment, the light source 20 includes a large number of point light emitters 22 arranged side by side along the second direction d2 that is the longitudinal direction of the light incident surface 31c, specifically, a large number of light emitting diodes. (LED). The output of each point light emitter 22, that is, the lighting and extinction of each point light emitter 22, and / or the brightness when each point light emitter 22 is turned on is independent of the output of the other point light emitters. It is preferable that it can be adjusted. In the illustrated example, the first direction d1 and the second direction d2 are orthogonal to each other and are both parallel to the plate surface of the light guide plate 30.

  Next, the light guide plate 30 will be described in more detail with reference to FIGS. The light guide plate 30 has a flat extraction light guide layer 40 including a pair of opposed main surfaces 41a and 41b. The extraction light guide layer 40 has a first main surface 41 a located on the side close to the first main surface 31 a of the light guide plate 30 and a second main surface 41 b close to the second main surface 31 b of the light guide plate 30. It is arranged to be located on the side. Further, in the illustrated example, the light guide plate 30 includes a first low refractive index layer 55 and a first cover layer 56 that are sequentially stacked on the extraction light guide layer 40 from the first main surface 41a side, and a second main surface 41b. A second low-refractive index layer 57 and a second cover layer 58, which are sequentially stacked on the extraction light guide layer 40 from the side.

  The extraction light guide layer 40 includes a base portion 45 having a first main surface 46 a and a second main surface 46 b that form a pair of opposing main surfaces, and a light diffusion portion 50 provided in the base portion 45. doing. In the illustrated example, a plurality of grooves 49 are formed in the second main surface 46b of the base portion 45 with an interval in the first direction d1. The light diffusing unit 50 is provided in the groove 49. The base portion 45 is formed as a plate-like member having a rectangular shape in plan view corresponding to the outer contour of the light guide plate 30. In the illustrated example, the light diffusing portion 50 is disposed inside the groove 49 so as to fill the corresponding groove 49 of the base portion 45. The first main surface 41 a of the extraction light guide layer 40 is formed by the first main surface 46 a of the base portion 45, and the second main surface 41 b of the extraction light guide layer 40 is the second main surface 46 b of the base portion 45. And the end face of the light diffusion portion 50.

  Four side surfaces are formed between the pair of main surfaces 46 a and 46 b of the base portion 45. Of the pair of side surfaces 46c and 46d opposed to the first direction d1, the light incident side surface 46c arranged on one side close to the light source 20 in the first direction d1 serves as the light incident surface 31c of the light guide plate 30. The opposite side surface 46d formed and disposed on the other side away from the light source 20 in the first direction d1 forms the opposite surface 31d of the light guide plate 30.

  Since the base portion 45 is a portion that guides light from the light source 20, the base portion 45 is formed of a material having high transmittance, for example, a transparent resin material. On the other hand, the light diffusing unit 50 is a layer having a function of diffusing incident light, and is a part that changes the traveling direction of light traveling through the extraction light guide layer 40. As will be described later, the light whose traveling direction is bent by the light diffusing unit 50 can be emitted from the extraction light guide layer 40. In other words, the light diffusing unit 50 functions as an extraction element for extracting light guided through the extraction light guide layer 40 of the light guide plate 30 from the light guide plate 30.

  As shown in FIG. 4, such a light diffusion portion 50 can be configured to have a main portion 50 a made of a resin material and a diffusion component 50 b dispersed in the main portion 50 a. Here, the diffusion component is a component that can exhibit a function of changing the direction of light by reflection, refraction, or the like. Examples of the diffusion component include a metal compound, a porous material containing gas, resin beads holding the metal compound around, white fine particles, and simple bubbles. An example of white particles forming the diffusing component is acrylic resin particles to which titanium oxide is added. The acrylic resin particles can be contained in the light diffusion portion at a weight percent of 20% to 30%. The average particle diameter (average diameter) of the white particles can be, for example, 1 μm or more and 30 μm or less. The cross-sectional area of the light diffusion part in the cross section perpendicular to the normal direction of the light guide plate may be larger than the square of the average particle diameter of the white particles so that the light diffusion part can contain white particles. Further, the width w along the first direction of light diffusion can be set to be equal to or greater than the average particle diameter (average diameter) so that the light diffusion portion can contain white particles.

  The illustrated light diffusion portion 50 is formed in the groove 49 of the base portion 45 and forms the extraction light guide layer 40 having a rectangular thin plate shape together with the base portion 45. Therefore, each light diffusion portion 50 is configured with a shape and an arrangement corresponding to the groove 49. For this reason, in the following, the shape and arrangement of the light diffusing unit 50 will be described as a representative, and the shape and arrangement of the groove 49 will be described.

  As shown in FIG. 1, the plurality of light diffusion portions 50 are arranged in the first direction d1. Each light diffusion portion 50 extends in a direction non-parallel to the first direction d1 that is the arrangement direction. In particular, in the illustrated example, as shown in FIG. 2, each light diffusion portion 50 extends linearly in a second direction d2 orthogonal to the first direction d1. Each light diffusion portion 50 has a rectangular shape in a cross section orthogonal to the longitudinal direction thereof, that is, a cross section orthogonal to the second direction d2. A pair of rectangular surfaces forming a cross section of the light diffusing unit 50 extends along the normal direction nd to the plate surface of the light guide plate 30.

  In the illustrated example, the height h (see FIG. 4) of the light diffusion portion 50 along the normal direction nd (see FIG. 4) to the plate surface of the light guide plate 30 is a plurality of heights included in the extraction light guide layer 40. The light diffusing unit 50 is not constant. The light diffusing unit 50 functions as an extraction element that diffuses incident light and causes emission from the light guide plate 30 as described above. Therefore, the light quantity distribution from the extraction light guide layer 40 can be adjusted by the volume distribution in the extraction light guide layer 40 of the light diffusion portion 50. For this reason, in consideration of the tendency that the amount of emitted light tends to decrease in a region separated from the light source 20 along the light guide direction d1, the height h of the light diffusing unit 50 is determined in the light guide direction. The emitted light quantity distribution in a certain first direction d1 can be controlled.

  In the illustrated example, the height h of the light diffusing unit 50 is determined as follows from the viewpoint of uniformizing the emitted light amount distribution along the first direction d1. First, the height h of at least one light diffusing unit 50 is higher than that of at least one other light diffusing unit 50 located closer to the light source 20 in the first direction d1 than the one light diffusing unit 50. It is higher than h. This makes it easy to enter the light diffusing unit 50 even in a region separated from the light source 20 along the light guide direction in which the amount of emitted light tends to decrease, and the amount of emitted light can be ensured in the region separated from the light source 20. It becomes. Further, in the illustrated example, the height of any one light diffusing unit 50 is other light diffusing unit 50 located on one side closer to the light source 20 in the first direction d1 than the one light diffusing unit 50. It is more than the height of. Alternatively, the height of any one light diffusing unit 50 is higher than the height of the other light diffusing unit 50 located on one side closer to the light source 20 in the first direction d1 than the one light diffusing unit 50. ing. According to such a distribution of the height h of the light diffusing unit 50, it is possible to easily enter the light diffusing unit 50 as the distance from the light source 20 increases, and as a result, the emitted light amount distribution along the light guide direction is effective. Can be made uniform.

