WO2011093173A1

WO2011093173A1 - Light-guiding plate, lighting device, and liquid-crystal display device

Info

Publication number: WO2011093173A1
Application number: PCT/JP2011/050754
Authority: WO
Inventors: 啓介塚田
Original assignee: 日本ゼオン株式会社
Priority date: 2010-01-29
Filing date: 2011-01-18
Publication date: 2011-08-04
Also published as: TW201131225A

Abstract

Disclosed is a light-guiding plate (101) that guides light in a prescribed direction (X), and comprises a light introduction face (110) that introduces light; a light extraction face (120) that extracts light that is introduced via the light introduction face (110); and a rear face (130) that is located on the opposite side from the light extraction face (120). At least one of the light extraction face (120) or the rear face (130) further comprises an uneven structure (A), further comprising an anisotropic shape wherein the dimension in the prescribed direction (X) is greater than the dimension of a direction (Y) that is orthogonal to the prescribed direction (X), as seen from a parallel direction (Z) in the direction of the extraction of the light.

Description

Light guide, illumination device, and liquid crystal display device

The present invention relates to a light guide, an illumination device including the same, and a liquid crystal display device.

Liquid crystal display devices are widely used as display units for liquid crystal televisions, personal computers, mobile phones and the like. The liquid crystal display device generally includes a liquid crystal panel and an illumination device called a backlight device that supplies light to the back surface of the liquid crystal panel.

Examples of the backlight device include a lighting device that combines a plate-like light guide (hereinafter, referred to as “light guide plate” as appropriate) and a light source that emits light from the side to the light guide plate. For example, Patent Documents 1 to 3 can be cited as references describing such a type of lighting device. In this type of lighting device, light emitted from a light source is introduced into a light guide plate from a light introduction surface located on a side surface of the light guide plate, and the introduced light is light located on the front surface or the back surface of the light guide plate. By emitting from the extraction surface, surface light emission is performed.

JP 2001-92370 A JP 2003-114432 A JP 2009-224030 A

In recent years, local dimming has attracted attention in the field of liquid crystal display devices. Local dimming is, for example, a technique that does not irradiate light evenly over the entire surface of the liquid crystal panel, but irradiates light only in a desired region or changes the light irradiation intensity for each region. Local dimming is expected to improve the image quality of liquid crystal display devices (for example, improve contrast and reduce afterimages) and save energy.

Therefore, it is desired to develop a technique for realizing local dimming even in the above-described type of lighting device. In order to realize local dimming with the above-mentioned type of lighting device, it is required to selectively extract light from a light extraction surface in a desired region of the light guide plate, and to prevent light from being extracted from other regions. Is required to be suppressed. However, the conventional light guide plate has been developed for the purpose of extracting light evenly from the entire area, and it has been difficult to selectively extract light from a desired area. In particular, in the conventional light guide plate, the light to be guided is guided so as to spread over a wide area of the light guide plate, so that the light guided outside the desired area is not used for irradiation of the liquid crystal panel and is wasted. On the contrary, there was a possibility that it would be a factor of image quality degradation.

Conventionally, in order to prevent the light guided from spreading, a plurality of light guide plates having a small size are arranged, and a space or a partition is provided at the boundary portion. However, light leakage from the boundary portion or dark portion may occur, preventing uniform illumination, and high optical performance may not be realized. In the above case, when a plurality of light guide plates having a small size are arranged, the number of processes and cost tend to increase in terms of manufacturing.

The present invention has been made in view of the above problems, and a light guide capable of selectively extracting light from a light extraction surface in a desired region, and illumination capable of realizing local dimming using the light guide. An object is to provide a device and a liquid crystal display device.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has at least one of the light extraction surface of the light guide and the back surface located on the opposite side of the light extraction surface to have a shape viewed from the light extraction direction. By providing a concavo-convex structure having a predetermined anisotropy, the light guiding direction can be controlled by internal reflection on the surface of the concavo-convex structure, so that light can be selectively extracted from a light extraction surface in a desired region. As a result, the present invention has been completed.
That is, according to the present invention, the following [1] to [18] are provided.

[1] A light introduction surface for introducing light, a light extraction surface for extracting light introduced from the light introduction surface, and a back surface positioned on the opposite side of the light extraction surface, and introduced from the light introduction surface A light guide that guides the light in a predetermined direction,
As seen from a direction parallel to the light extraction direction, the concavo-convex structure A having an anisotropic shape in which the dimension in the predetermined direction is larger than the dimension in the direction orthogonal to the predetermined direction is formed on the light extraction surface and the back surface. A light guide having at least one of the surfaces.
[2] The light guide according to [1], wherein the uneven structure A is provided on both the light extraction surface and the back surface.
[3] The light guide according to [1] or [2], wherein the main axis of the anisotropic shape of the concavo-convex structure A viewed from a direction parallel to the light extraction direction is parallel to the predetermined direction.
[4] The light guide according to any one of [1] to [3], wherein the concave portions of the concave-convex structure A are continuous.
[5] The light guide according to any one of [1] to [4], wherein at least one of the concave portion and the convex portion of the concavo-convex structure A has a flat portion.
[6] Any one of [1] to [5], wherein the light guide has a light extraction structure for extracting light guided through the light guide from the light extraction surface at a portion having the uneven structure A. The light guide according to one item.
[7] The light guide according to [6], wherein the light extraction structure is a concavo-convex structure B having a main axis of the anisotropic shape in a direction intersecting with the main axis of the anisotropic shape of the concavo-convex structure A.
[8] The light guide according to [7], wherein the anisotropic main axis of the concavo-convex structure A is orthogonal to the anisotropic main axis of the concavo-convex structure B.
[9] The light guide according to [6], wherein the light extraction structure is unevenness formed on a surface of the uneven structure A.
[10] The light guide according to any one of [6] to [9], wherein the density or size of the light extraction structure increases with distance from the light introduction surface.
[11] The light guide according to [6], wherein the light extraction structure is a light diffusing agent present in the light guide.
[12] The light guide according to any one of [1] to [11], wherein the concavo-convex structure A has a bowl-shaped convex portion.
[13] The light guide according to [7] or [8], wherein the concavo-convex structure B has a bowl-shaped convex portion.
[14] The light guide according to [12] or [13], wherein the bowl-shaped convex portion includes a prism having a triangular cross section or a lenticular.
[15] An illumination device comprising: the light guide according to any one of [1] to [14]; and a light source that irradiates light to a light introduction surface of the light guide.
[16] A plurality of the light sources are provided,
The lighting device according to [15], wherein the plurality of light sources are dimmable individually or in groups.
[17] The illumination device according to [15] or [16], wherein the light source is an LED.
[18] A liquid crystal panel;
A liquid crystal display device comprising: the illumination device according to any one of [15] to [17] provided on a back side of the liquid crystal panel.

According to the light guide of the present invention, light can be selectively extracted from the light extraction surface in a desired region.
According to the illumination device and the liquid crystal display device of the present invention, local dimming is possible.

FIG. 1 is a perspective view schematically showing an outline of a lighting apparatus as a first embodiment of the present invention. FIG. 2 is a perspective view schematically showing a state in which a part of the light guide according to the first embodiment of the present invention is cut out and viewed from the light extraction surface side. FIG. 3 is a plan view of one of the prisms formed on the light extraction surface of the light guide according to the first embodiment of the present invention, viewed from the light extraction surface side in the Z-axis direction. FIG. 4 is a perspective view schematically showing a state in which a part of the light guide according to the first embodiment of the present invention is cut out and viewed from the back side. FIG. 5 is a plan view of one of the prisms formed on the back surface of the light guide according to the first embodiment of the present invention as viewed from the back surface side in the Z-axis direction. FIG. 6 is an enlarged view of a cross section obtained by cutting the light guide along a plane perpendicular to the X-axis direction in order to explain the state of internal reflection of light guided through the light guide according to the first embodiment of the present invention. FIG. FIG. 7 is a perspective view schematically showing an outline of a lighting apparatus as a second embodiment of the present invention. FIG. 8 is a perspective view schematically showing a state in which a part of the light guide according to the second embodiment of the present invention is cut out and viewed from the light extraction surface side. FIG. 9 is a plan view of one of the prisms formed on the light extraction surface of the light guide according to the second embodiment of the present invention, as viewed from the light extraction surface side in the Z-axis direction. FIG. 10 is a perspective view schematically showing a state in which a part of the light guide according to the second embodiment of the present invention is cut out and viewed from the back side. FIG. 11 is a plan view of one of the prisms formed on the back surface of the light guide according to the second embodiment of the present invention as viewed from the back surface side in the Z-axis direction. FIG. 12 is a perspective view schematically showing an outline of a lighting apparatus as a third embodiment of the present invention. FIG. 13: is a perspective view which shows typically a mode that a part of light guide which concerns on 3rd embodiment of this invention was cut out, and it saw from the light extraction surface side. FIG. 14 is a plan view of two adjacent prisms as the concavo-convex structure A formed on the light extraction surface of the light guide according to the third embodiment of the present invention, as viewed from the light extraction surface side in the Z-axis direction. FIG. FIG. 15: is sectional drawing which shows typically the cross section which cut the light guide which concerns on 3rd embodiment of this invention with the surface perpendicular | vertical to the Y-axis direction. FIG. 16: is a perspective view which shows typically a mode that a part of light guide which concerns on three embodiment of this invention was cut out, and it saw from the back surface side. FIG. 17 is a plan view of two adjacent prisms as the concavo-convex structure A formed on the back surface of the light guide according to the third embodiment of the present invention, as viewed from the back surface side in the Z-axis direction. FIG. 18 is an enlarged view of a cross section obtained by cutting the light guide along a plane perpendicular to the Y-axis direction in order to explain how light guided through the light guide according to the third embodiment of the present invention is extracted. It is sectional drawing shown typically. FIG. 19 is a perspective view schematically showing an outline of a lighting apparatus as a fourth embodiment of the present invention. FIG. 20 is a perspective view schematically showing a state where a part of the light guide according to the fourth embodiment of the present invention is cut out and viewed from the light extraction surface side. FIG. 21 is a perspective view schematically showing a state in which a part of the light guide according to the fourth embodiment of the present invention is cut out and viewed from the back surface side. FIG. 22 is a perspective view schematically showing an outline of a lighting apparatus as a fifth embodiment of the present invention. FIG. 23 is a cross-sectional view schematically showing a cross section of the light guide according to the fifth embodiment of the present invention cut along a plane perpendicular to the Y-axis direction. FIG. 24 is a perspective view schematically showing an outline of a lighting apparatus as a sixth embodiment of the present invention. FIG. 25 is a perspective view schematically showing a state where a part of the light guide according to the sixth embodiment of the present invention is cut out and viewed from the light extraction surface side. FIG. 26 is a perspective view schematically showing a state in which a part of the light guide according to the sixth embodiment of the present invention is cut out and viewed from the back side. FIG. 27 is an enlarged view of a cross section of the light guide cut along a plane perpendicular to the X-axis direction in order to explain the internal reflection of light guided through the light guide according to the sixth embodiment of the present invention. FIG. FIG. 28 is a perspective view schematically showing an outline of a liquid crystal display device as a seventh embodiment of the present invention. FIG. 29 is a diagram schematically showing an illumination device as a modification of the first embodiment. FIG. 30 is a perspective view schematically showing a state in which a part of a light guide as a modification of the third embodiment is cut out and viewed from the light extraction surface side. FIG. 31 is a perspective view schematically showing a state in which a part of the light guide according to an embodiment of the present invention is cut out and viewed from the light extraction surface 120 side. FIG. 32 is a plan view of one of the concavo-convex structures A formed on the light extraction surface of the light guide according to the embodiment of the present invention, as viewed from the light extraction surface side in the Z-axis direction. FIG. 33 is a plan view for explaining simulation conditions set in the simulation performed in the first embodiment. FIG. 34 shows the light spread width W ₅₀ measured in Examples 1 to 4, 7 to 23 of the present invention and Comparative Example 1, and the inclination angles of the prisms formed on the light extraction surface and the back surface of the light guide. It is a graph showing the relationship. FIG. 35 shows the light spread width W ₅ measured in Examples 1 to 4, 7 to 23 of the present invention and Comparative Example 1, and the inclination angles of the prisms formed on the light extraction surface and the back surface of the light guide. It is a graph showing the relationship.