  On the other hand, the width w of the light diffusion portion 50 along the first direction d1 is constant among the plurality of light diffusion portions 50 included in the extraction light guide layer 40 as in the illustrated example. Preferably it is. Similarly, the pitch of the light diffusion portions 50 along the first direction d1 is also constant among the plurality of light diffusion portions 50 included in the extraction light guide layer 40 as in the illustrated example. Is preferred. Furthermore, the separation distance d along the first direction d1 between the two light diffusion units adjacent to each other in the first direction d1 is also a plurality of light diffusion units 50 included in the extraction light guide layer 40 as in the illustrated example. It is preferable that the interval is constant. According to such a configuration, the light diffusing unit 50 that is easily distinguished from the base unit 45 because it has a different transmittance from the base unit 45 can be made inconspicuous.

  Specific dimensions of the extraction light guide layer 40 as described above can be set as follows as an example. First, the thickness along the normal direction nd to the plate surface of the extraction light guide layer 40 can be 2 mm or more and 10 mm or less. In addition, the width w of the light diffusion portion 50 along the first direction d1 can be set to 1 μm or more and 20 μm or less. Furthermore, the separation distance d along the first direction d1 between the two adjacent light diffusion portions 50 can be set to 50 μm or more and 500 μm or less. Furthermore, the height h of the light diffusion portion 50 along the normal direction nd to the plate surface of the extraction light guide layer 40 can be set to 1 μm or more and 50 μm or less. Further, the ratio (h / w) of the height h of the light diffusion portion 50 along the normal direction nd to the plate surface of the extraction light guide layer 40 with respect to the width w of the light diffusion portion 50 along the first direction d1. That is, the aspect ratio of the light diffusing portion 50 can be set to 0.1 or more and 10 or less, preferably larger than 1. When the aspect ratio of the light diffusing unit 50 is high, light is emitted in a certain volume in the light guide plate 30 while reducing the projection area of the light diffusing unit 50 along the normal direction nd to the plate surface of the light guide plate 30. The diffusion unit 50 can be included. That is, as shown in FIG. 3, when the light guide plate 30 is observed from the normal direction nd, the light diffusion portion 50 functions effectively as an extraction element while preventing the light diffusion portion 50 from conspicuous. Can be possible.

In addition, in order to realize light guide by repeating total reflection on each of the pair of main surfaces 46a and 46b of the base portion 45, any two light diffusion portions 50 adjacent in the first direction d1 are:
A separation distance d along the first direction d1 of the two light diffusion parts 50,
The heights h ₁ and h ₂ along the normal direction nd of the extraction light guide layer 40 of the light diffusion portion 50 of the two lights,
The refractive index n of the extraction light guide layer 40;
The refractive index n _L of the layer 57 adjacent to the extraction light guide layer 40 from the side of the surface 46b where the light diffusion portion 50 is provided;
The following equation (a) using is satisfied.
Arcsin (n _L / n) ≦ Arctan (d / (h ₁ + h ₂ )) Expression (a)
The total reflection critical angle θ _t at the interface between the adjacent layer (second low refractive index layer in the illustrated example) 57 and the base portion 45 is “Arcsin (n _L / n)”. When the total reflection critical angle θ _t becomes larger than the angle θ _a (= Arctan (d / (h ₁ + h ₂ )) in FIG. 4, the distance between the two light diffusion portions 50 shown in FIG. in a position, the light totally reflected at the second main surface 46b of the base portion 45 is always incident to the light diffusing portion 50 of a height h ₂ which is located on the other side, the light of within the base portion 45 It will not be possible to continue. Therefore, any two light diffusion portions 50 adjacent in the first direction d1 satisfy the formula (a). Preferably, any two light diffusion units 50 adjacent in the first direction d1 all satisfy the formula (a).

  As one specific example, the extraction light guide layer 40 having the above-described configuration can be manufactured as follows. First, the base portion 45 is manufactured using, for example, a curable material such as epoxy acrylate having a characteristic of being cured by irradiation with ionizing radiation such as an electron beam or ultraviolet rays. Next, an uncured and liquid composition containing a curable material that becomes a main part of the light diffusion unit 50 by curing and a diffusion component of the light diffusion unit 50 is used to form the light diffusion unit. 50 is produced. A curable material such as urethane acrylate having a characteristic of being cured by ionizing radiation can be used as the curable material that becomes the main part of the light diffusion portion 50 by being cured. First, a composition is supplied on the base part 45 formed previously. Thereafter, the composition inside the groove 49 of the base portion 45 is filled with the composition using a doctor blade, and the excess composition overflowing outside the groove 49 is scraped off. In order to avoid the diffusion component remaining on the main surface of the base portion 45 due to the fact that it cannot be scraped off, the particle size of the diffusion component is preferably 1 μm or more, and the width of the groove 49 It is preferably 50% or less. Then, the light diffusion part 50 is formed by irradiating the composition in the groove 49 with ionizing radiation and curing it. Thereby, the extraction light guide layer 40 having the base portion 45 and the light diffusion portion 50 is produced.

  Next, the other layers 55, 56, 57, and 58 included in the light guide plate 30 will be described. First, the first low refractive index layer 55 and the second low refractive index layer 57 disposed adjacent to the main surface of the extraction light guide layer 40 have a refractive index lower than that of the base portion 45 of the extraction light guide layer 40. Layer. In the light guide plate 30 described here, light is guided by reflection at the interface between the base portion 45 of the extraction light guide layer 40 and the low refractive index layers 55 and 57, particularly total reflection due to the difference in refractive index. Expecting. For this reason, it is preferable that the refractive index of the low refractive index layers 55 and 57 is 0.03 or more lower than the refractive index of the base part 45 of the extraction light guide layer 40, and is 0.06 or less. It is more preferable. In the illustrated example, the low refractive index layers 55 and 57 are formed as bonding layers made of an adhesive, an adhesive, or the like, and the cover layers 56 and 58 are taken out and bonded to the light guide layer 40. Functions as a layer.

  On the other hand, the first cover layer 56 and the second cover layer 58 are layers that define a pair of main surfaces 31 a and 31 b of the light guide plate 30. Such cover layers 56 and 58 can be formed as, for example, a hard coat layer having better scratch resistance than the extraction light guide layer 40 and the low refractive index layers 55 and 57. In addition, the scratch resistance mentioned in this specification is evaluated based on the test result in the pencil hardness test implemented based on JISK5600-5-4 (1999).

  Next, the operation of the illumination device 10 and the light guide plate 30 having the above-described configuration will be described.

  First, as shown in FIG. 1, the light emitted from the light emitter 22 that constitutes the light source 20 enters the extraction light guide layer 40 of the light guide plate 30 through the light incident surface 31 c. Due to the fact that the refractive index of the material forming the extraction light guide layer 40 is normally 1.4 to 1.6, the extraction light guide layer 40 has a refractive index of 1 from the air layer as shown in FIG. The traveling directions of the lights L11, L12, and L13 incident on the base portion 45 are normal to the light incident side surface 46c of the base portion 45 (the light incident surface 31c of the light guide plate 30), that is, the first direction d1. There is no significant inclination. And most of the light L11, L12, L13 incident on the base portion 45 of the extraction light guide layer 40 is reflected on the first main surface 46a and the second main surface 46b of the base portion 45, in particular, the base portion 45 and the base portion. 45 repeats total reflection caused by the difference in refractive index between the low refractive index layers 55 and 57 adjacent to 45 and guides the light incident side surface 46c of the base portion 45 to the opposite side surface 46d. Proceed in one direction d1.

  However, the light diffusion part 50 is provided in the extraction light guide layer 40 with an interval in the first direction d1. The light diffusion part 50 is formed in the groove 49 of the base part 45 and extends into the extraction light guide layer 40 from the second main surface 41b of the extraction light guide layer 40 along the normal direction nd of the extraction light guide layer 40. I'm out. Therefore, the light traveling in the base portion 45 of the extraction light guide layer 40 may enter the light diffusion portion 50. As shown in FIG. 1, when the light traveling in the base portion 45 enters the light diffusion portion 50, the traveling direction is bent by the diffusion function of the light diffusion portion 50.

  As a result, the light diffused by the light diffusing unit 50 is incident on the first main surface 41a of the extraction light guide layer 40 at an angle equal to or less than the total reflection critical angle, and the extraction light guide layer 40 is interposed via the first main surface 41a. It comes out from. Such light passes through the first low-refractive index layer 55 and the first cover layer 56 and is emitted as illumination light from the light guide plate 30 through the first main surface 31a forming the light emitting surface 10a. At this time, although light traveling toward the second main surface 31b of the light guide plate 30 is also generated by diffusion in the light diffusion unit 50, such light is reflected by the inner surface of the housing 11 and reenters the light guide plate 30. Thereafter, the light is emitted from the light guide plate 30 as illumination light or guided through the light guide plate 30.

  In addition, the light-diffusion part 50 is arranged in the 1st direction which is a light guide direction. Therefore, the light traveling in the base portion 45 of the extraction light guide layer 40 enters the light diffusion portion 50 in each section along the light guide direction. For this reason, the light traveling in the base portion 45 of the extraction light guide layer 40 comes out from the light guide plate 30 in each section along the light guide direction. In particular, when the height h of the light diffusing unit 50 is adjusted as described above, the amount of emitted light on the side close to the light source increases along the light guide direction and is separated from the light source along the light guide direction. The tendency that the amount of emitted light on the side to be reduced is effectively eliminated, and the distribution of the amount of emitted light from each position along the light guide direction can be effectively made uniform. More specifically, the height h of at least one light diffusing unit 50 is greater than the height of at least one other light diffusing unit 50 located on the light source side in the first direction d1 relative to the one light diffusing unit 50. Is higher, more preferably, the height h of any one light diffusing unit 50 is higher than the other light diffusing unit 50 located on the light source side in the first direction d1 relative to the one light diffusing unit 50. When the height is greater than or equal to h or higher than the height h of the other light diffusing unit 50, the distribution of the emitted light quantity from each position along the light guide direction can be effectively made uniform.

  As described above, when light is emitted from the light guide plate 30, the light emitting surface 10a of the illumination device 10 emits illumination light.

  By the way, in the conventional light guide plate, the emitted light quantity is controlled by changing the density of the diffusible substance provided on the back surface along the light guide direction. Therefore, in the conventional light guide plate, the diffusive substance is provided on the back surface of the light guide plate with a pattern. Then, by visually recognizing the pattern of the diffusive substance, the range of use of the conventional lighting device has been limited due to problems in appearance such as deterioration in designability and loss of luxury. In addition, only the overall distribution of the emitted light quantity can be controlled only by changing the area of the diffuse reflection pattern, and it has been impossible to realize free emitted light quantity control.

  On the other hand, in the illumination device 10 and the light guide plate 30 according to the first embodiment, such a conventional problem can be solved. First, in the illuminating device 10 and the light guide plate 30 according to the first embodiment, by adjusting the height h of the light diffusing unit 50 serving as the light extraction element of the light guide plate 30, the amount of light emitted from the light guide plate 30 is guided. The distribution along the light direction (first direction) d1 is controlled. When the light guide plate 30 is observed from the normal direction nd, a change in the height h between the light diffusion portions 50 is hardly detected.

  In the light guide plate 30 according to the first embodiment, the width w of the light diffusing unit 50 along the first direction d1 and the separation distance d between the two light diffusing units 50 adjacent to each other in the first direction d1 are emitted. It does not have to be used for controlling the light quantity distribution. Therefore, the width w of the light diffusing unit 50 along the first direction d1 and the spacing d between the two light diffusing units 50 adjacent to each other in the first direction d1 can be made constant in the light guide plate 30. is there. In this case, as shown in FIG. 3, the projected area of the light diffusing unit 50 along the normal direction nd of the light guide plate 30 is the same, and the difference in configuration among the plurality of light diffusing units 50 is almost sensed. I can't.

  In addition, if the width w of the light diffusing unit 50 along the first direction d1 is sufficiently small, the presence of the light diffusing unit 50 can be hardly detected. Specifically, the haze value of the light guide plate 30 is preferably 0.1% or more and 10% or less. The haze value can be measured by a method based on JIS K7136 using a haze meter (manufactured by Murakami Color Research Laboratory, product number: HM-150).

  Furthermore, since the height h can be changed greatly between two adjacent light diffusion parts 50, the distribution of the emitted light quantity along the light guide direction can be controlled with a very high degree of freedom. it can.

  According to the first embodiment as described above, the light diffusing unit 50 that functions as an extraction element for extracting light from the light guide plate 30 can be effectively made inconspicuous. It can be effectively avoided that the design of the lighting device 10 is impaired by sensing the extraction element for extracting light from the light guide plate 30. Thereby, it becomes possible to provide the lighting device 10 with excellent design, and the lighting device 10 can be harmonized with respect to various installation positions.

  Further, according to the first embodiment, the low refractive index layers 55 and 57 are provided adjacent to the extraction light guide layer 40. An interface that reflects light traveling through the base portion 45 of the extraction light guide layer 40 is formed between the base portion 45 and the low refractive index layers 55 and 57. That is, the interface where light traveling through the base portion 45 of the extraction light guide layer 40 is reflected is not exposed. For this reason, it is possible to effectively prevent damage to the interface and adhesion of foreign substances on which light traveling through the base portion 45 of the extraction light guide layer 40 is expected to be reflected. Thereby, it can prevent effectively that the reflection of the light for the light guide in the light-guide plate 30 is inhibited. Furthermore, in the first embodiment, the surface of the light guide plate 30 is formed by the cover layers 56 and 58 that have better scratch resistance than the base portion 45 and the low refractive index layers 55 and 57. Accordingly, it is possible to more effectively prevent damage to the interface and adhesion of foreign substances on which light traveling through the light guide plate 30 is expected to be reflected.

  Various modifications can be made to the above-described first embodiment. Hereinafter, an example of modification will be described with reference to the drawings as appropriate. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above embodiment are used for the parts that can be configured in the same manner as in the above embodiment. A duplicate description is omitted.

  In the first embodiment described above, an example in which the groove 49 is formed on the second main surface 46 b of the base portion 45 and the light diffusion portion 50 is provided on the second main surface 41 b of the extraction light guide layer 40. Although shown, it is not limited to this. A groove 49 may be formed in the first main surface 46 a of the base portion 45, and the light diffusion portion 50 may be disposed on the first main surface 41 a of the extraction light guide layer 40. Further, a groove 49 is formed in each of the first main surface 46a and the second main surface 46b of the base portion 45, and light diffusion is performed on both the first main surface 41a and the second main surface 41b of the extraction light guide layer 40. The part 50 may be arranged.