Hereinafter, the present invention will be described in detail with reference to embodiments and examples, but the present invention is not limited to the following embodiments and examples, and the claims of the present invention and equivalents thereof. Any change can be made without departing from the scope.
In the following description, the symbol “A” of “concave / convex structure A” and the symbol “B” of “concavo-convex structure B” are the symbols appended to distinguish the element to which the symbol is attached from other elements. Yes, it has no meaning other than element distinction. Moreover, unless the direction of the component is “parallel” and “orthogonal”, unless otherwise specified, an error may be included within a range that does not impair the effects of the present invention, for example, within a range of ± 5 °. Further, “along” in a certain direction means “in parallel” in a certain direction. Furthermore, in the description of the position of the light guide, “front” refers to a position close to the light introduction surface, and “back” refers to a position far from the light introduction surface. “Uneven structure” means “concave structure and / or convex structure”, and “uneven structure” means “concave and / or convex”.

[First embodiment]
FIG. 1 is a perspective view schematically showing an outline of a lighting apparatus as a first embodiment of the present invention. As shown in FIG. 1, the illuminating device 1 as 1st embodiment of this invention is equipped with the plate-shaped light guide 101, the some light source 201, and the light modulation apparatus 301 which light-modulates the light source 201. As shown in FIG.

The light guide 101 includes a light introduction surface 110 that introduces light into the light guide 101, a light extraction surface 120 that extracts the light introduced from the light introduction surface 110 to the outside of the light guide 101, and a light extraction surface. 120 and a back surface 130 located on the opposite side to 120. In this light guide body 101, the light introduced into the light guide body 101 from the light introduction surface 110 is guided in a predetermined direction while being internally reflected by the light extraction surface 120 and the back surface 130, and is guided there. Are extracted from the light extraction surface 120. Here, when light is extracted from the back surface 130, a reflection sheet can be installed on the back surface 130 side of the light guide 101, and the extracted light can be reflected and guided to the light extraction surface 120. Note that the direction in which light is guided (hereinafter referred to as “light guiding direction” as appropriate) including the predetermined direction is within the light guide 101 when viewed from the light extraction direction unless otherwise specified. Indicates the direction in which light is guided. Therefore, when referring to the light guide direction, the Z-axis direction described later is not a problem unless otherwise specified.

Here, among the directions parallel to the light extraction surface 120, the direction parallel to the predetermined direction is defined as the X-axis direction. Of the directions parallel to the light extraction surface 120, the direction orthogonal to the X-axis direction is taken as the Y-axis direction. Further, the normal direction of the light extraction surface 120 is taken as the Z-axis direction. In the present embodiment, the light guide 101 has a rectangular plate shape, the X-axis direction is parallel to the short side direction of the light extraction surface 120 of the light guide 101, and the Y-axis direction is the light guide. 101 is parallel to the long side direction of the light extraction surface 120, the Z-axis direction is parallel to the thickness direction of the light guide 101, and the X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other. And

The light introduction surface 110 is a side surface of the light guide 101 and is a surface located at the ends of the light extraction surface 120 and the back surface 130. This light introduction surface 110 is a surface orthogonal to the X-axis direction. That is, the light introduction surface 110 is set to be orthogonal to a predetermined direction in which light is guided. When light is irradiated perpendicularly from the light source 201 to such a light introduction surface 110, reflection on the light introduction surface 110 can be suppressed and light introduction efficiency can be increased. In addition, refraction at the light introduction surface 110 at the time of introduction can be suppressed, and the traveling direction of light can be stably directed in a desired light guide direction (that is, the X-axis direction). Spreading can be stably suppressed.
The light introduction surface 110 may be provided with irregularities such as a lens in order to increase the light introduction efficiency and further suppress the spread of light in the Y-axis direction. Good. In addition, in order to suppress bright lines in the vicinity of the light introduction surface 110 derived from the light source 201, the light introduction surface 110 may be an irregular rough surface (a surface on which minute irregularities are randomly formed) or a bowl-shaped rough surface. Good. In the present embodiment, the light introduction surface 110 will be described as a flat plane.

The light extraction surface 120 is one of the main surfaces of the light guide body 101. In the light guide 101, light is emitted from the light extraction surface 120 in a predetermined extraction direction. Normally, the light extraction direction from the light extraction surface 120 is a direction inclined from the normal direction of the light extraction surface 120 in the direction opposite to the light source 201, but here is parallel to the normal direction of the light extraction surface 120. To do. Also in this embodiment, the description will be made assuming that the light extraction direction from the light extraction surface 120 is parallel to the Z-axis direction, which is the normal direction of the light extraction surface 120.

FIG. 2 is a perspective view schematically showing a state in which a part of the light guide body 101 according to the first embodiment of the present invention is cut out and viewed from the light extraction surface 120 side. As shown in FIG. 2, a plurality of prisms 121 are formed on the light extraction surface 120 as the concavo-convex structure A.
Each prism 121 is a bowl-shaped convex portion extending in the X-axis direction, and a plurality of prisms 121 are formed side by side in the Y-axis direction.
In addition, a plurality of prisms 121 are formed on the entire light extraction surface 120 side by side in the Y-axis direction. Thereby, the entire surface of the light extraction surface 120 has the concavo-convex structure A.

Each prism 121 is a prism having a triangular section in which a section cut by a plane perpendicular to the X-axis direction is a triangle. Therefore, the prism 121 has two

inclined surfaces

122 and 123 that are not parallel to the Y-axis direction (that is, intersect with the Y-axis). Such

inclined surfaces

122 and 123 can internally reflect light guided in the light guide 101 so as not to spread in the Y-axis direction. That is, when the light repeats internal reflection at the

inclined surfaces

122 and 123, the direction of the Y-axis direction component of the light repeats reversal, so that most of the guided light is in one of the Y-axis directions or On the other hand, it cannot continue continuously and does not spread in the Y-axis direction.

The average inclination angle θ of the

slopes

122 and 123 of the prism 121 is preferably 15 ° or more, more preferably 25 ° or more, and particularly preferably 30 ° or more. The upper limit is less than 90 °. Here, the average inclination angle θ of the

slopes

122 and 123 is an average value of the inclination angles of the

slopes

122 and 123 with respect to the light extraction surface 120 (see FIG. 6). Since the light extraction surface 120 has a concavo-convex structure A, it is not a flat plane when viewed microscopically. However, since the concavo-convex structure A has a small dimension in the Z-axis direction, when viewed macroscopically, the light extraction surface 120 is It can be handled as a flat plane. Therefore, the average inclination angle θ can be understood as an average value of angles formed between the

inclined surfaces

122 and 123 and the light extraction surface 120 when viewed macroscopically. By setting the average inclination angle θ in the above range, the light guided in the light guide 101 is effectively prevented from spreading in the Y-axis direction, and the light guide direction can be controlled efficiently. .

FIG. 3 is a view of one of the prisms 121 formed on the light extraction surface 120 of the light guide 101 according to the first embodiment of the present invention, as viewed from the light extraction surface side in the Z-axis direction. That is, FIG. 3 shows a state in which one of the prisms 121 is viewed from a direction parallel to the light extraction direction. As shown in FIG. 3, when viewed from the light extraction surface side in the Z-axis direction, the prism 121 has an anisotropic shape. Specifically, the length (the dimension in the X-axis direction) Lx of the prism 121 is larger than the width (the dimension in the Y-axis direction in this embodiment) Ly. Therefore, the prism 121 has an anisotropic shape in which the dimension Lx in the X-axis direction, which is a predetermined direction in which light is guided, is larger than the dimension in the Y-axis direction orthogonal to the X-axis direction. This increases the frequency of internal reflection that inverts the direction of the Y-axis direction component of the light on the

inclined surfaces

122 and 123 of the light guided through the light guide 101, and thereby increases the Y-axis direction. The above action of suppressing the spread of light can be effectively exhibited. Therefore, it is possible to effectively suppress the light guided in the light guide 101 from spreading in the Y-axis direction.

The specific length Lx of the prism 121 is assumed to be the same as the dimension of the light guide 101 in the X-axis direction in the light guide 101 of the present embodiment. As a result, the entire light extraction surface 120 can exhibit the effect of suppressing the spread of light in the Y-axis direction due to internal reflection at the

inclined surfaces

122 and 123. Moreover, since the recessed part (valley part) 124 (refer FIG. 2, FIG. 6) formed between the prisms 121 will be continuously formed in the whole X-axis direction of the light guide 101, a light guide. It is possible to effectively suppress the light guided in the Y-axis direction from spreading in the Y-axis direction, to prevent close contact with the optical sheet disposed in the vicinity of the light guide 101, or to be disposed in the vicinity of the light guide 101. The scratch of the light guide 101 due to rubbing with the optical sheet can be suppressed.

On the other hand, the width Ly of the prism 121 is usually 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and usually 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less. If it is too small, there is a tendency that light is scattered due to a diffraction phenomenon or that the production becomes difficult. If it is too large, the brightness and darkness of the portion from which light is extracted and the portion from which light is not extracted can be visually recognized, which may cause an optical defect.

In the present invention, the ratio of the dimension of the concavo-convex structure A to the dimension of the light guide direction and the dimension orthogonal to the predetermined direction as viewed from the direction parallel to the light extraction direction (in the example of the prism 121, the length of the prism 121). The ratio of Lx to width Ly (Lx / Ly) can be determined as appropriate depending on the number of light sources 201, the arrangement and emission intensity, the shape and dimensions of the light extraction surface 120, and the like. Such a ratio is usually 1.5 or more, preferably 2.0 or more, more preferably 5.0 or more, and usually 200000 or less, more preferably 100000 or less, and more preferably 50000 or less. If it is too small, it may not be possible to prevent the light guided in the light guide 101 from spreading in the Y-axis direction. Further, the length Lx depends on the length of the light guide body 101, but if the ratio is too large, the width Ly becomes small and it is difficult to manufacture.