  In the first embodiment described above, the light guide plate 30 includes the first low refractive index layer 55, the first cover layer 56, the second low refractive index layer 57, and the second cover layer 58. . In such an example, in order to promote extraction of light from the light guide plate 30, it is preferable that at least one of the first low refractive index layer 55 and the first cover layer 56 contains a diffusing component. In order to promote the extraction of light from the light guide plate 30, it is preferable that at least one of the second low refractive index layer 57 and the second cover layer 58 contains a diffusing component. On the other hand, the first low refractive index layer 55, the first cover layer 56, the second low refractive index layer 57, and the second cover layer 58 are not essential, and one or more of them can be omitted from the light guide plate 30.

  Furthermore, in the first embodiment described above, an example in which the second main surface 31b of the light guide plate 30 is covered by the housing 11 and the light emitting surface 10a is formed only on the first main surface 31a side of the light guide plate 30. Although shown, it is not limited to this. As shown in FIG. 5, a light emitting surface may be formed also on the second main surface 31 b side of the light guide plate 30. That is, the illumination device 10 may have a pair of light emitting surfaces facing each other.

  Furthermore, in the above-described first embodiment, the example in which the first main surface 31a of the light guide plate 30 forms the light emitting surface 10a of the lighting device 10 has been described, but the present invention is not limited thereto. Deflection means for deflecting the traveling direction of the light emitted from the light guide plate 30 is provided at a position facing the first main surface 31a of the light guide plate 30, and the light emitting surface 10a of the illumination device 10 is formed by this deflection means. You may make it do. Examples of the deflecting unit include a light collecting sheet having a prism surface or a lens surface formed on the light output side.

  In addition, although the some modification with respect to 1st Embodiment mentioned above was demonstrated above, naturally, it is also possible to apply combining several modifications suitably.

  Next, a second embodiment will be described. The light guide plate 30 described below is configured to extract light from only a partial region of the main surface of the light guide plate. In the second embodiment described below, the light guide plate 30 is a first low-refractive index layer in which the main light layer 70 is arranged by patterning between the main light layer 70 and the extraction light guide layer 40. 61 in that the first embodiment is different from the first embodiment described above. In the description of the second embodiment below, the same reference numerals are assigned to the corresponding parts in the first embodiment, and overlapping descriptions are omitted as much as possible.

  6-8 is a figure for demonstrating the 2nd Embodiment of this invention. Among these, FIGS. 6-8 is the longitudinal cross-sectional view which shows the illuminating device 10, respectively, a partial perspective view, and a top view. The cross section shown in FIG. 6 shows a cross section along the line AA in FIG.

  The illumination device 10 is a device in which a part of the outermost surface 10a emits light in a planar shape, and can be used for various applications such as indoor or outdoor illumination, advertising illumination, and backlight for a display device. . As shown in FIGS. 6-8, the illuminating device 10 is comprised as what is called an edge light type illuminating device, and the light source 20 including the light-guide plate 30 and the light-emitting body 22 arrange | positioned at the side of the light-guide plate 30, have. The light guide plate 30 is formed in a flat plate shape, and has a first main surface 31a and a second main surface 31b as a pair of opposing main surfaces. In the illustrated second embodiment, the first main surface 31 a forms the outermost surface 10 a of the lighting device 10. The illumination device 10 includes a housing 11 provided so as to face the second main surface 31b of the light guide plate 30, as indicated by a two-dot chain line in FIG. The casing 11 covers the second main surface 31b of the light guide plate 30 so as to be connected to the entire circumference of the side end surface of the light guide plate 30 at the end thereof. The inner surface of the housing 11 is formed as a reflective surface made of a highly reflective material such as metal.

  In the illustrated example, the flat light guide plate 30 is formed in a quadrangular shape in plan view. Therefore, the first main surface 31a and the second main surface 31b, which are a pair of main surfaces, are also formed in a square shape, and four side surfaces defined between the pair of main surfaces 31a and 31b of the light guide plate 30 are four. Includes face. One side surface of the two side surfaces facing the first direction d1 extending along the plate surface of the light guide plate 30 forms a light incident surface 31c. As shown in FIGS. 6 and 7, the light emitter 22 of the light source 20 is provided facing the light incident surface 31c. As shown in FIG. 6, the light L61 and L62 incident on the light guide plate 30 from the light incident surface 31c is substantially directed toward the opposite surface 31d facing the light incident surface 31c along the first direction (light guide direction) d1. The light guide plate 30 travels along the first direction (light guide direction) d1.

  The light source 20 can be configured the same as in the first embodiment described above. In the illustrated second embodiment, the light source 20 includes a large number of point light emitters 22 arranged side by side along the second direction d2 that is the longitudinal direction of the light incident surface 31c, specifically, a large number. The light emitting diode (LED) is used. In the illustrated example, the first direction d1 and the second direction d2 are orthogonal to each other and are both parallel to the plate surface of the light guide plate 30.

  Next, the light guide plate 30 will be described in more detail with reference to FIGS. The light guide plate 30 includes a flat main light layer 70 including a pair of opposing first main surface 71a and second main surface 71b, and a first low refraction provided on the first main surface 71a of the main light layer 70. An index layer (patterning low-refractive index layer) 61 and an extraction light guide layer 40 laminated with the main light layer 70 from the first low-refractive index layer 61 side are provided. As well shown in FIG. 8, the first main surface 71a of the main light layer 70 includes a first region Z1 and a second region Z2. As described above, the outermost surface 10a of the lighting device 10 described here emits light in a partial region thereof. The first region Z1 faces a region that does not emit light, and the second region Z2 faces a region that emits light. The first low refractive index layer 61 is provided only on the first region Z1 on the first main surface 71a, and is not provided on the second region Z2. As shown in FIGS. 6 and 7, in the illustrated example, the light guide plate 30 is a second low refractive index layer (front side) laminated in order on the side opposite to the main light layer 70 of the extraction light guide layer 40. A third low-refractive-index layer (back-side low-refractive-index layer) sequentially laminated on the side opposite to the extraction light-guiding layer 40 of the main light layer 70 and the first cover layer (front-side cover layer) 66; ) 63 and a second cover layer (back side cover layer) 67. Hereinafter, each layer will be described.

  First, the main light layer 70 will be described. The main light guide layer 70 has a first main surface 71 a located on the side close to the first main surface 31 a of the light guide plate 30 and a second main surface 71 b on the side close to the second main surface 31 b of the light guide plate 30. It is arranged to be located in. The main light guide layer 70 is formed as a plate-like member having a rectangular shape in plan view corresponding to the outer contour of the light guide plate 30. Four side surfaces are formed between the pair of main surfaces 71 a and 71 b of the main light guide layer 70. Of the pair of side surfaces 71c and 71d opposed to the first direction d1, the light incident side surface 71c arranged on one side close to the light source 20 in the first direction d1 serves as the light incident surface 31c of the light guide plate 30. The opposite side surface 71d formed and disposed on the other side away from the light source 20 in the first direction d1 forms the opposite surface 31d of the light guide plate 30. That is, as shown in FIG. 7, the light emitter 22 of the light source 20 is disposed to face the side surface of the main light layer 70. Since the main light guide layer 70 is a part that guides light from the light source 20, the main light guide layer 70 is formed of a material having high transmittance, for example, a transparent resin material.

  As shown in FIG. 8, the first region Z1 and the second region Z2 are partitioned along the first direction d1 on the first main surface 71a of the main light layer 70. In the illustrated example, the second region Z2 is disposed at the center in the first direction d1, and the first region Z1 is provided on both outer sides of the second region Z2 in the first direction d1. However, the ranges of the first region Z1 and the second region Z2 are determined corresponding to the portion of the outermost surface 10a of the illumination device 10 that is desired to be illuminated. Therefore, the scope of the first region Z1 and the second region Z2 is not limited to the illustrated example, and can be arranged in various modes. For example, the first region Z1 and the second region Z2 may be partitioned along the second direction d2 on the first main surface 71a of the main light layer 70, or the first direction d1 and the second direction d2. It may be divided along both. Furthermore, the first direction d1 and the second direction d2 may be partitioned so as to form a predetermined pattern.