Further, the height H of the prism 121 (in this embodiment, the dimension in the Z-axis direction; see FIG. 6) H is usually 1.0 μm or more, preferably 2.0 μm or more, more preferably 3.0 μm or more. Usually, it is 500 micrometers or less, Preferably it is 400 micrometers or less, More preferably, it is 300 micrometers or less. If it is too small, production becomes difficult due to the limit of processing accuracy, and if it is too large, it can be visually recognized and may cause an optical defect.

As shown in FIG. 3, when viewed from the light extraction surface side in the Z-axis direction, the principal axis PA of the anisotropic shape of the prism 121 is parallel to the X-axis direction. Here, the principal axis PA of the anisotropic shape of the prism 121 refers to an axis along the longitudinal direction in the shape of the prism 121 viewed from the Z-axis direction. Since the prism 121 exhibits the effect of guiding light along the principal axis PA by internal reflection at the

inclined surfaces

122 and 123, the anisotropic principal axis PA of the prism 121 is parallel to the X-axis direction. Light can be stably guided along the X-axis direction.

The back surface 130 is one of the main surfaces of the light guide 101 and is a surface parallel to the light extraction surface 120. On the back surface 130, light guided through the light guide 101 is internally reflected. For this reason, the back surface 130 may be called a reflective surface. In addition, in order to stably reflect light internally on the back surface 130, the back surface 130 may be provided with a reflective layer such as a metal layer, a resin-made scattering layer, or a combination thereof.

FIG. 4 is a perspective view schematically showing a state in which a part of the light guide body 101 according to the first embodiment of the present invention is cut out and viewed from the back surface 130 side. FIG. 5 is a view of one of the prisms 131 formed on the back surface 130 of the light guide body 101 according to the first embodiment of the present invention as viewed from the back surface side in the Z-axis direction.
As shown in FIG. 4, a prism 131 is formed on the back surface 130 as the concavo-convex structure A. The prism 131 is formed in the same manner as the prism 121 on the light extraction surface 120. That is, the prism 131 is formed on the entire back surface 130. Each prism 131 is a prism having a triangular cross section, and has two

inclined surfaces

132 and 133, respectively. Furthermore, as shown in FIG. 5, when viewed from the back side in the Z-axis direction, the length of the prism 131 (in this embodiment, the dimension in the X-axis direction) Lx is the width of the prism 131 (in this embodiment, It is larger than the dimension Y in the Y-axis direction. In addition, concave portions (valley portions) 134 (see FIGS. 4 and 6) formed between the prisms 131 are continuously formed in the entire X-axis direction of the light guide 101. Furthermore, as viewed from the Z-axis direction, the principal axis PA of the anisotropic shape of the prism 131 is parallel to the X-axis direction. With these configurations, similarly to the light extraction surface 120, the back surface 130 can suppress the spread of the guided light in the Y-axis direction. The average inclination angle θ of the

inclined surfaces

132 and 133 of the prism 131 is preferably 15 ° or more, more preferably 25 ° or more, and particularly preferably 30 ° or more. The upper limit is less than 90 °. When at least one of the prism 121 and the prism 131 satisfies this condition, the spread of the guided light in the Y-axis direction can be suppressed.

The light source 201 shown in FIG. 1 is a device that irradiates light to the light introduction surface 110 of the light guide 101. The light source 201 is usually installed such that its axis (that is, the direction of the principal ray of emitted light) is parallel to the X-axis direction. As the light source 201, for example, an LED (Light Emitting Diode) is used. LEDs are high light emission efficiency and are excellent light sources from the viewpoint of energy saving. The LED is supplied with electric power from a power source (not shown), and can be individually dimmed by the supplied electric power.

However, from the viewpoint of realizing local dimming, the light source 201 can selectively irradiate a desired region of the light introduction surface 110 with light. Therefore, the illumination device 1 of the present embodiment has the following configuration.
That is, the light guide 101 is divided into a plurality of regions 101a to 101h when viewed from the Z-axis direction, and each of the regions 101a to 101h has a rectangular shape extending along the X-axis direction. The light introduction surface 110 is divided into regions 110a to 110h located on the front side in the X-axis direction of the regions 101a to 101h. Note that the regions 101a to 101h and the regions 110a to 110h are virtually set for controlling the light emission position of the lighting device 1, and are not usually separated by physical boundaries.

In this case, the lighting device 1 includes a plurality of light sources 201, and the light sources 201 are provided at positions in front of the regions 110a to 110h of the light introduction surface 110. Each light source 201 is connected to a light control device 301 that controls the light source 201. The light control device 301 is a device that adjusts the presence / absence and supply amount of power to the light source 201. Therefore, the light control device 301 adjusts the power supplied to each light source 201 so that light can be selectively irradiated from each light source 201 to the regions 110a to 110h of the light introduction surface 110 with desired brightness. It has become.

The dimming device 301 includes, in terms of hardware, an arithmetic device such as a CPU (Central Processing Unit), a memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), and an interface unit such as an AD conversion unit. These are composed of variable resistors and the like, and these function as the above-mentioned dimmers.

Since the illuminating device 1 as the first embodiment of the present invention is configured as described above, the light emitted from the light source 201 enters the light introduction surface 110 and is introduced into the light guide 101 to be guided. After being guided through the light body 101, the light is extracted from the light extraction surface 120 to the outside. Further, local dimming can be efficiently performed by controlling the light emission of the light source 201. Hereinafter, a mechanism capable of performing efficient local dimming will be described by taking as an example a case where light is selectively extracted from the light extraction surface 120 in the region 101a.

When light is selectively extracted from the light extraction surface 120 in the region 101a, the light control device 301 adjusts the amount of power supplied to the light source 201, so that the light source positioned in front of the region 110a of the light introduction surface 110 is adjusted. Light is selectively emitted from 201. The irradiated light enters the region 110 a of the light introduction surface 110 and is introduced into the light guide 101. The light introduced into the light guide body 101 is guided toward the back along the X-axis direction while repeating internal reflection on the light extraction surface 120 and the back surface 130.

FIG. 6 is a cross-sectional view of the light guide 101 taken along a plane perpendicular to the X-axis direction in order to explain the state of internal reflection of light guided through the light guide 101 according to the first embodiment of the present invention. It is sectional drawing which expands and shows typically. In FIG. 6, an arrow A indicates a component perpendicular to the X-axis direction among light vectors guided through the light guide 101. As shown in FIG. 6, the light A guided in the light guide 101 repeats internal reflection on the

inclined surfaces

122 and 123 of the light extraction surface 120 and the

inclined surfaces

132 and 133 of the back surface 130. Due to internal reflection, the light A that has traveled to the right in the figure proceeds to the left in the figure. Similarly, light that has traveled to the left in the figure proceeds to the right in the figure. For this reason, most of the light guided in the light guide 101 cannot continue to proceed continuously in one direction or the other direction in the Y-axis direction. Therefore, the light guided in the light guide 101 does not spread in the Y-axis direction but is guided in the region 101a of the light guide 101 along the X-axis direction.

In FIG. 6, since the light A is incident on the back surface 130 at a small incident angle, the light A appears to be extracted from the back surface 130 to the outside. However, in reality, the light A has a component in the X-axis direction larger than a component perpendicular to the X-axis direction. Therefore, as shown in FIG. 6, even when the incident angle of the component perpendicular to the X-axis direction in the light vector is small, the incident angle of the light to the back surface 130 is actually large and the light can be internally reflected. There is. The same applies to the internal reflection at the light extraction surface 120.

The light guided in the region 101a of the light guide body 101 along the X-axis direction is extracted from the light extraction surface 120 in the region 101a. At this time, since the guided light does not spread in the Y-axis direction, the light is not extracted from the light extraction surfaces 120 in the regions 101b to 101h other than the region 101a, or the extraction amount even if it is extracted. Becomes a small amount. In this way, local dimming is realized by selectively extracting light from the light extraction surface 120 in the desired region 101a among the regions 101a to 101h.

At this time, since the prism 121 and the prism 131 corresponding to the concavo-convex structure A are provided on both the light extraction surface 120 and the back surface 130, the light to be guided spreads in the Y-axis direction only on one side. In comparison, it can be further suppressed.
In addition, since the principal axis PA of the anisotropic shape of the prism 121 and the prism 131 is parallel to the X-axis direction, light can be stably guided along the X-axis direction.
Furthermore, since the

recesses

124 and 134 of the concavo-convex structure A are continuous along the X-axis direction, the light guided in the light guide 101 can be more effectively suppressed from spreading in the Y-axis direction, It is possible to prevent the light guide 101 from being in close contact with the optical sheet disposed close to the light guide 101, or to suppress the light guide 101 from being scratched by rubbing with the optical sheet disposed close to the light guide 101.

[Second Embodiment]
FIG. 7 is a perspective view schematically showing an outline of a lighting apparatus as a second embodiment of the present invention. FIG. 8 is a perspective view schematically illustrating a state in which a part of the light guide according to the second embodiment of the present invention is cut out and viewed from the light extraction surface side. FIG. 9 is a view of one of the prisms formed on the light extraction surface of the light guide according to the second embodiment of the present invention, viewed from the light extraction surface side in the Z-axis direction. FIG. 10 is a perspective view schematically showing a state in which a part of the light guide according to the second embodiment of the present invention is cut out and viewed from the back side. FIG. 11 is a view of one of the prisms formed on the back surface of the light guide according to the second embodiment of the present invention as viewed from the back surface side in the Z-axis direction. 7 to 11, the same reference numerals as those in FIGS. 1 to 6 denote the same parts as those in FIGS. 1 to 6.

As shown in FIG. 7, the illuminating device 2 as 2nd embodiment of this invention is equipped with the plate-shaped light guide 102, the some light source 201, and the light control apparatus 301 which light-modulates the light source 201. As shown in FIG. Here, the light source 201 and the light control device 301 are the same as in the first embodiment. The light guide 102 is the same as the light guide 101 of the first embodiment except for the shapes of the prism 121 and the prism 131 that the light extraction surface 120 and the back surface 130 have.

As shown in FIGS. 8 and 9, the prism 121 according to the second embodiment is the same as the prism 121 of the first embodiment, except that the prism 121 has a flat portion 125 having a flat surface orthogonal to the Z-axis direction. It has become. As shown in FIGS. 10 and 11, the prism 131 according to the second embodiment is the same as the prism 131 of the first embodiment except that the prism 131 has a flat portion 135 having a flat surface orthogonal to the Z-axis direction. It is the same. That is, the prism 121 according to the second embodiment has a trapezoidal cross section, and has a flat portion 125 between the slope 122 and the slope 123. The prism 131 according to the second embodiment has a trapezoidal cross section, and has a flat portion 135 between the slope 132 and the slope 133. Since the

inclined surfaces

122 and 123 and the

inclined surfaces

132 and 133 are provided, the light guided through the light guide 102 is also internally reflected by the prism 121 and the prism 131 according to the second embodiment so as not to spread in the Y-axis direction. Be able to. Furthermore, since the flat portion 125 and the flat portion 135 are provided, it is possible to easily remove the light guide 102 from the mold at the time of manufacturing the light guide 102, and to reduce the number of steps for manufacturing the mold.