  Next, the first low refractive index layer 61 will be described. The first low refractive index layer 61 is disposed adjacent to the main light layer 70 in the first region Z1, and forms an interface with the main light layer 70. The first low refractive index layer 61 is a layer having a refractive index lower than that of the main light layer 70. In the main light layer 70 of the light guide plate 30 described here, light is guided by reflection at the interface between the main light layer 70 and the first low refractive index layer 61, particularly total reflection due to the difference in refractive index. Expecting. For this reason, the refractive index of the first low refractive index layer 61 is preferably 0.03 or more lower than the refractive index of the main light layer 70, and more preferably 0.06 or lower. The first low refractive index layer 61 may be a bonding layer (for example, an adhesive layer or an adhesive layer) for bonding the main light layer 70 and the extraction light guide layer 40.

  Next, the extraction light guide layer 40 will be described. The extraction light guide layer 40 has a plurality of extraction elements 53 arranged in the first direction d1. The extraction element 53 changes the traveling direction of light from the main light layer 70. As will be described later, the light whose traveling direction is bent by the extraction element 53 can be emitted from the light guide plate 30. That is, the extraction element 53 functions as an element for extracting light guided through the light guide plate 30 from the light guide plate 30. However, the extraction element 53 is disposed not only in the area facing the second area Z2 corresponding to the light emitting area, but also in the area facing the first area Z1b corresponding to the area not emitting light. Hereinafter, an example of the extraction light guide layer 40 shown in FIGS. 6 to 8 will be described in detail. The take-out light guide layer 40 of the second embodiment shown in FIGS. 6 to 10 can be configured similarly to the take-out light guide layer of the first embodiment described above.

  6 to 8, the extraction light guide layer 40 is formed in a flat plate shape including a pair of opposed main surfaces 41a and 41b. The extraction light guide layer 40 has a first main surface 41 a located on the side close to the first main surface 31 a of the light guide plate 30 and a second main surface 41 b of the second main surface 31 b of the light guide plate 30. It arrange | positions so that it may be located in the adjacent side. In the illustrated example, the extraction light guide layer 40 is located closer to the first main surface 31a of the light guide plate 30 that forms the outermost surface 10a of the illumination device 10 than the main light layer 70.

  The extraction light guide layer 40 includes a base portion 45 having a first main surface 46 a and a second main surface 46 b that form a pair of opposing main surfaces, and a light diffusion portion 50 provided in the base portion 45. doing. In the illustrated example, a plurality of grooves 49 are formed in the second main surface 46b of the base portion 45 with an interval in the first direction d1. The light diffusing unit 50 is provided in the groove 49. The base portion 45 is formed as a plate-like member having a rectangular shape in plan view corresponding to the outer contour of the light guide plate 30. In the illustrated example, the light diffusing portion 50 is disposed inside the groove 49 so as to fill the corresponding groove 49 of the base portion 45. The first main surface 41 a of the extraction light guide layer 40 is formed by the first main surface 46 a of the base portion 45, and the second main surface 41 b of the extraction light guide layer 40 is the second main surface 46 b of the base portion 45. And the end face of the light diffusion portion 50.

  Four side surfaces are formed between the pair of main surfaces 46 a and 46 b of the base portion 45. Of the pair of side surfaces 46c and 46d facing the first direction d1, the light incident side surface 46c arranged on one side close to the light source 20 in the first direction d1 is the light incident surface 31c of the light guide plate 30. The opposite side surface 46d that forms a part and is disposed on the other side that is separated from the light source 20 in the first direction d1 forms a part of the opposite surface 31d of the light guide plate 30. However, the light emitter 22 of the light source 20 is not disposed at a position facing the light incident side surface 46 c of the base portion 45.

  As will be described later, the base portion 45 guides light from the light source 20 at least in a region facing the second region Z2. Therefore, the base portion 45 is formed of a material having a high transmittance, for example, a transparent resin material. On the other hand, the light diffusion portion 50 is a layer having a function of diffusing incident light. In the example shown in FIGS. 6 to 8, the light diffusing portion 50 forms the extraction element 53 that changes the traveling direction of the light traveling in the extraction light guide layer 40. Therefore, the light diffusion part 50 is provided in a region facing both the first region Z1 and the second region Z2. Similar to the first embodiment described above, the light diffusing unit 50 includes a main part 50a (see FIG. 4) made of a resin material and a diffusion component 50b dispersed in the main part (see FIG. 4). And can be configured to have.

  Here, the diffusion component is a component that can exhibit a function of changing the direction of light by reflection, refraction, or the like. Examples of the diffusion component include a metal compound, a porous material containing gas, resin beads holding the metal compound around, white fine particles, and simple bubbles. An example of white particles forming the diffusing component is acrylic resin particles to which titanium oxide is added. The acrylic resin particles can be contained in the light diffusion portion at a weight percent of 20% to 30%. The average particle diameter (average diameter) of the white particles can be, for example, 1 μm or more and 30 μm or less. The cross-sectional area of the light diffusion part in the cross section perpendicular to the normal direction of the light guide plate may be larger than the square of the average particle diameter of the white particles so that the light diffusion part can contain white particles. Further, the width w along the first direction of light diffusion can be set to be equal to or greater than the average particle diameter (average diameter) so that the light diffusion portion can contain white particles.

  The illustrated light diffusion portion 50 is formed in the groove 49 of the base portion 45 and forms the extraction light guide layer 40 having a rectangular thin plate shape together with the base portion 45. Therefore, each light diffusion portion 50 is configured with a shape and an arrangement corresponding to the groove 49. For this reason, in the following, the shape and arrangement of the light diffusing unit 50 will be described as a representative, and the shape and arrangement of the groove 49 will be described.

  As shown in FIG. 6, the plurality of light diffusion portions 50 are arranged in the first direction d1. Each light diffusion portion 50 extends in a direction non-parallel to the first direction d1 that is the arrangement direction. In particular, in the illustrated example, as shown in FIG. 7, each light diffusion portion 50 extends linearly in a second direction d2 orthogonal to the first direction d1. Each light diffusion portion 50 has a rectangular shape in a cross section orthogonal to the longitudinal direction thereof, that is, a cross section orthogonal to the second direction d2. A pair of rectangular surfaces forming a cross section of the light diffusing unit 50 extends along the normal direction nd to the plate surface of the light guide plate 30.

  In the illustrated example, the height h (see FIG. 6) of the light diffusion portion 50 along the normal direction nd to the plate surface of the light guide plate 30 is the plurality of light diffusion portions 50 included in the extraction light guide layer 40. Is not constant. The light diffusing unit 50 functions as an extraction element that diffuses incident light and causes emission from the light guide plate 30 as described above. Therefore, the light quantity distribution from the extraction light guide layer 40 can be adjusted by the volume distribution in the extraction light guide layer 40 of the light diffusion portion 50. For this reason, in consideration of the tendency that the amount of emitted light tends to decrease in a region separated from the light source 20 along the light guide direction d1, the height h of the light diffusing unit 50 is determined in the light guide direction. The emitted light quantity distribution in a certain first direction d1 can be controlled.

  In the illustrated example, the height h of the light diffusing unit 50 is determined as follows from the viewpoint of uniformizing the emitted light amount distribution along the first direction d1. First, the height h of at least one light diffusing unit 50 is higher than that of at least one other light diffusing unit 50 located closer to the light source 20 in the first direction d1 than the one light diffusing unit 50. It is higher than h. This makes it easy to enter the light diffusing unit 50 even in a region separated from the light source 20 along the light guide direction in which the amount of emitted light tends to decrease, and the amount of emitted light can be ensured in the region separated from the light source 20. It becomes. Further, in the illustrated example, the height of any one light diffusing unit 50 is other light diffusing unit 50 located on one side closer to the light source 20 in the first direction d1 than the one light diffusing unit 50. It is more than the height of. Alternatively, the height of any one light diffusing unit 50 is higher than the height of the other light diffusing unit 50 located on one side closer to the light source 20 in the first direction d1 than the one light diffusing unit 50. ing. According to such a distribution of the height h of the light diffusing unit 50, it is possible to easily enter the light diffusing unit 50 as the distance from the light source 20 increases, and as a result, the emitted light amount distribution along the light guide direction is effective. Can be made uniform.

On the other hand, the width w of the light diffusion portion 50 along the first direction d1 is constant among the plurality of light diffusion portions 50 included in the extraction light guide layer 40 as in the illustrated example. Preferably it is.
Similarly, the pitch of the light diffusion portions 50 along the first direction d1 is also constant among the plurality of light diffusion portions 50 included in the extraction light guide layer 40 as in the illustrated example. Is preferred. Furthermore, the separation distance d along the first direction d1 between the two light diffusion units adjacent to each other in the first direction d1 is also a plurality of light diffusion units 50 included in the extraction light guide layer 40 as in the illustrated example. It is preferable that the interval is constant. According to such a configuration, the light diffusing unit 50 that is easily distinguished from the base unit 45 because it has a different transmittance from the base unit 45 can be made inconspicuous.

  The specific dimensions of the extraction light guide layer 40 as described above can be set in the same manner as in the first embodiment described above.

  The extraction light guide layer 40 having the above-described configuration can be manufactured in the same manner as the extraction light guide layer 40 manufacturing method described in the first embodiment.

  Next, the other layers 62, 63, 66, and 67 included in the light guide plate 30 will be described. First, the second low refractive index layer 62 disposed adjacent to the first main surface 41a of the extraction light guide layer 40 and the third low refractive index disposed adjacent to the second main surface 71b of the main light layer 70. The layer 63 is a layer having a lower refractive index than that of the base portion 45 or the main light layer 70 of the extraction light guide layer 40 adjacent thereto. In the light guide plate 30 described here, the reflection at the interface between the base portion 45 and the main light layer 70 of the extraction light guide layer 40 and the second and third low refractive index layers 62 and 63, particularly due to the difference in refractive index. It is expected to guide light by total reflection. For this reason, the refractive index of the second low refractive index layer 62 is preferably 0.03 or more lower than the refractive index of the base portion 45 of the extraction light guide layer 40, and is 0.06 or lower. It is more preferable. The refractive index of the third low refractive index layer 63 is preferably 0.03 or more lower than the refractive index of the main light layer 70, and more preferably 0.06 or lower. In the illustrated example, the second and third low refractive index layers 62 and 63 are formed as bonding layers made of an adhesive, an adhesive, or the like, and the cover layers 66 and 67 are taken out. It functions as a layer for bonding to the main light guide layer 70.

  On the other hand, the first cover layer 66 and the second cover layer 67 are layers that define a pair of main surfaces 31 a and 31 b of the light guide plate 30. Such cover layers 66 and 67 can be formed, for example, as a hard coat layer having better scratch resistance than the extraction light guide layer 40, the leading light layer 70, and the low refractive index layers 61, 62 and 63. In addition, the scratch resistance mentioned in this specification is evaluated based on the test result in the pencil hardness test implemented based on JISK5600-5-4 (1999).

  Next, the operation of the illumination device 10 and the light guide plate 30 having the above-described configuration will be described.

  First, as shown in FIG. 6, the light emitted from the light emitting body 22 constituting the light source 20 enters the main light layer 70 of the light guide plate 30 through the light incident surface 31 c. Due to the fact that the refractive index of the material constituting the main light guide layer 70 is normally 1.4 to 1.6, the light enters the main light layer 70 from the air layer having a refractive index of 1, as shown in FIG. The traveling directions of the light beams L61 and L62 are greatly inclined with respect to the normal direction to the light incident side surface 71c (light incident surface 31c of the light guide plate 30) of the main light layer 70, that is, the first direction d1. There is no. And most of the lights L61 and L62 incident on the main light layer 70 are reflected on the first main surface 71a and the second main surface 71b of the main light layer 70, particularly adjacent to the main light layer 70 and the main light layer 70. The total light reflection caused by the difference in refractive index between the first and third low-refractive index layers 61 and 63 is repeated, and the light guide direction connecting the light incident side surface 71c and the opposite side surface 71d of the main light layer 70, particularly the illustrated example. Now proceed in the first direction d1. That is, in the area facing the first region Z1 where the first low-refractive index layer 61 is provided, the light from the light source 20 travels through the leading light layer 70 of the light guide plate 30, and actively from the light guide plate 30. It will not be taken out.

  Most of the lights L61 and L62 that have traveled to the area facing the second region Z2 are next on the second main surface 71b of the main light layer 70 and the first main surface 46a of the base portion 45 of the extraction light guide layer 40. Reflection, particularly the refractive index difference between the main light layer 70 and the third low refractive index layer 63 adjacent to the main light layer 70 and the refractive index difference between the base portion 45 of the extraction light guide layer 40 and the second low refractive index layer 62. Repeated total reflection caused by. Due to this reflection, light is continuously guided through the light guide plate 30 in the light guide direction connecting the light incident surface 31c and the opposite surface 31d of the light guide plate 30, particularly in the first direction d1 in the illustrated example.

  However, the light diffusion part 50 is provided in the extraction light guide layer 40 with an interval in the first direction d1. The light diffusion part 50 is formed in the groove 49 of the base part 45 and extends into the extraction light guide layer 40 from the second main surface 41b of the extraction light guide layer 40 along the normal direction nd of the extraction light guide layer 40. I'm out. Therefore, the light traveling in the base portion 45 of the extraction light guide layer 40 may enter the light diffusion portion 50. As shown in FIG. 6, when the light traveling in the base portion 45 enters the light diffusion portion 50, the traveling direction is bent by the diffusion function in the light diffusion portion 50.

  As a result, the light diffused by the light diffusing unit 50 is incident on the first main surface 41a of the extraction light guide layer 40 at an angle equal to or less than the total reflection critical angle, and the extraction light guide layer 40 is interposed via the first main surface 41a. It comes out from. Such light passes through the second low refractive index layer 62 and the first cover layer 66, and is emitted from the light guide plate 30 as illumination light through the first main surface 31a forming the outermost surface 10a of the illumination device 10. . At this time, light traveling toward the second main surface 31b of the light guide plate 30 is also generated by diffusion in the light diffusion unit 50, but such light is reflected by the inner surface of the housing 11 and reenters the light guide plate 30. Then, the light is emitted from the light guide plate 30 as illumination light or guided through the light guide plate 30.