Since the illuminating device 2 as the second embodiment of the present invention is configured as described above, it can be used similarly to the illuminating device 1 according to the first embodiment, and the same advantages can be obtained.
Furthermore, in the illuminating device 2 according to the second embodiment, the light guide 102 can be easily taken out from the mold, and the number of steps for producing the mold can be reduced.

[Third embodiment]
FIG. 12 is a perspective view schematically showing an outline of a lighting apparatus as a third embodiment of the present invention. FIG. 13: is a perspective view which shows typically a mode that a part of light guide which concerns on 3rd embodiment of this invention was cut out, and it saw from the light extraction surface side. FIG. 14 is a diagram of two adjacent prisms as the concavo-convex structure A formed on the light extraction surface of the light guide according to the third embodiment of the present invention, viewed from the light extraction surface side in the Z-axis direction. It is. FIG. 15: is sectional drawing which shows typically the cross section which cut the light guide which concerns on 3rd embodiment of this invention with the surface perpendicular | vertical to the Y-axis direction. FIG. 16: is a perspective view which shows typically a mode that a part of light guide which concerns on three embodiment of this invention was cut out, and it saw from the back surface side. FIG. 17 is a view of two adjacent prisms as the concavo-convex structure A formed on the back surface of the light guide according to the third embodiment of the present invention, as viewed from the back surface side in the Z-axis direction. 12 to 17, the same reference numerals as those in FIGS. 1 to 11 denote the same parts as those in FIGS.

As shown in FIG. 12, the illuminating device 3 as 3rd embodiment of this invention is equipped with the plate-shaped light guide 103, the several light source 201, and the light modulation apparatus 301 which light-modulates the light source 201. As shown in FIG. Here, the light source 201 and the light control device 301 are the same as in the first embodiment. The light guide 103 has a prism 141 in addition to the prism 121 on the light extraction surface 120, which is a part having the prism 121, and a prism 151 in addition to the prism 131 on the back surface 130, which is a part having the prism 131. Except this, it is the same as the light guide 101 of the first embodiment.

As shown in FIG. 13, a prism 141 is formed on the light extraction surface 120 of the light guide 103 so as to overlap the prism 121. The prism 141 is a light extraction structure that extracts light guided through the light guide 103 from the light extraction surface 120, and is formed by a hook-shaped protrusion extending in a predetermined direction. Therefore, the prism 141 has a concavo-convex structure B having an anisotropic shape when viewed from the Z-axis direction, which is a direction parallel to the light extraction direction.

Each prism 141 is the same as the prism 121 in that it has a triangular cross section. However, as shown in FIG. 14, when viewed from the light extraction surface side in the Z-axis direction, the anisotropic main axis PB of the prism 141 extends in a direction intersecting the anisotropic main axis PA of the prism 121. It is supposed to be. Since the prism 121 has the effect of guiding light along the main axis PA, the direction of the anisotropic main axis PB of the prism 141 is set so as to intersect the anisotropic main axis PA of the prism 121. As a result, light can be easily extracted by the

slopes

142 and 143 of the prism 141. Among these, from the viewpoint of further increasing the light extraction efficiency, it is preferable that the anisotropic main axis PA of the prism 121 and the anisotropic main axis PB of the prism 141 are orthogonal to each other.

Further, unlike the prism 121, the prism 141 is formed side by side with a predetermined distance D between adjacent prisms 141 as shown in FIG. Here, the interval D between the prisms 141 is set so as to become narrower from the front in the X-axis direction toward the back. Accordingly, the formation density of the prism 141 increases as the distance from the light introduction surface 110 increases, and the light can be efficiently extracted by the prism 141 as the distance from the light introduction surface 110 increases. Usually, since the amount of light guided is smaller as the position is farther from the light introduction surface 110, a light extraction structure (here, the prism 141) that can extract light with higher extraction efficiency as the distance from the light introduction surface 110 is provided. Thus, light can be extracted uniformly from the light extraction surface 120 in the X-axis direction.

The specific interval D of the prism 141 is usually 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and usually 10,000 μm or less, preferably 5000 μm or less, more preferably 3000 μm or less. If it is too small, there is a tendency that light is scattered due to a diffraction phenomenon or that the production becomes difficult. If it is too large, the brightness and darkness of the portion from which light is extracted and the portion from which light is not extracted can be visually recognized, which may cause an optical defect.

The width of the prism 141 (in this embodiment, the dimension in the X-axis direction, see FIG. 14) lx is usually 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and usually 300 μm or less, preferably 200 μm or less. More preferably, it is 100 μm or less. If it is too small, there is a tendency that light is scattered due to a diffraction phenomenon or that the production becomes difficult. If it is too large, the brightness and darkness of the portion from which light is extracted and the portion from which light is not extracted can be visually recognized, which may cause an optical defect.

The height of the prism 141 (in this embodiment, the dimension in the Z-axis direction; see FIG. 15) h is usually 1.0 μm or more, preferably 2.0 μm or more, more preferably 3.0 μm or more, and usually 500 μm. Hereinafter, it is preferably 400 μm or less, more preferably 300 μm or less. However, the height of the prism 141 is preferably set to be equal to or less than the height of the prism 121 from the viewpoint of preventing light guided in the light guide 103 from spreading in the Y-axis direction.

Incidentally, since the prism 141 is formed so as to overlap the prism 121, the prism 121 is partitioned by the prism 141 on the light extraction surface 120 as shown in FIG. In this case, it is preferable that the prism 121 has an anisotropic shape even when the prism 121 is viewed from the Z-axis direction in each section. In particular, the length Ly of the prism 121 is larger than the width Lx of the prism 121 so that the light guided through the light guide 103 is guided along the X axis direction without spreading in the Y axis direction. It is preferable to do so. Usually, the length Lx of the divided prisms 121 is equal to the interval D of the prisms 141. From the above viewpoint, the interval D of the prisms 141 is preferably larger than the width Ly of the prisms 121.

On the other hand, as shown in FIG. 16, a prism 151 is formed on the back surface 130 of the light guide 103 so as to overlap the prism 131. The prism 151 is a light extraction structure that extracts light guided through the light guide 103 from the light extraction surface 120, and is formed in the same manner as the prism 141 on the light extraction surface 120. That is, the prism 151 is a prism having a triangular cross

section having slopes

152 and 153. In addition, the anisotropic main axis PB of the prism 151 extends in a direction (preferably a direction orthogonal to the main axis PA of the prism 131, see FIG. 17). Furthermore, the prisms 151 are formed side by side with a predetermined interval D between the adjacent prisms 151, and the interval D between the prisms 151 is set to be shorter from the near side to the back side in the X-axis direction. (See FIG. 15).

Since the illuminating device 3 as 3rd embodiment of this invention is comprised as mentioned above, it can be used similarly to the illuminating device 1 which concerns on 1st embodiment, and the same advantage is acquired.
FIG. 18 illustrates a cross section of the light guide 103 taken along a plane perpendicular to the Y-axis direction in order to explain how light guided through the light guide 103 according to the third embodiment of the present invention is extracted. It is sectional drawing which expands and shows typically. As shown in FIG. 18, in the illumination device 3 according to the third embodiment of the present invention, the light 141 is formed with the prism 141 and the prism 151 as the light extraction structure, and thus the light A is emitted from the light extraction surface 120. It can be taken out efficiently.

[Fourth embodiment]
FIG. 19 is a perspective view schematically showing an outline of a lighting apparatus as a fourth embodiment of the present invention. FIG. 20 is a perspective view schematically showing a state where a part of the light guide according to the fourth embodiment of the present invention is cut out and viewed from the light extraction surface side. FIG. 21 is a perspective view schematically showing a state in which a part of the light guide according to the fourth embodiment of the present invention is cut out and viewed from the back surface side. 19 to 21, the same reference numerals as those in FIGS. 1 to 18 indicate the same parts as those in FIGS. 1 to 18.

As shown in FIG. 19, the illuminating device 4 as 4th embodiment of this invention is provided with the plate-shaped light guide 104, the some light source 201, and the light modulation apparatus 301 which light-modulates the light source 201. As shown in FIG. Here, the light source 201 and the light control device 301 are the same as in the first embodiment. Further, the light guide 104 has a fine unevenness 144 in addition to the prism 121 on the light extraction surface 120 which is a part having the prism 121, and is fine in addition to the prism 131 on the back surface 130 which is a part having the prism 131. Except having the unevenness 154, it is the same as the light guide 101 of the first embodiment.

As shown in FIG. 20, the light extraction surface 120 of the light guide 104 has a large number of irregularities 144 so as to overlap the surface of the prism 121. The unevenness 144 is a light extraction structure that extracts light guided through the light guide 104 from the light extraction surface 120. In addition, the unevenness | corrugation 144 should just be one or both of a recessed part and a convex part, and the example which provided the convex part as the unevenness | corrugation 144 in FIG.
There is no limitation on the shape of the unevenness 144, for example, a polygonal cylinder, a cylinder, a polygonal pyramid, a shape lacking the top of the polygonal cone, a cone, a shape lacking the top of the cone, an elliptical cone, a shape lacking the top of the elliptical cone, Or a part of ellipsoid rotary body etc. are mentioned.

The width of the unevenness 144 is usually 1.0 μm or more, preferably 2.0 μm or more, more preferably 3.0 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less.
The height of the unevenness 144 is usually 0.5 μm or more, preferably 1.0 μm or more, more preferably 1.5 μm or more, and usually 25 μm or less, preferably 20 μm or less, more preferably 15 μm or less.

The interval (pitch) between the projections and depressions 144 is set so as to become narrower from the front in the X-axis direction toward the back. Accordingly, the formation density of the unevenness 144 increases as the distance from the light introduction surface 110 increases, and the light can be efficiently extracted by the unevenness 144 as the distance from the light introduction surface 110 increases. Therefore, similarly to the third embodiment, light can be uniformly extracted from the light extraction surface 120 in the X-axis direction.
The specific interval between the irregularities 144 is usually 1.0 μm or more, preferably 2.0 μm or more, more preferably 3.0 μm or more, and is usually 100,000 μm or less, preferably 50000 μm or less, more preferably 30000 μm or less.

On the other hand, as shown in FIG. 21, irregularities 154 are formed on the back surface 130 of the light guide 104 so as to overlap the surface of the prism 131. The unevenness 154 is a light extraction structure that extracts light guided through the light guide 104 from the light extraction surface 120, and is formed in the same manner as the unevenness 144 of the light extraction surface 120.

Since the illuminating device 4 as 4th embodiment of this invention is comprised as mentioned above, it can be used similarly to the illuminating device 1 which concerns on 1st embodiment, and the same advantage is acquired.
Moreover, in the illuminating device 4 according to the fourth embodiment of the present invention, since the unevenness 144 and the unevenness 154 are formed in the light guide 104 as the light extraction structure, light can be efficiently extracted from the light extraction surface 120. .

[Fifth embodiment]
FIG. 22 is a perspective view schematically showing an outline of a lighting apparatus as a fifth embodiment of the present invention. FIG. 23 is a cross-sectional view schematically showing a cross section of the light guide according to the fifth embodiment of the present invention cut along a plane perpendicular to the Y-axis direction. 22 and 23, the same reference numerals as those in FIGS. 1 to 21 denote the same parts as those in FIGS.

As shown in FIG. 22, the illumination device 5 as the fifth embodiment of the present invention includes a plate-shaped light guide 105, a plurality of light sources 201, and a light control device 301 that adjusts the light source 201. Here, the light source 201 and the light control device 301 are the same as in the first embodiment. The light guide 105 is the same as the light guide 101 of the first embodiment, except that the light guide 105 includes the light diffusing agent 145 in its entirety including the portion where the prism 121 and the prism 131 are formed. is there.

23, the light diffusing agent 145 is present in the light guide 105. The light diffusing agent 145 is a particle having a property of diffusing light, and functions as a light extraction structure that extracts light guided through the light guide 105 from the light extraction surface 120.

The types of light diffusing agent 145 can be broadly classified into inorganic fillers and organic fillers. Examples of the inorganic filler include glass, silica, aluminum hydroxide, aluminum oxide, titanium oxide, zinc oxide, barium sulfate, magnesium silicate, and a mixture thereof. Examples of the organic filler include acrylic resin, polyurethane resin, polyvinyl chloride resin, polystyrene resin, polyacrylonitrile resin, polyamide resin, polysiloxane resin, melamine resin, benzoguanamine resin, fluorine resin, polycarbonate resin, silicone resin, polyethylene resin, Examples thereof include an ethylene-vinyl acetate copolymer, acrylonitrile, and a cross-linked product thereof. Among these, as the organic filler, an acrylic resin, a polystyrene resin, a polysiloxane resin, and fine particles made of a crosslinked product thereof are preferable in terms of high dispersibility, high heat resistance, and no coloration (yellowing) during molding. . Among these, fine particles made of a cross-linked product of polysiloxane resin are more preferable in that they have few volatile components during molding. In addition, what consists of 2 or more types of raw materials as a light-diffusion agent 145 may be used, and 2 or more types of light-diffusion agents may be mixed and used.

There is no limitation on the shape of the light diffusing agent 145. For example, a spherical shape, a cubic shape, a needle shape, a rod shape, a spindle shape, a plate shape, a scale shape, a fiber shape, and the like can be given. In addition, the light diffusing agent 145 may be used in one shape or in combination of two or more shapes in an arbitrary ratio.

The diameter of the light diffusing agent 145 is preferably 0.2 μm or more, more preferably 0.5 μm or more, preferably 50 μm or less, more preferably 10 μm or less. In addition, when the light-diffusion agent 145 is not a perfect sphere, the diameter here is substituted by the diameter of a sphere having the same volume. In the case of a filler having a significantly different size in one direction such as a needle shape, a diameter of a circle having the same area as the cross-sectional area of the cross section perpendicular to the direction is substituted.

The concentration of the light diffusing agent 145 is preferably set so as to increase from the near side to the far side in the X-axis direction. Accordingly, the amount of the light diffusing agent 145 increases as the distance from the light introduction surface 110 increases, and the light diffusing agent 145 can efficiently extract light as the distance from the light introduction surface 110 increases. Therefore, similarly to the third and fourth embodiments, light can be extracted uniformly from the light extraction surface 120 in the X-axis direction.
The specific concentration of the light diffusing agent 145 can be set according to the thickness of the light guide 105 or the like. The content of the light diffusing agent 145 in the entire light guide 105 is preferably 0.0001% by weight or more, more preferably 0.0005% by weight or more, preferably 0.1% by weight or less, more preferably 0. 0.05% by weight or less. If the amount is too small, there is a possibility that light cannot be extracted. If the amount is too large, light is emitted too much at the front position and the brightness uniformity tends to decrease.

Since the illuminating device 5 as the fifth embodiment of the present invention is configured as described above, it can be used similarly to the illuminating device 1 according to the first embodiment, and the same advantages can be obtained.
Moreover, in the illuminating device 5 which concerns on 5th embodiment of this invention, since the light diffusing agent 145 is included in the light guide 105 as a light extraction structure, light can be efficiently extracted from the light extraction surface 120.

[Sixth embodiment]
FIG. 24 is a perspective view schematically showing an outline of a lighting apparatus as a sixth embodiment of the present invention. 24, the same reference numerals as those in FIGS. 1 to 23 denote the same parts as those in FIGS.
As shown in FIG. 24, the illuminating device 6 as 6th embodiment of this invention is equipped with the plate-shaped light guide 106, the some light source 201, and the light modulation apparatus 301 which light-modulates the light source 201. As shown in FIG. Here, the light source 201 and the light control device 301 are the same as in the first embodiment. The light guide 106 has a lenticular 126 instead of the prism 121 as the concavo-convex structure A on the light extraction surface 120 and a lenticular 136 instead of the prism 131 as the concavo-convex structure A on the back surface 130. It is the same as the light guide 101 of the embodiment.

FIG. 25 is a perspective view schematically showing a state in which a part of the light guide body 106 according to the sixth embodiment of the present invention is cut out and viewed from the light extraction surface 120 side. FIG. 26 is a perspective view schematically showing a state in which a part of the light guide body 106 according to the sixth embodiment of the present invention is cut out and viewed from the back surface 130 side. Further, FIG. 27 illustrates the light guide 106 cut along a plane perpendicular to the X-axis direction in order to explain the internal reflection of the light guided through the light guide 106 according to the sixth embodiment of the present invention. It is sectional drawing which expands and shows the cross section typically. 25 to 27, the same reference numerals as those in FIGS. 1 to 24 denote the same parts as those in FIGS.

25 and 26, the lenticular 126 and the lenticular 136 are the same as the prism 121 and the prism 131, respectively, except for the cross-sectional shape. A cross section obtained by cutting the lenticular 126 and the lenticular 136 along a plane perpendicular to the X-axis direction has a curved shape such as a partial shape of a circle or an ellipse (for example, a semicircular shape or a semielliptical shape), as shown in FIG. ing. Accordingly, the

surfaces

127 and 137 of the lenticular 126 and the lenticular 136 are formed with smooth curved surfaces, and gradually incline with respect to the light extraction surface 120 from the center to the end in the Y-axis direction. Since the surface 127 of the lenticular 126 and the surface 137 of the lenticular 136 are inclined as described above, the surface 127 and the surface 137 each have a portion that is not parallel to the Y-axis direction (that is, intersects with the Y-axis). Therefore, the light guide 101 is guided by the surface 127 of the lenticular 126 and the surface 137 of the lenticular 136 as well as the

inclined surfaces

122 and 123 of the prism 121 and the

inclined surfaces

132 and 133 of the prism 131 in the first embodiment. The light A can be internally reflected so as not to spread in the Y-axis direction.

Since the illumination device 6 as the sixth embodiment of the present invention is configured as described above, it can be used in the same manner as the illumination device 1 according to the first embodiment, and the same advantages can be obtained.

[Seventh embodiment]
FIG. 28 is a perspective view schematically showing an outline of a liquid crystal display device as a seventh embodiment of the present invention. In FIG. 28, the same reference numerals as in FIGS. 1 to 27 denote the same parts as in FIGS. As shown in FIG. 28, a liquid crystal display device 7 as a seventh embodiment of the present invention includes a lighting device 1 and a liquid crystal panel 401.

As the liquid crystal panel 401, liquid crystal panels of various known display modes can be used. For example, twisted nematic (TN) mode, super twisted nematic (STN) mode, hybrid alignment nematic (HAN) mode, vertical alignment (VA) mode, multi-domain vertical alignment (MVA) mode, in-plane switching (IPS) mode, optical A liquid crystal panel with a display mode such as a curry-compensated birefringence (OCB) mode can be employed. In the liquid crystal panel 401, an image can be displayed on the display surface 410 by light supplied to the side opposite to the display surface 410 (that is, the back side).

The lighting device 1 is the same as the device described in the first embodiment. The illumination device 1 is provided on the back side of the liquid crystal panel 401 and irradiates the liquid crystal panel 401 with light.

Since the liquid crystal display device 7 as the seventh embodiment of the present invention is configured as described above, light is irradiated from the illumination device 1 to the liquid crystal panel 401 when in use. At this time, since the light guide 101 can selectively extract light from the light extraction surface 120 in a desired region, the lighting device 1 can selectively irradiate the desired region of the liquid crystal panel 401 with light. it can. Therefore, in the liquid crystal display device 7 as the seventh embodiment, efficient local dimming can be realized, and advantages such as improved image quality and energy saving can be obtained.

[Other Embodiments]
The first embodiment to the seventh embodiment of the present invention have been described in detail above. However, the present invention may be further modified.
For example, the configurations of the above-described embodiments may be implemented in any combination.

For example, regarding the shapes of the light guides 101 to 106, the light guides 101 to 106 may have a shape other than a plate shape. Therefore, the light extraction surface 120 and the back surface 130 are not necessarily parallel. Even when the light guides 101 to 106 are plate-shaped, the shape of the main surface may not be rectangular. Further, the thicknesses of the light guides 101 to 106 may be nonuniform if necessary.

For example, for the light introduction surface 110, the light introduction surface 110 may not be a surface orthogonal to the X-axis direction. Further, the light introduction surface 110 may be not only one surface but also two or more surfaces. Taking the illumination device 8 as a modification to the first embodiment as an example, as shown in FIG. 29, the side surface 140 on the opposite side of the light introduction surface 110 of the light guide body 101 is also a light introduction surface, and the front surface of the side surface 140. Alternatively, the light source 201 may be provided. FIG. 29 is a diagram schematically showing a lighting device 8 as a modification of the first embodiment, and the same reference numerals as in FIGS. 1 to 28 indicate the same parts as in FIGS.

For example, regarding the concavo-convex structure A, the cross-sectional shapes of the

prisms

121 and 131 may be shapes other than the triangle and the trapezoid. For example, it may be a quadrangle other than a trapezoid, or may be a pentagon or more polygon.
Further, the direction of the principal axis of the anisotropic shape (

prisms

121 and 131 and lenticulars 126 and 136) of the concavo-convex structure A intersects the predetermined direction unless the direction is perpendicular to the predetermined direction in which light is guided. It may be a direction. Therefore, when the concavo-convex structure A is a bowl-shaped convex part, the extending direction can be set to any direction as long as it is not a direction orthogonal to the predetermined direction. However, it is preferable that the intersection angle between the anisotropic main axis of the concavo-convex structure A and the predetermined direction is small.

Further, when the concavo-convex structure A has the

flat portions

125 and 135, the positions thereof are arbitrary. Taking a modification to the third embodiment as an example, a flat portion 125 may be provided in the recess 124 as shown in FIG. Furthermore, the flat portion 125 may be provided on both the convex portion and the concave portion 124 of the prism 121 or the like. 30 is a perspective view schematically showing a state in which a part of the light guide 107 as a modified example of the third embodiment is cut out and viewed from the light extraction surface 120 side. Like reference numerals denote like parts as in FIGS.