  The light diffusing units 50 are arranged in the first direction d1 that is the light guide direction. Therefore, the light traveling in the area facing the second region Z2 in the light guide plate 30 can enter the light diffusion unit 50 in each region along the light guide direction. For this reason, the light traveling in the base portion 45 of the extraction light guide layer 40 is emitted from the light guide plate 30 in each region along the light guide direction. In particular, when the height h of the light diffusing unit 50 is adjusted as described above, the amount of emitted light on the side close to the light source 20 along the light guide direction increases and from the light source along the light guide direction. It is possible to effectively eliminate the tendency that the amount of emitted light on the side to be separated is reduced, and to effectively uniformize the distribution of the amount of emitted light from each region along the light guide direction. More specifically, the height h of at least one light diffusing unit 50 is greater than the height of at least one other light diffusing unit 50 located on the light source side in the first direction d1 relative to the one light diffusing unit 50. Is higher, more preferably, the height h of any one light diffusing unit 50 is higher than the other light diffusing unit 50 located on the light source side in the first direction d1 relative to the one light diffusing unit 50. When the height is greater than or equal to h or higher than the height h of the other light diffusing unit 50, the distribution of the emitted light quantity from each position along the light guide direction can be effectively made uniform.

  As described above, the light is emitted from the area facing the second region Z2 in which the first low refractive index layer 61 of the light guide plate 30 is not provided, and thus, of the outermost surface 10a of the illumination device 10. The area facing the second region Z2 emits illumination light. On the other hand, in the area facing the first region Z1 where the first low refractive index layer 61 of the light guide plate 30 is provided, the extraction light guide layer 40 having the light diffusion portion 50 as the extraction element 53 is provided. No light is incident. For this reason, the area facing the first region Z1 in the outermost surface 10a of the lighting device 10 does not emit light with at least sufficient brightness.

  As described above, in the conventional light guide plate, the amount of emitted light is controlled by changing the density of the diffusible substance provided on the back surface along the light guide direction. Therefore, in the conventional light guide plate, the diffusive substance is provided on the back surface of the light guide plate with a pattern. Then, by visually recognizing the pattern of the diffusive substance, the range of use of the conventional lighting device has been limited due to problems in appearance such as deterioration in designability and loss of luxury. In addition, only the overall distribution of the emitted light quantity can be controlled only by changing the area of the diffuse reflection pattern, and it has been impossible to realize free emitted light quantity control.

  On the other hand, in the illuminating device 10 and the light guide plate 30 according to the second embodiment, such a conventional problem can be solved. First, in the illumination device 10 and the light guide plate 30 according to the second embodiment, the amount of light emitted from the light guide plate 30 is adjusted by adjusting the height h of the light diffusion portion 50 that forms the light extraction element 53 of the light guide plate 30. The distribution along the light guide direction (first direction) d1 is controlled. When the light guide plate 30 is observed from the normal direction nd, a change in the height h between the light diffusing portions 50 forming the extraction element 53 is not easily detected.

  Further, in the light guide plate 30 of the second embodiment, the width w of the light diffusing unit 50 forming the extraction element 53 along the first direction d1 and the separation between the two light diffusing units 50 adjacent to each other in the first direction d1. The interval d may not be used for controlling the emitted light quantity distribution. For this reason, the width w along the first direction d1 of the light diffusing unit 50 forming the extraction element 53 and the spacing d between the two light diffusing units 50 adjacent to each other in the first direction d1 are made constant in the light guide plate 30. It is also possible to do. In this case, as shown in FIG. 8, the projected area of the light diffusing unit 50 that forms the extraction element 53 along the normal direction nd of the light guide plate 30 is the same, and the configuration difference among the plurality of light diffusing units 50 Is almost undetectable.

  In particular, in the second embodiment, not only the second region Z2 facing the light emitting portion of the outermost surface 10a but also the first region Z1 facing the non-light emitting portion of the outermost surface 10a is the extraction element. 53 is arranged. For this reason, when the outermost surface 10a is observed, it is possible to prevent the presence of the extraction element 53 from being recognized more significantly by the presence or absence of the extraction element 53, and to effectively make the extraction element 53 inconspicuous.

  In addition, if the width w along the first direction d1 of the light diffusing unit 50 forming the light diffusing unit 50 is sufficiently small, the presence of the light diffusing unit 50 can be hardly detected. Specifically, the haze value of the light guide plate 30 is preferably 0.1% or more and 10% or less. The haze value can be measured by a method based on JIS K7136 using a haze meter (manufactured by Murakami Color Research Laboratory, product number: HM-150).

  Furthermore, since the height h can be changed greatly between the light diffusion parts 50 forming the two extraction elements 53 adjacent to each other, the distribution of the emitted light quantity along the light guide direction is very high. Can be controlled.

  According to the second embodiment as described above, the extraction element 53 for extracting light from the light guide plate 30 can be effectively made inconspicuous. It can be effectively avoided that the design of the illuminating device 10 is impaired by sensing the extraction element 53 for extracting light from the light guide plate 30. Thereby, it becomes possible to provide the lighting device 10 with excellent design, and the lighting device 10 can be harmonized with respect to various installation positions.

  Further, according to the second embodiment, the second and third low refractive index layers 62 and 63 are provided so as to sandwich the extraction light guide layer 40 and the leading light layer 70. The interface where the light traveling through the base portion 45 and the main light layer 70 of the extraction light guide layer 40 is reflected is between the base portion 45 of the extraction light guide layer 40 and the second low refractive index layer 62 and the main light layer. 70 and the third low refractive index layer 63. That is, the interface where the light traveling in the base portion 45 and the main light layer 70 of the extraction light guide layer 40 is reflected is not exposed. For this reason, it is possible to effectively prevent damage to the interface and adhesion of foreign substances on which the light traveling in the base portion 45 and the main light layer 70 of the extraction light guide layer 40 is expected to be reflected. Thereby, it can prevent effectively that the reflection of the light for the light guide in the light-guide plate 30 is inhibited. Furthermore, in the second embodiment, the surface of the light guide plate 30 is formed by the cover layers 66 and 67 having better scratch resistance than the base portion 45, the main light layer 70 and the low refractive index layers 62 and 63. Yes. Accordingly, it is possible to more effectively prevent damage to the interface and adhesion of foreign substances on which light traveling through the light guide plate 30 is expected to be reflected.

  Various modifications can be made to the above-described second embodiment. Hereinafter, an example of modification will be described with reference to the drawings as appropriate. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above embodiment are used for the parts that can be configured in the same manner as in the above embodiment. A duplicate description is omitted.

  In the second embodiment described above, an example in which the groove 49 is formed on the second main surface 46 b of the base portion 45 and the light diffusion portion 50 is provided on the second main surface 41 b of the extraction light guide layer 40. Although shown, it is not limited to this. As shown in FIG. 9, a groove 49 may be formed on the first main surface 46 a of the base portion 45, and the light diffusion portion 50 may be disposed on the first main surface 41 a of the extraction light guide layer 40. Further, a groove 49 is formed in each of the first main surface 46a and the second main surface 46b of the base portion 45, and light diffusion is performed on both the first main surface 41a and the second main surface 41b of the extraction light guide layer 40. The part 50 may be arranged.