Further, the concavo-convex structure A may be a structure other than the ridge-shaped convex portions such as the

prisms

121 and 131 and the

lenticulars

126 and 136. A specific example will be described with reference to the drawings.
FIG. 31 is a perspective view schematically showing a state in which a part of the light guide 108 according to the embodiment of the present invention is cut out and viewed from the light extraction surface 120 side. FIG. 32 is a view of one of the concavo-convex structures A formed on the light extraction surface 120 of the light guide 108 according to an embodiment of the present invention, as viewed from the light extraction surface side in the Z-axis direction. is there. 31 and 32, the same reference numerals as those in FIGS. 1 to 30 denote the same parts as those in FIGS.
As shown in FIG. 31, the concavo-convex structure A may be a convex portion 128 having a shape of a part of an ellipsoid. Such a convex portion 128 is also a surface in which at least a part of the surface 129 is not parallel to the Y-axis direction (that is, intersects with the Y-axis). Therefore, similarly to the

slopes

122 and 123 of the prism 121 and the

slopes

132 and 133 of the prism 131 in the first embodiment, the light guided in the light guide 101 is also guided in the Y-axis direction by the surface 129 of the convex portion 128. Can be internally reflected so as not to spread.
Further, as shown in FIG. 32, when viewed from the Z-axis direction, the convex portion 128 has an anisotropic shape. Specifically, the length (here, the dimension in the X-axis direction) Lx of the convex portion 128 is larger than the width (here, the dimension in the Y-axis direction) Ly of the convex portion 128. As a result, among the internal reflections on the surface 129 of the convex portion 128, the frequency of internal reflection that reverses the direction of the Y-axis direction component of light is increased, and the above-described effect of suppressing the spread of light in the Y-axis direction is effective. Can be demonstrated.

In addition, the concavo-convex structure A is not necessarily formed on at least one of the light extraction surface 120 and the back surface 130 as long as it is formed on both surfaces.
Moreover, although the uneven structure A may employ | adopt the same structure by the light extraction surface 120 and the back surface 130 like embodiment mentioned above, you may employ | adopt a different structure.
In addition, the concavo-convex structure A may be provided with only one type of structure within the light extraction surface 120 and the back surface 130 as in the above-described embodiment, but two or more types of structures are combined within the same surface. You may do it.
Further, the concavo-convex structure A need not be provided on the light extraction surface 120 or the back surface 130 in all the regions 101a to 101h of the light guide 101. Therefore, if the light extraction surface 120 or the back surface 130 is provided in at least the desired regions 101a to 101h from which light is to be extracted, the concavo-convex structure A is provided only on a part of the light extraction surface 120 and the back surface 130. Also good.

For example, regarding the light extraction structure, a lenticular may be used as a bowl-shaped unevenness as the light extraction structure. Even when a lenticular is used as the light extraction structure, advantages similar to those obtained when the prism 141 is used (see the third embodiment) can be obtained. At this time, the interval, width, height, extending direction, etc. of the lenticular can be the same as those of the prism 141.

Further, if the light extraction structure is formed on one of the light extraction surface 120 and the back surface 130, it does not necessarily have to be formed on both.
Further, as the light extraction structure, the same structure may be adopted for the light extraction surface 120 and the back surface 130 as in the above-described embodiment, but different structures may be adopted.
In addition, as for the light extraction structure, only one type of structure may be provided within the surfaces of the light extraction surface 120 and the back surface 130 as in the above-described embodiment, but two or more types of structures are combined within the same surface. You may do it.
The light extraction structure may be configured such that the density increases as the distance from the light introduction surface 110 increases as in the above-described embodiment, but the size of the light extraction structure increases as the distance from the light introduction surface 110 increases. However, light can be extracted uniformly from the light extraction surface 120 in the X-axis direction.

For example, with regard to the light source 201, in the above-described embodiment, the light source 201 is individually dimmed by the dimming device 301, but may be dimmed for each group. In this case, for example, a group of two or more light sources 201 is set corresponding to each of the regions 101a to 101h of the light guide 101, and the group of light sources 201 corresponding to the desired regions 101a to 101h from which light is to be extracted. The light source 201 can be dimmed to emit light.

For example, regarding the liquid crystal display device 7, the illumination device combined with the liquid crystal panel 401 is not limited to the illumination device 1 according to the first embodiment.
Further, the liquid crystal display device 7 may be provided with components other than the liquid crystal panel 401 and the lighting device 1. Examples of the component include a brightness enhancement film, a light collecting film, a prism sheet, a light diffusion plate, an optical compensation film, a diffusion sheet, and a reflection sheet.

[Light guide material and manufacturing method]
Hereinafter, the material and manufacturing method of the light guide will be described.
Examples of the material for the light guide include glass and transparent resin. In addition, the material of a light guide may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

Examples of the transparent resin include propylene-ethylene copolymer, polystyrene, (meth) acrylic acid ester-aromatic vinyl compound copolymer, polyethylene terephthalate, terephthalic acid-ethylene glycol-cyclohexanedimethanol copolymer, polycarbonate. , Methacrylic resin, and resin having an alicyclic structure (for example, norbornene-based resin). Among these, resins having an alicyclic structure, methacrylic resins, and (meth) acrylic acid ester-aromatic vinyl compound copolymer resins are preferable, and resins having an alicyclic structure are particularly preferable.

A resin having an alicyclic structure has good fluidity of the molten resin. Therefore, for example, when a light guide is manufactured by injection molding, the mold cavity can be filled with a low injection pressure, and a weld line is hardly generated. For example, when manufacturing a light guide by extrusion molding, there is little thickness unevenness at the time of molding, and shape formation after molding is easy. Furthermore, since the resin having an alicyclic structure has extremely low hygroscopicity, it has excellent dimensional stability and is less likely to warp the light guide. Furthermore, since the specific gravity of the resin having an alicyclic structure is small, the light guide can be reduced in weight.

Examples of the resin having an alicyclic structure include polymer resins having an alicyclic structure in the main chain or side chain. Among them, a polymer resin having an alicyclic structure in the main chain is particularly suitable because it has good mechanical strength and heat resistance.
The alicyclic structure is preferably a saturated cyclic hydrocarbon structure.
The number of carbon atoms constituting the alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, and particularly preferably 15 or less.
The ratio of the repeating unit having an alicyclic structure in the polymer resin having an alicyclic structure is preferably 50% by weight or more, more preferably 70% by weight or more, and 90% by weight or more. More preferably.

Examples of the resin having an alicyclic structure include a ring-opening polymer or a ring-opening copolymer of a norbornene monomer or a hydrogenated product thereof; an addition polymer or an addition copolymer of a norbornene monomer; Polymers of monocyclic olefin monomers or their hydrogenated products; Polymers of cyclic conjugated diene monomers or their hydrogenated products; Vinyl alicyclic hydrocarbon monomers Or a hydrogenated product thereof; a polymer of a vinyl aromatic hydrocarbon monomer or a hydrogenated product of an unsaturated bond part containing an aromatic ring of the copolymer; and the like. Among these, hydrogenated products of norbornene-based monomer polymers and hydrogenated products of unsaturated bonds including aromatic rings of vinyl aromatic hydrocarbon-based monomer polymers have mechanical strength and heat resistance. It is particularly suitable because of its excellent properties.

Furthermore, among the above transparent resins, methacrylic resins are excellent in transparency, strong and resistant to cracking, and therefore can be suitably used. Examples of the methacrylic resin include a methacrylic resin molding material containing 80% or more of a methyl methacrylate polymer defined in JIS K6717. Among the methacrylic resins specified in this standard, methacrylic resins having a specified classification code 100-120 having a Vicat softening point temperature of 96 to 100 ° C. and a melt flow rate of 8 to 16 have appropriate fluidity and strength. Is preferred.

The molding material for the light guide may contain an antioxidant in order to prevent oxidative degradation and thermal degradation during molding. Examples of the antioxidant include a phenolic antioxidant, a phosphorus antioxidant, and a sulfur antioxidant. Of these, phenolic antioxidants are preferred, and alkyl-substituted antioxidants are particularly preferred. In addition, an antioxidant may be used individually by 1 type and may be used combining two or more types by arbitrary ratios. The amount of the antioxidant is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, preferably 2 parts by weight or less, more preferably 1 part by weight with respect to 100 parts by weight of the resin component. It is as follows.

In the molding material for the light guide, a light stabilizer may be included in order to improve the light resistance of the light guide. Examples of the light resistance stabilizer include hindered amine light resistance stabilizer (HALS) and benzoate light resistance stabilizer. Among these, hindered amine light resistance stabilizers are preferred. In addition, a light-resistant stabilizer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. The amount of the light-resistant stabilizer is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, particularly preferably 0.05 parts by weight or more, preferably 2 parts by weight with respect to 100 parts by weight of the resin component. The amount is not more than parts by weight, more preferably not more than 1 part by weight, particularly preferably not more than 0.5 parts by weight.

The light guide body may further contain other additives as required. Examples of other additives include stabilizers such as heat stabilizers, ultraviolet absorbers, and near infrared absorbers; resin modifiers such as lubricants and plasticizers; colorants such as dyes and pigments; antistatic agents, and fluorescence. Examples include brighteners and light diffusing agents. In addition, another additive may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

The dimensions of the main surface of the light guide (in the above embodiment, the dimensions in the X-axis direction and the Y-axis direction) usually depend on the size of the effective surface of the liquid crystal panel of the liquid crystal display device in which the light guide is used. Is set. Further, when the thickness of the light guide (in the above embodiment, the dimension in the Z-axis direction) is smaller than the height of the light-emitting portion of the light source (in the above-described embodiment, the dimension in the Z-axis direction), the liquid crystal From the viewpoint of thinning and weight reduction of the panel, a large value is preferable from the viewpoint that light from the light source can be easily taken into the light guide. Especially, since the thickness of the light guide can be easily manufactured and handled, it is preferably 0.02 mm or more, more preferably 0.1 mm or more, and thinning and weight reduction can be realized. It is preferably 5 mm or less, more preferably 4 mm or less, and particularly preferably 3 mm or less.

As the light guide, for example, one having a refractive index of 1.533 (critical angle 40.7 °) can be used.

When the light guide is made of resin, there is a possibility that the light guide will undergo dimensional changes (elongation or warpage) due to moisture absorption. In particular, when the size of the light guide is large (for example, 40 inches), the relative positional relationship between the light source and the light introduction surface changes in the lighting device due to the change in size, and the light utilization efficiency tends to decrease. For this reason, the water absorption rate of the light guide is preferably set to 0.50% or less, more preferably 0.25% or less, and even more preferably 0.05% or less. The water absorption rate in the present specification is determined according to JIS K7209 A method after drying a test piece having a thickness of 3 mm and a disk shape having a diameter of 50 mm or a square having a side of 50 mm at 50 ° C. for 24 hours. It can be determined from the increase in weight when it is allowed to cool in a filter and immersed in water at 23 ° C. for 24 hours.

Although there is no restriction | limiting in the manufacturing method of a light guide, For example, when forming a light guide with resin, it can manufacture by the injection molding method, the extrusion molding method, and the casting method.

Also, there is no particular limitation on the method for forming the uneven structure on the surface of the light guide. For example, a flat light guide may be prepared in advance, and a concavo-convex structure may be formed later on the surface of the light guide. In this case, as a method for forming the concavo-convex structure on the surface of the flat light guide, for example, a method by cutting using a tool capable of forming a concavo-convex structure of a desired shape, a desired method by applying a photo-curing resin A method of curing the transferred shape mold, a method of applying dot printing by screen printing, a method of forming a concavo-convex structure by laser processing, and forming a concavo-convex structure by applying a photo-curing resin or a thermosetting resin by an inkjet method. Method, etc.

As a method for forming the uneven structure on the surface of the light guide, for example, the uneven structure may be formed simultaneously with the formation of the light guide. In this case, for example, profile extrusion can be performed using a profile die having a shape corresponding to a desired uneven structure. Further, for example, prism rows may be formed by embossing after extrusion. Further, for example, a casting mold capable of forming a desired concavo-convex shape is prepared, and a light guide is produced by casting using this casting mold, and the concavo-convex structure is formed simultaneously with the formation of the light guide. . Moreover, when producing a light guide by injection molding and simultaneously forming a concavo-convex structure, a mold capable of forming a desired concavo-convex structure may be used.

In addition, the mold used for the mold shape transfer to the photo-curing resin, the extrusion process using a deformed die, the embossing, the casting, or the injection molding is a metal member of a mold using a tool capable of forming a desired concavo-convex structure, for example. It can be obtained by cutting or forming on a member on which a desired shape is formed.

〔light source〕
Hereinafter, the light source will be described.
Examples of the light source include a point light source such as an LED and a laser diode, and a line light source such as a cold cathode tube (CCFL, EEFL) and a hot cathode tube (HCFL), and a point light source is preferably used. Any point light source may be used as long as it can at least turn on / off and control the amount of emitted light with desired responsiveness. For example, a semiconductor laser may be used. However, it is usually preferable to use an LED as described in the above embodiment. Examples of the LED include a blue-yellow pseudo white light emitting diode, a three-color (RGB) type white light emitting diode, and the like.

As the LED, for example, a side-emitting LED, a surface-mounted LED, or a bullet-type LED is used. The dimension of the light emitting part of the LED can be set according to the light distribution characteristic of the LED. Usually, the width and height of the light emitting part of the LED are made equal. However, when the LED has an elliptical or oval cross section, the LED having a different width and height may be used. Good.

A general high dome type LED has a Lambertian light distribution and emits a relatively large divergent light having a half-value angle (full-width at half maximum) of about 120 °. However, from the viewpoint of suppressing the spread of light, the LED has a full width at half maximum of preferably 80 ° or less, more preferably 70 ° or less, and particularly preferably 60 ° or less. Ideally, LEDs that emit as close to parallel light as possible are preferred. Further, from the viewpoint of suppressing darkening of the portion corresponding to the LEDs in the front portion of the light guide, the full width at half maximum of the LED is preferably 90 ° or more, more preferably 100 ° or more, and 110 ° or more. Particularly preferred.

In addition, as a light source, you may use combining light emitting elements, such as LED, and optical elements, such as a lens. For example, even when an LED having a wide full width at half maximum is used, a light source that emits light at a full width at half maximum within the above-described preferable range can be realized by combining the LED and the lens. Alternatively, a light source capable of turning on / off and adjusting the amount of light may be combined by combining a light source that always emits light and an optical shutter (for example, a liquid crystal panel) provided between the light source and the light introduction surface.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples, and may be arbitrarily set within the scope of the claims of the present invention and its equivalents. You can change it to

[Example 1]
FIG. 33 is a diagram for explaining simulation conditions set in the simulation performed in the first embodiment. In the following examples, an optical model was created and simulated under the conditions described later using optical simulation software “LightTools” (manufactured by Cybernet Co., Ltd.). In addition, as a material of the light guide, a thermoplastic alicyclic structure-containing resin (trade name: ZEONOR1420, manufactured by Nippon Zeon Co., Ltd., refractive index: 1.533, critical angle: 40.7 °, water absorption: 0.01%) was used. It was set as a thing.

The light guide was a rectangular flat light guide having a long side of 700 mm, a short side of 250 mm, and a thickness of 2 mm.
As shown in FIG. 2, an uneven structure A is provided on the entire surface of the light extraction surface corresponding to one main surface of the light guide so as to have a prism extending along the short side direction of the light guide. . In the prism of this light extraction surface, the shape of the cross section cut by a plane perpendicular to the short side direction is an isosceles triangle, and the apex angle of the isosceles triangle of the cross section is 60 °. The height of the prism on the light extraction surface was 50 μm and the width was 57.7 μm.
Further, as shown in FIG. 4, the entire surface of the back surface corresponding to the other main surface of the light guide has a concavo-convex structure A having a prism extending along the short side direction of the light guide. . The prism on the back surface has an isosceles triangle shape in a cross section cut by a plane perpendicular to the short side direction, and the apex angle of the isosceles triangle of the cross section is 90 °. The height of the prism on the back surface was 50 μm and the width was 100 μm.

The light source was an LED having an outer diameter of 2.5 mm long side, 1.5 mm short side, and 0.5 mm thickness. Moreover, the dimension of the light emission part of LED was made into 2 mm of long sides, and 1 mm of short sides. Further, the absorption of the light emitting part of the LED was 15%, and the full width at half maximum was 120 °.

As shown in FIG. 33, an LED 503 is provided at the center in the long-side direction Y of the light introduction surface 502, which is one of the long sides of the light guide body 501, and the light A is irradiated from the LED 503 to the light introduction surface 502 of the light guide body 501. I was able to do it. At this time, the distance between the LED 503 and the light introduction surface 502 of the light guide 501 was 2 mm. The periphery of the LED 503 is covered with a lamp cover (model E6SL lamp cover set in the software used) 504. Further, the light irradiation from the LED 503 is such that the axis of the light is parallel to the short side direction X of the light guide body 501, and the predetermined direction in which the light is guided is parallel to the short side direction X.

When light is emitted from the LED 503 in the above-described configuration, the measurement position immediately inside the side surface 505 opposite to the light introduction surface 502 (that is, the light guide that is 250 mm away from the light introduction surface 502 along the short side direction X). The light is detected on a surface in the direction 501 and parallel to the light introduction surface 502. From the detected light, the intensity of the light integrated at the measurement position at the measurement position intersecting the line extending perpendicularly from the center of the LED 503 to the light introduction surface 502 in the Z-axis direction is 100%. and when the width W ₅₀ of the light intensity of the light in the long-side direction Y to be 50% _spread, measure the width W ₅ of the spread of light in the longitudinal direction Y in which the intensity of light of 5% did. The results are shown in Table 1.

Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35. 34 and 35, the horizontal axis represents the inclination angle of the inclined surface of the prism on the back surface. The inclination angle of the prism of the light extraction surface is plotted with a “cross mark” when the inclination angle is 60 °, and plotted with a “black circle mark” when the inclination angle is 35 °. Plots with an inclination of 30 ° are plotted with “black triangles”, those with an inclination of 25 ° are plotted with “black squares”, and those with an inclination of 20 ° are plotted with “X” When the angle of inclination is 15 °, it is plotted with “white circles”. When the angle of inclination is 10 °, it is plotted with “white triangles”. Plotted with “white squares”.

[Example 2]
The prism setting on the light extraction surface of the light guide 501 is changed, except that the apex angle of the isosceles triangle in the section of the prism is 110 °, the height of the prism is 50 μm, and the width is 142.8 μm. In the same manner as in Example 1, the light spread widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 3
The prism setting on the light extraction surface of the light guide 501 is changed, except that the apex angle of the isosceles triangle of the section of the prism is 120 °, the prism height is 50 μm, and the width is 173.2 μm. In the same manner as in Example 1, the light spread widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 4
Other than changing the prism setting of the light extraction surface of the light guide 501, the apex angle of the isosceles triangle of the section of the prism is 140 °, the prism height is 50 μm, and the width is 274.7 μm. In the same manner as in Example 1, the light spread widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 5
The light spreading widths W ₅₀ and W ₅ were measured in the same manner as in Example 4 except that the prism on the back surface of the light guide 501 was changed to lenticular. The cross-sectional shape of the lenticular cut by a plane perpendicular to the short side direction X of the light guide 501 was a semicircle, the height of the lenticular was 50 μm, and the width was 100 μm. The results are shown in Table 1.

Example 6
Example 4 except that the light extraction surface of the light guide 501 has a prism as the concavo-convex structure B as shown in FIG. 13 in addition to the prism as the concavo-convex structure A as in Example 4. Similarly, light spreading widths W ₅₀ and W ₅ were measured.
The prism as the concavo-convex structure B is a prism extending along the long-side direction Y of the light guide 501, and the shape of the cross section taken along a plane perpendicular to the long-side direction Y of the light guide 501 is an isosceles triangle It was. Further, the apex angle of the isosceles triangle of the cross section was 150 ° and the height was 50 μm. Further, the interval D (see FIG. 15) between the prisms of the concavo-convex structure B was set to a gradation. Specifically, as shown in FIG. 33, in region I where the distance from the light introduction surface 502 is 0 mm to 9.6 mm, D = 2400 μm and the distance from the light introduction surface 502 is 9.6 mm to 34.8 mm. In the region II, D = 1800 μm, and in the region III where the distance from the light introduction surface 502 is 34.8 mm to 94.8 mm, D = 1200 μm and the distance from the light introduction surface 502 is 94.8 mm to 249.6 mm. Then, D = 600 μm.

Further, in Example 6, the light extracted from the light extraction surface at a measurement position 250 mm away from the light introduction surface 502 along the short side direction X also in the long side direction Y where the light intensity is 50% or more. The width of the light spread was measured. The results are shown in Table 1.