  In the second embodiment described above, the light guide plate 30 includes the second low refractive index layer 62, the first cover layer 66, the third low refractive index layer 63, and the second cover layer 67. . In such an example, in order to promote extraction of light from the light guide plate 30, it is preferable that at least one of the second low refractive index layer 62 and the first cover layer 66 contains a diffusion component. In order to promote the extraction of light from the light guide plate 30, it is preferable that at least one of the third low-refractive index layer 63 and the second cover layer 67 contains a diffusing component. On the other hand, the second low refractive index layer 62, the first cover layer 66, the third low refractive index layer 63, and the second cover layer 67 are not essential, and one or more of them can be omitted from the light guide plate 30.

  Further, in the above-described second embodiment, the second main surface 31b of the light guide plate 30 is covered with the housing 11, and only the first main surface 31a of the light guide plate 30 emits light. Not limited. As shown in FIG. 10, both the first main surface 31a and the second main surface 31b of the light guide plate 30 may emit light. That is, the illumination device 10 may have a pair of light emitting surfaces facing each other.

  Furthermore, in the above-described second embodiment, the example in which the first main surface 31a of the light guide plate 30 forms the light emitting surface of the lighting device 10 has been described, but the present invention is not limited thereto. Deflection means for deflecting the traveling direction of the light emitted from the light guide plate 30 is provided at a position facing the first main surface 31a of the light guide plate 30, and the light emitting surface 10a of the illumination device 10 is formed by this deflection means. You may make it do. Examples of the deflecting unit include a light collecting sheet having a prism surface or a lens surface formed on the light output side.

  Furthermore, in the above-described second embodiment, an example of the extraction light guide layer 40 and the extraction element 53 is shown, but the present invention is not limited to the above-described example. For example, as the extraction element 53, various extraction elements used in conventional light guide plates can be used. For example, the extraction light guide layer 40 has a sheet-like main portion and a diffusion component dispersed in the main portion, and the diffusion component that functions as the extraction element 53 is included in the extraction light guide layer 40. You may make it provide in the area | region which opposes both area | regions of the 1st area | region Z1 and the 2nd area | region Z2. Also in such an example, the extraction element 53 can be made inconspicuous in the light guide plate 30 including the region that emits light and the region that does not emit light.

  Still another example of the extraction light guide layer 40 and the light diffusion portion 50 is shown in FIG. In the example shown in FIG. 11, the extraction light guide layer 40 includes a plurality of extraction elements 53 arranged in the first direction d1, as in the second embodiment described above. The extraction element 53 is provided in a region facing both the first region Z1 and the second region Z2. In particular, the extraction element 53 is arranged adjacent to the main light layer 70 in the second region Z2. The refractive index difference between the extraction element 53 and the main light layer 70 is smaller than the refractive index difference between the first low refractive index layer 61 and the main light layer 70. Preferably, the extraction element 53 has the same refractive index as that of the main light layer 70. As a result, the light traveling in the main light layer 70 of the light guide plate 30 is not reflected from the interface between the main light layer 70 and the extraction element 53 in the second region Z2, but from the main light layer 70 to the extraction element 53. Can be incident. On the other hand, in the second region Z2, the first main surface 71a of the main light layer 70 forms an interface with air at a position where the extraction element 53 is not provided, and light incident on the interface with air is After total reflection, the light continues through the main light layer 70.

  In the example shown in FIG. 11, the extraction element 53 has a pair of side surfaces inclined with respect to the plate surface of the main light layer 70. In particular, in the example shown in FIG. 11, the cross-sectional shape of the extraction element 53 is an isosceles trapezoidal shape with the upper base facing the main light layer 70 side. The extraction element 53 may extend in a columnar shape in the second direction d2. The light L11 incident on the extraction element 53 via the first main surface 71a of the main light layer 70 in the second region Z2 is reflected by the side surface 54 of the extraction element 53, changes its traveling direction, and is emitted from the light guide plate 30. Become. Even in such a modification, the extraction element 53 can be made inconspicuous in the light guide plate 30 including the light emitting region and the non-light emitting region.

  In the example shown in FIG. 11, a first cover layer 66 is provided on the opposite side of the extraction light guide layer 40 formed by the extraction element 53 from the main light layer 70. The first cover layer 66 forms the outermost surface 10 a of the lighting device 10. In the example shown in FIG. 11, the second light source is provided at a position facing the opposite side surface 71d of the main light layer 70, and the opposite side surface 71d of the main light layer 70 functions as a second light incident surface. You may do it.

  In addition, although the some modification with respect to 2nd Embodiment mentioned above has been demonstrated above, naturally, it is also possible to apply combining several modifications suitably.

DESCRIPTION OF SYMBOLS 10 Illuminating device 10a Outermost surface 11 Housing | casing 20 Light source 22 Light emitter 30 Light guide plate 31a 1st main surface 31b 2nd main surface 31c Light incident surface 31d Opposite surface 40 Extraction light guide layer 41a 1st main surface 41b 2nd main surface 45 Base portion 46a First main surface 46b Second main surface 46c Incident side surface 46d Opposite side surface 49 Groove 50 Light diffusion portion 53 Extraction element 54 Side surface 61 First low refractive index layer 62 Second low refractive index layer 63 Third low refractive index Layer 66 First cover layer 67 Second cover layer 70 Main light guide layer 71a First main surface 71b Second main surface 71c Light incident side surface 71d Opposite side surface

Claims (11)

A base portion having a pair of main surfaces;
A plurality of light diffusion portions provided in the base portion;
A light guide plate comprising a take-out light guide layer. Any two light diffusion portions adjacent to each other in the first direction are spaced apart from each other along the first direction of the two light diffusion portions, and the two light diffusion portions along the normal direction of the extraction light guide layer. Heights h ₁ and h ₂ of the light diffusion portions of light, a refractive index n of the extraction light guide layer, a refractive index n _{L of} a layer adjacent to the extraction light guide layer from the one main surface side, The light guide plate according to claim 1, satisfying the following formula using:
tan (Arcsin (n _L / n)) ≤ d / (h ₁ + h ₂ )   The light guide plate according to claim 1 or 2, wherein a height of the light diffusion portion along a normal direction of the extraction light guide layer is not constant.   The height of the at least one light diffusing portion along the normal direction of the extraction light guiding layer is that of at least one other light diffusing portion located on one side in the first direction with respect to the one light diffusing portion. The light-guide plate as described in any one of Claims 1-3 higher than the height along the normal line direction of the said extraction light-guide layer.   The height along the normal direction of the extraction light guide layer of any one light diffusion part is the extraction of the other light diffusion part located on one side in the first direction with respect to the one light diffusion part The light guide plate according to any one of claims 1 to 4, wherein the light guide plate is at least a height along a normal direction of the light guide layer. A low refractive index layer disposed adjacent to the extraction light guide layer,
The light guide plate according to any one of claims 1 to 5, wherein a refractive index of the low refractive index layer is lower than a refractive index of the base portion of the extraction light guide layer.   A cover layer disposed on the opposite side of the low refractive index layer from the extraction light guide layer; and the low refractive index layer is a layer for joining the extraction light guide layer and the cover layer. The light guide plate according to claim 6, wherein   The light guide plate according to claim 7, wherein the cover layer has higher scratch resistance than the base portion of the extraction light guide layer. The base portion is formed with a plurality of grooves at intervals in the first direction on one main surface of the pair of main surfaces,
The light guide plate according to claim 1, wherein the light diffusion portion is provided in the groove.   Each light-diffusion part is a light-guide plate as described in any one of Claims 1-9 extended linearly in the direction non-parallel to the said 1st direction. The light guide plate according to any one of claims 1 to 10,
And a light source disposed to face the light incident side surface of the light guide plate.

Images