Example 7
In the same manner as in Example 1 except that the setting of the prism on the back surface of the light guide 501 is changed, the apex angle of the isosceles triangle in the cross section of the prism is 120 °, and the width is 173.2 μm. The spreading widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 8
In the same manner as in Example 2 except that the setting of the prism on the back surface of the light guide 501 is changed, the apex angle of the isosceles triangle in the cross section of the prism is 120 °, and the width is 173.2 μm. The spreading widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 9
In the same manner as in Example 3 except that the setting of the prism on the back surface of the light guide 501 is changed, the apex angle of the isosceles triangle of the cross section of the prism is 120 °, and the width is 173.2 μm. The spreading widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 10
In the same manner as in Example 4 except that the setting of the prism on the back surface of the light guide 501 is changed, the apex angle of the isosceles triangle of the cross section of the prism is 120 °, and the width is 173.2 μm. The spreading widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 11
Other than changing the settings of the prisms on the light extraction surface and the back surface of the light guide 501 so that the apex angle of the isosceles triangles of the cross sections of both the light extraction surface and the back surface is 130 ° and the width is 214.5 μm in the same manner as in example 1, it was measured width W ₅₀ and W ₅ for the spread of light. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 12
Other than changing the settings of the prisms on the light extraction surface and the back surface of the light guide 501 so that the apex angle of the isosceles triangles of the cross sections of the prisms on both the light extraction surface and the back surface is 140 ° and the width is 274.7 μm in the same manner as in example 1, it was measured width W ₅₀ and W ₅ for the spread of light. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 13
In the same manner as in Example 1 except that the setting of the prism on the back surface of the light guide 501 is changed, the apex angle of the isosceles triangle of the cross section of the prism is 150 °, and the width is 373.2 μm. The spreading widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 14
In the same manner as in Example 2 except that the setting of the prism on the back surface of the light guide 501 is changed, the apex angle of the isosceles triangle of the cross section of the prism is 150 °, and the width is 373.2 μm. The spreading widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 15
In the same manner as in Example 3 except that the setting of the prism on the back surface of the light guide 501 is changed, the apex angle of the isosceles triangle of the cross section of the prism is 150 °, and the width is 373.2 μm. The spreading widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 16
In the same manner as in Example 4 except that the setting of the prism on the back surface of the light guide 501 is changed, the apex angle of the isosceles triangle of the cross section of the prism is 150 °, and the width is 373.2 μm. The spreading widths W ₅₀ and W ₅ were measured. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 17
Other than changing the prism settings of the light extraction surface and the back surface of the light guide 501 so that the apex angle of the isosceles triangles of the cross sections of both the light extraction surface and the back surface is 150 ° and the width is 373.2 μm in the same manner as in example 1, it was measured width W ₅₀ and W ₅ for the spread of light. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 18
Other than changing the setting of the prisms on the light extraction surface and the back surface of the light guide 501 so that the apex angle of the isosceles triangles of the cross sections of the prisms on both the light extraction surface and the back surface is 160 ° and the width is 567.1 μm in the same manner as in example 1, it was measured width W ₅₀ and W ₅ for the spread of light. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 19
The light extraction surface of the light guide 501 was a flat surface without unevenness. Further, the setting of the prism on the back surface was changed so that the apex angle of the isosceles triangle in the cross section of the prism was 30 °, the height of the prism was 50 μm, and the width was 26.8 μm. Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 1. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 20
The light extraction surface of the light guide 501 was a flat surface without unevenness. Also, the setting of the prism on the back surface was changed so that the apex angle of the isosceles triangle in the cross section of the prism was 60 °, the height of the prism was 50 μm, and the width was 57.7 μm. Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 1. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 21
The light extraction surface of the light guide 501 was a flat surface without unevenness. Also, the setting of the prism on the back surface was changed so that the apex angle of the isosceles triangle in the cross section of the prism was 90 °, the height of the prism was 50 μm, and the width was 100.0 μm. Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 1. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

[Example 22]
The light extraction surface of the light guide 501 was a flat surface without unevenness. Also, the setting of the prism on the back surface was changed so that the apex angle of the isosceles triangle in the cross section of the prism was 120 °, the height of the prism was 50 μm, and the width was 173.2 μm. Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 1. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 23
The light extraction surface of the light guide 501 was a flat surface without unevenness. In addition, the setting of the prism on the back surface was changed so that the apex angle of the isosceles triangle in the cross section of the prism was 150 °, the height of the prism was 50 μm, and the width was 373.2 μm. Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 1. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

Example 24
Except that the light output surface of the light guide 501 has a flat surface with no unevenness in the same manner as in Example 5 was measured width W ₅₀ and W ₅ for the spread of light. The results are shown in Table 1.

Example 25
The light extraction surface of the light guide 501 was a flat surface without unevenness. In addition, the setting of the prism on the back surface is changed so that the apex angle of the isosceles triangle of the section of the prism is 90 °, the height of the prism is 50 μm, the width is 100.0 μm, and a flat portion is formed in the concave portion of each prism. A width of 10 μm was provided (see FIG. 30). Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 26
The light extraction surface of the light guide 501 was a flat surface without unevenness. Further, the setting of the lenticular on the back surface was changed, and the cross-sectional shape of the lenticular cut by a plane perpendicular to the short side direction X of the light guide 501 was a semicircle, the height of the lenticular was 50 μm, and the width was 100 μm. And a flat portion having a width of 10 μm was provided between the lenticulars. Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 5. The results are shown in Table 1.

Example 27
The light extraction surface of the light guide 501 was a flat surface without unevenness. Also, the setting of the lenticular on the back surface was changed, and the cross-sectional shape of the lenticular cut along a plane perpendicular to the short side direction X of the light guide 501 was an arc shape obtained by cutting a circle with a radius of 51 μm, and its height was 38 μm. The width was 100 μm. Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 5. The results are shown in Table 1.

Example 28
The light extraction surface of the light guide 501 was a flat surface without unevenness. Also, the setting of the lenticular on the back surface was changed, and the cross-sectional shape of the lenticular cut along a plane perpendicular to the short side direction X of the light guide 501 was an arc shape obtained by cutting a circle with a radius of 51 μm, and its height was 38 μm. The width was 100 μm, and a flat portion was provided between each lenticular with a width of 10 μm. Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 5. The results are shown in Table 1.

Example 29
The prism setting on the back surface of the light guide 501 is changed so that the apex angle of the isosceles triangle of the cross section of the prism is 90 °, the height of the prism is 50 μm, the width is 100.0 μm, and the concave portion of each prism is A flat portion was provided at 10 μm. Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 4. The results are shown in Table 1.

Example 30
The setting of the lenticular on the back surface of the light guide 501 was changed, and the cross-sectional shape of the lenticular cut along a plane perpendicular to the short side direction X of the light guide 501 was an arcuate shape obtained by cutting a circle with a radius of 51 μm. The thickness was 38 μm, the width was 100 μm, and a flat portion was provided between each lenticular with a width of 10 μm. Except for the above items, the light spread widths W ₅₀ and W ₅ were measured in the same manner as in Example 5. The results are shown in Table 1.

[Comparative Example 1]
Except that the light output surface and the back surface of the light guide 501 has a flat surface with no unevenness in the same manner as in Example 1, was measured width W ₅₀ and W ₅ for the spread of light. The results are shown in Table 1. Further, the inclination angle of the inclined surface is calculated from the apex angle of the prism on each of the light extraction surface and the back surface, and the relationship between the inclination angle and the light spread width W ₅₀ is shown in FIG. the relationship between the width W ₅ of the spread of the light shown in FIG. 35.

〔Consideration〕
From Table 1, it can be seen that W ₅₀ is narrower in the example than in the comparative example. Therefore, according to these examples, it can be confirmed that the light guide of the present invention can guide light in a desired light guide direction and can suppress the spread of the light guided.
In particular, the results of Example 6 show that the distribution of light extracted from the light extraction surface falls within a narrow range. Therefore, according to the light guide of this invention, it turns out that light can be selectively extracted from the light extraction surface in a desired area | region.
34 and 35, it can be confirmed that there is a suitable range for the inclination angle of the slope of the prism as the concavo-convex structure A. FIG.
Further, from the results of Examples 24, 26, 27 and 28, it can be confirmed that the lenticular is also suitable.
Further, from the results of Examples 4, 5, 21, and 24 and Examples 25 to 30, it is possible to obtain substantially the same suppression effect even if a flat portion is provided between the concavo-convex structures in order to increase productivity. I understand that.
Further, from the results of Examples 1 to 18 and 25 to 28 and Examples 19 to 24, 29 and 30, it is more W5 when the concave and convex structure is provided on both the light extraction surface and the back surface than when it is attached to one surface. It turns out that becomes narrow. Therefore, according to these embodiments, the light guide of the present invention can guide light more in a desired light guide direction by providing concave and convex structures on both the light extraction surface and the back surface, and more It can be confirmed that the spread of the guided light can be suppressed.
From the results of the above embodiments, it can be understood that according to the present invention, an illumination device and a liquid crystal display device capable of local dimming can be realized.

The light guide of the present invention can be arbitrarily applied to optical applications, and is particularly suitable for a lighting device capable of surface emission. Such an illuminating device is suitable for use in a liquid crystal display device. Further, the lighting device of the present invention can be used for purposes other than the backlight of a liquid crystal display device, for example, as lighting for a show window or the like.

1 to 6, 8 Illumination device 7 Liquid crystal display device 101 to 08 Light guide 110 Light introduction surface 120 Light extraction surface 121,131 Prism (concave / convex structure A, bowl-shaped convex portion)
122, 123, 132, 133 Inclined surfaces of

prisms

124, 134 Concavities between

prisms

125, 135

Flat portions

126, 136 Lenticular (concave structure A, bowl-shaped convex portions)
127,137 Surface of lenticular 128 Convex part (concavo-convex structure A)
129 Surface of convex portion 130 Back surface 140 Side surface of

light guide

141, 151 Prism (light extraction structure, uneven structure B)
142, 143, 152, 153

Prism slope

144, 154 Concavity and convexity (light extraction structure)
145 Light diffusing agent (light extraction structure)
201 light source 301 light control device 401 liquid crystal panel 501 light guide 502 light introduction surface 503 LED
504 Lamp cover 505 Side surface of light guide

Claims

A light introduction surface for introducing light, a light extraction surface for extracting light introduced from the light introduction surface, and a back surface located on the opposite side of the light extraction surface, and the light introduced from the light introduction surface A light guide for guiding light in a predetermined direction,
As seen from a direction parallel to the light extraction direction, the concavo-convex structure A having an anisotropic shape in which the dimension in the predetermined direction is larger than the dimension in the direction orthogonal to the predetermined direction is formed on the light extraction surface and the back surface. A light guide having at least one of the surfaces.
The light guide according to claim 1, wherein the concavo-convex structure A is provided on both the light extraction surface and the back surface.
The light guide according to claim 1, wherein a main axis of the anisotropic shape of the concavo-convex structure A viewed from a direction parallel to a light extraction direction is parallel to the predetermined direction.
The light guide according to claim 1, wherein the concave portion of the concave-convex structure A is continuous.
The light guide according to claim 1, wherein the light guide has a flat portion in at least one of a concave portion and a convex portion of the concave-convex structure A.
The light guide according to claim 1, wherein the light guide has a light extraction structure for extracting light guided through the light guide from the light extraction surface at a portion having the uneven structure A of the light guide.
The light guide according to claim 6, wherein the light extraction structure is a concavo-convex structure B having a main axis of the anisotropic shape in a direction intersecting with the main axis of the anisotropic shape of the concavo-convex structure A.
The light guide according to claim 7, wherein the anisotropic main axis of the concavo-convex structure A is orthogonal to the anisotropic main axis of the concavo-convex structure B.
The light guide according to claim 6, wherein the light extraction structure is an unevenness formed on a surface of the uneven structure A.
The light guide according to claim 6, wherein the density or size of the light extraction structure increases as the distance from the light introduction surface increases.
The light guide according to claim 6, wherein the light extraction structure is a light diffusing agent present in the light guide.
The light guide according to claim 1, wherein the concavo-convex structure A has a ridge-like convex portion.
The light guide according to claim 7, wherein the concavo-convex structure B has a bowl-shaped convex portion.
The light guide according to claim 12 or 13, wherein the bowl-shaped convex part includes a prism having a triangular cross section or a lenticular.
An illumination device comprising: the light guide according to claim 1; and a light source that irradiates light to a light introduction surface of the light guide.
A plurality of the light sources;
The lighting device according to claim 15, wherein the plurality of light sources are dimmable individually or in groups.
The lighting device according to claim 15, wherein the light source is an LED.
LCD panel,
A liquid crystal display device comprising: the illumination device according to claim 15 provided on a back side of the liquid crystal panel.